Comparative study on the structural changes in leucoemeraldine and emeraldine base upon doping by perchlorate

Abstract

The changes in the structure of leucoemeraldine (LM) and emeraldine (EM) base upon doping by perchlorate anions are studied by X-ray photoelectron spectroscopy (XPS) and infrared (IR) absorption spectroscopy. In the case of LM, interactions of the amine nitrogens with the perchlorate anions result in a nitrogenonium ion structure analogous to that arising from the protonation of imine nitrogens in EM by HCl except the chloride anion in the latter has been replaced by the perchlorate anion. A small amount of partially ionic and covalent chlorine is also incorporated in the LM-perchlorate complexes. The maximum electrical conductivity that is achieved in these complexes is about 4 S/cm. In contrast, the maximum conductivity of the EM-perchlorate complexes is three orders of magnitude lower. The interactions of perchlorate anions with EM base result in the preferential disappearance of the imine units over the amine units.