The Question of Solid-State Electron Transfer in Contact Charging between Metal and Organic Materials

This report describes charging studies between iron beads and powders of some aromatic anil derivatives that were previously used to study the mechanism of charging. Our results show that the charge responses to substituent effects and linear correlations are observed between the charge and both the oxidation potentials and the basicity of the compounds. These parallel relationships question the validity of previous conclusions proposing electron transfer as the basis for charging. We also find that the charging is accompanied by a considerable amount of material transfer to the iron beads, which points to the inadequacy of selecting these materials for mechanistic studies. The need to invoke electron transfer to explain the charge is questioned based on the relative energetics of the proton- and electron-transfer process. © 1991, American Chemical Society. All rights reserved.