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Synthesis and Photophysical Characterization of Pi-Extended Platinum Porphyrins for Application in High Efficiency Near-...

Permanent Link: http://ufdc.ufl.edu/UFE0041520/00001

Material Information

Title: Synthesis and Photophysical Characterization of Pi-Extended Platinum Porphyrins for Application in High Efficiency Near-Ir Light Emitting Diodes
Physical Description: 1 online resource (168 p.)
Language: english
Creator: Sommer, Jonathan
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: infrared, led, oled, platinum, pled, porphyrin, tetraanthroporphyrin, tetrabenzoporphyrin, tetranaphthoporphyrin
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: My research presents the synthesis and photophysical characterization of ?-extended platinum porphyrins. These novel near-IR phosphors have emission ranging from 770 to 1000 nm with the highest photoluminescence efficiencies ever reported. Organic light emitting diodes (OLEDs) that feature electroluminescence solely in the near-IR have been fabricated from these materials by two methods: thermal vapor deposition of small molecules (OLEDs) and solution processing with polymers to form thin films (PLEDs). The synthesis of the platinum complexes for ?-extended porphyrins has been retarded due to the difficulty and low yield by current methods. Developed herein is a novel metallation procedure to obtain for the first time platinum complexes for ?-extended porphyrins in high yield. This breakthrough has enabled the realization of these materials which would otherwise not be possible. The goal of the first series of ?-extended platinum porphyrins was to extend the conjugation of the porphyrin macrocycle so emission wavelengths could be obtained further in the near-IR. The addition of fused-benzene rings to the ?-carbons of the pyrrole residues effectively extends the conjugation of the porphyrin macrocycle. The platinum tetrabenzoporphyrins in the second series of target compounds were designed in efforts to increase the solution quantum yield. This was achieved by decreasing the non-radiative decay rate through increasing the planarity of the tetrabenzoporphyrin macrocycle by reducing the number of meso-aryl substituents. This resulted in the desired higher quantum yield. The third series of platinum tetrabenzoporphyrins examines the effects of a variety of substituents on the photophysical properties and device efficiency. The materials were designed in efforts to create a dye encapsulation effect to prevent self quenching mechanism caused by aggregation. The most important conclusions from this study are as follows: (i) the use of platinum acetate as the metallation reagent readily affords the desired platinum complexes; (ii) the lifetimes and quantum yields for series 1 ?-extended platinum porphyrins follows the energy gap law, were the lifetime and quantum yield decrease with longer emission wavelengths; (iii) increasing the macrocycle planarity decreases the non-radiative decay rate, thus increasing the quantum yield and lifetime; (iv) self quenching mechanisms from aggregation of the ?-extended platinum porphyrins in the host material of OLEDs and PLEDs remains a problem seriously limiting the device efficiency despite the high photoluminescence efficiency of the phosphors.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Jonathan Sommer.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: Schanze, Kirk S.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-02-28

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041520:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041520/00001

Material Information

Title: Synthesis and Photophysical Characterization of Pi-Extended Platinum Porphyrins for Application in High Efficiency Near-Ir Light Emitting Diodes
Physical Description: 1 online resource (168 p.)
Language: english
Creator: Sommer, Jonathan
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: infrared, led, oled, platinum, pled, porphyrin, tetraanthroporphyrin, tetrabenzoporphyrin, tetranaphthoporphyrin
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: My research presents the synthesis and photophysical characterization of ?-extended platinum porphyrins. These novel near-IR phosphors have emission ranging from 770 to 1000 nm with the highest photoluminescence efficiencies ever reported. Organic light emitting diodes (OLEDs) that feature electroluminescence solely in the near-IR have been fabricated from these materials by two methods: thermal vapor deposition of small molecules (OLEDs) and solution processing with polymers to form thin films (PLEDs). The synthesis of the platinum complexes for ?-extended porphyrins has been retarded due to the difficulty and low yield by current methods. Developed herein is a novel metallation procedure to obtain for the first time platinum complexes for ?-extended porphyrins in high yield. This breakthrough has enabled the realization of these materials which would otherwise not be possible. The goal of the first series of ?-extended platinum porphyrins was to extend the conjugation of the porphyrin macrocycle so emission wavelengths could be obtained further in the near-IR. The addition of fused-benzene rings to the ?-carbons of the pyrrole residues effectively extends the conjugation of the porphyrin macrocycle. The platinum tetrabenzoporphyrins in the second series of target compounds were designed in efforts to increase the solution quantum yield. This was achieved by decreasing the non-radiative decay rate through increasing the planarity of the tetrabenzoporphyrin macrocycle by reducing the number of meso-aryl substituents. This resulted in the desired higher quantum yield. The third series of platinum tetrabenzoporphyrins examines the effects of a variety of substituents on the photophysical properties and device efficiency. The materials were designed in efforts to create a dye encapsulation effect to prevent self quenching mechanism caused by aggregation. The most important conclusions from this study are as follows: (i) the use of platinum acetate as the metallation reagent readily affords the desired platinum complexes; (ii) the lifetimes and quantum yields for series 1 ?-extended platinum porphyrins follows the energy gap law, were the lifetime and quantum yield decrease with longer emission wavelengths; (iii) increasing the macrocycle planarity decreases the non-radiative decay rate, thus increasing the quantum yield and lifetime; (iv) self quenching mechanisms from aggregation of the ?-extended platinum porphyrins in the host material of OLEDs and PLEDs remains a problem seriously limiting the device efficiency despite the high photoluminescence efficiency of the phosphors.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Jonathan Sommer.
Thesis: Thesis (Ph.D.)--University of Florida, 2010.
Local: Adviser: Schanze, Kirk S.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-02-28

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041520:00001


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SYNTHESIS AND PHOTOPHYSICAL CHARACTERIZATION OF nr-EXTENDED
PLATINUM PORPHYRINS FOR APPLICATION IN HIGH EFFICIENCY NEAR-IR
LIGHT EMITTING DIODES
















By

JONATHAN ROBERT SOMMER


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2010

































2010 Jonathan Robert Sommer
































To my parents and to my friends for their unwavering love and support.









ACKNOWLEDGMENTS

I would like to express my gratitude to my advisor, Professor Kirk S. Schanze,

whose support and direction have helped me develop and enabled me to complete my

studies. His overall knowledge of science, not just chemistry, is extremely impressive.

The mentorship I received from him has guided me through my many challenges as a

graduate student and for that I will always remain appreciative and thankful for the

opportunity to have worked with him. I would especially like to thank, Dr. William Dolbier

and Dr. Kenneth Wagener for their time in the class room and also as members of my

committee. Their knowledge, advice, and support have been a valuable and cherished

resource during my graduate career.

This work would not have been possible with out the hard work of our many

collaborators with whom I have interacted: Dr. Ion Ghiviriga for his expertise in NMR

and help with characterization of the porphyrins prepared in Chapter 2; Dr. John

Reynolds and Dr. Jiangeng Xue for their collaboration and expertise in both chemistry

and light emitting diodes; Ken Graham for the fabrication and characterization of PLEDs

and our stimulating discussions on aggregation and device efficiency; Yixing Yang for

the fabrication and characterization of OLEDs; Dr. Richard Farley and Abby Shelton for

their help with the photophysical characterization of the platinum porphyrins synthesized

in Chapter 2. I would like to thank all of the present and past members of the Schanze

research group. I have made some great friends along the way and enjoyed watching

them grow into talented scientists.









TABLE OF CONTENTS

page

A C K N O W LE D G M E N T S .................................................................................. ......

LIST O F TA B LE S ...................................................................................... 7

LIS T O F F IG U R E S .................................................................. 8

LIST OF ABBREVIATIONS..................... .......... .............................. 12

A B S T R A C T ...................................................... 13

CHAPTER

1 INTRODUCTION TO PORPHYRINS.................... ................ 15

History and Discovery of Porphyrins- The Pigments of Life.................. ........ 15
Structure and Nomenclature of Porphyrins................ ................................. 16
History of Porphyrin Synthesis ........................ ........ ...................... 18
Synthesis of meso-Substituted Porphyrins ........... ..... .... ............ 19
Synthesis of rr-Extended Porphyrins.......................... .... .......... .... 21
Introduction to Photophysics ........... .................................... ........ ............... 28
A bsorption of Light .............................................................. .............. 28
Nature of the Excited State ................. ... ................ ............... 31
R elaxation of the Excited States................................................... ............... 32
P hotophysics of Porphyrins ...................... .. ............. ................... ............... 33
Absorption of Metalloporphyrins ........... ... ......... ........... .............. 33
Introduction to Porphyrin Emission............ ........... ................. .. ............ 36
Em mission from M etalloporphyrins .......................... ..... .................................. 36
Near-IR Light Emitting Diodes: State-of-the-Art......... ... ........ .. ............ 38
rr-Extended Platinum Porphyrins as Near-IR Phosphors............................... 41
Objective of Present Study .......... ........... ......... ........... ......... 44

2 SYNTHESIS OF n-EXTENDED PLATINUM PORPHYRINS.............................. 46

Introduction ............ .. .... .... .. ...... ..... ... ..................................... 46
Synthesis of Aromatic Aldehydes for rr-Extended Porphyrins....................... 51
Synthesis of Pyrroles for rr-Extended Porphyrins............... .... .......... 52
Synthesis of Symmetrical rr-Extended Porphyrins................................................ 55
Deprotection of Pyrrole Esters ............. .......... .......... ............ ... 55
Synthesis of Tetraaryltetrabenzoporphyrins............. ............... 56
Synthesis of Tetraaryltetranaphthoporphyrins................ .............. 57
Synthesis of Tetraryltetraanthroporphyrins ............... ....... ................ 58
Synthesis of 5,15-Diaryltetrabenzoporphyrins..................................... 59
Synthesis of rr-Extended Platinum Porphyrins ....... .... ................................ 60









C o nclusio ns ............................................ 6 3
Experimental ................... ... ......... ......... ......... 63

3 PHOTOPHYSICS AND DEVICE RESULTS.................... ............................... 95

Introduction .................. ......... ............... 95
Electrolum inescence M echanism s .............. .............. .............. .................. 96
Organic Light Emitting Diodes ................................................ 98
Polymer Light Emitting Diodes ........... ............................. 101
Results and Discussion.................................. ................. 102
Series 1- Photophysical Properties........ ............ ...................... 102
Series 1- PLED Device Results .................................. ...................... 110
Series 1- OLED Device Results .................................. ...................... 113
Series 2- Photophysical Properties........ ............ ...................... 114
Series 2- PLED Device Results ................ ......... ..... ....... .......... 121
Series 2- OLED Device Results ......................... ..... ............ ...... 122
Series 3- Photophysical Properties........ ............ ...................... 124
Series 3- PLED Device Results ................ ......... ..... ....... .......... 130
Series 3- OLED Device Results ......................... ..... ............ ...... 132
C conclusion ........... .. ........... ....... ..................................... ...... .... 133
Experim ental............................. ............... 134

4 CONCLUSIONS ................. ........... .......... ......... 137

APPENDIX

A FIGURES ................................................ ......... 140

B NMR SPECTRA......................................... ........... 148

LIST O F REFERENCES .. ................................. ........................................... 157

B IO G RA P H IC A L S K ET C H ...................... .. ............. .. ....................... ............... 168


















6









LIST OF TABLES


Table page

1-1 Recent literature reports of near-IR LED devices................. ...................... 39

3-1 Photophysical properties of Series 1 free-base rr-extended porphyrins........... 104

3-2 Deactivation rate constants for Si state of series 1 free-base rr-extended
p o rp hyrin s ............. ......... .. .. ......... .. .. .. ..... ............................... 10 5

3-3 Photophysical data for series 1 rr-extended platinum porphyrins.................... 107

3-4 Deactivation rate constants for T1 state of series 1 rr-extended platinum
p o rp hyrin s ............. ......... .. .. ......... .. .. .. ..... ............................... 10 7

3-5 Photophysical properties of Series 2 free-base TBPs ................................ 116

3-6 Deactivation rate constants for Si state of series 2 free-base TBPs ................ 117

3-7 Photophysical data for series 2 platinum TBPs ........................ ............. 117

3-8 Deactivation rate constants for T1 state of series 2 platinum TBPs .................. 121

3-9 Photophysical properties of Series 3 free-base TBPs ................................ 126

3-10 Deactivation rate constants for Si state of series 3 free-base TBPs ................ 126

3-11 Photophysical data for series 3 platinum TBPs ........................ ............. 128

3-12 Deactivation rate constants for T1 state of series 3 platinum TBPs.................. 130









LIST OF FIGURES


Figure page

1-1 Chlorophyll and heme are two naturally occurring porphyrins.......................... 15

1-2 Porphyrin nomenclature developed by Hans Fischer. ........... .. ..... ........ 17

1-3 The numerical IUPAC nomenclature for porphyrins ......................................... 17

1-4 Outline of the most common substitution patterns found around the porphyrin
m acrocycle ................................. ............. ......... ...... .............. 18

1-5 Outline of the synthetic conditions for the preparation of meso-aryl
substituted porphyrins ............................. ............... ......... ............... 20

1-6 General structures for phthalocyanine and meso-unsubstituted rr-extended
porphyrins..................... .............. ................. ............ 22

1-7 Initial synthetic strategy developed by Linstead and Tuey for the preparation
of T B P ............... ........... ....................... ............................ 23

1-8 Synthetic scheme reported by Kunkely and Volger in 1978 for the preparation
of ZnTBP .............. ......... ......... .... ...... ............ ......... 23

1-9 Outline of synthetic strategy to prepare H2TPTBP................... ........... ..... 24

1-10 The synthesis reported by Ono et al for the preparation of H2Ar4TBP................ 25

1-11 Outline of the oxidative aromatization strategy for the preparation H2Ar4TBPs.. 26

1-12 Synthetic strategy for H2Ar4TNP using the dihydroisoindole method.................. 27

1-13 Potential energy curves for electronic transitions ....... .............................. 30

1-14 Jablonski diagram showing the possible transitions for a singlet excited state
after absorption of a photon ............................................ ... ...... ........... ...... 32

1-15 Examples of metalloporphyrin absorption spectra.................... ............ 34

1-16 Jablonski diagram showing the decay schemes for singlet and triplet
relaxation after absorption of a photon. ............... ....... ......... ......... 35

1-17 Examples of metalloporphyrin emission ......... ...... ..... ... ..... ....... ... 37

1-18 Lanthanide based near-IR emission from lanthanide monoporphyrinate
complexes towards near-IR LED applications ....................... ....... .............. 40

1-19 Near-IR OLED device data for Pt-TPTBP doped in to Alq3.............................. 41









1-20 Current literature reports for free-base and metallo-TBPs............................. 42

1-21 Current literature reports for free-base and metallo-TNPs.............................. 43

1-22 Current literature reports for free-base and metallo-TAPs............................... 44

2-1 General structures for meso-unsubstituted rr-extended porphyrins .................. 46

2-2 Target free-base and platinum porphyrins towards new near-IR phosphors..... 49

2-3 Synthetic scheme for aromatic aldehydes towards meso-aryl substituted rr-
extended porphyrins ................ ................. ........... ................. 51

2-4 Synthetic scheme for benzopyrroles towards TBPs ................................ ..... 52

2-5 Synthetic scheme for naphthopyrroles towards TNPs .............. ............. 53

2-6 Synthetic scheme for anthropyrroles towards TAPs............... .................. 54

2-7 Synthetic scheme for the deprotection of pyrrole esters................ ............... 56

2-8 Synthetic scheme for H2Ar4TBPs ....... .... ....... .. ............. ............... 56

2-9 Synthetic scheme for H2Ar4TNPs ............. ....... ................... ............... 57

2-10 Synthetic scheme for H2Ar4TAP .... ............................................ 58

2-11 Synthetic scheme for H2Ar2TBPs ....... ......... .. ............................. 59

2-12 Platinum metallation reaction for Pt-TPTNP followed by UV-vis spectroscopy... 61

2-13 Synthetic scheme for rr-extended platinum porphyrins................. .......... 62

3-1 Single layer device structure for the first reported OLED and PLED................ 95

3-2 Device structure of a multilayer light emitting diode with a diagram of
electrolum inescence m echanism ............................................. .... ................. 98

3-3 Examples of small molecule hole transport materials ........ ............ ..... ........ 99

3-4 Examples of small molecule host materials........ ..... .. .................... ............... 99

3-5 Examples of small molecule electron transport materials.............................. 100

3-6 Examples of polymer host materials for polymer light emitting diodes ........... 101

3-7 Structures for series 1 rr-extended free-base and platinum porphyrins............ 103









3-8 Normalized absorption and photoluminescence of Series 1 free-base rr-
extended porphyrins ................ .................... ............... .............. 106

3-9 Normalized absorption and photoluminescence for series 1 rr-extended
platinum porphyrins. ........................... .. ... ............. ............... 109

3-10 PLED device results for series 1 rr-extended platinum porphyrins.................. 111

3-11 Hybrid PLED device for Pt-Ar4TAP.............................. ............. 112

3-12 OLED device results for series 1 rr-extended platinum porphyrins................. 114

3-13 Structures of free-base and platinum complexes for series 2 TBPs................. 115

3-14 Normalized absorption and photoluminescence of series 2 free-base TBPs.... 118

3-15 Normalized absorption and photoluminescence for series 2 platinum TBPs.... 119

3-16 PLED device results for series 2 platinum TBPs .......... ............. ........... 122

3-17 OLED device results for series 2 platinum TBPs........................................... 123

3-18 Structures of free-base and platinum complexes for series 3 TBPs ................ 125

3-19 Normalized absorption and photoluminescence for series 3 free-base TBPs. 127

3-20 Normalized absorption and photoluminescence for series 3 platinum TBPs.... 129

3-21 PLED device results for series 3 platinum TBPs. ............. ............... 131

3-22 OLED device results for series 3 platinum TBPs...................................... 133

A-1 Fluorescence lifetimes for Series 1 free-base rr-extended porphyrins ......... 140

A-2 T1-Tn absorption data for series 1 rr-extended platinum porphyrins ............. 141

A-3 Fluorescence lifetimes for Series 2 free-base rr-extended TBPs .................... 142

A-4 T1-Tn absorption data for series 2 rr-extended platinum TBPs ...................... 143

A-5 Fluorescence lifetimes for Series 3 free-base rr-extended TBPs ..................... 144

A-6 Normalized absorption and PL of H2TPTBP and H2ArF4TBP........................ 145

A-7 T1-Tn absorption data for series 3 rr-extended platinum TBPs. ...................... 146

A-8 Plot of the natural log of the non-radiative decay constant and the emission
maximum in eV for series 1 rr-extended plantium porphyrins......................... 147









CDCl3) spectrum of 6. ...... ...................... ..... ...............

C D CI3) spectrum of 17b. ........................... ... ..................

C D CI3) spectrum of 18b. ........................... ... ..................


148

148

149


B-1

B-2

B-3

B-4

B-5

B-6

B-7

B-8

B-9

B-10

B-11

B-12

B-13

B-14

B-15

B-16

B-17


NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR

NMR


(300

(300

(300

(300

(500

(500

(500

(500

(500

(500

(500

(500

(500

(500

(500

(500

(500


MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,

MHz,


pyridine-ds) spectrum of 39b .................................... 149


pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)

pyridine-ds)


spectrum of 39c. ............... .......... .........

spectrum of 40b ................... .......... .........

spectrum of 42. .................. .....................

spectrum of 45c .............. ..... .......... .........

spectrum of 45d .................. ...................

spectrum of Pt-39b. ....................................

spectrum of Pt-39c. ............... ...............

spectrum of Pt-40a. ................... .. .............

spectrum of Pt-40b. ................................

spectrum of Pt-42. ........... ....................

spectrum of Pt-45b. ....................................

spectrum of Pt-45c. ............... ...............

spectrum of Pt-45d. ....................................


150

150

151

151

152

152

153

153

154

154

155

155

156










LIST OF ABBREVIATIONS

DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene

DCM Dichloromethane

DDQ 2,3-dichloro-5,6-dicyanobenzoquinone

EtOH Ethanol

m-CPBA 3-Chloroperoxybenzoic acid

MeOH Methanol

ITO Indium tin oxide

tBuOK Potassium tert-butoxide

OEP Octaethylporphyrin

PBD 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole

Pc Phthalocyanine

PEDOT Poly(3,4-ethylenedioxythiophene)

PhCN Benzonitrile

PSS Poly(styrenesulfonate)

PVK Poly(9-vinylcarbazole)

TAP Tetraanthroporphyrin

TBP Tetrabenzoporphyrin

TFA Trifluoroacetic acid

THF Tetrahydrofuran

TNP Tetranaphthoporphyrin

TPP Tetraphenylporphyrin

TsCI m-Toluenesulfonyl Chloride

TsOH p-Toluenesulfonic acid

ZnTBP Zinc(ll) Tetrabenzoporphyrin









Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

SYNTHESIS AND PHOTOPHYSICAL CHARACTERIZATION OF nr-EXTENDED
PLATINUM PORPHYRINS FOR APPLICATION IN HIGH EFFICIENCY NEAR-IR
LIGHT EMITTING DIODES

By

Jonathan Robert Sommer

August of 2010

Chair: Kirk S. Schanze
Major: Chemistry

My research presents the synthesis and photophysical characterization of rr-

extended platinum porphyrins. These novel near-IR phosphors have emission ranging

from 770 to 1000 nm with the highest photoluminescence efficiencies ever reported.

Organic light emitting diodes (OLEDs) that feature electroluminescence solely in the

near-IR have been fabricated from these materials by two methods: thermal vapor

deposition of small molecules (OLEDs) and solution processing with polymers to form

thin films (PLEDs).

The synthesis of the platinum complexes for rr-extended porphyrins has been

retarded due to the difficulty and low yield by current methods. Developed herein is a

novel metallation procedure to obtain for the first time platinum complexes for n-

extended porphyrins in high yield. This breakthrough has enabled the realization of

these materials which would otherwise not be possible.

The goal of the first series of rr-extended platinum porphyrins was to extend the

conjugation of the porphyrin macrocycle so emission wavelengths could be obtained

further in the near-IR. The addition of fused-benzene rings to the 3-carbons of the









pyrrole residues effectively extends the conjugation of the porphyrin macrocycle. The

platinum tetrabenzoporphyrins in the second series of target compounds were designed

in efforts to increase the solution quantum yield. This was achieved by decreasing the

non-radiative decay rate through increasing the planarity of the tetrabenzoporphyrin

macrocycle by reducing the number of meso-aryl substituents. This resulted in the

desired higher quantum yield. The third series of platinum tetrabenzoporphyrins

examines the effects of a variety of substituents on the photophysical properties and

device efficiency. The materials were designed in efforts to create a dye encapsulation

effect to prevent self quenching mechanism caused by aggregation.

The most important conclusions from this study are as follows: (i) the use of

platinum acetate as the metallation reagent readily affords the desired platinum

complexes; (ii) the lifetimes and quantum yields for series 1 rr-extended platinum

porphyrins follows the energy gap law, were the lifetime and quantum yield decrease

with longer emission wavelengths; (iii) increasing the macrocycle planarity decreases

the non-radiative decay rate, thus increasing the quantum yield and lifetime; (iv) self

quenching mechanisms from aggregation of the rr-extended platinum porphyrins in the

host material of OLEDs and PLEDs remains a problem seriously limiting the device

efficiency despite the high photoluminescence efficiency of the phosphors.









CHAPTER 1
INTRODUCTION TO PORPHYRINS

History and Discovery of Porphyrins- The Pigments of Life

The vast majority of complex animal and plant life that exists on our planet today

results from a class of compounds called porphyrins. Photosynthesis and respiration are

at the heart of what makes life possible. During the Archean eon life on earth was

dominated by bacteria and archaea with the atmosphere void of free oxygen. The

evolution of oxygenic photosynthesis from cyanobacteria changed the earth and its

atmosphere forever.1 The process involves the oxidation of water forming molecular

oxygen releasing it into the atmosphere. Eventually the earth's atmosphere changed

from anaerobic to aerobic leading to a dramatic increase in biodiversity. Life has since

evolved using oxygen leading to eukaryotic organisms and plants containing

chloroplasts for photosynthesis and eventually hemoglobin in the red blood cells for the

respiration of vertebrates (Figure 1-1). It is from the desire of scientist to understand

these vital life processes that porphyrins were discovered.










A B

Figure 1-1. Chlorophyll and heme are two naturally occurring porphyrins. A)
Microscope image of chloroplasts visible in the cells of Plagiomnium affine B)
SEM image of human red blood cells which contain the iron porphyrin heme.









The main historical events that led to the discovery of porphyrins has been the

subject of many reviews and summarized by Sheldon.2 The existence of iron in human

blood was first reported in 1747 when Menghini burned human blood to ash separating

particles of iron with a magnet. Later the experiments by an English chemist named

Joseph Priestly in 1774 proved that the oxygen consumed by fire and breathing animals

could be restored to the air by plants. This ignited interest in understanding the role of

oxygen in respiration. In 1841, treating powdered blood with sulfuric acid Scherer was

able to isolate the iron free pigment in blood. A German chemist named Felix Hoppe-

Seyler in 1864 was able to isolate the iron-containing oxygen-transport metalloprotein

found in red blood cells naming it hemoglobin. Later in 1871 Hoppe-Seyler isolated

porphyrins from blood and proved they were pyrrole derivatives and is credited with

noting the structural similarities between chlorophyll and heme in 1879. It was not until

1912 that the correct structure for porphyrins was proposed by KOster although at the

time not accepted. Milroy published the first general synthesis of porphyrins in 1918.3

Later the work of Hans Fischer in 1926 who was awarded the Nobel Prize in 1930 for

his work in 1929 the de novo synthesis of chlorohemin which proved the structure

proposed by KOster almost twenty years earlier.4

Structure and Nomenclature of Porphyrins

Fischer also developed the first system of nomenclature outlined in his book Die

Chemie des Pyrrols published in 1934 for the naming of porphyrin compounds.5 The

general unsubstituted structure of a porphyrin is often referred to as porphine and is

outlined in Figure 1-2. Substitution can occur at two positions along the periphery of the

macrocycle in the 3-carbons of the pyrrole fragments or at the four meso-positions

which are the methine bridges between the a-carbons of the pyrrole fragments. The









nomenclature developed by Fischer is frequently used today, although another system

was developed in effort to name more complicated structures where the Fischer

nomenclature failed.

f -pcsition 2 3

NN HH









The nomenclature developed by the International Union of Pure and Applied
7 6
A B C






Figure given 1-2. Porphyrin nomenclature developed by Hans Fischer. A) Nomenclature -carbons were not







numbered because they could not be substituted and the meso-positions were denoted
by Greek letters. Looking at the basic porphyrin systempositions B) Numbering for -positions C) Greek letter notation for
become 2,3,7,8,12,so-positio18, and 17 instead of 1-8. The mes-positions are numbered

5,10,15,20 in pomenclace of the Greek letters Fischer prevional Unionsly assigned
Chemistry (IUPAC) was adopted in the early 1970's (Figure 1-3).6 This nomenclature

differs from Fischer's in that all the carbon and nitrogens in the porphyrin macrocycle













3 7 5 345 7
2 2 3
2"0 t0 4L "24 23Y O
19,-- N HN .11

17 13 15 I 15 1
A B C

Figure 1-3. The numerical IUPAC nomenclature for porphyrins.6 A) Numbering for P-
positions B) Numbering for meso-positions C) Complete IUPAC numbering.

Naming porphyrins is relatively simple when all the substituents around the

macrocycle are the same. Two examples would be if all the meso-positions were









substituted with phenyl substituents to give tetraphenylporphyrin (H2TPP) and

alternatively if all the 3-positions were substituted with ethyl groups to give

octaethylporphyrin (H2OEP). However the naming of porphyrins becomes increasingly

difficult with lower symmetries arising from different substituents at either the 3- or

meso-positions.

History of Porphyrin Synthesis

The need for developing practical and efficient synthetic methods for the

preparation of porphyrins was born when Fischer confirmed the porphyrin structure in

1929. The significant biological roles and photophysical properties of porphyrins has

driven the attention of researchers over the past century. Although at first thorough

exploration of these compounds has been severely limited by their synthetic availability.

This provided the inspiration for synthetic chemists to develop efficient synthetic

methods for their preparation. It is worthwhile to examine the history and synthetic

advancements made to completely appreciate the progress that has been made in this

field.

R R R
H R( 'NH NN N4 N
SHNN HNIN
R R R
A B C

Figure 1-4. Outline of the most common substitution patterns found around the
porphyrin macrocycle. A) 3- and meso-unsubstituted porphine B) 3-
substituted OAPs C) meso-aryl substituted porphyrin.

The synthesis of porphyrins can be divided into three main categories consisting of

the 3- and meso-unsubstituted porphine; P-substituted porphyrins referred to as

ocatalkylporphyrins (OAPs) and finally meso-aryl substituted porphyrins. These









structures are illustrated in Figure 1-4. Since the focus of this work is on meso-aryl

substituted porphyrins the initial synthetic strategies developed for the synthesis of

porphine and OAPs will not be examined and have already been well reviewed.7 It is

worth noting that both porphine and OAPs closely resemble the porphyrins found in

biological systems. This chemistry was developed in order to synthesize naturally

occurring porphyrins such as heme and chlorophyll.4' 8

Synthesis of meso-Substituted Porphyrins

Although meso-substituted porphyrins are not naturally occurring compounds they

have provided chemists and other scientist with a multitude of applications and

fundamental studies. This stems from the simplicity in their preparation where one pot

synthesis are normal. On the other hand porphyrins with biological relevance are

unsymmetrical and therefore cannot be prepared via simple routes.7 This is the

attraction to meso-substituted porphyrins where their symmetry enables their simple

preparation from starting materials such as pyrrole and benzaldehyde.9

The initial work on meso-substituted porphyrins began in 1935 when Rothemund

first developed a method for the synthesis of meso-tetramethylporphyrin from heating

acetaldehyde and pyrrole in methanol at 950C.10 Rothemund later expanded the scope

of this method to include a variety of aromatic aldehydes in 1936, including

benzaldehyde to yield H2TPP.11 In 1941 Rothemund described in detail the preparation

of H2TPP in a reported 7-9% yield from heating 10 mL of pyrrole and 20 mL of

benzaldehyde in 20 mL of pyridine at 220C for 48 hours.12 The Rothemund method can

be summarized as using high reactant concentrations at high temperatures in absence

of an added oxidant.









Improvement in the synthesis of meso-substituted porphyrins came in the mid-

1960s from Alder and Longo. The new method utilized lower reactant concentrations

compared to the Rothemund method. The reactants were heated in acidic solvents with

the reaction vessels open to air. This enabled the preparation of a variety of meso-

substituted porphyrins in a 30-40% yield.13' 14 Optimized conditions were obtained by

increasing the reactant concentrations and using propionic acid (bp 141 C) rather than

other lower boiling acidic solvents like acetic acid. Heating the reaction to reflux open to

air and then cooling yielded crystals of the desired porphyrin.14 This advancement

prompted a mechanistic study by Dolphin who examined the condensation of 3,4-

dimethylpyrrole with benzaldehyde in refluxing acetic acid under anaerobic conditions.

This led to the formation of the porphyrin precursor octamethyltetraphenylporphyrinogen

which could then be oxidized to octamethyltetraphenylporphyrin.15 This result is

important as it provides very strong evidence that the precursor porphyrinogen is

formed followed by oxidation to the porphyrin.

RH H
R.? *E ThA orFEt R NHHNR 3 equiv.DDQ Q Nj
TFA or BR NH HN R NH
H DCM, 250C H HN H DCM, 25PC N HN
H^ R

Figure 1-5. Outline of the synthetic conditions for the preparation of meso-aryl
substituted porphyrins by Lindsey in 1987.1 17

It was not until the late-1980s that Lindsey et al reported a new synthetic method

that set the standard for meso-aryl substituted porphyrin.16 17 The methodology allows

for a wider variety of substituted aldehydes to be incorporated into the subsequent

porphyrins. The reaction can be scaled up to provide gram scale quantities and is

reproducible with typical yields in the range of 30-40% for substituted benzaldehydes.









Lindsey et al developed this method as a single flask two step reaction based on

equilibrium cyclizations and biomimetic studies of porphyrin biosynthesis and is outlined

in Figure 1-5. The first step is the acid catalyzed condensation to form the intermediate

porphyrinogen, followed by the second step the addition of an external oxidant such as

DDQ or chlorinal to form the porphyrin.

The method was developed on the premise that tetraphenylporphyrinogen would

be the thermodynamically favored product from the condensation of pyrrole and

benzaldehyde under favorable conditions. Also important were to keep the reaction

conditions mild utilizing the fact that benzaldehyde and pyrrole are reactive molecules

and high temperatures are unnecessary. This enabled new functionalities on substituted

benzaldehydes to be compatible with the given reaction conditions. The previous

methods used harsh reaction conditions which limited the scope of possible substituents

available at the meso-position.

Synthesis of rr-Extended Porphyrins

Porphyrin systems with 3-fused benzene rings represent an interesting class of

compounds. The structures for tetrabenzoporphyrin (H2TBP), tetranaphthoporphyrin

(H2TNP), and the related phthalocyanine (Pc) are outlined in Figure 1-6. The TBP and

TNP systems, now commonly referred to as rr-extended porphyrins caught the attention

of researchers early on for their photophysical properties relative to those of regular

porphyrins. The effect on the optical properties of the porphyrin macrocycle from the 3-

fused benzene rings was studied by the Gouterman in the 1960s.18-20 These studies

provided the data that set forth the motivation to develop efficient synthetic methods to

access these compounds for further characterization and use in a multitude of

applications.
















A B C
NH N NH N) NH r N
N N





Figure 1-6. General structures for phthalocyanine and meso-unsubstituted -r-extended
porphyrins: A) Phthalocyanine (Pc), B) Tetrabenzoporphyrin (H2TBP), C)
Tetranaphthoporphyrin (H2TNP).

The initial methods to synthesize TBPs were derived from that of Pc chemistry

developed by Linstead in 1934.21 It was later in 1940 that Tuey and Linstead

successfully produced H2TBP and its aza-substituted derivatives.22 23 The method

involves heating 3-carboxymethylphthalimide above 3000C in the presence of zinc or

zinc acetate to give the zinc (II) tetrabenzoporphyrin (ZnTBP) in a very low yield (Figure

1-7). Analytically pure samples were obtained by sublimation or crystallization. The

authors were able to isolate the free-base (H2TBP) after treating the zinc complex with

acid enabling the synthesis of the respective copper and iron complexes. This method

was later refined by Gouterman in 1976 obtaining ZnTBP in a 14.5 % yield,18 although

extensive purification was required. The crude sample was sublimed and then further

purified by multiple chromatography columns. The final product was obtained by

precipitation into methanol.

Finally a method developed by Kunkely and Volger in 1978 provided ZnTBP and

was regarded as the simplest way to synthesize the TBP macrocycle.24 It requires

heating 2-acetylbenzoic acid to high temperature with ammonia and zinc acetate

(Figure 1-8). This affords ZnTBP in a moderate 17% yield and until recently was









regarded as the most direct and convenient method for synthesizing the meso-

unsubstituted TBP.

A ev \
~ Mg(O} NMgN


O N N
4 H 38 NH3 N N25C






D N
4 NH Zn(OAc) r .
o


Figure 1-7. Initial synthetic strategy developed by Linstead and Tuey for the preparation
of TBP. A) Linstead synthesis of Pc in 193421 B) Linstead synthesis of TBP in
1940.22, 23




ZnI(OAc),. NaOH 1N N
4
N I'H. 400*C, 1,5 hru N'K




Figure 1-8. Synthetic scheme reported by Kunkely and Volger in 1978 for the
preparation of ZnTBP.

Researchers eventually developed synthetic methods for the preparation of

tetraaryltetrabenzoporphyrins (H2Ar4TBP). The synthesis was motivated by the idea of

combining the properties of H2TPP with the TBP structure. The early reports for the

synthesis of H2TPTBP were developed from strategies analogous to the reported

methods for preparing H2TBP (Figure 1-9). The initial method appeared in 1981

described by Kopranenkov et al used 3-benzylidenephthalimide or alternatively the

potassium salt of phthalimide and phenylacetic acid with zinc acetate to give ZnTPTBP

(Figure 1-9B).25 Two years later, Remy published a method using the most logical









retro-synthetic precursor of the TBP macrocycle.26 The high temperature condensation

of isoindole with benzaldehyde and zinc acetate also afforded ZnTPTBP (Figure 1-9C).

Although earlier in 1972, Bonnet had published a communication describing the

instability of isoindole and the rapid decomposition at room temperature.27 Thus the

reproducibility of these methods was scrutinized by other groups that reported mixtures

of products identified as TBPs with varying numbers of meso-aryl substituents.28-30 Later

in 1991, Ohno et al showed that using zinc benzoate in place of zinc acetate with 3-

benzylidenephthalimide heating to high temperatures yielded ZnTPTBP without side

products (Figure 1-9A).29

B

A C CN


High Temp 'N,

0-_iM Q CNH


Figure 1-9. Outline of synthetic strategy to prepare H2TPTBP. A) Ohno et al synthesis of
H2TPTBP without side products B) Kopranenkov et al synthesis of
H2TPTBP25 C) Synthesis of H2TPTBP from isoindole reported by Remy.26

Another approach to synthesizing rr-extended porphyrins was developed by Ono

et al.31' 32 The new method uses a bicyclic pyrrole precursor serving as a protected form

of the simplest retro-synthetic precursor isoindole. This enabled the cyclization of the

porphyrin macrocycle to occur under mild Lindsey conditions avoiding the high

temperature reactions of Pc based related strategies. The key starting material 4,7-

dihydro-4,7-ethano-2H-isoindole was prepared from a Barton-Zard pyrrole synthesis

outlined in Figure 1-10. This synthetic strategy yielded the bicyclic-TPTBP precursor









under Lindsey conditions in a 35% yield. The solid state retro-Diels-Alder (RDA)

reaction requires temperatures of 2000C and produces ZnTPTBP quantitatively with no

required purification. This method is powerful in avoiding the major pitfall of the previous

methods which required much higher temperatures and extensive purification with lower

yields in comparison.


S+ G CHCb A! CN!CH Fh4OJS Rsfl ux N DBU Le.CN COE

KOH, 170T
HO(CHz)zOH


N :4 =< z.v cl-Ic. -H-NH '4 ThCH CHCIjh-+(
s F, 10 mTl N~pchinrani a




Figure 1-10. The synthesis reported by Ono et al for the preparation of H2Ar4TBP using
Lindsey conditions and a bicyclic-pyrrole as a protected form of isoindole.31'32

Using a similar synthetic strategy to the one developed by Ono, another method

for the preparation of rr-extended porphyrins was developed by using a different

approach to a masked-isoindole derivative. This method was developed by Cheprakov

et al in 2001 and is based on using tetrahydroisoindoles as the key starting material.33

The synthetic scheme is depicted in Figure 1-11. The tetrahydroisoindoles are prepared

from a modified Barton-Zard synthesis to produce the cyclic pyrrole from vinyl sulfones

instead of nitro alkenes.34 35 After cleavage of the ester, the deprotected pyrrole is

subjected to Lindsey conditions and gives the tetracyclohexenoporphyrin precursor in

good yields. Attempts at aromatizing the free-base porphyrin directly by refluxing with

DDQ failed to give H2TPTBP. Alternatively the precursor porphyrin was metallated and









then subjected to oxidizing conditions with excess DDQ in THF to give the metallated

TPTBPs in near quantitative yield. This methodology has advantages over Ono's

method in that it broadens the scope of meso-aryl substituents compatible with the

reaction conditions. However despite the improvement over the retro-Diels-Alder

approach which requires temperatures at 2000C, this method still suffered from over

oxidation of the TBPs due to the long reaction times required in the oxidative

dehydrogenation with DDQ. This drawback led to further improvements to the present

oxidative aromatization method for the preparation of rr-extended porphyrins.

MeO2C ,Me
PhOS
SDMM, py ECOMB PhSCI. mCPBA G CNCH2CO2'Bu
S 140 "C DBU, DCM '-BuoK TMF "COEt
CO2Me I
TFA
.- {M B t MDCM
SC Co2M e MeO,C COme

ZniZnOAc, CI-IC Nie l N 0 yS e
N DDQ,THF HI DDO

MeO-C COMe MeQC -COMe
MeDyC COMe MWoC CO,Me

Figure 1-11. Outline of the oxidative aromatization strategy for the preparation
H2Ar4TBPs reported by Cheprakov et al.33

A recent paper by Cheprakov and Vingradov in 2005 describes the synthesis of

H2Ar4TNPs using the oxidative aromatization methodology previously described.36 The

advancement in synthetic strategy is in choosing the pyrrole precursor to resemble

isoindole as much as possible. The two key starting materials examined are cis-octalin

and 1,4-dihydronaphthalene (Figure 1-12). The pyrroles for each strategy were

synthesized in a parallel manner to the scheme used for the H2Ar4TBP synthesis. The

pyrrole from the cis-octalin route was condensed with an aromatic aldehyde under









Lindsey conditions and provided the tetra-aryl cycloalkene-fused porphyrin. This

precursor to the H2Ar4TNP system was metallated and then subjected to oxidative

conditions with DDQ under reflux. The highest yield obtained from this route was 40-

45% from the palladium complex. The copper complex provided the H2Ar4TNP in a 20%

yield and efforts to oxidize the zinc complex resulted in demetallation and the formation

of a porphyrin dication. In comparison to the analogous H2Ar4TBP system the cis-

octaline scheme to prepare H2Ar4TNPs is less efficient.

A) OCIsfin Ro!ute B.; ,OJ.f/ r.r foe Roule

ci SOPh Cl SOPh
SPhSCI DCM PhSC, DCM
m-CPBA m-CPBA
CNCH2CO2Et CNCH2CO2Et
TI-IF, 'BuOK TI-IF, rBuOK


1) Lindsey N N 1) Lindsey 0
SConrditions,_ I M CDdritioRnsB 4
2} Metallation N NrAIX 2) DDQDCM 0.Q
N 3} DDQ, PhMe rt r refluxj
Reflux M= H2
M= Pd, Cu

Figure 1-12. Synthetic strategy for H2Ar4TNP using the dihydroisoindole method
developed by Vinogradov et a/.36 A) Octalin strategy towards H2Ar4TNP B)
Dihydroisoindole strategy towards H2Ar4TNP.

Alternatively the route from the key starting material 1,4-dihydronaphthalene

smoothly gave 4,9-dihydro-2H-benzo[f]isoindole which under Lindsey conditions in the

presence of an aromatic aldehyde gave the desired H2Ar4TNPs after the addition of

DDQ. Despite the authors' efforts they were not able to isolate the intermediate

porphyrin, which was possible in both the previous octalin and TBP schemes. The

overall yield from the Lindsey condensation ranged between 35-50% providing excellent

access to the H2Ar4TNP system without the requirement of a metallation/demetallation









step. This new strategy was termed the dihydroisoindole method and later applied to the

H2Ar4TBP and the tetraanthroporphyrin (H2Ar4TAP) systems.37' 38 This strategy

represents the most powerful method available for the preparation of rr-extended

porphyrins. In both the H2Ar4TNP and H2Ar4TAP systems the oxidative aromatization

occurs almost instantly with the intermediate porphyrins to date not isolated. Only in the

H2Ar4TBP system must the temperature be elevated to 100C for a short period of time

to complete the oxidative aromatization.

Introduction to Photophysics

The interaction of light with matter is something that has caught the interest of

scientist since the early 15th century. At the end of the 19th century it was generally

accepted that light was a wave and electrons were particles. In the beginning of the 20th

century Planck's blackbody experiment concluded that blackbody radiation was limited

to finite values of energy. This meant that the energy was quantized and changed the

views of light as a wave. Einstein later discovered the photoelectric effect, further

cementing the idea of light having wave and particle like properties. Although for most

purposes the Maxwell wave equations from 1860 generally explain most of the light-

related phenomena. These findings laid the foundation for de Broglie in 1924 to

theorize that all particles act as waves. This led to the Schr6dinger equation in 1924

which enabled the description of the wave nature of electrons mathematically. The

impact of these discoveries has dramatically changed our understanding of atomic and

molecular structure.

Absorption of Light

When light interacts with matter it has three possible pathways in that it is either

reflected, transmitted or absorbed by the material. The latter pathway often referred to









as absorption can provide important information regarding the electronic molecular

structure of a molecule. The absorption of a photon promotes a ground state electron to

a higher energy level called an excited state. The difference in energy between these

two energy levels is equal to the energy of the absorbed photon. This allows for

elucidation of the molecular energy levels of a molecule. The energy of a photon is

proportional to the frequency of its electromagnetic wave and is described by the

following equation:

hec
E = hv =-
A (1-1)

where E is the energy of the photon, h is Planck's constant, v is the frequency, c is the

speed of light, and A is the wavelength of the photon. Since the electronic energy levels

of a molecule are finite the ground state electrons absorb photons of different

wavelengths (different energy) with different efficiencies. The efficiency of which a

certain wavelength of light is absorbed is described by the molar absorptivity which is

described by Equation 1-2.

A = bC (1-2)

Where A is the absorbance, E is the molar absorptivity (units of M-1 cm-1), and b is

the path length of absorption and C representing the molar concentration of the

absorbing compound. The molar absorptivity represents the probability of the transition

to occur and is directly related to the transition dipole moment between the initial and

final states.

Another important principle to understand is the Franck Condon principle. This

explains why the absorption bands in molecules appear as broad bands instead of the

predicted sharp lines based on the discrete electronic energy levels. This is not the case










because of the difference in time scale between the excited electron (10-15 s) and the re-

adjustment time of the nuclei (10-13 s) and is referred to as the Franck-Condon principle

(Figure 1-13).


potential


nuclear configuration


potential
energy


--Im


nuclear configuration


Figure 1-13. Potential energy curves for electronic transitions. A) Electronic transitions
between states of similar equilibrium nuclear geometry. B) Electronic
transitions between states of different equilibrium nuclear geometry. This
figure was adopted from Gilbert and Baggot.39

This is illustrated by potential energy curves of the ground and excited states as a

function of equilibrium geometry. The electronic transitions are termed "vertical" to

illustrate absorption occurring without any changes in the equilibrium geometry. This

allows for electrons to be promoted to higher excited states regardless of any









differences in equilibrium geometry between the ground and excited state. After

absorption the molecule will relax to the lowest vibrational excited state (v' = 0). This

relaxation results in a loss of energy and is the reason why the energy between the

ground state (v" = 0) and some vibrational excited state (v' > 0) will always be higher in

energy than the 0-0 transition.

Nature of the Excited State

Following absorption of a photon from the ground state (So) the electronic excited

state (Si) is created and represented by a vertical arrow (solid) in the Jablonski diagram

(Figure 1-14). The molecule will first relax from higher vibrational levels (v > 0) to the

lowest energy vibrational level (v = 0). This process occurs through two types of

relaxation thermal (loss of heat) and collisional (with other molecules) and is illustrated

by the dashed arrow. When the ground state is neutral the electrons in the highest

occupied molecular orbital (HOMO) are paired and have opposite spins according to

Hund's rule. When the electron is promoted to the excited state the spin is forbidden to

change due to spin restrictions imposed by quantum mechanics and is therefore termed

a singlet excited state (Si). It is possible in some cases for the spin of the excited

electron to flip; this process is referred to as intersystem crossing (ISC). This creates a

situation where both electrons have the same spin. Excited states of this nature are

referred to as triplet excited states (Ti). Similar to the singlet excited state the vibrational

energy level is greater than zero for the initially formed triplet state and fast relaxation

occurs to the lowest energy vibrational level (v = 0). Typically organic molecules have

very low rates of ISC therefore the resulting triplet yields are very low. The rate of ISC

can be enhanced by the addition of heavy atoms in a process known as the heavy atom

effect. The process of ISC involves the conservation of total orbital angular momentum










and in heavy atoms the spin angular momentum and orbital angular momentum are not

individually conserved. This facilitates spin-orbit coupling and increases the rate of the

electron spin flip to form the triplet excited state. This allows inorganic and

organometallic compounds such as platinum porphyrins to have large triplet quantum

yields.

A: absorption
F: fluorescence
P: phosphorescence
So: ground state
Si: singlet excited state
-3 Ti: triplet excited state
S IC v = 2 IC: internal conversion
S- V1 ISC: intersystem crossing
I v oISC
'"' -~~~ ~~ --, -------- V3
|- I v=3
I2
T1 IC-- v=


A F 1C
P IIC



So -___


Figure 1-14. Jablonski diagram showing the possible transitions for a singlet excited
state after absorption of a photon.

Relaxation of the Excited States

The triplet and singlet excited states are metastable, meaning they are stable and

have long lifetimes but are transient in nature and eventually will relax to the ground

state. The two pathways by which the self-relaxation mechanisms can occur are

radiative and non-radiative decay. The latter represents the return of the excited

electron to the ground state without the emission of a photon. Instead the energy is

released as heat to the system when non-radiative decay occurs. This process and

vibrational relaxation pathways are referred to as internal conversion (IC) on the

Jablonski diagram (vertical dashed lines). The rate of non-radiative decay is governed









by the energy gap law. This law states that as the gap (energy difference) between the

excited and ground states becomes lower in energy the rate of non-radiative decay will

increase exponentially. Simply put one could expect that a fluorophore emitting light at

450 nm would have a smaller non-radiative decay rate than a fluorophore emitting at

700 nm due to the smaller gap in energy between the excited and ground state.

Photophysics of Porphyrins

The aesthetically pleasing purple color of porphyrins is the direct result of their

unique absorption. Understanding what gives rise to their fascinating optical absorption

and emission spectra has been an intriguing topic for researchers. The 18 rr-electrons

in the 16-membered porphyrin ring are responsible for the general optical spectra

observed. However influences from external substituents and changes in conjugation

pathway as well as change in the central substituents all lead to moderate to strong

changes in optical absorption and emission spectra. The characterization of porphyrin

absorption and emission spectra based on substitution patterns and different central

substituents has been well studied and review elsewhere. The focus of this work is on

one class of metalloporphyrins, specifically platinum (II) porphyrins.

Absorption of Metalloporphyrins

Metalloporphyrins typically differ very little by optical absorption spectra, but more

so in emission from metal to metal. The addition of a metal to the center of the porphyrin

changes the overall symmetry to D4h from the lower D2h symmetry of the free-base

porphyrin. The absorption spectra for ZnTPP and Pt-TPP in toluene are shown in Figure

1-15. Two visible bands are typically seen between 500-600 nm called the Q-band with

molar absorptivity constants in the range of 1.2-2 x 104 M-1 cm1. The Q-bands is a

quasi-allowed transition. The lower energy band (a) is separated by approximately 1250










cm1 from the higher energy band (3). The a band represents the electronic origin of

Q(0,0) of the lowest energy singlet excited state. One mode of vibrational excitation in

the singlet excited state is denoted by Q(1,0) and is represented by the 3 band.

The Soret band, often referred to as the B-band, is an intense band to the blue of

the Q-band between 380-420 nm and is strongly allowed. Typical molar absorptivity

constants for this band are in the range of 2-4 x 105 M-1 cm1. The electronic origin of the

Soret band is B(0,0) of the second singlet excited state additionally with better resolved

spectra another band appears to the blue (~1250 cm-1) representing one mode of

vibrational excitation B(1,0).

1.2

1.0 -
o
L 0.8
0

0.6
N 450 500 550 600
0.4

0.2

0.0
300 400 500 600
Wavelength (nm)

Figure 1-15. Examples of metalloporphyrin absorption spectra for ZnTPP (blue) and Pt-
TPP (green) in toluene with the Q-band region magnified in the inset.

The metalloporphyrins are classified into two classes called "regular' and

"irregular'. This is based on whether or not the coordinated metal has a closed or open

shell of valence electrons. The metalloporphyrins classified as "regular' give normal

optical absorption and emission spectra. The normal absorption spectra are primarily









based on the porphyrin's rr-electrons with the atomic orbitals of the coordinated metal

having little interaction with the rr-molecular orbitals of the porphyrin ring.

The irregular metalloporphyrins show spectra that are classified into three main

types called normal, hypso, and hyper. The orbitals of the coordinated metal have a

much stronger effect on optical spectra due to stronger mixing with the porphyrins n-

electrons. The metals from the d- or f-block where the metal electrons are lower in

energy and do not sufficiently interact with the porphyrins rr-electrons give normal-type

absorption spectra. An example of this would be zinc tetraphenylporphyrin (ZnTPP).

The hypso-type spectra also resemble the normal spectra but the Soret and Q

bands are blue shifted relative to the free-base porphyrins absorption spectra. This

results from metals in the d-block with unfilled d-orbitals (d6-d9). The d-electrons from

the metal may be donated into the -n*-orbitals of the porphyrin resulting in metal-to-ring

charge transfer. This has the effect of increasing the energy of the porphyrins un-nr*

transition and thus blue shifting the absorption spectra. The blue shift increases with

atomic number of the transition metal for example in series of Ni(ll), Pd(ll), and Pt(ll).

Si


S1 -,> k
k2 T"' ,

K kf ki

k3,


So I

Figure 1-16. Jablonski diagram showing the decay schemes for singlet and triplet
relaxation after absorption of a photon. The radiation processes depicted as
solid lines and radiationless processes as dashed lines.









Introduction to Porphyrin Emission

One of the first reports of emission observed from a porphyrin was from the

reduced porphyrin chlorophyll in 1834. The energy level diagram in Figure 1-16

illustrates the possible pathways of the singlet excited state (Si) after absorption of a

photon from the singlet ground state (So). Excitation of the ground state So to any singlet

excited state Sx leads to the population of the lowest singlet excited state S1 by very fast

radiationless decay (~10-12 -10-13 sec). The excited state S1 can radiatively decay

(fluorescence) S1 So with a rate kf. From S1 there are two possible non-radiative

decay path ways the first being relaxation back to So with a rate kl and the second

intersystem crossing to the lowest energy triplet state T1 with a rate k2. The triplet state

(Ti) can then radiatively decay to So (phosphorescence) with a rate kp. The first non-

radiative decay path way is back to the singlet ground state So with a rate k3.

Alternatively through thermal repopulation or triplet-triplet collisions repopulation of the

singlet excited state (Si) may occur resulting in another non-radiative decay pathway

followed by delayed fluorescence.

Emission from Metalloporphyrins

The insertion of a heavy metal to form a metalloporphyrin causes a decrease in

the fluorescence quantum yield from the expected increase in the rate of intersystem

crossing from the heavy atom effect. The emission properties for regular

metalloporphyrins are described by fluorescent quantum yields in the range 10-3- 0.2

and phosphorescence quantum yields in the 10-4- 0.2 range. Emission from the excited

states for regular porphyrins occurs from the rr-rr* state of the porphyrin ring. The metal

contributes small electronic perturbations resulting in small spectral changes or spin-

orbit perturbations which lead to larger variations in both fluorescent and









phosphorescent quantum yields and triplet lifetimes. Like free-base porphyrins the

regular metalloporphyrins give normal fluorescence spectra with two bands labeled

Q(0,0) and Q(1,0). An example of this type of porphyrin and emission is depicted in

Figure 1-17 by ZnTPP.

1.2

w 1.0

c 0.8
o
E 0.6

S0.4

E 0.2
z
0.0--
500 600 700 800 900
Wavelength (nm)

Figure 1-17. Examples of metalloporphyrin emission in toluene for ZnTPP (red) and Pt-
TPP (purple) excited at the Soret band.

Platinum porphyrins are an example of an irregular metalloporphyrin giving hypso-

type absorption spectra. The insertion of platinum increases the rate of ISC such that

phosphorescence radiativee decay) is the dominant decay pathway. These phosphors

are defined in many cases of having no observable fluorescence or quantum yields of

fluorescence that are < 10-3. This is a result of very high rates of intersystem crossing

and leads to the phosphorescent quantum yields being much higher in the range

between 10-4-0.2 with the triplet lifetimes usually < 3 msec. The phosphorescence for

Pt-TPP which represents an irregular metalloporphyrin is shown in Figure 1-17. The

emission spectrum is red shifted relative to the fluorescence emission from ZnTPP due

to the lower energy of the triplet state. The intensity of Q(0,0) is higher in Pt-TPP than in









ZnTPP, whereas the intensity of the lower energy band corresponding to Q(1,0) is

higher in intensity relative to Q(0,0) in ZnTPP than in Pt-TPP.

Near-IR Light Emitting Diodes: State-of-the-Art

The three major roles of porphyrins in nature were accurately defined by

Gouterman as electron transfer, oxygen transfer, and photosynthesis.40 However, the

research area which encompasses porphyrins has since broaden with scientists finding

new applications in different scientific disciplines and is well reviewed elsewhere.41 One

such application for platinum porphyrins is in light emitting diodes (LEDs) which are

devices fabricated from inorganic or organic materials sandwiched between two

electrodes. Upon application of an electric field these devices emit light. This process is

known as electroluminescence (EL) and discussed further in more detail along with

other aspects of LEDs in the introduction section of Chapter 3.

Pt-OEP was first reported and incorporated into an OLED by Thompson et a/.42' 43

The use of Pt-OEP produced deep red emitting OLEDs with record high efficiencies at

the time. The increase in overall device efficiency was attributed to the use of a

phosphor over a fluorophore which is discussed in greater detail in Chapter 3.

The development of LED devices that exhibit electroluminescence solely in the

near-infrared (NIR) has continued to be a rapidly growing field over the past decade.

