Electrochemiluminescence Enhanced by a Non-Emissive Dual Redox Mediator.

A sulfonated tris(1-phenylpyrazolato)iridium(III) complex ([Ir(sppz)]) serves as a proof-of-concept non-emissive enhancer of the widely used ECL detection system of tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)]) with tri-n-propylamine (TPrA) co-reactant, acting through electrocatalysis of TPrA oxidation and efficient chemi-excitation of the luminophore. Using self-interference ECL spectroscopy, we show that the enhancer extends diffusion of the required electrogenerated precursors from the electrode surface. Previously reported enhancement through these pathways has been confounded by the inherent ECL of the enhancer, but the increase in [Ru(bpy)] ECL intensity using [Ir(sppz)] was obtained without its concomitant emission.

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)]) and tri--propylamine is enhanced by an order of magnitude by -[Ir(sppy)] (where sppy = 5'-sulfo-2-phenylpyridinato- ,), through a novel 'redox mediator' pathway. Moreover, the concomitant green emission of [Ir(sppy)]* enables internal standardisation of the co-reactant ECL of [Ru(bpy)]. 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.