Synthesis, characterization and antimicrobial studies on Schiff base derived from 2-aminopyridine and 2-methoxybenzaldehyde and its cobalt (ii) and nickel (ii) complexes

Abstract

A Schiff base ligand has been synthesized by the condensation of 2-aminopyridine and 2- methoxybenzaldehyde. Metal complexes of the Schiff base were prepared by the reaction of the Schiff base and metal (II) chlorides of cobalt and nickel in ethanol. The complexes were isolated, washed and dried. The Schiff base is pale yellow, while cobalt and nickel complexes are blue and light green respectively. The Schiff base and its metal (II) complexes were characterized by solubility test, melting and decomposition temperature determination, FTIR, magnetic susceptibility, molar conductance gravimetric analysis and UV spectroscopy. Solubility test carried on the Schiff base and the complexes showed that they are all soluble in DMSO and DMF, but insoluble in water. From the FTIR result, a peak at 1577cm^-1 is assigned to the azomethine of the Schiff base which shifted to 1637 and 1622 cm^-1 in cobalt (II) and nickel (II) complexes respectively. The complexes are high spin, non electrolytic in nature and have high thermal stability. Job’s method of continuous variation suggests 1:2 metal to ligand ratio. The Schiff base is inactive against Staphylococcus aureus at all concentrations while the complexes were found to be active and the activity increases with increase in concentration. The Schiff base and its complexes are found to be active against E. coli at all concentrations. The anifungal study revealed that the Schiff base and its complexes are active against Candida albican at all concentrations, but inactive against
Mucor specie at all concentrations.

KEY WORDS: 2-aminopyridine, 2-methoxybenzaldehyde, Ligand, Characterization, Antimicrobial activity