Photoinduced Electron and Energy Transfer in Molecular Assemblies

北卡罗来纳大学教堂山分校的Thomas Meyer在无机、生物无机和有机金属化学项目中研究了分子组装中的光诱导电子和能量转移，包括Ru（II）、Os（II）和Re(I)作为发色团的多吡基络合物的扩展阵列和将这些阵列与电子供体和受体耦合的各种氧化还原载体。后一部分的势将被选择来提供一个自由能梯度，使电子和空穴从初始激发态金属中心迁移。瞬态红外和拉曼共振光谱将用于确定在电荷分离激发态中氧化和还原的位置。系统将被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。这些将围绕一个金属氧中心构建，该氧中心对醇氧化成醛具有催化活性。植物在光合作用过程中所完成的光能到化学能的转换，在很大程度上一直是科学家们的难题。在光合作用中，单个光子刺激多种氧化还原过程，导致化学键的形成和断裂。该项目借鉴了无机光化学的最新进展，提出了构建大分子组件的方法，这些大分子组件将产生一个分离的电子-空穴对，可以用来刺激多种氧化还原事件。诸如此类的研究为最终利用太阳能进行化学处理奠定了有价值且急需的基础工作。

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.