An octanuclear Cu(ii) cluster with a bio-inspired Cu4O4 cubic fragment for efficient photocatalytic water oxidation.

An octanuclear Cu(ii) cluster [Cu8(dpk·OH)8(OAc)4](ClO4)4 (dpk·OH = the monoanion of the hydrated, gem-diol form of di-2-pyridyl ketone) that contains two Cu4O4 cubic fragments similar to the Mn4CaO5 cluster in photosystem II (PSII) was found to be an efficient catalyst for photocatalytic water oxidation. In the [Ru(bpy)3]2+/Na2S2O8 system, it afforded an optimal oxygen yield, turnover number (TON) and turnover frequency (TOF) of 35.6%, 178 and 3.6 s-1, respectively, which are the highest values amongst all of the Cu-based photocatalytic water oxidation catalysts (WOCs).