Photoelectrochemical investigations of phenosafranine dye bound to some macromolecules

Abstract

Macromolecular-bound phenosafranine dyes have been synthesized and characterized. The absorption spectra of the polymer-bound dyes show a bathochromic shift while the emission spectra shift slightly to higher frequency. Cyclic voltammetry of polymeric phenosafranines adsorbed at the carbon electrode show the subsequent two-electron redox reaction of the dye. Flash photolysis of the monomeric and polymeric dyes in the presence of EDTA produce the one-electron reduced dye which disproportionates; the disproportionation rate constant was measured to be 10⁹ and 10⁸ dm³ mol^-1 s^-1, respectively. Photoelectrochemical studies of the macromolecular phenosafranine indicate different behaviour depending upon the macromolecule. In the case of an electrode coated with a film of poly(acrylamidomethylphenosafranine-co-methylolacrylamide) cathodic behaviour was observed with reference to an inert electrode, while and electrode, coated with a film of poly(acrylamidomethylphenosafranine-co-methylolacrylamide-co-vinylpyridine) exhibited enodic polarity. A water-splitting regenerative cell was shown to operate using the polymeric phenosafranine-coated electrodes.