Energy and photoinduced electron transfer in a wheel-shaped artificial photosynthetic antenna-reaction center complex |
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Authors: | Kodis Gerdenis Terazono Yuichi Liddell Paul A Andréasson Joakim Garg Vikas Hambourger Michael Moore Thomas A Moore Ana L Gust Devens |
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Institution: | Department of Chemistry and Biochemistry, Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe, AZ 85287-1604, USA. |
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Abstract: | Functional mimics of a photosynthetic antenna-reaction center complex comprising five bis(phenylethynyl)anthracene antenna moieties and a porphyrin-fullerene dyad organized by a central hexaphenylbenzene core have been prepared and studied spectroscopically. The molecules successfully integrate singlet-singlet energy transfer and photoinduced electron transfer. Energy transfer from the five antennas to the porphyrin occurs on the picosecond time scale with a quantum yield of 1.0. Comparisons with model compounds and theory suggest that the F?rster mechanism plays a major role in the extremely rapid energy transfer, which occurs at rates comparable to those seen in some photosynthetic antenna systems. A through-bond, electron exchange mechanism also contributes. The porphyrin first excited singlet state donates an electron to the attached fullerene to yield a P(*+)-C(60)(*-) charge-separated state, which has a lifetime of several nanoseconds. The quantum yield of charge separation based on light absorbed by the antenna chromophores is 80% for the free base molecule and 96% for the zinc analogue. |
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