Distance dependent rates of photoinduced charge separation and dark charge recombination in fixed distance porphyrin-quinone molecules
Three zinc tetraphenylporphyrin-anthraquinone derivatives were prepared in which the edge-to-edge distances between the porphyrin and quinone ..pi.. systems are fixed by a rigid hydrocarbon spacer molecule. Triptycene, trans-1,2-diphenylcyclopentane, and adamantane were used to fix the porphyrin-anthraquinone distance at 2.5, 3.7, and 4.9 A, respectively. These molecules possess 1,2, and 3 saturated carbon atoms, respectively, between the porphyrin donor and the quinone acceptor. Rate constants for photoinduced electron transfer from the lowest excited singlet state of the zinc tetraphenylporphyrin donor to the anthraquinone acceptor were measured. In addition, the corresponding radical ion pair recombination rate constants for each of these molecules were also determined. The rate constants for both photoinduced charge separation and subsequent radical ion pair recombination decrease by approximately a factor of 10 for each saturated carbon atom intervening between the porphyrin donor and the quinone acceptor. These results are consistent with a model in which the rate of electron transfer is determined by weak mixing of the sigma orbitals of the saturated hydrocarbon spacer with the ..pi.. orbitals of the donor and acceptor. 22 refs., 5 figs.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31-109-ENG-38
- OSTI ID:
- 5883348
- Report Number(s):
- CONF-860425-26; ON: DE86010511
- Resource Relation:
- Conference: 191. American Chemical Society national meeting, New York, NY, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoinduced electron transfer in fixed distance chlorophyll-quinone donor-acceptor molecules
Dependence of rate constants for photoinduced charge separation and dark charge recombination on the free energy of reaction restricted-distance porphyrin-quinone molecules
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTHRAQUINONES
ELECTRON TRANSFER
REACTION KINETICS
PORPHYRINS
ZINC COMPOUNDS
EXCITED STATES
RECOMBINATION
AROMATICS
CARBOXYLIC ACIDS
ENERGY LEVELS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
QUINONES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)