Potential controlled electrochemical assembly of chiral polyaniline with enhanced stereochemical selectivity

Chiral polyaniline with absolute sterochemical selectivity in the order of magnitude 10−2 is electrochemically assembled onto various electrodes in the presence of chiral inducing agent (1S)-(+)-10-camphorsulfonic acid ((S)-(+)-CSA) or (1R)-(−)-10-camphorsulfonic acid ((R)-(−)-CSA). The polymerizing potential dependence of the absolute stereochemical selectivity of the resultant chiral polyaniline is investigated in detail. The one-step (low potential at 0.7 V) and two-step (potential higher than that of aniline oxidation potential of the electrode applied first in the short period of time and then low potential at 0.7 V applied in the relatively long time) potential control strategies are developed for the different conducting substrates in order to produce chiral polyaniline with enhanced absolute stereochemical selectivity. The possible mechanism on polymerizing potential dependence of chiral polyaniline with enhanced absolute stereochemical selectivity is discussed. The structure and morphology of the resultant polyaniline films are investigated by scanning electron microscopy (SEM). The strong mirror images of the circular dichroism (CD) spectra for the (R)-(−)-CSA and the (S)-(+)-CSA doped polyaniline films suggest that the obtained chiral polyaniline films are enantioselective.