Photoinduced Electron and Energy Transfer in Molecular Assemblies

北卡罗来纳大学(教堂山)Thomas Meyer的这一项目，在无机、生物无机和有机金属化学计划中，涉及到分子组装中光致电子和能量转移的研究，其中包括作为生色团的Ru(II)、Os(II)和Re(I)多吡啶配合物的扩展阵列以及将这些阵列连接到电子供体和受体的各种氧化还原载体。后一部分的势能将被选择来提供自由能梯度，从而使电子和空穴远离初始激发态的金属中心。瞬时红外光谱和拉曼共振光谱将被用来确定电荷分离激发态的氧化和还原位置。将合成用于研究将单光子、单电子事件转化为催化成键反应所需的多个氧化还原等价物的系统。它们将围绕一个金属氧中心构建，该中心对醇氧化为醛具有催化活性。植物在光合作用过程中完成的光能到化学能的转换，在很大程度上让科学家们摸不着头脑。在光合作用中，单个光子刺激多个氧化还原过程，导致化学键的形成和断裂。该项目利用无机光化学的最新进展，提出了构建大分子组件的方法，该组件将产生可用于刺激多个氧化还原事件的分离的电子-空穴对。这样的研究为最终利用太阳能进行化学加工奠定了有价值且亟需的基础工作。

This project of Thomas Meyer, University of North Carolina (Chapel Hill), in the Inorganic, Bioinorganic and Organometallic Chemistry Program, involves the study of photoinduced electron and energy transfer in molecular assemblies that include extended arrays of polypyridyl complexes of Ru(II), Os(II) and Re(I) as chromophores and various redox carriers coupling these arrays to electron donors and acceptors. The potentials of the latter moieties will be chosen to provide a free energy gradient so that electrons and holes migrate away from the initial excited state metal centers. The transient infrared and Raman resonance spectroscopies will be used to determine the sites of oxidation and reduction in the charge separated excited state. Systems will be synthesized for study of conversion of single-photon, single-electron events into multiple redox equivalents that are required for catalytic bond-forming reactions. These will be constructed around a metal oxo center that is catalytically active for the oxidation of alcohols to aldehydes. The conversion of light energy to chemical energy, as accomplished by plants during photosynthesis, has largely eluded scientists. In photosynthesis, a single photon stimulates multiple redox processes that lead to formation and cleavage of chemical bonds. This project draws upon recent advances in inorganic photochemistry to suggest ways that large molecular assemblies can be constructed that will generate a separated electron-hole pair that can be utilized to stimulate multiple redox events. Studies such as this lay valuable, and badly needed, ground work for ultimately utilizing solar energy for chemical processing.