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Titolo:
The role of the electronic structure of the porphyrin as viewed by EPR/ENDOR methods in the efficiency of biomimetic model compounds for photosynthesis
Autore:
Huber, M;
Indirizzi:
Leiden Univ, Dept Mol Phys, NL-2300 RA Leiden, Netherlands Leiden Univ Leiden Netherlands NL-2300 RA NL-2300 RA Leiden, Netherlands
Titolo Testata:
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
fascicolo: 23, , anno: 2001,
pagine: 4379 - 4389
SICI:
1434-193X(200112):23<4379:TROTES>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
COVALENTLY-LINKED PORPHYRIN; RHODOBACTER-SPHAEROIDES; QUINONE TRIADS; EPR SPECTROSCOPY; CATION RADICALS; ANION-RADICALS; FREE-BASE; SYSTEMS; SOLVENT; ENDOR;
Keywords:
biomimetic model compounds; photosynthesis; electron transfer; electron spin resonance; porphyrins; quinones;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Huber, M Leiden Univ, Dept Mol Phys, POB 9504, NL-2300 RA Leiden, Netherlands Leiden Univ POB 9504 Leiden Netherlands NL-2300 RA , Netherlands
Citazione:
M. Huber, "The role of the electronic structure of the porphyrin as viewed by EPR/ENDOR methods in the efficiency of biomimetic model compounds for photosynthesis", EUR J ORG C, (23), 2001, pp. 4379-4389

Abstract

A project to investigate the parameters that determine the efficiency of biomimetic porphyrin quinone model compounds for photosynthesis is described. It should aid in understanding the origin of the high efficiency of energy conversion in the light-induced charge separation in photosynthesis. Specifically, the contribution of the electronic matrix element to the electrontransfer (ET) rates is addressed. Targeting the electronic structure of the ET components, EPR (electron paramagnetic resonance) and ENDOR (electron nuclear double resonance) spectroscopy were performed on the appropriate radical derivatives of the porphyrins and quinones to determine MO coefficients. Together with semiempirical MO methods, these coefficients were used toobtain information on the frontier orbitals of the donor and acceptor moieties, the porphyrins, and quinones of the model compounds. The porphyrin frontier orbitals (HOMO and LUMO) have been implicated in the balance of ET rates for charge separation and charge recombination, which is related to the efficiency. A model is presented to correlate the substitution pattern ofthe porphyrin with the efficiency of the model compound. In particular, the effect of porphyrin substitution, including the covalent link to an acceptor, arid the comparison of porphyrins with chlorins and chlorophylls are addressed. The model allows for a quantification of these effects in some cases. Differences in the frontier orbital structure suggest that the [5,10,15,20 tetraaryl(alkyl)porphyrinato]metal complexes are sufficiently different from chlorophylls to be nonideal model compounds. These results are related to recent publications, and possible improvements of experimental and theory approaches are addressed.

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Documento generato il 11/07/20 alle ore 14:30:17