Electrochemical properties and Fourier transform-infrared spectroscopic investigations of the redox behaviour of poly(indole-5-carboxylic acid) in LiClO4-acetonitrile solutions.

D Billaud, B Humbert, L Thevenot, P Thomas, H Talbi

Index: Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 59(1) , 163-8, (2003)

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Abstract

Electropolymerisation of indole-5-carboxylic-acid leads to the formation of electroactive polymer films. Potentiostatic deposition of the related polymer, poly(indole-5-carboxylic-acid), was carried out at a constant potential at 1.35 V versus SCE. The cyclic voltammogram of the resulting polymer in LiClO4 (0.15 mol dm(-3))/acetonitrile solution is characterized by two poorly resolved anodic and cathodic set peaks. FTIR spectroscopy was used to characterize both reduced and oxidized forms of poly(indole-5-carboxylic-acid). Assignments of the vibrational modes were proposed by comparison of the vibrational spectra of polyindole and polycyanoindole. The polymerization sites correspond to the 2 and 3 carbon positions of the pyrrole cycle. In the oxidized form of the polymer, the NH group is deprotonated while the quinoid form is present between the pyrrole rings.