Synthesis of a Novel Re(I)-Ru(II)-Re(I) Trinuclear Complex as an Effective Photocatalyst for CO2 Reduction
Akinari Umemoto, Yasuomi Yamazaki, Daiki Saito, Yusuke Tamaki, Osamu Ishitani
Bulletin of the Chemical Society of Japan
Supramolecular photocatalysts, which consist of redox photosensitizer and catalyst units, have recently attracted attention in the field of artificial photosynthesis. Aiming to construct a durable supramolecular photocatalyst for CO2 reduction, a new Re–Ru–Re trinuclear complex was successfully developed, where one Ru unit, acting as photosensitizer, was linked to two Re units, acting as catalysts, through ethylene chains. The novel complex was synthesized by creating two chelate moieties on the ligand of a Ru complex using the Negishi-coupling reaction, which were then coordinated to Re complexes. This trinuclear complex selectively photocatalyzed the reduction of CO2 to CO under visible light irradiation, with high durability compared with the corresponding Ru–Re binuclear complex and a mixed system of model mononuclear complexes. Absorption spectra and mass spectroscopic data of the reaction solutions revealed a rapid consumption of the electrons on the one-electron reduced species of the Ru unit, which led to suppression of the Ru unit decomposition, thereby maintaining its photosensitizing ability and product selectivity.
Absorption, Coordination chemistry, Fluorescence, Quantum yield, Quenching, Kinetics, Quantitation, Sensors, Materials, Inorganic chemistry