Complexes of Co and Cu with SMZ were successfully synthesized (1:2 molar ratio) in good yield and characterized by using UV-vis, FTIR, melting point/decomposition temperature, electrical conductivity and solubility in different solvents of varying polarity and proticity. All the prepared complexes were coloured. From the IR results, 529, 631, 528 and 779 cm-1 bands were observed in the spectra of the complexes which were absent in the free ligand spectrum thus, showing the presence of metal-ligand bond (coordination) in the complexes. The electronic spectral data of the complexes suggest an octahedral and tetrahedral geometry for all the complexes. The ligand and the Co (II) complex were found to be soluble polar protic solvents at both room and elevated temperature while, Cu (II) complex was found to be insoluble in polar protic solvent (ethanol) at room temperature but soluble at elevated temperature. The metal complexes are insoluble in non-polar solvent at both temperatures. More so, the ligand was found to be soluble in non-polar solvent at both temperatures. The electrical conductivity measurements indicated that the synthesized complexes are non-electrolytes. The synthesized metal complexes showed improved broad-spectrum antimicrobial activity against E. coli and S. aureus as compared to the ligand.  Thus, the complexes [Co(C10H11N3O3S)] and [Cu(C10H11N3O3S)] are good leads to be developed into antibiotics against the tested antimicrobial agents (E. coli and S. aureus).

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The complexes of Co and Cu with sulfamethoxazole (SMZ) were synthesized in the 1:2 molar ratios. The physical characterization of the ligand and the complexes showed different colours with a good % yield and high melting point/decomposition temperature. The solubility test of the metal complexes and the free drug using various solvents of different polarity and proticity showed that the free drug and the metal complexes are soluble in polar and non-polar solvents. The IR results of the synthesized complexes displayed new peaks that are not present in the free drug, the bands are due to M-O and M-N thus, confirming the coordination. The result from the conductivity measurement shows that the complexes are non-electrolyte. More so, all the complexes were found to be toxic in brine shrimp lethality assay.