ESR and magnetic properties of electrically conducting metallophthalocyanine polymers

Abstract

Polymeric metallophthalocyanines of Cu, Ni, Co in which benzene rings are shared in common with the macrocyclic phthalocyanine rings containing peripheral carboxylic groups have been synthesized and their electrical conductivities are shown to increase from 5 to 8 orders of magnitude by thermal treatment. The cobalt polymer exhibits greater conductivity than its nickel or copper analogs. The heated polymers show very broad electron spin resonance (ESR) signals and large paramagnetic susceptibilities. The bulk magnetic susceptibility of these polymers shows Curie-like behavior when the samples are heated from room temperature to 473 K. This is explained on the basis of coexistence of fixed mobile and conduction electron spins in the system and the interaction of the soliton type defects present in these polymers with the polymeric network to give dipolar charge carriers. This is also supported by the decrease in ESR intensity with increasing temperature when the samples are heated in the ESR cavity. The effect of the presence of unpaired electrons on the d shell of the central metal atoms on the line width and the line shape of the ESR spectra is also explained.