The First Products of Aniline Oxidation – SERS Spectroelectrochemistry

There are different opinions on the first products of aniline oxidation throughout the scientific community. While electrochemists basically accept only linear oligomers with repeating units joint in para positions, chemists have proposed formation of various branched and polycyclic oligomers. It was also suggested that one of these structures, N-phenyl-phenazinium cation, is responsible for the adherence of polyaniline films to substrates. In this work, a surface enhanced Raman spectroscopic and spectroelectrochemical analysis of the species adsorbed onto gold surface in aniline-containing solution at pH 1 and 5 is presented. The influence of the pH value on the oligomer structure is declared. The results are discussed in the context of linear and branched/phenazine-like aniline oligomers. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim