Analysis of active chemical species generated by electrolysis using non-aqueous capillary electrophoresis: Detection of the anion radical and the divalent anion of tetracyanoquinodimethane

We have investigated detection of the anion radical and the divalent anion of tetracyanoquinodimethane (TCNQ) by acetonitrile–CE under anaerobic conditions. With electrolysis at a potential of 0.0 V (vs. Ag/AgCl), an acetonitrile solution of TCNQ turned green, characteristic of the TCNQ anion radical (TCNQ−). Only one peak of the anionic compound was observed in CE of the electrolysis solution and it should be that of TCNQ−. Then, the electrolysis potential was shifted to −0.8 V expected to be sufficient potential for the further reduction of TCNQ−, and the solution turned almost colourless. In CE analysis of the latter solution, another anionic component possessing a larger electrophoretic mobility than that of TCNQ− was detected, and it was decomposed immediately under aerobic conditions. This product was strongly suggested to be the divalent anion of TCNQ, and the present method would contribute notably to detection of the unstable species.