Synthesis and electro- and photo-catalytic properties of a dinuclear cobalt(III) complex supported by 2-pyridylamino-N,N-bis(2-methylene-4,6-bimethyl)phenol

Abstract

The reaction of 2-pyridylamino-N,N-bis(2-methylene-4,6-bimethyl)phenol (H2L) with CoCl2·6H2O affords the dinuclear cobalt complex [L2Co2Cl2] (1), a new molecular catalyst for both electrolytic and photolytic water reduction. 1 can electrocatalyze hydrogen evolution from water with a turnover frequency (TOF) of 921.95mol of hydrogen per mole of catalyst per hour at an overpotential of 738mV (pH 7.0). Additionally, under photoirradiation with blue light (λmax=469nm), 1, together with [Ru(bpy)3]Cl2 and ascorbic acid in a pH 4.0 aqueous solution also produces hydrogen with a remarkable turnover number (TON) of 14460mol of H2 per mol of catalysts. This performance is significantly better than those of other molecular cobalt catalysts reported in the literature for photochemical hydrogen production.