RESONANCE RAMAN INVESTIGATION OF CHARGE-TRANSFER COMPLEXES BETWEEN A TRITYL CATION (CRYSTAL VIOLET) AND SULFONATED AZO DERIVATIVES

For the first time, a study of metachromasia by resonance Raman spectroscopy has been carried out; the crystal violet cation, well known for giving rise to this phenomenon, was studied in the presence of four sulfonated azo dyes. Through a relevant use of excitation frequencies corresponding to the new electronic absorption bands resulting from the interaction of the compounds, we clearly showed the formation of charge transfer complexes. Comparisons between the vibrational spectra of free compounds and of complexes enabled us to specify the changes experienced by the sulfonated azo compounds (donors) and the crystal violet (acceptor), as well as the vibrational characteristics of the charge transfer complexes. © 1979 American Chemical Society.