The realization of devices with high efficiencies will enable new technology to be

commercialized for use in infrared signaling and displays, telecommunications, and

wound healing.44-47

The earliest reports of near-IR LEDs date back to the early 1970's fabricated from

inorganic materials which yielded low overall device efficiencies. Today over a hundred

publications in the field exist with less than twenty percent reported prior to 2000. The









use of organic materials for electroluminescence was first reported in 1987 by Tang and

Van Slyke.55 This eventually led to the first deep red and near-IR organic LED report

using buckminsterfullerene in 1991 by Katsumi et al.56 Today a variety of materials are

reported for use in near-IR LEDs, but in general the devices still suffer from low

efficiencies. Much work is still needed in the design and synthesis of highly efficient

emitters in the near-IR spectral region for device applications. The majority of reports for

near-IR LED devices have reported external quantum efficiencies (EQE) of less than

one percent. The EQE data and the peak electroluminescence wavelengths for some

recent literature reports representing the highest efficiency devices to date for near-IR

LEDs is summarized in Table 1-1.

Table 1-1. Recent literature reports of near-IR LED devices demonstrating the state-of-
the-art in terms of emission wavelength and device efficiency. 54
Year Molecule Amax (nm) Power Efficiency Ref.
(EQE)
2001 Ln-TPP 977, 1560 -- 0.015%, 0.1% 48
(Ln = Yb3+ or Er3+)
2003 DDD 820 0.1% 49
(Zn porphyrin Trimer)
2005 PPyrPyrPV 800 60 nW/cm2 Low 50
(Copolymer)
2005 PMOPV-TBSV30 800 -- 0.01% 51
(Copolymer)
2005 PFO-SeBSe 10 759 -- 0.20% 52
(Copolymer)
2007 Pt-TPTBP 773 750 pW/cm2 6.3% 53
(Pt-porphyrin) at 12 V
2008 PtPc 966 80 pW/cm2 0.3% at 54
(Pt-Phthalocyanine) at 140 ma/cm2 approx.
1 mA/cm2

Previous work in our group focused on the synthesis and characterization of

lanthanide monoporphyrinate complexes as near-IR emitters for LED applications.48

The lanthanide monoporphyrinate complexes were fabricated into near-IR LEDs by

blending them into conjugated polymers (Figure 1-18). The TPP ligand served as an










antenna to sensitize the narrow near-IR emission from the coordinated lanthanide

metal. However these transitions are weak with photoluminescence quantum yields

generally well below one percent leading to device efficiencies well below half a

percent.

Yb Nd Ho Er



-' iR R C
E
~-J


Ph /
Ph h
Ln= Yb, Er, Nd, H Ln= Nd, Pr .,
8a0 900 1000 1100 1200 1300 1400 1500 1800
Wavelength (nmn)

Figure 1-18. Lanthanide based near-IR emission from lanthanide monoporphyrinate
complexes towards near-IR LED applications.48

Therien and Bazan in 2003 reported near-IR PLEDs using ethyne-bridged zinc

porphyrin fluorophores.49 A zinc porphyrin trimer (DDD) was doped into polymer host

materials and electroluminescence observed at 820 nm. The overall performance of the

device was rather low with an EQE of 0.1%. PLEDs fabricated from near-IR emitting

polymers have been reported.50-52 Conjugated polymers in general usually have lower

PL efficiencies and broad emission profiles. The use of these materials for LED

applications is less than ideal and results in lower device efficiencies.

An alternative to the Lanthanide porphyrin complexes are the rr-extended

porphyrins which have been initially investigated since the 1940's. However use of

these materials towards material science applications has been limited due to the

difficulty in their preparation. The recent advances in the synthesis of rr-extended

porphyrins made by Finikova et al have allowed access to these ideal targets for use in









near-IR LED device applications. The success in fabricating deep red emitting LED

devices using Pt-OEP cements the promise of these materials in this field. Recently

Thompson et al demonstrated the use of a platinum rr-extended porphyrin as a near-IR

phosphor for use in a near-IR LED (Figure 1-19) by incorporating platinum

tetraphenyltetrabenzoporphyrin (Pt-TPTBP) in an Alq3 host matrix. The optimized device

displays an electroluminescence peak in the near-IR region at 772 nm with a record

EQE for this wavelength region of 8.5%. Similarly a near-IR LED based on a platinum

phthalocyanine (Pt-Pc) has also been reported with electroluminescence centered at

966 nm with an EQE of -0.3%.54


10
10- N A .
38- 1 N I v&
.N .I
ii IE IUFTA
S04- 4: SCP 140r, mO

0 .2-
0. E 2 ITO -

500 600 700 800 :900 1000 i 104 t 1 l' 1 10 10'
'aMelenglh (rim) C current Oertsrty I niAm.me)

Figure 1-19. Near-IR OLED device data for Pt-TPTBP doped in to Alq3 reported by
Thompson et al.53 A) Electroluminescence at 772 nm from Pt-TPTBP doped
in Alq3 B) External quantum efficiency of 8.5% and optimized device structure.

rr-Extended Platinum Porphyrins as Near-IR Phosphors

Platinum complexes of rr-extended porphyrins have been demonstrated by

Thompson et al to be ideal targets for application in near-IR LEDs. To the best of our

knowledge only five platinum TBP derivatives have been reported, while no reports exist

for the TNP and TAP systems.53' 57, 58 This is largely due to the difficulty in the

preparation of the platinum complexes in good yield from the free-base porphyrins.











Therefore the development of metallation conditions to provide access to the platinum

complexes of rr-extended porphyrins is imperative and described in Chapter 2. The

novel reaction conditions have allowed access to platinum TNP and TAP systems for

the first time, where this work would otherwise not be possible.

Figure 1-20 outlines the nearly all the known structures for free-base and metallo-

TBPs, where Pt-la and Pt-4b represent two of the known platinum complexes for rr-

extended porphyrins.32' 33, 5862 The other three platinum complexes are derivatives of Pt-

TPTBP were the meso-aryl groups are fluorinated to different degrees.57 The PL spectra


for Pt-la and Pt-4b have maximum emission wavelengths reported at 765 and 745 nm

respectively. The quantum yields of Pt-la and Pt-4b are the highest reported for this

wavelength region of 0.70 and 0.51 respectively. The previously reported free-base and

metallo-TNPs are shown in Figure 1-21.36, 58, 63-65 Completely absent is the report of a

platinum complex, although quite a few palladium complexes have been reported.


CO2Fe



N N

N N

R


R
F
F')


la- R1.4= Ph; M= H, Z, n Pd, Pt 2a: R= Ph; M= H2, Zn Sa; T- n
1b: R1.4= hiophne; M= Zn 2b: R= H: M= H2. Zn, Mg 3b: = C CMe
3c: Y= Br
1c; R14= H; M= H. Pd 3d: Y= OMe
id: R13= H2; R,4= Ph; M= H2, Pd 39: Y= NO0
le- R13= H2; R2,4= 4-NO0CH4; M= H2 M= H2, Cu. Ni, Zn, Pd
if: R1, H-2; R24= 4-B.CIH,,, M= H2
1g- R1,3= H2; R2A= A-MeO2C-GCI-t; M= H2
1 h: R1.= Hz; R;,= 3,5- BuPh; M= HI2

Figure 1-20. Current literature reports for free-base and metallo-TBPs.


Q2C CO,R



4;L R= Me
4b: R= Bu
M= H2, Zn, Pd, Pt Fe


R2

N N
R,
N Ij


" '










The PL spectra reported in the literature for Pd-TNPs are shown to have maximum

wavelengths ranging from 920 -950 nm depending on substitution of the TNP. This is

over a 100 nm red shift compared to the emission of Pd-TBPs. The PL spectra from Pt-

TNPs will likely be blue shifted relative to the Pd-TNPs, following the same trend in

platinum and palladium complexes for porphyrins and TBPs. The quantum yields range

from 2-5% and are lower than the 6.7% reported for a Pd-Ar4TBP derivative. The

quantum yields for Pt-TNPs should be expected to be higher than the Pd-TNPs based

on the observed trend in the Pd-TBP (0.067) and Pt-TBP (0.51) derivatives. This data

suggest that a Pt-TNP derivative will likely have a high PL efficiency for this wavelength

region making it an ideal candidate for near-IR LED applications.












R M ,R M


Y




a: X R Me; M 2 Zn, Pd 8 X H YH M I-b, Zn, Cu, Pdy


b: XH, R= -(CH2)COEt: M Zn, Pd 8b: X= H, Y= 4-MeOC: M= t, Zn. Pd
^^SR no X X

7a: X= H, R= Me; M= H2, Zi, Pd Sa: X= H, Y=H' M= Hz, Zn, Cu, Pd
7b": X- H, R- -(CH2 3CCOEt: M! H2, Zn, Pd Ob: X= H, Y= 4-MeOW a M= Ih, 2n. Pd
7b: X= Ph, R= Me: M= Hz, Zn, Pd Sc; X= OMe, Y= H; M= I2 Zn, Pd
7c: Xr nwiryl, R= Me. M= Hz 8d; X= OMe, Y= 4-M C, M= H Zn, Pd

Figure 1-21. Current literature reports for free-base and metallo-TNPs.









Recent literature reports for TAPs suggest that PL from a Pt-TAP should be

centered beyond a 1000 nm. To date there are only a couple reports on PL from

TAPs.38, 66 Ono et al report the fluorescence and quantum yield data for ZnTAP

derivatives. The reported emission maxima are ~820 nm. There is only one known

report of a phosphorescent TAP reported by Cheprakov et al. They report a Pd-TAP

porphyrin with the PL centered at 1107 nm and a phosphorescence quantum yield of

less than 0.5%. There are no reports for a Pt-TAP and the photophysical properties

remain unknown. However, the preparation of a Pt-TAP derivative will allow access to a

new wavelength region in the near-IR.












Ba: R= -Ha; M= Zn
9b: R= Pht; M- Zn
9: R-- 3,5,-BuPh; M = Z
9d; R= 4-MeO2G-PFI; M= H., Zn. Pd


Figure 1-22. Current literature reports for free-base and metallo-TAPs.

Objective of Present Study

The objective of the present study is to expand the known series of rr-extended

platinum porphyrins beyond the TBP system to the TNP and TAP systems. A novel

metallation procedure is reported herein providing access to the platinum complexes in

high yield for the first time. The photophysics of these materials will be reported for the

first time in both solution and in thin films. The present study will also aim to optimize









the porphyrin macrocycle through chemical modification by looking at the effects on

solution and film photophysical and device properties of different substituents and

substitution pattern of the rr-extended platinum porphyrins in an attempt to increase the

device efficiencies. This optimization should lead to higher phosphorescence quantum

yields and reduced aggregation in a solid state matrix. Devices will be fabricated by two

methods the first being from materials that are vapor deposited (sublimation) onto a

substrate termed organic light emitting diodes (OLED) devices. The second

methodology uses solution processing to form thin films of conjugated polymers doped

with the platinum rr-extended porphyrins by spin coating the materials onto the device

substrate referred to as PLED devices. The overall goals for device efficiencies (EQE)

are to produce an OLED device with electroluminescence solely in the near-IR spectral

region operating at external quantum efficiency greater than 10%. The efficiency goals

for a PLED device are to fabricate a device that operates at an overall efficiency greater

than 1% with electroluminescence solely in the near-IR.









CHAPTER 2
SYNTHESIS OF nr-EXTENDED PLATINUM PORPHYRINS

Introduction

The advances in synthetic methodology from the recently developed

dihydroisoindole technique for preparing rr-extended porphyrins has provided

researchers with access to materials once thought inaccessible. Thompson's group

recently demonstrated a highly efficient near-IR OLED device using Pt-TPTBP as the

near-IR phosphor.53' 67 This work along with the recent reports of the synthesis of TNP

and TAP systems are encouraging for further development of new rr-extended platinum

porphyrins as NIR phosphors. While the free-base porphyrins and a few metal

complexes have been reported for each of these systems, the platinum complexes are

still unknown.36 38 The published absorption and emission data for TBP, TNP and TAP

systems (Figure 2-1) was reviewed in Chapter 1. The increase in conjugation to the

porphyrin macrocycle via additional fused-benzene rings systematically red shifts the

absorption and emission spectra.58




NH N NH N ) NH N
:N H, N HNe



Tetrabenzoporphyrinr Titiariaphtnirij po- r tr Tetraanthroporphyrin
(TBP) "TNP (TAP)

Figure 2-1. General structures for meso-unsubstituted r-extended porphyrins.

The present study presents three novel series of rr-extended platinum porphyrins.

The goal of the first series is aimed at pushing device emission further into the near-IR

by the addition of fused-aromatic rings to the porphyrin macrocycle. The second series









of target TBPs focuses on increasing the solution quantum yield of platinum TBPs by

varying the number of meso-aryl substituents around the porphyrin macrocycle in

attempts to understand the factors that control the emission yield. The third series

presents platinum TBPs designed to increase device efficiencies by chemical

modification to the porphyrin macrocycle incorporating new substituents to either

enhance mixing with the host or by preventing the porphyrin from aggregating. The

target rr-extended platinum porphyrins are outlined in Figure 2-2. Only four of the free-

base porphyrins have been previously reported in the literature (H2TPTBP, H2TPTNP,

H2DPTBP, and H2Ar2TBP).

More importantly only one of the ten subsequent platinum complexes has been

previously reported and studied (Pt-TPTBP). Demonstrating the degree of which the

platinum complexes for rr-extended porphyrins have been under studied. The recent

synthetic methodology has allowed the preparation of the free-base porphyrins while the

synthesis and characterization of the platinum complexes has been absent from the

literature due to the difficulty in their preparation. The following series of target n-

extended platinum porphyrins has been prepared in efforts to characterize the

photophysical properties of these novel phosphors in most cases for the first time.

The first series of target rr-extended platinum porphyrins are outlined in Figure 2-2.

The series is aimed at the preparation of platinum porphyrins with longer emission

wavelengths across the series from Pt-TPTBP to Pt-Ar4TAP. The solution

phosphorescence of Pt-TPTBP has been reported at 773 nm. The emission wavelength

can be further shifted by the preparation of Pt-TPTNP. Recently Finikova et al reported

the phosphorescence of Pd-Ar4TNPs beyond 900 nm and noted that substitution with









eight methoxy-substituents further red shifted the emission to 957 nm.36 This makes Pt-

TPTNP and Pt-Ar4TNP(OMe)8 attractive candidates for NIR LEDs with expected

emission wavelengths beyond 900 nm. Later Yakutkin et al reported the synthesis of

Pd-Ar4TAP derivative and measured the phosphorescence at 1107 nm. The synthesis

of Pt-Ar4TAP would likely provide access to emission beyond 1000 nm. The platinum

complexes for TNP and TAP systems have not been reported in the literature and thus

the photophysical properties remain unknown to date.

The second series of target platinum TBPs is aimed at increasing the solution

quantum yield across the series from Pt-TPTBP to Pt-Ar2TBP. The solution quantum

yields of Pt-TPP (0.07) and Pt-OEP (0.45) have been well studied.43' 68 The large

difference in quantum yields is attributed to the increased planarity of Pt-OEP. The

effects of the number of meso-aryl substituents on the structural and photophysical

properties in the TBP system was recently studied for a series of free-base and Pd-

TBPs.61 The quantum yield for Pd-Ph2TBP is reported to be twice that of Pd-Ph4TBP

due to increased planarity of the TBP macrocycle. The proposed series of tetra-aryl and

5,15-diaryl platinum TBPs are outlined in Figure 2-2. It is expected that the solution

quantum yields for Pt-DPTBP and Pt-Ar2TBP should follow the reported trend for Pd-

TBPs likely leading to significantly higher quantum yields and device efficiencies.

The past decade has seen a surge in the complexity of the fluorophores and

phosphors synthesized for use in LEDs. The early work was focused on finding

materials that displayed electroluminescence at specific regions in the visible (blue,

green, and red) with high quantum yields. However despite the advances made in the










field quenching of the emitting species from intermolecular interactions or poor carrier

mobility within the device matrix remains a problem.69


Series I

I OMe MeO


SNi MNt h N- NN
SM,4 M




Ar = 3,5-di-er-btylphenyI
M Hz : H2TPTBP M H : 2TPTNP M H, : HAr.TNP(OMfl) M H2 : HTPTBP
M = Pt: Pt-TPTBP M= Pt; Pt-TPTMP M = Pt: Pt-Ar, NPIOMBWl M = Pl: Pt-Ar4TAP


Series 2


M H : HzTPTBP M H : H;aArTBP
M Pt: PI-TPTBP M PI: Pt-Ar4TBP


M H: HDPTBP M H : HzArTDBP
M Pt: Pt-DPTBP M Pt : Pt-Ar2TBP


I R'R 'rRN \
R
R = 9,9-dihexylluorene R = 4-ter-butylphenyl
M = H 2 HArF4TBP M I : HHTAr2TBP M = H,: HiArjQPrTBP
M = Pt: Pt-ArFITBP M = Pt: Pt-TAr2TBP M Pt Pt-Ar OPrTBP

Figure 2-2. Target free-base and platinum porphyrins towards new near-IR phosphors.

The use of dendrimer encapsulated phosphors has proven effective in reducing

aggregation problems.70-73 The area of porphyrin dendrimers is a growing field with the


Series 3


;11









new materials being applied to a variety of applications.74 Fluorescent porphyrin

dendrimer systems have been reported for use in LED device applications with

improvements reported in device efficiencies over other fluorescent porphyrin

systems.75 Only one platinum porphyrin based dendrimer system has been reported for

LED applications displaying higher device efficiencies than those reported for pure Pt-

OEP or PVK: Pt-OEP devices.76 Unfortunately the synthesis of dendrimers is lengthy

and often accompanied by difficult purification making targets of this nature impractical.

Recently porphyrins have been reported with bulky meso-aryl substituents that in effect

create the desired dye encapsulation obtained by a porphyrin dendrimer system noted

by an increase in the solution quantum yield.77 The fluorescence quantum yields for

some reported TPP derivatives are reported to be twice that of TPP from the reduction

in porphyrin aggregation in solution. The target Pt-TBP structures in series 3 are aimed

at reducing aggregation effects or increasing host compatibility in the device matrix

(Figure 2-2). The structures are based on recent literature reports for similar porphyrin

systems.77-79

In the work described in the present chapter, we report the design and synthesis

of three novel series of rr-extended platinum porphyrins. The free-base porphyrins have

been prepared using the dihydroisoindole method. The platinum porphyrins have been

prepared from a novel metallation procedure developed herein. The materials have

been characterized by 1H and 13C NMR and HRMS. The photophysical properties for

each series have been studied and are reported in Chapter 3 along with the

performance for each material as near-IR phosphors in near-IR LEDs.









Synthesis of Aromatic Aldehydes for rr-Extended Porphyrins

The synthetic scheme for the target aromatic aldehydes is outlined below in Figure

2-3 along with commercially available benzaldehyde (1). Aldehyde 3 was prepared

starting from commercially available 2 which was brominated with NBS and then

subjected to oxidation/hydrolysis with examine to produce 3 in moderate yield following

a previously reported method.80



Br a
6 46% Br B 77"- r. 61%
1 23 4 y


Br< O 7Br7% O ^
CJ ,13 C 1H,1 g


Figure 2-3. Synthetic scheme for aromatic aldehydes towards meso-aryl substituted rr-
extended porphyrins. Reagents and conditions: i) NBS, CCI4, 12 h reflux,
examine, MeOH, H20, reflux 4 h; ii) n-BuLi, DMF, ether, -78C, 30 min; iii)
Pd(PPh3)4, Na2CO3,4-tBuPhB(OH)2, PhMe, THF, H20, 100C, 120 h; iv) Br-
Hexyl, NaOH, DMSO, H20, 80C overnight; v) Pd(PPh3)4, Na2CO3,4-
formylPhB(OH)2, THF, H20, 80C, overnight

Aldehyde 6 was prepared in analogous manner to the reported 3,5-

diphenylbenzaldhyde.77 Treating 1,3,5-tribromobenzene (4) with one equivalent of n-

BuLi followed by the addition of DMF gave 5 in good yield.81 Compound 5 was then

introduced to Suzuki coupling with 4-tert-butylphenylboronic acid yielding aldehyde 6 in

good yield.77 The preparation of 9 followed a previously reported method.82 The

alkylation of 2-bromo-fluorene was performed by a previously reported method to give 8

in excellent yield.83 Compound 8 was introduced to a Suzuki coupling with 4-

formylbenzeneboronic acid to give aldehyde 9 in good yield.









Synthesis of Pyrroles for rr-Extended Porphyrins

The synthesis of six of the eight free base TBPs share a common intermediate in

2-ethoxycarbonyl-4,7-dihydro-2H-isoindole (18a) which was prepared according to a

previously reported method (Figure 2-4).37 The other two TBP derivatives required a

substituted butadiene to access the desired pyrroles.


EIO0P-DEt
EOPOEt
0 14H

R 62% 73%
12 R = Pr-n 0 H
EtOFP OEt 10
11 R R

311 0 11 Vii
67% %11 R'" V WE
,, a. SiMe- 16 13:R=H 17 R=H(74%) H
14 12: R R- n 17b: R Pr-n (BB%) 18S: R= H (80%)
18b: R = Pr-n (52%}

Figure 2-4. Synthetic scheme for benzopyrroles 18a-b towards TBPs. Reagents and
conditions: i) HCI, 250C, 1h; ii) (EtO)2P(O)CI, pyridine, 0C, 2 h; iii) THF, Cul,
0C-25C, overnight; iv) DCM, AICI3, TsCI, 24 h, 25 C; v) MeOH, NaF in
H20, 0C-25C, 1.5 h; vi) 13 neat 250C, 12 PhMe 1300C, 48 h; vii) THF,
tBuOK, CNCH2CO2Et, 0C-25C, 4 h.

The 2,3-substituted butadiene 12 was prepared according to a previously reported

method. Following a published procedure compound 11 was prepared by treating

commercially available 10 with diethyl chlorophosphate in the presence of pyridine to

give 11 in good yield. The addition of an alkyl Grignard reagent to 11 gave the desired

2,3-substituted butadiene 12 in moderate yield. The Diels-Alder adducts 17a-b where

prepared from butadienes 12 and 13. Starting from commercially available 14 treated

with a solution of AICI3 and TsCI in dry DCM to afford the alkylation adduct 15 in good

yield.84, 85 Compound 15 was converted to ethynyl p-tolyl sulfone (16) following a

published procedure by deprotecting 15 with aqueous sodium fluoride in methanol to

give 16 nearly quantitatively.86 The Diels-Alder adduct 17a was obtained by reacting 16









in neat 1,3-butadiene (13) to give 17a in good yield following a previously reported

method. Similarly 17b was prepared from 16 and 12from a modified literature method to

give 17b in good yield. Dropwise addition of the vinylic sulfones 17a-b to a one

equivalent tBuOK and ethyl isocyanoacetate mixture in dry THF in a modified Barton-

Zard synthesis gave benzopyrroles 18a-b in good yield.



S87% 65%
a SO0Ph -N C't
20 21

0 0 OMe OMe MeOD D

96%)J 6g4% C 70%
0 0 OMe OMe EtO2C
22 23 24 25 26

Figure 2-5. Synthetic scheme for naphthopyrroles 21 and 26 towards TNPs. Reagents
and conditions: i) PhSCI, DCM, 0C, 1 h, m-CPBA, 0C-25C, 1 h; ii) THF,
tBuOK CNCH2CO2Et, 0C-reflux, 1 h; iii) AcOH, 25C, 24 h; iv) Me2SO4,
K2C03, acetone, reflux 40 h; v) PhSCI, DCM, 0C-250C, 2 h, m-CPBA, 0C-
250C, 1 h; vi) THF, tBuOK CNCH2CO2Et, 0C-reflux, 1 h.

The synthesis of naphthopyrroles 21 and 26 have been previously reported and is

outlined in Figure 2-5.36 Pyrroles 21 and 26 were similarly prepared from commercially

available 1,4-dihydronaphthalene (19) and 5,8-dimethoxy-derivative 23. Starting from

commercially available 1,3-butadiene and 1,4-benzoquione (22) in acetic acid at room

temperature gave the Diels-Alder adduct 23 in a moderate yield.87 Compound 23 was

treated with potassium carbonate and dimethyl sulfate in refluxing acetone to give 24 in

an excellent yield.87 The a-chlorosulfones 20 and 24 were prepared from the dropwise

addition of phenylsulfenyl chloride (PhSCI) in dry DCM to 19 and 23 followed by

oxidation with m-CPBA which gave the a-chlorosulfones 20 and 24 in good yield. The

pyrrole esters 21 and 26 were obtained in good yields and prepared analogously to 18a









from a modified Barton-Zard synthesis requiring an extra equivalent of base to form the

vinylic sulfone in situ from the protected a-chlorosulfone.

The anthropyrrole precursors 32 and 38 that provide access to the TAP system

were prepared from previously reported literature methods.38' 66 The key intermediates

for the pyrrole synthesis are 1,4-dihydroanthracene (35) and bicyclic-precusor 30.

Compound 30 was prepared starting from 1,4-naphthoquione (27) and 1,3-

cyclohexadiene in refluxing ethanol to give the Diels-Alder adduct 28 in a good yield.88

The reduction of dione 28 in anhydrous methanol with sodium borohydride smoothly

gave the diol 29 in excellent yield.89



HOill _
S% 74% 59% 3 CO,Ei
2A 29 30 H31
%232




=- 5 S r^Ph SQzPh
33 34 35 36 37 38

Figure 2-6. Synthetic scheme for anthropyrroles 32 and 38 towards TAPs. Reagents
and conditions: i) EtOH, 3 h, reflux; ii) MeOH, NaBH4, 0C, 2h; iii) Pyridine,
TsCI, 48 h, 25C; iv) PhSCI, DCM, -78C-25C, 4 h, m-CPBA, 0C-25C, 18
h; v) THF, tBuOK, CNCH2CO2Et, 0C-250C, 18 h; vi) Pyridine, 3-sulfolene,
NaHCO3, 120C, 70 h; vii) EtOH, HCI, reflux, 24 h; viii) PhSCI, DCM, -780C-
25C, overnight, m-CPBA, 0C-250C, 48 h; ix) DCM, DBU, 25C, 1 h; x) THF,
tBuOK CNCH2CO2Et, 0C-25C, overnight.

The dehydration of 29 with excess tosyl chloride in dry pyridine yielded 30 in good

yield.90, 91 Key intermediate 35 was obtained starting from 33 which was prepared from

a literature procedure from benzyne and furan.92 93 Compound 33 was treated with 3-

sulfolene while heating in pyridine to yield the Diels-Alder adduct 34 in good yield.









Compound 34 was then introduced to refluxing ethanol and HCI to give 35 in a good

yield. The reported method of preparing 36 using Oxone as the oxidant failed. The a-

chlorosulfones 31 and 36 were obtained from a modified procedure for 20.66 The

dropwise addition of PhSCI in dry DCM to 30 and 35 at -78C followed by oxidation with

m-CPBA for 18 to 48 hours gave 31 and 36 in good yields.

Pyrrole esters 32 and 38 could be prepared directly from a-chlorosulfones 31 and

36 forming the vinylic sulfone in situ to give the anthropyrroles in moderate yield.

Alternatively 38 could also be prepared in a similar yield from the deprotection of 36 to

allylic sulfone 37 with DBU. Allylic sulfones have previously been demonstrated as

suitable substrates in the modified Barton-Zard synthesis over vinylic sulfones.36 The

modification requires a small excess of strong base to induce the allylic-vinylic sulfone

isomerization.

Synthesis of Symmetrical rr-Extended Porphyrins

Deprotection of Pyrrole Esters

The major advantage of the dihydroisoindole method is that the desired rr-

extended porphyrins are prepared under Lindsey conditions. This requires cleavage of

the ester from the pyrrole-esters obtained from the modified Barton-Zard reaction. Two

methods have been reported for the ester-cleavage of the pyrroles. Pyrrole esters

prepared from tert-butyl isocyanoacetate can be deprotected from TFA at room

temperature.59

However pyrrole-esters obtained from ethyl isocyanoacetate are heated in

ethylene glycol in the presence of excess KOH to provide the unprotected pyrroles.37

The latter method was used to smoothly yield all the precursor pyrroles in good yields

and is outlined in Figure 2-7. Due to instability of the unprotected pyrroles, they are not










subjected to purification to analytical standards and are subjected to minimal purification

prior to immediate use in a porphyrin synthesis.



COG2Et %
HH
IBa BP





M LN N M
H H H H
NP NP2 AP AP2
86% 61% B7% 82%

Figure 2-7. Synthetic scheme for the deprotection of pyrrole esters. Reagents and
conditions: i) Ethylene glycol, KOH, 170C, 1 h.

Synthesis of Tetraaryltetrabenzoporphyrins

Tetraaryltetrabenzoporphyrins 39a-c were prepared from pyrrole BP and the

respective aromatic aldehydes (1,3,9) following the reported method for 39a and as

outlined in Figure 2-8.37 Pyrrole BP with one equivalent of aromatic aldehyde (1,3,9) in

DCM in the presence of Lewis acid catalyst yielded the H2Ar4octahydroTBPs which

were not isolated and further oxidized to the target TBPs by refluxing in toluene with

DDQ in good yields.

Ar


+ Ar -- N Ar
SNAr H
BP

39a: Ar = phenyl (29%)
39h: Ar = 3,Sdl-Lert-bulylphenyl (20%)
39c: Ar= 4-i .'-line r -filoreri li-pherIil (17%)

Figure 2-8. Synthetic scheme for H2Ar4TBPs. Reagents and conditions: i) DCM,
BF3-O(Et)2, DDQ, 4 h, PhMe, DDQ, reflux 1 h.









The target TBPs were purified via column chromatography and exhibited good

solubility in common organic solvents (DCM, CHCI3, THF). The materials were further

purified by multiple precipitations from a good solvent (DCM, CHCI3) into excess

methanol under vigorous stirring. Compounds 39a-c were characterized by 1H and 13C

NMR and mass spectrometry.

Synthesis of Tetraaryltetranaphthoporphyrins

The synthesis of TNPs 40a and 40b from the respective naphthopyrroles NP and

NP2 followed the reported method for 39a as outlined in Figure 2-9.36 Under Lindsey

conditions pyrroles NP and NP2 were reacted with one equivalent of aromatic

aldehydes (1,3) gave the target TNPs 40a and 40b in good yields. In the synthesis of

H2Ar4TBP a tetraaryloctahydrotetrabenzoporphyrin could be isolated and then oxidized

with DDQ. However in the present synthesis of H2Ar4TNPs an analogous intermediate

was not isolated. The H2Ar4TNPs formed after the addition of DDQ and stirring at room

temperature overnight or a one hour reflux in DCM. The target compounds were purified

by chromatography and precipitation into methanol. Compounds 40a and 40b were both

characterized by 1H and 13C NMR and mass spectrometry and exhibited good solubility

in common organic solvents (DCM, CHCI3, THF).

x x


+0 NH N A
S Ar N HN
(t,3}
NP X=H r
NP2 X=OMe
X X
40a: Ar = phnyl; X= H .*-(r
40b: Ar 3,5-di-tert-butylpheryl; X = OMe (16%}

Figure 2-9. Synthetic scheme for H2Ar4TNPs. Reagents and conditions: i) Dry DCM,
BF3O(Et)2, 1.5 h, DDQ, reflux 1 h.









Synthesis of Tetraryltetraanthroporphyrins

Recently two methods have been reported for the preparation of H2Ar4TAPs as

outlined in Figure 2-10.38 66 The methods differ in that the one reported by Ono et al

from AP uses a solid state high temperature retro-Diels-Alder reaction to quantitatively

yield 42 after intermediate porphyrin 41 has been isolated. Initial attempts to reproduce

this method failed leading to incomplete reaction mixtures. However, small milligram

quantities of 42 can be obtained from 41.The method was abandoned due to this

difficulty and the unlikely hood of being able to scale the reaction up beyond 10-20

milligrams.



A Ar Ar

NH N Ar NH N
-+ H w I Ar +
51% N HN N HN HO
A r 3 Ar Ar 3
AP A1b bP2

41: At = 3,5-dl-tart-butylphe ryl 42: Ar 3,5-di-tert-butylphenyl


Figure 2-10. Synthetic scheme for H2Ar4TAP. Reagents and conditions: i) DCM,
BF3-O(Et)2, 18 h, DDQ, r.t., 1 h; ii) High vacuum, 290C, 2 h; iii) DCM,
BF3O(Et)2, 1 h, DDQ, r.t., 1 h.

Alternatively the use of the dihydroisoindole method provides access to the

Ar4TAPs at room temperature forming 42 almost instantly after the addition of DDQ to

the reaction mixture. However as noted by both literature reports, the free-base and

metal complexes of the TAPs are unstable towards oxygen in the presence of room

light. Extreme caution must be taken in the handling and synthesis of these materials by

either protecting the material from light or working under inert atmospheres. TAP (42)









was prepared from pyrrole AP2 as reported in the literature in a good yield (Figure 2-

10). The material was purified by column chromatography and then stored under inert

atmosphere and further characterized by 1H and 13C NMR and mass spectrometry.

Synthesis of 5,15-Diaryltetrabenzoporphyrins

The interest in 5,15-diaryltetrabenzoporphyrins was outlined in the beginning of

this chapter. The synthesis of 5,15-diarylporphyrins from meso-unsubstituted

dipyrromethanes were reported by Treibs et al in 1968.94 Other methodologies were

reported by MacDonald and Baldwin et al from meso-aryl substituted dipyrromethanes

for the preparation of 5,15-diarylporphyrins.95-97 Recently the synthesis of 5,15-

diaryltetrabenzoporphyrins was reported by Filatov et al from meso-unsubstituted

dipyrromethane 44a and aromatic aldehydes.59 The synthesis is outlined in Figure 2-11,

starting from pyrrole-esters 18a-b with one half equivalent of dimethoxy methane in the

presence of acid catalyst meso-unsubstituted dipyrromethanes 43a-b were obtained in

good yield from the previously reported method.


Ar
R R R Ar R
RR ,COEt
i NH U NH N
CNH NH Ar N HN
C2E1 o (E,3,9)
R 2 R Ar R
182 R=H R R R R
18b: R Pr-n
43a: R = H 85%) 44a- R =H -.1"; 45a: Ar = phenyl, R = H (3%)
43b: R = Pr-n (50%) 44b: R = Pr-n (76%) 45b: Ar = 3,5-dl-tar-buylphenyl, R = H :-'- .:
45,; Ar = 3,5-(4-terf-butylphenyl}-pheyf R = H .-.-
45d: Ar = 35-di-tert-buylphenyl, R Pr-ri (1B%)

Figure 2-11. Synthetic scheme for H2Ar2TBPs. Reagents and conditions: i) AcOH,
TsOH, CH2(OMe)2, 25C, 24 h; ii) Ethylene glycol, KOH, 170C, 1 h; iii) DCM,
TFA, 25C, 18 h, DDQ, PhMe, DDQ, reflux, 1 h.

Compounds 44a-b was prepared in a parallel manner to pyrrole BP by heating in

ethylene glycol with KOH. Similar to BP, compounds 44a-b were not subjected to









extensive purification and used immediately in a porphyrins synthesis. The 5,15-

diaryltetrabenzoporphyrins were obtained by condensing 44a-b with one equivalent of

aromatic aldehyde (1,3,6) in the presence of a catalytic amount of TFA followed by the

addition of DDQ. The H2Ar2TBPs (45a-d) were obtained in good yields after adding the

required additional equivalents of DDQ in refluxing toluene to complete the oxidative

aromatization. Compounds 45a-d were purified by column chromatography and from

multiple precipitations into methanol from a good solvent. The overall the solubility of

compounds 45b-d was good in common organic solvents, except for 45a which

exhibited low solubility. The materials were characterized by 1H and 13C NMR and mass

spectrometry with 45a-b having identical data to the previous literature reports.37 59

Synthesis of rr-Extended Platinum Porphyrins

The classical conditions for the preparation of platinum (II) porphyrins involves

excess molar equivalents of PtCI2 in refluxing benzonitrile (> 1900C) with the free base

porphyrin. The benzonitrile and PtCI2 form a complex that increases the solubility of the

platinum reagent. However despite the increase in solubility the reaction often precedes

slowly requiring long reaction times. The addition of the metal to the porphyrin center

increases the symmetry of the porphyrin changing the absorption spectra. Therefore the

metallation reaction is often followed by UV-vis spectroscopy by the disappearance of

the Soret and Q-band for the free-base porphyrin.

Thompson et al recently reported Pt-TPTBP and prepared the platinum complex

from PtCI2 and benzonitrile prior to oxidation with DDQ to form the TBP ring.53 This

represents one of the few reports for a platinum rr-extended porphyrin report to date.

The oxidation step with the precursor platinum porphyrin gave Pt-TPTBP in a low yield

(30%). The initial attempts to prepare Pt-TPTNP (Pt-40a) from PtCI2 and benzonitrile









(200C) were followed by UV-Vis spectroscopy (Figure 2-12A). The reaction was

followed over five hours with no detectable amounts of Pt-40a in the UV-vis spectrum

for the reaction mixture represented by the black, red and blue traces in Figure 2-12A.

Additionally small amounts of Pt-40a could be detected in the UV-Vis spectrum after

heating at higher temperatures (>2300C) for prolonged periods of time making these

conditions unpractical due to the decomposition of 40a.


1.0
A 20 minutes
0.8 2 hours
0 5 hours
-1. 0.6
o 0.4
< 0.2
0.0 .
or 4 1.0
.B 0 minutes
C 0.8 30 minutes
E Overnight
o 0.6
0.4
0.2
0.0 .
300 400 500 600 700 800 900

Wavelength (nm)

Figure 2-12. Platinum metallation reaction for Pt-TPTNP (Pt-40a) followed by UV-vis
spectroscopy. A) H2TPTNP and PtC12 in PhCN at 2000C followed over 5 h by
UV-vis spectroscopy. B) H2TPTNP and [Pt4(OAc)8]-2HOAc in PhCN at 1800C
followed overnight by UV-vis spectroscopy.

However, it is known that metal(ll) acetates are more reactive than the respective

metal(ll) halogen species. Platinum(ll) acetate is not commercially available and only

two reports exist for its preparation but is readily prepared from silver acetate in

refluxing acetic acid under and inert atmosphere.98 The reaction of platinum(ll) acetate

with 40a in benzonitrile (1800C) immediately shows the formation of the Pt-40a after 30










minutes (red trace) from the appearance of a new blue shifted Soret and Q-band. The

UV-vis spectrum of the reaction mixture after heating overnight or five hours (blue trace)

shows the complete disappearance of the free-base Soret and Q-band (Figure 2-12B).

This represents a unique method for preparing rr-extended platinum porphyrins at lower

temperatures and shorter reaction times in higher yields. The novel reaction conditions

have allowed the preparation of platinum complexes for the TNP and TAP systems for

the first time, while also providing an improved yield in the synthesis of platinum TBPs

over previous literature methods. The target rr-extended platinum porphyrins (Figure 2-

13) were all prepared in an analogous manner to Pt-40a. The materials were subjected

to vacuum distillation to remove the high boiling solvent followed by chromatography

and multiple precipitations to remove small amounts of free-base porphyrins prior to

characterization by 1H and 13C NMR and HRMS.

R R R R





R R R R
3a-ct-3 : A = afwI, Pt.N1b: Ar = 54Iphenyl. R = R
Pt-39b. Ar = 3,5-,l{ lh- li:phsn i5l Pt-5t: Ar = S.s-dl-.er-ulylpheny1. R = H
Pt-39cL ,Al = 4-,9,Et-cllhfl] l-nr iirfl]hyl)-pna l PF-S Ar= '. '.-i-ier, .. ri-,,Jrl.ii,,li.1ph .- I R = H
Pt-4d: Ar = 3,5-di-er-butylph R = Pr-n



X X



i X Ar Ar

40a-b Pl4Oa: Ar = phenyl; X = H
PM.4t; Ar = 3.5-di-kfrt-butylptworr; K = OMe Pt142: Ar = 3,5-dl-Iert-bulliphenyl

Figure 2-13. Synthetic scheme for rr-extended platinum porphyrins. Reagents and
conditions: i) [Pt4(OAc)8]-2HOAc, PhCN, 1800C, under anaerobic conditions.









Conclusions

The desired goal of developing 3 series of rr-extended platinum porphyrins was

realized. The free-base rr-extended porphyrins were prepared following previously

reported literature methods. The platinum complexes were prepared from the novel

metallation conditions with platinum acetate developed herein allowing the platinum

complexes for TNPs and TAP to be reported for the first time. Also reported for the first

time are platinum complexes for unsymmetrical 5,15-diaryl TBPs. The synthesis of rr-

extended platinum porphyrins overall are reported in higher yield than previous literature

methods. Access to these new materials has finally allowed for complete

characterization followed by investigation of these materials as near-IR phosphors in

light emitting diode applications.

Experimental

Materials and General Procedures. All chemicals used for synthesis were of

reagent grade and used without further purification unless noted otherwise. Reactions

were carried out under inert atmospheres of argon or nitrogen. Dry solvents were

obtained from a solvent purification system or from standard distillation methods unless

otherwise noted. All glassware was flame or oven dried prior to use unless otherwise

noted. NMR spectra were recorded on a Varian Gemini 300, VXR 300, Mercury 300 or

Varian Inova 500 spectrometer and chemical shifts are reported in ppm relative to

CDCI3 unless otherwise noted. Ethyl isocyanoacetate was purchased from Sigma

Aldrich and vacuum distilled each time prior to use. Solutions of PhSCI were prepared

according to literature methods from N-chlorosuccinimide and thiophenol.34 Platinum

acetate was prepared from a previously reported method.98 Purification by column

chromatography was performed on SiliaFlash silica-gel (mesh 230-400).









3,5-Di-tert-butylbenzaldehyde (3). The title compound was prepared following a

modified literature procedure.80 A solution of 2 (10.00 g, 48.9 mmol) and NBS (18.00 g,

101 mmol) in CCI4 (160 mL) with benzoyl peroxide (80 mg, 0.33 mmol) was refluxed

overnight. The formed precipitated was removed by filtration through celite and the

solvent removed to yield an oil. The crude material was dissolved in mixture of water

(15 mL) and EtOH (15 mL) with hexamethylenetetramine (19.90 g, 142 mmol) and then

heated to reflux for 4 hours. The reaction was diluted with a toluene/ether (1:1, 200 mL)

mixture and then washed with brine (100 ml x 3). The organic layer was dried over

MgSO4 and the solvent removed. The crude material was recrystallized twice from

MeOH to give 4.94 g of the title compound (46%). The material gave identical spectral

data to that previously reported in the literature.8 1H NMR (CDCI3, 300 MHz): 5 = 10.01

(s, 1H), 7.73 (m, 3H), 1.36 (t, 18H).

3,5-Dibromo-benzaldehyde (5). The title compound was prepared following a

modified literature method.81 Compound 4 (3.01 g, 9.6 mmol) in diethyl ether (80 mL)

was cooled to -78C followed by the addition of one equivalent of n-BuLi dropwise (2.5

M, 3.8 mL). The reaction was stirred for 30 minutes then DMF (740 pL, 9.6 mmol) was

added dropwise to the reaction and stirred at -78C for one hour. The vessel was then

placed in an ice bath and stirred for 30 minutes. A 10% HCI solution (100 mL) was

added to quench the reaction followed by CHCI3 (150 mL). The organic layer was

collected and the aqueous layer washed with CHCI3 (80 mL). The organic layers where

combined and dried over MgSO4 and the solvent removed. The crude product was

purified by column chromatography eluting with 10% EtOAc in hexanes to give 1.93 g of

the title compound (77%). Spectral data for the title compound was not reported in the









literature reference.81 H NMR (CDCI3, 300 MHz): 5 = 9.90 (s, 1H), 7.92 (d, 2H), 7.60 (s,

1H); 13C NMR (CDCI3, 75 MHz) 5 = 189.3, 139.7, 139.0, 131.37, 124.1; GC-MS [M+H]+

262.8709, calcd 262.8707.

3,5-Di(4-tert-butylphenyl)benzaldehyde (6). The title compound was prepared

following a modified literature method.77 Compound 5 (1.02 g, 3.9 mmol) and 4-tert-

butylphenyl boronic acid (1.47 g, 8.3 mmol) were dissolved in toluene (75 mL) and THF

(60 mL) with Na2CO3 (1.12 g) and water (9 mL). The solution was purged with argon for

15 minutes followed by the addition of Pd(PPh3)4 (200 mg, 0.2 mmol). The reaction was

stirred and purged with argon for 20 minutes and then heated at 100C for 120 hours.

The solvent was removed and the crude material loaded on silica eluting with a

hexane/DCM mixture (70/30). The fractions were combined and the solvent removed.

The material was dissolved in minimum of DCM and diluted with MeOH precipitating

865 mg of the title compound (61%). The title compound is reported in the literature with

no experimental or spectral data.99 1H NMR (CDCI3, 300 MHz): 5 = 10.14 (s, 1H), 8.05

(m, 3H), 7.63 (d, 4H), 7.53 (d, 4H); 13C NMR (CDCI3, 75 MHz) 5 = 192.7, 151.4, 142.7,

137.6, 137.1, 131.7, 127.1, 127.0, 126.2, 34.8, 31.5; DART-MS [M+H] 371.2369, calcd

371.2369.

2-Bromo-9,9-dihexylfluorene (8). The title compound was prepared following a

modified literature method.83 A mixture of 7 (2.00 g, 8.2 mmol) and bromohexane (10

mL, 70.8 mmol) with NaOH (2.8 g, 70 mmol) and Bu4NCI in DMSO (20 mL) and water (3

mL) was stirred. The reaction was heated at 80C overnight and then poured into

excess ethyl acetate (200 mL). The precipitated NaOH was filtered off and the organic

layer washed with 2N HCI solution (100 mL) and brine (100 mL). The organic layer was









collected and dried over MgSO4. The solvent was removed and the crude product

purified by column chromatography eluting with hexane to yield 3.14 g of the title

compound (93%). The material gave identical spectral data to that previously reported

in the literature.83 1H NMR (CDCl3, 300 MHz): 5 = 7.68-7.64 (m, 1H), 7.57-7.54 (m, 1H),

7.46-7.43 (m, 2H), 7.33-7.31 (m, 3H), 1.97-1.90 (m, 4H), 1.15-1.03 (m, 12H), 0.79 (t,

6H), 0.62-0.58 (m, 4H).

4-(9,9-dihexyl-fluorenyl)-benzaldehyde (9). The title compound was prepared

following a modified literature method.82 A solution of 8 (1.10 g, 2.7 mmol) and 4-

formylbenzene boronic acid (438 mg, 2.9 mmol) with Na2CO3 (2.96 g) in THF (20 mL)

and water (15 mL) mixture was purged with argon for 30 minutes. Then Pd(PPh3)4 (15

mg, 12.9 pmol) was added and the solution stirred and purged with argon for 15

minutes prior to heating at 80C overnight. The reaction was cooled to room

temperature and then diluted with DCM (100 mL). The organic layer was washed with

saturated aqueous NH4CI solution (100 mL) and then dried over MgSO4. The solvent

was removed and the crude material purified by column chromatography eluting with

45% hexane in DCM to give 900 mg of the title compound (77%). The material gave

identical spectral data to that previously reported in the literature.82 1H NMR (CDCI3,

300 MHz): 5 = 10.1 (s, 1H), 7.98 (d, 2H), 7.84 (d, 2H), 7.80-7.77 (m, 1H), 7.57-7.72 (m,

1H), 7.64-7.61 (m, 1H), 7.59 (m, 1H), 7.35 (m, 3H), 2.01 (m, 4H), 1.05 (m, 12H), 0.75 (t,

6H), 0.68-0.62 (m, 4H).

2-Butyne-1,4-diyl tetraethyl ester phosphoric acid (11). The title compound

was prepared following a modified literature method.100 In dry pyridine (25 mL)

compound 10 (5.76 g, 66.9 mmol) under an argon atmosphere was cooled to 0C









followed by the dropwise addition of diethyl chlorophosphate (25 g, 144.9 mmol). The

reaction was stirred for 2 hours at 0C and then diluted with water (125 mL). The

mixture was washed with ether (3 x 70 mL) and the combined organic layers dried over

Na2SO4. The solvent was removed to give 16.0 g of the title compound (73%). The

material was pure enough for the subsequent Grignard reaction and gave identical

spectral data to that previously reported in the literature.100 1H NMR (CDCI3, 300 MHz):

5 = 4.71 (d, 4H), 4.13 (dq, 8H), 1.34 (t, 12H).

2,3-Dipropyl-1,3-butadiene (12). The title compound was prepared following a

modified literature method.100 The Grignard reagent was prepared from 1-

bromopropane (5.15 g, 41.8 mmol) and Mg (1.12 g, 41.8 mmol) turnings in dry THF (60

mL) in a conventional manner. The solution was cooled to 0C followed by the dropwise

addition of 11 (5.00 g, 13.9 mmol) in dry THF (30 mL). The reaction was warmed to

room temperature and stirred overnight. Water (300 mL) was added to quench the

reaction. The formed precipitate was filtered off and then washed with pentane (150

mL). The aqueous and organic layers were collected and separated. The aqueous layer

was washed with pentane (4 x 80 mL). The organic layers combined and dried over

Na2SO4 and the solvent removed under reduced pressure yielding 1.27 g of the title

compound (62%). The material gave identical spectral data to that previously reported

in the literature.100 1H NMR (CDCl3, 300 MHz): 5 = 5.06 (s, 2H), 4.90 (s, 2H), 2.21 (t,

4H), 1.48 (sex, 4H), 0.91 (t, 6H).

p-Tolyl-[ 2-(trimethylsilyl)ethynyl]-sulfone (15). The title compound was

prepared following a modified literature method.84 A solution of AICI3 (9.4 g, 70.5 mmol)

in dry DCM (40 mL) was cannula transferred to TsCI (13.43 g, 70.4 mmol) in DCM (30









mL) and stirred under N2 atmosphere turning orange in color. A separate solution of 14

in DCM (40 mL) was cooled to 0C in an ice bath. The mixture of AIC13/TsCI was

transferred to the alkyne solution over a period of 10 minutes in small portions. The ice

bath was removed and the reaction stirred overnight at room temperature. The mixture

was poured into ice water (400 g) and the organic layer separated and collected. The

aqueous layer was washed with DCM (3 x 50 mL). The combined organic layers were

dried over MgSO4 and the solvent removed. The crude material was extracted with hot

hexanes and upon cooling yielded 10.01 g of the title compound (67%). The material

gave identical spectral data to that previously reported in the literature.85 1H NMR

(CDCl3, 300 MHz): 5 = 7.90-7.89 (m, 2H), 7.38-7.35 (m, 2H), 2.46 (s, 3H), 0.21 (s, 9H).

Ethynyl p-tolyl sulfone (16). The title compound was prepared following a

modified literature method.86 A solution of 15 (8.01 g, 31.7 mmol) purged with argon in

MeOH (65 mL) was cooled to 0C. The cooled solution was treated dropwise with NaF

(2.08 g, 49.5 mmol) in water (35 mL). The reaction was stirred for 90 minutes at 0C

and then diluted with water (100 mL). The organic layer was separated and collected.

The aqueous layer was extracted with ether (3 x 100 mL). The combined organic layers

were washed with water (2 x 100 mL), 10% aqueous NaHCO3 (1 x 100 mL), and brine

(1 x 100 mL). The organic layer was dried over MgSO4 and the solvent removed. The

crude material was recrystallized from hexanes to yield 5.70 g of the title compound

(98%). The material gave identical spectral data to that previously reported in the

literature.86 1H NMR (CDCI3, 75 MHz): 5 = 7.91-7.88 (d, 2H), 7.40-7.37 (d, 2H), 3.45 (s,

1H), 2.47 (s, 3H).









1-Tosyl-1,4-cyclohexadiene (17a). The title compound was prepared following

a modified literature method.37 A thick walled 100 mL vessel with 16 (5.01 g, 27.8 mmol)

was cooled to -78C. Then an excess of 13 (20 mL) was added and the vessel sealed.

The reaction was warmed to room temperature and stirred for 48 hours. After removal

of excess 1,3-butadiene (13) a white oily solid was collected and recrystallized from

diethyl ether to give 4.82 g of the title compound (74%). The material gave identical

spectral data to that previously reported in the literature.37 1H NMR (CDCI3, 300 MHz): 5

= 7.75-7.72 (d, 2H), 7.33-7.30 (d, 2H), 7.01 (m, 1H), 5.66-5.63 (m, 2H), 2.93-290 (m,

2H), 2.82-2.79 (m, 2H), 2.42 (s, 3H).

1-Tosyl-4,5-dipropyl-1,4-cyclohexadiene (17b). The title compound was

prepared following a modified literature method.101 In a thick walled flask with Teflon cap

dry toluene (10 mL) and compound 16 (1.31 g, 7.3 mmol) with 12 (1.01 g, 7.3 mmol)

under an argon atmosphere was heated at 130C for 48 hours. The reaction was cooled

to room temperature and the solvent removed under reduced pressure. The crude

material was purified by column chromatography eluting with CHCI3 to give a 1.58 g of a

yellow oil (68%). 1H NMR (CDCI3, 300 MHz): 5 = 7.76 (d, 2H), 7.33 (d, 2H), 6.96 (m,

1H), 2.86 (m, 2H), 2.74 (m, 2H), 2.42 (s, 3H), 1.96 (m, 4H), 1.32 (m, 2H), 1.30 (m, 2H),

0.87 (t, 3H), 0.86 (t, 3H); 13C NMR (CDCI3, 75 MHz): 5= 144.3, 137.9, 136.4, 135.3,

129.9, 128.3, 127.0, 126.4, 34.7, 34.3, 32.0, 28.2, 21.8, 21.4, 14.3; DART-MS [M+H]

319.1737, calcd 319.1726.

2-Ethoxycarbonyl-4,7-dihydro-2H-isoindole (18a). The title compound was

prepared following a modified literature method.37 A solution of 17a (2.5 g 10.7 mmol)

in dry THF (25 mL) was added dropwise at 0C to one equivalent of tBuOK (1.44 g ,









12.8 mmol) and ethyl isocyanoacetate (1.31 g, 11.6 mmol). The reaction was stirred at

room temperature for 4 hours. The solvent was removed and the crude material

redissolved in DCM (140 mL). The organic layer was washed with water (2 x 80 mL),

and brine (1 x 80 mL) and then dried over Na2SO4. The solvent removed and the crude

material recrystallized from hexanes yielding 1.64 g of light yellow crystals (80%). The

material gave identical spectral data to that previously reported in the literature.37 1H

NMR (CDCI3, 300 MHz): 5 = 8.97 (broad s, 1H), 6.72 (m, 1H), 5.94-5.82 (m, 2H), 4.31

(q, 2H), 3.46-3.43 (m, 2H), 3.24-3.21 (m, 2H), 1.35 (t, 3H).

2-Ethoxycarbonyl-4,7-dihydro-5,6-dipropyl-2H-isoindole (18b). The title

compound was prepared according to the procedure for 18a. A solution of tBuOK (930

mg, 8.3 mmol) in dry THF (30 mL) was cooled to 0C followed by the addition of ethyl

isocyanoacetate (0.9 mL, 8.2 mmol). The solution was stirred for 10 minutes then a

solution of 17b (2.4 g, 7.5 mmol) in dry THF (30 mL) was added dropwise. The reaction

was warmed to room temperature and stirred for 4 hours. The solvent removed and the

crude redissolved in DCM (120 mL). The organic layer was washed with water (2 x 80

mL) and brine (1 x 80 mL) then dried over Na2SO4. The solvent was removed producing

an oil that was purified by column chromatography eluting with CHCI3. The combined

fractions were recrystallized from EtOH to give 1.09 g of the title compound (52%). 1H

NMR (CDCI3, 300 MHz): 5 = 8.89 (br s, 1H), 6.69 (d, 1 H), 4.33 (q, 2H), 3.40 (m, 2H),

3.16 (m, 2H), 2.15 (q, 4H), 1.48 (m, 2H), 1.47 (m, 2H), 1.36 (t, 3H), 0.95 (t, 3H), 0.94 (t,

3H); 13C NMR (CDCI3, 75 MHz): 5= 161.7, 128.4, 127.7, 126.6, 120.5, 117.9, 117.2,

60.0, 35.7, 28.5, 26.9, 22.0, 14.8, 14.5; DART-MS 276.1968, calcd 276.1958.









2-Chloro-1,2,3,4-tetrahydro-3-(phenylsulfonyl)-naphthalene (20). The title

compound was prepared following a modified literature method.36 A solution of PhSCI

(18.6 mmol) in dry DCM (40 mL) was added dropwise to 19 (2.0 g, 11.5 mmol) in DCM

(30 mL) at 0C. After the addition, the reaction was stirred at room temperature for two

hours. The mixture was stored in a freezer over night and the precipitated removed by

filtration. The filtrate was cooled to 0C and diluted with DCM (50 mL). In one portion

77% m-CPBA (9.2 g, 41 mmol) was added and then stirred at room temperature for one

hour. A chilled 10% aqueous Na2SO3 (80 mL) was added and the mixture stirred at

room temperature for one hour. The organic layer was washed with 10% aqueous

Na2CO3 (30 mL), 10% aqueous Na2SO3 (80 mL), and 10% aqueous Na2CO3 (80 mL).

