Current enhancing effect of poly[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium]films on the electrode reaction of anthraquinonedisulfonate

The charge transfer rate for anthraquinonedisulfonate reduction at electrod es modified with poly[1 -methyl-3-(pyrrol-1-yl-methyl)pyridinium] chloride films was determined as a function of the electrode potential, solution pH, and solvent composition by electrochemical impedance spectroscopy. The pol ycationic film reduced the apparent heterogeneous rate constant of the redo x reaction by about two orders of magnitude relative to a naked electrode. This decrease resulted from strong binding of the reacting species to the p olymer and a repulsive interaction between the reacting species in the film . On the other hand, the polycationic film extracted a large amount of anth raquinonedisulfonate from an aqueous solution: the partition coefficient am ounted to as much as 7 x 10(4). Because of the resulting large increase in the voltammetric current of the redox reaction, the polymer-modified electr odes enabled us to determine traces of the redox species. (C) 1999 Elsevier Science S.A. All rights reserved.