SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL STUDIES OF 3-BROMOBENZALDEHYDE NICOTINIC ACID HYDRAZONE AND IT’S Co(II), Cu(II), Mn(II) AND Ni(II) COMPLEXES

Abstract

Acyl hydarazones and other hydrazones derivatives are of immense biological importance as a result of their antibacterial, antifungal, antiinflammatory properties and coordination Chemistry. The ligand was prepared by refluxing nicotinic acid hydrazide and 3-bromobenzaldehyde in ethanol, the complexes were synthezed by mixing ethanolic solutions of the metal salts with the hydrazone. The ligand and complexes were characterized on the basis of uv-visible, FTIR, melting point, conductivity, magnetic susceptibility, metal analysis and mole ratio, antimicrobial activities were determined. The ligand and complexes formed are high melting point crystalline solids. Thermodynamic stability study showed that the complexes are stable with stability constants between 2.84 x 105 – 2.21 x 107 while the solution studies gave 1:2 metal to ligand ratio. Infrared spectra data are diagnostic of bidentate coordination of the ligand via carbonyl oxygen and azomethine nitrogen atoms as result of the negative shift in the (C=O) and (C=N) bands. Effective magnetic moment of the complexes is 5.62 B.M, 4.02 B.M. and 1.81 B.M. for Manganese, Cobalt and Copper complexes respectively, the nickel complex is diamagnetic. Electronic spectra of the ligand indicate n * transitions, transition in the manganese complex is spin and orbital forbidden with very low molar absorptivity, nickel complex gave two bands assigned to 3A2g(F) 3T1g(F) and 3A2g(F) 3T1g(P) transition, cobalt complex gave one electronic band assigned to 4T1g(F) 4A2g transition. Copper complex gave one band, assigned to 2Eg 2T2g transition. On the basis of magnetic and electronic spectral of the isolated complexes octahedral geometry has been proposed for the Mn(II), Co(II) and Cu(II) complexes and square planar for the Ni(II) complex. The activities of the complexes against most of the microorganisms were enhanced compared to those of their parent ligand, with some promising potential when compared to the control drugs.