Electrochemiluminescent behavior of tris(2,2-bipyridine) ruthenium(II)/triethylamine in ionic liquid solution

The electrochemiluminescence (ECL) behaviors of tris(2,2-bipyridine)ruthenium(II)/triethylamine (Ru(bpy)3(2+)/TEA) in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) ionic liquid were investigated and compared with those in aqueous solution (pH 7.0 PBS) at a gold electrode. It was found that the Ru(bpy)3(2+)/TEA system gave rise to one small and one large peak ECL peak at anodic process. The small anodic ECL peak observed around +0.90 V is due to the direct electrochemical oxidation of TEA at the gold electrode and further chemiluminescent reaction of its oxidative product with Ru(bpy)(3)(2+). The large anodic ECL peak found around +1.35 V results from the reversible electrochemical oxidation of Ru(bpy)(3)(2+) coupled with a slow following reaction of TEA with Ru(bpy)(3)(3+). The effects of viscosity and ionic strength of ionic liquid on diffusion coefficients, catalytic efficiency, and ECL intensity were investigated and discussed to reveal the ECL mechanism of Ru(bpy)(3)(2+)/TEA system in the ionic liquid of BMIPF6.