Pulse radiolysis and cyclic voltammetry studies of redox properties of phenothiazine radicals

One-electron transfer equilibria between seven phenothiazines were characterized by pulse radiolysis, producing radical-cations via oxidation by Br2·− or (SCN)2·− radicals. The reduction potentials of the phenothiazine radicals were determined by cyclic voltammetry. As an independent check, the redox equilibrium between one phenothiazine and the redox indicator ABTS was investigated. The data establish phenothiazines as useful indicators for radical redox properties. However, there are potential problems of aggregation, additional reactions with Br−/Br2·− and reactivity of the radicals towards buffers or other nucleophiles.