Abstract

Schiff base ligand derived by condensation of 2-hydroxy-1-naphthaldehyde and 2,3-diaminophyridine was synthesized. Its complexes of Co(II) and Zn(II) were synthesized. The Schiff base and its complexes were characterized by solubility test, melting point/decomposition temperature determination, molar conductance measurement, spectrophotometric analysis, magnetic susceptibility measurement. The ligand and the complexes were obtained in appreciable yield (ligand 81.86%, Co(II) complex 71.60% and Zn(II) complex 71.54%). The melting point of the ligand 1800C and the decomposition temperatures of the complexes 2100C and 2000C for the Co (II) and Zn(II) complexes respectively, indicate that the compounds are stable. The molar conductance (Co(II) 11.96 -1cm2 mol–1 and Zn(II) 5.65 -1cm2 mol–1 respectively) of the complexes measured is low, indicating their non-electrolytic nature, magnetic susceptibility measurement showed that the Co(II) complex is paramagnetic while Zn(II) complex is diamagnetic. From the spectrophometric and gravimetric analyses, the complexes are in the ratio of 1:2 metal to ligand. The ligand and its metal(II) complexes were screened for antibacterial and antifungal activities against some bacterial (Escherichia coli, Salmonella typhi, and Staphylococcus aureus) and fungal isolates (Aspergillus niger, Aspergillus flavus and Candida albican). The result reveals that the complexes have higher antimicrobial activity than the ligand.

Key words: Synthesis, Schiff base, Complexes, Characterization, antimicrobial