TETRAPHENYLPORPHYRIN DIMERS AND THEIR DERIVATIVES by JESMAEL P. ^ZINGONI B.Sc, University of Zambia, 1975 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES in the Department of Chemistry We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA May, 1979 Ci^Jesmael P. Zingoni In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of , CMSTRY The University of British Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 iw is, 1979 (ii) ABSTRACT Tetraphenylporphine (TPP) and its para-methyl deri• vative have been synthesized by direct reaction of pyrrole with the corresponding aldehyde. The synthesis of two unsymmetrically substituted tetraarylporphyrins is re• ported. The compounds prepared are' 5-(^-hydroxypheny1) -10,15j20-tritolyIporphyrin and 5-(^-hydroxypheny1)-10, 15}20-triphenyIporphyrin. The sy thesis of covalently linked porphyrin dimers, joined via ether linkages, is described. High yields of the tetraaryIporphyrin dimers were obtained by the reac• tion of the bi-functionall,6-ditosyloxyhexane with phenolic porphyrins such as 5-(^-hydroxypheny1)-10,15,20-tritoly1-" porphyrin. The dimeric porphyrins were then chromatograph- ically separated from the unreacted monomericLporphyrins , The reduction of the porphyrins(monomers and dimers) has been carried out using the standard diimide precursor, p-toluenesulfonylhydrazine. We have been able to demon• strate that the most efficient chlorin preparation in• volves the diimide reduction of a tetraaryIporphyrin to the corresponding bacteriochlorin, followed by the ad• dition of the "high potential quinone" DDQ, to dehydro- genate the bacteriochlorin. A detailed study of the absorption spectra of these chlorins and bacteriochlo- rins was undertaken. Zinc metallo-derivatives of the porphyrins, chlorins and bacteriochlorins were prepared by the reaction of the free bases with zinc acetate in dry pyridine. (iii) An attempt was made to synthesize tetra-meso- [p, p ' - ( 3, 3 '-phenoxypropoxypheny1)]-s trati-bis porphyrin (Compound XX), a novel cyclophane system composed of two opposed, co-axial porphyrin rings, rigidly held together by peripheral ether linkages. The synthesis was attempted by construction of a second porphyrin ring on top of a pre-existing one, by way of the condensation of four pyrroles with a tetraaldehyde, derivative of tetraphenyl- porphyrin, under high dilution conditions. The last reaction step was unsuccessful. The structures and purity of the intermediate compounds leading to the strati-bis- porphyrin were established by mass spectroscopy and proton n.m.r. spectroscopy. (iv) ACKNOWLEDGEMENTS I would like to express my gratitude to my Research Advisor, Professor David Dolphin, for introducing me to the very important field of Porphyrin Chemistry. I would also like to thank all the students I know, who have been or are in Dr. Dolphin's research laboratories, for the useful chemical discussions we have engaged in. I would like to acknowledge the U.E.C. Chemistry Department for giving me the opportunity to teach. Barb, my wife, deserves special appreciation for general support and encouragements. (v) TABLE OF CONTENTS PAGE TITLE ' (1) 'ABSTRACT (ii) ACKNOWLEDGEMENTS ( iv ) ABBREVIATIONS ( ix ) STRUCTURE AND NOMENCLATURE (x) INTRODUCTION 1 DISCUSSION 29 CONCLUSIONS ^6 EXPERIMENTAL 50 PART (A) - SUBSTITUTED TETRAPHENYLPORPHYRINS - (MONOMERS AND DIMERS ) 52 meso-Tetraphenylporphyrin 52 meso-Tetratoly Iporphin 53 5_(^-Hydroxypheny1)-10 j15 j 2 0-tritolylporphyrin 55 5_ (ij-Hydroxyphenyl )-10,15, 20-tripheny lporphyrin 57 Preparation of 1,6- Mtosyloxyftes_ne 58 1, 6-Bte-para-formylphenoxyhexane 60 l-Hydroxy-6-para-formylphenoxyhexane 61 5_ [(lj_ (6-Hydroxy-l-hexoxy )phenyl] -10,15,20- tritoly lporphyrin 63 5,10,15-Tri-p-anisy1-20- [4- [6-[p-(10,15,20-tri-p- anisy1-5-porphinyl)phenoxy]hexoxy]phenyl]porphine.... 