Photoelectrochemical electron spin resonance. Part 2.—The reduction of crystal violet in acetonitrile

Abstract

The reduction of the dye crystal violet in acetonitrile solution at platinum electrodes has been investigated using in situ electrochemical e.s.r. and a channel electrode flow cell. In the dark, in the rigorous absence of oxygen, a one-electron reversible reduction takes place, producing the stable crystal violet radical, the e.s.r. spectrum of which was recorded. The behaviour in the presence of oxygen is also discussed. On irradiation with light of wavelength ca. 400 nm the radical is thought to undergo a chemical reaction with the solvent, and the electrode reduction process has the characteristics of an EC mechanism. The nature of this reaction is deduced from the e.s.r. signal strength/current/electrolyte flow rate data together with pure electrochemical measurements, and kinetic parameters are reported.