| 研究実績の概要 |
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.
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