Preparation, characterization and antimicrobial studies of some metal(II) complexes of a schiff base. derived from 2,3 diaminopyridine and 2-hydroxy -1- naphthaldehyde

Abstract

Schiff base derived from condensation of 2,3 diaminopyridine and 2-hydroxy -1-naphthaldehyde and its Mn(II), Ni,(II) and Cu(II) complexes have been synthesized. The Schiff base and its complexes were characterized by solubility test, melting point/decomposition temperature determinations, molar conductance measurement, spectroscopic and magnetic susceptibility measurement, and gravimetric method of analysis. The ligand is dark green with melting point of 180°C and percentage yield of 81.86%. The percentage yields of the complexes were in the range of 55.19-74.85%, the decomposition temperatures of the complexes were in the range of 200 – 292°C. Their molar conductance values (4.84-13.36 ohm^-1 cm² mol^-1) indicate that all the complexes are non-electrolytes. Magnetic moment values of the complexes showed that all are paramagnetic. A tetrahedral geometry was proposed for Mn(II) complex while square planar was proposed for Co(II) and Ni(II) complexes. The ligand and it’s metal (II) complexes were screened for antibacterial and antifungal activities against some bacterial (Escherichia coli, Salmonella typhi, and Staphylococcus aureus) and fungal isolates (Aspergillus flavus, Aspergillus niger, Candida albican). The inhibition properties showed that the complexes have higher antimicrobial activity than the ligand which could be attributed to chelation, however lower than the standards used.

KEY WORDS: Schiff base, Transition metal complex, spectral study, gravimetric analysis,
Antimicrobial study.