The organic layer collected and dried over K2C03 and the solvent removed. The crude

product recrystallized from EtOH to give 3.08 g of the title compound (87%). The

material gave identical spectral data to that previously reported in the literature.36 1H

NMR (CDCI3, 300 MHz): 5 = 7.96-7.57 (m, 5H), 7.22-7.19 (m, 2H), 7.14-7.09 (m, 2H),

4.84 (m, 1H), 3.75-3.70 (m, 1H), 3.51-3.44 (dd, 1H), 3.51-3.27 (dd, 1H), 3.20-3.11 (dd,

1 H), 3.07-3.06 (dd, 1 H).

4,9-Dihydro-2H-benzo[f]isoindole-1-carboxylic acid ethyl ester (21). The title

compound was prepared following a modified literature method.36 Compound 20 (3.06

g, 10 mmol) in dry THF (10 mL) was added dropwise to a solution of tBuOK (3.1 g, 27.6

mmol) with ethyl isocyanoacetate (1.13 g, 10 mmol) in dry THF (40 mL) at 0C. The

reaction was warmed to room temperature and then refluxed for one hour under an

argon atmosphere. The solvent was removed and the crude material dissolved in DCM

(120 mL). The organic layer was washed with water (2 x 100 mL) and brine (1 x 100









mL) collected and dried over K2C03. The crude material was recrystallized from EtOH

and hexanes to yield 1.53 g (65%). The material gave identical spectral data to that

previously reported in the literature.36 1H NMR (CDCI3, 300 MHz): 5 = 9.04 (broad s,

1H), 7.33 (m, 1H), 7.24-7.17 (m, 2H), 6.81 (d, 1H), 4.37 (q, 2H), 4.17 (s, 2H), 3.89 (s,

2H), 1.40 (t, 3H).

4a,5,8,8a-tetrahydronaphthoquione-1,4-dione (23). The title compound was

prepared following a modified literature method.102 Compound 22 (6.0 g, 55.5 mmol) in

AcOH (70 mL) was stirred at room temperature with 13 (12 g, 221.8 mmol) for 24 hours.

The mixture was poured into ice water (200 mL) and rapidly stirred. The precipitate was

collected and redissolved in warm ether and filtered to remove insoluble material. The

solvent was removed to give 3.75 g of the title compound (42%). The material gave

identical spectral data to that previously reported in the literature.87 1H NMR (CDCI3, 300

MHz): 5 = 6.67 (s, 2H), 5.70 (m, 2H), 3.27-3.23 (m, 2H), 2.52-2.16 (m, 4H).

5,8-Dimethoxy-1,4-dihyronaphthalene (24). The title compound was prepared

following a modified literature method.102 In acetone (85 mL) 23 (5.4 g, 33.3 mmol) with

an excess of K2C03 (17.0 g) and dimethyl sulfate (20.0 g, 158.5 mmol) under N2

atmosphere was refluxed for 40 hours. The mixture cooled to room temperature

followed by the addition of water (25 mL). The mixture was concentrated and then

poured into ice cold water (500 mL) with vigorous stirring. The formed precipitate was

collected and washed thoroughly with water to remove any residual K2C03. The crude

product was recrystallized from MeOH to give 6.05 g of the title compound (96%). The

material gave identical spectral data to that previously reported in the literature.87 1H

NMR (CDCI3, 300 MHz): 5 = 6.65 (s, 2H), 5.89 (s, 2H), 6.70 (s, 6H), 3.28 (s, 4H).









2-Chloro-1,2,3,4-tetrahydro-5,8-dimethoxy-3-(phenylsulfonyl)-naphthalene

(25). The title compound was prepared following a modified literature method.36 In dry

DCM (50 mL) cooled to 0C with 24 (3.5 g, 18.4 mmol) was treated dropwise with

PhSCI (23.0 mmol) in DCM (40 mL). After the addition the reaction was stirred at room

temperature for 2 hours. The mixture was stored in a freezer overnight and the formed

precipitate removed by filtration. The solution was diluted with DCM (50 mL) and cooled

to 0C followed by the addition of 77% m-CPBA (7.95 g, 46.0 mmol) in one portion. The

reaction was warmed to room temperature and stirred for one hour. A solution of chilled

10% aqueous Na2SO3 (100 mL) was added and the mixture stirred for one hour at room

temperature. The organic layer was washed with 10% aqueous Na2CO3 (35 mL), 10%

aqueous Na2SO3 (100 mL), and 10% aqueous Na2CO3 (100 mL). The organic layer was

dried over K2C03 and the solvent removed. The crude product was recrystallized from

an EtOH and hexane mixture to give 4.30 g of the title compound (64%). The material

gave identical spectral data to that previously reported in the literature.36 1H NMR

(CDCl3, 300 MHz): 5 = 7.94-7.90 (m, 2H), 7.67-7.54 (m, 3H), 6.66 (s, 2H), 4.85-4.80 (m,

1H), 3.77-3.67 (overlapping s+s+m, 3H+3H+1H), 3.40-3.33 (dd, 1H), 3.24-3.16 (m, 3H).

5,8-Dimethoxy-4,9-dihydro-2H-benzo[f]isoindole-1-carboxylic acid ethyl

ester (26). The title compound was prepared following a modified literature method.36

A solution of tBuOK (1.83 g, 16.3 mmol) in dry THF (60 mL) was cooled to 0C followed

by the addition of ethyl isocyanoacetate (2.21 g, 19.6 mmol). To this solution, 25 (3.0 g,

8.1 mmol) in THF (30 mL) was added dropwise. The reaction was warmed to room

temperature and then refluxed for one hour. The solvent was removed and the material

dissolved in DCM (120 mL).The organic layer was washed with water (2 x 100 mL) and









brine (1 x 100 mL) then dried over K2C03. The solvent was removed yielding a red oil

that precipitated yellow crystals upon the addition of EtOH. The precipitate was filtered

and washed with hexanes to give 1.73 g of the title compound (70%). The material gave

identical spectral data to that previously reported in the literature.36 1H NMR (CDCI3, 300

MHz): 5 = 9.03 (br s, 1 H), 6.82 (d, 1H), 6.71 (s, 2H), 4.39 (q, 2H), 4.08 (m, 2H), 4.06-

3.82 (overlapping s+d, 6H+2H), 1.41 (t, 3H).

1,4,4a,9a-Tetrahydro-1,4-ethanoanthracene-9,10-dione (28). The title

compound was prepared following a modified literature method.103 A mixture of 1,3-

cyclohexadiene (7.0 g, 87.3 mmol) and 27 (13.8 g, 87.3 mmol) in EtOH (90 mL) was

refluxed for 3 hours. The reaction was cooled overnight in a freezer. The precipitated

crystals were collected and then recrystallized from boiling EtOH to give 14.05 g of the

title compound (67%). The material gave identical spectral data to that previously

reported in the literature.103 1H NMR (CDCI3, 300 MHz): 5 = 7.99-7.96 (m, 2H), 7.67-

7.63 (m, 2H), 6.11 (dd, 2H), 3.32-3.30 (m, 2H), 3.18-3.17 (m, 2H), 1.77-1.73 (m, 2H),

1.39-1.34 (m, 2H).

1,2,3,4,4a,9,9a,10-Octahydro-1,4-ethanoanthracene-9,10-diol (29). The title

compound was prepared following a modified literature method.89 A solution of 28 (5.7

g, 23.9 mmol) in anhydrous MeOH (150 mL) was cooled to 0C under N2 atmosphere.

In one portion NaBH4 (2.5 g, 66.0 mmol) was added and the reaction stirred at 0C for

two hours. The solvent was removed and the crude material purified by column

chromatography eluting with a hexane:THF (5:2) solvent mixture removing the first light

yellow band. The solvent polarity was then increased to pure THF. The combined

fractions afforded 5.15 g of the title compound (89%). The material gave identical









spectral data to that previously reported in the literature.89 1H NMR (CDC3, 300 MHz): 5

= 7.30 (s, 4H), 6.35 (broad s, 2H), 4.70-4.67 (m, 2H), 3.03-3.01 (m, 2H), 2.76 (broad s,

2H), 2.21 (broad s, 2H), 1.60-1.57 (m, 2H), 1.37-1.34 (m, 2H).

1,4-Dihydro-1,4-ethanoanthracene (30). The title compound was prepared

following a modified literature method.91 A mixture of TsCI (12.15 g, 63.7 mmol) and 29

(5.15 g, 21.3 mmol) in dry pyridine (40 mL) under N2 atmosphere was stirred for 48

hours at room temperature. The reaction was poured over ice (300 g) and stirred. The

precipitated material was collected and dried over MgSO4. The crude product was

purified by column chromatography eluting with hexanes yielding 3.25 g of the title

compound (74%). The material gave identical spectral data to that previously reported

in the literature.90 1H NMR (CDCI3, 300 MHz): 5 = 7.80-7.77 (AA'BB', 2H), 7.59 (s, 2H),

7.43-7.39 (AA'BB', 2H), 6.60-6.57 (m, 2H), 4.06 (m, 2.12), 1.69-1.56 (m, 4H).

2-Chloro-1,2,3,4-tetrahydro-3-phenylsulfonyl-1,4-ethanoanthracene (31).

The title compound was prepared following a modified literature method.66 A solution of

30 (3.25 g, 15.8 mmol) in dry DCM (150 mL) was cooled to 0C in an ice bath. The

solution was then treated dropwise with PhSCI (18.9 mmol) in dry DCM (60 mL). The

reaction was stirred at room temperature for one hour. The organic layer was washed

with 10% aqueous NaHCO3(80 mL), water (80 mL), and brine (80 mL). The organic

layer was collected and dried over Na2SO4.The solvent removed yielding a yellow oil

that was diluted with hexanes and EtOH precipitating 4.3 g of white powder that was

collected and dried. The crude material was dissolved in DCM (100 mL) and cooled to

0C followed by the addition of 77% m-CPBA (6.8 g, 39.4 mmol) in one portion. The

reaction was warmed to room temperature and stirred overnight. The precipitate was









filtered off and the solvent removed. The material was recrystallized from hexanes/EtOH

to give 3.53 g of the title compound (59%). The material gave identical spectral data to

that previously reported in the literature.66 1H NMR (CDCI3, 300 MHz): 6 = 7.81-7.78 (m,

4H), 7.68 (s, 1H), 7.62-7.56 (m, 2H), 7.51-7.43 (m, 4H), 4.35-4.32 (m, 1H), 3.85-3.83

(m, 1H), 3.63-3.60 (m, 1H), 3.41-3.38 (m, 1H), 2.43-2.33 (m, 1H), 2.08-1.98 (m, 1H),

1.67-1.43 (m, 2H).

4,11-Dihydro-4,11 -ethano-2H-napth[2,3f]isoindole-1 -carboxylic acid ethyl

ester (32). The title compound was prepared following a modified literature method.66 A

solution of dry THF (40 mL) and 31 (2.63 g, 6.9 mmol) was added dropwise at 0C to

tBuOK (1.85 g, 16.5 mmol) and ethyl isocyanoacetate (93 mg, 8.2 mmol). After the

addition the reaction was warmed to room temperature and stirred overnight. The

organic layer was washed with water (2 x 100 mL) and brine (1 x 100 mL) collected and

dried over Na2SO4. The solvent was removed yielding an oil. The addition of hexane

and EtOH precipitated the title compound as a white powder to give 805 mg (37%). The

material gave identical spectral data to that previously reported in the literature.66 1H

NMR (CDCI3, 300 MHz): 5 = 8.45 (broad s, 1H), 7.74 (m, 2H), 7.68 (s, 1H), 7.61 (s, 1H),

7.38 (m, 2H), 6.07 (s, 1H), 4.90 (s, 1H), 4.39-4.34 (m, 3H), 1.81 (m, 4H), 1.44-1.40 (m,

3H).

1,4-Epoxy-1,4-dihydronaphthalene (33). The title compound was prepared

following a modified literature method.92 In dry THF (120 mL) anthranilic acid (9.5 g,

69.3 mmol) was cooled to 0C followed by the addition of isoamyl nitrite (20 mL)

dropwise. The mixture was then warmed to room temperature and stirred for one hour.

The yellow precipitate was collected by filtration (Caution: explosion hazard do not allow









precipitate to dry or come in contact with metal) and transferred to a flask with dry THF

(120 mL), furan (4.40 g, 64.6 mmol), and propylene oxide (6 mL). The mixture was

slowly warmed to 70C under a N2 atmosphere until the precipitate disappeared with

adequate venting. The solution was then heated to reflux for 20 minutes. The solvent

was removed under reduced pressure and the crude product purified by column

chromatography eluting with 10% ethyl acetate in hexanes. The material from the

combined fractions was recrystallized from hexanes to give 4.60 g of the title compound

(49%). The material gave identical spectral data to that previously reported in the

literature.93 1H NMR (CDCI3, 300 MHz): 5 = 7.23 (dd, 2H), 7.01 (s, 2H), 6.95 (dd, 2H),

5.70 (s, 2H).

9,10-Epoxy-1,4,4a,9,9a,10-hexahydroanthracene (34). The title compound

was prepared following a modified literature method.38 A 60 mL thick walled flask with

Teflon screw cap with 33 (5.05 g, 35.0 mmol) and NaHCO3 (2.5 g, 29.75 mmol)

dissolved in pyridine (20 mL) freshly distilled over NaOH. To this solution 3-sulfolene

(4.55 g, 38.5 mmol) was added in seven equal portions. The reaction was heated at

120C for 10 hours after each addition of 3-sulfolene. The reaction was carefully vented

prior to each new addition and heating cycle. The mixture was filtered through celite and

the solvent removed. The crude material was dissolved in DCM and passed through a

short (4") column of silica-gel. The solvent was removed to give yellow oil that

precipitated crystals upon addition of MeOH. The product was collected and dried to

give 4.89 g of the title compound (70%). The material gave identical spectral data to that

previously reported in the literature.38 1H NMR (CDC3, 300 MHz): 5 = 7.23 (AA'BB', 2H),









7.13 (AA'BB', 2H), 5.95 (m, 2H), 5.00 (s, 2H), 2.52-2.46 (m, 2H), 2.09-2.01 (m, 2H),

1.95-1.89 (m, 2H).

1,4-Dihydroanthracene (35). The title compound was prepared following a

modified literature method.38 Compound 34 (4.89 g, 24.7 mmol) dissolved in a mixture

of EtOH (100 mL) and HCI (10 mL) heated to reflux for 24 hours under an argon

atmosphere. After cooling in an ice bath a crystalline precipitate formed and was

collected. The material was recrystallized from MeOH and dried to give 3.64 g of the

title compound (82%). The material gave identical spectral data to that previously

reported in the literature.381H NMR (CDCI3, 300 MHz): = 7.77 (AA'BB', 2H), 7.64 (s,

2H), 7.42 (AA'BB', 2H), 6.06 (m, 2H), 3.60 (s, 4H).

2-Chloro-3-(phenylsulfonyl)-1,2,3,4-tetrahydroanthracene (36). The title

compound was prepared following a modified literature method.38 In dry DCM (80 mL)

35 (2.5 g, 13.9 mmol) was cooled to -78C and treated dropwise with a solution of

PhSCI (16.5 mmol) in dry DCM (80 mL). After the addition the reaction mixture was

stirred for 4 hours at room temperature and then placed in a freezer for 2 hours. The

precipitated was removed. The reaction mixture was then cooled to 0C followed by the

addition of 77% m-CPBA (7.18 g, 41.6 mmol). The reaction was warmed to room

temperature and stirred under a N2 atmosphere for 48 hours. The reaction was diluted

with aqueous 10% Na2SO3 (50 mL) and stirred for 30 minutes. The organic layer was

washed with aqueous 10% Na2CO3 (80 mL), aqueous10% Na2SO3 (80 mL), and

aqueous 10% Na2CO3 (80 mL) then dried over K2C03. The solvent was removed under

reduced pressure and the crude material recrystallized from MeOH yielding 3.55 g of

the title compound (72%). The material gave identical spectral data to that previously









reported in the literature.381H NMR (CDCI3, 300 MHz): = 7.99 (m, 2H), 7.77 (m, 2H),

7.70 (m, 1H), 7.64 (s, 1H), 7.61 (m, 2H), 7.46 (m, 2H), 4.97 (m, 1H), 3.79 (m, 1H), 3.58

(dd, 1 H), 3.45 (dd, 1 H), 3.34 (dd, 1 H), 3.28 (dd, 1H).

2-(Phenylsulfonyl)-1,2-dihydroanthracene (37). The title compound was

prepared following a modified literature method.38 In dry DCM (30 mL) compound 36

(3.54 g, 9.91 mmol) was treated dropwise with one equivalent of DBU (1.51 g, 9.91

mmol). After the addition the reaction mixture was stirred at room temperature for one

hour then diluted with water (30 mL). The layers were separated and the aqueous layer

was washed with DCM (3 x 50 mL). The organic layers combined and dried over

Na2SO4 and the solvent removed under reduced pressure. The crude material was

recrystallized from MeOH yielding 2.80 g of the title compound (89%). The material

gave identical spectral data to that previously reported in the literature.38 1H NMR

(CDCI3, 300 MHz): 5 = 7.75 (m, 2H), 7.66 (m, 2H), 7.43-7.37 (m, 3H), 7.34 (m, 1H),

7.29-7.20 (m, overlap with solvent, 3H), 6.80 (d, 1H), 6.13 (dd, 1H), 4.13 (m, 1H), 3.61

(dd, 1 H), 3.40 (dd, 1 H).

Ethyl-4,11-dihydro-2H-naphtho[2,3-f]isoindole-1-carboxylate (38). The title

compound was prepared following a modified literature method.38 In dry THF (30 mL)

tBuOK (1.4 g, 12.5 mmol) was stirred at 0C followed by the addition of ethyl

isocyanoacetate (988 mg, 8.73 mmol) and stirred at room temperature. Compound 37

(2.80 g, 8.73 mmol) in dry THF (30 mL) was added dropwise at 0C. The mixture was

warmed to room temperature and stirred overnight. The solvent was removed and the

crude material redissolved in DCM (120 mL). The organic layer was washed with water

(2 x 100 mL) and brine (1 x 100 mL) and dried over K2C03. The solvent removed under









reduced pressure and the crude material purified by column chromatography eluting

with DCM/Hexanes (80:20). The combined fractions recrystallized from MeOH yielding

1.163 g of the title compound (46%). The material gave identical spectral data to that

previously reported in the literature.38 1H NMR (CDCI3, 300 MHz) 5 = 8.96 (br s, 1 H),

7.80 (s overlapped, 1H), 7.76 (m, 2H), 7.74 (s overlapped, 1H), 7.44 (m, 2H), 6.86 (d,

1H), 4.43 (q overlapped, 2H), 4.39 (s, 2H), 4.06 (s, 2H), 1.44 (t, 3H).

4,7-dihydro-2H-isoindole (BP). A suspension of 18a (600 mg, 3.1 mmol) in

ethylene glycol (20 mL) with KOH (880 mg, 15.7 mmol) was thoroughly purged with

argon. The mixture was heated to 170C for 1 hour. The reaction was immediately

cooled in an ice bath and diluted with DCM (100 mL). The organic layer was washed

with water (2 x50 mL) and brine (1 x 50 mL) collected and dried over Na2SO4. The

solvent was removed producing a dark amber colored oil that was vacuum dried to a

consistent weight to give 287 mg of the title compound (77%). TLC analysis verified that

no starting material was present. The title compound was immediately used in a

porphyrin synthesis without further purification due its instability. ESI-TOF [M+H]+ and

[2M+H]+ 120.0813, 239.1545, calcd 120.0808, 239.1543.

4,9-Dihydro-2H-benzo[f]isoindole (NP). The title compound was prepared

from 21 following the procedure used for BP (86 %). APCI-MS [M+H]+ 170.0961, calcd

170.0964.

5,8-Dimethoxy-4,9-dihydro-2H-benzo[f]isoindole (NP2). The title compound

was prepared from 26 following the procedure used for BP (61%). ESI-TOF [M+H]+ and

[M+Na]+ 230.1176, 252.0990, calcd 230.1176, 252.0990.









4,11-Dihydro-4,1 1-ethano-2H-napth[2,3f]isoindole (AP). The title compound

was prepared from 32 following the procedure used for BP (87%). ESI-TOF m/z

246.1275, calcd 246.1277.

4,11-Dihydro-2H-naphtho[2,3-f]isoindole (AP2). The title compound was

prepared from 38 following the procedure used for BP (82%). CI-MS [M]' and [M+H]+

219.1054, 220.1132 calcd 219.1048, 220.1126.

Tetraphenyltetrabenzoporphyrin (39a). The title compound was prepared

following a modified literature method.37 A solution of BP (287 mg, 2.4 mmol) and 1

(255 mg, 2.4 mmol) in dry DCM (250 mL) was stirred under an argon atmosphere

protected from light. After the addition BF3.O(Et)2 (60 mg, 0.4 mmol) the reaction was

stirred for 3 hours at room temperature. In one portion DDQ (603 mg, 2.7 mmol) was

added and the reaction stirred for one hour. The solvent was removed and the material

redissolved in toluene (80 mL) with DDQ (655 mg, 2.9 mmol) heated to reflux under

argon for one hour. The solvent was removed and the crude material dissolved in DCM

(120 mL). The organic layer was washed with aqueous 10% Na2SO3 (2 x 100 mL),

water (2 x 100 mL) and brine (1 x 100 mL) collected and dried over Na2SO4. The crude

material was loaded on silica and purified by column chromatography eluting with 2%

MeOH in DCM. The first bright green band was collected and the solvent removed. The

material was dissolved in a minimal amount of boiling CHCI3 vigorously stirred and

diluted with MeOH (10x volume) precipitating small green crystalline flakes. The

precipitate was collected and repeatedly washed with MeOH yielding 140 mg of the title

compound (29%). The NMR spectra were recorded on a Varian Inova 500 MHz,

operating at 500 MHz for 1H, 125 MHz for 13C, and 50 MHz for 15N. The probe was an









indirect detection triple resonance probe, with z-axis gradients. The proton spectrum at

25C displayed a broad signal for the protons of the orthophenylene moiety, due to the

exchange of the NH protons.104 This broad signal was resolved at -50C into two AA'BB'

patterns, while the NH protons displayed a sharp signal at -1.34 ppm, as the exchange

became slower. Because of the limited solubility of H2TPTBP in the NMR solvent, 13C

chemical shifts were measured by indirect detection, in a gHMBC spectrum. The

material gave identical spectral data to that previously reported in the literature.104 1H

NMR (CDCI3, 500 MHz): 5 = 8.40 (m, 8H), 7.96 (m, 4H), 7.88 (m, 8H), 7.43 (AA'BB',

4H), 7.34 (AA'BB', 4H), 7.18 (AA'BB', 4H), 6.98 (AA'BB', 4H), -1.34 (s, 2H); 13C NMR

(CDCI3, 125 MHz) 5= 115.9, 124.2, 124.9, 126.1, 126.7, 129.5, 131.6, 133.7, 134.7,

140.1, 141.9; ESI-TOF [M+H]+ 815.3169, calcd 815.3169.

Tetra(3,5-di-tert-butylphenyl)tetrabenzoporphyrin (39b). The title compound

(H2Ar4TBP) was prepared from a solution of BP (296 mg, 2.5 mmol) and 3 (542 mg, 2.5

mmol) in dry DCM (250 mL) according to the procedure for 39a. The crude product was

purified by column chromatography eluting with DCM collecting the second large green

band. The solvent was removed and the material dissolved in boiling methanol after

cooling 158 mg of the title compound was collected by filtration (20%). 1H NMR

(pyridine-ds, 500 MHz): 5 = 8.48 (s, 8H), 8.25 (s, 4H), 7.66 (d, 8H), 7.47 (m, 8H), 1.59

(s, 72H); 13C NMR (pyridine-ds, 125 MHz) 5 = 152.6, 138.4, 130.2, 126.4, 125.5, 122.7,

118.0, 35.7, 32.0; MALDI-MS [M]+ and [M+H]+ 1262.8042, 1263.8179, calcd

1262.8099, 1263.8177.

Tetra(4-(9,9-dihexyl-fluorenyl)-phenyl)tetrabenzoporphyrin (39c). The title

compound (H2ArF4TBP) was prepared from a solution of BP (143 mg, 1.2 mmol) and 9









(520 mg, 1.2 mmol) in dry DCM (150 mL) according to the procedure for 39a. The crude

product was purified by column chromatography eluting with 20% EtOAc in hexane

collecting the first large green band. The solvent was removed and the material

precipitated from DCM and MeOH to give 110 mg of the title compound (17%).1H NMR

(pyridine-ds, 500 MHz): 5 = 8.67 (d, 8H), 8.50 (d, 8H), 8.24 (d, 4H), 8.19(d, 4H), 8.05 (d,

4H), 7.85 (d, 8H), 7.70 (d, 4H), 7.55 (m, 8H), 7.42 (m, 8H), 2.44 (dd, 8H), 2.35 (dd, 8H),

1.28 (m, 16H), 1.23 (m, 32H), 1.13 (m, 16H), 0.88 (t, 24H); 13C NMR (pyridine-ds, 125

MHz) 5 = 153.0, 152.3, 143.2, 142.2, 141.9, 141.8, 140.5, 138.0, 136.2, 128.4,128.2,

128.0, 127.5, 127.0, 125.4, 124.1, 122.8, 121.2, 120.9, 116.8, 56.5, 41.1, 32.1, 30.4,

24.9, 23.1, 14.4; MALDI-MS [M]' and [M+H]+ 2143.3074, 2144.3104, calcd 2143.3107,

2144.3185.

Tetraphenyltetranaphthoporphyrin (40a). The title compound was prepared

following a modified literature method.36 In dry DCM (250 mL), NP (430 mg, 2.54 mmol)

and 1 (270 mg, 2.54 mmol) was stirred under argon atmosphere and protected from

light. After the addition of BF3.O(Et)2 (72 mg, 0.5 mmol) the reaction was stirred at room

temperature for 90 minutes. In one portion DDQ (2.88 g, 12.7 mmol) was added and the

reaction brought to reflux for one hour. The organic layer was washed with 10%

aqueous Na2SO3 (2 x 100 mL), and water (2 x 100 mL) and dried over K2C03. The

solvent removed and the crude material loaded on neutral silica eluting with DCM

collecting the first major green band. The material was redissolved in boiling CHCI3 and

diluted with excess MeOH precipitating fine green crystals to give 116 mg of the title

compound (20%). The material gave identical spectral data to that previously reported









in the literature.361H NMR (CDCI3-TFA, 300 MHz): 5 = 8.63-8.60 (m, 8H), 8.08-7.97 (m,

20H), 7.75-7.72 (m, 8H), 7.53-7.50 (m, 8H), 2.49 (s, 4H).

1,4,10,13,19,22,28,31 -Octamethoxy-7,16,25,34-tetrakis(3,5-di-

tertbutylphenyl)-tetranaphthoporphyrin (40b). The title compound

(H2Ar4TNP(OMe)8) (40b) was prepared according to the procedure for 40a from a

solution of NP2 (242 mg, 1.0 mmol) and 3 (230 mg, 1.0 mmol) in dry DCM (180 mL).

The solvent was removed and the crude material purified by chromatography eluting

with DCM followed by multiple precipitations from DCM and MeOH to give 72 mg of the

title compound (16%). 1H NMR (pyridine-ds, 500 MHz): 5 = 8.66 (s, 8H), 8.49 (s, 8H),

8.37 (s, 4H), 6.86 (d, 8H), 4.03 (s, 24H), 1.60 (s, 72H); 13C NMR (pyridine-ds, 125 MHz)

S= 152.9, 151.1, 142.8, 136.1, 128.5, 125.3, 122.6, 120.2, 119.5, 116.8, 103.5, 55.7,

35.4, 31.8; MALDI-TOF MS [M]' 1703.9685, calcd 1703.9603.

8,19,30,41-tetrakis(3,5-di-butylphenyl)-6,10,17,22,27,32,39,43-octahydro-

6,43:10,17:21,28:32,39-tetraethano-45H,47H-tetraanthraporphyrin (41). The title

compound was prepared following a modified literature method.66 A mixture of 3 (200

mg, 0.9 mmol) with AP (225 mg, 0.9 mmol) in dry DCM (170 mL) was stirred protected

from light under an argon atmosphere. After the addition of BF3.O(Et)2 (58 mg, 0.4

mmol) the reaction was stirred at room temperature for 18 hours. In one portion DDQ

(1.08 g, 4.75 mmol) was added and the mixture stirred for 90 minutes. The organic layer

was washed with 10% aqueous Na2SO3 (2 x 100 mL), water (1 x 100 mL), and brine (1

x 100 mL) collected and dried over Na2SO4. The solvent removed and the crude

material passed through a silica column eluting with DCM. The combined fractions

dissolved in warm THF (25 mL) and diluted with MeOH (250 mL). The solution became









turbid and was placed in the refrigerator overnight. The formed precipitate was filtered

and washed repeatedly with MeOH. The precipitate was collected and dried to give 209

mg of the title compound (51%). The material gave identical spectral data to that

previously reported in the literature.66 1H NMR (CDC3, 300 MHz): 5 = 8.41-7.26 (mixture

of isomers, overlap with solvent, 36H), 3.95 (m, 8H), 1.83-1.63 (m, bridge + t-Bu, 88H).

Tetra(3,5-di-tert-butylphenyl)tetraanthroporphyrin (42). The title compound

was prepared following a modified literature method.38 The solvents used in this

procedure were thoroughly purged with argon or subjected to freeze pump thaw cycles

due to the oxygen sensitivity of 42. A mixture of AP2 (150 mg, 0.67 mmol) and 3 (149

mg, 0.68 mmol) in dry DCM (100 mL) was stirred under an argon atmosphere protected

from light. The reaction was stirred for one hour after the addition of BF3-OEt2 (20 pL). A

solution of DDQ (232 mg, 1.0 mmol) in toluene (4 mL) was subjected to freeze pump

thaw cycles in a schlenk flask prior to addition. After the addition the reaction was stirred

for one hour at room temperature and then quenched by the addition of aqueous 10%

Na2SO3 (100 mL). The organic layer was separated and washed with aqueous 10%

Na2SO3 (100 mL), aqueous 10% Na2CO3 (100 mL), and brine (100 mL). The organic

layer was dried over Na2SO4 and the solvent removed under reduced pressure. The

material was purified by column chromatography eluting with DCM. The combined

fractions were concentrated and the material precipitated by the addition of excess

MeOH. The precipitate was collected to give 95 mg of the title compound (33%). 1H

NMR (pyridine-ds, 500 MHz): 5 = 8.67 (s, 8H), 8.65 (s, 8H), 8.58 (s, 4H), 8.37 (s, 8H),

8.15 (s, 8H), 7.52 (t, 8H), 1.67 (s, 72H); 13C NMR (pyridine-ds, 125 MHz) 5 = 32.2, 35.9,









116.3, 123.2, 125.7, 126.1, 128.2, 129.1, 129.6, 130.8, 132.8, 136.7; MALDI-TOF MS

[M]+ 1663.9403, calcd 1663.9384.

Bis(3-ethoxycarbonyl-4,7-dihydro-2H-isoindolyl)methane (43a). The title

compound was prepared following a modified literature method.59 A solution of 18a

(1.606 g, 8.4 mmol) and dimethoxy methane (319 mg, 4.2 mmol) in AcOH (130 mL) and

TsOH (165 mg, 0.9 mmol) under N2 atmosphere was stirred for 24 hours. The reaction

was poured into ice water (200 mL) and vigorously stirred. The precipitated material

was collected and washed with water (lx 100 mL) and cold MeOH (2 x 50 mL). The title

compound was dried under vacuum to give 1.38 g (85%). The material gave identical

spectral data to that previously reported in the literature.59 1H NMR (CDCI3-d6-DMSO,

300 MHz): 5 = 11.19 (brs, 2H), 5.77 (m, 4H), 4.17 (q, 4H), 3.71 (s, 2H), 3.24 (m, 4H

overlap with solvent), 3.02 (m, 4H), 1.27 (t, 6H).

Bis(3-ethoxycarbonyl-4,7-dihydro-5,6-dipropyl-2H-isoindolyl)methane (43b).

The title compound was prepared from a solution of 18b (920 mg, 3.3 mmol), dimethoxy

methane (127 mg, 1.7 mmol), TsOH (75 mg, 0.4 mmol) in 75 mL of AcOH following the

procedure for 43a. The crude material was reprecipitated from boiling CHCI3 and

excess MeOH to give 470 mg of the title compound (50%). 1H NMR (CDCI3, 300 MHz):

6 = 9.43 (s, 2H), 4.26 (q, 3H), 3.88 (s, 2H), 3.37 (m, 4H), 3.51 (m, 4H), 2.16 (m, 8H),

1.46 (m, 8H), 1.30 (t, 6H), 0.95 (t, 3H), 0.94 (t, 3H); 13C NMR (CDCl3, 75 MHz): 5=

162.2, 128.7, 128.4, 127.3, 117.5, 116.0, 60.0, 35.7, 28.9, 26.6, 23.3, 22.0, 14.7, 14.6;

ESI- MS [M+H]+ 563.3851, calcd 563.3843.

Bis(4,7-dihydro-2H-isoindolyl)methane (44a). The title compound was

prepared according to the procedure used for BP. A suspension of 43a (650 mg, 1.65









mmol) in ethylene glycol (40 mL) with KOH (925 mg, 16.5 mmol) was thoroughly purged

with argon and heated to 170C for 1 hour. The isolated material was dried under

vacuum to a consistent weight to give 351 mg of the title compound (84%). Due to

instability 44a was used immediately and not subjected to further purification. DART-MS

[M+H]+ 251.1563, calcd 251.1543.

Bis(4,7-dihydro-5,6-dipropyl-2H-isoindolyl)methane (44b). The title

compound was prepared according to the procedure used for 44a from 43b (450 mg,

0.8 mmol) to give 255 mg of the title compound (76%). ESI-MS [M+H]+ 419.3429, calcd

419.3421.

5,15-Diphenyltetrabenzoporphyrin (45a). The title compound was prepared

following a modified literature method.59 In dry DCM (200 mL) 44a (352 mg, 1.4 mmol)

and 1 (149 mg, 1.4 mmol) were stirred protected from light under an argon atmosphere.

After the addition of TFA (30 mg, 0.3 mmol) the reaction was stirred for 18 hours at

room temperature. DDQ (478 mg, 2.1 mmol) was added in one portion and the reaction

stirred for one hour. The solvent was removed under reduced pressure. The material

was redissolved in toluene (120 mL) with DDQ (634 mg, 2.8 mmol) and refluxed for 30

minutes. The solvent was removed and the crude material dissolved in DCM (120 mL).

The organic layer was washed with aqueous 10% Na2SO3 (2 x 100 mL), water (2 x 100

mL), and brine (1 x 100 mL). The organic layer was collected and dried over Na2SO4.

The material loaded on silica and purified by column chromatography eluting with DCM.

The combined fractions were dissolved in a minimal amount of boiling CHCI3 and

precipitated by the slow addition of MeOH (excess) under vigorous stirring. The

precipitate was collected and repeatedly washed with MeOH to give 178 mg of the title









compound (38%). The material gave identical spectral data to that previously reported

in the literature.59 1H NMR (CDCI3-TFA, 300 MHz): 5 = 10.98 (s, 2H), 9.38 (d, 4H), 8.44

(m, 4H), 8.17 (ddd, 4H), 8.12 (m, 2H), 8.04 (m, 4H), 7.83 (ddd, 4H), 7.58 (d, 4H), 3.51

(br s, 4H).

5,15-Di(3,5-di-tert-butylphenyl)tetrabenzoporphyrin (45b). The title

compound was prepared following a modified literature method.59 Following the

procedure for 45a the title compound was prepared from a solution of 44a (309 mg, 1.2

mmol) and 3 (269 mg, 1.2 mmol) in dry DCM (180 mL). The crude material was purified

by column chromatography eluting with DCM. Then precipitated by dissolving in a

minimum amount of boiling CHCI3 diluting with MeOH to give 158 mg of the title

compound after filtration and repeated washing with MeOH (29%). The material gave

identical spectral data to that previously reported in the literature.59 1H NMR (CD2CI2,

300 MHz): 5 = 11.15 (s, 2H), 9.73 (d, 4H), 8.17 (m, 4H), 8.12 (m + d overlapped, 6H),

7.77 (m, 4H), 7.53 (m, 4H), 1.56 (s, 36H), -1.25 (br s, 2H).

5,15-Di((3,5-di-tert-butylphenyl)-phenyl)tetrabenzoporphyrin (45c). The title

compound was prepared from a solution of 44a (369 mg, 1.5 mmol) and 6 (546 mg, 1.5

mmol) in dry DCM (180 mL) following the procedure used for 45a. The material was

purified by column chromatography on silica-gel eluting with DCM. The fractions were

concentrated and the title compound precipitated from the addition of excess MeOH to

give 220 mg (25%). 1H NMR (pyridine-ds, 500 MHz): 5 = 1.44 (s, 36H), 7.67 (d, 8H),

7.94 (t, 4H), 8.14 (d, 8H), 8.21 (t, 4H), 8.29 (d, 4H), 8.90 (s, 2H), 8.92 (s, 4H), 10.00 (d,

4H), 11.56 (s, 2H); 13C NMR (pyridine-ds, 125 MHz) 5 =31.8, 35.0, 94.3, 117.7, 122.4,









125.9, 126.8, 128.0, 128.3, 130.8, 138.0, 138.5, 140.3, 143.5, 150.5,151.9; DART-MS

[M+H]+ 1191.6296, calcd 1191.6299.

5,15-Di(3,5-di-tert-butylphenyl)octapropyltetrabenzoporphyrin (45d). The

title compound was from a solution of 44b (255 mg, 0.6 mmol) and 3 (133 mg, 0.6

mmol) in dry DCM (110 mL). The material was purified by column chromatography on

silica-gel eluting with 2% MeOH in DCM to give 68 mg of the title compound following

the procedure for 45a (18%). 1H NMR (pyridine-d5, 500 MHz): 5 = 11.66 (s, 2H), 9.90

(s, 4H), 8.45 (s, 4H), 8.42 (s, 2H), 7.75 (s, 4H), 3.26 (t, 8H), 3.08 (t, 8H), 2.07 (sex, 8H),

1.93 (sex, 8H), 1.72 (s, 36H), 1.25 (t, 12H), 1.24 (t, 12H); 13C NMR (pyridine-ds, 125

MHz) 5 = 152.8, 141.0, 140.7, 140.2, 138.6, 136.6, 128.0, 126.2, 123.2, 122.1, 117.9,

93.6, 36.6, 36.4, 35.8, 32.2, 25.5, 25.2, 14.8, 14.7; DART-MS [M+H]+ 1223.8763, calcd

1223.8803.

Platinum Tetraphenyltetrabenzoporphyrin (Pt-39a). A solution of 39a (49 mg,

60.1 pmol) and platinum acetate (83 mg, 60.1 pmol) in benzonitrile (25 mL) was

thoroughly purged with argon. The reaction was then submerged in a pre-heated oil

bath at 200 C and refluxed until the Q-band of 39a disappeared from the UV-Vis

spectrum. The solvent was removed under reduced pressure and the crude material

dissolved in DCM and filtered through a plug of Celite. The material was then loaded on

silica and purified via column chromatography eluting with 30% DCM in Hexanes

yielding 45 mg of the title compound (74%). 1H NMR (pyridine-ds, 500 MHz): 5 = 8.35

(d, 8H), 7.96 (t, 4H), 7.92 (t, 8H), 7.42 (m, 8H), 7.37 (m, 8H); 13C NMR (pyridine- ds, 125

MHz) 5 = 142.1, 138.2, 136.7, 134.2, 129.9, 129.9, 126.3, 124.8; ESI-TOF m/z

1006.2549, calcd 1006.2562.









Platinum Tetra(3,5-di-tert-butylphenyl)tetrabenzoporphyrin (Pt-39b). The

title compound was prepared from 39b (80 mg, 63.3 pmol) and platinum acetate (87

mg, 63.3 pmol) in benzonitrile (30 mL) using the procedure for Pt-39a. The crude

material was purified via column chromatography eluting with 30% DCM in hexanes

yielding 32 mg of the title compound (35%). 1H NMR (pyridine- d5, 500 MHz): 5 = 8.31

(s, 8H), 8.17 (s, 8H), 7.51 (m, 8H), 7.44 (m, 8H), 1.46 (s, 72H); 13C NMR (pyridine- ds,

125 MHz) 5 = 153.3, 138.9, 136.6, 129.0, 126.4, 125.6, 122.9, 120.5, 35.6, 32.0; DART-

MS [M+H]+ 1457.7687, calcd 1457.7694.

Platinum Tetra(4-(9,9-dihexyl-fluorenyl)-phenyl)tetrabenzoporphyrin (Pt-

39c). The title compound was prepared from 39c (76 mg, 35.4 pmol) and platinum

acetate (49 mg, 35.4 pmol) in benzonitrile (25 mL) using the procedure for Pt-39a. The

crude material was purified by chromatography eluting with 20% hexanes in DCM. The

fractions combined and concentrated in DCM then diluted with excess MeOH to give 78

mg of the title compound (94%). 1H NMR (pyridine- d5, 500 MHz): 5 = 8.50 (m, 12H),

8.21 (d, 4H), 8.18 (d, 4H), 8.04 (d, 4H), 7.69 (d, 8H), 7.66 (d, 4H), 7.53 (t, 8H), 7.30 (m,

8H), 2.37 (t, 4H), 2.27 (t, 4H), 1.14 (m, 16H), 1.11 (q, 16H), 0.99 (m, 16H), 0.95 (m,

16H), 0.77 (t, 24H); 13C NMR (pyridine- ds, 125 MHz) 5 = 152.9, 152.0, 142.8, 142.2,

141.7, 141.2, 140.0, 138.5, 137.2, 135.1, 128.7, 128.4, 127.9, 127.4, 126.6, 125.1,

124.0, 121.4, 121.0, 119.3, 41.0, 32.1, 30.4, 24.8, 23.2, 14.5; MALDI-TOF MS [M+H]+

2338.2735, calcd 2338.2709.

Platinum Tetraphenyltetranaphthoporphyrin (Pt-40a). The title compound

was prepared from 40a (112 mg, 110.3 pmol) and platinum acetate (150 mg, 109.3

pmol) in benzonitrile (25 mL) using a procedure similar tor Pt-39a heating at 180C. The









crude material was passed a column of neutral silica eluting with DCM:THF (9:1). The

first dark green band was collected and the solvent removed. The material was

precipitated from DCM and acetonitrile. The precipitate was collected and washed

repeatedly with cold MeOH yielding 70 mg of the title compound (53%). The 1H and

gHMBC spectrum of compound Pt-TPTNP were taken on a Varian Inova 500 NMR

spectrometer, equipped with a 5 mm indirect detection probe and with z-axis gradients,

and operating at 500 MHz for 1H and 125 MHz for 13C. The chemical shifts were

referenced to the residual solvent signals, 7.22 ppm in 1H and 123.9 in 13C. Because of

the limited solubility of Pt-TPTNP in the NMR solvent, 13C chemical shifts were

measured by indirect detection, in a gHMBC spectrum. 1H NMR (pyridine- d5, 500 MHz)

5 8.47-8.44 (m, 8H), 8.22-8.14 (m, 4H), 8.10-8.03 (m, 8H), 7.93 (s, 8H), 7.90-7.84 (m,

8H), 7.61 (8H, overlap with solvent); 13C NMR (pyridine- ds, 125 MHz) 5 142.4, 135.9,

134.2, 131.6, 130.5, 130.0, 129.7, 126.7, 124.1, 117.9; ESI-TOF m/z 1206.3188, calcd

1206.3157.

Plati n um 1,4,10,13,19,22,28,31-Octamethoxy-7,16,25,34-tetrakis(3,5-di-tert-

butylphenyl)tetranaphthoporphyrin (Pt-40b). The title compound was prepared from

40b (115 mg, 67.5 pmol) and platinum acetate (92 mg, 67 pmol) in benzonitrile (30 mL)

using the procedure for Pt-39a. The crude material was passed through a column of

neutral silica eluting with DCM. The first dark green band was collected and the solvent

removed. The material was precipitated from warm CHCI3 and MeOH. The precipitate

was collected and washed repeatedly with cold MeOH yielding 110 mg of the title

compound (85%). 1H NMR (pyridine- ds, 500 MHz): 5 = 8.56 (s, 8H), 8.30 (s, 8H), 8.29

(s, 4H), 6.82 (d, 8H), 3.93 (s, 24H), 1.46 (s, 72H); 13C NMR (pyridine- ds, 125 MHz) 5 =









153.6, 151.1, 136.4, 127.5, 125.0, 123.5, 119.7, 119.5, 103.3, 55.8, 35.7, 32.0; MALDI-

TOF MS [M]' 1896.9161, calcd 1896.9090.

Platinum Tetra(3,5-di-tert-butylphenyl)tetraanthroporphyrin (Pt-42) Due to

the sensitivity with oxygen in the presence of room light for the title compound and 42 all

manipulations were preformed under inert atmospheres and flask protected from light

with foil. A schlenk flask charged with benzonitrile (6 mL), 42 (59 mg, 35.5 pmol) and

platinum acetate (48 mg, 35.5 pmol) was degassed by freeze pump thaw cycles. The

mixture was heated at 180C under a positive pressure of argon until the disappearance

of the Q-band of 42 (approx. 3 hours). The solvent was removed by vacuum distillation

and the crude was purified by passing through a short plug of neutral silica under an

argon atmosphere with DCM. The solvent was removed under reduced pressure to give

25 mg of the title compound (38%). 1H NMR (pyridine- d5, 500 MHz): 5 = 8.71 (s, 8H),

8.53 (s, 4H), 8.53 (overlap s, 8H), 8.30 (s, 8H), 8.11 (d, 8H), 7.52 (t, 8H), 1.58 (s, 72H);

13C NMR (pyridine- d5, 125 MHz) 5 = 154.5, 136.6, 132.8, 130.4, 129.1, 128.7, 128.2,

126.3, 125.2, 123.4, 118.5, 35.8, 32.1; MALDI-TOF MS [M]+ 1856.8951, calcd

1856.8872.

Platinum 5,15-Diphenyltetrabenzoporphyrin (Pt-45a). The title compound

was prepared from 45a (50 mg, 75.4 pmol) and platinum acetate (104 mg, 75.7 pmol) in

benzonitrile (25 mL) using the procedure for Pt-39a. The material was loaded on silica,

eluting with DCM removing the green band (45a). The solvent was changed to an

increasing gradient with a THF:DCM mixture (30:70). The dark blue band was collected

yielding 16 mg of the title compound (25%). Analogously to the reported palladium

complex NMR analysis was not possible due to low solubility of Pt-45a in common NMR









solvents.61 The material was characterized by UV-VIS and mass spectrometry. UV-Vis,

Toluene, Amax: 409 nm, 547 nm, 595 nm, 604 nm; MALDI-TOF MS [M]+ 852.4518,

854.1971, 855.2001, 856.2019, 857.2050, 858.2057, 859.2082, 860.2094, 861.4855,

calcd 852.1919, 854.1935, 855.1960, 856.1974, 857.1999, 858.2004, 859.2026,

860.2054.

Platinum 5,15-Di(3,5-di-tert-butylphenyl)tetrabenzoporphyrin (Pt-45b). The

title compound was prepared from 45b (65 mg, 73.3 pmol) and platinum acetate (100

mg, 73.3 pmol) in benzonitrile (30 mL) using the procedure for Pt-39a.The solvent was

removed and the crude material loaded on silica eluting with 15% DCM in Hexane

collecting the blue band. The material was further purified from multiple precipitations

from boiling CHCI3 and MeOH. The precipitate was collected and repeatedly washed

with MeOH yielding 25 mg of the title compound (32%). 1H NMR (pyridine- ds, 500

MHz): 5 = 11.55 (s, 2H), 9.80 (d, 4H), 8.35 (s, 4H), 8.31 (s, 4H), 8.08 (t, 4H), 7.78 (t,

4H), 7.54 (d, 4H); 13C NMR (pyridine- ds, 125 MHz) 5 = 153.1, 141.5, 139.0, 138.2,

136.6, 136.2, 128.1, 127.7, 126.4, 122.8, 121.5, 121.0, 97.5, 35.9, 32.0; ESI-TOF [M]+

1080.4543, calcd 1080.4481.

Platinum 5,15-Di((3,5-di-tert-butylphenyl)-phenyl)tetrabenzoporphyrin (Pt-

45c). The title compound was prepared from 45c (110 mg, 92.3 pmol) and platinum

acetate (127 mg, 92.3 pmol) in benzonitrile (25 mL) using the procedure for Pt-39a.

Separation with column chromatography failed due to solubility and small differences in

Rf values. The title compound was purified by multiple precipitations from DCM and

MeOH to give 70 mg (55%). 1H NMR (pyridine- ds, 500 MHz): 5 = 11.60 (s, 2H), 9.86

(d, 4H), 8.93 (s, 2H), 8.84 (s, 4H), 8.12 (d, 8H), 8.08 (t, 4H), 7.99 (d, 4H), 7.81 (t, 4H),









7.63 (d, 8H), 1.34 (s, 36H); 13C NMR (pyridine- ds, 125 MHz) 5 = 151.8, 143.5, 139.1,

138.3, 138.2, 136.8, 130.5, 128.2, 128.0, 127.8, 126.9, 126.9, 126.3, 121.8, 120.0, 35.0,

31.7; DART-MS [M+H]+ 1383.5772, calcd 1383.5770.

Platinum 5,15-Di(3,5-di-tert-butylphenyl)octapropyltetrabenzoporphyrin (Pt-

45d). The title compound was prepared from 45c (33 mg, 23.2 pmol) and platinum

acetate (32 mg, 23.2 pmol) in benzonitrile (20 mL) using the procedure for Pt-39a. After

vacuum distillation to remove benzonitrile the crude material was loaded on silica and

eluted with a hexane:DCM mixture (85:15) collecting the first blue band. The fractions

were concentrated and the material precipitated by the addition of excess MeOH. The

precipitate was collected to give 22 mg of the title compound (58%). 1H NMR (pyridine-

d5, 500 MHz): 5 = 11.86 (s, 2H), 9.83 (s, 4H), 8.36 (s, 2H), 8.33 (s, 4H), 7.42 (s, 4H),

3.11 (t, 8H), 2.95 (t, 8H), 1.90 (sex, 8H), 1.82 (sex, 8H), 1.63 (s, 36H), 1.18 (t, 12H),

1.12 (t, 12H); 13C NMR (pyridine- ds, 125 MHz) 5 =153.0, 140.7, 140.4, 137.6, 136.8,

127.7, 126.8, 123.5, 121.7, 120.3, 97.0, 36.4, 35.9, 32.2, 25.6, 15.0; ESI-TOF m/z

1416.8265, calcd 1416.8301.










CHAPTER 3
PHOTOPHYSICS AND DEVICE RESULTS

Introduction

Photoluminescence is the process of photons being emitted by either a

fluorophore to give fluorescence or alternatively a phosphor to give phosphorescence

described earlier in Chapter 1. Electroluminescence is the process of generating an

excited state by the application of an electric field and the emission of photons upon

relaxation of the excited species. The first report of electroluminescence was by

Destriau using microcrystals of ZnS suspended in an insulating medium sandwiched

between two electrodes.105' 106 This sparked the development and commercialization of

numerous inorganic materials with a wide variety of emission wavelengths.

A B

Cathode/Aluminum Cathode/Aluminum
Emissive layer/Alq3 Emissive layer/ PPV
Anode / ITO Anode / ITO
Substrate Substrate




Figure 3-1. Single layer device structure for the first reported OLED and PLED. A)
Vapor deposited small molecule OLED with Alq3 as the emissive material. B)
Solution processed polymer based PLED with PPV as the emissive material.

Electroluminescence from organic materials was first described in 1963.107,108 The

use of anthracene crystals as the emitting species resulted in low efficiency and

required high-field strengths and resulted in an overall lack of interest in the use of

organic based materials for electroluminescence. A breakthrough occurred almost

twenty five years later when Tang and Van Slyke reported green emission upon

application of an electric field to single-layer devices fabricated by thermal vapor









deposition of aluminum tris-(-8-hydroxyquinolinate) (AIQ3) onto indium-tin-oxide (ITO)

followed by the thermal vapor deposition of an aluminum electrode shown in Figure 3-

1A.55

Another important milestone was reached in 1990 when the Friend et al prepared

the first polymer light-emitting diode (PLED).109 The device was fabricated from a

sandwiched thin film of poly(p-phenylenevinylene) (PPV) between two electrodes Al and

ITO outlined in Figure 3-1 B. The application of a voltage to the device produced yellow

green light. Thus this work along with the work from Tang and Van Slyke can be

regarded as the seminal works for the development of the organic LED field. The

present day research area of OLEDs and PLEDs has grown significantly with devices in

both areas at the point of commercialization.110-113

Electroluminescence Mechanisms

The simplest description of electroluminescence would be the conversion of

electrons and holes into photons. The actual process can be broken down into four

steps: (1) charge injection into the device, (2) charge transport to the emissive layer, (3)

charge-recombination resulting in the formation of an excited state on the radiative

material and (4) radiative relaxation of the generated excited state. One mechanism for

generating electroluminescence known as intrinsic electroluminescence has been

demonstrated by Bernanose using cellophane films or in perylene and anthracene

crystals.114-116 This requires the acceleration of electrons known as hot carriers to

impact the radiative material generating the excited state. However because high ac

voltages are often required which leads to electrical breakdown, it is difficult to generate

intrinsic electroluminescence in organic materials.









A more successful method of introducing charge carriers into organic materials

involves sandwiching the electroactive materials between electrodes. Application of an

electric field at the electrodes effectively injects electrons and holes into the material.

The use of a low work function metal at the cathode allows for electrons to be easily

injected into the lowest unoccupied molecular orbital (LUMO) and in chemical terms

reduces the electroactive material. This is analogous to injecting electrons into the

conduction band (Ec) of inorganic semiconductors. The cathode is typically made from

calcium, magnesium, or aluminum. Once the electrons are injected into the device near

the cathode, simultaneously the anode injects holes into the highest occupied molecular

orbital (HOMO) of the active material in an analogous fashion to the valence band (Ev)

inorganic semiconductors. The formation of holes or more simply the removal of

electrons is the oxidation of the electroactive material. The anode is most often indium

tin oxide primarily for its high work function and good transmission properties

(transparency) in the visible region. Now that both holes and electrons have been

injected into the active material they begin to drift towards the oppositely charged

electrode. This eventually leads to recombination of both holes and electrons on the

emissive material generating an excited state that may radiatively or non-radiatively

decay.

The choice of whether to use fluorescent or phosphorescent emitters becomes

clear upon examination of the recombination process of electrons with holes. This can

lead to an electron configuration on the emissive material to be either a singlet state (S=

1/) or a triplet state (S=1). Recombination of electrons and holes affords a statistical

distribution of singlet excitons (25%) and triplet excitons (75%). This means that use of










fluorescent emitters (i.e. emission from the Si) are limited to a maximum efficiency of

25%. However the use of phosphorescent materials allows for use of both singlet and

triplet states. Where the singlet states can intersystem cross to the triplet state and then

radiatively decay (phosphorescence) device efficiency can reach the theoretical limit of

100% internal quantum efficiency. Materials with very high phosphorescence quantum

yields are desirable and can potentially be used to fabricate highly efficient PLEDs and

OLEDs.

C.:.ndu:,,b:.n B2nd I LUMMC I
e I i M c on


Cathode
Electron Transport Layer (ETL) 3 >
Emitting Layer o
--- HTL 23 ETL (
Hole Transport Layer (HTL)
Anode
Substrate H
SHole
Injection
Valence Band (HOMO)

Figure 3-2. Device structure of a multilayer light emitting diode with a diagram of
electroluminescence mechanism.

Organic Light Emitting Diodes

The term OLED refers to devices fabricated from the thermal vapor deposition

(sublimation) of small molecules the substrate. The term PLED refers to devices

fabricated from spin coating solution processable polymers on to the substrate.

The electron configuration of the excited material after the recombination of

electrons with holes is not the only contributing factor to device efficiency. The rates at

which the holes and electrons migrate through the materials to eventually recombine on

the desired emitting species are important. Typically in most organic materials the hole









mobility is far higher than the electron mobility. This problem is circumvented by more

complicated device structures with layers of materials that either increase or decrease

the carrier mobilities. An example of this device structure is shown in Figure 3-2.







TPA TPD NPB


Figure 3-3. Examples of small molecule hole transport materials. TPA is triphenylamine,
TPD is (N,N'-diphenyl-N, N'bis(3-methylphenyl)-1, 1'biphenyl-4,4'-amine and
NPB is N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)benzidine.

Electron transport layers (ETL) and hole transport layers (HTL) serve dual

purposes in that they can alter the overall electron and hole mobilities respectively,

while at the same time restricting the transport or injection of the opposite carrier. This

allows the holes and electrons to be trapped in the emissive layer (EML) of the device.

The hole transport layers are generally materials with large energy gaps (AEHOMO-LUMO)

usually consisting of amines with low ionization potentials. These properties allow for

the holes to be more easily injected while also providing a large barrier to electron

injection from the EML. Examples of small molecules that can be vapor deposited for

HTLs are shown in Figure 3-3.







CBP AlI4 MCP

Figure 3-4. Examples of small molecule host materials. CBP is 4,4'-bis(N-carbazolyl)-
1,1'-biphenyl, Alq3 is tris-(8-hydroxyquinoline)aluminum and MCP is 1,3-
bis(carbazol-9-yl)benzene.









The emissive layer of the device can either be a single material (neat) or an

emissive material doped into a polymer or small molecule host at some concentration.

The first OLEDs and PLEDs were fabricated as single layer devices (Figure 3-1).

However it has been shown to be advantageous to use a host material to prevent

various quenching mechanisms induced by having a neat layer of the emitting species.

