Abdullahi Ola Rajee1*, Abdulbasit Anoze Aliyu2, Halimah Funmilayo Babamale3, Amudat Lawal4, Sheriff O. Ayinla4, Wahab A. Osunniran5 & Joshua A. Obaleye1
1 Department of Chemistry, University of Ilorin, Ilorin, Nigeria
2 Department of Pure and Industrial Chemistry, Kogi State University, Anyigba, Kogi, Nigeria
3 Department of Industrial Chemistry, University of Ilorin, Ilorin, Nigeria
4 Department of Chemical and Geological Sciences, Al-Hikmah University, Ilorin, Kwara, Nigeria
5 Department of Chemical, Geological and Physical Sciences, Kwara State University, Malete, Kwara, Nigeria
Mn(II), Cu(II) and Zn(II) complexes of methionine with polypyridine co-ligand formulated as [Mn(MET)(bpy)2] (1), [Cu(MET)(bpy)2] (2) and [Zn(MET)(bpy)2] (3) (MET = methionine, bpy = 2,2-bipyridine) were prepared and characterized by elemental analysis and spectroscopic techniques(Infrared, Electronic and ESI-MS). Electronic absorption spectra data of the complexes are characteristic of octahedral structures. The infrared data revealed that the ligand (MET) behaved as a bidentate anionic ligand. It coordinated to the metal ions via oxygen and nitrogen atoms with exhibiting peaks for υ(NH2) at 3365 cm-1, υas(COO-) and υas(COO-) at 1410 and 1621 cm-1 respectively. The 2,2-bipyridine coordinated to the metal center characteristically via the polypyridyl nitrogen. The compounds showed moderate solubility in distilled water and in some common organic solvents. In vivo evaluation of the antimicrobial activities of the metal complexes and the ligands showed greater activity against some micro-organisms when compared to the parent compounds. For instance, MET has a highest growth inhibition zone diameter of 14 mm whereas (1), (2), (3) has a diameter of inhibition zones at 23, 28 and 28 mm against C. albicans, A. niger and C. albicans respectively.
Keywords: antibacterial, mixed ligands, methionine, polypyridyl