Visible light-driven water oxidation catalyzed by mononuclear ruthenium complexes

A series of mononuclear ruthenium water oxidation catalysts (WOCs) [Ru(bda)L2] (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid; L = N-cyclic aromatic ligands) were investigated in three-component light-driven water oxidation systems composed of photosensitizers, a sacrificial electron acceptor, and WOCs. A high turnover number of 579 for water oxidation was achieved in the homogeneous system using complex 4 ([Ru(bda)(4-Br-pyridine)2]) as the WOC, and a high quantum efficiency of 17% was found which is a new record for visible light-driven water oxidation in homogeneous systems.