Common host materials used in the fabrication of OLEDs are outlined in Figure 3-4. The

host materials are paired with the emitting species based on spectral overlap of the host

emission spectrum (usually fluorescence) with the absorption of the emitter. This allows

for efficient Forster energy transfer efficiently quenching the host emission. The

materials may also be prepared such that the HOMO and LUMO of the emitting species

lie within the HOMO and LUMO levels of the host, thus leading to charge trapping on

the emitting species.



B NN





Bphen 3TP r-IB TAZ
Figure 3-5. Examples of small molecule electron transport materials. Bphen is 4,7-
diphenyl-1,10-phenanthroline, 3TPYMB is tris(2,4,6-trimethyl-3-(pyridine-3-
yl)phenyl)borane, and TAZ is 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-
1,2,4-triazole.

In between the cathode and the EML a layer of electron transport materials are

deposited to facilitate balanced charge transport within the device with more efficient

electron injection. In general these materials exhibit high electron mobilities and are

chosen to have deep HOMO energy levels to block hole transport to the cathode.


100









Common materials used for OLED electron transport layers (ETL) are shown in Figure

3-5. The ability to block holes from reaching the cathode helps in trapping the carriers

in the EML for hole and electron recombination on the emissive species.

Polymer Light Emitting Diodes

The devices composed of polymers for either the EML or as a host material are

known as polymer light emitting diodes (PLEDs). Figure 3-6 outlines common polymers

used for these devices. Most of the advantages in using polymeric materials for LEDs

stem from the ability to solution process the materials over the thermal vapor deposition

method used for OLEDs. However, in most cases device efficiencies for PLEDs are

lower than a small molecule based OLED using the same emitter. The main reasons for

the differences in device efficiencies are the difficulty in confining the holes and

electrons to the EML. Since the use of common solvents in processing prevents

deposition of multiple layers, multilayer device architectures in which the holes and

electrons are confined to the active layer are generally not used. Without the addition of

HTL and ETL layers, the carriers in PLEDs can migrate across the device and reach the

opposite electrode without recombination, thus resulting in lower efficiency.



Li N K"



MEH-PPV PFO PVK:PBD

Figure 3-6. Examples of polymer host materials for polymer light emitting diodes. MEH-
PPV is poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], PFO is
poly(9,9-di-n-octylfluorenyl-2,7-diyl and PVK:PBD is poly(9-vinylcarbazole)
blended with 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole.


101









Results and Discussion

Presented herein are the photophysical properties for three series of rr-extended

platinum porphyrins previously outlined in Chapter 2 (Figure 2-2). Also reported are the

performance of these materials in PLEDs and OLEDs using each series of rr-extended

platinum porphyrins as the near-IR phosphors. Specifically this work advances the field

of near-IR LEDs by the realization of electroluminescence in new wavelength regions of

the near-IR using these novel phosphors. For the first time the solution photophysics of

nr-extended platinum porphyrins are reported setting PL efficiency records in their

respective wavelengths regions. Record device efficiencies are obtained from use of

these phosphors for near-IR LED applications.

Series 1- Photophysical Properties

The structures of the free-base and platinum complexes for rr-extended porphyrins

for Series 1are shown in Figure 3-7. The goal of these target compounds is to red shift

the emission wavelengths further into the near-IR through increasing the conjugation to

the porphyrin macrocycle. Platinum complexes for TNP and TAP systems have not

been reported and this work represents the first known report of the photophysical

properties for these targets. Gouterman showed early on that the major effect of

extending conjugation to the porphyrin macrocycle (via fused benzo-rings) was a large

red shift in the Q-band with the transition becoming significantly more allowed (intense),

however only a small red shift is observed for the Soret band.18-20 The absorption and

photoluminescence in air saturated toluene for series 1 free-base porphyrins is shown in

Figure 3-8, while the absorption and emission wavelength maxima, molar absorption

coefficients, emission quantum yields and Si lifetimes are listed in Table 3-1.


102









Series I


GMe moO







Ar = 3,5-di-ber-thulylpheryl
M H2 : H2TPTBP M = M,: HTPTNP M = 1; : H*.Ar4 TPIPIOUMeg M= H : HjTPTBP
M =P Pt P-TPTBP M= Pt: Pt-TPTNP M = Pt- PtAiTNPiOMeuI M = PI: Pt-Ar4TAP


Figure 3-7. Structures for series 1 rr-extended free-base and platinum porphyrins.

The addition of fused-benzo rings to the porphyrin macrocycle from H2TPTBP to

H2Ar4TAP results in approximately a 200 nm red shift of the Q-band. This results in the

transition being shifted from the red region of the visible (H2TPTBP) to being completely

in the near-IR region (H2Ar4TAP). The Q-band becomes more allowed across the series

and is noted by the increase in molar absorptivity constant (E = 3.32 x 104 1.95 x 105

M-1 cm-1) by an order of magnitude from H2TPTBP to H2Ar4TAP. However the Soret

band across the series is only red shifted 50 nm from H2TPTBP to H2Ar4TAP. The

transition is strongly allowed and remains in the visible region of the spectrum (E ~2-3 x

105 M-1 cm-1).

The photoluminescence for series 1 free-base porphyrins were obtained by

excitation of the Soret band (Figure 3-8). The quantum yields (QY) were referenced to

ZnTPP in toluene (QY 0.04)117 while the Si decays were obtained by single photon

counting and were all mono-exponential in nature shown in Figure A-1. A small Stokes

shift is observed with the S- emission maxima relative to the lowest energy absorption.

The emission maxima are red shifted approximately 140 nm (H2TPTBP to H2Ar4TAP)

across the series. The quantum yield for H2TPTBP in toluene is in agreement with the


103









reported literature value.61 The increase in the QYs for H2TPTNP and H2Ar4TNP(OMe)8

reflect the increase in kr values consistent with an increase in the allowedness of the Si-

So transition, and in line with other values reported for H2Ar4TNP systems.58 Ono et al

have reported the PL spectra for two fluorescent ZnTAPs, however photophysical

characterization of a free-base TAP has not been reported.66 The PL for H2Ar4TAP is

dominated by emission at 841 nm with a vibronic should at 932 nm. The low intensity

broad emission in the visible region is likely from the anthracene fragments in the TAP

macrocycle. The QY for H2Ar4TAP (6.8%) is higher than the reported QYs for ZnTAPs

(3.7-4.3%) which are expected to be lower due to the increase rate in ISC.

Table 3-1. Photophysical properties of Series 1 free-base rr-extended porphyrins in air
saturated toluene. Fluorescence quantum yields were measured relative to
ZnTPP (0.04) with excitation at 420 nm in toluene. The S1 decays were
obtained by single photon counting method.
Absorption
Free-base Amax (Soret, Q-band) Fluorescence
Porphyrins nm Amax nm (pf Tf (ns)
(Emax = M-1 cm1)

H2TPTBP 465, 633 704, 785 4.1% 0.1 3.1
E465 = 3.03 x 105
E633= 3.32 x 104

H2TPTNP 500, 728 756, 840 19% 0.2 3.9
s500 = 2.25 x 105
E728= 1.06 x 105

H2Ar4TNP(OMe)8 502, 730 755, 837 23% 0.1 4.6
E502 = 2.64 x 105
E730= 1.18 x 105

H2Ar4TAP 510,824 841,932 6.8% 0.5 1.0
E51o = 2.11 x 105
E824= 1.95 x 105

The decrease in the Si lifetime and quantum yield for H2Ar4TAP compared to

H2TPTBP follows the energy gap law.118 119 This states that as the difference in energy

between the ground state and excited state gets smaller the rate of non-radiative decay


104









will increase, thus decreasing the radiative rate and QY. The deactivation rate

constants for the Si state for series 1 free-base rr-extend porphyrins were calculated

and summarized in Table 3-2. The radiative rate constant (kr) across the series

increases from H2TPTBP to H2Ar4TAP about 5.2 times. The non-radiative rate constant

(knr) also increases across the series about 3 times. This results in the observed

decrease in Si lifetimes across the series.

Table 3-2. Deactivation rate constants for Si state of series 1 free-base rr-extended
porphyrins in air saturated toluene. Radiative decay rate constant (kr),
calculated as kr= qpfk, and the non-radiative decay rate constant (knr = kic +
kisc), calculated as kr = k knr.

Free-base k = 1/Tf (S-1) k, (S-1) knr (-1) Tf (ns)
Porphyrins

H2TPTBP 3.2 x 108 1.3 x 107 3.1 x 108 3.1

H2TPTNP 2.6 x 108 4.9 x 107 2.1 x 108 3.9

H2Ar4TNP(OMe)8 2.2 x 108 5.1 x 107 1.7 x 108 4.6

H2Ar4TAP 1.0 x 109 6.8 x 107 9.3 x 108 1.0

The absorption and photoluminescence in deoxygenated toluene for series 1 n-

extended platinum porphyrins is shown in Figure 3-9. The absorption and emission

wavelength maxima for the series are summarized in Table 3-3 along with the molar

absorption coefficients, phosphorescence QYs and T1 lifetimes.

The insertion of platinum changes the porphyrin symmetry to D4h. The absorption

spectra are blue shifted relative to the respective free-base absorptions. This is due to

the donated d-electrons from platinum into the -n*-orbitals of the porphyrin resulting in

metal-to-ring charge transfer giving irregular hypso-type spectra. The relative intensities

between the Soret and Q-bands have also changed. The insertion of the metal makes

the Q-band transition more allowed (E ~4-5 x 104 1-2 x 105 M1 cm-1). In the case of


105








platinum TNP and TAP systems the Q-band surpasses the Soret in intensity giving very


strong absorptions in the deep-red to near-IR region of the spectrum.


400


600


800


1000


Wavelength (nm)

Figure 3-8. Normalized absorption (black) and photoluminescence (red) of Series 1
free-base rr-extended porphyrins in toluene: A) H2TPTBP, B) H2TPTNP, C)
H2Ar4TNP(OMe)8, D) H2Ar4TAP.


106









Table 3-3. Photophysical data for series 1 rr-extended platinum porphyrins in
deoxygenated toluene. Quantum yields were measured relative to ZnTPP
(0.04) by excitation at 420 with the exception of Pt-Ar4TAP which was
measured relative to H2TPTBP (0.041) with excitation at 420 nm. The T1
lifetimes were obtained by transient absorption spectroscopy.
Absorption
Platinum Amax (Soret, Q- Phosphorescence
Porphyrins band) nm Amax nm Ophos TT-T (ps) EST (eV)
(Emax = M-1 cm-1)

Pt-TPTBP 430, 612 773 46% 5 29.9 0.33
E430 = 1.91 x 105
E612= 1.35 x 105

Pt-TPTNP 436,689 891 20% 0.1 12.7 0.34
E436 = 9.17 X 104
E689= 1.50 X 105

Pt- 455, 690 883 16% 0.5 15.3 0.32
Ar4TNP(OMe)8 E455 = 8.30 x 104
E690= 1.32 x 105

Pt-Ar4TAP 455,762 1022 11% 2 3.2 0.35
E455 = 2.99 x 104
E762= 4.64x 104

Table 3-4. Deactivation rate constants for T1 state of series 1 rr-extended platinum
porphyrins in deoxygenated toluene. Radiative decay rate constant (kr),
calculated as kr= qphosk, and the non-radiative decay rate constant (knr = kic +
kisc), calculated as kr = k knr.

Platinum k = 1/TT-T (-1) k, (s-) knr (-1) TT-T (ps)
Porphyrins

Pt-TPTBP 3.3 x 104 1.5 x 104 1.8x 104 29.9

Pt-TPTNP 7.9 x 104 1.6 x 104 6.3 x 104 12.7

Pt- 6.5 x 104 1.0 x 104 5.5 x 104 15.3
Ar4TNP(OMe)8

Pt-Ar4TAP 3.1 x 105 3.5 x 104 2.8 x 105 3.2

The photoluminescence spectra from series 1 rr-extended platinum porphyrins are

dominated by a single phosphorescence band with a weak vibronic shoulder. The

platinum center dramatically increases the rate of ISC from Si to the T1 state via the


107









heavy atom effect. The porphyrins are now strongly phosphorescent and no longer

fluorescent. Moving across the series from Pt-TPTBP to Pt-Ar4TAP the expected trend

based on the energy gap law of a decrease in both the lifetime and quantum yield are

observed. The Singlet-Triplet energy splitting (EST) was calculated from approximating

the singlet energy level at the onset of the lowest energy Q-band and the emission

maximum and remains relatively constant across the series. The non-radiative rate

constant (Table 3-4) increases about 3 times from Pt-TPTBP to the Pt-TNPs and for Pt-

Ar4TAP is an order of magnitude higher compared to Pt-TPTBP. The QYs were

measured in deoxygenated toluene using ZnTPP as an actinometer, except for Pt-

Ar4TAP which was measured relative to H2TPTBP. The T1 lifetimes were determined

from transient absorption spectroscopy.

The photoluminescence spectrum for Pt-TPTBP is identical to that reported in the

literature. The reported quantum yield and lifetime (53 ps, 0.70) for Pt-TPTBP by

Thompson et al are different from our measurements (29.9 ps, 0.43) but in line with

those from Kilmant et a/.53 57 However, absent from the literature was a report for a

platinum TNP and its photophysical properties. The PL spectra for Pt-TPTNP is red

shifted (-100 nm) relative to Pt-TPTBP. The quantum yield (0.20) and lifetime (12.7 ps)

are lower compared to that of Pt-TPTBP. Based on a literature report for a palladium

octamethoxy substituted TNP it was expected that the PL for Pt-Ar4TNP(OMe)8 would

be red shifted relative to Pt-TPTNP; however this is not observed. The red shift reported

in the literature is believed to originate from a push-pull effect created by ester

substituents (electron withdrawling) in the 3,5-positions in the meso-aryl substituents.120


108









1.0
A
0.8
0.6
0.4


0.0
1.0
0.8
S 0.6
0.4
0.2
-O 0.0 I ,
S 1.0
-F 0.8
o 0.6
Z
0.4
0.2
0.0
1.0 D
0.8
0.6
0.4
0.2
0.0
400 600 800 1000 1200

Wavelength (nm)

Figure 3-9. Normalized absorption (black) and photoluminescence (red) for series 1 rr-
extended platinum porphyrins in toluene: A) Pt-TPTBP, B) Pt-TPTNP, C) Pt-
Ar4TNP(OMe)8, D) Pt-Ar4TAP.

A Pd-TAP derivative has been reported without PL spectra (phosphorescence) in

the literature with a QY of less than 0.5% with emission reported at 1.12 eV (1107 nm).


109









To our knowledge this represents the first full report and photophysical characterization

of a phosphorescent TAP and more specifically a platinum TAP. The PL spectrum for

Pt-Ar4TAP is centered at 1022 nm with a life time of 3.2 ps measured by transient

absorption spectroscopy. The phosphorescence QY was measured relative to

H2TPTBP as the Soret bands are separated by ~20 nm and Si emission (704,788 nm)

is in a region of good sensitivity for the near-IR detector. The QY measured for Pt-

Ar4TAP was 11%. Multiple measurements could not be made from the same solution as

severe bleaching occurred and so error bars of ~20% are assumed. Nonetheless the

room temperature phosphorescence yields of series 1 rr-extended platinum porphyrins

represent the highest that have ever been reported for materials that emit at

approximately ~800, 900, and 1000 nm regions of the near-IR.

Series 1- PLED Device Results

PLEDs were fabricated by the Reynolds group (Ken Graham) at the University of

Florida. Spin-coating the active layer on top of a PEDOT:PSS layer, followed by

evaporation of the metal electrode materials to give the following device structure:

glass/ITO/PEDOT: PSS(40 nm)/2% Pt-porphyrin:PVK: PBD(7:3) (110 nm)/LiF(1

nm)/Ca(10 nm)/AI. However, PLEDs fabricated with this device structure displayed very

poor performance for Pt-Ar4TAP. A hybrid device structure adopted by thermal vapor

deposition of an ETL (Bphen) to give a new device structure of

glass/ITO/PEDOT:PSS(40 nm)/PVK:PBD(7:3):2% Pt-Ar4TAP(110 nm)/Bphen(40

nm)/LiF(1 nm)/AI was used in efforts to increase device efficiency.

Electroluminescence (EL) across the series for series 1 PLEDs is centered at 771,

898, 892, and 1005 nm for Pt-TPTBP, Pt-TPTNP, Pt-Ar4TNP(OMe)8, and Pt-Ar4TAP

respectively with no host emission observed (Figure 3-10A). Light emission from the


110











PLEDS turns on at an applied voltage of ~8-17 V observed in the R-V plot (Figure 3-


10C). Similar current densities are observed in the J-V plot (Figure 3-10B) but expected


as only the near-IR phosphor is changing in the device structures. Overall the PLEDs


operate at relatively high voltages due to the thickness of the emissive layer and the


high electron and hole injection barriers.


800 1000 1200
Wavelength (nm)


le+3

le+2 B

-1e+1

C 1 e+0

E le-1

le-2

le-3 *
so
le-4
0 5 10 15
Voltage (V)


20 25


1.6
1.4 D .* *

1.2
1.0

CO 0.8

- 0.6 **. *.
0.4

0.0 "" "' """
o~oiS^t'**' '**^^^^"." ^.N- __


5 10 15 20 25 le-1 le+0 le+1 le+2

Voltage (V) J (mA/cm2)


Figure 3-10. PLED device results for series 1 rr-extended platinum porphyrins. Pt-
TPTBP (black), Pt-TPTNP (red), Pt-Ar4TNP(OMe)8 (green), and Pt-Ar4TAP
(blue) with the following device structure: glass/ITO/PEDOT:PSS(40 nm)/2%
Pt-porphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/AI. A) EL spectra
for PLEDs, B) J-V plot, C) R-V plot, D) External quantum efficiency.

Although the hybrid PLED device structure for Pt-Ar4TAP has a significantly lower turn


on voltage due to the ETL (Figure 3-11 B). The PLEDs across the series exhibit


111


1.2

1.0

0.8

0.6

0.4

0.2

0.0
600


le+4


le+3
C14
E
O le+2


Sle+1


le+0


le-1











maximum radiant emittance of approximately 100-1000 pW/cm2. The maximum external


quantum efficiencies (EQE) for the series range from 0.04-1.5%. The PLED fabricated


from Pt-TPTBP gave the highest EQE while Pt-Ar4TAP gave the lowest EQE of 0.04%


shown in Figure 3-10D. The Pt-TPTNP and Pt-Ar4TNP(OMe)8 based PLEDs gave


maximum EQE values of 0.74 and 0.36%.


800 900 1000
Wavelength (nm)


1100 120


"N
* *o,0
** ** e~o


le+4
le+3 B
le+2

E
C. le+1
S1 e+0 **
E le-1
e- le-2
le-3
le-4
le-5 500O woq o W ..
0 0 2 4 6 8 10 12 14 1
Voltage (V)


w 02


01


00


le+2

le+1
0(
le+0 E

1e-1

1e-2

le-3

le-4


**,,


le-1 le+0 le+1 le+2 le+3 le-1 le+0 le+1 le+2 le+3

J (mA/cm2) J (mA/cm2)


Figure 3-11. Hybrid PLED device for Pt-Ar4TAP with device structure:
glass/ITO/PEDOT:PSS(40 nm)/PVK:PBD(7:3):2% Pt-Ar4TAP(110
nm)/Bphen(40 nm)/LiF(1 nm)/AI. A) EL spectrum, B) J-V plot (closed circles)
and R-V (open circles), C) Power efficiency, D) External quantum efficiency.

The device performance of Pt-Ar4TAP in the hybrid PLED device structure is


shown in Figure 3-11. EL from the device is identical to that from the Pt-Ar4TAP based


PLED (Figure 3-11A). The device featured maximum radiant emittance of -1 mW/cm2 at


approximately 12 volts shown in Figure 3-11B. The maximum EQE value (Figure 3-11D)


112


12

1 0

08

06

04

02

00
700


06 C
05

0 04
E
v03
0-
S02

01
00









for the hybrid device was ~0.25 which is around 5 times higher than the Pt-Ar4TAP

based PLED.

Series 1- OLED Device Results

Due to the high molecular weight of Pt-Ar4TNP(OMe)8 and Pt-Ar4TAP thermal

vapor deposition for OLEDs was not possible. Thus, OLEDs were only constructured

using Pt-TPTBP and Pt-TPTNP. Thompson et al have previously reported an OLED

using Pt-TPTBP as the near-IR phosphor with an overall EQE of 8.5%.53, 67 Multilayer

OLEDs were fabricated by the Xue group at the University of Florida (Yixing Yang) with

Pt-TPTBP having the following device structure: ITO/NPB(40 nm)/Alq3:4% Pt-TPTBP(25

nm)/Bphen(80 nm)/LiF(1 nm)/AI. Another multilayer device was fabricated with Pt-

TPTNP representing the first reported use of this material in an OLED with the following

device structure: ITO/NPB(40 nm)/CBP:8% Pt-TPTNP(20 nm)/Bphen(100 nm)/LiF(1

nm)/AI.

Electroluminescence from the Pt-TPTBP and Pt-TPTNP OLEDs is centered at 773

nm and 890 nm, respectively, similar to the EL for the respective PLEDs (Figure 3-12A).

The R-V plot (Figure 3-12B) shows that light emission for both devices is observed at a

rather low turn on voltage of ~2 V. The maximum radiant emittance for the Pt-TPTBP

based OLED is 1 mW/cm2 obtained at ~12V (Figure 3-11B). Similarly the maximum

radiant emittance of the Pt-TPTNP based OLED is 1 mW/cm2 obtained at ~10 V (Figure

3-11B). The EQE data shown in Figure 3-12D for the OLED fabricated with Pt-TPTBP

gave a maximum EQE of 8.0%, in good agreement with the literature value of 8.5%.

The Pt-TPTNP based OLED displays a maximum EQE of 3.8%. The lower EQE of a Pt-

TPTNP based OLED relative to a Pt-TPTBP based OLED follows the trend for the

phosphorescence QYs and lifetimes of the materials (3.8%, 0.201, and 12.7 ps) and


113










(8.0%, 0.459, and 29.9 ps) respectively. Although the EQE value for Pt-TPTNP based

OLEDs is lower it represents a new record for devices emitting beyond 800 nm.

12 le+4 le+4
1e+3 1e+3
1 0 A le+2 le+2
e+2e+1
LU le+1 C
"08 \\ 0\ < l e+o 1e+1 C4l
08 le+0 E
Sle-1 le+0
06 1le-2 le-1
EE l e-3 le-2 E
04 le-4 le-3
Z le-5
02 le-6 le-4
1 e-7 le-5
00 le-8 ... le-6
600 700 800 900 1000 0 2 4 6 8 10 12 14 16 18
Wavelength (nm) Voltage (V)
60 10

50 C D

40

E 30 *

20 2

10

0 0
1e-4 1e-3 1e-2 le-1 le+0 le+1 1e+2 le+3 1e-4 1e-3 1e-2 le-1 le+0 le+1 1e+2 1e+3

J (mA/cm2) J (mA/cm2)

Figure 3-12. OLED device results for series 1 rr-extended platinum porphyrins. Pt-
TPTBP (black), Pt-TPNP (red), with device structures: glass/ITO/NPB(40
nm)/Alq3:4% Pt-TPTBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/AI and
glass/ITO/NPB(40 nm)/CBP:8% Pt-TPTNP(20 nm)/Bphen(100 nm)/LiF(1
nm)/AI. A) EL spectra for OLEDs, B) J-V plot (closed circles) and R-V (open
circles), C) Power efficiency, D) External quantum efficiency.

Series 2- Photophysical Properties

The recent report of Pd-5,15-diaryl-TBPs by Vinogradov et al is the primary basis

for developing the free-base and Pt-TBPs for series 2 outlined in Figure 3-13.61 They

report the solution phosphorescence QY for Pd-DPTBP to be twice that of Pd-TPTBP

and half that of a soluble meso-unsubstituted Pd-TBP. This trend is observed due to an

increase in macrocycle planarity which decreases the non-radiative decay rate thus


114









increasing the lifetime and QY. Ikai et al have also reported that 3,5-di-tert-butylphenyl

meso-aryl substituents provide facial sterics leading to enhanced device efficiency in

platinum porphyrin based LEDs.78 The following series was developed to expand the

known literature work on Pt-TBPs. It is expected, that the Pt-5,15-diaryl-TBPs will

exhibit a QY twice that of Pt-TPTBP and Pt-Ar4TBP based on an increase in the

planarity of the macrocycle. Also examined are the effect of bulky meso-aryl

substituents (3,5-tBuPh) on device efficiency across the series. This represents the first

known report for the synthesis and photophysical characterization of platinum 5,15-

diaryl-TBPs.

Series 2




N N





M H2 : H2TPTBP M H1: H2Ar4TBP M Ha I: HDPTBP M I H: HIArTBP
M Pt: Pt-TPTBP M m Pt: Pi-ArjTBP M PI: Pt-DPTBP M Pt : Pt-ArzTBP

Figure 3-13. Structures of free-base and platinum complexes for series 2 TBPs.

The absorption and photoluminescence in air saturated toluene for series 2 free-

base TBPs is shown in Figure 3-14. The absorption spectra for H2TPTBP and H2DPTBP

are identical to those previously reported in the literature. The absorption spectra for

H2Ar4TBP and H2Ar2TBP are identical to the respective phenyl derivatives with only a

small red shift observed (1-2 nm) in each case. In both diaryl- and tetraryl-TBPs the

Soret band is strongly allowed in the visible region with high molar absorptivity values

(2-3 x 105 M-1 cm-1). The absorption spectra for H2DPTBP and H2Ar2TBP show well


115









resolved vibronic structure in both the Soret and Q-band. The large splitting (841 cm-1)

in the Soret band of 5,15-diaryl TBPs is attributed to the strong mixing of the Soret and

Q-band states.19' 121,122 These spectra resemble red shifted meso-unsubstituted TBPs

and strongly suggest there is little difference in macrocycle planarity between 5,15-diaryl

TBPs and meso-unsubstituted TBPs. This increase in planarity results in both the

absorption and PL being sharper and blue shifted relative to the tetraaryl derivatives.

The photophysical data for series 2 free-base TBPs is summarized below in Table 3-5.

Table 3-5. Photophysical properties of Series 2 free-base TBPs in air saturated toluene.
Fluorescence quantum yields were measured relative to ZnTPP (0.04) with
excitation at 420 nm in toluene. The Si decays were obtained by single
photon counting method.
Absorption
Free-base Amax (Soret, Q-band) nm Fluorescence
Porphyrins (Emax = M-1 cm-1) Amax nm (pl Tfi (ns)

H2TPTBP 465, 633 704, 785 4.1% 0.1 3.1
E465 = 3.03 x 105
E633= 3.32 x 104

H2Ar4TBP 462,630 701,779 4.3% 0.1 3.5
E462 = 3.21 x 105
E630= 4.14 x 104

H2DPTBP 440,612 671,738 37% 4.0 10.6
E440 = 3.62 x 105
E612= 6.81 x 104

H2Ar2TBP 440,612 671,738 38% 4.0 10.3
E440 = 3.83 x 105
E612= 6.70 x 104

The absorption and photoluminescence in deoxygenated toluene for series 2

platinum TBPs is shown in Figure 3-15. The photophysical data for series 2 platinum

TBPs is summarized and reported in Table 3-7. The absorption spectra for series 2

platinum TBPs are blue shifted relative to the free-base TBPs and indicative of

porphyrins with local D4h symmetry (metal center).


116









Table 3-6. Deactivation rate constants for S1 state of series 2 free-base TBPs in air
saturated toluene. Radiative decay rate constant (kr), calculated as kr = qclk,
and the non-radiative decay rate constant (knr = kic + kisc), calculated as kr = k
knr.

Free-base k = 1/Tf (S-1) k, (S-1) knr (-1) Tfl (ns)
Porphyrins

H2TPTBP 3.2 x 108 1.3 x 107 3.1 x 108 3.1

H2Ar4TBP 2.9 x 108 1.2 x 107 2.7 x 108 3.5

H2DPTBP 9.4 x 107 3.5 x 107 5.9 x 107 10.6

H2Ar2TBP 9.7 x 107 3.7 x 107 6.0 x 107 10.3

Table 3-7. Photophysical data for series 2 platinum TBPs in deoxygenated toluene.
Quantum yields were measured relative to ZnTPP (0.04) by excitation at 420
nm in toluene. The T1 lifetimes were obtained by transient absorption
spectroscopy.
Absorption
Platinum Amax (Soret, Q-band) Phosphorescence
Porphyrins nm Amax nm Ophos TT-T (pS)
(Emax = M-1 cm-1)

Pt-TPTBP 430, 612 773 46% 5 29.9
E430 = 1.91 x 105
E612= 1.35 x 105

Pt-Ar4TBP 432, 610 772 44% 0.3 32.0
E432 = 1.81 x 105
E610= 1.05 x 105

Pt-DPTBP 409, 604 770 40% 2 28.0
E409 = 2.68 x 104
E604= 2.13 x 104

Pt-Ar2TBP 410, 604 770 65% 8 53.0
E410 = 1.73 x 105
E604= 1.32 x 105

As expected the absorption spectra for Pt-TPTBP and Pt-Ar4TBP are virtually identical.

The vibronic structure observed in the Q-bands for platinum 5,15-diaryl TBPs most likely

results from the unsymmetrical nature of the macrocycle. As stated earlier the insertion

of the metal makes the Q-band transition more allowed with the molar absorptivity


117










constants in the platinum 5,15-diaryl TBPs being -20% higher than Pt-TPTBP or Pt-

Ar4TBP. The Soret band is the most intense transition (1-2 x 105 M-1 cm1) across the

series in the absorption spectra located in the visible region. The very low solubility of

Pt-DPTBP is likely the reason for the low E value.


1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0


1.0
0.8
0.6
0.4
0.2
0.0
3(


400


500


600


700


800


900


Wavelength (nm)

Figure 3-14. Normalized absorption (black) and photoluminescence (red) of series 2
free-base TBPs in toluene: A) H2TPTBP, B) H2Ar4TBP, C) H2DPTBP, D)
H2Ar2TBP.


118


D


00











0.8
0.6
0.4
0.2
0.0
1. B
0.8
0.6
0.4
0.2
c 0.0
N 1.0
E0.8
o 0.6
Z
0.4
0.2
0.0

0.8
0.6
0.4
0.2
0.0
400 600 800 1000

Wavelength (nm)

Figure 3-15. Normalized absorption (black) and photoluminescence (red) for series 2
platinum TBPs in toluene: A) Pt-TPTBP, B) Pt-Ar4TBP, C) Pt-DPTBP, D) Pt-
Ar2TBP.


119









The photoluminescence spectra for series 2 platinum TBPs are shown in Figure 3-

15. The PL spectra are dominated by a single phosphorescence band with a weak

vibronic shoulder. The maximum emission wavelengths for Pt-TPTBP and Pt-Ar4TBP

are centered at 773 and 772 nm respectively. The PL spectra for Pt-DPTBP and Pt-

Ar2TBP are slightly blue shifted (770 nm) and have a narrower full width at half

maximum (FWHM) due to the increased planarity of the TBP macrocycle. The T1

lifetimes for the entire series were measured by transient absorption spectroscopy. The

values for Pt-TPTBP and Pt-Ar4TBP as expected gave very similar T1 lifetimes of 29.9

and 32.0 ps respectively. The QYs should be very similar as they are directly

proportional to the lifetimes. The QYs were measured relative to ZnTPP (0.04) in

toluene for Pt-TPTBP and Pt-Ar4TBP to give values of 0.46 and 0.44 respectively. This

is in good agreement with the lifetime data and reported values.57

However the lifetime and QY measured for Pt-DPTBP was not expected based on

the recent trend observed in the Pd-TBPs reported by Vinogradov et al discussed

herein elsewhere. The T1 lifetime (28.0 ps) and phosphorescence QY (0.40) for Pt-

DPTBP are nearly identical to Pt-TPBP and Pt-Ar4TBP. The QY was expected to

increase (~double) due to the increased macrocycle planarity and reduction of the non-

radiative decay rate (Table 3-8). However, other literature reports exist suggesting that

the rotation of the meso-phenyl substituent serves as a non-radiative decay path way

negating the effects of increased planarity.43' 78 Once this rotation is blocked (i.e. bulky

group) the observed T1 lifetime increases as in the case of Pt-Ar2TBP (53.0 ps). The QY

for Pt-Ar2TBP (0.65) has been measured as high as 0.90 but difficulty exists in

reproducing this measurement. A decrease in the non-radiative decay rate (knr) from


120









the increased planarity is observed (Table 3-8). Pt-Ar2TBP has the highest PL efficiency

ever reported for a phosphor in this wavelength region.

Table 3-8. Deactivation rate constants for T1 state of series 2 platinum TBPs in
deoxygenated toluene. Radiative decay rate constant (kr), calculated as kr =
CPphosk, and the non-radiative decay rate constant (knr = kic + kisc), calculated
as kr = k- knr.

Platinum k = 1/TT-T (S-1) k, (S-1) knr (S-1) TT-T (pS)
Porphyrins

Pt-TPTBP 3.3 x 104 1.5 x 104 1.8 x 104 29.9

Pt-Ar4TBP 3.1 x 104 1.4 x 104 1.8 x 104 32.0

Pt-DPTBP 3.6 x 104 1.4 x 104 2.1 x 104 28.0

Pt-Ar2TBP 1.9 x 104 1.2 x 104 6.5 x 103 53.0

Series 2- PLED Device Results

PLEDs were fabricated by spin-coating the active layer on top of a PEDOT:PSS

layer, followed by evaporation of the metal electrode materials to give the following

device structure: glass/ITO/PEDOT:PSS(40 nm)/2% Pt-porphyrin:PVK:PBD(7:3) (110

nm)/LiF(1 nm)/Ca(10 nm)/Al. Due to the limited solubility of Pt-DPTBP it was excluded

from device fabrication.

Electroluminescence from the PLEDs is centered at ~770 nm with no host

emission observed (Figure 3-16A). Light emission from the PLEDS turns on at an

applied voltage of ~12 V observed in Figure 3-16C. Overall the PLEDs operate at

relatively high voltages due to the thickness of the emissive layer (110 nm) and the high

electron and hole injection barriers. The PLEDs exhibit maximum radiant emittance of

approximately 1000 pW/cm2 (Figure 3-16C). The maximum external quantum

efficiencies for the series range from 1.0-1.5%. The PLED fabricated from Pt-TPTBP

gave the highest EQE (1.50%) while Pt-Ar4TBP gave a slightly lower EQE of 1.05%.


121











Although Pt-Ar2TBP has a much higher solution phosphorescence quantum yield the


PLED EQE is slightly lower (1.43%) than that of Pt-TPTBP.


1.2 -l-- 1e+3

1.0A le+2 B

0 0.8 l4e+
N, E
C) 1e+o
oU 0.6 le+<
E E le-1 "

Z le-2 *
0.2
1e-3
0.2 le-3 *

0.0 -- le-4 .
600 700 800 900 1000 0 5 10 15 20 25
Wavelength (nm) Voltage (V)


1.6
1.4 Ds
1.2
1.0
03 0.8
F- 0.6
0.4
0.2 S
0.0 ='-~ -' .- : .7i......


I 'I


5 10 15 20 25 le-1 le+0 le+1 1e+2
Voltage (V) J (mA/cm2)


Figure 3-16. PLED device results for series 2 platinum TBPs. Pt-TPTBP (black), Pt-
Ar4TBP (red), and Pt-Ar2TBP (green) with the following device structure:
glass/ITO/PEDOT:PSS(40 nm)/2% Pt-porphyrin:PVK:PBD(7:3) (110
nm)/LiF(1 nm)/Ca(10 nm)/Al. A) EL spectra, B) J-V plot, C) R-V plot, D)
External quantum efficiency.

Series 2- OLED Device Results

Multilayer OLEDs were fabricated from thermal vapor deposition to give the


following device structure: glass/ITO/NPB(40 nm)/Alq3:4% Pt-TBP(25 nm)/Bphen(80


nm)/LiF(1 nm)/AI for series 2 platinum TBPs. Electroluminescence from the OLEDs is


centered at ~770 nm and is shown in Figure 3-17A. Light emission is observed at a


122


le+4

le+3
C14
E
0 1e+2

"- 1e+1


le+0

le-1


C





C
*
*
S


*










rather low turn on voltage of ~2 V with the maximum radiant emittance of 1 mW/cm2

obtained at ~12V (Figure 3-17B). The current densities across the series are similar and

expected due to little difference in the device structure with the only changes coming

from substituent patterns in the platinum TBPs (Figure 3-17B).

1.2 le+4 le+4
A 1 e+3 B 1e+3
1.0 le+2
J 1 e+1 e+2
U 0.8 E le+0 le+1
N le-1 e+0
"U 06 0.6 le-2
E Ele-3
O 0.4 le-4 le2 e
Z le-5 le-3
0.2 le-6
le-7 0 le-4
0.0 le-8 1 e-5
600 700 800 900 1000 0 2 4 6 8 10 12 14
Wavelength (nm) Voltage (V)
60 10


4 0 6



S20

10
0 0
le-4 le-3 le-2 le-1 le+0 le+1 le+2 le+3 le-4 le-3 le-2 le-1 le+0 le+1 le+2 le+3
J (mA/cm2) J (mA/cm2)

Figure 3-17. OLED device results for series 2 platinum TBPs. Pt-TPTBP (black), Pt-
Ar4TBP (red), Pt-DPTBP (green), and Pt-Ar2TBP (blue) with device structure:
glass/ITO/NPB(40 nm)/Alq3:4% Pt-TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/AI.
A) EL spectra for OLEDs, B) J-V plot (closed circles) and R-V (open circles),
C) Power efficiency, D) External quantum efficiency.

The EQE data shown in Figure 3-17C for the series follows a different trend than

the PLED EQE data. In contrast to the PLED data, Pt-Ar4TBP gave a higher maximum

EQE (9.2%) than Pt-TPTBP (8.0%). Although Pt-DPTBP was not soluble enough for

PLED fabrication it was readily incorporated into a multilayer OLED giving a maximum


123









EQE of 5.0%. The significantly lower efficiency is likely due to bimolecular interactions

or aggregates of Pt-DPTBP within the host matrix. Interestingly the T1 lifetimes and

phosphorescence QYs for Pt-TPTBP, Pt-Ar4TBP and Pt-DPTBP are nearly identical.

However, these materials give maximum OLED EQEs ranging from 5.0-9.2%. The

differences in efficiency are likely due to some physical property of the porphyrin or

porphyrin:host morphology.

Thompson et al have shown that platinum porphyrins with high phosphorescence

QYs like Pt-OEP (0.45) give higher maximum EQEs (1.3%) in OLEDs compared to Pt-

DPP (0.16, 0.25%).43 However, despite the significant increase in the solution QY for Pt-

Ar2TBP the maximum EQE (7.8%) is comparable to that of Pt-TPTBP (8.0%).

Series 3- Photophysical Properties

The EQE data for series 2 OLEDs strongly suggest some form of aggregation of

the phosphor or phosphor: host incompatibility from a morphology standpoint. Recent

literature reports of both porphyrin systems and other dyes have displayed improvement

in device efficiencies through the addition of bulky substituents.69 71, 73, 77, 78 This creates

a dye encapsulation effect that prevents self-quenching mechanisms. The platinum

TBPs in series 3 were designed in order to examine the effects of bulky substituents on

the photophysical properties and device efficiencies shown and are shown Figure 3-18.

The absorption and photoluminescence in air saturated toluene for series 3 free-

base TBPs is shown in Figure 3-19. The absorption and emission wavelength maxima

for series 3 free-base TBPs are summarized in Table 3-9 along with the molar

absorption coefficients, QYs and Si lifetimes. The Soret and Q-band for H2ArF4TBP are

each red shifted about 10 nm and they resemble the absorption spectrum for H2TPTBP.


124








Series 3


M = H : H2ArFj4BP M = H2 : H2TAr2TBP M = 2H HzAr2OPrTBP
M = Pt; PtArF'TBP M = Pt: Pt-TAr2TOP M = Pt: Pt-ArOPrTBP


Figure 3-18. Structures of free-base and platinum complexes for series 3 TBPs.

This trend is similar to the reported H2TPP and H2TPP-Fluorenyl derivatives.77 Aside

from the red shift in the Soret and Q-band the addition of the fluorenyl-substituents

contributes to an additional absorption at ~300 nm. The Soret bands for H2TAr2TBP and

H2Ar20PrTBP both display a small red shift of 2 and 5 nm respectively relative to

H2DPTBP. The Q-bands however are not red shifted and identical to H2DPTBP. The

molar absorptivity values measured for series 3 free-base TBPs are in line with the

values obtained for series 2.

The PL spectra in air saturated toluene are shown in Figure 3-19. The emission

maxima for H2ArF4TBP is red shifted 7 nm relative to H2TPTBP. The lower energy band

is also significantly higher in intensity than in H2TPTBP (Appendix A-6). This suggests

the fluorenyl-substituents are increasing the saddling of the TBP macrocycle leading to

the observed shorter lifetime. Consequently a smaller quantum yield relative to


125









H2TPTBP would be expected however the increase is probably attributed to a reduction


in solution interactions similar to the reported TPP derivatives.


Table 3-9. Photophysical properties of Series 3 free-base TBPs in air saturated toluene.
The fluorescence quantum yield for H2ArF4TBP was measured relative to
ZnTPP (0.04) with excitation at 420 nm in toluene. The fluorescence quantum
yield for H2TAr2TBP and H2Ar20PrTBP was measured relative to H2Ar2TBP
(0.38) with excitation at 420 nm in toluene. The Si decays were obtained by
single photon counting method.
Absorption
Free-base Amax (Soret, Q-band) nm Fluorescence
Porphyrins (Emax = M-1 cm-1) Amax nm Ofn Tf (ns)

H2ArF4TBP 474, 642 711,788 6.0% 0.4 2.8
E474 = 3.03 x 105
E642= 3.63 x 104

H2TAr2TBP 442, 612 670, 735 39% 1 10.4
E442 = 3.43 x 105
E612= 5.68 x 104

H2Ar20PrTBP 445, 625 674, 743 43% 3 10.6
E445 = 3.22 x 105
E625= 7.23 x 104

Table 3-10. Deactivation rate constants for S1 state of series 3 free-base TBPs in air
saturated toluene. Radiative decay rate constant (kr), calculated as kr = qclk,
and the non-radiative decay rate constant (knr = kic + kisc), calculated as kr = k
knr.

Free-base k = 1/Tf (S-1) k, (s-1) knr (-1) Tf (ns)
Porphyrins

H2ArF4TBP 3.6 x 108 2.1 x 107 3.4 x 108 2.8

H2TAr2TBP 9.6 x 107 3.8 x 107 5.8 x 107 10.4

H2Ar20PrTBP 9.4 x 107 4.1 x 107 5.4 x 107 10.6

The fluorescence QY and S1 lifetime for H2TAr2TBP and H2Ar20PrTBP are

identical to that of H2Ar2TBP. Replacing the tert-butyl substituents on the meso-aryl

substituents of H2Ar2TBP with 4-tert-butylphenyl to give H2TAr2TBP has shown to

reduce solution interactions thus increasing the QY in TPP derivatives but was not


126








expected to significantly increase the QY, but may prevent aggregation in solid state

films.77 The choice of the propyl-substituents in H2Ar20PrTBP was determined from X-

ray crystallography data reported for free-base 5,15-diaryl porphyrins in efforts to

interrupt the dominant offset rr-stacking in the crystal structures.123 The emission

maxima for H2TAr2TBP (670 nm) is identical to H2DPTBP. The PL spectrum of

H2Ar20PrTBP is red shifted ~4 nm and it is unclear if this is from an inductive effect

from the propyl groups or an out of plane distortion of the macrocycle.


1.0
0.8
0.6
0.4
0.2
0.0 -
1.0
0.8
0.6
0.4
0.2
0.0
j< r" I


I.U
0.8
0.6
0.4
0.2
n n


300 400 500 600 700 800 900
Wavelength (nm)

Figure 3-19. Normalized absorption (black) and photoluminescence (red) for series 3
free-base TBPs in air saturated toluene: A) H2ArF4TBP, B) H2TAr2TBP, C)
H2Ar20PrTBP.

127


C


u
El^ A "









The absorption and photoluminescence in deoxygenated toluene for series 3

platinum TBPs is shown in Figure 3-20. The photophysical data for series 3 platinum

TBPs is summarized and reported in Table 3-11. The radiative and non-radiative rates

were calculated and shown in Table 3-12. The Soret and Q-band for Pt-ArF4TBP are

red shifted 8 and 5 nm, respectively, with similar molar absorptivity constants compared

to Pt-TPTBP. The absorption spectrum for Pt-TAr2TBP is nearly identical to Pt-DPTBP

and Pt-Ar2TBP. The Soret band for Pt-Ar20PrTBP has a small red shift of 1 nm relative

to Pt-Ar2TBP. A larger red shift is observed in the Q-band of ~20 nm. The molar

absorptivity constants for Pt-TAr2TBP and Pt-Ar20PrTBP are in line with the Pt-diaryl

TBPs from series 2.

Table 3-11. Photophysical data for series 3 platinum TBPs in deoxygenated toluene.
Quantum yields were measured relative to ZnTPP (0.04) by excitation at 420
nm in toluene. The triplet lifetimes were obtained by transient absorption
spectroscopy.
Absorption
Platinum Amax (Soret, Q-band) Phosphorescence
Porphyrins nm Amax nm Ophos TT-T (ps)
(Emax = M-1 cm-)

Pt-ArF4TBP 438, 617 772 34% 1 20.1
E438 = 2.22 x 105
E617= 1.13 x 105

Pt-TAr2TBP 411,605 769 58% 3 51.7
E411 = 2.15 x 105
E605= 1.67 x 105

Pt-Ar20PrTBP 411,625 786 60% 1 51.8
E411 = 2.06 x 105
E614= 1.47 x 105

The absorption and photoluminescence in deoxygenated toluene for series 3

platinum TBPs is shown in Figure 3-20. The emission maximum for Pt-ArF4TBP is

centered at 772 nm. The T1 lifetime of 20.1 ps for Pt-ArF4TBP is significantly shorter

than that of Pt-TPTBP and Pt-Ar4TBP. This leads to the expected decrease in the


128









phosphorescence QY (0.341) relative to Pt-TPBP and Pt-Ar4TBP. The non-radiative

decay rate constant for Pt-ArF4TBP is doubled compared to Pt-TPTBP. Although no

significant red shift is observed in either the absorption or PL for Pt-ArF4TBP the

increase in knr still suggests non-planar distortions are likely the reason.


1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0


400 600 800


1000


Wavelength (nm)

Figure 3-20. Normalized absorption (black) and photoluminescence (red) for series 3
platinum TBPs in toluene: A) Pt-ArF4TBP, B) Pt-TAr2TBP, C) Pt-Ar20PrTBP.

The emission maximum for Pt-TAr2TBP of 769 nm is blue shifted 1 nm relative to

Pt-Ar2TBP. Similar to H2Ar20PrTBP, the emission maximum for Pt-Ar20PrTBP of 786

nm is red shifted 16 nm relative to Pt-Ar2TBP. The T1 lifetimes for Pt-TAr2TBP and Pt-


129









Ar20PrTBP of 51.7 and 51.8 ps are very close to those of Pt-Ar2TBP (53.0 ps)

measured by transient absorption spectroscopy. Consequently, the QYs should be very

similar as they are directly proportional to the lifetimes but are difficult to accurately

measure. The reported trend by Vinogradov et al of the QY doubling from Pd-TPTBP to

Pd-DPTBP is supported by other literature data. Since the emission from platinum and

palladium porphyrins is largely porphyrin based (rr-rr*) this trend should also hold true

for Pt-Ar2TBP, Pt-TAr2TBP, and Pt-Ar2OPrTBP.124' 125

Table 3-12. Deactivation rate constants for T1 state of series 3 platinum TBPs in
deoxygenated toluene. Radiative decay rate constant (kr), calculated as kr =
CPphosk, and the non-radiative decay rate constant (knr = kic + kisc), calculated
as kr = k- knr.

Platinum k = 1/TT-T (S-1) k (S-1) knr (S-1) TT-T (pS)
Porphyrins

Pt-ArF4TBP 5.0 x 104 1.0 x 104 4.0 x 104 20.1

Pt-TAr2TBP 1.9 x104 1.1 x104 8.1 103 51.7

Pt-Ar20PrTBP 1.9 x 104 1.2 x 104 7.8 x 103 51.8

Series 3- PLED Device Results

PLEDs were fabricated in an identical manner to those in series 2, by spin-coating

the active layer on top of a PEDOT:PSS layer, followed by evaporation of the metal

electrode materials to give the following device structure: glass/ITO/PEDOT:PSS(40

nm)/2% Pt-porphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al.

Electroluminescence from PLEDs fabricated from Pt-ArF4TBP and Pt-TAr2TBP is

centered at -775 nm shown in Figure 3-21A. The PLED fabricated from Pt-Ar20PrTBP

exhibits an electroluminescence maximum at 790 nm, red shifted similar to the PL

emission. No host emission is observed in each device with light emission from the

phosphors turning on at applied voltages (~12 V) identical to series 2 (Figure 3-21C).


130










1.2 le+3

1.0 A le+2 B
I -CI le+1
-0 0.8
N "" le+0
S0.6 <
E E le-1
0 0.4 \
z le-2
0.2 le-3

0.0 l1 e-4
600 700 800 900 1000 0 5 10 15 20 25
Wavelength (nm) Voltage (V)
le+4 .1.8
c 1.6 D ****
le+3 1.4
C0J 1.2
E le+2 *
U LU 1 .0
le+0 0.8
-1e+1 LU
Q-/ 0.6

S0.2
l e 1 --- 0.0 .. ... .. .
510 15 20 25 le-1 le+ le+1 le+2
Voltage (V) J (mA/cm2)


Figure 3-21. PLED device results for series 3 platinum TBPs with the following device
structure: glass/ITO/PEDOT:PSS(40 nm)/2% Pt-porphyrin:PVK:PBD(7:3)
(110 nm)/LiF(1 nm)/Ca(10 nm)/Al. Pt-ArF4TBP (black), Pt-TAr2TBP (red), and
Pt-Ar20PrTBP (green). A) EL spectra for PLEDs, B) J-V plot, C) R-V plot, D)
External quantum efficiency.

The PLEDs exhibit maximum radiant emittance of approximately 1.6-1.8 mW/cm2

(Figure 3-21C). The maximum EQEs for the series range from 1.2-1.7%. The PLED

fabricated from Pt-ArF4TBP gave the highest EQE (1.7%) slightly higher than Pt-TPTBP

(1.5%). Pt-TAr2TBP and Pt-Ar20PrTBP both have significantly higher phosphorescence

QYs compared to Pt-TPTBP and Pt-ArF4TBP but no significant gain is observed in

device efficiency. The maximum EQE for Pt-TAr2TBP and Pt-Ar20PrTBP are 1.5 and

1.2% respectively. Comparison of series 2 and 3 PLEDS from platinum TBPs with

similar solution QYs and lifetimes give the following trends with respect to the maximum


131









EQE data: Pt-ArF4TBP > Pt-TPTBP > Pt-Ar4TBP and Pt-TAr2TBP > Pt-Ar2TBP > Pt-

Ar20PrTBP. The two major conclusions can be drawn from the observed trend. The frist

is that despite the increased solution QYs of the platinum diaryl-TBPs large increases

are not observed in device efficiency. This is likely due to bimolecular interactions that

lead to self quenching pathways. The second, is that the addition of bulky substituents

in the meso-aryl positions lead to small to moderate increases in device efficiency

demonstrating that the substituents have little affect on the porphyrin:host polymer

morphology.

Series 3- OLED Device Results

Multilayer OLEDs were fabricated by thermal vapor deposition of Pt-TAr2TBP and

Pt-Ar20PrTBP to give the following device structure: glass/ITO/NPB(40 nm)/Alq3:4% Pt-

TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/AI. Thermal vapor deposition was not attempted

due to the high molecular weight of Pt-ArF4TBP. Electroluminescence from the OLEDs

for Pt-TAr2TBP and Pt-Ar20PrTBP is centered at 775 and 790 nm respectively and is

shown in Figure 3-22A. Turn on voltages of ~2 V and maximum radiant emittance of 1

mW/cm2 obtained at ~12V are in line with the data from series 2 OLEDs (Figure 3-22B).

The current densities from the J-V plot for both devices are similar and expected due to

the identical device structure (Figure 3-22B).

The EQE data shown in Figure 3-22D for both devices follows a different trend than the

PLED EQE data. Pt-TAr2TBP exhibits a lower maximum EQE (3.2%) than Pt-

Ar20PrTBP (6.9%). While Pt-TAr2TBP and Pt-Ar20PrTBP have identical solution

photophysics as Pt-Ar2TBP the overall OLED EQEs range from 3.2-7.8%. The

variations in performance are not well understood and likely originate from some

physical property of the porphyrin:Alq3 films. The observed trend demonstrates that the


132










additional substituents have a negative impact on the device efficiency. In the case of

Pt-TAr2TBP the maximum EQE is two times lower than that of the Pt-Ar2TBP based

OLED. This suggests that the additional substituents in Pt-TAr2TBP and Pt-Ar20PrTBP

do not enhance mixing with the host (Alq3) or prevent bimolecular quenching pathways.

1.2 1e+4 1 le+1
1A 1e+3 B 1e+0
S1e+2 le-1
-0 0.8 I 1 le+1 le-2 E
U, E
E 0.6
E E le-1 [ I e1-4
lle-E
S0.4 l e-2 l1e-5
z
1e-3 0 o 1e-6
0.2 o ,
le-4 1 e-7
0.0 1 e-5 e-8
600 700 800 900 1000 0 2 4 6 8 10 12 14 16
Wavelength (nm) Voltage (V)
60 ................................................. 10

50 -C D

40 .. *...
0 6 *
E 30 *

20 %**4

10

0 0
1e-4 1e-3 1e-2 le-1 le+0 le+1 le+2 le+3 1e-4 le-3 1e-2 le-1 le+0 le+1 le+2 le+3

J (mA/cm2) J (mA/cm2)

Figure 3-22. OLED device results for series 3 platinum TBPs. Pt-TAr2TBP (black), Pt-
Ar20PrTBP (red) with device structure: glass/ITO/NPB(40 nm)/Alq3:4% Pt-
TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/AI. A) EL spectra for PLEDs, B) J-V
plot (closed circles) and R-V plot (open circles), C) Power efficiency, D)
External quantum efficiency.

Conclusion

Electroluminescent OLEDs and PLEDs have been prepared by thermal vapor

deposition with small molecule hosts and solution blending with polymers respectively


133









for each series of rr-extended platinum porphyrins. The device wavelengths of the near-

IR electroluminescence range from 770 to 1005 nm based on the rr-extended platinum

porphyrin system used. OLEDs have been prepared with record efficiencies of 9.2%

and 3.8% at 770 and 898 nm respectively. In general, as the wavelength increases a

decrease in overall device efficiency is observed for both PLEDs and OLEDs in accord

with the energy gap law. Unexpectedly, devices fabricated using phosphors with

significantly larger PL efficiency did not directly translate into higher device efficiency.

Large ranges in device efficiency for phosphors with similar photophysical properties

suggest a physical property of the platinum porphyrin in the solid state or a

porphyrin:host morphology plays a major role in device efficiency.

Experimental

Optical Characterization. Absorption spectra for all free-base and platinum n-

extended porphyrins were measured using a PerkinElmer Lambda 25 UV-vis

spectrometer. The PL spectra were obtained by excitation at the Soret band absorption

maximum for each compound. The spectra were recorded with an ISA Spex Triax 180

spectrograph coupled to a Spectrum-1 liquid nitrogen silicon charge coupled device

detector. This spectrometer has a relatively flat spectral response to 900 nm, although

there is some loss in efficiency due to the grating, which is blazed in the visible region.

The PL for Pt-Ar4TAP was measured separately on a PTI fluorimeter equipped with

InGaAs near-IR detector and a Spex Fluorolog II equipped with InGaAs near-IR

detector. The solution fluorescence and phosphorescence quantum yields were

calculated relative to ZnTPP in toluene (0.04) unless otherwise noted according to a

previously described method.117 126 The sample and actinometer solutions had matched

optical density at a shared excitation wavelength. The emission spectra were corrected


134









for the spectrometer response prior to being used to compute the quantum yield. Time-

resolved transient absorption spectra for rr-extended platinum porphyrins in toluene

were collected by using previously described laser systems for the visible and near-IR

regions.127

Device Fabrication and Characterization. PLEDs were fabricated by Ken

Graham from the Reynolds group at the University of Florida using the following

method. PLEDs were fabricated on pre-patterned indium tin oxide (ITO) coated glass

substrates with a sheet resistance of ~20 Q/. The ITO substrates were cleaned

sequentially with a sodium dodecyl sulfate solution, acetone, and isopropyl alcohol

followed by exposure to an oxygen plasma. A layer of PEDOT:PSS (Baytron P VP

A14083) was spin-coated on the ITO immediately following oxygen plasma exposure

and then annealed at 1200C under vacuum for 2 h. The active layer solutions consisting

of varying weight percentages of rr-extended platinum porphyrins in PVK:PBD were

prepared and spin-coated from chlorobenzene in an MBraun glovebox with <0.1 ppm

oxygen and water. The cathode consisting of LiF (1 nm), Ca (10 nm), and Al (80 nm)

was deposited in a thermal evaporator under a vacuum of 10-6 Torr. Radiant emittance

(R)-voltage (V) measurements were carried out using a calibrated UDT Instruments

silicon detector. Current density (J)-voltage (V) measurements were carried out using a

Keithley 2400 sourcemeter. The electroluminescence (EL) spectra were collected using

the ISA SPEX Triax 180 spectrograph or a Spex Fluorolog II equipped with InGaAs

near-IR detector with the devices driven using the Keithley sourcemeter. Each 2.5 x 2.5

cm substrate features eight independently addressable pixels with area 0.07 cm2, and

the results presented herein represent measurements averaged over three pixels.


