Spectral Characterisation and Computational Studies of Some New 3-(2-Arylhydrazineylidene) Benzo[H]Quinolin-2,4(1h,3h)-Dione Dyes

4-hydroxyquinolin-2(1h)-one (2,4-dihydroxyquinoline) and n-butyl-4-hydroxyquinolin-2(1h)-one were respectively employed for the synthesis of c.i. pigment yellow 7 and c.i. mordant yellow 30. more recently, a wide range of substituted 4-hydroxyquinolin-2(1h)-ones have been synthesized and used as coupling components for the preparation of 3-aryl-azo disperse dyes in order to investigate their biological activities [1-2]. the visible absorption studies clearly indicated that the lactam moiety of quinoline-2(1h)-one section has strong electron withdrawing nature and the dyes bearing electron donating groups on diazo components show bathochromic shifts with respect to unsubstituted and electron-withdrawing substituents. herein, a series of substituted anilines with different electron releasing and electing accepting substituents have been diazotized and coupled with 4-hydroxybenzo[h]quinoline-2(1h)-one in basic ethanol solution at 0-5°c.the structures of these newly synthesized azo dyes were assigned by ir, 1h nmr and mass spectroscopic analyses. 1h nmr spectroscopic studies implied that the dyes exist as keto-hydrazo-keto tautomeric form in solution state. the uv-vis absorption spectra of the dyes in solvents with different polarities showed no distinct change owing to their strong intramolecular hydrogen- bonding interactions. the results also showed that λmax of hydroxyquinoline based azo dyes are mostly independent of the nature of the substituents bonded with phenyl rings of the diazo components. the effects of acid and base on the visible absorption spectra of the of the dyes in ethanol were also studied and showed that the spectral changes are clearly dependent upon the protonation-deprotonation of the dye molecules.

Spectral characterisation and computational studies of some new 3-(2-arylhydrazineylidene) benzo[h]quinolin-2,4(1H,3H)-dione dyes

4-Hydroxyquinolin-2(1H)-one (2,4-dihydroxyquinoline) and N-butyl-4-hydroxyquinolin-2(1H)-one were respectively employed for the synthesis of C.I. Pigment Yellow 7 and C.I. Mordant Yellow 30. More recently, a wide range of substituted 4-hydroxyquinolin-2(1H)-ones have been synthesized and used as coupling components for the preparation of 3-aryl-azo disperse dyes in order to investigate their biological activities [1-2]. The visible absorption studies clearly indicated that the lactam moiety of quinoline-2(1H)-one section has strong electron withdrawing nature and the dyes bearing electron donating groups on diazo components show bathochromic shifts with respect to unsubstituted and electron-withdrawing substituents. Herein, A series of substituted anilines with different electron releasing and electing accepting substituents have been diazotized and coupled with 4-hydroxybenzo[h]quinoline-2(1H)-one in basic ethanol solution at 0-5°C.The structures of these newly synthesized azo dyes were assigned by IR, 1H NMR and Mass spectroscopic analyses. 1H NMR spectroscopic studies implied that the dyes exist as keto-hydrazo-keto tautomeric form in solution state. The UV-vis absorption spectra of the dyes in solvents with different polarities showed no distinct change owing to their strong intramolecular hydrogen- bonding interactions. The results also showed that λmax of hydroxyquinoline based azo dyes are mostly independent of the nature of the substituents bonded with phenyl rings of the diazo components. The effects of acid and base on the visible absorption spectra of the of the dyes in ethanol were also studied and showed that the spectral changes are clearly dependent upon the protonation-deprotonation of the dye molecules.