Artificial Photosynthetic Reaction Center with a Coumarin-Based Antenna System

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• 作者：Vikas Garg ; Gerdenis Kodis ; Paul A. Liddell ; Yuichi Terazono ; Thomas A. Moore ; Ana L. Moore ; Devens Gust
• 刊名：Journal of Physical Chemistry B
• 出版年：2013
• 出版时间：September 26, 2013
• 年：2013
• 卷：117
• 期：38
• 页码：11299-11308
• 全文大小：481K
• 年卷期：v.117,no.38(September 26, 2013)
• ISSN：1520-5207

文摘

In photosynthesis, sunlight is absorbed mainly by antenna chromophores that transfer singlet excitation energy to reaction centers for conversion to useful electrochemical energy. Antennas may likewise be useful in artificial photosynthetic systems that use sunlight to make fuels or electricity. Here, we report the synthesis and spectroscopic properties of a molecular hexad comprising two porphyrin moieties and four coumarin antenna chromophores, all organized by a central hexaphenylbenzene core. Light absorbed by any of the coumarins is transferred to a porphyrin on the 1鈥?0 ps time scale, depending on the site of initial excitation. The quantum yield of singlet energy transfer is 1.0. The energy transfer rate constants are consistent with transfer by the F枚rster dipole鈥揹ipole mechanism. A pyridyl-bearing fullerene moiety self-assembles to the form of the hexad containing zinc porphyrins to yield an antenna鈥搑eaction center complex. In the resulting heptad, energy transfer to the porphyrins is followed by photoinduced electron transfer to the fullerene with a time constant of 3 ps. The resulting P^鈥?鈥揅₆₀^{鈥⑩€?/sup> charge-separated state is formed with an overall quantum yield of 1.0 and decays with a time constant of 230 ps in 1,2-difluorobenzene as the solvent.}