Rate-Determining Step in the Electrogenerated Chemiluminescence from Tertiary Amines with Tris(2,2‘-bipyridyl)ruthenium(II)

Abstract

The rates and mechanism of coreactant electrogenerated chemiluminescence (ECL) from tris(2,2‘-bipyridyl)ruthenium(II) (Ru(bpy)32+) and the tertiary amines, tripropylamine (TPrA) and trimethylamine (TMeA), in aqueous solution were investigated. Transient (0.5 ms) potential steps were used with microelectrodes to investigate the emission time course under a variety of solution conditions. With amine concentrations that are low with respect to Ru(bpy)32+, the emission rises continually during the transient potential step and decays slowly after its termination. In contrast, the emission approaches a plateau during the potential step and is rapidly extinguished afterward with concentrations of Ru(bpy)32+ that are much lower than the amine concentration. At intermediate pH values, the emission intensity increases approximately linearly with pH. The emission after the potential step is unaffected by the rest potential. To simulate these temporal characteristics by finite difference methods, a mechanism employin...