Preparation and Characterization of Some New Azoxine S Azo Dyes

Abstract

New azoxine S dyes were prepared by coupling some diazotized sulpha
drugs with 8-hydroxyquinoline-5-sulphonic acid. Their structures were investigated
using elemental analysis, IR and NMR absorption spectra and
thermogravimetric analysis. The UV and visible absorption spectra of the
prepared compounds were scanned in ethanol and the absorption bands
were assigned to their electronic transitions. The UV and visible spectra
were scanned also in different solvents of varying polarities and the relations
between different solvent parameters and λ_max were plotted, but no
linear relations were obtained; so there is no single parameter that affects
spectral shifts. The ionization constants of the ionizable groups of the
prepared azoxine S dyes were calculated spectrophotometrically using the
half height and limiting absorbance methods.