Coordinated photoinduced electron and proton transfer in a molecular triad

Journal Article · Wed Feb 08 00:00:00 EST 1995 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00110a030· OSTI ID:6455555

Hung, S C; Macpherson, A N; Lin, S; Liddell, P A; Seely, G R; Moore, A L; Moore, T A; Gust, D ^[1]

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1. Arizona State Univ., Tempe, AZ (United States)

Excitation of carotenoid-porphyrin-quinone (C-P-Q) triads yields the porphyrin first excited singlet state, which decays by electron transfer to give a C-P[sup [center dot]+]-Q[sup [center dot]-] charge-separated state. Competing with rapid charge recombination is electron transfer from the carotenoid to produce a long-lived C[sup [center dot]+]-P-Q[sup [center dot]-] species. High quantum yields of the final state require tuning of electronic and thermodynamic factors to favor forward electron transfer over charge recombination. Triad 1 illustrates a new strategy for slowing charge recombination based on coupling photoinduced electron transfer to a change in proton chemical potential. The quantum yields and lifetimes of the final charge-separated states in the triads were assessed by monitoring the transient carotenoid radical cation absorptions. The results demonstrate that the yield of charge separation in multicomponent molecular photovoltaics can be increased by a coordinated electron and proton transfer process. It is also interesting that in 1 a substantial fraction of the intramolecular redox potential produced by photoinduced electron transfer is transformed into proton chemical potential. Elaboration of this concept could lead to photoinduced generation of proton motive force in a heterogeneous system. 24 refs., 3 figs.

• DOE Contract Number: FG03-93ER14404
• OSTI ID: 6455555
• Journal Information: Journal of the American Chemical Society; (United States), Vol. 117:5; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CAROTENOIDS
ELECTRON TRANSFER
PROTON TRANSPORT
MOLECULES
PHOTOCHEMICAL REACTIONS
PORPHYRINS
QUINONES
EMISSION SPECTRA
PHOTOVOLTAIC EFFECT
AROMATICS
CARBOXYLIC ACIDS
CHARGED-PARTICLE TRANSPORT
CHEMICAL REACTIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PIGMENTS
RADIATION TRANSPORT
SPECTRA
TERPENES
400201* - Chemical & Physicochemical Properties
400500 - Photochemistry
400102 - Chemical & Spectral Procedures