RRS characterization of selected oligomers of polyaniline in situ spectroelectrochemical study

摘要

Electrochemical, optical and vibrational properties of two oligomeric model compounds of emeraldine salt (ES), the only electrically conducting form of polyaniline, in nonaqueous solution are studied. The phenyl-end-capped dimer and tetramer ofleucoemeraldine base are electrochemically oxidized in acetonitrile solution and the electrogenerated species are investigated using spectrophotometry and Resonance Raman Scattering (RRS). In situ resonance Raman study of the oligomers reveals theappearance of the vibrational bands characteristic of the semiquinoid units, and in particular of the CN bond intermediate between the single and double CN bonds which are strongly resonantly enhanced with a red excitation line. The vibrationalassignments of the fundamental modes of the electrogenerated species are reported and compared with those of the corresponding polymeric form. Our Raman results provide very interesting information not only about the vibrational properties of emeraldinesalt but also about its electronic configuration.