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Metal(II) Complexes of Mixed Ligands Trimethoprim and 2,2' Bipyridine Heterocycle: Synthesis,
Characterisation and Antimicrobial Studies
Tunmise T. Eugene-Osoikhia.,1* Sodeeq A. Ojeyemi.,1 Raymond A. Akong.,1
Temidayo Oyetunde.,2 Emmanuel U. Onche3 and Funmilola Ayeni4
1Department of Chemistry, University of Ibadan, Ibadan, Nigeria
2Department of Chemical Sciences, Redeemer’s University, Ede, Nigeria
3School of Chemistry, University of Manchester, Manchester, United Kingdom
4Department of Pharmaceutical Microbiology, University of Ibadan, Ibadan, Nigeria
* Corresponding Author: kemitunmise@yahoo.co.uk
Abstract
Metal (II) complexes of mixed-ligand trimethoprim (TMP) and 2,2′-bipyridine (bipy) with
the formular [M(TMP)(bipy)X].nH2O, where M = Mn(II), Co(II), Ni(II), Cu(II), Fe(II),
Zn(II) and X= Cl/SO4, were synthesized and characterized by percentage metal, infrared,
electronic spectroscopies, room temperature magnetic moments, melting points,
conductance measurements and elemental analysis. The infrared spectral data showed TMP
as a bidentate ligand bonding to the metals via the N atom of the pyrimidine amino group
(3412-3300 cm-1) and nitrogen atom of the azomethine moiety (1666-1639 cm-1) while the
bipy bonded through the diimine nitrogen atoms (1593-1404 cm-1). The electronic spectral
data and magnetic moments indicated that the metal (II) complexes have octahedral
geometries and were monomeric. The molar conductance of the complexes in the range 24-
40 Ω-1cm2 mol-1 confirmed their non-electrolytic and covalent nature. The antimicrobial
studies showed that the complexes were inactive towards the tested fungus Candida
albicans, but possessed good antibacterial activities. The observed trend for the antibacterial
activities displayed by the complexes was in the order Mn >Zn > Cu > Fe > Co ~ Ni thus
making [Mn(TMP)(bipy)Cl2].2H2O the most biologically active among them. It was also
observed that antibacterial activities exhibited varied directly with concentration as the
highest activities were observed at the highest concentration of 40 mg/mL.
Keywords: Trimethoprim, 2,2'-bipyridine, Mixed- ligands, Antimicrobial, Metal Complexes,
Heterocycle.