Spectroelectrochemistry of conducting polypyrrole and poly(pyrrole–cyclodextrin) prepared in aqueous and nonaqueous solvents

Abstract

Conducting polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl-β-cyclodextrin) [poly(Py-β-DMCD)] films were prepared by electrode potential cycling on a gold electrode in aqueous and nonaqueous (acetonitrile) electrolyte solutions containing lithium perchlorate. The resulting products were characterized with cyclic voltammetry, in situ UV–Vis spectroscopy, and in situ conductivity measurements. For the electrosynthesis of poly(Py-β-DMCD), a (1:1) (mole–mole) (Py-β-DMCD) supramolecular cyclodextrin complex of pyrrole previously characterized with proton NMR spectroscopy was used as starting material. A different cyclic voltammetric behavior was observed for pyrrole and the poly(Py-β-DMCD) complex in aqueous and nonaqueous solutions during electrosynthesis. The results show that in both solutions in the presence of cyclodextrin, the oxidation potential of pyrrole monomers increases. However, the difference of oxidation potentials for films prepared in aqueous solution is larger than for the films prepared in nonaqueous solution. In situ conductivity measurements of the films show that films prepared in acetonitrile solution are more conductive than those synthesized in aqueous solutions. Maximum conductivity can be observed for PPy and poly(Py-β-DMCD) films prepared in nonaqueous solution in the range of 0.10 < EAg/AgCl < 0.90 V and 0.30 < EAg/AgCl < 0.90 V, respectively. In situ UV–Vis spectroelectrochemical data for both films prepared potentiodynamically by cycling the potentials from −0.40 < EAg/AgCl < 0.90 V in nonaqueous solutions are reported.