Synthesis, physicochemical and in-vitro antibacterial properties of some novel metal(II) complexes of 3-{[(6-methoxypyridin-3-yl)imino]methyl}-5-nitrophenol

Abstract

The Schiff base, 3-{[(6-methoxypyridin-3-yl)imino]methyl}-5-nitrophenol, formed by condensation of 5-amino-2-methoxypyridine and 2-hydroxy-5-nitrophenol; and its metal(II) complexes{where M = Mn, Co, Ni, Cu, Zn, Pd} have been synthesized and characterized by %metal, melting points, IR and electronic spectroscopies. The complexes analyse as [ML(NO3)] with the exception of the Ni(II), Cu(II) and Pd(II) complexes which analyse as [MLCl(H2O)] respectively. The IR data confirm that the Schiff base coordinates via the imine nitrogen and phenol oxygen atoms; while the electronic data support a 4-coordinate tetrahedral/squareplanar geometry for the metal complexes. The metal complexes are air stable solids, which melt/decompose on heating in the temperature range 228-390 oC; while the metal–free Schiff base melts at 208-210 oC. The in-vitro antibacterial studies reveal that the Schiff base, its Co(II) and Zn(II) complexes have a broad-spectrum antibacterial activity against Bacillus cereus, Pseudomona aeuriginosa, Staphylococcus aureus and Proteus mirabilis with inhibitory zones range of 14.0-22.0mm.