135









The OLEDs were fabricated by Yixing Yang in Dr. Xue's group Department of

Materials Science at the University of Florida. The OLEDs were fabricated on glass

substrates commercially coated with an ITO anode with a sheet resistance of ~20 Q/.

The substrates were cleaned in ultrasonic baths of deionized water, acetone, and

isopropyl alcohol consecutively for 15 min each and then exposed to an ultraviolet

ozone environment for 15 min immediately before loading into a high vacuum chamber

(base pressure ~10-7 Torr). All the layers including the cathode, were deposited using

vacuum thermal evaporation following procedures published previously.128 The

thicknesses of the HTL and EML were 40 and 20 nm, respectively, whereas the ETL

layer thickness was 100 nm, optimized to achieve the highest device efficiencies. A 1

nm layer of LiF followed by a 100 nm Al layer was then deposited as the cathode.

Radiant emittance (R)-current density (J)-voltage (V) characteristics were measured

under ambient conditions using an Alilent 4155C semiconductor parameter analyzer

and a calibrated Newport silicon detector. The EL spectra were collected as described

above, with the device driven at a constant current. The radiant emittance for both

OLEDs and PLEDs was calibrated assuming Lambertian emission, and the EQE and

electrical-to-optical power efficiency values were derived on the basis of the

recommended methods.129 Each 2.5 x 2.5 cm substrate features four independently

addressable pixels with area 4mm2, and the results presented herein represent

measurements averaged over at least eight pixels.


136









CHAPTER 4
CONCLUSIONS

The previous chapters detail the investigation of rr-extended platinum porphyrins

as near-IR phosphors for use in near-IR LED applications. Reported are the synthesis,

characterization and photophysical properties with the PLED and OLED device data for

three novel series of rr-extended platinum porphyrins. The photophysical properties of

porphyrins make them excellent candidates for use in LED applications due to their

narrow emission. The use of phosphors over fluorophores has been shown to give

theoretical device efficiencies of a 100%. Therefore high efficiency devices can only be

achieved with materials that posses phosphorescence quantum yields approaching

unity. The insertion of a transition metal such as palladium or platinum forming a

metalloporphyrin induces intersystem crossing to give phosphors with high

phosphorescence quantum yields that are ideal candidates for LED applications.

The photophysical properties of porphyrins with fused-benzo rings have long been

of interest with the platinum complexes of this class of porphyrins almost completely

absent from the literature. Herein is the first full report of the photophysical properties for

rr-extended platinum porphyrins. The high PL efficiencies of the platinum complexes for

TBP, TNP and TAP systems make them ideal choices for near-IR phosphors. OLEDs

and PLEDs have been fabricated in order to demonstrate the application of these

materials in near-IR LEDs.

Conclusions and Future work. The synthetic work and photophysical

characterization for each series with the reported PLED and OLED device data has

significantly advanced the field of near-IR LEDs based upon the use of rr-extended

platinum porphyrins a near-IR phosphors. The advancements from series 1 include


137









devices with EL reaching further into the near-IR (900 and 1000 nm) while also

achieving new device efficiency records for each new wavelength region. The

preparation and characterization of series 2 platinum TBPs produced the brightest

platinum TBP ever reported. This record quantum yield expands farther than platinum

TBPs and is the highest known for this wavelength region of any reported material. The

structures designed for series 3 platinum TBPs attempted to prevent quenching

mechanisms in the device from porphyrin-porphyrin interactions through chemical

modification of the porphyrin macrocycle. This series represents some of the most

complex TBPs reported to date while also furthering the understanding of substituent

effects on the photophysical properties on the TBP macrocycle.

While this body of work has answered many questions concerning the use of rr-

extended platinum porphyrins for near-IR LED applications it has also raised many

more. The large increase in the solution quantum yield observed in series 2 did not

directly translate into significantly higher device EQEs. This result along with the device

data from series 3 platinum TBPs suggest that the translation of solution photophysical

properties to the solid state for these novel phosphors is not well understood. Future

work should be directed towards gaining an understanding of how these materials

behave in the solid state. A clear understanding of the solid state photophysical

properties is necessary to completely achieve optimized device efficiencies. It would

also be advantageous to thoroughly examine the photophysical properties as a function

of concentration in a select variety of host materials. The device data for series 2 and 3

shows significant variations for materials with identical solution photophysical

properties. This strongly suggest a physical property or unique morphology exist


138









between the phosphor and host material ultimately contributing to an increase or

decrease in device efficiency. The investigation and answers to these questions may

provide the data necessary to utilize the record quantum yield of near-IR phosphors like

Pt-Ar2TBP achieving much higher device efficiencies.


139










APPENDIX A
FIGURES


0 I J. I I
0 20 40 60 0 20 40 60

Time (ns)

Figure A-1. Fluorescence lifetimes for Series 1 free-base rr-extended porphyrins in air
saturated toluene: A) H2TPTBP, B) H2TPTNP, C) H2Ar4TNP(OMe)8, D)
H2Ar4TAP.


140
























400 500 600 700 800


Figure A-2. T1-Tn absorption data for series 1 rr-extended platinum porphyrins in
deoxygenated toluene: A) Pt-TPTBP, B) Pt-TPTNP, C) Pt-Ar4TNP(OMe)8, D)
Pt-Ar4TAP.


141


400 500 600 700 800












30000

25000

20000

15000

10000

Cl) 5000

00
30000 C D

25000

20000

15000

10000

5000


0 10 20 30 40 50 60 0 10 20 30 40 50 60

Time (ns)


Figure A-3. Fluorescence lifetimes for Series 2 free-base rr-extended TBPs in air
saturated toluene: A) H2TPTBP, B) H2DPTBP, C) H2Ar4TBP, D) H2Ar2TBP.


142












0.2 .. 0.10
0.1 : 0.05
0.0 0.00
-0.1 -0.05
-0.2 -0.10
-0.3 -0.15
-0.4 -0.20
-0.5 A -0.25 B
(C -0.6 .......'.'...................... -0.30
400 500 600 700 800 400 500 600 700 800
,--
0
U)
0.2 0.08

< 0.1 0.06

0.0 0.04

-0.1 0.02

-0.2 0.00


-0.4 -0.02
-0 .4 -0 .04 .
400 500 600 700 800 400 500 600 700 800


Wavelength (nm)


Figure A-4. T1-Tn absorption data for series 2 -rr-extended platinum TBPs in
deoxygenated toluene: A) Pt-TPTBP, B) Pt-Ar4TBP, C) Pt-DPTBP, D) Pt-
Ar2TBP.


143











35000

30000 A

25000

20000

15000

10000


U 35000 .
35000 .---- r---- .------.------.------.----.

30000 B (

25000

20000

15000

10000

5000

0 .. .
0 20 40 60 0 20 40 60


Time (ns)


Figure A-5. Fluorescence lifetimes for Series 3 free-base rr-extended TBPs in air
saturated toluene: A) H2ArF4TBP, B) H2TAr2TBP, C) H2Ar20PrTBP.


144


























0.0 L-
300


400 500 600 700 800


900


Wavelength (nm)


Figure A-6. Normalized absorption and PL of H2TPTBP (black and red) and H2ArF4TBP
(green and blue) in air saturated toluene.


145












0.05
0.00
-0.05
-0.10
-0.15
()
0 -0.20

-0.25 A
Q -0.30
0 400 500 600 700 800
-Q
0.05







0.00 -0.10

B '-o15 C
-0.05 B C

400 500 600 700 800 400 500 600 700 800


Wavelength (nm)


Figure A-7. T1-Tn absorption data for series 3 -rr-extended platinum TBPs in
deoxygenated toluene: A) Pt-ArF4TBP, B) Pt-TAr2TBP, C) Pt-Ar20PrTBP.


146

































Eem (0,0) in eV


Figure A-8. Plot of the natural
emission maximum


log of the non-radiative decay constant (knr) and the
in eV (Eem) for series 1 rr-extended plantium porphyrins.


147


SO












APPENDIX B
NMR SPECTRA


Figure B-1. H NMR (300 MHz, CDCI3) spectrum of 6.


AJL


Figure B-2. H NMR (300 MHz, CDCI3) spectrum of 17b.


148


11111111
100 9.. 90 8_5 80 75 ,0 .5 bO 55 50 4.5 10 76 ~ 25 20 15 1.0 06
cnetnral9nmlppml


6.5 50 66 50 4.5 4.0 55
cnamral snm IPPml


_. Lap
'.a L^ I




















A- __ LL I ii i" Ir*Ji__ -
Chemkl snift (ppml

Figure B-3. 1H NMR (300 MHz, CDCG3) spectrum of 18b.


'-rh


-- h


C-hmFgal N ( M ppeum

Figure B-4. 1H NMR (300 MHz, pyridine-d5) spectrum of 39b.


149


kkL -- --L

















Figure B-5. 1H NMR (500 MHz, pyridine-d5) spectrum of 39c.


NMR (500 MHz, pyridine-d5) spectrum of 40b.


Figure B-6. 1H


150


I


_J~ I
















Figure B-7. 1H NMR (500 MHz, pyridine-ds) spectrum of 42.


Figure B-8. 1H NMR (500 MHz, pyridine-ds) spectrum of 45c.


151


L.-


















i i /


Figure B-9. 1H NMR (500 MHz, pyridine-ds) spectrum of 45d.


I I I I


Figure B-10. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-39b.


152


^t*^^ A I


-J JA0L L^ Jn





















--IA


Figure B-11. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-39c.


Figure B-12. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-40a.









153


C 1


























Figure B-13. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-40b.




















Figure B-14. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-42.


154




























Figure B-15. 1H NMR (500 MHz, pyridine-ds) spectrum of Pt-45b.


Figure B-16.H NMR (500 MHz, pyridine-d) spectrum of Pt-45c.
Figure B-16. lH NMR (500 MHz, pyridine-ds) spectrum of Pt-45c.


155
























Figure B-17. H NMR (500 MHz, pyridine-ds) spectrum of Pt-45d.
Figure B-17. lH NMR (500 MHz, pyridine-ds) spectrum of Pt-45d.


156









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phthalocyanine: A density functional theory study," J. Chem. Phys. 114, 10757-
10767 (2001).

123. A. D. Bond, N. Feeder, J. E. Redmen, S. J. Teat and J. K. M. Sanders,
"Molecular Conformations and Intermolecular Interactions in the Crystal
Structures of Free-Base 5,15-Diarylporphyrins," Crystal Growth & Design 2, 27-
29 (2002).

124. K. M. Smith, Porphyrins and Metalloporphyrins. (Elsevier Press, New York,
1975).

125. A. Antipas and M. Gouterman, "Porphyrins. 44. Electronic states of cobalt, nickel,
rhodium, and palladium complexes," J. Am. Chem. Soc. 105, 4896-48901 (1983).

126. G. A. Crosby and J. N. Demas, "The Measurement of Photoluminescence
Quantum Yields. A Review," J. Phys. Chem. 75, 991-1024 (1971).

127. Y. Wang and K. Schanze, "Photochemical probes of intramolecular electron and
energy transfer," Chemical Physics 176, 305-319 (1993).

128. Y. Zheng, S.-H. Eom, N. Chopra, J. Lee, F. So and J. Xue, "Efficient Deep-Blue
Phosphoescent Organic Light-Emitting Device with Improved Electron and
Exciton Confinement," J. Appl. Phys. Lett. 92, 223-301 (2008).

129. S. R. Forrest, D. D. Bradley and M. E. Thompson, "Measuring the Efficiency of
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BIOGRAPHICAL SKETCH

Jonathan R. Sommer was born in Cheboygan, Michigan, and grew up in Orange

Park, Florida, a suburb of Jacksonville. He spent the majority of his childhood outside

fishing and playing sports such as football and basketball. Jonathan continued playing

football while at Orange Park High School growing mentally and physically from the

coaching and mentorship of Coach Bill Shields and Roy Clayton. His college career

started at Jacksonville University playing football for the Dolphins and studying

chemistry. However, his deep affection for the triple-option, which developed during his

prep career, led him to transfer to Georgia Southern University to play football under

Head Coach Paul Johnson. Here he continued working towards his Bachelor of Science

in chemistry. He took a strong interest in both organic chemistry and quantum

mechanics from working with his undergraduate research advisors Dr. Kurt Weigel and

Dr. James LoBue. He began his graduate studies at the University of Florida under the

guidance of Prof. Kirk S. Schanze which provided the opportunity to synthesis advanced

materials and study their photophysical properties for materials science applications

while pursuing a doctoral degree in organic chemistry.


168





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1 EXTENDED PLAT INUM PORPHYRINS FOR APPLICATION IN HIGH EFFICIENCY NEARIR LIGHT EMITTING DIODES By JONATHAN ROBERT SOMMER A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2010

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2 2010 Jonathan Robert Sommer

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3 To my parents and to my friends for t heir unwavering love and support

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4 ACKNOWLEDGMENTS I would like to express my gratitude to my advisor, Prof essor Kirk S. Schanze, whose support and direction have helped me develop and enabled me to complete my studies. His overall knowledge of science not just chemistry is extremely impr essive. The mentorship I received from him has guided me through my many challenges as a graduate student and for that I will always remain appreciative and thankful for the opportunity to have worked with him I would especially like to thank, Dr. William Dolbier and Dr. Ken neth Wagener for their time in the class room and also as members of my committee Their knowledge, advice, and support have been a valuable and cherished resource during my graduate career This work would not have been possible with out the hard work of our many collaborators with whom I have interacted: Dr. Ion G hiviriga for his expertise in NMR and help with characterization of the porphyrins prepared in Chapter 2; Dr. John Reynolds and Dr. Jiangeng Xue for their collaboration and expertise in both chemistry and light emitting diodes; Ken Graham for the fabrication and characterization of PLEDs and our stimulating discussions on aggregation and device efficiency; Yixing Yang for the fabrication a nd characterization of OLEDs; Dr. Richard Farley and Abby Shelton for their help with the photophysical characterization of the platinum porphyrins synthesized in Chapter 2. I would like to thank all of the present and past members of the Schanze research group. I have made some great friends along the way and enjoyed watch ing them grow into talented scientist s

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 7 LIST OF FIGURES .......................................................................................................... 8 LIST OF ABBREVIATIONS ........................................................................................... 12 ABSTRACT ................................................................................................................... 13 CHAPT ER 1 INTRODUCTION TO PORPHYRINS ...................................................................... 15 History and Discovery of Porphyrins The Pigments of Life .................................... 15 Structure and Nomenclature of Porphyrins ....................................................... 16 History of Porphyrin Synthesis ......................................................................... 18 Synthesis of meso Substituted Porphyrins ................................................ 19 Extended Porphyrins .......................................................... 21 Introduction to Photophysics ................................................................................... 28 Absorption of Light ........................................................................................... 28 Nature of the Excited State ............................................................................... 31 Relaxation of the Excited States ....................................................................... 32 Photophysics of Porphyrins .................................................................................... 33 Absorption of Metalloporphyrins ....................................................................... 33 Introduction to Porphyrin Emission ................................................................... 36 Emission from Metalloporphyrins ..................................................................... 36 Near IR Light Emitting Diodes: Stateof the Art ................................................ 38 Extended Platinum Porphyrins as Near IR Phosphors ................................. 41 Objective of Present Study ............................................................................... 44 2 SYNTHESIS OF EXTENDED PLATINUM PORPHYRI NS .................................. 46 Introduction ............................................................................................................. 46 Synthesis of Aromatic Aldehydes for Extended Porphyrins .......................... 51 Synthesis of Pyrroles for Extended Porphyrins ............................................. 52 Synthesis of Symmetrical Extended Porphyrins .................................................. 55 Deprotec tion of Pyrrole Esters ................................................................... 55 Synthesis of Tetraaryltetrabenzoporphyrins ............................................... 56 Synthesis of Tetraaryltetranaphthoporphyrins ............................................ 57 Synthesis of Tetraryltetraanthroporphyrins ................................................ 58 Synthesis of 5,15Diaryltetrabenzoporphyrins ............................................ 59 Synthesis of Extended Platinum Porphyrins ................................................. 60

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6 Conclusions ...................................................................................................... 63 Experimental .................................................................................................... 63 3 PHOTOPHYSICS AND DEVICE RESULTS ........................................................... 95 Introduction ............................................................................................................. 95 Electroluminescence Mechanisms ................................................................... 96 Organic Light Emitting Diodes .......................................................................... 98 Polymer Light Emitting Diodes ....................................................................... 101 R esults and Discussion ............................................................................ 102 Series 1Photophysical Properties .......................................................... 102 Series 1PLED Device Results ............................................................... 110 Series 1OLED Device Results ............................................................... 113 Series 2Photophysical Properties .......................................................... 114 Series 2PLED Devic e Results ............................................................... 121 Series 2OLED Device Results ............................................................... 122 Series 3Photophysical Properties .......................................................... 124 Series 3PLED Device Results ............................................................... 130 Series 3OLED Device Results ............................................................... 132 Conclusion ............................................................................................................ 133 Experimental ......................................................................................................... 134 4 CONCLUSIONS ................................................................................................... 137 APPENDIX A FIGURES .............................................................................................................. 140 B NMR SPECTRA .................................................................................................... 148 LIST OF REFERENCES ............................................................................................. 157 BIOGRAPHICAL SKETCH .......................................................................................... 168

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7 LIST OF TABLES Table page 1 1 Recent literature reports of near IR LED devices ............................................... 39 3 1 Photophysical properties of Series 1 freebase extended porphyrins ........... 104 3 2 Deactivation rate constants for S1 state of series 1 freebase extended porphyrins ........................................................................................................ 105 3 3 Photophysical data for series 1 extended platinum porphyrins ..................... 107 3 4 Deactivation rate constants for T1 state of series 1 extended platinum porphyrins ........................................................................................................ 107 3 5 Photophysical properties of Series 2 freebase TBPs ...................................... 116 3 6 Deactivation rate constants for S1 state of series 2 freebase TBPs ................ 117 3 7 Photophysical data for series 2 platinum TBPs ................................................ 117 3 8 Deactivation rate constants for T1 state of series 2 platinum TBPs .................. 121 3 9 Photophysical properties of Series 3 freebase TBPs ...................................... 126 3 10 Deactivation rate constants for S1 state of series 3 freebase TBPs ................ 126 3 11 Photophysical data for series 3 platinum TBPs ................................................ 128 3 12 Deactivation rate constants for T1 state of series 3 platinum TBPs .................. 130

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8 LIST OF FIGURES Figure page 1 1 Chlorophyll and heme are two naturally occurring porphyrins ............................ 15 1 2 Porphyrin nomenclature developed by Hans Fischer. ........................................ 17 1 3 The numerical IUPAC nomenclature for porphyrins ........................................... 17 1 4 Outline of the most common substitution patterns found around the porphyrin macrocycle ......................................................................................................... 18 1 5 Outline of the synthetic conditions for the preparation of meso aryl substituted porphyrins ........................................................................................ 20 1 6 General structures for phthalocyanine and meso extended porphyrins .......................................................................................................... 22 1 7 Initial synthetic strategy developed by Linstead and Tuey for the preparation of TBP ................................................................................................................ 23 1 8 Synthetic scheme reported by Kunkely and Volger in 1978 for the preparation of ZnTBP ............................................................................................................ 23 1 9 Outline of synthetic strategy to prepare H2TPTBP .............................................. 24 1 10 The synthesis reported by Ono et al for the preparation of H2Ar4TBP ................ 25 1 11 Outline of the oxidative aromatization strategy for the preparation H2Ar4TBPs .. 26 1 12 Synthetic strategy for H2Ar4TNP using the dihydroisoindole method ................. 27 1 13 Potential energy curves for electronic transitions ............................................... 30 1 14 Jablonski diagram showing the possible transitions for a singlet excited state after absorpt ion of a photon. ............................................................................... 32 1 15 Examples of metalloporphyrin absorption spectra .............................................. 34 1 16 Jablonski diagram showing the decay schemes for singlet and triplet relaxation after absorption of a photon. .............................................................. 35 1 17 Examples of metalloporphyrin emission ............................................................. 37 1 18 Lanthanide based near IR emission from lanthanide monoporphyrinate complexes towards near IR LED applications .................................................... 40 1 19 Near IR OLED device data for Pt TPTBP doped in to Alq3................................. 41

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9 1 20 Current literature reports for freebase and metalloTBPs. ................................. 42 1 21 Current literature reports for freebase and metalloTNPs. ................................. 43 1 22 Current literature reports for freebase and metalloTAPs. ................................. 44 2 1 General structures for meso extended porphyrins. ................... 46 2 2 Target free base and platinum porphyrins towards new near IR phosphors. ..... 49 2 3 Synthetic scheme for aromatic aldehydes towards meso aryl substituted extended porphyrins ........................................................................................... 51 2 4 Synthetic scheme for b enzopyrroles towards TBPs ........................................... 52 2 5 Synthetic scheme for naphthopyrroles towards TNPs ........................................ 53 2 6 Synthetic scheme for anthropyrroles towards TAPs ........................................... 54 2 7 Synthetic scheme for the deprotection of pyrrole esters ..................................... 56 2 8 Synthetic scheme for H2Ar4TBPs ....................................................................... 56 2 9 Synthetic scheme for H2Ar4TNP s ....................................................................... 57 2 10 Synthetic scheme for H2Ar4TAP ......................................................................... 58 2 11 Synthetic scheme for H2Ar2TBPs ....................................................................... 59 2 12 Platinum metallation reaction for Pt TPTNP followed by UV vis spectroscopy ... 61 2 13 Synthetic s cheme for extended platinum porphyrins ...................................... 62 3 1 Single layer device structure for the first reported OLED and PLED ................. 95 3 2 Devi ce structure of a multilayer light emitting diode with a diagram of electroluminescence mechanism. ....................................................................... 98 3 3 Examples of small molecule hole transport materials ........................................ 99 3 4 Examples of small molecule host material s ........................................................ 99 3 5 Examples of small molecule electron transport materials ................................ 100 3 6 Examples of polymer host materials for polymer light emitting diodes ............ 101 3 7 Structures for series 1 extended freebase and platinum porphyrins. ........... 103

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10 3 8 Normalized absorption and photoluminescence of Series 1 freebase extended porphyrins ......................................................................................... 106 3 9 Normalized absorption and photoluminescence for series 1 extended platinum porphyrins ......................................................................................... 109 3 10 PLED device results for series 1 extended platinum porphyrins ................... 111 3 11 Hybrid PLED device for Pt Ar4TAP .................................................................. 112 3 12 OLED device results for series 1 extended platinum porphyrins ................... 114 3 13 Structu res of freebase and platinum complexes for series 2 TBPs. ................ 115 3 14 Normalized absorption and photoluminescence of series 2 freebase TBPs ... 118 3 15 Normalized absorption and photoluminescence for series 2 platinum TBPs ... 119 3 16 PLED device results for series 2 platinum TBPs .............................................. 122 3 17 OLED device results for series 2 plat inum TBPs .............................................. 123 3 18 Structures of freebase and platinum complexes for series 3 TBPs. ................ 125 3 19 Normalized absorption and photoluminescence for series 3 freebase TBPs 127 3 20 Normalized absorption and photoluminescence for series 3 platinum TBPs .... 129 3 21 PLED device results for series 3 platinum TBPs ............................................. 131 3 22 OLED device results for series 3 platinum TBPs .............................................. 133 A 1 Fluorescence lifetimes for Series 1 freebase extended porphyrins ............. 140 A 2 T1Tn absorption d ata for series 1 extended platinum porphyrins ................. 141 A 3 Fluorescence lifetimes for Series 2 freeb ase extended TBPs .................... 142 A 4 T1Tn absorption data for series 2 extended platinum TBPs ......................... 143 A 5 Fluorescence lifetimes for Series 3 freebase extended TBPs ..................... 144 A 6 Normalized absorption and PL of H2TPTBP and H2ArF4TBP ........................... 145 A 7 T1Tn absorption data for series 3 extended platinum TBPs ........................ 146 A 8 Plot of the natural log of the nonradiative decay constant and the emis sion maximum in eV for series 1 extended plantium porphyrins. .......................... 147

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11 B 1 1H NMR (300 MHz, CDCl3) spectrum of 6 ....................................................... 148 B 2 1H NMR (300 MHz, CDCl3) spectrum of 17b ................................................... 148 B 3 1H NMR (300 MHz, CDCl3) spectrum of 18b ................................................... 149 B 4 1H NMR (300 MHz, pyridine d5) spectrum of 39b ............................................ 149 B 5 1H NMR (500 MHz, pyridine d5) spectrum of 39c ............................................ 150 B 6 1H NMR (500 MHz, pyridined5) spectrum of 40b ............................................ 150 B 7 1H NMR (500 MHz, pyridine d5) spectrum of 42 .............................................. 151 B 8 1H NMR (500 MHz, pyridined5) spectrum of 45c ............................................ 151 B 9 1H NMR (500 MHz, pyridine d5) spectrum of 45d ............................................ 152 B 10 1H NMR (500 MHz, pyridined5) spectrum of Pt 39b ....................................... 152 B 11 1H NMR (500 MHz, pyridine d5) spectrum of Pt 39c. ....................................... 153 B 12 1H NMR (500 MHz, pyridine d5) spectrum of Pt 40a. ....................................... 153 B 13 1H NMR (500 MHz, pyridine d5) spectrum of Pt 40b ....................................... 154 B 14 1H NMR (500 MHz, pyridine d5) spectrum of Pt 42. ......................................... 154 B 15 1H NMR (500 MHz, pyridine d5) spectrum of Pt 45b ....................................... 155 B 16 1H NMR (500 MHz, pyridine d5) spectrum of Pt 45c. ....................................... 155 B 17 1H NMR (500 MHz, pyridine d5) spectrum of Pt 45d ....................................... 156

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12 LI ST OF ABBREVIATIONS DB U 1,8 Diazabicyclo[5.4.0]undec 7 ene DCM Dichloromethane DDQ 2,3 dichloro5,6 dicyanobenzoquinone EtOH Ethanol m CP BA 3 Chloroperoxybenzoic acid MeOH Methanol ITO Indium tin oxide tBuOK Potassium tert butoxide OEP Octaethylporphyrin PBD 2 (4 biphenylyl) 5 phenyl 1,3,4 oxadiazole Pc Phthalocyanine PEDOT Poly(3,4ethylenedioxythiophene) PhCN Benzonitrile PSS Poly(styrenesulfonate) PVK P oly(9 vinylcarbazole) TAP Tetraanthroporphyrin TBP Tetrabenzoporphyrin TFA Trifluoroacetic acid THF Tetrahydrofuran TN P Tetranaphthoporphyrin TPP Tetraphenylporphyrin TsCl m Toluenesulfonyl Chloride TsOH p Toluenesulfonic acid ZnTBP Zinc(II) Tetrabenzoporphyrin

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13 Abstract of Dissertation Presented to the Graduate School of the University of Florida in Parti al Fulfillment of the Requirements for the Degree of Doctor of Philosophy EXTENDED PLATINUM PORP HYRINS FOR APPLICATION IN HIGH EFFICIENCY NEARIR LIGHT EMITTING DIODES By Jonathan Robert Sommer August of 2010 Chair: Kirk S. Schanze Major: Chemistry My research presents the synthesis and photophysical characterization of extended platinum porphyrins. These novel near IR phosphors have emission ranging f rom 770 to 1000 n m with the highest photoluminescence efficiencies ever reported Organic l ight emitting diodes (OLEDs) tha t feature electroluminescence solely in the near IR have been fabricated from these materials by two methods: thermal vapor deposition of small molecules (OLEDs) and solution processing with polymers to form thin films (PLEDs) The synthesis of the platin um complexes for extended porphyrins has been retar d ed due to the difficulty and low yield by current methods. Developed herein is a novel metallation procedure to obtain for the first time platinum complexes for extended porphyrins in high yield. This breakthrough has enabled the realization of these materials which would otherwise not be possible. The goal of the first series of extended platinum porphyrins was to extend the conjugation of the porphyrin macrocycle so emission wavelengths could be obtained further i n the near IR. The addition of fusedbenzene rings to the carbons of the

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14 pyrrole residues effectively extends the conjugation of the porphyrin macrocycle. The platinum tetrabenzoporphyrins in the second series of target compounds were designed in efforts to increas e the solution quantum yield. This was achieved by decreasing the nonradiative decay rate through increasing the planarity of the tetrab enzoporphyrin macrocycle by reducing the number of meso aryl substituents. This resulted in the desired high er quantum yield. The third series of platinum tetrabenzoporphyrins examines the effects of a variety of substituents on the photophysical properties and device efficiency. The materials were designed in efforts to create a dye encapsulation effect to prev ent self quenching mechanism caused by aggregation. The most important conclusions from this study are as follows: (i) the use of platinum acetate as the metallation reagent readily affords the desired platinum complexes; (ii) the lifetimes and quantum yi elds for series 1 extended platinum porphyrins follows the energy gap law, were the lifetime and quantum yield decrease with longer emission wavelengths; (iii) increasing the macrocycle planarity decreases the nonradiative decay rate, thus increasing the quantum yield and lifetime; (iv) self quenching mechanisms from aggregation of the extended platinum porphyrins in the host material of OLEDs and PLEDs remains a problem seriously limiting the device efficiency despite the high photoluminescence efficiency of the phosph ors

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15 CHAPTER 1 INTRODUCTION TO PORPHYRINS History and Discovery of Porphyrins The Pigments of Life T he vast majority of complex animal and plant life that exists on our planet today results from a class of compounds called porphyrins Photosynthesis and respiration are at the heart of what makes life possible. During the Archean eon life on earth was dominated by bacteria and archaea with the atmosphere void of free oxygen. The evolution of oxygenic photosynthesis from cyanobacteria changed the earth and its atmosphere forever.1 The process involves the oxidation of water forming mol ecular oxygen releasing it into the atmosphere. Eventually the earths atmosphere chang ed from anaerobic to aerobic leading to a dramatic increase in biodiversity. L ife has since evolve d using oxygen leading to eukaryotic organisms and plants containing chloroplasts for photosynthesis and eventually hemoglobin in the red blood cells for the respiration of vertebrates (Figure 1 1) It is from the desire of scientist to understand these vital life processes that porphyrins were discovered. A B Figure 11. Chlorophyll and heme are two naturally occurring porphyrins A) Microscope image of chloroplasts visible in the cells of Plagiomnium affine B) SEM image of human red blood cells which contain the iron porphyrin heme

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16 The main historical events that led to the discovery of porphyrins has been the subject of many reviews and summarized by Sheldon.2 The existence of iron in human blood was first reported in 1747 when Menghini burned human blood to ash separating parti cles of iron with a magnet. Later the experiments by an English chemist named Joseph Priestly in 1774 proved that the oxygen consumed by fire and breathing animals could be restored to the air by plants. This ignited interest in understanding the role of oxygen in respiration. In 1841, treating powdered blood with sulfuric acid Sch erer was able to isolate the iron free pigment in blood. A German chemist named Felix HoppeSeyler in 1864 was able to isolate the ironcontaining oxygentransport metalloprotein found in red blood cells naming it hemoglobin. Later in 1871 Hoppe Seyler iso lated porphyrins from blood and proved they were pyrrole derivatives and is credited with noting the structural similarities between chlorophyll and heme in 1879. It was not until 1912 that the correct structure for porphyrins was proposed by K ster although at the time not accepted. Milroy published t he first general synthesis of porphyrins in 1918.3 L ater the work of Hans Fischer in 1926 who was awarded the N obel Prize in 1930 for his work in 1929 the de novo synthesis of chlorohemin which proved the structure proposed by K st er almost twenty years earlier.4 Structure and Nomenclature of Porphyrins Fischer also developed the first system of nomenclature outlined in his book Die Chemie des Pyrrols published in 1934 for the naming of porphyrin compounds.5 The general unsubstituted structure of a porphyrin is often referred to as porphine and is outlined in Figure 12 Substitution can occur at two positions along the periphery of the macrocycle in the carbons of the pyrrole fragments or at the four meso positions which are the methine bridges between the carbons of the pyrrole fragments. The

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17 nomenclature developed by Fischer is frequently used today, although another system was developed in effort to name more complicated structures where the Fischer nomenclature failed. Figure 1-2 Porphyrin nomenclature developed by Hans Fischer.5 A) Nomenclature for porphyrin positions B) Numbering for positions C) Greek letter notation for meso positions T he nomenclature developed by the International Union of Pure and Applied Chemistry (IUPAC) was adopted in the early 1970s ( Figure 1-3).6 This nomenclature differs from Fischers in that all the carbon and nitrogens in the porphyrin macrocycle are given a number. Where previously in Fischers nomenclature carbons were not numbered because they could not be substituted and the meso positions w ere denoted by Greek positions then become 2,3,7,8,12,13,18, and 17 instead of 1 8. The meso positions are numbered 5,10,15,20 in place of the Greek letters Fischer previously assigned. Figure 1-3 The numerical IUPAC nomenclature for porphyrins.6 A) positions B) Numbering for meso positions C) Complete IUPAC numbering Naming porphyrins is relatively simple when all the substituents around the macrocycle are the same. Two examples would be if all the meso positions w ere

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18 substituted with phenyl substituents to give tetraphenylporphyrin ( H2TPP) and alternatively if all the positions were substituted with ethyl groups to give octaethylporphyrin ( H2OEP). However the naming of porphyrins becomes increasingly difficult with lower symmet ries arising from different substituents at either the or meso positions. History of Porphyrin Synthesis The need for developing practical and efficient synthetic methods for the preparation of porphyrins was born when Fischer confirmed the porphyrin structure in 1929. The significant biological roles and photophysical properties of porphyrins has driven the attention of researchers over the past century. Although at first th o rough exploration of these compounds has been severely limited by their synthe tic availability This provided the inspiration for synthetic chemist s to develop efficient synthetic methods for their preparation. It is worthwhile to examine the history and synthetic advancements made to completely appreciate the progress that has bee n made in this field. Figure 1-4 Outline of the most common substitution patterns found around the porphyrin macrocycle. A) and meso unsubstituted porphine B) substituted OAPs C) meso aryl substituted porphyrin The synthesis of porphyrins can be divided into three main categories consisting of the and meso unsubstituted porphine; substituted porphyrins referred to as ocatalkylporphyrins (OAPs) and finally meso aryl substituted porphyrins. These

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19 structur es are illustrated in Figure 14 Since the focus of this work is on meso aryl substituted porp hyrins the initial synthetic strategies developed for the synthesis of porphine and OAPs will not be examined and have already been well reviewed.7 It is worth noting that both porphine and OAPs closely resemble the porphyrins found in biological systems. This chemistry was developed in order to synthesize naturally occurring porphyrins such as heme and chlorophyll.4, 8 Synthesis of meso Substituted Porphyrins Although meso substituted porphyrins are not naturally occurring compounds they have provided chemist s and other scientist with a multitude of applications and fundamental studies. This stems fro m t he simplicity in their preparation where one pot synthesis are normal On the other hand porphyrins with biological relevance are unsymmetrical and therefore cannot be prepared via simple routes .7 This is the attraction to meso substituted porphyrins where their symmetry enables their simple preparation from starting materials such as pyrrole and benzaldehyde.9 The initial work on meso substituted porphyrins began in 1935 when Rothemund first developed a method for the synthesis of meso tetramethylporphyrin from heating acetaldehyde and pyrrole in methanol at 95C.10 Rothemund later expanded the s cope of this method to include a variety of aromatic aldehydes in 1936 including benzaldehyde to yield H2TPP.11 In 1941 Rothemund described in detail the preparation of H2TPP in a reported 7 9% yield from heating 10 mL of pyrrole and 20 mL of benzaldehyde in 20 mL of pyridine at 220C for 48 hours.12 The Rothemund method can be summarized as using high reactant concentrations at high temperatures in absence of an added oxidant.

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20 Improvement in the synthesis of meso substituted porphyrins came in the mid1960s from Alder and Longo. The new method utilized lower reactant concentrations compared to the Rothemund method. The reactants were heated in acidic solvents with the reaction vessels open to air. This enabled the preparation of a variety of meso substituted porphyrins in a 3040% yield.13, 14 Optimized conditions were obtained by increasing the reactant concentrations and using propionic acid (bp 141C) rather than other lower boiling acidic solvents like acetic acid. Heating the reaction to reflux ope n to air and then cooling yielded crystals of the desired porphyrin.14 This advancement prompted a mechanistic study by Dolphin who examined the condensation of 3,4dimethylpyrrole with benzaldehyde in refluxing acetic acid under anaerobic conditions. This led to the formation of the porphyrin precursor octamethyltetraphenylporphyrinogen which could then be oxidized to octamethyltetraphenylporphyrin.15 This result is important as it provides very strong evidence that the precursor porphyrinogen is formed followed by oxidation to the porphyrin. Figure 1-5 Outl ine of the synthetic conditions for the preparation of meso aryl substituted porphyrins by Lindsey in 1987.16, 17 It was not until the late 1980s that Lindsey et al reported a new synthetic method that set the s tandard for meso aryl substituted porphyrin.16, 17 The methodology allows for a wider variety of substituted aldehydes to be incorporated into the subsequent porphyrins. The reaction can be scaled up to provide gram scale quantities and is reproducible with typical yields in the range of 3040% for substituted benzaldehydes

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21 Lindsey et al developed this method as a single flask two step reaction based on equilibrium cyclizations and biomimetic studies of porphyrin biosynthesis and is outlined in Figur e 15 The first step is the acid catalyzed condensation to form the intermediate porphyrinogen, followed by the second step the addition of an external oxidant such as DDQ or chlorinal to form the porphyrin. The method was developed on the premise that tetr aphenylporphyrinogen would be the thermodynamically favored product from the condensation of pyrrole and benzaldehyde under favorable conditions. Also important were to keep the reaction conditions mild utilizing the fact that benzaldehyde and pyrrole are reactive molecules and high temperatures are unnecessary. This enabled new functionalities on substituted benzaldehydes to be compatible with the given reaction conditions The previous methods used harsh reaction conditions which limited the scope of poss ible substituents available at the mes o position. Extended Porphyrins fused benzene rings represent an interesting class of compounds. The structures for tetrabenzoporphyrin ( H2TBP), tetranaphthoporphyrin ( H2TNP), an d the related phthalocyanine (Pc) are outlined in Figure 1 6 The TBP and extended porphyrins caught the attention of researchers early on for their photophysical properties relative to those of regular porphyrins. The effect on the optical properties of the porphyrin macrocycle from fused benzene rings was studied by the Gouterman in the 1960s.1820 The se studies provided the data that set forth the motivation to develop efficient synthetic methods to a ccess these compounds for further characterization and use in a multitude of applications

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22 Figure 1-6 General structures for phthalocyanine and meso extended porphyrins: A) Phthalocyanine (Pc), B) Tetrabenzoporphyrin ( H2TBP), C) Tetranaphthoporphyrin ( H2TNP). The initial methods to synthes ize TBP s were derived from that of Pc chemistry developed by Linstead in 1934.21 It was later in 1940 that Tuey and Linstead successfully produced H2TBP and its azasubstituted derivatives .22, 23 The method involves heating 3carboxymethylphthalimide above 300C in the presence of zinc or zinc acetate to give the zinc (II) tetrabenzoporphyrin (ZnTBP) in a very low yield ( Figur e 1-7) Analytically pure samples were obtained by sublimation or crystallization. The authors were able to isolate the f ree base (H2TBP ) after treating the zinc complex with acid enabling the synthesis of the respective copper and iron complexes. This method was later refined by Gouterman in 1976 obtaining ZnTBP in a 14.5 % yield,18 a lthough extensive purification was required. The c rude sample was sublimed and then further purified by multiple chromatography columns. The final product was obtained by precipitation into methanol. Finally a method developed by Kunkely and Volger in 1978 provided ZnTBP and was regarded as the simplest way to synthesize the TBP macrocycle.24 It requires heating 2acetylbenzoic acid to high temperature with ammonia and zinc acet ate (Figure 1 8). This affords ZnTBP in a moderate 17% yield and until recently was

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23 regarded as the most direct and convenient method for synthesizing the meso unsubstituted TBP. Figure 1-7 Initial synthetic strategy developed by Linstead and Tuey for the preparation of TBP A) Linstead synthesis of Pc in 193421 B) Linstead synthesis of TBP in 1940.22, 23 Figure 1-8 Synthetic scheme reported by Kunkely and Volger in 1978 for the preparation of ZnTBP .24 Researchers eventually developed synthetic methods for the preparation of tetraaryltetrabenzoporphyrins ( H2Ar4TBP). The synthesis was motivated by the idea of combining the properties of H2TPP with the TBP structure. The early reports for the synthesis of H2TPTBP were developed from strategies analogous to the reported methods for preparing H2TBP ( Figure 1-9) The ini tial method appeared in 1981 described by Kopr anen kov et al used 3benzylidenephthalimide or alternatively the potassium salt of phthalimide and phenylacetic acid with zinc acetate to give ZnTPTBP (Figure 1 -9 B) .25 Two years later, Remy published a method using the most logical

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24 retro synthetic precursor of the TBP macrocycle.26 The high temperature condensation of isoindole with benzaldehyde and zinc acetate also afforded ZnTPTBP (Figure 1 -9 C) Although earlier in 1972 Bonnet had published a communicat ion describing the instability of isoindole and the rapid decomposition at room temperature.27 Thus th e reproducibility of these methods was scrutinized by other groups that r eported mixtures of products identified as TBP s with varying numbers of meso aryl substituents.2830 Later in 1991, Ohno et al showed that using zinc benzoate in place of zinc acetate with 3benzylidenephthalimide heating to high temperatures yielded ZnTPTBP without side products (Figure 1 -9 A) .29 Figure 1-9 Outli ne of synthetic strategy to prepare H2TPTBP A) Ohno et al synthesis of H2TPTBP without side products29 B) Kopranenkov et al synthesis of H2TPTBP25 C) Synthesis of H2TPTBP from isoindole r eported by Remy.26 extended porphyrins was developed by Ono et al .31, 32 The new method uses a bicyclic pyrrole precursor serving as a protected form of the simplest retrosynthetic precursor isoi ndole. This enabled the cyclization of the porphyrin macrocycle to occur under mild Lindsey conditions avoiding the high temperature reactions of Pc based related strategies The key starting material 4,7dihydro4,7 ethano2H isoindole was prepared from a Barton Zard pyrrole synthesis outlined in Figure 110 This synthetic strategy yielded the bicyclic TPTBP precursor

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25 under Lindsey conditions in a 35% yield. The solid state retro Diels Alder (RDA) reaction requires temperatures of 200C and produces ZnTPTBP quantitatively with no required purification. This method is powerful in avoiding the major pitfall of the previous methods which required much higher temperatures and extensive purification with low er yields in comparison. Figure 110. The synthesis reported by Ono et al for the preparation of H2Ar4TBP using L indsey conditions and a bicyclic pyrrole as a protected form of isoindole.31, 32 Using a similar synthetic strategy to the one developed by Ono, another method extended porphyrins was developed by using a different approach to a maskedisoindole derivative. This method was developed by Cheprakov et al in 2001 and is based on using tetrahydroisoindoles as the key starting material.33 The synthetic scheme is depicted in Figure 1 11. The tetrahydroisoindoles are prepared from a modified Barton Zard synthesis to produce the cyclic pyrrole from vinyl sulfones instead of nitro alkenes.34, 35 After cleavage of the ester, the deprotected pyrrole is subjected to Lindsey conditions and gives the tetracyclohexenoporphyrin precursor in good yields. Attempts at aromatizing the free base porphyrin directly by refluxing with DDQ failed to give H2TPTBP. Alternatively the precursor porphyrin was metallated and

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26 then subjected to oxidizing conditions with ex cess DDQ in T HF to give the metallated TPTBP s in near quantitative yield. This methodology has advantages over Onos method in that it broadens the scope of meso aryl substituents compatible with the reaction conditions. However despite the improvement over the retro Diels Alder approach which requires temperatures at 200C, this method still suffered from over oxidation of the TBP s due to the long reaction times required in the oxidative dehydrogenation with DDQ. This drawback led to further improvements to the present oxidative aromatization method for the preparation of extended porphyrins. Figure 111. Outline of the oxidative aromatization strategy for the preparation H2Ar4TBPs reported by Cheprakov et al .33 A recent paper by Cheprakov and Vingradov in 2005 describes the synthesis of H2Ar4TNPs using the oxidative aromatization methodology previously described.36 The advancement in synthetic strategy is in choosing the pyrrole precursor to resemble isoindole as much as possible. The two key starting materials examined are cis octalin and 1,4dihydron aphthalene (Figure 112). The pyrroles for each strategy were synthesized in a parallel manner to the scheme used for the H2Ar4TBP synthesis. The pyrrole from the cis octalin route was condensed with an aromatic aldehyde under

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27 Lindsey conditions and provided the tetraaryl cycloalkenefused porphyrin. This precursor to the H2Ar4TNP syste m was metallated and then subjected to oxidative conditions with DDQ under reflux. The highest yield obtained from this route was 4045% from the palladium complex. The copper complex provided the H2Ar4TNP in a 20% yield and efforts to oxidize the zinc complex resulted in demetallation and the formation of a porphyrin dication. In comparison to the analogous H2Ar4TBP system the cis octaline scheme to prepare H2Ar4TNPs is less efficient Figure 112. Synthetic strategy for H2Ar4TNP using the dihydroisoindole method developed by Vinogradov et al .36 A) O ctalin strategy towards H2Ar4TNP B) D ihydroisoindole strategy towards H2Ar4TNP. Alternatively the route from the key starting m aterial 1,4 dihydronaphthalene smoothly gave 4,9dihydro2H benzo[ f ]isoindole which under Lindsey conditions in the presence of an aromatic aldehyde gave the desired H2Ar4TNPs after the addition of DDQ. Despite the authors efforts they were not able to isolate the intermediate porphyrin, which was possible in both the previous octalin and TBP schemes. The overall yield from the Lindsey condensation ranged between 3550% providing excellent access to the H2Ar4TNP system without the requirement of a metallat ion/demetallation

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28 step. This new strategy was termed the dihydroisoindole method and later applied to the H2Ar4TBP and the tetraanthroporphyrin ( H2Ar4TAP) systems.37, 38 This strategy represents the most powerful method extended porphyrins. In both the H2Ar4TNP and H2Ar4TAP systems the oxidative aromatization occurs almost instantly with the intermediate porphyrins to date not isolated. Only in the H2Ar4TBP system must the temperature be elevated to 100C for a short period of time to complete the oxidative aromatization. Introduction to Photophysics The interaction of light with matter is something that has caught the interest of scientist since the early 15th century. At the end of the 19th century it was generally accepted that light was a wave and electrons were particles. In the beginning of the 20th century Plancks blackbody experiment concluded that blackbody radiation was limited to finite values of energy. This meant that the energy was quantized and changed the views of light as a wave. Einstein later discovered the photoelectric effect, further cementing the idea of light having wave and particle like properties. Although for most purposes the Maxwell wave equations from 1860 generally explain most of the light related phenomena. These findings laid the foundation for de Broglie in 1924 to theorize that all particles act as waves. This led to the Schrdinger equation in 1924 which enabled the description of the wave nature of electrons mathematically. The impact of these discoveries has dramatically changed our understanding of atomic and molecular structure. Absorption of Light When light interacts with matter it has three possible pathways in that it is either reflected, tra nsmitted or absorbed by the material. The latter pathway often referred to

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29 as absorption can provide important information regarding the electronic molecular structure of a molecule. The absorption of a photon promotes a ground state electron to a higher e nergy level called an excited state. The difference in energy between these two energy levels is equal to the energy of the absorbed photon. This allows for elucidation of the molecular energy levels of a molecule. The energy of a photon is proportional to the frequency of its electromagnetic wave and is described by the following equation: (1 1) where E is the energy of the photon, h is Plan cks constant, v is the frequency, c is the speed of light, and is the wavelength of the photon. Since the electronic energy levels of a molecule are finite the ground state electrons absorb photons of different wavelengths (different energy) with differ ent efficiencies. The efficiency of which a certain wavelength of light is absorbed is described by the molar absorptivity which is described by Equation 12. (1 2) W here A 1 cm1), and b is the path length of absorption and C representing the molar concentration of the absorbing compound. The molar absorptivity represents the probability of the transition to occur an d is directly related to the transition dipole moment between the initial and final states. Another important principle to understand is the Franck Condon principle. This explains why the absorption bands in molecules appear as broad bands instead of the p redicted sharp lines based on the discrete electronic energy levels. This is not the case

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30 because of the difference in time scale between the excited electron (1015 s) and the readjustment time of the nuclei (1013 s) and is referred to as the Franck Con d on principle (Figure 1 13). Figure 113. Potential energy curves for electronic transitions. A) Electronic transitions between states of similar equilibrium nuclear geometry. B) Electronic transitions between states of different equilibrium nuclear geometry. This figure was adopted from Gilbert and Baggot.39 This is illustrated by potential energy curves of the ground and excited states as a function of equilibrium geometry. The electronic transitions are termed vertical to illustrate absorption occurring without any changes in the equilibrium geometry. This allows for electrons to be promoted to higher excited states regardless of any

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31 differences in equilibrium geometry between the ground and excited state. After absorption the molecule will relax to the lowest vibrational excited state (v = 0). This relaxation results in a loss of energy and is the reason why the energy between the ground state (v = 0) and some vibrational excit ed state (v > 0) will always be higher in energy than the 00 transition. Nature of the Excited State Following absorption of a photon from the ground state (S0) the electronic excited state (S1) is created and represented by a vertical arrow (solid) in t h e Jablonski diagram (Figure 1 14). The molecule will first relax from higher vibrational levels (v > 0) to the lowest energy vibrational level (v = 0). This process occurs through two types of relaxation thermal (loss of heat) and collisional (with other molecules) and is illustrated by the dashed arrow. When the ground state is neutral the electrons in the highest occupied molecular orbital (HOMO) are paired and have opposite spins according to Hunds rule. When the electron is promoted to the excited sta te the spin is forbidden to change due to spin restrictions imposed by quantum mechanics and is therefore termed a singlet excited state (S1). It is possible in some cases for the spin of the excited electron to flip; this process is referred to as intersy stem crossing (ISC). This creates a situation where both electrons have the same spin. Excited states of this nature are referred to as triplet excited states (T1). Similar to the singlet excited state the vibrational energy level is greater than zero for the initially formed tripl et state and fast relaxation occurs to the lowest energy vibrational level (v = 0). Typically organic molecules have very low rates of ISC therefore the resulting triplet yields are very low. The rate of ISC can be enhanced by the addition of heavy atoms in a process known as the heavy atom effect. The process of ISC involves the conservation of total orbital angular momentum

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32 and in heavy atoms the spin angular momentum and orbital angular momentum are not individually conserved. T his facilitates spin orbit coupling and increases the rate of the electron spin flip to form the triplet excited state. This allows inorganic and organometallic compounds such as platinum porphyrins to have large triplet quantum yields. ISC v = 0 S 0 IC P IC F A S 1 T 1 IC IC v = 1 v = 0 v = 2 v = 3 v = 1 v = 2 v = 3 A: absorption F: fluorescence P: phosphorescence S 0 : groun d state S 1 : singlet excited state T 1 : triplet excited state IC: internal conversion ISC: inter system crossing Figure 114. Ja blonski diagram showing the possible transitions for a singlet excited state after absorption of a photon. Relaxation of the Excited States The triple t and singlet excited states are metastable, meaning they are stable and have long lifetimes but are transient in nature and eventually will relax to the ground state. The two pathways by which the self relaxation mechanisms can occur are radiative and nonradiative decay. The latter represents the return of the excited electron to the ground state without th e emission of a photon. Instead the energy is released as heat to the system when nonradiative decay occurs. This process and vibrational relaxation pathways are referred to as internal conversion (IC) on the Jablonski diagram (vertical dashed lines). The rate of nonradiative decay is governed

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33 by the energy gap law. This law states that as the gap (energy difference) between the excited and ground states becomes lower in energy the rate of nonradiative decay will increase exponentially. Simply put one co uld expect that a fluorophore emitting light at 450 nm would have a smaller nonradiative decay rate than a fluorophore emitting at 700 nm due to the smaller gap in energy between the excited and ground state. Photophysics of Porphyrins The aesthetically pleasing purple color of porphyrins is the direct result of their unique absorption. Understanding what gives rise to their fascinating optical absorption and emission spectra has been an intriguing topic for researchers. The 18 electrons in the 16mem bered porphyrin ring are responsible for the general optical spectra observed. However influences from external substituents and changes in conjugation pathway as well as change in the central substituents all lead to moderate to s trong changes in optical absorption and emission spectra. The characterization of porphyrin absorption and emission spectra based on substitution patterns and different central substituents has been well studied and review elsewhere. The focus of this work is on one class of metalloporphyrins specifically platinum (II) porphyrins. Absorption of Metalloporphyrins Metalloporphyrins typically differ very little by optical absorption spectra, but more so in emission from metal to metal. The addition of a metal to the center of the porphyrin changes the overall symmetry to D4h from the lower D2h symmetry of the freebase porphyrin. The absorption spectra for ZnTPP and Pt TPP in toluene are shown in Figure 1 15. Two visible bands are typically seen between 500600 nm called the Q band with molar absorptivity constants in the range of 1.22 x 104 M1 cm1. The Q bands is a quasi allowed transition. The lower energy band ( ) is separated by approximately 1250

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34 cm1 from the higher energy band ( ). The band represents the electronic origin of Q(0,0) of the lowest energy singlet excited state. One mode of vibrational excitation in the singlet excited state is denoted by Q(1, 0) and is represented by the band. The Soret band, often referred to as the B band, is an intense band to the blue of the Q band between 380420 nm and is strongly allowed. Typical molar absorptivity constants for this band are in the range of 24 x 105 M1 cm1. The electronic origin of the Soret band is B(0,0) of the second singlet excited state additionally with better resolved spectra another band appears to the blue (~1250 cm1) representing one mode of vibrational excitation B(1,0). Wavelength (nm) 300 400 500 600 Normalized Absorption 0.0 0.2 0.4 0.6 0.8 1.0 1.2 450 500 550 600 Figure 115. Examples of metalloporphyrin absorption spectra for ZnTPP (blue) and Pt TPP (green) in toluene with the Q band region magnified in the inset. The metalloporphyrins are classified into two classes called regular and irregular This is based on whether or not the coordinated metal has a closed or open shell of valence electrons. The metalloporphyrins classified as regular give normal optical absorption and emission spectra. The normal absorption spectra are primarily

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35 electrons with the atomic or b i tals of the coordinated metal molecular orbitals of the porphyrin ring. The irregular metalloporphyrins show spectra that are classified into three main types called normal hypso and hyper The orbitals of the coordinated metal have a much stronger effect on optical spectra due to stronger mixing with the porphyrins electrons. The metals from the dor f block where the metal electrons are lower in energy and do not sufficiently interact with t electrons give normal type absorption spectra. An example of this would be zinc tetraphenylporphyrin (ZnTPP). The hypsotype spectra also resemble the normal spectra but the Soret and Q bands are blue shifted relative to the freebase porp hyrins absorption spectra. This results from metals in the dblock with unfilled dorbitals (d6d9). The delectrons from orbitals of the porphyrin resulting in metal to ring charge transfer. This has the effect of incr transition and thus blue shifting the absorption spectra. The blue shift increases with atomic number of the transition metal for example in series of Ni(II), Pd(II), and Pt(II). Figure 116. Jablonski diagram sh owing the decay schemes for singlet and triplet relaxation after absorption of a photon. The radiation processes depicted as solid lines and radiationless processes as dashed lines.

