Electrochromic properties of conductive polyporphyrin films based on 5,10,15,20-tetrakis(4-aminophenyl)porphyrin and 5,10,15,20-tetrakis(4-pyridyl)porphyrin

Abstract

Polyporphyrin films based on 5,10,15,20-tetrakis(4-pyridyl)porphyrin and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin were obtained by electrochemical polymerization during the electrooxidation of the respective monomers. The polyporphyrin formation involved the side substituents, with the [Formula: see text]-conjugated porphyrin platform being preserved. The obtained polyporphyrins form uniform electroconductive coatings, tightly adhered to the electrode surface. The electrochromic properties were studied by the spectroelectrochemical method. Electronic absorption spectra of the films were recorded under the action of electric current at the stepwise potential changes within several intervals. The obtained polyporphyrin films were shown to possess electrochromic properties. The films were oxidized when exposed to anodic potentials and reduced when exposed to cathodic potentials. The electronic absorption spectra were used to calculate the optical band gap of the initial, oxidized and reduced films and to evaluate their conductivity. The highest conductivity was found in the electrochemically oxidized poly-5,10,15,20-tetrakis(4-aminophenyl)porphyrin film.