Study of Environment and pH Effects on the Spectral Behavior of Arylazobenzylidene Dyes

In this study, four arylazobenzylidene dyes (a-d) were synthesized with excellent yields in two steps using Knoevenagel condensation and azo-coupling reactions. Absorption spectra of these dyes with different substituents were investigated in organic solvents as a function of solvent polarity. The spectral features of synthesized arylazobenzylidene dyes were described according to azo-hydrazone tautomerism as well as the solvatochromic characteristic of the approved tautomer. The nature and degree of solute-solvent interactions were illustrated using Kamlet-Taft multi-parameter polarity scales. The effects of acid-base on the UV-visible absorption spectra of the dyes were reported. In addition, different absorption characteristics were observed for these dyes in pure diethanolamine.