Studies on some novel Schiff-base complexes in solution and solid state

Author： Nair M. Sivasankaran Kumari S. Suda Neelakantan M. A.

ISSN： 0095-8972

Source： Journal of Coordination Chemistry, Vol.60, Iss.12, 2007-06, pp. : 1291-1302

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Abstract

In solution Schiff-base complexes of stoichiometry MAB, MAB2 or MA2B2 have been detected in the Co(II), Ni(II), Cu(II) and Zn(II)-o-vanillin (o-van) [A]-L-valine (val), L-glutamine (gln) and L-histidine (his)(B) systems. The results suggest that in the M-o-van-val/gln systems, the Schiff-base ligand (AB) is tridentate in M(AB) complexes, while (AB) is tetradentate in his systems. MAB2 species can be represented as M(AB)(B), where the mode of coordination of (AB) would be similar to that in the M(AB) species. The MA2B2 complex can be represented as M(AB)2, where (AB) is tridentate in all the systems. The stabilities of complexes follow the Irwin-Williams order of stability. MAB complexes were isolated and conformed by characterization data. Conductance studies indicate that all complexes are non-ionic. Magnetic susceptibility and electronic spectral data suggest a tetrahedral structure in Co(II) and Ni(II)-o-van-val/gln and Ni(II)-o-van-his systems and square-planar structure in Co(II)-o-van-his and Cu(II)-o-van-val/gln/his systems for the MAB species. The IR spectral data indicate the tri and tetradentate binding of (AB) in the M(AB) complexes, respectively, in M(II)-o-van-val/gln and M(II)-o-van-his systems. Antimicrobial activity of the ligand and its Cu(II) complexes has been studied; Cu(II) complexes have higher activity than that of the ligand and control.