Incorporation of 1,1′-ferrocenedimethanol into polyphenosafranin and a binding interaction between them

This paper describes the electrocatalytic effect of polyphenosafranin films on the oxidation of 1,1′-ferrocenedimethanol (FM). Electrode modification with the polymer raised the voltammetric current of FM in its dilute solutions markedly. This effect arose from the preconcentration of FM on electrode surfaces. A partition coefficient of about 2.3×104 was obtained for the FM distribution between the polymer film and an acidic aqueous solution. Although adding 1-propanol to the solution lowered it, a sharp drop observed at low 1-propanol concentrations cannot be ascribed to the medium effect on FM. A positive shift in the FM redox potential due to incorporation indicated that the partition coefficient of the oxidized form FM+ was about 400 times lower than that of the uncharged form. Since the surface concentration of FM more than doubled upon reducing the polymer, no donor–acceptor interaction may play a major role in determining a binding interaction between FM and the polymer. The pH dependence of the surface concentration suggested that the protonated primary amino group of the polymer strengthens the chemical interaction. Since FM formed an insoluble 1:1 complex with monomeric phenosafranin in acidic solutions, one can safely state that the polymer interacts specifically with FM, thus reducing its activity coefficient in the polymer phase greatly.