Light-driven water oxidation with a molecular tetra-cobalt(III) cubane cluster.

Photoinduced water oxidation to molecular oxygen takes place in systems made of [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) as the photosensitizer, [Co4O4(O2CMe)4(py)4] (py = pyridine) as the molecular catalyst and Na2S2O8 as the sacrificial electron acceptor. The photochemical quantum yield of the process reaches the outstanding value of 30% and depends on pH and catalyst concentration. Transient absorption spectroscopy experiments aimed to clarify the first events of the photocatalytic process are also reported.