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

The classic and most widely used co-reactant electrochemiluminescence (ECL) reaction of tris(2,2′-bipyridine)ruthenium(ii) ([Ru(bpy)(3)](2+)) and tri-n-propylamine is enhanced by an order of magnitude by fac-[Ir(sppy)(3)](3−) (where sppy = 5′-sulfo-2-phenylpyridinato-C(2),N), 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.