ELECTROCHEMICAL-BEHAVIOR OF LB FILMS CONTAINING A MIXTURE OF VIOLOGENAND A PHOSPHOLIPID

The electrochemical behavior of mixed monolayers of N-tetradecyl-N'-me thyl viologen (TMV) and L-alpha-dimyristoylphosphatidic acid (DMPA) ha s been studied. Mixed monolayers of TMV/DMPA = 1:2 have been obtained at the air-water interface and transferred by the Langmuir-Blodgett (L B) method at pi = 40 mN m(-1) onto In and Sn oxide (ITO) electrodes. T hese LB films were used as the working electrode in a conventional ele ctrochemical cell and immersed in aqueous solutions with different ele ctrolytes. The influence of the type and the electrolyte concentration on the voltammetric peaks related to the two one-electron processes o f TMV has been studied. The formation of an insoluble salt of viologen perchlorate on the surface of the electrode is observed when concentr ations of perchlorate higher than 0.3 M are used. Due to this, a reori entation of the polar group of the viologen in the transferred mixed m onolayer from a flat to a perpendicular position is postulated.