Effect of metal complex formation on the antibacterial activity of nitazoxanide: Spectroscopic and density functional theory calculations

In the present work, experimental and theoretical structural studies of two new nitazoxanide (NTZ) complexes, [Co(NTZ)(NO 3 ) 2 (OH 2 )] ( 1 ) and [Ni(NTZ)(CH 3 COO)(OH 2 )]·CH 3 COO ( 2 ) were reported. The susceptibility of Staphylococcus aureus and Escherichia coli towards NTZ and its complexes was assessed. NTZ behaves as a monodentate ligand via the thiazole N atom forming distorted octahedral and tetrahedral complexes with Co(II) and Ni(II) ions, respectively. The d‐d transitions were assigned by the aid of time‐dependent density functional theory calculations. The magnetic susceptibility value of 1 remains unchanged in the temperature range of 298–77K, while that of 2 decreases linearly with the temperature to attain 2.79 μ B at 77K. Coordination of NTZ (0.084 μmol ml −1 ) to Co(II) ( 1 ) (0.028 μmol ml −1 ) and Ni(II) ions ( 2 ) (0.079 μmol ml −1 ) leads to an improvement in the toxicity against S. aureus .