STRUCTURAL CHARACTERIZATION OF SOME QUINOLIN-8-OL-CONTAINING AZO DYES IN SOLID AND SOLUTION-STATE AS PROBED BY RESONANCE RAMAN, FOURIER-TRANSFORM IR AND ELECTRONIC SPECTROSCOPIC TECHNIQUES

Some 5-(aryl)azoquinolin-8-ol derivatives were studied by resonance Raman, Fourier transform IR and electronic spectroscopic techniques. Analysis of vibrational and electronic spectra was used to determine the azo and hydrazone forms in both the solid and solution states. In the solid state, the compounds remain dominantly in one form and the characteristic bands due to each resonating form were identified Various structural motifs for protonated, neutral and deprotonated states were proposed based on pH-dependent studies. The effect of H-bonding in stabilizing a particular type of structure is also discussed.