The Nature of Charge Carriers in Polymeric Complexes of Nickel with Schiff Bases Containing Electron-Withdrawing Substituents

Abstract

The data on polymeric complexes of nickel with salen-type Schiff bases containing electron-withdrawing nitro groups in ligand’s aromatic fragments are acquired by an in situ technique based on collecting electron paramagnetic resonance spectra simultaneously with absorption spectra in the UV, visible, and near IR regions in the course of oxidation-reduction of a polymer film on the surface of an optically transparent electrode under conditions of cyclic voltammetry. Based on the combined analysis of spectroscopic and electrochemical data, it is shown that as the potential of the polymer-modified electrode shifts in the positive region, the different types of charge carriers successively appear in the system (phenoxyl radical cations, radical pairs, and dications). The results obtained suggest that the positive charge can be delocalized either between aromatic rings in monomer fragments or between fragments of neighboring polymer chains.