Influence of Electrochemical Polymerization Temperature on the Chiroptical Properties of (+)-Camphorsulfonic Acid-Doped Polyaniline

摘要

The chiroptical properties of electrochemically deposited emeraldine salt PAn centre dot (+)-HCSA (HCSA = 10-camphorsulfonic acid) films have been found to vary markedly with the temperature employed during polymerization.The circular dichroism spectra of such films grown at >40 deg C are inverted compared to the spectra of analogous films deposited at temperatures <=25 deg C,indicating an inversion of conformation for the polyaniline chains.These observations are rationalized in terms of a temperature-induced interconversion between the two diastereomeric emeraldine salt products from the doping of the growing polyaniline chains by the chiral (+)-CSA~- anion.The marked temperature dependence of the diastereoselectivity highlights the importance of employing a fixed temperature during the electrosynthesis of optically active polyanilines.