ABSTRACT

372The sources of the electrochemiluminescence (ECL) during the electrochemical synthesis of polyaniline (PAn) and copolymers of aniline (An) and luminol (Lum) by different composition at high electrode potentials have been investigated and analyzed. It was proposed that the generation of low intensity of luminosity in acidic aqueous solutions at the potentials over + (1.3–1.6) V (respectively to the silver/silver chloride saturated electrode) is related with irreversible destruction of the PAns in the form of pernigraniline as a result of their interaction with free radical intermediates of oxidation of solvent (water) and anions of the base electrolyte. It was found, that in a case of An and Lum copolymerization the optimal conditions for obtaining of copolymers with fluorescent properties is the using of aqueous–dimethylsulfoxide (DMSO) medium at volumetric ratio of the solvents 9:1. It was shown that obtained by varying the ratio of monomers in the initial polymerization mixture copolymers exhibit the electrochemiluminescent activity in aqueous alkaline solutions (pH = 10.5). The feature of ECL of copolymers is the presence of two waves of the appearance of luminosity, namely, in the intervals of the potentials + (0.4–1.0) V and + (1.0–2.5) V. It was suggested, that the source of the ECL is a direct electrochemical oxidation (the first wave) and chemical oxidation by free radicals of electrochemically generated intermediates (so-called, the second wave) of luminolic fragments of copolymeric chain.