アリールホウ素置換基を有する遷移金属錯体を利用した新規人工光合成系の創製

近年来，化石燃料带来的能源短缺和环境污染已成为世界上亟待解决的两大问题。因此，太阳能作为一种可持续能源已成为人们关注的焦点，其利用已成为重要的研究课题之一。利用过渡金属配合物进行人工光合作用的化学途径在过去的几十年里得到了广泛的研究。特别是一种具有芳香二亚胺配体的三羰基铼(I)配合物[Re(CO)3LX]，由于其独特的光谱、光物理和光氧化还原性质而受到广泛关注。目前，设计/合成了四种具有一个或两个芳基硼烷电荷转移单元的新型三羰基铼配合物ReBphen/ReB2phen或ReBbpy/ ReB2bpy，并对其光谱/光物理性质进行了详细的研究。然后，对ReB2phen进行x射线晶体学分析。结果与预测结果非常吻合，铼(I)中心呈近八面体配位，羰基配体呈面向排列。此外，通过DMF/TEOA溶液在CO2气氛下的光催化活性研究了它们对CO2还原的光催化活性。所有的配合物都被证明是CO2光还原的活性催化剂，尽管其效率取决于配合物的性质。然而，与不含芳基硼烷的参考配合物相比，芳基硼烷配合物的CO2生成周转率（TON）较低。

Recently, energy shortage from fossil fuels and pollution of the environments have been two largest issues to be solved in the world. Therefore, solar energy has been focused as a sustainable energy source and its utilization has been one of the important research topics. Chemical approaches toward artificial photosynthesis utilizing transition metal complexes have been studied in the past decades. In particular, a tricarbonyl rhenium(I) complex having an aromatic diimine ligand, [Re(CO)3LX], has been received extensive attention due to the unique spectroscopic, photophysical, and photoredox properties.Until now, four novel tricarbonyl rhenium(I) complexes having one or two arylborane charge transfer unit(s) ReBphen/ReB2phen or ReBbpy/ ReB2bpy were　designed/synthesized and the spectroscopic/photophysical properties were studied in detail.Then, X-ray crystallographic analysis of ReB2phen was conduceted. The results agree very well with the predicted structure of it, where the rhenium(I) center adopts a nearly octahedral coordination geometry and the carbonyl ligands are arranged in a facial orientation.Furthermore, the photocatalytic activities of them towards CO2 reduction were studied by photoirradiation of the complexes in DMF/TEOA solutions under CO2 gas atmosphere. All of the complexes were shown to be the active catalysts for CO2 photoreduction, although its efficiency was dependent on the nature of the complex. However, the arylborane complexes showed lower turnover numbers (TON) for CO2 formation compared to the reference complexes without arylborane units.