Long-Lived Radical Cations as Model Compounds for the Reactive One-Electron Oxidation Product of Vitamin E

Abstract

Heterocyclic compounds with structures similar to vitamin E, but without the hydroxyl hydrogen atom, were synthesized and their electrochemical behavior examined in acetonitrile solutions and as solids in aqueous solutions of varying pH by attaching the compounds to the surface of a glassy carbon electrode. Compound 1, containing a fully methylated aromatic ring was found to be the most long-lived following one-electron oxidation, with its radical cation (1 +.) surviving in acidic aqueous solutions and able to be isolated as a salt, 1+.(SbF6-), when reacted with NOSbF6 in CH3CN. Electrochemical, UV-vis and FTIR experiments on 1+., in addition to the results from theoretical calculations, indicated that the electrochemical, electronic and structural properties of 1+. are very similar to those of the radical cation of vitamin E.