Design and Characterization of Ni(II) and Cu(II) Complexes With Methionine and 1,10-Phenanthroline: Antibacterial and Anti-Fungal Properties

This research focused on the design and characterization of two new transition metal complexes, NiMetPhe and CuMetPhe, derived from methionine (Met) and 1,10-phenanthroline (Phe), coordinated with Ni(II) and Cu(II) ions, respectively. Structural elucidation through analytical techniques, conductivity, elemental analysis, FTIR spectra, electronic spectra, magnetic moment, mass spectra, and thermal degradation, confirmed their octahedral geometries with the formulas [Ni(Met)(Phe)(Cl)(H2O)] and [Cu(Met)(Phe)(Cl)(H2O)]. Thermal analysis revealed their stability and decomposition patterns, whereas density functional theory (DFT) calculations validated the structures and provided insights into quantum chemical parameters, such as highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energies, molecular orbitals, and electronic distributions. In vitro antibacterial and anti-fungal assays showed significantly enhanced bioactivity for both complexes compared to the free ligands, indicating that metal coordination boosts biological efficacy. Molecular docking studies targeting the Escherichia coli FabH-CoA complex (PDB ID: 1HNJ), a key enzyme in fatty acid biosynthesis, revealed strong binding affinities, interaction energies, and involvement of critical amino acid residues. These findings highlight NiMetPhe and CuMetPhe as promising candidates for antimicrobial therapies, particularly against resistant strains, underscoring their potential for future medical applications.