Fluorescent azo disperse dyes from 3-(1,3-benzothiazol-2-yl)naphthalen-2-ol and comparison with 2-naphthol analogs

Five novel fluorescent azo disperse dyes were synthesized using different diazotized aromatic amines followed by coupling with 3-(1,3-benzothiazol-2-yl)naphthalen-2-ol. These dyes were characterized by FT-IR, 1H NMR and mass spectroscopy. These azo disperse dyes were applied on polyester and their fastness properties were evaluated. A parallel series of dyes using 2-naphthol in place of benzothiazolyl were made to investigate the effect of benzothiazolyl moiety on the fastness properties. This investigation showed that the dyes containing benzothiazolyl residue have better fastness properties than that of the azo disperse dyes based on 2-naphthol. Effect of pH on photo physical properties was also studied.

► Synthesis and characterization of dyes from 3-(1,3-benzothiazol-2-yl)naphthalen-2-ol. ► Fastness properties were studied and compared with 2-naphthol based disperse azo dyes. ► Enhanced photo stability was explained by ESIPT phenomenon. ► Effects of pH and solvent polarity on photo physical properties were also studied. ► Due to presence of ESIPT, disperse azo dyes fluoresce in solvents with lower intensity.