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36 Introduction to Porphyrin Emission One of the first reports of emission observed from a porphyrin was from the reduced porphyrin chlorophyll in 1834. The ene rgy level diagram in Figure 116 illustrates the possible pathways of the singlet excited state (S1) after absorption of a photon from the singlet ground state (S0) Excit ation of the ground state S0 to any singlet excited state Sx leads to the population of the lowest singlet excited state S1 by very fast radiationless decay (~1012 1013 sec). The excited state S1 can radiatively decay (fluorescence) S1 S0 with a rate kf. From S1 there are two possible nonradiative decay path ways the first being relaxation back to S0 with a rate k1 and the second intersystem crossing to the lowest energy triplet state T1 with a rate k2. The triplet state (T1) can then radiatively decay to S0 (phosphorescence) with a rate kp. The first nonradi ative decay path way is back to the singlet ground state S0 with a rate k3. Alternatively through thermal repopulation or triplet triplet collisions repopulation of the singlet excited state (S1) may occur resulting in another nonradiative decay pathway followed by delayed fluorescence. Emission from Metalloporphyrins The insertion of a heavy m etal to form a metalloporphyrin causes a decrease in the fluorescence quantum yield from the expected increase in the rate of intersystem crossing from the heavy atom effect. The emission properties for regular metalloporphyrins are described by fluorescent q uantum yields in the range 1030.2 and phosphorescence quantum yields in the 1040.2 range. Emiss ion from the excited states for regular porphyrins occurs state of the porphyrin ring. The metal contributes small electronic perturbations resulting in small spectral changes or spinorbit perturbations which lead to larger variations in both fluorescent and

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37 phosphorescent quantum yields and tripl et lifetimes. Like free base porphyrins the regular metalloporphyrins give normal fluorescence spectra with two bands labeled Q(0,0) and Q(1,0). An example of this ty pe of porphyrin and emission is depicted in Figure 117 by ZnTPP. Wavelength (nm) 500 600 700 800 900 Normalized Emission Intensity 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Figure 117. Examples of metalloporphyrin emission in toluene for ZnTPP (red) and Pt TPP (purple) excited at the Soret band. Platinum porphyrins are an example of an irregular metalloporphyrin giving hypso type absorption spectra. The insertion of platinum increases the rat e of ISC such that phosphorescence (radiative decay ) is the dominant decay pathway. These phosphors are defined in many cases of having no observable fluorescence or quantum yields of fluorescence that are < 103. This is a result of very high rates of int ersystem crossing and leads to the phosphorescent quantum yields being much higher in the range between 1040.2 with the triplet lifetimes usually < 3 msec. The phosphorescence for Pt TPP which represents an irregular metallo porphyrin is shown in F igure 117. The emission spectrum is red shi fted relative to the fluorescence emission from ZnTPP due to the lower energy of the triplet state. The intensity of Q(0,0) is higher in Pt TPP than in

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38 ZnTPP, whereas the intensity of the lower energy band corresponding to Q(1,0) is higher in intensity relative to Q(0,0) in ZnTPP than in Pt TPP. Near IR Light Emitting D i odes : State of the Art The three major roles of porphyrins in nature were accurately defined by Gouterman as electron transfer, oxygen transfer, and photosynthesis.40 However, t he research area which encompasses p orphyrins has since broaden with scientist s finding new applications in different scientific disciplines and is well reviewed elsewhere.41 One such application for platinum porphyrins is in l ight emitting diodes (LEDs) which are devices fabricated from inorganic or organic materials sandwiched between two electrodes U pon application of an electr ic field these devices emit light. This process is known as electroluminescence (EL) and discussed further in more detail along with other aspects of LEDs in the introduction section of Chapter 3. Pt OEP was first reported and incorporated into an OLED by Thompson et a l .42, 43 The use of Pt OEP produced deep red emitting OLEDs with record high efficiencies at the time. The increase in overall device efficiency was attributed to the use of a phosphor over a fluorophore which is discussed in greater detail in Chapter 3. The deve lopment of LED devices that exhibit electroluminescence solely in the near infrared (N IR) has c ontinued to be a rapidly growing field over the past decade. The realization of devices with high efficiencies will enable new technology to be commerc ialized for use in infrared signaling and displays, telecommunications, and wound healing .4447 The earliest reports of near IR LEDs date back to the early 1970s fabricated from inorganic materials which yielded low overall device efficiencies. Today over a hundred publications in the field exist with less than twent y percent reported prior to 2000. The

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39 use of organic materials for electroluminescence was first reported in 1987 by Tang and Van Slyke.55 This eventually led to the first deep red and near IR organic LED report using buckminsterfullerene in 1991 by Katsumi et al .56 Today a variety of materials are reported for use in near IR LEDs, but in general the devices still suffer from low efficiencies. Much work is still needed in the design and synthesis of highly efficient emitters in the near IR spectral region for device applications. The majority of reports for near IR LED devices have reported external quantum efficiencies (EQE) of less than one percent. The EQE data and the peak electroluminescence wavelengths for some recent literature reports representing the highest efficiency devices to date for near IR LEDs is summarized in Table 1 1. Table 1 1 Recent literature reports of n ear IR LED d evices demonstrating the state of the art in terms of emission wavelength and device efficiency .4854 Year Molecule max (nm) Power Efficiency (EQE) Ref. 2001 Ln TPP (Ln = Yb 3+ or Er 3+ ) 977, 1560 -0.015%, 0.1% 48 2003 DDD (Zn porphyrin Trimer) 820 0.1% 49 2005 PPyrPyrPV (Copolymer) 800 60 nW/cm 2 Low 50 2005 PMOPV TBSV30 (Copolymer) 800 -0.01% 51 2005 PFO SeBSe 10 (Copolymer) 759 -0.20% 52 2007 Pt TPTBP (Pt porphyrin) 773 750 W/cm 2 at 12 V 6.3% 53 2008 PtPc (Pt Phthalocyanine) 966 80 W/cm 2 at 140 ma/cm2 0.3% at approx. 1 mA/cm 2 54 Pre vious work in our group focused on the synthesis and characterization of lanthanide mono porphyrin ate complexes as near IR emitters for LED applications.48 The lanthanide monoporphyrinate complexes were fabricated into near IR LEDs by blending them into conjugated polymers (Figure 1 18) The TPP ligand served as an

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40 antenna to sensitize the narrow near IR emissi on from the coordinated lanthanide metal. However these transitions are weak with photoluminescence quantum yields ge nerally well below one percent leading to device efficiencies well below half a percent. Figure 118. Lantha n ide based near IR e mission from lanthanide monoporphyrinate complexes towards near IR LED applications .48 Therien and Bazan in 2003 reported near IR PLEDs using ethynebridged zinc porphyrin fluorophores.49 A zinc porphyrin trimer (DDD) was doped into polymer host materials and electroluminescence observed at 820 nm. The overall performance of the device was rather low with an EQE of 0.1%. PLEDs fabricated from near IR emitting polymers have been reported.5052 Conjugated polymers in general usually have lower PL efficiencies and broad emission profiles. The use of these materials for LED applications is less than ideal and results in lower device efficiencies. An alternative to the Lanthanide porphyrin complex extended porphyrins which have been initially investigated since the 1940s. However use of these materials towards material science applications has been limited due to the difficulty in their preparation. The recent advances in the synthesi extended porphyrins made by Finikova et al have allowed access to these ideal targets for use in

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41 near IR LED device applications. The success in fabricating deep red emitting LED devices using Pt OEP cements the promise of these materials in this fi eld. Recently Thompson et al demonstrated the use of a platinum extended porphyrin as a near IR phosphor for use in a near IR LED (Figure 1 19) by incorporating platinum tetraphenyltetrabenzoporphyrin (Pt TPTBP) in an Alq3 host matrix. The optimized devi ce displays an electroluminescence peak in the near IR region at 772 nm with a record EQE for this wavelength region of 8.5%. Similarly a near IR LED based on a platinum phthalocyanine (Pt Pc) has also been reported with electroluminescence centered at 966 nm with an EQE of ~0.3%.54 Figure 119. Near IR OLED device data for Pt TPTBP doped in to Alq3 reported by Thompson et al .53 A) E lec troluminescence at 772 nm from Pt TPTBP doped in Alq3 B) E xternal quantum efficiency of 8.5% and optimized device structure. Extended Platinum Porphyrins as Near IR Phosphors Plat inum complexes of extended porphyrins have been demonstrated by Thompson et al to be ideal targets for application in near IR LEDs To t h e best of our knowledge only five platinum TBP derivatives have been reported, while no reports exist for the TNP and TAP systems .53, 57, 58 This is largely due to the difficulty in the preparation of the platinum complexes in good yield from the freebase porphyrins

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42 Therefore the development of metallation conditions to provide access to the platinum complexes of extended porphyrins is imperative and described in Chapter 2. The novel reaction conditions have allowed access to platinum TNP and TAP systems for the first time, where this work would otherwise not be possible. Figure 120 outlines the nearly all the known structures for free base and metalloTBPs w h ere Pt 1a and Pt 4b represent two of the known platinum complexes for extended porphyrins .32, 33, 5862 The other three platinum complexes are derivatives of Pt T PTBP were the meso aryl groups are fluorinated to different degrees.57 The PL spectra for Pt 1a and Pt 4b have maximum emission wavelengths reported at 765 and 745 nm respectively. The quantum yields of Pt 1a and Pt 4b are the highest reported for this wavelength region of 0.70 and 0.51 respectively. The previously reported freebase and metallo TNPs are shown in Figure 121.36, 58, 63 65 Completely absent is the report of a platinum complex, although quite a few palladium complexes have been reported. Zn =H2,Pd2C6H4;M=H2 6H4;M=H2O2C-C6H4;M=H2uPh;M=H22b:R=H;M=H2,Zn,Mg 3b:YCO2Me 3c:Y=Br 3d:Y=OMe 3e:Y=NO2M=H2,Cu,Ni,Zn,Pd 4b:RBu M=H2,Zn,Pd,Pt,Fe Figure 1-20 Current literature reports for free base and metalloTBPs.

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43 The PL spectra reported in the literature for PdTNPs are shown to have maximum wavelengths ranging from 920 950 nm depending on substitution of the TNP. This is over a 100 nm red shift compared to the emission of PdTBPs. The PL spectra from Pt TNPs will likely be blue shifted relative to the PdTNPs, following the same trend in platinum and palladium complexes for porphyrins and TBPs. The quantum yields range from 2 5% and are lower than the 6.7% reported for a PdAr4TBP derivative. The quantum yields for Pt TNPs should be expected to be higher than the PdTNPs based on the observed trend in the PdTBP (0.067) and Pt TBP (0.51) derivatives. This data suggest that a Pt TNP derivative will likely have a high PL efficiency for this wavelength region making it an ideal candidate for near IR LED applications. Figure 1-21 Current literature reports for free base and metalloTNPs.

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44 Recent literature reports for TAPs suggest that PL from a Pt TAP should be centered beyond a 1000 nm. To date there are only a couple reports on PL from TAPs.38, 66 Ono et al report the fluorescence and quantum yield data for ZnTAP derivatives. The reported emission maxima are ~820 nm. There is only one known report of a phosphorescent TAP reported by Cheprakov et al They report a PdTAP porphyrin with the PL centered at 1107 nm and a phosphorescence quantum yield of less than 0.5%. There are no reports for a Pt TAP and the photophysical properties remain unknown. However, the preparation of a Pt TAP derivative will allow access to a new wavelength region in the near IR. Figure 122. Current literature reports for free base and metalloTAPs. Objective of Present Study ext ended platinum porphyrins beyond the TBP system to the TNP and TAP systems. A novel metallation procedure is reported herein providing access to the platinum complexes in high yield for the first time. The photophysics of these materials will be reported f or the first time in both solution and in thin films. The present study will also aim to optimize

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45 the porphyrin macrocycle through chemical modification by looking at the effects on solution and film photophysical and device properties of different substit uents and substitution pattern extended platinum porphyrins in an attempt to increase the device effi ciencies. This optimization should lead to higher phosphorescence quantum yields and reduced aggregation in a solid state matrix. Devices will be fabricated by two methods the first being from materials that are vapor deposited (sublimation) onto a substrate termed organic light emitting diodes (OLED) devices. The second methodology uses solution processing to form thin films of conjugated polymers doped with the extended porphyrins by spin coating the materials onto the device substrate referred to as PLED devices. The overall goals for device efficiencies (EQE) are to produce an OLED device with electroluminescence solely in the near IR spectral region operating at external quantum efficiency greater than 10%. The efficiency goals for a PLED device are to fabricate a device that operates at an overall efficiency greater than 1% with electroluminescence solely in the near IR.

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46 CHAPTER 2 SYNTHESIS O F EXTENDED PLATINUM PORPHYRINS Introduction The advances in synthetic methodology from the recently developed dihydroisoindole technique for preparing extended porphyrins has provided researchers with access to materials once thought inaccessible. Thomps ons group recently demonstrated a highly efficient near IR OLED device using Pt TPTBP as the near IR phosphor .53, 67 This work along with the recent reports of the synthesis of TNP and TAP system s are encourag ing for further development of new extended platinum porphyrins as NIR phosphors. While the freebase porphyrins and a few metal compl exes have been reported for each of these systems, the platinum complexes are still unknown.36, 38 T he published absorption and emission data for TBP, TNP and TAP systems (Figure 2 1) was reviewed in Chapter 1. The increase in conjugation to the porphyrin macrocycle via additional fusedbenzene rings systematically red shifts the absorption and emission spectra.58 Figure 21. General structures for meso extended porphyrins. The present study presents three novel series of extended platinum porphyrins. T he goal of the first series is aimed at pushing device emission further into the near IR by the addition of fusedaromatic rings to the porphyrin macrocycle. The second series

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47 of target TBPs focuses on increasing the solution quantum yield of platinum TBPs by varying the number of meso aryl substituents around the porphyrin macrocycle in attempts to understand the factors that control the emission yield The third series presents platinum TBP s designed to increase device efficiencies by chemical modification to the porphyrin macrocycle incorporating new substituents to either enhance mixing with the host or by preventing the porphyrin from aggregatin g. The target extended platinum porphyrins are outlined in Figure 22. O nly four of the free base porphyrins h ave been previously reported in the literature (H2TPTBP, H2TPTNP, H2DPTBP, and H2Ar2TBP). More importantly only one of the ten subsequent platinum complexes has been previously reported and studied (Pt TPTBP) Demonstrating the degree of which the platinum complexes for extended porphyrins have been under studied. The recent synthetic methodology has allowed the preparation of the freebase porphyrins while the synthesis and characterization of the platinum complexes has been absent from the literature due to the difficulty in their preparation. The following series of target extended platinum porphyrins has been prepared in efforts t o characterize the photophysical properti es of these novel phosphors in most cases for the first time. The first series of extended platinum porphyrins are outlined in Figure 22 The series is aimed at the preparation of platinum porphyrins wi th l onger emission wavelengths across the series from Pt TPTBP to PtAr4TAP The solution phosphorescence of Pt TPTBP has been reported at 773 nm. The emission wavelength can be further shifted by the preparation of Pt TPTNP. Recently Finikova et al report ed the phosphorescence of PdAr4TNP s beyond 900 nm and noted that substitution with

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48 eight methoxy substituents further red shifted the emission to 957 nm.36 This makes Pt TPTNP and Pt Ar4TNP(OMe)8 attractive candidates for NIR LEDs with expected emission wavelengths beyond 900 nm Later Yakutkin et al report ed the synthesis of Pd Ar4TAP derivative and meas ured the phosphorescence at 1107 nm The synthesis of Pt Ar4TAP would like ly provide access to emission beyond 1000 nm The platinum complexes for TNP and TAP systems have not been reported in the literature and thus the photophysical properties remain unknown to date. The second series of target platinum TBPs is aimed at increasing the solution quantum yield across the series from Pt TPTBP to Pt Ar2TBP. The solution quantum yields of Pt TPP ( 0.07 ) and Pt OEP (0.45 ) have been well studied.43, 68 The large difference in quantum yields is attributed to the increased planarity of Pt OEP. T he effects of the number of meso aryl substituents on the structural and photophysical properties i n the TBP system was recently studied for a seri es of free base and Pd TBPs.61 The quantum yield for Pd Ph2TBP is reported to be twice that of Pd Ph4TBP due to increased planarity of the TBP macrocycl e The proposed series of tetraaryl and 5,15diaryl platinum TBPs are outlined in Figure 22 It is expected that the solution quantum yields for Pt DPTBP and Pt Ar2TBP should follow the reported trend for PdTBPs l ikely leading to significantly higher qu antum yields and device efficiencies The past decade has seen a surge in the complexity of the fluorophores and phosphors synthesized for use in LEDs. The early work was focused on finding materials that displayed electroluminescence at specific regions i n the visible (blue, green, and red) with high quantum yields. However despite the advances made in the

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49 field quenching of the emitting species from intermolecular interactions or poor carrier mobility within the device matrix remains a problem.69 Figure 2-2 Target free base and platinum porphyrins towards new near IR phosphors The use of dendrimer encapsulated phosphors has proven effective in reducing aggregation problems.7073 The area of porphyrin dendrimers is a growing field with the

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50 new materials being applied to a variety of applications.74 Fluorescent porphyri n dendrimer systems have been reported for use in LED device applications with improvements reported in device efficiencies over other fluorescent porphyrin systems.75 Only one platinum porphyrin based dendrimer system has been reported for LED applications displaying higher device efficiencies than those reported for pure Pt OEP or PVK: Pt OEP devices.76 Unfortunately t he synthesis of dendrimers is lengthy and often accompanied by difficult purification making targets of this nature impractical Recently porphyrins have been reported with bulky meso aryl substituents that in effec t create the desired dye encapsulation obtained by a porphyrin dendrimer system noted by an increase in the solution quantum yield.77 The fl uorescence quantum yields for some reported TPP derivatives are reported to be twice that of TPP from the reduction in porphyrin aggregation in solution. The target Pt TBP structures in series 3 are aimed at reducing aggregation effects or increasing host compatibility in the device m atrix (Figure 2 2) The structures are based on recent literature reports for similar porphyrin systems.7779 In the work described in the present chapter, we report the design and synthesis of three novel series of extended platinum porphyrins. The freebase porphyrins have been prepared using the dihydroisoindole method. The platinum porphyrins have been prepared from a novel metallation procedure developed herein. The materials have been characterized by 1H and 1 3C NMR an d HRMS The photophysical properties for each series have been studied and are reported in C hapter 3 along with the performance for each material as near IR phosphors in near IR LED s.

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51 Synthesis of Aromatic Aldehydes for -E xtended P orphyrins The synthetic scheme for the target aromatic aldehydes is outlined below in Figure 2-3 along with commercially available benzaldehyde ( 1 ) Aldehyde 3 was prepared starting from commercially available 2 which was brominated with NBS and then subjected to oxidation/hydrolysis with hexamine to produce 3 in moderate yield following a previously reported method.80 Fig ure 2-3 Synthetic s cheme for aromatic aldehydes towards meso aryl substituted extended porphyrins Reagents and conditions : i) NBS, CCl4, 12 h reflux, h examine, MeOH, H2O reflux 4 h; i i) n BuLi, DMF, ether, 78 C, 30 min ; i ii) Pd(PPh3)4, Na2CO3,4 -tBuPhB(OH)2, PhMe, THF, H2O, 100 C, 120 h ; iv ) Br Hexyl NaOH, DMSO, H2O, 80 C overnight; v ) Pd(PPh3)4, N a2CO3,4 formylPhB(OH)2, THF, H2O, 80 C, overnight Aldehyde 6 was prepared in analogous manner to the reported 3,5diphenylbenzaldhyde.77 Treating 1,3,5 tribromobenzene ( 4 ) with one equivalent of n B uLi followed by the addition of DMF gave 5 in good yield.81 Compound 5 was then introduced to Suzuki coupling with 4tert butylphenyl boronic acid yielding aldehyde 6 in go od yield.77 The preparation of 9 followed a previously reported method.82 The alkylation of 2bromo fluor ene was performed by a previously reported method to give 8 in excellent yield.83 Compound 8 was introduced to a Suzuki coupling with 4formylbenzeneboronic acid to give aldehyde 9 in good yield.

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52 Synthe sis of P yrroles for -E xtended P orphyrins The synthesis of six of the eight free base TBP s share a common intermediate in 2ethoxycarbonyl 4,7 dihydro2H isoindole ( 18a ) which was prepared according to a previously reported method (Figure 2-4 ).37 The other two TBP derivatives required a substituted butadiene to access the desired pyrroles. Figure 2-4 Synthetic scheme for benzopyrroles 18a-b towards TBPs. Reagents and conditions : i) HCl, 25 C, 1h; ii) (EtO)2P(O)Cl, pyridine 0 C, 2 h; iii) THF, CuI, 0C25C, overnight ; iv ) DCM, AlCl3, TsCl, 24 h, 25 C; v ) MeOH NaF in H2O, 0C 25C, 1.5 h; vi ) 13 neat 25 C, 12 PhMe 130C 48 h; vi i ) THF, tBuOK CNCH2CO2Et, 0C 25C, 4 h. The 2,3substituted butadiene 12 was prepared according to a previously reported method. Following a published procedure compound 11 was prepared by treating commerci ally available 10 with diethyl chlorophosphate in the presence of pyridine to give 11 in good yield. The addition of an alkyl Grignard reagent to 11 gave the desired 2,3 substituted butadiene 12 in moderate yield The Diels -A lder adducts 17a -b where prepar ed from butadienes 12 and 13 Starting from commercially available 14 treated with a solution of AlCl3 and TsCl in dry DCM to afford the alkylation adduct 15 in good yield.84, 85 Compound 15 was converted to ethynyl ptolyl sulfone ( 16 ) following a published procedure by deprotecting 15 with aqueous sodium fluoride in methanol to give 16 nearly q uantitativ ely.86 The Diels Alder adduct 17a was obtained by reacting 16

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53 in neat 1,3butadiene ( 13) to give 17a in good yield following a previously reported method Similarly 17b was prepared from 16 and 12 from a modified literature method to give 17b in good yield. Dropwise addition of the vinylic sulfones 17a-b to a one equivalent tBuOK and ethyl isocyanoacetate mixture in dry THF in a modifi ed BartonZard synthesis gave benzopyrroles 18a-b in good yield. Figure 2-5 Synthetic scheme for naphthopyrroles 21 and 26 towards TNPs Reagents and conditions: i) PhSCl, DCM, 0 C, 1 h, m CPBA, 0C 25C, 1 h; ii) THF, tBuOK CNCH2CO2Et, 0C reflux, 1 h; iii) AcOH, 25 C, 24 h; iv ) Me2SO4, K2CO3, acetone, reflux 40 h; v ) PhSCl, DCM, 0C25C, 2 h, m CPBA, 0C 25C, 1 h; vi ) THF, tBuOK CNCH2CO2Et, 0C reflux, 1 h The synthesis of naphthopyrroles 21 and 26 have been previously reported and is outlined in Figure 2-5.36 Pyrroles 21 and 26 were similarly prepared from commercially available 1,4dihydronaphthalene ( 19 ) and 5 ,8 dimethoxy derivative 23. Starting from commercially available 1,3butadiene and 1,4 benzoquione ( 22 ) in acetic acid at room temperature gave the Diels Alder adduct 23 in a moderate yield.87 Compound 23 was treated with potassium carbonate and dimethyl sulfate in refluxing acetone to give 24 in an excellent yield.87 chlorosulfones 20 and 24 were prepared from the dropwise addition of phenylsulfenyl chloride (PhSCl) in dry DCM to 19 and 23 followed by oxidation with m chlorosulfones 20 and 24 in good yield. The pyrrole esters 21 and 26 were obtained in good yields and prepared analogously to 18a

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54 from a modified Barton Zard synthesis requiring an extra equivalent of base to form the vinylic sulfone in situ from the protected chlorosulfone. The anthropyrrole precursors 32 and 38 that provide access to the TAP system were prepared from previously reported literature methods.38, 66 The key intermediates for the pyrrole synthesis are 1,4dihydroanthracene ( 35) and bicyclic precusor 30 Compound 30 was prepared s tarting from 1,4 naphthoquione ( 27 ) and 1,3 cyclohexadiene in refluxing ethanol to give the Diels Alder adduct 28 in a good yield.88 The reduction of dione 28 in anhydrous methanol with sodium borohydride smoothly gave the diol 29 in excellent yield.89 Figure 2-6 Synthetic scheme for anthropyrroles 32 and 38 towards TAPs Reagents and conditions: i) EtOH, 3 h, reflux; ii) MeOH, NaBH4, 0 C, 2h; iii) Pyridin e, TsCl, 48 h, 25C; iv) PhSCl, DCM, 78C25C, 4 h, m CPBA, 0C 25C, 18 h; v) THF, tBuOK CNCH2CO2Et, 0C 25C, 18 h; v i) Pyridine 3 sulfolene, NaHCO3, 120C, 70 h; v ii) EtOH, HCl, reflux, 24 h; v iii) PhSCl, DCM, 78C25C, overnight, m CPBA, 0 C25 C, 48 h; ix) DCM, DBU, 25 C, 1 h; x ) THF, tBuOK CNCH2CO2Et, 0C 25C, overnight. The dehydration of 29 with excess tosyl chloride in dry pyridine yielded 30 in good yield .90, 91 Key intermediate 35 was obtained starting from 33 which was prepared from a literature procedure from benzyne and furan.92, 93 Compound 33 was treated with 3 sulfolene while heating in pyridine to yield the Diels Alder adduct 34 in good yield.

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55 Compound 34 was then intr oduced to refluxing e thanol and HCl to give 3 5 in a good yield. The reported method of preparing 3 6 using Oxone as the oxidant failed. chlorosulfones 31 and 3 6 were obtained from a modified procedure for 20.66 T he dropwise addition of PhSCl in dry DCM to 30 and 3 5 at 78 C followed by oxidation with m CPBA for 18 to 48 hours gave 31 and 3 6 in good yields. Pyrrole esters 32 and 3 8 could be prepared directly from chlorosulfones 31 and 3 6 forming the vinylic sulfone in situ to give the anthropyrroles in moderate yield. Alternatively 3 8 could also be prepared in a similar yield from the deprotection of 3 6 to allylic sulfone 3 7 with DBU. Allylic sulfones have previ ously been demonstrated as suitable substrates in the modified BartonZard synthesis over vinylic sulfones.36 The modification requires a small excess of strong base to induce the allylic vinyli c sulfone isomerization. S ynthesis of Symmetrical Extended Porphyrins Deprotection of Pyrrole Esters The major advantage of the dihydroisoindole method is that the desired extended porphyrins are prepared under Lindsey conditions. Thi s requires cleavage of the ester from the pyrroleesters obtained from the modified BartonZard reaction. Two methods have been reported for the ester cleavage of the pyrroles. Pyrrole esters prepared from tert butyl isocyanoacetate can be deprotected from TFA at room temperature.59 However pyrroleesters obtained from ethyl isocyanoacetate are heated in ethylene glycol in the presence of excess KOH to provide the unprotected pyrroles.37 The latter method was used to smoothly yield all the precursor pyrroles in good yields and is outlined in Figure 27 Due to instability of the unprotected pyrroles they are not

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56 subjected to purification to analytical standards and are subjected to minimal purification prior to immediate use in a porphyrin synthesis. Figure 2-7 Synthetic scheme for the deprotection of pyrrole esters Reagents and conditions : i) Et hylene glycol, KOH, 170C, 1 h. Synthesis of Tetraaryltetrabenzoporphyrins T etraaryltetrabenzoporphyrins 39a-c were prepared from pyrrole BP and the respective aromatic aldehydes ( 1,3,9) following the reported m et hod for 39 a and as outlined in Figure 2-8.37 Pyrrole BP with one equivalent of aromatic aldehyde ( 1,3,9 ) in DCM in the presence of Lewis acid catalyst yielded the H2Ar4octahydroTBPs which were not isolated and further oxidized to the target TBPs by refluxing in toluene with DDQ in good yields. Figure 2-8 Synthetic scheme for H2Ar4TBPs Reagents and conditions : i) DCM, BF3O(Et)2, DDQ, 4 h, PhMe, DDQ, reflux 1 h

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57 The target TBPs were purified via column chromatography and exhibited good solubility in common organic solvents (DCM, CHCl3, THF). The materials were further purified by multiple precipitations from a good solvent (DCM, CHCl3) into excess methanol under vigorous stirring. Compounds 39a-c w ere characterized by 1H and 13C NMR and mass spectrometry. Synthesis of Tetraaryltetranaphthoporphyrins The synthesis of TN Ps 40a and 40b from the respective naphthopyrroles NP and NP2 followed the reported method for 39a as outlined in Figure 2-9.36 Under Lindsey conditions pyrroles NP and NP2 wer e reacted with one equivalent of aromatic aldehydes ( 1,3 ) gave the target TNPs 40 a and 40b in good yields. In the synthesis of H2Ar4TBP a tetraaryloctahydrotetrabenzoporphyrin could be isolated and then oxidized with DDQ. However in the present synthesis o f H2Ar4TNP s an analogous intermediate was not isolated. The H2Ar4TNPs formed after the addition of DDQ and stirring at room temperature overni ght or a one hour reflux in DCM. The target compounds were purified by chromatography and precipitation into methanol. Compounds 40 a and 40 b were both characterized by 1H and 13C NMR and mass spectrometry and exhibited good solubility in common organic solvents (DCM, CHCl3, THF) Figure 2-9 Synthetic scheme for H2Ar4TNPs Reagents and conditions : i) Dry DCM, BF3 O(Et)2, 1 .5 h, DDQ, reflux 1 h

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58 Synthesis of Tetraryltetraanthroporphyrins Recently two methods have been reported for the preparation of H2Ar4TAPs as outlined in Figure 210 .38, 66 The methods differ in that the one reported by Ono et al from AP uses a solid state high temperature retroDiels Alder reaction to quantitatively yield 42 after intermediate porphyrin 41 has been isolated. Initial a ttempts to reproduce t his method failed leading to incomplete reaction mixtures. However, small milligram quanities of 42 can be obtained from 41 .The method was abandoned due to this difficulty and the unlikely hood of being able to scale the reaction up beyond 1020 milligrams Figure 2-10 Syn thetic scheme for H2Ar4TAP Reagents and conditions : i) DCM, BF3O(Et)2, 1 8 h DDQ, r.t., 1 h ; ii) High vacuum, 290 C, 2 h; iii) DCM, BF3O(Et)2, 1 h DDQ, r.t., 1 h. Alternatively the use of the dihydroisoindole method provides access to the Ar4TAPs at room temperature forming 42 almost instantly after the addition of DDQ to the reaction mixture. However as noted by both literature reports the free base and metal complexes of the TAPs are unstable towards oxygen in the presence of room light. Extreme caution must be taken in the handling and synthesis of these materials by either protecting the material from light or working under inert atmospheres. TAP ( 42)

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59 was prepared from pyrrole AP2 as reported in the literature in a good yield ( Figure 210) The material was purified by column chromatography and then stored under inert atmosphere and further characterized by 1H and 13C NMR and mass spectrometry. Synthesis of 5,15Diaryltetrabenzoporphyrins The interest in 5,15diaryltetrabenzopor phyrins was outlined in the beginning of this chapter. The synthesis of 5,15 diarylporphyrins from meso unsubstituted dipyrromethanes were reported by Treibs et al in 1968.94 Other methodologies were reported by MacDonald and Baldwin et al from meso aryl substituted dipyrromethanes for the preparation of 5, 15diarylporphyrins.9597 Recently the synthesis of 5,15diaryltetrabenzoporphyrins was reported by Filatov et al from meso unsubstituted dipyrromethane 44a and aromatic aldehydes .59 The synthesis is outlined in Figure 2-11 starting from pyrrole-esters 18 a-b with one half equivalent of dimethoxy methane in the p resence of acid catalyst meso unsubstituted dipyrromethanes 43a-b were obtained in good yield from the previously reported method. Figure 2-11 Synthetic scheme for H2Ar2TBPs Reagents and conditions : i) AcOH, TsOH, CH2(OMe)2, 25C, 24 h; ii) Et hylene gl ycol, KOH, 170C, 1 h; iii) DCM TFA, 25 C, 18 h, DDQ, PhMe, DDQ, reflux, 1 h Compounds 44a-b was prepared in a parallel manner to pyrrole BP by heating in ethylene glycol with KOH Similar to BP compound s 44a-b were not subjected t o

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60 extensive purificati on and used immediately in a porphyrins synthesis. The 5,15diaryltetrabenzoporphyrins were obtained by condensing 4 4 a b with one equivalent of aromatic aldehyde ( 1,3,6 ) in the presence of a catalytic amount of TFA followed by the addition of DDQ. The H2Ar2TBPs ( 4 5 a d ) were obtained in good yields after adding the required additional equivalents of DDQ in refluxing toluene to complete the oxidative aromatization. Compounds 4 5 a d were purified by column chromatography and from multiple precipitations into methanol from a good solvent. The overall the solubility of compounds 4 5 b d was good in common organic solvents, except for 4 5 a which exhibited low solubility. The materials were characterized by 1H and 13C NMR and mass spectrometry with 4 5 a b having identic al data to the previous literature reports.37, 59 Synthesis of Extended P latinum P orphyrins The classical conditions for the preparation of platinum (II) porphyrins involves excess molar equivalents of PtCl2 in refluxing benzonitrile (> 190C) with the free base porphyrin. The benzonitrile and PtCl2 form a complex that increases the solubility of the platinum reagent. However despite the increase in solubility the reaction often precedes slowly requiring long reaction times. The addition of the metal to the porphyrin center increases the symmetry of the porphyrin changing the absorption spectra. T herefore the metallation reaction is often followed by UV v is spectroscopy by the disappearance of the Soret and Q band for the free base porphyrin. Thompson et al recently reported Pt TPTBP and prepared the platinum complex from PtCl2 and benzonitrile prior to oxidation with DDQ to form the TBP ring.53 This rep resents one of the few reports for a platinum extended porphyrin report to date. The oxidation step with the precursor platinum porphyrin gave Pt TPTBP in a low yield (30%). The initial attempts to prepare Pt TPTNP ( Pt 40 a ) from PtCl2 and benzonitrile

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61 (200C) were followed by UV Vis spectroscopy (Fi gure 21 2 A). The reaction was followed over five hours with no detectable amounts of Pt 40 a in the UV vis spectrum for the reaction mixture represented by the black, red and blue traces in Figure 21 2 A. Additionally small amounts of Pt 40 a could be detected in the UV Vis spectrum after heating at higher temperatures (>230 C) for prolonged periods of time making these conditions unpractical due to the decomposition of 40a Normalized Absorption 0.0 0.2 0.4 0.6 0.8 1.0 20 minutes 2 hours 5 hours A Wavelength (nm) 300 400 500 600 700 800 900 0.0 0.2 0.4 0.6 0.8 1.0 0 minutes 30 minutes Overnight B Figure 21 2 Platinum metallation reaction for Pt TPTNP ( Pt 40a) followed by UV vis spectroscopy A) H2TPTNP and PtCl2 in PhCN at 200 C followed over 5 h by UV vis spectroscopy. B) H2TPTNP and [Pt4(OAc)8] 2HOAc in PhCN at 180 C followed overnight by UV vis spectroscopy. However, it is known that metal(II) acetates are more reactive than the respective metal(II) halogen species. Platinum(II) acetate is not commercially available and only two reports exist for its preparation but is readily prepared from silver acetate in refluxing acetic acid under and inert atmosphere.98 The reaction of platinum(II) acetate with 40a in benzonitrile (180C) immediately shows the formation of the Pt 40 a after 30

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62 minutes (red trace) from the appearance of a new blue shifted Soret and Q band. The UV vis spectrum of the reaction mixture after heating overnight or five hours (blue trace) shows the complete disappearance of the freebase Soret and Q band (Figure 2-12 B). extended platinum porphyrins at lower temperatures and shorter reaction times in higher yields. The novel reaction conditions have allowed the preparation of platinum complexes for the TNP and TAP systems for the first time, while also providing an improved yield in the synthesis of platinum TBPs over previous literature methods. extended platinum porphyrins (Figure 213 ) were all prepared in an analogous manner to Pt 40 a The materials were subjected to vacuum distillation to remove the high boiling solvent followed by chromatography and multiple precipitations to rem ove small amounts of freebase porphyrins prior to characterization by 1H and 13C NMR and HRMS. Figure 2-13 Synthetic scheme for extended platinum porphyrins Reagents and conditions : i) [Pt4(OAc)8] 2HOAc, PhCN, 180 C under anaerobic conditions

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63 Co nclusions The desired goal of developing 3 series of extended platinum porphyrins was realized. The free base extended porphyrins were prepared following previously reported literature methods. The platinum complexes were prepared from the novel metall ation conditions with platinum acetate developed herein allowing t he platinum complexes for TN P s and TAP to be reported for the first time. Also reported for the first time are platinum complexes for unsymmetrical 5,15diaryl TBPs. The synthesis of extended platinum porphyrins overall are reported in higher yield t han previous literature methods. Access to these new materials has finally allowed for complete characterization followed by investigation of these materials as near IR phosphors in light emitting diode applications Experimental Materials and General Procedures All chemicals used for synthesis were of reagent grade and used without further purification unless noted otherwise. Reactions were carried out under inert atmospheres of argon or ni trogen. Dry solvents were obtained from a solvent purification system or from standard distillation methods unl ess otherwise noted. All glassware was flame or oven dried prior to use unless otherwise noted. NMR spectra were recorded on a Varian Gemini 300, VXR 300, Mercury 300 or Varian Inova 500 spectrometer and chemical shifts are reported in ppm relative to CDCl3 unless otherwise noted Ethyl isocyanoacetate was purchased from Sigma Aldrich and vacuum distilled each time prior to use. Solutions of PhSCl were prepared according to literature methods from N chlorosuccinimide and thiophenol.34 Platinum acetate was prepared from a previously reported method.98 Purifi cation by column chromatography was performed on SiliaFlash silica gel (mesh 230400).

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64 3,5 Di tertbutylbenzaldehyde ( 3 ). The title compound was prepared following a modified literature procedure.80 A solution o f 2 (10.00 g, 48.9 mmol) and NBS (18.00 g 101 mmol) in CCl4 (160 mL) with benzoyl peroxide (80 mg, 0.33 mmol) was refluxed overnight. The formed precipitated was removed by filtration through celite and the solvent removed to yield an oil. The crude mater ial was dissolved in mixture of water (15 mL) and EtOH (15 mL) with hexamethylenetetramine (19.90 g, 142 mmol) and then heated to reflux for 4 hours. The reaction was diluted with a toluene/ether (1:1, 200 mL) mixture and then washed with brine (100 ml x 3). The organic layer was dried over MgSO4 and the solvent removed. The crude material was recrystallized twice from MeOH to give 4.94 g of the title compound (46 %). The material gave identical spectral data to that previously reported in the lit er ature.80 1H NMR (CDCl3 10.01 (s, 1H), 7.73 (m, 3H), 1.36 (t, 18H). 3,5 Di bromobenzaldehyde ( 5 ). The title compound was prepared following a modified literature method.81 Compou nd 4 (3.01 g, 9.6 mmol) in diethyl ether (80 mL) was cooled to 78C followed by the addition of one equivalent of n BuLi dropwise (2.5 M, 3.8 mL). The reaction was stirred for 30 minutes then DMF (740 L, 9.6 mmol) was added dropwise to the reaction and stirred at 78C for one hour. The vessel was then placed in an ice bath and stirred for 30 minutes A 10% HCl solution (100 mL) was added to quench the reaction followed by CHCl3 (150 mL). The organic l ayer was collected and the aqueous layer washed with CHCl3 (80 mL). The organic layers where combined and dried over MgSO4 and the solvent removed. The crude product was purified by column chromatography eluting with 10% EtOAc in hexanes to give 1.93 g of the title compound ( 77 %). Spectral data for the title compound was not reported in the

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65 literature reference.81 1H NMR (CDCl3 9.90 (s, 1H), 7.92 (d, 2H), 7.60 (s, 1H) ; 13C NMR (CDCl3, 75 189.3, 139.7, 139.0, 131.37, 124.1; GC MS [M+H]+ 262.8709, calcd 262.8707. 3,5 D i(4 tertbutylphenyl)benzaldehyde ( 6 ). The title compound was prepared following a modified literature method.77 Compound 5 (1.02 g, 3.9 mmol) and 4tert b utylphenyl boronic acid (1.47 g, 8.3 mmol) were dissolved in toluene (75 mL) and THF (60 mL) with Na2CO3 (1.12 g) and water (9 mL). The solution was purged with argon for 15 minutes followed by the addition of Pd(PPh3)4 (200 mg, 0.2 mmol). The reaction was stirred and purged with argon for 20 minutes and then heated at 100C for 120 hours. The solvent was removed and the crude material loaded on silica eluting with a hexane/DCM mixt ure (70/30). The fractions were combined and the solvent removed. The material was dissolved in minimum of DCM and diluted with MeOH precipitating 865 mg of the title compound (61 %). The title compound is reported in the literature with no experimental or spectral data.99 1H NMR (CDCl3 10.14 (s, 1H), 8.05 (m, 3H), 7.63 (d, 4H), 7.53 (d, 4H) ; 13C NMR (CDCl3, 75 192.7, 151.4, 142.7, 137.6, 137.1, 131.7, 127.1, 127.0, 126.2, 34.8, 31.5; DART MS [M+H]+ 371.2369, calcd 371.2369. 2 Bromo 9,9 dihexylfluorene ( 8 ). The title compound was prepared following a modified literature method.83 A mixture of 7 (2.00 g, 8.2 m mol) and bromohexane (10 mL, 70.8 mmol) with NaOH (2.8 g, 70 mmol) and Bu4NCl in DMSO (20 mL) and water (3 mL) was stirred. The reaction was heated at 80C overnight and then poured into excess ethyl acetate (200 mL). The precipitated NaOH was filtered off and the organic layer washed with 2N HCl solution (100 mL) and brine (100 mL). The organic layer was

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66 collected and dried over MgSO4. The solvent was removed and the crude product purified by column chromatography eluting with hexane to yield 3.14 g of the title compound ( 93 %). The material gave identical spectral data to that previously reported in the literature.83 1H NMR (CDCl3 7.68 7.64 (m, 1H), 7.577.54 (m, 1H), 7.467.43 (m, 2H), 7.33 7.31 (m, 3H), 1.971.90 (m, 4H), 1.151.03 (m, 12H), 0.79 (t, 6H), 0.62 0.58 (m, 4H). 4 (9,9 dihexyl fluorenyl) benzaldehyde ( 9 ). The title compound was prepared following a modified literature method.82 A solution of 8 (1.10 g, 2.7 m mol) and 4formylbenzene boronic acid (438 mg, 2.9 mmol) with Na2CO3 (2.96 g) in THF (20 mL) and water (15 mL) mixture was purged with argon for 30 minutes Then Pd(PPh3)4 (15 mg, 12.9 mol) was added and the solution stirred and purged with argon for 15 minutes prior to heating at 80C overnight. The reaction was cooled to room temperature and then diluted with DCM (100 mL). The organic layer was washed with saturated aqueous NH4Cl solu tion (100 mL) and then dried over MgSO4. The solvent was removed and the crude material purified by column chromatography eluting with 45% hexane in DCM to give 900 mg of the title compound (77 %). The material gave identical spectral data to that previousl y reported in the literature.82 1H NMR (CDCl3, 10.1 (s, 1H), 7.98 (d, 2H), 7.84 (d, 2H), 7.807.77 (m, 1H), 7.577.72 (m, 1H), 7.64 7.61 (m, 1H), 7.59 (m, 1H), 7.35 (m, 3H), 2.01 (m, 4H), 1.05 (m, 12H), 0.75 (t, 6H), 0.68 0.62 (m, 4H). 2 Butyne 1,4 diyl tet raethyl ester phosphoric acid ( 11). The title compound was prepared following a modified literature method.100 In dry pyridine ( 25 mL) compound 10 (5.76 g 66.9 mmol ) unde r an argon atmosphere was cooled to 0C

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67 followed by the dropwise addition o f diethyl chlorophosphate (25 g, 144.9 mmol ). The reaction was stirred for 2 hours at 0C and then diluted with water (125 mL). The mixture was washed with ether (3 x 70 mL) and the combined organic layers dried over Na2SO4. Th e solvent was removed to give 16.0 g of the title compound ( 73 %). The material was pure enough for the subsequent Grignard reaction and gave identical spectral data to that previously reported in the literature.100 1H NMR (CDCl3, 300 MHz): 4.71 (d, 4H), 4.13 (dq, 8H ), 1.34 (t, 12H). 2,3 Dipropyl 1,3 butadiene ( 12). The title compound was prepared following a modified literature method.100 The Grignard reagent was prepared from 1bromopropane (5.15 g, 41.8 mmol) and Mg (1.12 g, 41.8 mmol) turnings in dry THF (60 mL) in a conventional manner. The solution was cooled to 0C followed by the dropwise addition of 11 (5.00 g, 13.9 mmol) in dry THF (30 mL). The reaction was warmed to room temperature and stirred overnight. Water (300 mL) was added to quench the reaction. The formed precipitate was filtered off and then washed with pe ntane (150 mL). The aqueous and organic layers were collected and separated. The aqueous layer was washed with pentane (4 x 80 mL). The organic layers combined and dried over Na2SO4 and the solvent removed under reduced pressure yielding 1.27 g of the titl e compound ( 62 %). The material gave identical spectral data to that previously reported in the literature.100 1H NMR (CDCl3 5.06 (s, 2H), 4.90 (s, 2H), 2.21 (t, 4H), 1.48 (sex, 4H), 0.91 (t, 6H). p Tolyl [ 2 (trimethylsilyl)ethynyl]sulfone ( 15). The title compound was prepared following a modified literature method.84 A solution of AlCl3 (9.4 g, 70.5 mmol) in dry DCM (40 mL) was cannula transferred to TsCl (13.43 g, 70.4 mmol) in DCM (30

PAGE 68

68 mL) and stirred under N2 atmosphere turning orange in color. A separate solution of 14 in DCM (40 mL) w as cooled to 0C in an ice bath. The mixture of AlCl3/TsCl was transferred to the alkyne solution over a period of 10 minutes in small portions. The ice bath was removed and the reaction stirred overnight at room temperature. The mixture was poured into ic e water (400 g) and the organic layer separated and collected. The aqueous layer was washed with DCM (3 x 50 mL). The combined organic layers were dried over MgSO4 and the solvent removed. The crude material was extracted with hot h exanes and upon cooling yielded 10 .01 g of the title compound (67 %). The material gave identical spectral data to that previously reported in the literature.85 1H NMR (CDCl3 7.89 (m, 2H), 7.38 7.35 (m, 2H), 2.46 (s, 3H), 0.21 (s, 9H) Ethynyl p tolyl sulfone ( 16). The title compound was prepared following a modified literature method.86 A solution of 15 (8.01 g, 31.7 mmol) purged with argon in MeOH (65 mL) was cooled to 0C. The cooled solution was treated dropwise with N aF (2.08 g, 49.5 mmol) in water (35 mL) The reaction was stirred for 90 minutes at 0C and then diluted with water (100 mL). The organic layer was separated and collected. The aqueous layer was extracted with ether (3 x 100 mL). The combined organic layer s were washed with water (2 x 100 mL), 10% aqueous NaHCO3 (1 x 100 mL), and brine (1 x 100 mL). The organic layer was dried over MgSO4 and the solvent removed. The crude material was recrystallized from hexanes to yield 5.70 g of the title compound (98 %). The material gave identical spectral data to that previously reported in the literature.86 1H NMR (CDCl3, 75 7.88 (d, 2H), 7.407.37 (d, 2H), 3.45 (s, 1H), 2.47 (s, 3H)

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69 1 Tosyl 1,4 cyclohexadiene (1 7 a ). The title compound was prepared following a modified literature method.37 A thick walled 100 mL vessel with 16 (5.01 g, 27.8 mmol) was cool ed to 78C. Then an excess of 13 ( 20 mL ) was added and the vessel sealed. The reaction was warmed to room temperature and stirred for 48 hours. After removal of excess 1,3 butadiene ( 13) a white oily solid was collected and recrystallized f rom diethyl ether to give 4.82 g of the title compound (74%) The material gave identical spectral data to that previously reported in the literature.37 1H NMR (CDCl3 = 7.757.72 (d, 2H), 7.337.30 (d, 2H), 7.01 (m, 1H), 5.665.63 (m, 2H), 2.93 290 (m, 2H), 2.82 2.79 (m, 2H), 2.42 (s, 3H) 1 Tosyl 4,5 dipropyl 1,4 cyclohexadiene (17 b ). The title compound was prepared following a modified literature method.101 In a thick walled flask with Teflon cap dry toluene (10 mL) and compound 16 (1. 31 g, 7.3 mmol) with 12 ( 1.01 g, 7.3 mmol) under an argon atmosphere was heated at 130C for 48 hours. The reaction was cooled to room temperature and the solvent removed under reduced pressure. The crude material was purified by column chromatography eluting with CHCl3 to give a 1.58 g of a yellow oil (68 %). 1H NMR (CDCl3, 300 MHz 7.76 (d, 2H), 7.33 (d, 2H), 6.96 (m, 1H), 2.86 (m, 2H), 2.74 (m, 2H), 2.42 (s, 3H), 1.96 (m, 4H), 1.32 (m, 2H), 1.30 (m, 2H), 0.87 (t, 3 H) 0.86 (t, 3H) ; 13C NMR (CDCl3, 75 MHz 144.3, 137.9, 136.4, 135.3, 129.9, 128.3, 127.0, 126.4, 34.7, 34.3, 32.0, 28.2, 21.8, 21.4, 14.3; DART MS [M+H]+ 319.1737, calcd 319.1726. 2 Ethoxycarbonyl 4 ,7 dihydro2H isoindole (18 a ). The title compound was prepared following a modified literature method.37 A solution of 17 a (2.5 g 10.7 mmol) in dry THF (25 mL) was added dropwise at 0C to one equivalent of tBuOK (1.44 g

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70 12.8 mmol) and ethyl isocyanoacetate (1.31 g, 11.6 mmol). The reaction was stirred at room temperature for 4 hours. The solvent was removed and the crude material redissolved in DCM (140 mL) The organic layer was washed with water (2 x 80 mL), and brine (1 x 80 mL) and then dried over Na2SO4. T he solvent removed and the crude material recrystallized from hexanes yielding 1.64 g o f light yellow crystals (80%). The material gave identical spectral data to that previously reported in the literature.37 1H NMR (CDCl3, 300 5.82 (m, 2H), 4.31 (q, 2H), 3.463.43 (m, 2H), 3.243.21 (m, 2H), 1.35 (t, 3H) 2 Ethoxycarbonyl 4 ,7 dihydro5,6 dipropyl 2H isoindole (18 b ). The title compound was prepared according to the procedure for 1 8 a A solution of tBuOK (930 mg, 8.3 mmol) in dry THF (30 mL) was cooled to 0 C followed by the addition of ethyl isocyanoacetate (0.9 mL, 8.2 mmol). The solution was stirred for 10 minutes then a solution of 17b (2.4 g, 7.5 mmol) in dry THF (30 mL) was added dropwise. The reaction was warmed to room temperature and stirred for 4 hours. The solvent removed and the crude redissolved in DCM (120 mL). The organic layer was washed with water (2 x 80 mL) and brine (1 x 80 mL) then dried over Na2SO4. The solvent was removed producing an oil that was purified by column chromatography elut ing with CHCl3. The combined fractions were recrystallized from EtOH to giv e 1.09 g of the title compound (52%). 1H NMR (CDCl3, 300 MHz 8.89 (br s, 1H), 6.69 (d, 1H), 4.33 (q, 2H), 3.40 (m, 2H), 3.16 (m, 2H), 2.15 (q, 4H), 1.48 (m, 2H), 1.47 (m, 2 H), 1.36 (t, 3H), 0.9 5 (t, 3 H) 0.94 (t, 3H) ; 13C NMR (CDCl3, 75 MHz 161.7, 128.4, 127.7, 126.6, 120.5, 117.9, 117.2, 60.0, 35.7, 28. 5, 26.9, 22.0, 14.8, 14.5; DART MS 276.1968, calcd 276.1958

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71 2 Chloro1,2,3,4tetrahydro 3 (phenylsulfonyl) n aphthalene ( 20). The title compound was prepared following a modified literature method.36 A solution of PhSCl (18.6 mmol) in dry DCM (40 mL) was added dropwise to 19 (2.0 g, 11.5 mmol) in DCM (30 mL) at 0C. After the addition, the reaction was stirred at room temperature for two hours. The mixture was stored in a freezer over night and the precipitated removed by filtration. The filtrate was cooled to 0C and diluted with DCM (50 mL). In one portion 77% m CPBA ( 9.2 g, 41 mmol) was added and then stirred at room temperature for one hour. A chilled 10% aqueous Na2SO3 (8 0 mL) was added and the mixture stirred at room temperature for one hour The organic layer was washed with 10% aq ueous Na2CO3 (30 mL), 10% aq ueous Na2SO3 (80 mL), and 10% aq ueous Na2CO3 (80 mL). The organic layer collected and dried over K2CO3 and the sol vent removed. T he crude product recrystallized from EtOH to give 3.08 g of the title compound (87%). The material gave identical spectral data to that previously reported in the literature.36 1H NMR (CDCl3 7.57 (m, 5H), 7.227.19 (m, 2H), 7.147.09 (m, 2H), 4.84 (m, 1H), 3.753.70 (m, 1H), 3.513.44 (dd, 1H), 3.513.27 (dd, 1H), 3.203.11 (dd, 1H), 3.07 3.06 (dd, 1H) 4,9 Dihydro 2H benzo[f]isoindole 1 carboxylic acid ethyl ester ( 21). The title compound was prepared following a modified literature method.36 Compound 20 (3.06 g, 10 mmol) in dry THF (10 mL) was added dropwise to a solution of tBuOK (3.1 g, 27. 6 mmol) with ethyl isocyanoacetate (1.13 g, 10 mmol) in dry THF (40 mL) at 0C. The reaction was warmed to room temperature and then refluxed for one hour under an argon atmosphere. The solvent was removed and the crude material dissolved in DCM (120 mL). The organic layer was washed with water (2 x 100 mL) and brine (1 x 100

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72 mL) collec ted and dried over K2CO3. The crude material was recrystallized from EtOH and hexanes to yield 1.53 g (65% ). The material gave identical spectral data to that previously reported in the literature.36 1H NMR (CDCl3= 9.04 (broad s, 1H), 7.33 (m, 1H), 7.24 7.17 (m, 2H), 6.81 (d, 1H), 4.37 (q, 2H), 4.17 (s, 2H), 3.89 (s, 2H), 1.40 (t, 3H) 4a,5,8,8atetrahydronaphthoquione 1,4 dione ( 23). The title compound was prepared following a modified literature method .102 Compound 22 (6.0 g, 55.5 mmol) in AcOH (70 mL) was stirred at room temperature with 13 (12 g, 221.8 mmol) for 24 hours. The mixture was poured into ice water (200 mL) and rapidly stirred. The precipitate was collected and redissolved in warm ether and filtered to remove insoluble material. The solvent was removed to give 3.75 g of the title compound (42%). The material gave identical spectral data to that previously reported in the literature.87 1H NMR (CDCl3, 300 6.67 (s, 2H), 5.70 (m, 2H), 3.273.23 (m, 2H), 2.522.16 (m, 4H). 5,8 Dimethoxy 1,4 dihyronaphthalene ( 24). The title compound was prepared following a modified literature method.102 In acetone (85 mL) 23 (5.4 g, 33.3 mmol) with an excess o f K2CO3 (17.0 g) and dimethyl sulfate (20.0 g, 158.5 mmol) under N2 atmosphere was refluxed for 40 hours. The mixture cooled to room temperature followed by the addition of water (25 mL). The mixture was concentrated and then poured i nto ice cold water ( 500 mL ) with vigorous stirring. The formed precipitate was collected and washed thoroughly with water to remove any residual K2CO3. The crude product was recrystallized from MeOH to give 6.05 g of the title compound (96%). The material gave identical spectr al data to that previously reported in the literature.87 1H NMR (CDCl3 6.65 (s, 2H), 5.89 (s, 2H), 6.70 (s, 6H), 3.28 (s, 4H).

