Background Emission of Electrogenerated Chemiluminescence during Oxidation of Tri-n-propylamine from the Dimeric 1Δg State of O2

The background electrogenerated chemiluminescence (ECL) emission observed only upon electrochemical oxidation of tri-n-propylamine (TPrAH) on a platinum electrode is a limiting factor in ECL analytical techniques and is poorly understood. We studied this reaction in aerated acetonitrile (MeCN) solution with TPrAH oxidized at a constant potential at the Pt surface and observed ECL spectra with an emission band at 630 nm, which is characteristic of the emission of the dimeric (1)Delta(g) state of O-2. No ECL emission was observed when the same solution was deaerated. This background ECL emission is attributed to the reaction between dissolved oxygen and two different products of TPrAH oxidation: the TPrAH(center dot) radical that reduces O-2 to the superoxide ion and the TPrAH(center dot+) radical cation that oxidizes this species to singlet O-2.