SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL STUDIES OF HETEROLEPTIC CO(II), NI(II), CU(II) AND ZN(II) COMPLEXES OF N-(2-HYDROXYBENZYLIDENE)PYRAZINE-2-CARBOXAMIDE

Title: SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL STUDIES OF HETEROLEPTIC CO(II), NI(II), CU(II) AND ZN(II) COMPLEXES OF N-(2-HYDROXYBENZYLIDENE)PYRAZINE-2-CARBOXAMIDE

Author(s): Chioma Festus

ABSTRACT

The divalent Co, Ni, Cu and Zn complexes with the Schiff base ligand; N-(2-hydroxybenzylidene)pyrazine-2-carboxamide (HL) and 2,2’ bipyridine have been synthesized. The HL ligand and its metal (II) complexes were all synthesised using methanolic solvent at 55oC and constant stirring. The resulting heteroleptic complexes were characterized by magnetic moment and conductivity measurements, IR and UV-visible spectral studies. The Schiff base ligand, HL acts as a bidentate monobasic ligand, coordinating through the azomethine nitrogen and deprotonated napthol oxygen atoms, while the bidendate 2,2’ bipyridine ligand (L’) coordinated  through its aromatic nitrogen atoms with the metal ions respectively. The heteroleptic metal complexes were non-electrolytic in dimethylsulphoxide (DMSO). The analytical and spectral data indicates that all the complexes were mononuclear, covalent, and octahedral and coordinated with the ligands in 1:1:1 molar ratio respectively. The in vitro antibacterial activity of the synthesized compounds  were investigated against strains of Bacillus cereus, Proteus mirabilis, Escherichia coli, Staphylococcus aureus, Klebsilla oxytoca and Pseudomonas aeruginosa. The antibacterial activity of the Schiff base and the complexes compared favourably with that of standard drug, streptomycin against Bacillus cereus, Proteus mirabilis and Pseudomonas aeruginosa. The studied divalent cobalt and copper complexes had the best antibacterial activity against the screened microbes with inhibitory zone range of 23.3–28.3 mm.

Keywords: Pyrazine, Schiff base, Heteroleptic, Bidendate, In-Vitro and Octahedral geometry
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