Enantioselective electropolymerization of aniline in the presence of (+)- or (-)-camphorsulfonate ion: a facile route to conducting polymers with preferred one-screw-sense helicity

M. R. Majidi, University of Wollongong
L. A. Kane-Maguire, University of Wollongong
G. G. Wallace, University of Wollongong

Abstract

The first and remarkably facile synthesis of optically active polyaniline has been achieved via the enantioselective electropolymerization of aniline on indium-tin-oxide-coated glass electrodes in aqueous solution containing (1S)-(+)- or (1R)-(-)-10-camphorsulfonic acid (HCSA). The dark green films of conducting polyemeraldine salt formed under electrostatic conditions (+ L1 V versus Ag/AgCl) exhibited strong circular dichroism (c.d.) spectra typical of polymers possessing helical chirality. The quantitative reversal of the c.d. spectrum of the salt grown in (+)-HCSA as opposed to (-)-HCSA suggests that electropolymerization is highly enantioselective, with one helical screw of the polymer chain being preferentially produced depending on the hand of the CSA- anion incorporated. The ready electrosynthesis of optically active polyanilines should facilitate studies of their use in asymmetric synthesis and in chiral chromatography.