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 soluti ons markedly. This effect arose from the preconcentration of FM on electrod e surfaces. A partition coefficient of about 2.3 x 10(4) was obtained for t he FM distribution between the polymer film and an acidic aqueous solution. Although adding 1-propanol to the solution lowered it, a sharp drop observ ed 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 ind icated that the partition coefficient of the oxidized form FM+ was about 40 0 times lower than that of the uncharged form. Since the surface concentrat ion of FM more than doubled upon reducing the polymer, no donor-acceptor in teraction may play a major role in determining a binding interaction betwee n FM and the polymer. The pH dependence of the surface concentration sugges ted that the protonated primary amino group of the polymer strengthens the chemical interaction. Since FM formed an insoluble 1: 1 complex with monome ric phenosafranin in acidic solutions, one can safely state that the polyme r interacts specifically with FM, thus reducing its activity coefficient in the polymer phase greatly. (C) 2001 Elsevier Science B.V. All rights reser ved.