Resonance Raman characterization of poly(benzidine) in different oxidation states

Abstract In this paper, the structure of poly(benzidine) (PBZ) in different oxidation and protonation states is investigated by Raman spectroscopy (resonance Raman and FT-Raman) at several laser lines. In addition, all vibrational data is supported by DFT calculations. The resonance Raman spectra of doped and undoped PBZ show similar set of bands, however the doped PBZ show an increase of bands related to protonated segments (dications and radical cations) at 1147, 1332 and 1598 cm−1. The UV–vis-NIR and Raman confirm the formation of reduced form of PBZ, where the azo groups dominate. For all PBZ forms is not seen changes of the band position with the laser line (Raman dispersion). Probably, this is an indication of low conjugation between the segments in the polymeric backbone and justify the lower conductivity observed for PBZ than measured for polyaniline (PANI), a similar conducting polymer. Finally, the oxidation of PBZ with strong oxidants probably destroy the azo and phenazine units into PBZ backbone.