Introducing electrostatic interaction into Ru(bda) complexes for promoting water-oxidation catalysis

Ru(bda) (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid) complex is a kind of well-known water oxidation catalyst, which goes through the bimolecular I2M mechanism with an inter-catalyst O−O coupling step. Recently, we developed two facile strategies to accelerate O−O coupling via introducing the electrostatic interaction into Ru(bda)-catalysed systems. In this work, a series of Ru(bda) complexes with different charged groups on different positions were synthesized to demonstrate the general applicability of these design strategies. It found these catalytic systems with attractive electrostatic interaction display much better activity, and the position of the charged substituents also has a significant influence on the catalytic activity.