Modeling long-range photosynthetic electron transfer in rigidly bridged porphyrin-quinone systems

Journal Article · Thu Mar 07 04:00:00 EST 1991 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100158a010· OSTI ID:5748573

Antolovich, M; Keyte, P J; Oliver, A M; Paddon-Row, M N ^[1]; Kroon, J; Verhoeven, J W ^[2]; Jonker, S A; Warman, J M ^[3]

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1. Univ. of New South Wales, Kensington (Australia)
2. Univ. of Amsterdam (Netherlands)
3. Interuniversity Reactor Institute, Delft (Netherlands)

Photoinduced charge separation as well as subsequent charge recombination is studied in bichromophoric molecules containing a quinone unit (Q) and either a porphyrin (P) or a zinc porphyrin (ZnP) unit that are interconnected by a rigid saturated hydrocarbon bridge that unequivocally determines both the separation and the relative orientation of the chromophores. Across a bridge comprising a separation equivalent to two saturated carbon-carbon bonds (i.e., in P(2)Q), extensive direct overlap between the {pi}-systems of the chromophores is still possible and accordingly very fast photoinduced charge separation (typically on a 30-40-ps time scale) is observed. However, even across a bridge comprising an extended array of six saturated bonds, charge separation times in the order of 100 ps can still be realized if the driving force for this process is optimized by modification of the porphyrin and of the solvent (a minimum charge-separation time of 65 ps was observed for ZnP(6)Q in chloroform). This implies a rate of charge separation comparable to or somewhat higher than that of the charge transfer from pheophytin to quinone in natural photosynthesis in spite of the fact that the interchromophore distance in the latter process is slightly smaller. The time-resolved microwave conductivity method was employed to confirm the occurrence of photoinduced charge separation as well as to measure the rate of charge recombination in ZnP(6)Q.

• OSTI ID: 5748573
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 95:5; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
ABSORPTION SPECTRA
AROMATICS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
COMPLEXES
DATA
DATA ANALYSIS
ELECTRON TRANSFER
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
MEASURING METHODS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PORPHYRINS
QUINONES
SPECTRA
SYNTHESIS
ZINC COMPLEXES