65 5,10,15-Tri-p-toly1-20- [4-[6- [p-(10,15,20-tri-p- toly1-5-porphinyl)phenoxy]hexoxy]phenyl]porphine 68 5,10,15-Triphenyl-20- [*•- [6-(10,15,20-tripheny 1-5- porphinyl )phenoxy] hexoxy] phenyl] porphine 72 (vi) PAGE PART CB) - TETRAPHENYLBACTERIOCHLORINS AND CHLORINS (MONOMERS AND DIMERS) 75 weso-Tetraphenylbacteriochlorin 75 meso-Tetrapheny Ichlorln 77 5_ [4-(6-Hydroxy-l-hexoxy)phenyl]-10,15,20- tritoly lbacteriochlorin 79 5_ [4_(6-Hydroxy-l-hexoxy)phenyl]-10,15,20- tritolylchlorin 81 5,10,15-Tri-p-tolyl-20- [M- [6- [p-(10,15,20-tri-p- toly1-5-bacteriochlorinyl)phenoxy]hexoxy]phenyl] bacteriochlorin 82 5,10,15-Tri-p-tolyl-20-[4-[6- [p-(10,15,20-tri-p- tolyl-5-chlorinyl)phenoxy]hexoxy]phenyl]chiorin 8 M PART (C) - ZINC METALLO-DERIVATIVES OF THE MESO- TETRAPHENYLPORPHYRINS, CHLORINS AND BACTERIOCHLORINS (MONOMERS AND DIMERS) 86 Zinc Tetraphenylporphin 86 Zinc Tetrapheny lporphin Dimer 88 Zinc Tetraphenylchlorin 89 Zinc Tetraphenylchlorin Dimer 91 Zinc Tetrapheny lbacteriochlorin 92 Zinc Tetrapheny lbacteriochlorin Dimer 9^ PART (D) - ATTEMPTED SYNTHESIS OF TETRA-MESO- [p,p'- (.3 , 3 ' -PHENOXYPROPOXYPHENYL)] -STRATI-BIS- PORPHYRIN 96 p- 3-Bromopropoxybenzaldehyde 96 (vii) PAGE 5,10,15,20-Tetra-[p-(3-bromopropoxy)phenyl]- porphyrin 98 5,10,15,20-Tetra-(4-propionylphenyl)porphyrin 101 5,10,15,20-Tetra-(4-hydroxyphenyl)porphyrin 103 5,10,15,20-Tetra-[(p1-formyl-3-phenoxy-p- propoxy)phenyl] porphyrin 105 Tetra-meso- [p,p'-(3,3'-phenoxypropoxyphenyl)- B tra ti-fcisporphyr in 106 REFERENCES 108 OPTICAL SPECTRAL APPENDIX 117 (viii) OPTICAL SPECTRAL APPENDIX PAGE TetraphenyIporphine (Monomer) 118 5_ (6-Hydroxy-l-hexoxy) phenyl]-10,15, 20- tritoly Iporphyrin 119 Tetrapheny Iporphine (Dimer) 120 Tetraphenylchlorin (Monomer) 121 Tetraphenylchlorin (Dimer) 122 Tetrapheny lbacteriochlorin (Monomer) 123 Tetrapheny lbacteriochlorin (Dimer ) 12^ Zinc Tetrapheny Iporphine (Monomer) 125 Zinc Tetrapheny Iporphine (Dimer) 126 Zinc Tetraphenylchlorin (Monomer) 127 Zinc Tetraphenylchlorin (Dimer) 128 Zinc Tetrapheny lbacteriochlorin (Monomer) 129 Zinc Tetraphenylbacteriochlorin (Dimer) 130 (ix) ABBREVIATIONS In this work the terms porphyrin, porphine and porphin are used interchangeably. Abbreviations which may occur without definition include: Abs. == Absorbance ATP == Adenosine Triphosphate DDQ == 2,3-Dichloro-5,6-dicyanobenzoquinone DKF == N,N-dimethylformamide EPE == Electron Paramagnetic Resonance Hz = Hertz (cycles per second) I = Intensity Lit. == Literature M.W. == Molecular Weight Ref. == Reference TFA == Trifluoroacetic acid TPBC == me so-Tetraphenylbacteriochlorin TPC == meso-Tetraphenylchlorin TPP == me so-TetraphenyIporphyrin (x) STRUCTURE AND NOMENCLATURE The nomenclature (a) is that recommended for tetra- pyrrolic macrocycles by IUPAC rules for nomenclature, J. Amer. Chem. Soc. 82, 5582 (I960). In this thesis the protons 2,3,7,8,12,13,17,18 are referred to as the 6-pyrrole protons. The carbons 1,4, 6,9,11,14,16,19 are the a-carbons. The positions 5,10, 15,20 are the meso-positions. -1- INTRODUCTION (a) Natural occurence and Importance of porphyrin dimers and aggregates. Porphyrin aggregates play an important role in both 1 2 photosynthetic and metabolic processes. ' The biosphere depends upon photosynthesis to carry out the conversion of photonic into chemical energy as well as to maintain an oxidizing atmosphere for catabol- ism (conversion of organic compounds to C02) which pro• vides the energy necessary to drive endergonic biochemical processes. The classical reaction of photosynthesis requiring chlorophyll-a (2) involves C02 fixation, namely C02 + H20 -> [CH20] + 02 (1) (light, chlorophyll) where [CH^O] is a carbohydratcarbohyd: e and water serves as the oxidizable hydrogen donor. H. C&R CCLCH? (2) (3) A reaction similar to (1) occurs in photosynthetic bacteria which utilize bacteriochlorophyll (3) and hydrogen -2- donors other than water. The photosynthetic process divides naturally into 3 ^ light-driven primary reactions ' and the subsequent CO^ reduction steps studied by Calvin, Bassham, and 5 coworkers. Under the title of primary reaction is in• cluded the conversion of light energy into reductants and oxidants and, in the case of green plants and blue-green algae, the chemical and physical states involved in the oxygen-evolving apparatus. The primary events of photosynthesis take place in a photosynthetic unit where a large number of chlorophyll (Chi) molecules act cooperatively as an antenna to ab• sorb visible light and to transfer the electronic excit• ation, so produced to a photoreaction centre or trap.^ In the excited trap, an electron is ejected from a special 7 pair of chlorophyll molecules, Chi , thereby creating sp a radical, Chl^, in which the unpaired electron is delocalized over the n-systems of both macrocycles. The Chi of photosystem I in green plants the sp {i.e. radical of P700) has a characteristic Gaussian electron spin resonance (ESR) signal with a free-electron g-value of 2.0025 and a signal width {i.e. twice the Gaussian • 8 standard deviation) of 7 gauss (1 gauss = 10 tesla) . Evidence for the participation of just two chlorophyll molecules in sharing