PAGE 73

73 2 Chloro1,2,3,4tetrahydro 5,8 dimethoxy 3 (phenylsulfonyl) naphthalene ( 25). The title compound was prepared following a modified literature method.36 In dry DCM (50 mL) cooled to 0C with 24 (3.5 g, 18.4 mmol) was treated dropwise with PhSCl (23.0 mmol) in DCM (40 mL). After the addition the reaction was stirred at room temperature for 2 hours. The mixture was stored in a freezer overnight and the formed precipitate removed by filtration. The solution was diluted with DCM (50 mL) and cooled to 0C followed by the addition of 77% m CPBA (7.95 g, 46.0 mmol) in one portion. The reaction was warmed to room temperature and stirred for one hour. A solution of chilled 10% aqueous Na2SO3 (100 mL) was added and the mixture stirred for one hour at room temperature. The organic layer was washed with 10% aq ueous Na2CO3 (35 mL), 10% aq ueous Na2SO3 (100 mL), and 10% aq ueous Na2CO3 (100 mL) The organic layer was dried over K2CO3 and the solvent removed. T he crude product was recrystallized from an EtOH and hexane mixture to give 4.30 g of the title compound (64% ). The material gave identical spectral data to that previously reported in the literature.36 1H NMR (CDCl3 7.94 7.90 (m, 2H), 7.67 7.54 (m, 3H), 6.66 (s, 2H), 4.85 4.80 (m, 1H), 3.77 3.67 (overlapping s+s+m, 3H+3H+1H), 3.403.33 (dd, 1H), 3.243.16 (m, 3H). 5,8 Dimethoxy 4,9 d ihydro 2H benzo[f]isoindole 1 carboxylic acid ethyl ester (2 6 ). The title compound was prepared following a modified literature method.36 A solution of tBuOK (1.83 g, 16.3 mmol) in dry THF (60 mL) was cooled to 0C followed by the addition of ethyl isocyanoacetate (2.21 g, 19.6 mmol). To this solution, 25 (3.0 g, 8.1 mmol) in THF (30 mL) was added dropwise. The reaction was warmed to room temperature and then refluxed for one hour. The solvent was removed and the material dissolved in DCM (120 mL). The organic layer was washed with water (2 x 100 mL) and

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74 brine (1 x 100 mL) then dried over K2CO3. T he solvent was removed yielding a red oil that precipitated yellow crystals upon the addition of EtOH The precipitate was fi ltered and washed with hexanes to give 1.73 g of the title compound (70%). The material gave identical spectral data to that previously reported in the literature.36 1H NMR (CDCl3, 300 9.03 (br s, 1H), 6.82 (d, 1H), 6.71 (s, 2H), 4.39 (q, 2H), 4.08 (m, 2H), 4.063.82 (overlapping s+d, 6H+2H), 1.41 (t, 3H). 1,4,4a,9aTetrahydro1,4 e thanoanthracene 9,10dione (2 8 ). The title compound was prepared following a modified literature method.103 A mixture of 1,3cyclohexadiene (7.0 g, 87.3 mmol) and 2 7 (13.8 g, 87.3 mmol) in EtOH (90 mL) was refluxed for 3 hours. The reaction was cooled overnight in a freezer The precipitated crystals were collected a nd the n rec rystallized from boiling EtOH to give 14.05 g of the title compound (67 %). The material gave identical spectral data to that previously reported in the literature.103 1H NMR (CDCl3 7.96 (m, 2H), 7.677.63 (m, 2H), 6.11 (dd, 2H), 3.323.30 (m, 2H), 3.183.17 (m, 2H), 1.771.73 (m, 2H), 1.391.34 (m, 2H) 1, 2,3,4,4a,9,9a,10Octahydro 1,4 e thanoanthracene 9,10diol (2 9 ). The title compound was prepared following a modified literature method.89 A solution of 2 8 (5.7 g, 23.9 mmol) in anhydrous MeOH (150 mL) was cooled to 0C under N2 atmosphere. In one portion NaBH4 (2.5 g, 66.0 mmol) was added and the react ion stirred at 0C f or two hours T he solvent was removed and the crude material purified by column chromatography eluting with a hexane:THF (5:2) solvent mixture removing the first light yellow band. The solvent polarity was then increased to pure THF. The combined fractions afford ed 5.15 g of the title compound (89%) The material gave identical

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75 spectral data to that previously reported in the literature.89 1H NMR (CDCl3 = 7.30 (s, 4H), 6.35 (broad s, 2H), 4.704.67 (m, 2H) 3.03 3.01 (m, 2H), 2.76 (broad s, 2H), 2.21 (broad s, 2H), 1.601.57 (m, 2H), 1.371.34 (m, 2H) 1,4 Dihydro 1,4 ethanoanthracene ( 30). The title compound was prepared following a modified literature method.91 A mixture of TsCl (12.15 g, 63.7 mmol) and 29 (5.15 g, 21.3 mmol) in dry pyridine (40 mL) under N2 atmosphere was stirred for 48 hours at room temperature. The reaction was poured over ice (300 g) and stirred. The pr ecipitated material was collected and dried over MgSO4. The crude product was purified by column chromatography eluting with hexanes yielding 3.25 g of the title compound (74%). The material gave identical spectral data to that previously reported in the l iterature.90 1H NMR (CDCl3, 300 MHz 0 7.77 (AABB 2 H), 7.59 (s, 2H), 7.437.39 (AABB 2H), 6.60 6.57 (m, 2H), 4.06 (m, 2.12), 1.691.56 (m, 4H) 2 Chloro1,2,3,4tetrahydro 3 phenylsulfonyl 1,4 ethanoanthracene ( 31). The title compound was prepared following a modified literature method.66 A solution of 30 (3.25 g, 15.8 mmol) in dry DCM (150 mL) was cooled to 0C in an ice bath. The solution was then treated dropwise with PhSCl (18.9 mmol) in dry DCM (60 mL). The reaction was stirred at room temperature for one hour. The organic layer was washed with 10% aqueous NaHCO3 (80 mL), water (80 mL), and brine (80 mL) The organic layer was collected and dried over Na2SO4.The solvent removed yielding a yellow oil that was diluted with hexanes and EtOH precipitating 4.3 g of white powder that was collected and dried The crude material was dissolved in DCM (100 mL) and cooled to 0C fo llowed by the addition of 77% m CPBA (6.8 g, 39.4 mmol) in one portion. The reaction was warmed to room temperat ure an d stirred overnight. The p recipitate was

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76 filtered off and the solvent removed. The m aterial was recrystallized from hex anes/ EtOH to give 3.53 g of the title compound (59%). The material gave identical spectral data to that previously reported in the literature.66 1H NMR (CDCl3 7.78 (m, 4H), 7.68 (s, 1H), 7.62 7.56 (m, 2H), 7.517.43 (m, 4H), 4.354.32 (m, 1H), 3.853.83 (m, 1H), 3.63 3.60 (m, 1H), 3.413.38 (m, 1H), 2.43 2.33 (m, 1H), 2.081.98 (m, 1H), 1.671.43 (m, 2H) 4,11Dihydro 4,11ethano2H napth[2, 3f]isoindole 1 carboxylic acid ethyl ester ( 32 ) The title compound was prepared following a modified literature method.66 A solution of dry THF (40 mL) and 31 (2.63 g, 6.9 mmol) was added dropwise at 0C to tBuOK (1.85 g, 16.5 mmol) and ethyl isocyanoacetate (93 mg, 8.2 mmol). After the addition the reaction was warmed to room temperature and stirred overnight. The organic layer was washed with water (2 x 100 mL) and brine (1 x 100 mL) collected and dri ed over Na2SO4. The solvent was removed yielding an oil. The addition of hexane and EtOH precipitated the title compound as a white powder to give 805 mg (37%). The material gave identical spectral data to that previously reported in the literature.66 1H NMR (CDCl3 7.38 (m, 2H), 6.07 (s, 1H), 4.90 (s, 1H), 4.394.34 (m, 3H), 1.81 (m, 4H), 1.441.40 (m, 3H) 1,4 Epoxy 1,4 dihydronaphthalene ( 33 ). The title compound was prepared following a modified literature method.92 In dry THF (120 mL) anthranilic acid (9.5 g, 69.3 mmol) was cooled to 0C followed by the addition of isoamyl nitrite (20 mL) dropwise. The mixture was then warmed to room temperature and stirred for one hour. The yellow pr ecipitate was collected by filtration (Caution: explosion hazard do not allow

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77 precipitate to dry or come in contact with metal) and transferred to a flask with dry THF (120 mL), furan (4.40 g, 64.6 mmol), and propylene oxide (6 mL). The mixture was slowly warmed to 70C under a N2 atmosphere until the precipitate disappeared with adequate venting. The solution was then heated to reflux for 20 minutes. The solvent was removed under reduced pressure and the crude product purified by column chromatography elut ing with 10% ethyl acetate in hexanes. The material from the combined fractions was recrystallized from hexanes to give 4.60 g of the title compound (49%). The material gave identical spectral data to that previously reported in the literature.93 1H NMR (CDCl37.23 (dd, 2H), 7.01 (s, 2H), 6.95 (dd, 2H), 5.70 (s, 2H). 9,10Epoxy 1,4,4a,9,9a,10hexahydroanthracene ( 34). The title compound was prepared following a modified literature method.38 A 60 mL thick walled flask with Teflon screw cap with 33 (5.05 g, 35.0 mmol) and NaHCO3 (2.5 g, 29.75 mmol ) dissolved in pyridine (20 mL) freshly distilled over NaOH. To this solution 3sulfolene (4.55 g, 38.5 mmol) was added in seven equal portions. The reaction was heated at 120C for 10 hours after each addition of 3sulfolene. The reaction was carefully vented prior to each new addition and heating cycle. The mixture was filtered through celite and the solvent removed. The crude mat erial was dissolved in DCM and passed through a short (4) column of silica gel The solvent was removed to give yellow oil that precipitated crystals upon addition of MeOH. The product was collected and dried to give 4.89 g of the title compound (70%). Th e material gave identical spectral data to that previously reported in the literature.38 1H NMR (CDCl37.23 (AABB, 2H),

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78 7.13 (AABB, 2H), 5.95 (m, 2H), 5.00 (s, 2H), 2.522.46 (m, 2H), 2.09 2.01 (m, 2H), 1.951.89 (m, 2H). 1,4 Dihydroanthracene (3 5 ). The title compound was prepared following a modified literature method.38 Compound 3 4 (4.89 g, 24.7 mmol) dissolved in a mixture of EtOH (100 mL) and HCl (10 mL) heated to reflux for 24 hours under an argon atmosphere. After cooling in an ice bath a crystalline precipitate formed and was collected The material was recrystallized from MeOH and dried to give 3.64 g of the title compound (82%). The material gave identical spectral data to that previously reported in the literature.38 1H NMR (CDCl3 7.77 (AABB, 2H), 7.64 (s, 2H), 7.42 (AABB, 2H), 6.06 (m, 2H), 3.60 (s, 4H). 2 Chloro3 (phenylsulfonyl) 1,2,3,4 tetrahydroanthracene (36 ). The title compound was prepared following a modified literature method.38 In dry DCM (80 mL) 35 (2.5 g, 13.9 mmol) was cooled to 78C and treated dropwise with a solution of PhSCl (16.5 mmol) in dry DCM (80 mL). After the a ddition the reaction mixture was stirred for 4 hours at room temperature and then placed in a freezer for 2 hours. The precipitated w as removed. The reaction mixture was then cooled to 0C followed by the addition of 77% m CPBA (7.18 g, 41.6 mmol). The reaction was warmed to room temperature and stirred under a N2 atmosphere for 48 hours. T he reaction was diluted with aqueous 10% Na2SO3 (50 mL) and stirred for 30 minutes. The organic layer was washed with aqueous 10% Na2CO3 (80 mL), aqueous10% Na2SO3 (80 mL), and aqueous 10% Na2CO3 (80 mL) then dried over K2CO3. The solvent was removed under reduced pressure and the crude material recrystallized from MeOH yielding 3.55 g of the title compound (72%). The material gave identical spectral data to that previousl y

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79 reported in the literature.38 1H NMR (CDCl37.99 (m, 2H), 7.77 (m, 2H), 7.70 (m, 1H), 7.64 (s, 1H), 7.61 (m, 2H), 7.46 (m, 2H), 4.97 (m, 1H), 3.79 (m, 1H), 3.58 (d d, 1H), 3.45 (dd, 1H), 3.34 (dd, 1H), 3.28 (dd, 1H). 2 (Phenylsulfonyl) 1,2dihydroanthracene ( 3 7 ). The title compound was prepared following a modified literature method.38 In dr y DCM (30 mL) compound 3 6 (3.54 g, 9.91 mmol) was treated dropwise with one equivalent of DBU (1.51 g, 9.91 mmol). After the addition the reaction mixture was stirred at room temperature for one hour then diluted with water (30 mL) The layers were separated and the aqueous layer was washed with DCM (3 x 50 mL). The organic layers combined and dried over Na2SO4 and the solvent removed under reduced pressure. The crude material was recrystallized from MeOH yielding 2.80 g of the title compound (89%). The ma terial gave identical spectral data to that previously reported in the literature.38 1H NMR (CDCl3 7.75 (m, 2H), 7.66 (m, 2H), 7.437.37 (m, 3H), 7.34 (m, 1H), 7.297.20 (m, overlap with solvent, 3H), 6.80 (d, 1H), 6.13 (dd, 1H), 4.13 (m, 1H), 3.61 (dd, 1H), 3.40 (dd, 1H). Ethyl 4,11dihydro 2H naphtho[2,3 f ]isoindole 1 carboxylate (38 ). The title compound was prepared following a modified literature method.38 In dry THF (30 mL) tBuOK (1.4 g, 12.5 mmol) was stirred at 0C followed by the addition of ethyl isocy anoacetate (988 mg, 8.73 mmol) and stirred at room temperature. Compound 3 7 (2.80 g, 8.73 mmol) in dry THF (30 mL) was added dropwise at 0C. The mixture was warmed to room temperature and stirred overnight. The solvent was removed and the crude material redi ssolved in DCM (120 mL). The organic layer was washed with water (2 x 100 mL) and brine (1 x 100 mL) and dried over K2CO3. The solvent removed under

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80 reduced pressure and the crude material purified by column chromatography eluting with DCM/Hexanes (80:20). The combined fractions recrystallized from MeOH yielding 1.163 g of the title compound (46%). The material gave identical spectral data to that previously reported in the literature.38 1H NMR (CDCl3, 300 MHz) 8.96 (br s, 1H), 7.80 (s overlapped, 1H), 7.76 (m, 2H), 7.74 (s overlapped, 1H), 7.44 (m, 2H), 6.86 (d, 1H), 4.43 (q overlapped, 2H), 4.39 (s, 2H), 4.06 (s, 2H), 1.44 (t, 3H). 4,7 dihydr o 2H isoindole (BP ) A suspension o f 18 a (600 mg, 3.1 mmol) in ethylene glycol (20 mL) with KOH (880 mg, 15.7 mmol) was thoroughly purged with argon. The mixture was heated to 170C for 1 hour. The reaction was immediately cooled in an ice bath and diluted with DCM (100 mL). The organic layer was washed with water (2 x50 mL) and brine (1 x 50 mL) collected and dried over Na2SO4. The solvent was removed producing a dark amber colored oil that was vacuum dried to a consistent weight to give 287 mg of the ti tle compound (77%). TLC analysi s ver ified that no starting material was present. The title compound was immediately used in a porphyrin synthesis without further purification due its instability. ESI TOF [M+H]+ and [2M+H]+ 120.0813, 239.1545, calcd 120.0808, 239.1543. 4,9 Dihydro 2H benzo[f] isoindole (NP ). The title compound was prepared from 21 following the procedure used for BP (86 %). APCI MS [M+H]+ 170.0961, calcd 170.0964. 5,8 D imethoxy 4,9 dihydro2H benzo[f]isoindole (NP2 ). The title compound was prepared from 26 following the procedure used for BP (61%). ESI TOF [M+H]+ and [M+Na]+ 230.1176, 252.0990, calcd 230.1176, 252.0990.

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81 4,11Dihydro 4,11ethano2H napth[2,3f]isoindole ( AP ). The title compound was prepared from 32 following the procedure used for BP (87%). ESI TOF m/z 246.1275, calcd 246.1277. 4,11Dihydro 2H naphtho[2,3 f]isoindole ( AP2 ). The title compound was prepared from 38 following the procedure used for BP (82%). CI MS [M]+ and [M+H]+ 219.1054, 220.1132 calcd 219.1048, 220.1126. T e traphenyltetrabenzoporphyrin ( 39a). The title compound was prepared following a modified literature method.37 A solution of BP (287 mg, 2.4 mmol) and 1 (255 mg, 2.4 mmol) in dry DCM (250 mL) was stirred under an argon atmosphere protected from light. After the addition BF3O(Et)2 (60 mg, 0.4 mmol) the reaction was stirred for 3 hours at room temperature. In one portion DDQ (603 mg, 2.7 mmol) was added and the reaction stirred for one hour. The solvent was removed and the material redissolved in toluene (80 mL) with DDQ (655 mg, 2.9 mmol) heated to reflux under argon for one hour. The solvent was removed and the crude material dissolved in DCM (120 mL). The organic layer was washed with aqueous 10% Na2SO3 (2 x 100 mL), water (2 x 100 mL) and brine (1 x 100 mL) collected and dried over Na2SO4. The crude material was loaded on silica and purified by column chr omatography eluting with 2% MeOH in DCM. The first bright green band was collected and the solvent removed. The material was dissolved in a minimal amount of boiling CHCl3 vigorously stirred and diluted with MeOH (10x volume) precipitating small green crys talline flakes. The precipitate was collected and repeat edly washed with MeOH yielding 140 mg of t he title compound (2 9%). The NMR spectra were recorded on a Varian Inova 500 MHz, operating at 500 MHz for 1H, 125 MHz for 13C, and 50 MHz for 15N. The probe was an

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82 indirect detection triple resonance probe, with z axis gradients. The proton spectrum at 25C displayed a broad signal for the protons of the orthophenylene moiety, due to the exchange of the NH protons.104 This broad signal was resolved at 50C into two AABB patterns, while the NH pr otons displayed a sharp signal at 1.34 ppm, as the exchange became slower. Because of the limited solubility of H2TPTBP in the NMR solvent, 13C chemical shifts were measured by indirect detection, in a gHMBC spectrum. The material gave identical spectral data to that previously reported in the literature.104 1H NMR (CDCl3 4H), 7.34 (AABB, 4H), 7.18 (AABB, 4H), 6.98 (AABB, 4H), 1.34 (s, 2H); 13C NMR (CDCl3 133.7, 134.7, 140.1, 141.9; ESI TOF [M+H]+ 815.3169, calcd 815.3169. Tetra(3,5di tertbut ylphenyl)tetrabenzoporphyrin ( 39b). The title compound ( H2Ar4TBP) was prepared from a solution of BP (296 mg, 2.5 mmol) and 3 (542 mg, 2.5 mmol) in dry DCM (250 mL) according to the procedure for 39 a The crude product was purified by column chromatography eluting with DCM collecting the second large green band. The solvent was removed and the material dissolved in boiling methanol after cooling 158 mg of t he title c ompound was collected by filtration (20%). 1H NMR ( pyridined5, 5 8.48 (s, 8H), 8.25 (s, 4H), 7.66 (d, 8H), 7.47 (m, 8H), 1.59 (s, 72H) ; 13C NMR ( pyridined5, 125 152.6, 138.4, 130.2, 126.4, 125.5, 122.7, 118.0, 35.7, 32.0 ; MALDI MS [M]+ and [M+H]+ 1262.8042, 1263.8179, calcd 1262.8099, 1263.8177. Tetra(4 (9,9 dihexyl fluorenyl ) phenyl)tetrabenzoporphyrin ( 39c). The title compound ( H2ArF4TBP) was prepared from a solution of BP (143 mg, 1.2 mmol) and 9

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83 (520 mg, 1.2 mmol) in dry DCM (150 mL) according to the procedure for 39 a The crude product was purified by column chromatography eluting with 20% EtOAc in hexane collecting the first large green band. The solvent was removed and the material precipit ated from DCM and MeOH to give 1 10 mg of the title compound (17%).1H NMR ( pyridined5, 500 MHz 8.67 (d, 8H), 8.50 (d, 8H), 8.24 (d, 4H), 8.19(d, 4H), 8.05 (d, 4H), 7.85 (d, 8H), 7.70 (d, 4H), 7.55 (m, 8H), 7.42 (m, 8H), 2.44 (dd, 8H), 2.35 (dd, 8H), 1.28 (m, 16H), 1.23 (m, 32H), 1.13 (m 16H), 0.88 (t, 24H) ; 13C NMR ( pyridined5, 125 MHz 153.0, 152.3, 143.2, 142.2, 141.9, 141.8, 140.5, 138.0, 136.2, 128.4,128.2, 128.0, 127.5, 127.0, 125.4, 124.1, 122.8, 121.2, 120.9, 116.8, 56.5, 41.1, 32.1, 30.4, 24.9, 23.1, 14.4; MALDI MS [M]+ and [M+H]+ 2143.3074, 2144.3104, calcd 2143.3107, 2144.3185. Tetraphenyltetranap hthoporphyrin ( 40a ) The title compound was prepared following a modified literature method.3 6 In dry DCM (250 mL), NP (430 mg, 2.54 mmol) and 1 (270 mg, 2.54 mmol) was stirred under argon atmosphere and protected from light After the addition of BF3O(Et)2 (72 mg, 0.5 mmol) the reaction was stirred at room temperature for 90 minutes. In one por tion DDQ (2.88 g, 12.7 mmol) was added and the reaction brought to reflux for one hour. The organic layer was washed with 10% aqueous Na2SO3 (2 x 100 mL), and water (2 x 100 mL) and dried over K2CO3. The solvent removed and the crude material loaded on neutral silica eluting with DCM collecting the first major green band. The material was redissolved in boiling CHCl3 and diluted with excess MeOH precipitating fine green crystals to give 116 mg of the title compound (20%). The material gave identical spectral data to that previously reported

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84 in the literature.36 1H NMR (CDCl3TFA 8.60 (m, 8H), 8.08 7.97 (m, 20H), 7.757.72 (m, 8H), 7.537.50 (m, 8H), 2.49 (s, 4H) 1,4,10,13,19,22,28,31Octamethoxy 7,16,25,34tetrakis(3,5di tertbutylphenyl) tetr anaphthoporphyrin ( 40 b ). The title compound (H2Ar4TNP(OMe)8) ( 4 0 b ) was prepared according to the procedure for 40a from a solution of NP2 (242 mg, 1.0 mmol) and 3 (230 m g, 1.0 mmol) in dry DCM (18 0 mL) The solvent was removed and the crude material purified by chromatography eluting with DCM followed by multiple precipitati ons from DCM and MeOH to give 72 mg of the title compound (16 %). 1H NMR ( pyridine d5, 5 8.66 (s, 8H), 8.49 (s, 8H), 8.37 (s, 4H), 6.86 (d, 8H), 4.03 (s, 24H), 1.60 (s, 72H) ; 13C NMR ( pyridined5, 125 MHz) 152.9, 151.1, 142.8, 136.1, 128.5, 125.3, 122.6, 120.2, 119.5, 116.8, 103.5, 55.7, 35.4, 31.8 ; MALDI TOF MS [M]+ 1703.9685, calcd 1703.9603. 8,19,30,41tetrakis(3,5 di butylphenyl) 6,10,17,22,27,32,39,43octahydro 6,43:10,17:21,28:32,39tetr aethano 45H,47H tetraanthra porphyrin ( 41) The title compound was prepared following a modified literature method.66 A mixture of 3 (200 mg, 0.9 mmol) with AP (225 mg, 0.9 mmol) in dry DCM (170 mL) was stirred protected from light under an argon atmosphere. After the addition of BF3O(Et)2 (58 mg, 0.4 mmol) the reaction was stirred at r oom temperature for 18 hours. In one portion DDQ (1.08 g, 4.75 mmol) was added and the mixture stirred for 90 minutes. The organic layer was washed with 10% aqueous Na2SO3 ( 2 x 100 mL), water (1 x 100 mL), and brine (1 x 100 mL) collected and dried over Na2SO4. The solvent removed and the crude material passed through a silica column eluting with DCM. The combined fractions dissolved in warm THF (25 mL) and diluted with MeOH (250 mL). The solution became

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85 turbid and was placed in the refrigerator overnight. The formed precipitate was filtered and washed repeatedly with MeOH. The precipitate was collected and dried to give 209 mg of the title compound (51%). The material gave identical spectral data to that previously reported in the literature.66 1H NMR (CDCl3 7.26 (mixture of isomers, overlap with solvent, 36H), 3.95 (m, 8H), 1.831.63 (m, bridge + t Bu, 88H) Tetra(3,5di tertbut ylphenyl)tetraanthroporphyrin ( 42). The title compound was prepared following a modified literature method.38 The so lvents used in this procedure w ere thoroughly purged with argon or subjected to freeze pump thaw cycles due to the oxygen sensitivity of 4 2 A mixture of AP2 (150 mg, 0.67 mmol) and 3 (149 mg, 0.68 mmol) in dry DCM (100 mL) was stirred under an argon atmosphere protected from light. The reaction was stirred for one hour after the addition of BF3 OEt2 (20 L). A solution of DDQ (232 mg, 1.0 mmol) in toluene (4 mL) was subjected to freeze pump thaw cycles in a schlenk flask prior to addition. After the addition the reaction was stirred for one hour at room temperature and then quenched by the addition of aqueous 10% Na2SO3 (100 mL). The organic layer was separated and washed with aqueous 10% Na2SO3 (100 mL), aqueous 10% Na2CO3 (100 mL), and brine (100 mL). The organic layer was dried over Na2SO4 and the solvent removed under reduced pressure. The material was purified by column chromatography eluting wit h DCM. The combined fractions w ere concentrated and the material precipit ated by the addition of excess MeOH. The precipitate was collected to give 95 mg of the title compound (33%). 1H NMR ( pyridined5, 5 8.67 (s, 8H), 8.65 (s, 8H), 8.58 (s, 4H), 8.37 (s, 8H), 8.15 (s, 8H), 7.52 (t, 8H), 1.67 (s, 72H) ; 13C NMR ( pyridined5, 125 32.2, 35.9,

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86 116.3, 123.2, 125.7, 126.1, 128.2, 129.1, 129.6, 130.8, 132.8, 136.7; MALDI TOF MS [M]+ 1663.9403, calcd 1663.9384. Bis(3 ethoxycarbonyl 4,7 dihydro 2H isoindolyl)metha ne (43a ). The title compound was prepared following a modified literature method.59 A solution of 18 a (1.606 g, 8.4 mmol) and dimethoxy methane (319 mg, 4.2 mmol) in AcOH (130 mL) and TsOH (165 mg, 0.9 mmol) under N2 atmosphere was stirred for 24 hours. The reaction was poured into ice water (200 mL) and vigorously stirred. The precipitated material was collected and washed with water (1x 100 mL) and cold MeOH (2 x 50 mL). The title compound was dried under vacuum to give 1.38 g (85%). The material g ave identical spectral data to that previously reported in the literature.59 1H NMR (CDCl3d6DMSO 11.19 (br s, 2H), 5.77 (m, 4H), 4.17 (q, 4H), 3.71 (s, 2H), 3.24 (m, 4H overlap with solvent), 3.02 (m, 4H), 1.27 (t, 6H). B is(3 ethoxycarbonyl 4,7 dihydro 5,6 dipropyl 2H isoindolyl)metha ne (43b ). The title compound was prepared from a solution of 18 b (920 mg, 3.3 mmol), dimethoxy methane (127 mg, 1.7 mmol), TsOH (75 mg, 0.4 mmol) in 75 mL of AcOH following the procedure for 4 3 a The crude material was reprecipi tated from boiling CHCl3 and excess MeOH to give 470 mg of the title compound (50 %). 1H NMR (CDCl3, 300 MHz ): 9.43 (s, 2H), 4.26 (q, 3H), 3.88 (s, 2H), 3.37 (m, 4H), 3.51 (m, 4H), 2.16 (m, 8H), 1.46 (m, 8H), 1.30 (t, 6H), 0.95 (t, 3H), 0.94 (t, 3H) ; 13C NMR (CDCl3, 75 MHz 162.2, 128.7, 128.4, 127.3, 117.5, 116.0, 60.0, 35.7, 28.9, 26.6, 23.3, 22.0, 14. 7, 14.6; ESI MS [M+H]+ 563.3851, calcd 563.3843. Bis(4,7 d ihydro 2H isoindolyl)methane (4 4 a ). The title compound was prepared according to the procedure used for BP A suspension of 43 a (650 mg, 1.65

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87 mmol) in ethylene glycol (40 mL) with KOH (925 mg, 16.5 mmol) was thoroughly purged with argon and heated to 170C for 1 hour. The isolated material was dried under vacuum to a consistent weight to give 351 mg of the title compound (84%). Due to instability 44a was used immediately and not subjected to fur ther purification DART MS [M+H]+ 251.1563, calcd 251.1543. Bis(4,7 d ihydro 5,6 dipropyl 2H isoindolyl)methane (44 b ). The title compound was prepared according to the procedure used for 44a from 43b (450 mg, 0.8 mmol) to give 255 mg of the title compound (76%) ESI MS [M+H]+ 419.3429, calcd 419.3421. 5,15Diphenyltetrabenzoporphyrin (45 a). The title compound was prepared following a modified literature method.59 In dry DCM (200 mL) 44 a (352 mg, 1.4 mmol) and 1 (149 mg, 1.4 mmol) were stirred protected from light under an argon atmosphere. After the addition of TFA (30 mg, 0.3 mmol) the reaction was stirred for 18 hours at room temperature. DDQ (478 mg, 2.1 mmol) was added in one portion and the reaction stirred for on e hour. The solvent was removed under reduced pressure. The material was redissolved in toluene (120 mL) with DDQ (634 mg, 2.8 mmol) and refluxed for 30 minutes. The solvent was removed and the crude material dissolved in DCM (120 mL). The organic layer was washed with aqueous 10% Na2SO3 (2 x 100 mL), water (2 x 100 mL), and brine (1 x 100 mL). The organic layer was collected and dried over Na2SO4. The material loaded on silica and purified by column chromatography eluting with DCM. The combined fractions were dissolved in a minimal amount of boiling CHCl3 and precipitated by the slow addition of MeOH ( excess) under vigorous stirring. The precipitate was collected and repeatedly washed with MeOH to give 178 mg of the title

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88 compound (38%). The material gave identical spectral data to that previously reported in the literature.59 1H NMR (CDCl3TFA 10.98 (s, 2H), 9.38 (d, 4H), 8.44 (m, 4H), 8.17 (ddd, 4H), 8.12 (m, 2H), 8.04 (m, 4H), 7.83 (ddd, 4H), 7.58 (d, 4H), 3.51 (br s, 4H). 5,15Di(3,5 di tertbut ylphenyl) tetrabenzoporphyrin (45 b). The title compound was prepared following a modified literature method.59 Following the procedure for 45 a the title compound was prepared from a solution of 44 a (309 mg, 1.2 mmol) and 3 (269 mg, 1.2 mmol) in dry DCM ( 180 mL). The crude material was purified by column chromatography eluting with DCM. Then precipitated by dissolving in a minimum amount of boiling CHCl3 diluting with MeOH to give 158 mg of the title compound after filtration and repeated washing with MeOH (29 %). The material gave identical spectral data to that previously reported in the literature.59 1H NMR (CD2Cl2, 11.15 (s, 2H), 9.73 (d, 4H), 8.17 (m, 4H), 8.12 (m + d overlapped, 6H), 7.77 (m, 4H), 7.53 (m, 4H), 1.56 (s, 36H), 1.25 (br s, 2H). 5,15Di( ( 3,5 di tertbut ylphenyl ) phenyl)tetrabenzoporphyrin (45 c ). The title compound was prepared from a solution of 4 4 a (369 mg, 1.5 mmol) and 6 (546 mg, 1.5 mmol) in dry DCM (180 mL) following the procedure used for 45a The material w as purified by column chromatography on silicagel eluting with DCM. The fractions were concentrated and the title compound precipitated from the addition of excess MeOH to give 220 mg (25 %). 1H NMR ( pyridined5, 5 = 1.44 (s, 36H), 7.67 (d, 8H), 7.94 (t, 4H), 8.14 (d, 8H), 8.21 (t, 4H), 8.29 (d, 4H), 8.90 (s, 2H), 8.92 (s, 4H), 10.00 (d, 4H), 11.56 (s, 2H); 13C NMR ( pyridined5, 125 31.8, 35.0, 94.3, 117.7, 122.4,

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89 125.9, 126.8, 128.0, 128.3, 130.8, 138.0, 138.5, 140.3, 143.5, 150.5,151.9 ; DART MS [M+H]+ 1191.6296, calcd 1191.6299. 5,15Di(3,5 di tertbut ylphenyl)o ctapropyltetrabenzoporphyrin (45 d ). The title compound was from a solution of 44 b (255 mg, 0.6 mmol) and 3 (133 mg, 0.6 mmol) in dry DC M (110 mL) The material was purified by column chromatography on silica gel eluting with 2% MeOH in DCM to give 68 mg of the title compound following the procedure for 45 a (18 %). 1H NMR ( pyridined5, 5 00 MHz 11.66 (s, 2H), 9.90 (s, 4H), 8.45 (s, 4H), 8.42 (s, 2H), 7.75 (s, 4H), 3.26 (t, 8H), 3.08 (t, 8H), 2.07 (sex, 8H), 1.93 (sex, 8H), 1.72 (s, 36H), 1.25 (t, 12H), 1.24 (t, 12H) ; 13C NMR ( pyridined5, 125 MHz 152.8, 141.0, 140.7, 140.2, 138.6, 136.6, 128.0, 126.2, 123.2, 122.1, 117.9, 93.6, 36.6, 36.4, 35.8, 32.2, 25.5, 25.2, 14.8, 14.7 ; DART MS [M+H]+ 1223.8763, calcd 1223.8803. Platinum Tetraphenyltetrabenzoporphyrin ( Pt 39a ). A solution of 39a (49 mg, and platinum acetate (83 mg, 6 thoroughly purged with argon. The reaction was then submerged in a preheated oil bath at 200 C and refluxed until the Q band of 39 a disappeared from the UV Vis spectrum. The solvent was removed under reduced pressure and the crude material dissolved in DCM and filtered through a plug of Celite. The material was then loaded on silica and purified via column chromatography eluting with 30% DCM in Hexanes yielding 45 mg of the title compound (74%). 1H NMR ( pyridined5, 5 00 8.35 (d, 8H), 7.96 (t, 4H), 7.92 (t, 8H), 7.42 (m, 8H), 7.37 (m, 8H) ; 13C NMR ( pyridined5, 125 142.1, 138.2, 136.7, 134.2, 129.9, 129.9, 126.3, 124.8; ESI TOF m/z 1006.2549, calcd 1006.2562.

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90 Platinum Tetra(3,5 di tertbut ylphenyl )tetrabenzoporphyrin (Pt 39b). The title compound was prepared from 39 b 30 mL) using the procedure for Pt 39 a The crude material was purified via column chromatography eluting wi th 30% DCM in hexanes yielding 32 mg of the title compound (35%). 1H NMR ( pyridined5, 5 8.31 (s, 8H), 8.17 (s, 8H), 7.51 (m, 8H), 7.44 (m, 8H), 1.46 (s, 72H) ; 13C NMR ( pyridined5, 125 153.3, 138.9, 136.6, 129.0, 126.4, 125.6, 122. 9, 120.5, 35.6, 32.0; DART MS [M+H]+ 1457.7687, calcd 1457.7694. Platinum Tetra(4 (9,9 dihexyl fluorenyl) phenyl)tetrabenzoporphyrin ( Pt 39c). The title compound was prepared from 39c acetate (49 mg, 35.4 le (25 mL) using the procedure for Pt 39 a The crude material was purified by chromatography eluting with 20% hexanes in DCM. The fractions combined and concentrated in DCM then diluted with excess MeOH to give 78 mg of the title compound (94%). 1H NMR ( py ridine d5, 5 8.50 (m, 12H), 8.21 (d, 4H), 8.18 (d, 4H), 8.04 (d, 4H), 7.69 ( d 8H), 7.66 (d, 4H), 7.53 (t, 8H), 7.30 (m, 8H), 2.37 (t 4 H), 2.27 ( t, 4 H), 1.14 ( m, 16 H), 1.11 ( q, 16 H), 0.99 ( m, 16 H), 0.95 (m, 16H ), 0.77 (t, 24H) ; 13C NMR ( pyridined5, 125 152.9, 152.0, 142.8, 142.2, 141.7, 141.2, 140.0, 138.5, 137.2, 135.1, 128.7, 128.4, 127.9, 127.4, 126.6, 125.1, 124.0, 121.4, 121.0, 119.3, 41.0, 32.1, 30.4, 24.8, 23.2, 14.5; MALDI TOF MS [M+H]+ 2338.2735, calcd 2338.2709. Platinum Tetraphenyltet ranaphthoporphyrin ( Pt 4 0 a ). The title compound was prepared from 4 0 a Pt 39 a heating at 180C The

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91 crude material was passed a column of n eutral silica eluting with DCM:THF (9:1). The first dark green band was collected and the solvent removed. The material was precipitated from DCM and acetonitrile. The precipitate was collected and washed repeatedly with cold MeOH yielding 70 mg of the tit le compound (53%). The 1H and gHMBC spectrum of compound Pt TPTNP were taken on a Varian Inova 500 NMR spectrometer, equipped with a 5 mm indirect detection probe and with z axis gradients, and operating at 500 MHz for 1H and 125 MHz for 13C. The chemical shifts were referenced to the residual solvent signals, 7.22 ppm in 1H and 123.9 in 13C. Because of the limited solubility of Pt TPTNP in the NMR solvent, 13C chemical shifts were measured by indirect detection, in a gHMBC spectrum. 1H NMR (pyridine d5, 500 MHz) 8.44 (m, 8H), 8.228.14 (m, 4H), 8.108.03 (m, 8H), 7.93 (s, 8H), 7.907.84 (m, 8H), 7.61 (8H, overlap with solvent); 13C NMR (pyridine d5 134.2, 131.6, 130.5, 130.0, 129.7, 126.7, 124.1, 117.9; ESI TOF m/z 1206.3188, calcd 1206.3157. Platinum 1,4,10,13,19,22,28,31O ctamethoxy 7,16,25,34tetrakis(3,5di tertbutylphenyl)tetranaphthoporphyrin (Pt 4 0 b ). The title compound was prepared from 4 0 b le (30 mL) using the procedure for Pt 39a. The crude material was passed through a column of neutral silica eluting with DCM. The first dark green band was collected and the solvent removed. The material was precipitated from warm CHCl3 and MeOH. The preci pitate was collected and washed repeatedly with cold MeOH yielding 110 mg of the title compound ( 85 %). 1H NMR ( pyridined5, 5 8.56 (s, 8H), 8.30 (s, 8H), 8.29 (s, 4H), 6.82 (d, 8H), 3.93 (s, 24H), 1.46 (s, 72H) ; 13C NMR ( pyridine d5, 125

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92 153.6, 151.1, 136.4, 127.5, 125.0, 123.5, 119.7, 119.5, 103.3, 55.8, 35.7, 32.0; MALDI TOF MS [M]+ 1896.9161, calcd 1896. 9090. Platinum Tetra(3,5 di tertbut ylphe nyl)tetraanthroporphyrin (Pt 42) Due to the sensitivity with oxygen in the presence of room light for the title compound and 4 2 all manipulations were preformed under inert atmospheres and flask protected from li ght with foil. A schlenk flask charged with benzonitrile (6 mL), 4 2 mixture was heated at 180C under a positive pressure of argon until the disappearance of the Q band of 4 2 (approx. 3 hours). The solvent was removed by vacuum dis tillation and the crude was purified by passing through a short plug of neutral silica under an argon atmosphere with DCM. The solvent was removed under reduced pressure to give 25 mg of the title compound (38%). 1H NMR ( pyridined5, 500 MHz ): 8.71 (s, 8H), 8.53 (s, 4H), 8.53 (overlap s, 8H), 8.30 (s, 8H), 8.11 (d, 8H), 7.52 (t, 8H), 1.58 (s, 72H) ; 13C NMR ( pyridine d5, 125 MHz 154.5, 136.6, 132.8, 130.4, 129.1, 128.7, 128.2, 126.3, 125.2, 123.4, 118.5, 35.8, 32.1; MALDI TOF MS [M]+ 18 56.8951, calcd 1856.8872. Platinum 5,15 Diphenyltetrabenzoporphyrin ( Pt 4 5 a). The title compound was prepared from 4 5 a and platinum acetate in benzonitrile (25 mL) using the procedure for Pt 39a The material was loaded on silica, eluting with DCM removing the green band ( 4 5 a ). The solvent was changed to an increasing gradient with a THF:DCM mixture (30:70). The dark blue band was collected yielding 16 mg of the title compound (25%). Analogously to the reported palladium complex NMR analysis was not possible due to low solubility of Pt 4 5 a in common NMR

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93 solvents.61 The material was characterized by UV VIS and mass spectrometry. UV Vis, max: 409 nm, 547 nm, 595 nm, 604 nm; MALDI TOF MS [M]+ 852.4518, 854.1971, 855.2001, 856.2019, 857.2050, 858.2057, 859.2082, 860.2094, 861.4855, calcd 852.1919, 854.1935, 855.1960, 856.1974, 857.1999, 858.2004, 859.2026, 860.2054. Plati num 5,15 D i(3,5 di tertbutylphenyl)tetrabenzoporphyrin ( Pt 4 5 b). The title compound was prepared from 4 5 b and platinum acetate (100 in benzonitrile (30 mL) using the procedure for Pt 39 a The s olvent was removed and the crude material loaded on silica eluting with 15% DCM in Hexane collecting the blue band. The material was further purified from multiple precipitations from boiling CHCl3 and MeOH. The precipitate was collected and repeatedly was hed with MeOH yielding 25 mg of the title compound (32%). 1H NMR ( pyridined5, 500 11.55 (s, 2H), 9.80 (d, 4H), 8.35 (s, 4H), 8.31 (s, 4H), 8.08 ( t, 4 H), 7.78 (t, 4 H), 7.54 (d, 4H) ; 13C NMR ( pyridined5, 125 153.1, 141.5, 139.0, 138.2, 136.6, 136.2, 128.1, 127.7, 126.4, 122.8, 121.5, 121.0, 97.5, 35.9, 32.0 ; ESI TOF [ M]+ 1080.4543, calcd 1080.4481. Platinum 5,15 Di( ( 3,5 di tertbut ylphenyl) p henyl)tetrabenzoporphyrin (Pt 4 5 c ). The title compound was prepared from 4 5 c ( 110 mg, 92.3 and platinum acetate ( 127 mg, 92.3 in benzonitrile (25 mL) using the procedure for Pt 39 a Separation with column chromatography failed due to solubility and small differences in Rf values. The title compound was purified by multiple precipitations from DCM and MeOH to give 70 mg (55 %). 1H NMR ( pyridined5, 5 11.60 ( s, 2H), 9.86 (d, 4H), 8.93 (s, 2H), 8.84 (s, 4H), 8.12 (d, 8H), 8.08 (t, 4H), 7.99 (d, 4H), 7.81 (t, 4H),

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94 7.63 (d, 8H), 1.34 (s, 36H) ; 13C NMR ( pyridined5, 125 151.8, 143.5, 139.1, 138.3, 138.2, 136.8, 130.5, 128.2, 128.0, 127.8, 126.9, 126.9, 126.3, 121.8, 120.0, 35.0, 31.7 ; DART MS [M+H]+ 1383.5772, calcd 1383.5770. Platinum 5,15 Di(3,5 di tertbut ylphenyl)octa propyltetrabenzoporphyrin (Pt 4 5 d). The title compound was prepared from 4 5 c ( 33 mg, 23.2 and platinum acetate ( 32 mg, 23.2 in benzonitrile (20 mL) using the procedure for Pt 39 a After vacuum distillation to remove benzonitrile the crude material was loaded on silica and eluted with a hexane:DCM mixture (85:15) collecting the f irst blue band. The fractions w ere concentrated and the material precipitated by the addition of excess MeOH. The precipitate was collected to give 22 mg of the title compound (58%). 1H NMR ( pyridined5, 5 11.86 (s, 2H), 9.83 (s, 4H), 8.36 (s, 2H), 8.33 (s, 4H), 7.42 (s, 4H), 3.11 (t, 8H), 2.95 (t, 8H), 1.90 (sex, 8H), 1.82 (sex, 8H), 1.63 (s, 36H), 1.18 (t, 12H), 1.12 (t, 12H) ; 13C NMR ( pyridined5, 125 153.0, 140.7, 140.4, 137.6, 136. 8, 127.7, 126.8, 123.5, 121.7, 120.3, 97.0, 36.4, 35.9, 32.2, 25.6, 15.0 ; ESI TOF m/z 1416.8265, calcd 1416.8301.

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95 CHAPTER 3 PHOTOPHYSICS AND DEVICE RESULTS Introduction Photoluminescence is the proces s of photons being emitted by either a fluorophore to give fluorescence or alternatively a phosphor to give phosphorescence described earlier in C hapter 1. E lectroluminescence is the process of generating an excited state by the application of an electric field and the emission of photons upon relaxation o f the excited species The first report of electroluminescence was by Destriau using microcrystals of ZnS suspended in an insulating medium sandwiched between two electrodes.105, 106 This sparked the development and commerci alization of numerous inorganic materials with a wide variety of emission wavelengths. Cathode / Aluminum Emissive layer / Alq3 Anode / ITO Substrate A Cathode / Aluminum Emissive layer / PPV Anode / ITO Substrate B Figure 31. Single layer device structure for the first reported OLED and PLED. A) Vapor deposited small molecule OLED with Alq3 as the emissive material. B) Solu tion processed polymer based PLED with PPV as the emissive material. Electroluminescence from organic materials was first described in 1963.107, 108 The use of anthracene crystals as the emitting species resulted in low efficiency and requi red highfield strengths and resulted in an overall lack of interest in the use of organic based materials for electroluminescence. A breakthrough occurred almost twenty five years later when Tan g and Van Slyke reported green emission upon application of an electric field to single layer devices fabricated by thermal vapor

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96 deposition of aluminum tris ( 8 hydroxyquinolinate) (AlQ3) onto indium tin oxide (ITO) followed by the thermal vapor depositi on of an aluminum electrode shown in Figure 31A .55 Another important milest one was reached in 1990 when the Friend et al prepared the first polymer light emitting diode (PLED).109 The device was fabricated from a sandwiched thin film of poly(pphenylenevinylene) (P PV) between two electrodes Al and ITO outlined in Figure 31B The application of a voltage to the device produced yellow green light Thus this work along with the work from Tang and Van Slyke can be regarded as the seminal wor ks for the development of the organic LED field. The present day research area of OLEDs and PLEDs has grown significantly with devices in both areas at the point of commercialization.110 113 Electroluminescence Mechanisms The simplest description of electroluminescence would be the conversion of electrons and holes into photons. The actual process can be broken down into four steps: (1) charge injection into the device, (2) charge transport to the emissive layer, ( 3) chargerecombination resulting in the formation of an excited state on the radiative material and (4) radiative relaxation of the generated excited state. One mechanism for generating electroluminescence known as intrinsic electroluminescence has been d emonstrated by Bernanose using cel lophane films or in perylene and anthracene crystals.114116 This requires the acceleration of electrons known as hot carriers to impact the radiative material generating the excited state. However because high ac voltages ar e often required which leads to electrical breakdown, it is difficult to generate intrinsic electroluminescence in organic materials.

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97 A more successful method of introducing charge carriers into organic materials involves sandwiching the electroactive mat erials between electrodes. Application of an electric field at the electrodes effectively injects electrons and holes into the material. The use of a low work function metal at the cathode allows for electrons to be easily injected into the lowest unoccupi ed molecular orbital (LUMO) and in chemical terms reduces the electroactive material. This is analogous to injecting electrons into the conduction band (Ec) of inorganic semiconductors The cathode is typically made from calcium, magnesium, or aluminum. O nce the electrons are injected into the device near the cathode, simultaneously the anode injects holes into the highest occupied molecular orbital (HOMO) of the active material in an analogous fashion to the valence band (Ev) inorganic semiconductors. The formation of holes or more simply the remov al of electrons is the oxidation of the electroactive material The anode is most often indium tin oxide primarily for its high work function and good transmission properties (transparency) in the visible region. Now that both holes and electrons have been injected into the active material they begin to drift towards the oppositely charged electrode. This eventually leads to recombination of both holes and electrons on the emissive material generating an excited s tate that may radiatively or nonradiatively decay. The choice of whether to use fluores cent or phosphorescent emitters becomes clear upon examination of the recombination process of electrons with holes. This can lead to an electron configuration on the emissive material to be either a singlet state (S= ) or a triplet state (S=1). Recombination of electrons and holes affords a statistical distribution of singlet excitons (25%) and triplet excitons (75%). This means that use of

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98 fluorescent emitters (i.e. emission from the S1) are limited to a maximum efficiency of 25%. However the use of phosphorescent materials allows for use of both singlet and triplet states. W here the singlet states can intersystem cross to the triplet state and then radiativel y decay (phosphorescence) device efficiency can reach the theoretical limit of 100% internal quantum efficiency. Materials with very high phosphorescence quantum yields are desirable and can potentially be used to fabricate highly efficient PLEDs and OLEDs. Cathode Electron Transport Layer (ETL) Emitting Layer Hole Transport Layer (HTL) Anode Substrate Cathode ETL Emitting Layer HTL Anode Conduction Band (LUMO) Valence Band (HOMO )Hole Injection Electron Injection Figure 32. Device structure of a multilayer light emitting diode with a diagram of electroluminescence mechanism. Organic Light Emitting Diodes The term OLED refers to devices fabricated from the thermal vapor deposition (sublimation) of s mall mole cules the substrate. The term PLED refers to devices fabricated from spin coating solution processable polymer s on to the substrate. The electron configuration of the excited material after the recombination of electrons with holes is not the only contributi ng factor to device efficiency The rates at which the holes and electrons migrate through the materials to eventually recombine on the desired emitting species are important. Typically in most organic materials the hole

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99 mobility is far higher than the electron mobility. This problem is circumvented by more complicated device structures with layers of materials that either increase or decrease the carrier mobilities. An example of this device structure is shown in Figure 32. Figure 33. Examples of small molecule hole transport materials. TPA is triphenylamine, TPD is (N,Ndiphenyl N,Nbis(3 methylphenyl) 1,1biphenyl 4,4 amine and NPB is N,Nbis(naphthalene-1yl) N,Nbis(phenyl)benzidine. Electron transport layers (ETL) and hole transport layers (HTL) serve dual purposes in that they can alter the overall electron and hole mobilities respectively, w hile at the same time restricting the transport or injection of the opposite carrier. This allows the holes and electrons to be trapped in the emissive layer (EML) of the device. T he hole transport layer s are generally materials with large energy gaps ( EHOMO LUMO) usually consisting of amines with low ionization potentials. These properties allow for the holes to be more easily injected while also providing a large barrier to electron injection from the EML. Examples of small molecules that can be vapor deposited for HTLs are shown in Figure 3-3 Figure 34. Examples of small molecule host materials. CBP is 4,4 bis(N carbazolyl) 1,1 biphenyl, Alq3 is tris (8 hydroxyquinoline)aluminum and MCP is 1,3bis(carbazol -9yl)benzene.

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100 The emissive layer of the device can either be a single material (neat) or an emissive material doped into a polymer or small molecule host at some concentrati on. The first OLEDs and PLEDs were fabricated as single layer devices (Figure 31). However it has been shown to be a d vantage ous to use a host material to prevent various quenching mechanisms induced by having a neat layer of the emitting species. Common host materials used in the fabrication of OLEDs are outlined in Figure 3-4 The host materials are paired with the emitting species based on spectral overlap of the host emission spectrum (usually fluorescence) with the absorption of the emitter. This allows for efficient F r ster energy transfer efficiently quenching the host emission. The materials may also be prepared such that the HOMO and LUMO of the emitting species lie within the HOMO and LUMO levels of the host, thus leading to charge trapping on the emitting species. Figure 35. Examples of small molecule electron transport materials. Bphen is 4,7diphenyl 1,10-p henanthroline, 3TPYMB is tris(2,4,6trimethyl -3(pyridine-3yl)phenyl)borane, and TAZ is 3(4 biphenylyl) -4phenyl -5tert butylphenyl 1,2,4triazole. In between the cathode and the EML a layer of electron transport materials are deposited to facil itate ba lanced charge transport within the device with more efficient electron injection. In general these materials exhibit high electron mobilities and are chosen to have deep HOMO energy levels to block hole transport to the cathode.

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101 Common materials used for OLED electron transport layers (ETL) are shown in Figure 3-5 The ability to block holes from reaching the cathode helps in trapping the carriers in the EML for hole and electron recombination on the emissive species. Polymer Light Emitting Diodes The de vices composed of polymers for either the EML or as a host material are known as polymer light emitting diodes (PLEDs). Figure 36 outlines common polymers used for these devices. Most of the advantages in using polymeric materials for LEDs stem from the ability to solution process the materials over the thermal vapor deposition method used for OLEDs However in most cases device efficiencies for PLEDs are lower than a small molecule based OLED using the same emitter. The main reasons for the differences i n device efficiencies are the difficulty in confining the holes and ele ctrons to the EML Since t he use of common solvents in processing prevents deposition of multiple layers multilayer device architectures in which the holes and electrons are confined t o the active layer are generally not used. Without the addition of HTL and ETL layers, the carriers in PLEDs can mi grate across the device and reach the opposite ele ctrode without recombination, thus resulting in lower efficiency Figure 3-6 Examples of polymer host materials for polymer light emitting diodes. MEH PPV is poly[2 methoxy -5(2 ethylhexyl oxy) 1,4phenylenevinylene], PFO is poly(9,9di -noctylfluorenyl 2,7 diyl and PVK:PBD is poly(9vinylcarbazole) blended with 2(4 biphenylyl) -5phenyl 1, 3,4 oxadiazole.

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102 Results and Discussion Presented herein are th e photophysical properties for three series of extended platinum porphyrins previously o utlined in Chapter 2 (Figure 22 ). Also reported are the performance of these materials in PLEDs and OLEDs using each series of extended platinum porphyrins as the near IR phosphor s Specifically this work advances the field of near IR LEDs by the realization of electroluminescence in new wavelength regions of the near IR using these novel phosphors. For the first time the solution photophysics of extended platinum porphyrins are reported setting PL efficiency records in their respective wavelengths regions Record device efficiencies are obtained from use of these phosphors for near IR LED applications. Series 1 Photophysic al Properties The structures of the free base and platinum complexes for extended porphyrins for S eries 1are shown i n Figure 37 The goal of these target compounds is to red shift the emission wavelengths further into the near IR through increasing the conjugation to the porphyrin macrocycle. Platinum complexes for TNP and TAP systems have not been reported and this work represents the first known report of the photophysical properties for these targets. Gouterman showed early on that the major effect of extending conjugation to the porphyrin macrocycle (via fused benzorings) was a large red shift in the Q band with the transition becoming significant ly mor e allowed ( intense), however only a small red shift is observed for the S oret band.1820 The absorption and photoluminescence in air saturated toluene for series 1 freebase porphyrins is shown in Figure 38, w hile the absorption and emission wavelength maxima, molar absorption coefficients emission quantum yields and S1 lifetime s are listed in Table 31

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103 Figure 37. Structures for series 1 extended freebase and platinum porphyrins The addition of fusedbenzo rings to the porphyrin macrocycle from H2TPTBP to H2Ar4TAP results in approximately a 200 nm red shift of the Qband. This results in the transition being shifted from the red region of the visible (H2TPTBP) to being completely in the near IR region (H2Ar4TAP). The Q band becomes more allowed across the series and is noted by the increase in molar absorptivity constant ( = 3.32 x 104 1.95 x 105 M-1 cm-1) by an order of magnitude f rom H2TPTBP to H2Ar4TAP. However the S oret band across the series is only red shifted 50 nm from H2TPTBP to H2Ar4TAP. The transition is strongly allowed and remains in the visible region of the spectrum ( ~2 3 x 105 M-1 cm-1). The photoluminescence for s eries 1 freebase porphyrins were obtained by excitation of the Soret band (Figure 38). The quantum yields (QY) were referenced to ZnTPP in toluene (QY 0.04)117 while the S1 decays were obtained by single photon counting and were all monoexponential in nature shown in Figure A 1. A small Stokes shift is observed with the S1 emission maxima relative to the lowest energy absorption. The emission maxima are red shifted approximately 140 nm (H2TPTBP to H2Ar4TAP) across the series. The quantum yield for H2TPTBP in toluene is in agreement with the

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104 reported literature value.61 T he increase in the QY s for H2TPTNP and H2Ar4TNP(OMe)8 reflect the increase in kr values consistent with an increase in the allowedness of the S1So transition, and in line with other values reported for H2Ar4TNP systems.58 Ono et al have reported the PL spectra for two fluorescent ZnTAPs, however photophysical characteriz ation of a freebase TAP has not been reported.66 The PL for H2Ar4TAP is dominated by emission at 841 nm with a vibronic should at 932 nm. The low intensity broad emission in the visible region is likely from the anthracene fragments in the TAP macrocycle. The QY for H2Ar4TAP (6.8%) is higher than the reported QYs for ZnTAPs (3.7 4.3%) which are expected to be lower due to the increase rate in ISC. Table 3 1 Photophysical properties of Series 1 freebase extended porphyrins in air saturated toluene. Fluorescence quantum yields were meas ured relative to ZnTPP (0.04) with excitation at 420 nm in toluene. The S1 decays were obtained by single photon counting method. Freebase Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 cm 1 ) Fluorescence max nm fl fl (ns) H2TPTBP 465, 633 465 = 3.03 x 105 633 = 3.32 x 10 4 704, 785 4.1% 0.1 3.1 H2TPTNP 500, 728 500 = 2.25 x 105 728 = 1.06 x 10 5 756, 840 19% 0.2 3.9 H2Ar4TNP(OMe)8 502, 730 502 = 2.64 x 105 730 = 1.18 x 10 5 755, 837 23% 0.1 4.6 H2Ar4TAP 510, 824 510 = 2.11 x 105 824 = 1.95 x 10 5 841, 932 6.8% 0.5 1.0 The decrease in the S1 lifetime and quantum yield for H2Ar4TAP compared to H2TPTBP follows the energy gap law.118, 119 This states that as the difference in energy between the ground state and excited state gets smaller the rate of nonradiative decay

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105 will increase, thus decreasing the radiative rate and QY The deactivation rate constants for the S1 state for series 1 freebase extend porphyr ins were calculated and summarized in Table 3 2 The radiative rate constant ( kr) across the series increases from H2TPTBP to H2Ar4TAP about 5.2 times. The nonradiative rate constant ( knr) also increases across the series about 3 times. This results in th e observed decrease in S1 lifetimes across the series. Table 3 2 D eactivation rate c onstants for S1 state of series 1 freebase extended porphyrins in air saturated toluene. Radiative decay rate constant ( kr), calculated as kr = flk, and the nonradiative decay rate constant ( knr = kic + kisc), calculated as kr = k knr. Freebase Porphyrins k = 1/ fl (s1) kr (s1) knr (s1) fl (ns) H 2 TPTBP 3.2 x 10 8 1.3 x 10 7 3.1 x 10 8 3.1 H 2 TPTNP 2.6 x 10 8 4.9 x 10 7 2.1 x 10 8 3.9 H 2 Ar 4 TNP(OMe) 8 2.2 x 10 8 5.1 x 10 7 1.7 x 10 8 4.6 H 2 Ar 4 TAP 1.0 x 10 9 6.8 x 10 7 9.3 x 10 8 1.0 The absorption and photoluminescence in deoxygenated toluene for series 1 extended platinum porphyrins is shown in Figure 39. The absorption and emission wavelength maxima for the series are summarized in Table 33 along with the molar absorption coefficients, phosphorescence QYs and T1 lifet imes. The insertion of platinum changes the porphyrin symmetry to D4h. The absorption spectra are blue shifted relative to the respective freebase absorptions. This is due to the donated dorbitals of the porphyrin res ulting in metal to ring charge transfer giving irregular hypsotype spectra. The relative intensities between the Soret and Q bands have also changed. The insertion of the metal makes the Q band transition more allowed ( ~4 5 x 104 1 2 x 105 M1 cm1). In the case of

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106 platinum TNP and TAP systems the Q band surpasses the Soret in intensity giving very strong absorptions in the deepred to near IR region of the spectrum. 0.0 0.2 0.4 0.6 0.8 1.0 Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 400 600 800 1000 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength (nm)A B C D F igure 38 Normalized absorption (black) and photoluminescence (red) of Series 1 f ree base exte nded porphyrins in toluene: A) H2TPTBP, B) H2TPTNP, C) H2Ar4TNP(OMe)8, D) H2Ar4TAP.

