Spectroelectrochemical identification of the active sites for protons and anions insertions into poly-(Azure a) thin polymer films

Poly-(Azure A) films deposited on indium-tin oxide electrodes were simultaneously characterized by visible/near-infrared spectroscopy and EIS techniques at different polarization potentials and pH. The instantaneous variation of the absorbance with the potential (dA/dE) at 685 and 875 nm was correlated with the kinetic parameters obtained from the analysis of the electrochemical impedance results (d Gamma(H)+(E)/dE and G(A)-). Thus, the relative participation of the hydrogen ion and anions was quantified in each chemical step coupled to the successive electron-transfer reactions of two different electroactive double bonds of this electrochromic material: an amino bridge and the phenothiazine ring. The stoichiometry of the active sites and counter ions into the host polymer are determined from the calculated kinetic ion-insertion parameters. This procedure allows the electrical and electrochemical properties of redox-conducting polymers to be known thoroughly.