Photoinduced charge separation and charge recombination to a triplet state in a carotene-porphyrin-fullerene triad
- Arizona State Univ. Tempe, AZ (United States)
A molecular triad consisting of a diarylporphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene (C{sub 60}) has been prepared and studied using time-resolved spectroscopic methods. In 2-methyltetrahydrofuran solution, the triad undergoes photoinduced electron transfer to yield C-P{sup .+}-C{sub 60}{sup .-}, which evolves into C{sup .+}-P-C{sub 60}{sup .-} with an overall quantum yield of 0.14. This state decays by charge recombination to yield the carotenoid triplet state with a time constant of 170 ns. Even in a glass at 77 K, C{sup .+}-P-C{sub 60}{sup .-} is formed with a quantum yield of nearly 0.10 and again decays mainly by charge recombination to give {sup 3}C-P-C{sub 60}. The fullerene triplet, formed through normal intersystem crossing, is also observed at 77K. the generation in the triad of a long-lived charge separated state by photoinduced electron transfer, the low-temperature electron transfer behavior, and the formation of a triplet state by charge recombination are phenomena previously observed mostly in photosynthetic reaction centers. 36 refs., 5 figs.
- OSTI ID:
- 466321
- Journal Information:
- Journal of the American Chemical Society, Vol. 119, Issue 6; Other Information: PBD: 12 Feb 1997
- Country of Publication:
- United States
- Language:
- English
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