SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL STUDIES OF NI(II), CU(II), AND ZN(II) COMPLEXES WITH A SCHIFF BASE DERIVED FROM 3-FORMYLCHROMONE AND BENZOHYDRAZIDE

Abstract

A Schiff base ligand derived from condensation of 3-formylchromone and benzohydrazide was synthesized. Its Ni(II), Cu(II) and Zn(II) complexes were subsequently prepared and characterized. The characterization techniques included: molar conductivity measurement, magnetic susceptibility, IR spectroscopy, AAS spectroscopy, elemental analysis and thermal measurements. The Schiff base gave a melting point of 165⁰C, while the complexes decomposed in range of (195-230)⁰C indicating good thermal stability. The molar conductance values of the complexes ranging from (3.08-5.71) Ω^-1cm²mol^-1 suggested that all complexes are non-electrolytic in nature. The IR spectrum of the free ligand displayed a band at 1633cm^-1 attributed to the azomethine   (-C=N-) stretching vibration. This band shifted to lower wavenumbers (1603 -1655) cm^-1 in the spectra of the complexes, confirming coordination through the azomethine Nitrogen. Magnetic susceptibility measurements indicated that all the complexes except that of Zn are paramagnetic and exhibited tetrahedral geometry. Elemental analysis data were consistent to 1:1 metal to ligand stoichiometry. Furthermore, the Sch

iff base and the complexes were evaluated for antibacterial and antifungal activity against some pathogenic microorganisms. Some of the compounds showed notable activity, while others exhibited no significant effect.