Highly active and tunable catalysts for O-2 evolution from water based on mononuclear ruthenium(II) monoaquo complexes

The catalytic activity of [Ru(tpy)(bpy)OH2](2+) (tpy = 2,2': 6', 2 ''-terpyridine and bpy = 2,2'-bipyridine) increased by a 4'-substituted ethoxy group on the tpy ligand by more than one order of magnitude to give 1.1 x 10(-1) s(-1) of catalyst turnover frequency, which is comparable with the hitherto-reported champion data.