Abstract
In the face of escalating bacterial resistance to
conventional antibiotics, the quest for novel antimicrobial strategies
is urgenter than ever. Metal complexes, particularly those with
biological activity, stand out as a promising alternative due to their
unique mechanisms of action and potential for fewer side effects in
comparison to standard organic antibiotics. This investigation
focuses on the synthesis and characterization of six Cu(II)
complexes, each formulated from halogen-substituted bidentate
Schiff base ligands. Employing a suite of analytical methods, Fourier
transform infrared, UV−vis, elemental analysis, and single-crystal
X-ray diffraction, the structures of the complexes were fully
established. All of the complexes were assigned to have square
planar geometry, with the ligand acting as a bidentate and
coordinate to the Cu(II) ion via nitrogen and oxygen atoms. The antibacterial efficacy of these complexes was rigorously tested
against both Gram-positive bacteria Staphylococcus aureus and Streptococcus pyogenes and Gram-negative bacteria Escherichia coli and
Klebsiella pneumoniae, utilizing the broth microdilution technique. The results revealed a spectrum of activity, with minimum
inhibitory concentrations (MICs) spanning from less than 15.63 to 125 μg/mL. Notably, Complex 2 demonstrated remarkable
potency against S. aureus and S. pyogenes, registering an MIC of less than 15.63 μg/mL. To elucidate the underlying mechanism of
action, molecular docking studies were performed targeting the topoisomerase IV receptor. The docking outcomes corroborated the
empirical data, underscoring the strong affinity of the complexes for the bacterial targets.