A redox-mediator pathway for enhanced multi-colour electrochemiluminescence in aqueous solution

Abstract

The classic and most widely used co-reactant electrochemiluminescence (ECL) reaction of tris(2,2'-bipyridine)ruthenium(ii) ([Ru(bpy)₃]²⁺) and tri-<i>n</i>-propylamine is enhanced by an order of magnitude by <i>fac</i>-[Ir(sppy)₃]^3- (where sppy = 5'-sulfo-2-phenylpyridinato-<i>C</i> ²,<i>N</i>), through a novel 'redox mediator' pathway. Moreover, the concomitant green emission of [Ir(sppy)₃]^3-* enables internal standardisation of the co-reactant ECL of [Ru(bpy)₃]²⁺. This can be applied using a digital camera as the photodetector by exploiting the ratio of R and B values of the RGB colour data, providing superior sensitivity and precision for the development of low-cost, portable ECL-based analytical devices.