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备受关注，其利用一直是重要的研究课题之一。在过去的几十年里，人们研究了利用过渡金属络合物进行人工光合作用的化学方法。特别是具有芳香族二亚胺配体[Re(CO)3Lx]的三甲酰基Re(I)配合物由于其独特的光谱、光物理和光氧化还原性质而受到广泛的关注。到目前为止，我们设计合成了四个具有一个或两个芳基硼烷电荷转移单元(S)ReBphen/ReB2phen或ReBbpy/ReB2bpy的三羰基Re(I)配合物，并对其光谱/光物理性质进行了详细的研究。计算结果与预测结构吻合较好，其中Re(I)中心呈近八面体配位构型，羰基配体呈面状排列。此外，在CO2气氛下，用DMF/TEOA溶液中的光催化活性研究了它们对CO2还原的光催化活性。所有的络合物都被证明是CO2光还原的活性催化剂，尽管其效率取决于络合物的性质。然而，与不含芳基硼烷单元的参比络合物相比，芳基硼烷络合物对二氧化碳形成的周转数(吨)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.