Electrogenerated chemiluminescence of violanthrone in dimethyl sulfoxide

Violanthrone is an anthraquinone vat dye, which is resistant to photochemical damage. Most previous work has concentrated on its chemiluminescence properties. In this report, electrogenerated chemiluminescence (ECL) of violanthrone has been investigated in dimethyl sulfoxide with 0.1M of tetraethylammonium bromide as electrolyte. Violanthrone luminesces in the potential range between 0.0V and -4.0V. At the sweep rate 1000 mV/s, the intensity of the violanthrone ECL is about 2% of that of tris(2,2'-bipyridine) ruthenium(II) ion under the same conditions. It was found that bromine was also produced during the experiment, leading to the conclusion that the luminescence arises from the reaction between radical anion of violanthrone and molecular bromine. The mechanism is discussed in detail.