Experimental and theoretical UV-Vis spectral study of some arylazo pyridone dyes in amide solvents

Abstract

Spectral properties of ten 5-(substituted phenylazo)-3-cyano-1-ethyl-6-hydroxy-4-methyl-2-pyridones were investigated in formamide and N,N-dimethylformamide (DMF) by combining experimental study and density functional theory (DFT). In these two solvents, equilibrium between hydrazone and anionic forms is confirmed both experimentally and theoretically. Relative position of the absorption maxima of hydrazone and anion forms is highly affected by the substitution pattern in the phenyl ring. Theoretical absorption energies showed good agreement with experimental data.