A Water-Soluble Copper-Polypyridine Complex as a Homogeneous Catalyst for both Photo-Induced and Electrocatalytic O2 Evolution

The water-soluble polypyridine copper complex [Cu(F(3)TPA)(ClO4)(2)] [1; F(3)TPA=tris(2-fluoro-6-pyridylmethyl)amine] catalyzes water oxidation in a pH 8.5 borate buffer at a relatively low overpotential of 610 mV. Assisted by photosensitizer and an electron acceptor, 1 also exhibits activity as a homogeneous catalyst for photo-induced O-2 evolution with a maximum turnover frequency (TOF) of (1.58 +/- 0.03) x 10(-1) s(-1) and a maximum turnover number (TON) of 11.61 +/- 0.23. In comparison, the reference [Cu(T-PA)(ClO4)(2)] [TPA=tris(2-pyridylmethyl)amine] displayed almost no activity under either set of conditions, implying the crucial role of the ligand in determining the behavior of the catalyst. Experimental evidence indicate the molecular catalytic nature of 1, leading to a potentially practical strategy to apply the copper complex in a photoelectrochemical device for water oxidation.