Optically active polypyrroles containing chiral dopant anions

Abstract

A reexamination of the electropolymerization of pyrrole in the presence of (+)- and (–)-camphorsulfonic acid (HCSA) has shown that, contrary to a recent report, the deposited PPy·HCSA films do not possess macroasymmetry in their polypyrrole chains. In contrast, similarly deposited PPy·(+)-tart, PPy·(–)-tart, PPy·(+)-mand and PPy·(–)-mand films (tart = tartrate ion; mand = mandelate ion) exhibit weak circular dichroism bands in the visible region, confirming partial chiral induction in their polypyrrole backbones due to the presence of the chiral dopant anions during the electropolymerizations. The much weaker chiral induction compared to related electropolymerizations of aniline is ascribed to the absence of polar groups on the polypyrrole backbone to facilitate interaction with the chiral dopant.