Photoinduced electron transfer in fixed distance chlorophyll-quinone donor-acceptor molecules
A series of fixed distance chlorophyll-quinone donor-acceptor molecules have been prepared. The donor consists of either methyl pyropheophorbide a or methyl pyrochlorophyllide a, while the acceptor is either benzoquinone or naphthoquinone. The acceptors are fused to a triptycene spacer group, which in turn is attached to the donors at their vinyl groups. Picosecond transient absorption measurements have been used to identify electron transfer from the lowest excited singlet state of the donor to the acceptor as the mechanism of fluorescence quenching in these molecules. The charge separation rate constants increase from 2 x 10/sup 10/ s/sup -1/ to 4 x 10/sup 11/ s/sup -1/ as the free energy of charge separation increases, while the radical pair recombination rate constants decrease from 1.2 x 10/sup 11/ s/sup -1/ to 2 x 10/sup 9/ s/sup -1/ as the free energy of recombination increases. The resulting total reorganization energy lambda = 0.9 eV.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6429804
- Report Number(s):
- CONF-870497-2; ON: DE87011412
- Country of Publication:
- United States
- Language:
- English
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Distance dependent rates of photoinduced charge separation and dark charge recombination in fixed distance porphyrin-quinone molecules
Related Subjects
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
ABSORPTION SPECTRA
AROMATICS
BINDING ENERGY
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHLOROPHYLL
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
ENERGY LEVELS
EXCITED STATES
FERMIONS
FLUORESCENCE
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ION PAIRS
LEPTONS
LUMINESCENCE
MOLECULES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
QUINONES
RADICALS
RECOMBINATION
SPECTRA
SYNTHESIS
VALENCE