Abstract:

（E）-1-ethyl-6-hydroxy-4-methyl-5-（（4-nitrophenyl）diazenyl）-2-oxo-1，2-dihydropyridine-3-carbonitrile and （E）-5-（（2，4-dinitrophenyl）diazenyl）-1-ethyl-6-hydroxy-4-methyl-2-oxo-1，2-dihydropyridine-3-carbonitrile， namely D1 and D2 were synthesized， color performance in solvents， DMF and CH₂Cl₂， as well as polyester and polyaimde fabrics are studied to investigate azo-hydrazone tautomerism behaviors of disperse dyes containing pyridone group. The visible absorption spectrophotometry behaviors in solvents are studied， and the heterochromic dyeing performance on polyethylene terephthalate （PET） and polyamide （PA） fabrics is also compared. To reveal azo-hydrazone tautomerism of pyridone disperse dyes induced by circumstances， Gaussian simulation is applied to give optimized geometries， as well as absorption spectrum in solvent and non-solvent environment. Nuclear magnetic resonance （¹H NMR） spectrum shows that the disperse dyes with pyridinone structure exist as azo form in polar solvents and hydrazone tautomer in non-polar solvents. The dyeing performance and quantum calculation show that the dyes exist in hydrazone form on PET fabric and azo structure in PA fabric. Pyridone disperse dyes show excellent light fastness on PET fabrics， but poor light fastness on PA fabrics， which is attributed to azo-hydrazone tautomerism of the dyes.

Key words: Pyridone, Azo-hydrazone, Heterochromia, Gaussian simulation, Light fastness