Transition Metal Complexes Derived From 1H-Imidazole Ligand-Synthesis_Characterization_Cyclic Voltammetric Studies and In Vitro Antibacterial Evaluation

1*Waziri I., 1Fugu M. B., 2Zarma H. A., 3Isa B., and 1Askira N.K

1Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B. 1069, Maiduguri
2Department of Biochemistry, University of Maiduguri, P.M.B. 1069, Maiduguri
3Department of Chemistry, Borno state University, P.M.B. 1122, Maiduguri.

*Corresponding Author:


Metal complexes consist of metal ions chelated by a group of oppositely charged ions or neutral ligands. These compounds have various applications in stereochemistry, spectroscopy, catalysis, electrochemistry, agriculture, and the medical field; all play some significant roles. This work reports the complexes of Cr3+, Co2+, and Zn2+ metal ions derived from a 1H-imidazole ligand system. The complexes were characterized using EA, conductivity measurement, UV-Vis, FTIR, TGA, PXRD, HRMS, SEM-EDX, and 1H and 13C{H}NMR for the Zn2+ complex. Based on these characterizations, the ligand was found to act as a monodentate and formed a complex with the metal ions via a nitrogen atom. An octahedral geometry was obtained for Cr3+ and Co2+, with composition as Cr(IM)4(H2O)23 and [Co(IM)6]Cl2, and tetrahedral geometry for Zn2+ as [Zn(IM)2(H2O)2]. Redox conduct of the free chelate and the complexes was studied using cyclic voltammetry (CV). The result showed that Cr3+ and Co2+ compounds displayed a reductive wave of a one-electron irreversible system for Cr3+ to Cr2+ and Co2+ to Co+. The ligand shows a comparable electrochemical response to Cr3+ and Co2+ complexes with a reduction peak denoting a reduction involving one-electron transfer, while the Zn2+ complex shows neither oxidative nor reductive waves. The free ligand and the complexes were evaluated for antimicrobial activity against Gram-positive: (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative: (Escherichia coli and Klebsiella pneumoniae). From the result obtained, the complexes demonstrated enhanced activity compared to the ligand. The order of the activities among complexes on the organisms can be arranged as follows: Co2+ > Cr3+ > Zn2+.

Keywords and Phrases:

Transition metals.