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107 Table 3 3 Photophysical data for series 1 extended platinum porphyrins in deoxygenated toluene. Quantum yields were measured relative to ZnTP P (0.04) by excitation at 420 with the exception of Pt Ar4TAP which was measured relative to H2TPTBP (0.041) with excitation at 420 nm. The T1 lifetimes were obtained by transient absorption spectroscopy. Platinum Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 c m 1 ) Phosphorescence max nm phos T T EST (eV) Pt TPTBP 430, 612 430 = 1.91 x 105 612 = 1.35 x 10 5 773 46% 5 29.9 0.33 Pt TPTNP 436, 689 436 = 9.17 x 104 689 = 1.50 x 10 5 891 20% 0.1 12.7 0.34 Pt Ar4TNP(OMe)8 455, 690 455 = 8.30 x 104 690 = 1.32 x 10 5 883 16% 0.5 15.3 0.32 Pt Ar4TAP 455, 762 455 = 2.99 x 104 762 = 4.64x 10 4 1022 11% 2 3.2 0.35 Table 3 4 Deactivation rate constants for T1 st ate of series 1 extended platinum porphyrins in deox ygenated toluene. Radiative decay rate constant ( kr), calculated as kr = phosk, and the nonradiative decay rate constant ( knr = kic + kisc), calculated as kr = k knr. Platinum Porphyrins k = 1/ T T (s1) kr (s1) knr (s1) T T Pt TPTBP 3.3 x 10 4 1.5 x 10 4 1.8 x 10 4 29.9 Pt TPTNP 7.9 x 10 4 1.6 x 10 4 6.3 x 10 4 12.7 Pt Ar 4 TNP(OMe) 8 6.5 x 104 1.0 x 104 5.5 x 104 15.3 Pt Ar 4 TAP 3.1 x 10 5 3.5 x 10 4 2.8 x 10 5 3.2 The photoluminescence spectra from series 1 extended platinum por phyrins are dominated by a single phosphorescence band with a weak vibronic shoulder. The platinum center dramatically increases the rate of ISC from S1 to the T1 state via the

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108 heavy atom effect. The porphyrins are now strongly phosphorescent and no longer fluorescent. Moving across the series from Pt TPTBP to Pt Ar4TAP the expected trend based on the energy gap law of a decrease in both the lifetime and quantum yield are observed. The Singlet Triplet energy splitting (EST) was calculated from approximating the singlet energy level at the onset of the lowest energy Q band and the emission maximum and remains relatively constant across the series. The nonradiative rate constant (Table 34) increases about 3 times from Pt TPTBP to the Pt TNPs and for Pt Ar4TA P is an order of magnitude higher compared to Pt TPTBP. T he QYs were measured in deoxygenated toluene using ZnTPP as an actinometer except for Pt Ar4TAP which was measured relative to H2TPTBP The T1 lifetimes were determined from transient absorption spectroscopy. The photoluminescence spectrum for Pt TPTBP is identical to that reported in the literature. The reported quantum yield and lifetime (53 s, 0.70) for Pt TPTBP by Thompson et al are different from our measurements (29.9 s, 0.43) but in line wi th those from Kilmant et al .53, 57 However, absent from the literature was a report for a platinum TNP and its photophysical properties. The PL spectra for Pt TPTNP is red shifted (~100 nm) relative to Pt TPTBP. The quantum yield (0.20) and lifetime (12.7 s) are lower compared to that of Pt TPTBP. Based on a literature report for a palladium octamethoxy substituted TNP it was expected that the PL for Pt Ar4TNP(OMe)8 would be red shifted relative to Pt TPTNP; however this is not observed. The red shift reported in the literature is believed to originate from a pushpull effect created by ester substituents (electron withdrawling) in the 3,5 positions in the meso aryl substituents.120

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109 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength (nm) 400 600 800 1000 1200 Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 A B C D Figure 39 Normalized absorption (black) and photoluminescence (red) for s eries 1 extended platinum porphyrins in toluene: A) Pt TPTBP, B) Pt TPTNP, C) Pt Ar4TNP(OMe)8, D) Pt Ar4TAP A Pd TAP derivative has been reported without PL spectra (phosphorescence) in the literature with a QY of less than 0.5% with emission reported at 1.12 eV (1107 nm).

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110 To our knowledge this represents the first full report and photophysical characterization of a phosphorescent TAP and more specifically a platinum TAP. The PL spectrum for Pt Ar4TAP is centered at 1022 nm with a life time of 3.2 s measured by transient absorption spectroscopy. The phosphorescence QY was measured relative to H2TPTBP as the Soret bands are separated by ~20 nm and S1 emission (704,788 nm) is in a region of good sensitivity for the near IR detector. The QY measured for Pt Ar4TAP w as 11%. Multiple measurements could not be made from the same solution as severe bleaching occurred and so error bars of ~20% are assumed. Nonetheless the room temperature phosphorescence yields of series 1 extended platinum porphyrins represent the highest that have ever been reported for materials that emit at approximately ~800, 900, and 1000 nm regions of the near IR. Series 1PLED Device Results PLEDs were fabricated by the Reynolds group (Ken Graha m) at the University of Florida. S pin coating the active layer on top of a PEDOT:PSS layer, followed by evaporation of the metal electrode materials to give the following device structure: glass/ITO/PEDOT:PSS (40 nm) / 2% Pt porphyrin:PVK:PBD (7:3) (110 nm) /Li F (1 nm) /Ca (10 nm) /Al. However, PLEDs fabricated with this device structure displayed very poor performance for Pt Ar4TAP. A hybrid device structure ad opted by thermal vapor deposition of an ETL (Bphen) to give a new device structure of glass/ ITO/PEDOT:PSS ( 40 nm) /PVK:PBD(7:3):2% Pt Ar4TAP (110 nm) /Bphen(40 nm)/LiF(1 nm)/Al was used in efforts to increase device efficiency. Electroluminescence (EL) across the series for series 1 PLEDs is centered at 771, 898, 892, and 1005 nm for Pt TPTBP, Pt TPTNP, Pt Ar4TNP (OMe)8, and Pt Ar4TAP respectively with no host emission observed (Figure 310A). Light emission from the

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111 PLEDS turns on at an applied voltage of ~817 V observed in the R V plot (Figure 310C). Similar current densities are observed in the JV plot (Figur e 3 10B) but expected as only the near IR phosphor is changing in the device structures. Overall the PLEDs operate at relatively high voltages due to the thickness of the emissive layer and the high electron and hole injection barriers. J (mA/cm 2 ) 1e-1 1e+0 1e+1 1e+2 EQE (%) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Wavelength (nm) 600 800 1000 1200 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Voltage (V) 0 5 10 15 20 25 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 Voltage (V) 5 10 15 20 25 R ( W/cm 2 ) 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 A B C D Figure 310. PLED device results for series 1 extended platinum porphyrins. Pt TPTBP (black), Pt TPTNP (red), Pt Ar4TNP(OMe)8 (green), and Pt Ar4TAP (blue) with the following device structure: glass/ITO/PEDOT:PSS(40 nm)/ 2% Pt porphyrin:PVK:PBD (7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al A) EL spectra for PLEDs, B) JV plot, C) R V plot, D) External quantum efficiency. Although the hybrid PLED device structure for Pt Ar4TAP has a significantly lower turn on voltage due to the ETL (Figure 311B). The PLEDs across the series exhibit

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112 maximum radiant e mittance of approximately 1001000 W/cm2. The maximum external quantum e fficiencies (EQE) for the series range from 0.041.5%. The PLED fabricated from Pt TPTBP gave the highest EQE while Pt Ar4TAP gave the lowest EQE of 0.04% shown in Figure 310D. The Pt TPTNP and Pt Ar4TNP(OMe)8 based P LEDs gave maximum EQE values of 0.74 and 0.36%. Wavelength (nm) 700 800 900 1000 1100 1200 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Voltage (V) 0 2 4 6 8 10 12 14 16 J (mA/cm 2 ) 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 R (mW/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 J (mA/cm 2 ) 1e-1 1e+0 1e+1 1e+2 1e+3 P (mW/W) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 J (mA/cm 2 ) 1e-1 1e+0 1e+1 1e+2 1e+3 EQE (%) 0.0 0.1 0.2 0.3 0.4 A B C D Figure 311. Hybrid PLED device for Pt Ar4TAP with device structure: glass/ITO/PEDOT:PSS(40 nm)/PVK:PBD(7:3):2% PtAr4TAP(110 nm)/Bphen(40 nm)/LiF(1 nm)/Al A) EL spectrum, B) JV plot (closed circles) and R V (open circles), C) Power efficiency, D) External quantum efficiency. The device performance of Pt Ar4TAP in the hybrid PLED device structure is shown in Figure 311. EL from the device is identical to that from the Pt Ar4TAP based PLED (Figure 3 11A). The device featured maximum radiant emittance of ~1 mW/cm2 at approximately 12 volts shown in Figure 311B. The maximum EQE value (Figure 311D)

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113 for the hybrid device was ~0.25 which is around 5 times higher than the Pt Ar4TAP based PLED. Series 1 OLED Device Results Due to the high molecular weight of Pt Ar4TNP(OMe)8 and Pt Ar4TAP thermal vapor deposition for OLEDs was not possible. Thus, OLEDs were only constructured using Pt TPTBP and Pt TPTNP. Thompson et al have previously reported an OLED using Pt TPTBP as the near IR phosphor with an overall EQE of 8.5%.53, 67 M ultilayer OLED s were fabricated by the Xue group at the University of Florida (Yixing Yang) with Pt TPTBP having the following device s tructure : ITO/NPB(40 nm)/Alq3:4% Pt TPTBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/Al Another multilayer device was fabricated with Pt TPTNP representing the first report ed use of this material in an OLED with the following device structure: ITO/NPB(40 nm)/CBP:8% P t TPTNP(20 nm)/Bphen(100 nm)/LiF(1 nm)/Al Electroluminescence from the Pt TPTBP and Pt TPTNP OLEDs is centered at 773 nm and 890 nm, respectively, similar to the EL for the respective PLEDs (Figure 312A). The R V plot (Figure 312B) shows that light emission for both devices is observed at a rather low turn on voltage of ~2 V. The maximum radiant emittance for the Pt TPTBP based OLED is 1 mW/cm2 obtained at ~12V (Figure 311B). Similarly the maximum radiant emittance of the Pt TPTNP based OLED is 1 m W/cm2 obtained at ~10 V (Figure 3 11B). The EQE data shown in Figure 312D for the OLED fabricated with Pt TPTBP gave a maximum EQE of 8.0%, in good agreement with the literature value of 8.5%. The Pt TPTNP based OLED displays a maximum EQE of 3.8%. The lower EQE of a Pt TPTNP based OLED relative to a Pt TPTBP based OLED follows the trend for the phosphorescence QYs and lifetimes of the materials (3.8%, 0.201, and 12.7 s) and

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114 (8.0%, 0.459, and 29.9 s) respectively. Although the EQE value for Pt TPTNP bas ed OLEDs is lower it represents a new record for devices emitting beyond 800 nm. Voltage (V) 0 2 4 6 8 10 12 14 16 18 J (mA/cm 2 ) 1e-8 1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 R (mW/cm 2 ) 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 Wavelength (nm) 600 700 800 900 1000 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 P (mW/W) 0 10 20 30 40 50 60 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 EQE (%) 0 2 4 6 8 10 A B C D Figure 312. OLED device results for series 1 extended platinum porphyrins. Pt TPTBP (black), Pt TPNP (red), with device structures : glass/ ITO/NPB(40 nm)/Alq3:4% Pt TPTBP (25 nm)/Bphen(80 nm)/LiF(1 nm)/Al and glass/ ITO/NPB(40 nm)/CBP:8% PtTPTNP(20 nm)/Bphen(100 nm)/LiF(1 nm)/Al A) EL spectra for OLEDs, B) JV plot (closed circles) and R V (open circles), C) Power efficiency, D) External quantum efficiency. Series 2Photophysical Properties The recent report of Pd5,15diaryl TBPs by Vinogradov et al is the primary basis for developing the free base and Pt TBPs for ser ies 2 outlined in Figure 313 .61 They report the solution phosphorescence QY for Pd DPTBP to be twice that of PdTPTBP and half that of a soluble meso unsubstituted Pd TBP. This trend is observed due to an increase in macrocycle planarity which decreases the non radiative decay rate thus

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115 increasing the lifetime and QY. Ikai et al have also reported that 3,5di tert butylphenyl meso aryl substituents provide facial sterics leading to enhanced device efficiency in platinum porphyrin based LEDs.78 The following series was developed to expand the known literature work on Pt TBPs. It is expect ed, that the Pt5,15 diaryl TBPs will exhibit a QY twice that o f Pt TPTBP and Pt Ar4TBP based on an increase in the planarity of the macrocycle. Also examined are the effect of bulky meso aryl substituents (3,5-tBuPh) on device efficiency across the series. This represents the first known report for the synthesis and photophysical characterization of platinum 5,15 diaryl TBPs. Figure 313. Structures of free base and platinum complexes for series 2 TBPs. The absorption and photoluminescence in air saturated toluene for series 2 freebase TBPs is shown in Figure 314. The absorption spectra for H2TPTBP and H2DPTBP are identical to those previously reported in the literature. The absorption spectra for H2Ar4TBP and H2Ar2TBP are identical to the respective phenyl derivatives with only a small red shift observed (1 2 n m) in each case. In both diaryl and tetraryl TBPs the S oret band is strongly allowed in the visible region with high molar absorptivity values (2 3 x 105 M-1 cm-1). The absorption spectra for H2DPTBP and H2Ar2TBP show well

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116 resolved vibronic structure in b oth the Soret and Q band. The large splitting (841 cm1) in the Soret band of 5,15diaryl TBPs is attributed to the strong mixing of the Soret and Q band states.19, 121, 122 These spectra resemble red shifted meso u nsubstituted TBPs and strongly suggest there is little difference in macrocycle planarity between 5,15diaryl TBPs and meso unsubstituted TBPs This increase in planarity results in both the absorption and PL being sharper and blue shifted relative to the tetraaryl derivatives. T he photophysical data for series 2 free base TBPs is summarized below in Table 35 Table 3 5 Photophysical properties of Series 2 freebase TBPs in air saturated toluene. Fluorescence quantum yields were measured relative to ZnTP P (0.04) with excitation at 420 nm in toluene. The S1 decays were obtained by single photon counting method. Freebase Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 cm 1 ) Fluorescence max nm fl fl (ns) H2TPTBP 465, 633 465 = 3.03 x 105 633 = 3.32 x 10 4 704, 785 4.1% 0.1 3.1 H2Ar4TBP 462, 630 462 = 3.21 x 105 630 = 4.14 x 10 4 701, 779 4.3% 0.1 3.5 H2DPTBP 440, 612 440 = 3.62 x 105 612 = 6.81 x 10 4 671, 738 37% 4.0 10.6 H2Ar2TBP 440, 612 440 = 3.83 x 105 612 = 6.70 x 10 4 671, 738 38% 4.0 10.3 The absorption and photoluminescence in deoxygenated toluene for series 2 platinum TBPs is shown in Figure 315. The photophysical data for series 2 platinum TBPs is summarized and reported in Table 37. The absorption spectra for series 2 platinum TBPs are blue shifted relative to the freebase TBPs and indicative of porphyrins with local D4h symmetry ( metal center).

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117 Table 3 6 Deactivation rate constants for S1 state of series 2 freebase TBPs in air saturated toluene. Radiative decay rate constant ( kr), calculated as kr = flk, and the nonradiative decay rate constant ( knr = kic + kisc), calculated as kr = k knr. Freebase Porphyrins k = 1/ fl (s1) kr (s1) knr (s1) fl (ns) H 2 TPTBP 3.2 x 10 8 1.3 x 10 7 3.1 x 10 8 3.1 H 2 Ar 4 TBP 2.9 x 10 8 1.2 x 10 7 2.7 x 1 0 8 3.5 H 2 DPTBP 9.4 x 10 7 3.5 x 10 7 5.9 x 10 7 10.6 H 2 Ar 2 TBP 9.7 x 10 7 3.7 x 10 7 6.0 x 10 7 10.3 Table 3 7 Photophysical data for series 2 platinum TBPs in deoxygenated toluene. Quantum yields were measured relative to ZnTPP (0.04) by excitati on at 420 nm in toluene. The T1 lifetimes were obtained by transient absorption spectroscopy. Platinum Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 cm 1 ) Phosphorescence max nm phos T T Pt TPTBP 430, 612 430 = 1.91 x 105 612 = 1.35 x 10 5 773 46% 5 29.9 Pt Ar4TBP 432, 610 432 = 1.81 x 105 610 = 1.05 x 10 5 772 44% 0.3 32.0 Pt DPTBP 409, 604 409 = 2.68 x 104 604 = 2.13 x 10 4 770 40% 2 28.0 Pt Ar2TBP 410, 604 410 = 1.73 x 105 604 = 1.32 x 10 5 770 65% 8 53.0 As expected the absorption spectra for Pt TPTBP and Pt Ar4TBP are virtually identical. The vibronic structure observed in the Q bands for platinum 5,15diaryl TBPs most likely results from the unsymmetrical nature of the macrocycle. As stated earlier the insertion of the metal makes the Q band transition more allowed with the molar absorptivity

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118 constants in the platinum 5,15 diaryl TBPs being ~20% higher than Pt TPTBP or Pt Ar4TBP. The Soret band is the most intense transition (12 x 105 M1 cm1) across the series in the absorption spectra located in the visible region. The very low solubility of Pt DPTBP is likely the reason for the low value. Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength (nm) 300 400 500 600 700 800 900 0.0 0.2 0.4 0.6 0.8 1.0 A B C D Figure 314. Normalized absorption (black) and photoluminescence (red) of series 2 free base TBPs in toluene: A) H2TPTBP, B) H2Ar4TBP, C) H2DP TBP D) H2Ar2TBP.

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119 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 400 600 800 1000 0.0 0.2 0.4 0.6 0.8 1.0 A B C DWavelength (nm)Normalized Intensity Figure 315. Normalized absorption (black) and photoluminescence (red) for series 2 platinum TBPs in toluene: A) Pt TPTBP, B) Pt Ar4TBP, C) Pt DPTBP, D) Pt Ar2TBP.

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120 The photoluminescence spectra for series 2 platinum TBPs are shown in Figure 315. The PL spectra are dominated by a single phosphorescence band with a w eak vibronic shoulder. The maximum emission wavelengths for Pt TPTBP and Pt Ar4TBP are centered at 773 and 772 nm respectively. The PL spectra for Pt DPTBP and Pt Ar2TBP are slightly blue shifted (770 nm) and have a narrower full width at half maximum (FWH M) due to the increased planarity of the TBP macrocycle. The T1 lifetimes for the entire series were measured by transient absorption spectroscopy. The values for Pt TPTBP and Pt Ar4TBP as expected gave very similar T1 lifetime s of 29.9 and 32.0 s respect ively T he QYs should be very similar as they are directly proportional to the lifetimes. The QYs were measured relative to ZnTPP (0.04) in toluene for Pt TPTBP and Pt Ar4TBP to give values of 0.46 and 0.44 respectively. This is in good agreement with the lifetime data and reported values .57 However the lifetime and QY measured for Pt DPTBP was not expected based on the recent trend observed in the PdTBPs reported by Vinogradov et al discussed herein elsewhere. The T1 life time ( 28.0 s) and phosphorescence QY (0.40) for Pt DPTBP are nearly identical to Pt TPBP and Pt Ar4TBP. The QY was expected to increase (~double) due to the increased macrocycle planarity and reduction of the nonradiative decay rate (Table 38) However other lit erature reports exist suggesting that the rotation of the meso phenyl substituent serves as a nonradiative decay path way negating the effects of increased planarity .43, 78 Once this rotation is block ed (i.e. bulky group) the observed T1 lifetime increases as in the case of Pt Ar2TBP (53.0 s) The QY for Pt Ar2TBP (0.65) has been measured as high as 0.90 but difficulty exists in reproducing this measurement. A decrease in the nonradiative decay rate ( knr) from

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121 the increased pla narity is observed (Table 38). Pt Ar2TBP has the highest PL efficiency ever reported for a phosphor in this wavelength region. Table 3 8 Deactivation rate constants for T1 state of series 2 platinum TBPs in deox y genated toluene. Radiative decay rate constant ( kr), calculated as kr = phosk, and the nonradiative decay rate constant ( knr = kic + kisc), calculated as kr = k knr. Platinum Porphyrins k = 1/ T T (s1) kr (s1) knr (s1) T T Pt TPTBP 3.3 x 10 4 1.5 x 10 4 1.8 x 10 4 29.9 Pt Ar 4 TBP 3.1 x 10 4 1.4 x 10 4 1.8 x 10 4 32.0 Pt DPTBP 3.6 x 10 4 1.4 x 10 4 2.1 x 10 4 28.0 Pt Ar 2 TBP 1.9 x 10 4 1.2 x 10 4 6.5 x 10 3 53.0 Series 2PLED Device Results PLEDs were fabricated by sp in coating the active layer on top of a PEDOT:PSS layer, followed by evaporati on of the metal electrode materials to give the following device structure: glass/ITO/PEDOT:PSS(40 nm)/2% Pt porphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al Due to the limited solubility of Pt DPTBP it was excluded from device fabrication. Electro luminescence from the PLEDs is centered at ~770 nm with no host emission observed (Figure 316A). Light emission from the PLEDS turns on at an applied voltage of ~12 V observed in Figure 3 16C. Overall the PLEDs operate at relatively high voltages due to t he thickness of the emissive layer (110 nm) and the high electron and hole injection barriers. The PLEDs exhibit maximum radiant emittance of approximately 1000 W/cm2 (Figure 3 16C). The maximum external quantum efficiencies for the series range from 1.01.5%. The PLED fabricated from Pt TPTBP gave the highest EQE (1.50%) while Pt Ar4TBP gave a slightly lower EQE of 1.05%.

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122 Although Pt Ar2TBP has a much higher sol ution phosphorescence quantum yield the PLED EQE is slightly lower (1.43%) than that of Pt TPTBP. Wavelength (nm) 600 700 800 900 1000 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Voltage (V) 0 5 10 15 20 25 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 A B Voltage (V) 5 10 15 20 25 R ( W/cm 2 ) 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 C J (mA/cm 2 ) 1e-1 1e+0 1e+1 1e+2 EQE (%) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 D Figure 316. PLED device results for series 2 platinum TBPs Pt TPTBP (black), Pt Ar4TBP (red), and Pt Ar2TBP (green) with the following device structure: glass/ITO/PEDOT:PSS(40 nm)/2% Ptporphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al A) EL spectra, B) JV plot, C) R V plot, D) External quantum efficiency. Series 2OLED Device Results Multilayer OLEDs were fabricated f rom thermal vapor deposit ion to give the following device structure: glass/ ITO/NPB(40 nm)/Alq3:4% Pt TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/Al for series 2 platinum TBPs. Electroluminescence from the OLEDs is centered at ~770 nm and is shown in Figure 317A. Light emission is observed at a

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123 rather low turn on voltage of ~2 V with the maximum radi a nt emittance of 1 mW/cm2 obtained at ~12V (Figure 3 17B) The current densities across the series are similar and expected due to little difference in the device structure with the only changes coming from substituent patterns in the platinum TBPs (Figure 317B). Voltage (V) 0 2 4 6 8 10 12 14 J (mA/cm 2 ) 1e-8 1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 R (mW/cm 2 ) 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 Wavelength (nm) 600 700 800 900 1000 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 P (mW/W) 0 10 20 30 40 50 60 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 EQE (%) 0 2 4 6 8 10 A B C D Figure 317. OLED device results for series 2 platinum TBPs. Pt TPTBP (black), Pt Ar4TBP (red), Pt DPTBP (green), and Pt Ar2TBP (blue) with device structure: glass/ITO/NPB(40 nm)/Alq3:4% Pt TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/Al. A) EL spectra for OLEDs, B) JV plot (closed circles) and R V (open circles), C) Power efficiency, D) External quantum efficiency. The EQE data shown in Figure 317C for the series follows a different trend than the PLED EQE data. In contrast to the PLED data, Pt Ar4TBP gave a higher maximum EQE (9.2%) than Pt TPTBP (8.0%). Although Pt DPTBP was not soluble enough for PLED fabrication it was readily incorporated into a multilayer OLED giving a maximum

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124 EQE of 5.0%. The significantly lower efficiency is likely due to bimolecular interactions or aggregates of Pt DPTBP within the host matrix. Interestingly the T1 lifetime s and phosphorescence QYs for Pt TPTBP, Pt Ar4TBP and Pt DPTBP are nearly identical. Howeve r these materials give maximum OLED EQEs ranging from 5.09.2%. The differences in efficiency are likely due to some physical property of the porphyrin or porphyrin: host morphology. Thompson et al have shown that platinum porphyrins with high phosphores cence QYs like Pt OEP (0.45) give higher maximum EQEs (1.3%) in OLEDs compared to Pt DPP (0.16, 0.25%).43 However, despite the significant increase in the solution QY for Pt Ar2TBP the maximum EQE (7.8%) is comparable to that of Pt TPTBP (8.0%). Series 3Photophysical Properties The EQE data for series 2 OLEDs strongly suggest some form of aggregation of the phosphor or phosphor: host incompatibility from a morphology standpoint Recent literature reports of both porphyrin systems and other dyes have displayed improvement in device efficiencies through the addition of bulky substituents.69, 71, 73, 77, 78 This create s a dye encapsulation effect that prevents self quenching mechanisms. The platinum TBPs in series 3 were designed in order to examine the effects of bulky substituents on the photophysical properties and device efficienc ies shown and are shown Figure 3 18. The absorption and photoluminescence in air saturated toluene for series 3 freebase TBPs is shown in Figure 319. The absorption and emission wavelength maxima for series 3 freebase TBPs are summarized in Table 39 along with the molar absorption coeffi cients, QYs and S1 lifetimes. The Soret and Q band for H2ArF4TBP are each red shifted about 10 nm and they resemble the absorption spectrum for H2TPTBP.

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125 Figure 318. Structures of free base and platinum complexes for series 3 TBPs This trend is simila r to the reported H2TPP and H2TPP Fluorenyl derivatives .77 Aside from the red shift in the Soret and Q band the addition of the fluorenyl substituents contributes to an additional absorption at ~30 0 nm The Soret bands for H2TAr2TBP and H2Ar2OPrTBP both display a small red shift of 2 and 5 nm respectively relative to H2DPTBP. The Q bands however are not red shifted and identical to H2DPTBP. The mo lar absorptivity values measured for series 3 free-b ase TBPs are in line with the values obtained for series 2. The PL spectra in air saturated toluene are shown in Figure 319. The emission maxima for H2ArF4TBP is red shifted 7 nm relative to H2TPTBP. The lower energy band is also significantly higher in intensity than in H2TPTBP (Appendix A 6). This suggests the fluorenyl substituents are increasing the saddling of the TBP macrocycle leading to the observed shorter lifetime. Consequently a smaller quantum yield relative to

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126 H2TPTBP would be expected howev er the increase is probably attributed to a reduction in solution interactions similar to the reported TPP derivatives.77 Table 3 9 Photophysical properties of Series 3 freebase TBPs in air saturated toluene. The fluorescence quantum yield for H2ArF4TBP was measured relative to ZnTPP (0.04) with excitation at 420 nm in toluene. The fluorescence quantum yield for H2T Ar2TBP and H2Ar2OPrTBP was measured relative to H2Ar2TBP (0.3 8) with excitation at 420 nm in toluene The S1 decays were obtained by single photon counting method. Freebase Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 cm 1 ) Fluorescence max nm fl fl (ns) H2ArF4TBP 474, 642 474 = 3.03 x 105 642 = 3.63 x 10 4 711, 788 6.0% 0.4 2.8 H2TAr2TBP 442, 612 442 = 3.43 x 105 612 = 5.68 x 10 4 670, 735 39% 1 10.4 H2Ar2OPrTBP 445, 625 445 = 3.22 x 105 625 = 7.23 x 10 4 674, 743 43% 3 10.6 Table 3 10. Deactivation rate constants for S1 state of series 3 freebase TBPs in air saturated toluene. Radiative decay rate constant ( kr), calculated as kr = flk, and the nonradiative decay rate constant ( knr = kic + kisc), calculated as kr = k knr. Freebase Porphyrins k = 1/ fl (s1) kr (s1) knr (s1) fl (ns) H 2 ArF 4 TBP 3.6 x 10 8 2.1 x 10 7 3.4 x 10 8 2.8 H 2 TAr 2 TBP 9.6 x 10 7 3.8 x 10 7 5.8 x 10 7 10.4 H 2 Ar 2 OPrTBP 9.4 x 10 7 4.1 x 10 7 5.4 x 10 7 10.6 The fluorescence QY and S1 lifetime for H2TAr2TBP and H2Ar2OPrTBP are identical to that of H2Ar2TBP. Replacing the tert butyl substituents on the meso aryl substituents of H2Ar2TBP with 4 tert butylphenyl to give H2TAr2TBP has shown to reduce solution interactions thus increasing the QY in TPP derivatives but was not

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127 expected to significantly i ncrease the QY, but may prevent aggregation in solid state films.77 The choice of the propyl substituents in H2Ar2OPrTBP was determined from X ray crystallography data reported for freebase 5,15d iaryl porphyrins in efforts to interrupt the dominant offset stacking in the crystal structures.123 The emission maxima for H2TAr2TBP (670 nm) is identical to H2DPTBP. The PL spectrum of H2Ar2OPrTBP is red shifted ~4 n m and it is unclear if this is from an inductive effect from the propyl groups or an out of plane distortion of the macrocycle. 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength (nm) 300 400 500 600 700 800 900 Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 A B C Figure 319. Normalized absorption (black) and photoluminescence (red) for series 3 free base TBPs in air saturated toluene: A) H2ArF4TBP, B) H2TAr2TBP, C) H2Ar2OPrTBP.

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128 The absorption and photoluminescence in deoxygenated toluene for series 3 platinum TBPs is shown in Figure 320 The photophysical data for series 3 platinum TBPs is summarized and reported in T able 311. The rad iative and nonradiative rates were calculated and shown in Table 312. The Soret and Q band for Pt ArF4TBP are red shifted 8 and 5 nm respectively with similar molar absorptivity constants compared to PtTPTBP. The absorption spectrum for Pt TAr2TBP is nearly identical to Pt DPTBP and Pt Ar2TBP. T he Soret band for Pt Ar2OPrTBP has a small red shift of 1 nm relative to Pt Ar2TBP. A larger red shift is observed in the Q band of ~20 nm. The molar absorptivity constants for Pt TAr2TBP and Pt Ar2OPrTBP are in line with the Pt diaryl TBPs from series 2. Table 3 11. Photophysical data for series 3 platinum TBPs in deoxygenated toluene. Quantum yields were measured relative to ZnTPP (0.04) by excitation at 420 nm in toluene. The triplet lifetimes were obtained by transient absorption spectroscopy. Platinum Porphyrins Absorption max (Soret, Q band) nm ( max = M 1 cm 1 ) Phosphorescence max nm phos T T Pt ArF4TBP 438, 617 438 = 2.22 x 105 617 = 1.13 x 10 5 772 34% 1 20.1 Pt TAr2TBP 411, 605 411 = 2.15 x 105 605 = 1.67 x 10 5 769 58% 3 51.7 Pt Ar2OPrTBP 411, 625 411 = 2.06 x 105 614 = 1.47 x 10 5 786 60% 1 51.8 The absorption and photoluminescence in deoxygenated toluene for series 3 platinum TBPs is shown in Figure 320. The emission maximum for Pt ArF4TBP is centered at 772 nm. The T1 lifetime of 20.1 s for Pt ArF4TBP is significantly shorter than that of PtTPTBP and Pt Ar4TBP. This leads to the expected decrease in the

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129 phosphorescence QY (0.341) relative to PtTPBP and Pt A r4TBP. The nonradiative decay rate constant for Pt ArF4TBP is doubled compared to Pt TPTBP. Although no significant red shift is observed in either the absorption or PL for Pt ArF4TBP the increase in knr still suggests nonplanar distortions are likely the reason. Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength (nm) 0.0 0.2 0.4 0.6 0.8 1.0 400 600 800 1000 0.0 0.2 0.4 0.6 0.8 1.0 A B C Figure 320. Normalized absorption (black) and photoluminescence (red) for series 3 platinum TBPs in toluene: A) Pt ArF4TBP, B) Pt TAr2TBP, C) Pt Ar2OPrTBP. The emission maximum for Pt TAr2TBP of 769 nm is blue shifted 1 nm relative to Pt Ar2T BP. Similar to H2Ar2OPrTBP, the emission maximum for Pt Ar2OPrTBP of 786 nm is red shifted 16 nm relative to Pt Ar2TBP. The T1 lifetimes for PtTAr2TBP and Pt -

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130 Ar2OPrTBP of 51.7 and 51.8 s are very close to those of Pt Ar2TBP (53.0 s) measured by transien t absorption spectroscopy. Consequently, the QYs should be very similar as they are directly proportional to the lifetimes but are difficult to accurately measure. The reported trend by Vinogradov et al of the QY doubling from Pd TPTBP to Pd DPTBP is suppo rted by other literature data. Since the emission from platinum and palladium porphyrins is largely porphyrin based ( *) this trend should also hold true for Pt Ar2TBP, Pt TAr2TBP, and Pt Ar2OPrTBP.124, 125 Table 3 12. Deactivation rate constants for T1 state of series 3 platinum TBPs in deoxygenated toluene. Radiative decay rate constant ( kr), calculated as kr = phosk, and the nonradiative decay rat e constant ( knr = kic + kisc), calculated as kr = k knr. Platinum Porphyrins k = 1/ T T (s1) kr (s1) knr (s1) T T Pt ArF 4 TBP 5.0 x 10 4 1.0 x 10 4 4.0 x 10 4 20.1 Pt TAr 2 TBP 1.9 x 10 4 1.1 x 10 4 8.1 x 10 3 51.7 Pt Ar 2 OPrTBP 1.9 x 10 4 1.2 x 10 4 7.8 x 10 3 51.8 Series 3PLED Device Results PLEDs were fabricated in an identical manner to those in series 2, by spincoating the active layer on top of a PEDOT:PSS layer, followed by evaporation of the metal electrode materials to give the following device structure: glass/ITO/PEDOT:PSS(40 nm)/2% Pt porphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al. Electroluminescence from PLEDs fabricated from Pt ArF4TBP and Pt TAr2TBP is centered at ~775 nm shown in Figure 321A. The PLED fabricated from Pt Ar2OPrTBP exhibits an electroluminescence maximum at 790 nm, red shifted similar to the PL emission. No host emission is observed in each device with light emission from the phosphors turning on at applied voltages (~12 V) identical to series 2 (Figure 321C).

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131 Wavelength (nm) 600 700 800 900 1000 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 A Voltage (V) 0 5 10 15 20 25 J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 B Voltage (V) 5 10 15 20 25 R ( W/cm 2 ) 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 C J (mA/cm 2 ) 1e-1 1e+0 1e+1 1e+2 EQE (%) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 D Figure 321. PLED device res ults for series 3 platinum TBPs with the following device structure: glass/ITO/PEDOT:PSS(40 nm)/2% Ptporphyrin:PVK:PBD(7:3) (110 nm)/LiF(1 nm)/Ca(10 nm)/Al. Pt ArF4TBP (black), Pt TAr2TBP (red), and P t Ar2OPr TBP (green). A) EL spectra for PLEDs, B) JV plot, C) R V plot, D) External quantum efficiency. The PLEDs exhibit maximum radiant emittance of approximately 1.61.8 m W/cm2 (Figure 3 21C). The maximum EQEs for the series range from 1.2 1.7 %. The PLED fabricat ed from Pt ArF4TBP gave the highest EQE (1.7 %) slightly higher than Pt TPTBP (1.5%). Pt T Ar2TBP and Pt Ar2OPrTBP both have significantly higher phosphorescence QYs compared to Pt TPTBP and Pt ArF4TBP but no significant gain is observed in devi ce efficiency. The maximum EQE for Pt TAr2TBP and Pt Ar2OPrTBP are 1.5 and 1.2 % respectively. Comparison of series 2 and 3 PLEDS from platinum TBPs with similar so lution QYs and lifetimes give the following trends with respect to the maximum

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132 EQE data: PtA rF4TBP > Pt TPTBP > Pt Ar4TBP and Pt TAr2TBP > Pt Ar2TBP > Pt Ar2OPrTBP. The two major conclusions can be drawn from the observed trend. The frist is that despite the increased solution QYs of the platinum diaryl TBPs large increases are not observed in de vice efficiency. This is likely due to bimolecular interactions that lead to self quenching pathways. The second, is that the addition of bulky substituents in the meso aryl positions lead to small to moderate increases in device efficiency demonstrating t hat the substituents have little affect on the porphyrin:host polymer morphology. Series 3OLED Device Results Multi layer OLEDs were fabricated by thermal vapor deposition of Pt TAr2TBP and Pt Ar2OPrTBP to give the following device structure: glass/ ITO/ NPB(40 nm)/Alq3:4% Pt TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/Al. Thermal vapor deposition was not attempted due to the high molecular weight of Pt ArF4TBP. Electroluminescence from the OLEDs for Pt TAr2TBP and Pt Ar2OPrTBP is centered at 775 and 790 nm respect ively and is shown in Figure 322A. Turn on voltages of ~2 V and maximum radiant emittance of 1 mW/cm2 obtained at ~12V are in line with the data from series 2 OLEDs (Figure 322B). The current densities from the JV plot for both devices are similar and expected due to the identical device structure (Figure 3 22 B). The EQE data shown in Figure 322D for both devices follows a different trend than the PLED EQE data. Pt TAr2TBP exhibits a lower maximum EQE (3.2%) than Pt Ar2OPrTBP (6.9%). While Pt TAr2TBP a nd Pt Ar2OPrTBP have identical solution photophysics as Pt Ar2TBP the overall OLED EQEs range from 3.27.8%. The variations in performance are not well understood and likely originate from some physical property of the porphyrin:Alq3 films. The observed tr end demonstrates that the

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133 additional substituents have a negative impact on the device efficiency. In the case of Pt TAr2TBP the maximum EQE is two times lower than that of the Pt Ar2TBP based OLED. This suggests that the additional substituents in Pt TAr2TBP and Pt Ar2OPrTBP do not enhance mixing with the host (Alq3) or prevent bimolecular quenching pathways. Wavelength (nm) 600 700 800 900 1000 Normalized EL 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Voltage (V) 0 2 4 6 8 10 12 14 16 J (mA/cm 2 ) 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 R (mW/cm 2 ) 1e-8 1e-7 1e-6 1e-5 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 A B J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 P (mW/W) 0 10 20 30 40 50 60 C J (mA/cm 2 ) 1e-4 1e-3 1e-2 1e-1 1e+0 1e+1 1e+2 1e+3 EQE (%) 0 2 4 6 8 10 D Figure 322. OLED device results for series 3 platinum TBPs PtTAr2TBP (black), Pt Ar2OPr TBP (red) with device structure: glass/ ITO/NPB(40 nm)/Al q3:4% Pt TBP(25 nm)/Bphen(80 nm)/LiF(1 nm)/Al. A) EL spectra for PLEDs, B) JV plot (closed circles) and R V plot (open circles), C) Power efficiency, D) External quantum efficiency. Conclusion Electroluminescent OLEDs and PLEDs have been prepared by thermal vapor deposition with small molecule hosts and solution blending with polymers respectively

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134 for each series of extended platinum porphyrins The device wavelengths of the near IR electroluminescence range from 770 to 1005 nm based on the extended platinum porphyrin system used. OLEDs have been prepared with record efficiencies of 9.2% and 3.8% at 770 and 898 nm respectively. In general, as the wavelength increases a decrease in overall device efficiency is observed for both PLEDs and OLEDs in accord with the energy gap law. Unexpectedly devices fabricated using phosphors with sign ificantly larger PL efficiency did not directly translate into higher device efficiency Lar ge ranges in device efficiency for phosphors with similar photophysical properties suggest a physical property of the platinum porphyrin in the solid state or a porphyrin:host morphology plays a major role in device efficiency. Experimental Optical Characterization Absorption spectra for all freebase and platinum extended porphyrins were measured using a PerkinElmer Lambda 25 UV vis spectrometer. The PL spectra were obtained by excitation at the Soret band absorption maximum for each compound. The spectra were recorded with an ISA Spex Triax 180 spectrograph coupled to a Spectrum 1 liquid nitrogen silicon charge coupled device detector. This spectrometer has a relatively flat spectral response to 900 nm, although there is some loss in efficiency due to the grating, which is blazed in the visible region. The PL for Pt Ar4TAP was measured separately on a PTI fluorimeter equipped with InGaAs near IR detector and a Spex Fluorolog II equipped with InGaAs near IR detector. The solution fluorescence and phosphorescence quantum yields were calculated relative to ZnTPP in toluene (0.04) unless otherwise noted according to a previously described method.117 126 The sample and actinometer solutions had matched optical density at a shared excitation wavelength. The emission spectra were corrected

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135 for the spectrometer response prior to being used to compute the quantum yield. Timeresolved transient absorption spectra for extended platinum porphyrins in toluene were collected by using previously described laser systems for the visible and near IR regions.127 Device Fabrication and Characterization. PLEDs were fabricated by Ken Graham from the Reynolds group at the University of Florida using the following method. PLEDs were fabricated on prepatterned indium tin oxide (ITO) coated glass substrates with a sheet resistance of ~20 / The ITO substrates were cleaned sequentially with a sodium dodecyl sulfate solution, acetone, and isopropyl alcohol followed by exposure to an oxygen plasma. A layer of PEDOT:PSS (Baytron P VP Al4083) was spincoated on the ITO immediately following oxygen plasma exposure and then annealed at 120 C under vacuum for 2 h. The active layer solutions consisting of varying weight percentages of extended platinum porphyrins in PVK:PBD were prepared and spincoated from chlorobenzene in an MBraun glovebox w ith <0.1 ppm oxygen and water. The cathode consisting of LiF (1 nm), Ca (10 nm), and Al (80 nm) was deposited in a thermal evaporator under a vacuum of 106 Torr. Radiant emittance ( R ) voltage (V) measurements were carried out using a calibrated UDT Instruments silicon detector. Current density ( J) voltage (V) measurements were carried out using a Keithley 2400 sourcemeter. The electroluminescence (EL) spectra were collected using the ISA SPEX Triax 180 spectrograph or a Spex Fluorolog II equipped with InGaAs near IR detector with the devices driven using the Keithley sourcemeter. Each 2.5 x 2.5 cm substrate features eight independently addressable pixels with area 0.07 cm2, and the results presented herein represent measurements averaged over three pixels.

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136 The OLEDs were fabricated by Yixing Yang in Dr. Xues group D epartment of Materials Science at the University of Florida. The OLEDs were fabricated on glass substrates commercially coated with an ITO anode with a sheet resistance of ~20 / The substrates were cleaned in ultrasonic baths of deionized water, acetone, and isopropyl alcohol consecutively for 15 min each and then exposed to an ultraviolet ozone environment for 15 min immediately before loading into a high vacuum chamber (bas e pressure ~107 Torr) All the layers including the cathode, were deposited using vacuum thermal evaporation following procedures published previously.128 The thicknesses o f the HTL and EML were 40 and 20 nm, respectively, whereas the ETL layer thickness was 100 nm, optimized to achieve the highest device efficiencies. A 1 nm layer of LiF followed by a 100 nm Al layer was then deposited as the cathode. Radiant emittance ( R ) current density ( J) voltage (V) characteristics were measured under ambient conditions using an Alilent 4155C semiconductor parameter analyzer and a calibrated Newport silicon detector. The EL spectra were collected as described above, with the device driv en at a constant current. The radiant emittance for both OLEDs and PLEDs was calibrated assuming Lambertian emission, and the EQE and electrical to optical power efficiency values were derived on the basis of the recommended methods.129 Each 2.5 x 2.5 cm substrate features four independently addressable pixels with area 4mm2, and the results presented herein represent measurements averaged over at least eight pixels.

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137 CHAPTER 4 CONCLUSIONS The previous chapters detail the investigation of extended platinum porphyrins as near IR phosphors for us e in near IR LED applications. Reported are the synthesis, characterization and photophysical properties wi th the PLED and OLED device data for three novel series of extended platinum porphyrins. The photophysical properties of porphyrins make them excel lent candidates for use in LED applications due to their narrow emission. The use of phosphors over fluorophores has been shown to give theoretical device efficiencies of a 100%. Therefore high efficiency devices can only be achieved with materials that posses phosphorescence quantum yields approaching unity. The insertion of a transition metal such as palladium or platinum forming a metalloporphyrin induces intersystem crossing to g ive phosphors with high phosphorescence quantum yields that are ideal candi dates for LED applications. The photophysical properties of porphyr ins with fusedbenzo rings have long been of interest with the platinum complexes of this class of porphyrins almost completely absent from the literature. Herein is the first full report of the photophysical properties for extended platinum porphyrins. The high PL efficiencies of the platinum complexes for TBP, TNP and TAP systems make them ideal choices for near IR phosphors. OLEDs and PLEDs have been fabricated in order to demonstrate the application of these materials i n near IR LEDs. Conclusions and Future work The synthetic work and photophysical characterization for each series with the reported PLED and OLED device data has significantly advanced the field of near IR LEDs based upon the use of extended platinum porphyrins a near IR phosphors The advancements from series 1 include

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138 devic es with EL reaching further into the near IR (900 and 100 0 nm) while also achieving new device efficiency records for each new wavelength region. The preparation and characterization of series 2 platinum TBPs produced the brightest platinum TBP ever reported. This record quantum yield expands farther than platinum TBPs and is the highest known for this wavelength region of any reported material. The structures designed for series 3 platinum TBPs attempted to prevent quenching mechanisms in the device from porphyrinporphyrin interactions through chemical modification of the porphyrin macrocycle. This series represents some of the most complex TBPs reported to date while also furthering the understanding of substituent effects on the photophysical properties on the TBP macrocycle. While th is body of work has answered many questions concerning the use of extended platinum porphyrins for near IR LED applications it has also raised many more. The large increase in the solution quantum yield observed in series 2 did not directly translate into significantly higher device EQEs This result along with the dev ice data from series 3 platinum TBPs suggest that the translation of solution photophysical properties to the solid state for these novel phosphors is not well understood. Future work should be directed towards gaining an understanding of how these materials behave in the solid state. A clear understanding of the solid state photophysical properties is necessary to completely achieve optimized device efficiencies I t would also be advantageous to thoroughly examine the photophysical properties as a function of concentration in a select variety of host materials. The device data for series 2 and 3 shows significant variations for materials with identical solution photophysical properties. This strongly suggest a physical property or unique morphology exist

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139 between the phosphor and host material ultimately contributing to an increase or decrease in device efficiency. The investigation and answers to these questions may provide the data necessary to utilize the record quantum yield of near IR phosphors like Pt A r2TBP achieving much higher device efficiencies.

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140 A PPENDIX A FIGURES 0 5000 10000 15000 20000 25000 30000 35000 0 20 40 60 0 5000 10000 15000 20000 25000 30000 35000 CPSTime (ns) 0 20 40 60 A B C D Figure A 1. Fluorescence lifetimes for Series 1 freebase extended porphyrins in air saturated toluene: A) H2TPTBP, B) H2TPTNP, C) H2Ar4TNP(OMe)8, D) H2Ar4TAP.

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141 400 500 600 700 800 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 400 500 600 700 800 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 400 500 600 700 800 -0.20 -0.15 -0.10 -0.05 0.00 Absorbance 400 500 600 700 800 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 A B C D Figure A 2. T1Tn absorption data for series 1 extended platinum porphyri ns in deoxygenated toluene: A) Pt TPTBP, B) Pt TPTNP, C) Pt Ar4TNP(OMe)8, D) Pt Ar4TAP.

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142 0 5000 10000 15000 20000 25000 30000 0 10 20 30 40 50 60 0 10 20 30 40 50 60 0 5000 10000 15000 20000 25000 30000 CPSTime (ns)A B C D Figure A 3 Fluorescence lifetimes for Series 2 freebase extended TBPs in air saturated toluene: A) H2T PTBP, B) H2DPTBP, C) H2Ar4TBP, D) H2Ar2TBP.

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143 400 500 600 700 800 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 400 500 600 700 800 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 400 500 600 700 800 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 400 500 600 700 800 -0.04 -0.02 0.00 0.02 0.04 0.06 0.08 AbsorbanceWavelength (nm)A B C D Figure A 4. T1Tn absorption data for series 2 extended platinum TB Ps in deoxygenated toluene: A) Pt TPTBP, B) Pt Ar4TBP, C) Pt DPTBP, D) Pt Ar2TBP.

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144 0 5000 10000 15000 20000 25000 30000 35000 0 20 40 60 0 5000 10000 15000 20000 25000 30000 35000 CPSTime (ns) 0 20 40 60 A B C Figure A 5. Fluorescence lifetimes for Series 3 free base extended TBP s in air saturated toluene: A) H2ArF4TBP, B) H2TAr2TBP, C) H2Ar2OPrTBP.

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145 Wavelength (nm) 300 400 500 600 700 800 900 Normalized Intensity 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Figure A 6 Normalized abs orption and PL of H2TPTBP (black and red) and H2ArF4TBP (green and blue) in air saturated toluene.

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146 400 500 600 700 800 Absorbance -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 Wavelength (nm) 400 500 600 700 800 -0.05 0.00 0.05 0.10 400 500 600 700 800 -0.15 -0.10 -0.05 0.00 0.05 A B C Figure A 7. T1Tn absorption data for series 3 extended platinum TBPs in deoxygenated toluene: A) Pt ArF4TBP, B) Pt TAr2TBP, C) Pt Ar2OPrTBP.

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147 Eem (0,0) in eV 1.1 1.2 1.3 1.4 1.5 1.6 1.7 ln( knr) e9e10e11e12e13 Figure A 8. Plot of the natural log of the nonradiative decay constant ( knr) and the emission maximum in eV (Eem) for series 1 exte nded plantium porphyrins.

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148 A PPENDIX B NMR SPECTRA Figure B 1. 1H NMR (300 MHz, CDCl3) spectrum of 6 Figure B 2 1H NMR (300 MHz, CDCl3) spectrum of 1 7 b

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1 49 Figure B 3 1H NMR (300 MHz, CDCl3) spectrum of 18 b Figure B 4 1H NMR (300 MHz, pyridin e d5) spectrum of 3 9b

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150 Figure B 5 1H NMR (5 00 MHz, pyridined5) spectrum of 3 9c. Figure B 6 1H NMR (5 00 MHz, pyridined5) spectrum of 40b

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151 Figure B 7 1H NMR (500 MHz, pyridine d5) spectrum of 42 Figure B 8 1H NMR ( 500 MHz, pyridined5) spectrum of 45c

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152 Figure B 9 1H NMR ( 500 MHz, pyridined5) spectrum of 45d Figure B 10. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 39b

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153 Figure B 11. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 39c Figure B 12. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 40a

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154 Figure B 13. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 40b Figure B 14. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 42.

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155 Figure B 15. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 45b Figure B 1 6 1H NMR (500 MHz, p yridine d5) spectrum of Pt 45c

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156 Figure B 17. 1H NMR (500 MHz, pyridine d5) spectrum of Pt 45d

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157 L IST OF REFERENCES 1. J. M. Olson, "Photosynthesis in the Archean Era," Photosynth. Res. 88, 109 117 (2006). 2. R. A. Sheldon, Metalloporphyrins in Catalytic Oxidations (Marcel Dekker, Inc., New York, 1994). 3. J. A. Milroy, "Observations on some metallic compounds of hematoporphyrin," Biochem. J. 12 (1918). 4. H. Fischer and K. Zeile, "Porphyrin syntheses. XXII. Syntheses of hem atoporphyrin, protoporphyrin and hemin," Justus Liebigs Ann. Chem. 468 98116 (1929). 5. H. Fischer and H. Orth, Die Chemie des Pyrrols, Vol. I III. (Akademische Verlagsgesellschaft, Leipzig, 19341940). 6. H. B. F. Dixon, A. Cornish Bowden, C. Liebecq, K L. Loening, G. P. Moss, J. Reedijk, S. F. Velick, P. Venetianer and J. F. G. Vliegenthart, "Nomenclature of tetrapyrroles," Pure Appl. Chem 59 779832 (1987). 7. K. M. Smith, "Strategies for the Synthesis of Octaalkylporphyrin Systems," in The Porphyrin Handbook Vol. 1, edited by K. M. Kadish, K. M. Smith and R. Guilard (Academic Press, San Diego, 2000), pp. 240. 8. R. B. Woodward, W. A. Ayer, J. M. Beaton, F. Bickelhaupt, R. Bonnett, P. Buchschacher, G. L. Closs, H. Dutler and et al "The total synthesis of chlorophyll," J. Am. Chem. Soc. 82 38003802 (1960). 9. J. S. Lindsey, "Synthesis of meso Substituted Porphyrins," in The Porphyrin Handbook Vol. 1, edited by K. M. Kadish, K. M. Smith and R. Guilard (Academic Press, San Diego, 2000), pp. 4680. 10. P. Rothemund, "Formation of porphyrins from pyrrole and aldehydes," J. Am. Chem. Soc. 57 20102011 (1935). 11. P. Rothemund, "New porphyrin synthesis. Synthesis of porphin," J. Am. Chem. Soc. 58 625627 (1936). 12. P. Rothemund and A. R. Menotti, "P orphyrin studies. IV. The synthesis of tetraphenylporphine," J. Am. Chem. Soc. 63 267270 (1941). 13. A. D. Alder, F. R. Longo and W. Shergalis, "Mechanistic investigation of porphyrin synthesis. I. Preliminary studies on ms tetraphenylporphyrin," J. Am. Chem. Soc. 86 31453149 (1964).

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158 14. A. D. Alder, F. R. Longo, J. D. Finarelli, J. Goldmacher, J. Assour and L. Korsakoff, "A simplified synthesis for mesotetraphenylporphine," J. Org. Chem. 32, 476 (1967). 15. D. Dolphin, "Porphyrinogens and porphodimethenes, intermediates in the synthesis of m tetraphenylporphins from pyrroles and benzaldehydes," J. Heterocycl. Chem. 7 275 283 (1970). 16. J. S. Lindsey, H. C. Hsu and I. C. Schreiman, "Synthesis of tetraphenylporphyrins under very mild conditions ," Tetrahedron Lett. 41, 49694970 (1986). 17. J. S. Lindsey, I. C. Schreiman, H. C. Hsu, P. C. Kearney and A. M. Marguerettaz, "Rothemund and Alder Long reactions revisited: synthesis of tetraphenylporphyrins under equilibrium conditions," J. Org. Chem. 5 2 827836 (1987). 18. L. Edwards, M. Gouterman and C. B. Rose, "Synthesis and vapor spectrum of Zinc tetrabenzoporphine," J. Am. Chem. Soc. 98, 76387641 (1976). 19. M. Gouterman, "Spectra of porphyrins," J. Mol. Spectrosc. 6 (1961). 20. L. Bajema, M. Gouterman and C. B. Rose, "Porphyrins. XXIII. Fluorescence of the second excited singlet and quasiline structure of zinc tetrabenzoporphine," J. Mol. Spectrosc. 39 421 431 (1971). 21. C. E. Dent, R. P. Linstead and A. R. Lowe, "Phthalocyanines. VI. The struc ture of the phthalocyanines," J. Am. Chem. Soc., 10331039 (1934). 22. P. A. Barrett, R. P. Linstead, F. G. Rundall and G. A. P. Tuey, "Phthalocyanines and related compounds. XIX. Tetrabenzoporphine, tetrabenzomonazaporphine, and their metallic derivatives ," J. Am. Chem. Soc. (1940). 23. P. A. Barrett, R. P. Linstead, J. J. Leavitt and G. A. Rowe, "Phthalocyanines and related compounds. XVIII. Intermediates for the preparation of tetrabenzoporphines: the Thorpe reaction with phthalonitrile.," J. Am. Chem. S oc. (1940). 24. A. Vogler and H. Kunkely, "Simple template synthesis of zinc tetrabenzoporphyrin.," Angewandte Chemie 90 808 (1978). 25. V. N. Kopranenkov, E. A. Makarova and E. A. Luk'yanets, "New approach to the synthesis of metallic complexes of tetrab enzoporphines," Zh. Obshch. Khim. 51, 27272730 (1981). 26. D. E. Remy, "A versatile synthesis of tetrabenzoporphyrins," Tetrahedron Lett. 24, 14511454 (1983).

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168 BIOGRAPHICAL SKETCH Jonathan R. Sommer was born in Cheboygan, Michigan, and grew up in Orange Park, Florida, a suburb of Jacksonville. He spent the majority of his childhood outside fishing and playing sports such as football and basketball. Jonathan continued playing football while at Orange Park High School growing mentally and physically from the coaching and mentorship of Coach Bill Shields and Roy Clayton. His college career started at Jacksonville University playing football for the Dolphins and studying chemistry. However, his deep affection for the tripleoption, which developed during his prep career led him to transfer to Georgia Southern University to play football under Head Coach Paul Johnson. Here he continue d working towards his Bachelor of Science in chemistry. He took a strong interest in both organic chemistry and quantum mechanics from working with his undergraduate research advisors Dr. Kurt Weigel and Dr. James LoBue He began his graduate studi es at the University of Florida under the guidance of Prof. Kirk S. Schanze which provided the opportunity to synthesis advanced materials and study their photophysical properties for materials science applications while pursuing a doctoral degree in organic chemistry.