Ciofini Ilaria, Lainé Philippe P, Bedioui Fethi, Adamo Carlo
Laboratoire d'Electrochimie et Chimie Analytique, CNRS UMR-7575, Ecole Nationale Supérieure de Chimie de Paris, 11 rue P. et M. Curie, F-75231, Paris Cedex 05, France.
J Am Chem Soc. 2004 Sep 1;126(34):10763-77. doi: 10.1021/ja0482278.
Ru(II) and Os(II) complexes (P) of [4'-(p-phenyl)]terpyridyl ligand (ptpy) derivatized with an electron acceptor (A) of the triphenylpyridinium (H3TP+) type have been recently proposed as functional models for electron-transfer (ET) processes in the context of artificial photosynthesis. These inorganic dyads, P-A, are expected to undergo intramolecular photoinduced ET to form a charge separated (CS) state of pivotal interest. To draw a complete picture of possible ET processes, the ground- and excited-state properties of these complexes, both in their native and monoreduced forms, have been studied by the means of density functional theory (DFT). A time-dependent-DFT approach (TDDFT) was used to interpret the electronic spectra, while additional spectroscopic measurements have been carried out in order to complete the available experimental information and to further confirm the theoretical issues. Besides the noticeable quantitative agreement between computed and experimental absorption spectra, our results allow us to clarify, by first principles, the actual nature and interplay of the electronic and geometrical coupling between the acceptor moiety and the photosensitizer. The possibility of a direct (optical) ET from the ground state to the targeted *[P+-A-] CS state is theoretically postulated and found to be consistent with available photophysical data (transient absorption spectroscopy). Concerning backward ET (from the CS state), the occurrence of a quinoidal-like electronic redistribution inherent to the photoreduced acceptor-ligand is proposed to favor efficient charge recombination.
最近，已提出用三苯基吡啶鎓（H3TP+）型电子受体（A）衍生化的[4'-(对苯基)]三联吡啶配体（ptpy）的钌（II）和锇（II）配合物（P）作为人工光合作用背景下电子转移（ET）过程的功能模型。这些无机二元体系P-A预计会发生分子内光致电子转移，形成具有关键意义的电荷分离（CS）态。为全面了解可能的电子转移过程，通过密度泛函理论（DFT）研究了这些配合物在其天然和单还原形式下的基态和激发态性质。采用含时密度泛函理论方法（TDDFT）解释电子光谱，同时进行了额外的光谱测量，以完善现有的实验信息并进一步证实理论问题。除了计算光谱与实验吸收光谱之间显著的定量一致性外，我们的结果还使我们能够从第一性原理出发，阐明受体部分与光敏剂之间电子和几何耦合的实际性质及相互作用。理论上推测了从基态到目标*[P+-A-] CS态的直接（光学）电子转移的可能性，并发现其与现有光物理数据（瞬态吸收光谱）一致。关于反向电子转移（从CS态），有人提出光还原受体-配体固有的类醌电子重分布的发生有利于有效的电荷复合。
