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

The reaction of 2-pyridylamino-N,N-bis(2-methylene-4,6-bimethyl)phenol (H2L) with CoCl2 center dot 6H(2)O 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 921.95 mol of hydrogen per mole of catalyst per hour at an overpotential of 738 mV (pH 7.0). Additionally, under photoirradiation with blue light (lambda(max) = 469 nm), I, together with [Ru(bpy)(3)]Cl-2 and ascorbic acid in a pH 4.0 aqueous solution also produces hydrogen with a remarkable turnover number (TON) of 14 460 mol of H-2 per mol of catalysts. This performance is significantly better than those of other molecular cobalt catalysts reported in the literature for photochemical hydrogen production. (C) 2016 Elsevier Ltd. All rights reserved.