Electrogenera Ted Chemiluminescence Part Xxvii. E.c.l. and Electrochemical Studies of Selected Laser Dyes

The electrogenerated chemiluminescence (e.c.!.) and electrochemistry of the laser dyes, coumarin-2, coumarin-3D, rhodamine-GG (perchlorate), rhodamine-B (perchlorate), oxazine1 (perchlorate), and Nile Blue (perchlorate) were studied in acetonitrile using 0.1 M tetran-butylammonium perchlorate (TBAP) as a supporting electrolyte. Rather low intensity e.c.!. was obtained for all dyes except Nile Blue. A study of the electrochemical oxidation and reduction of coumarin-3D, oxazine-1 and rhodamine-GG using cyclic voltammetry and controlled potential coulometry demonstrated that chemical side reactions of the electrogenerated reactants are responsible for the low e.c.!. efficiency. In several cases the oneelectron transfer reaction at the electrode is followed by a dimerization reaction. The neutral free radical formed on reduction of oxazine-1 was investigated by electron spin resonance spectroscopy and coupling constants for it are reported. Some experiments in which the e.c.!. of mixtures of the dyes with rubrene or 9,10-diphenylanthracene were determined are also described.