A study of Solvatochromism in diazonium coupling products of 6-flouro 4-hydroxyl-2-quinolone

6-flouro 4-hydroxyl-2-quinolone was synthesized from cyclocondensation of corresponding dianilide and subsequently used as a potent coupling component with some diazotized aromatic amines. The prepared azo dyes were characterized by UV-vis, FT-IR, 1H NMR spectroscopic techniques and elemental analysis. The solvatochromism of dyes was evaluated with respect to wavelength of maximum absorption (λmax) in six solvents: acetic acid, methanol, chloroform, acetonitrile, dimethyl sulfoxide and dimethyl formamide. The color of the dyes is discussed with respect to the nature of substituents on the benzene ring. The effects of acid and base on the visible absorption spectra of the dyes were also reported. Ionization constants, pKa, for these dyes were determined in 80 vol.% ethanol-water medium at room temperature and correlated with the substituent constant, σx.

Research highlights►Synthesis of 6-flouro 4-hydroxyl-2-quinolone ►preparation of some quinolone based azo dyes ►evaluation of solvathochromic properties ►acidic dissociation constants were measured.