New trinuclear dendritic complexes with [Ru(tpy)(bpy)X] n + (X=Cl, H 2 O; n=1, 2) for enhanced water oxidation and light-driven alcohol oxidation

A symmetric trinuclear ruthenium complex with [Ru(tpy)(bpy)(Cl)]+ (tpy=2,2′:6′,2″-terpyridine; bpy=2,2′-bipyridine) connected by 2,4,5-trimethylbenzene was easily prepared. The complex showed effective chemical water oxidation and light-driven oxidation activity of alcohols to corresponding aldehydes in water. When Cl− is replaced by H2O, the resulting complex exhibited over a twofold increase in O2 evolution activity compared with its parent complex. Moreover, compared with equimolar ruthenium amounts of the mononuclear complex with the H2O ligand, the trinuclear ruthenium complex with the conjugated ligand motif also displayed a two time increase in water oxidation activity.