Control of Excitation and Quenching in Multi-colour Electrogenerated Chemiluminescence Systems through Choice of Co-reactant

We demonstrate a new approach to manipulate the selective emission in mixed electrogenerated chemiluminescence (ECL) systems, where subtle changes in co‐reactant properties are exploited to control the relative electron‐transfer processes of excitation and quenching. Two closely related tertiary‐amine co‐reactants, tri‐n‐propylamine and N,N‐diisopropylethylamine, generate remarkably different emission profiles: one provides distinct green and red ECL from [Ir(ppy)3] (ppy=2‐phenylpyridinato‐C2,N) and a [Ru(bpy)3]2+ (bpy=2,2′‐bipyridine) derivative at different applied potentials, whereas the other generates both emissions simultaneously across a wide potential range. These phenomena can be rationalized through the relative exergonicities of electron‐transfer quenching of the excited states, in conjunction with the change in concentration of the quenchers over the applied potential range. Co‐reactant controlled emission: The selective excitation and quenching of electrogenerated chemiluminescence (ECL) luminophores with distinct electrochemical and photophysical properties is highly dependent on the nature of the co‐reactant, offering exquisite control of multiplexed ECL systems (see figure; TPA=tripropylamine, DIPEA=N,N‐diisopropylethylamine).