Synthesis and spectroscopic properties of new azo-dyes and azo-metal complexes derived from barbituric acid and aminoquinoline

Two new azo-dyes, 5-(quinoly-8-azo)pyrimidine-2,4,6-trione (L-1) and 5-(quinoly-8-azo)-1,3-dimethylpyrimidine-2,4,6-trione (L-2) were prepared by linking 8-aminoquinoline to barbituric acid and 1,3-dimethylbarbituric acid through diazo-coupling reactions. Reaction of new azodyes with Cu(II) or Ni(II) salts and unidentated ion gave mononuclear complexes with general stoichiometry [MLX], [M: Ni(H) or Cu(II); X: NO3-, SCN-, CN- or N-3(-)]. On the other hand, two kinds of cobalt(H) complexes with different stoichiometries were prepared. Reaction of azo-dyes with Co(AcO)(2) with 2:1 molar ratio gave azo complexes with stoichiometry Co(L)(2) while reaction of cobalt salts with tridentate azo-dyes, bidentate ligand, 1, 10-phenanthroline (B), and unidentate ion (X: NO3-, SCN-, CN- or N-3(-)), mixed hard-soft donor sets, produced a new set of complexes with general stoichiometry CoLBX. The structures of both azo-dyes and their complexes were identified by elemental analyses, FTIR, H-1 NMR, UV-vis, magnetic susceptibility and mass spectral data. The elemental analyses and spectral data indicate that azodyes act as monobasic O,N,N '-tridentate ligand. The difference in absorption maximum from ligands to metal complexes was also studied. (c) 2005 Elsevier Ltd. All rights reserved.