Iron(II) and cobalt(II) Complexes of 3,4-Dihydroxybenzaldehyde-4-ethylthiosemicarbazone: Synthesis, Spectral Studies and Molecular Docking

Fe(II) and Co(II) complexes of 3,4-dihydroxybenzaldehyde 4-ethylthiosemicarbazone were synthesized and characterized by elemental analysis (CHNS), magnetic susceptibility measurements, molar conductivity, Fourier transform infrared (FT-IR), nuclear-magnetic resonance (¹H-NMR and ¹³C-NMR) and ultraviolet-visible (UV-Vis) spectra. The spectral and analytical data revealed that the obtained thiosemicarbazone-metal complexes have tetrahedral geometry around the metal center. The studied ligand acts as a bidentate ligand by using both azomethine nitrogen and thiol sulphur as monoanion center of donation. To predict the reactive sites for electrophilic and nucleophilic attack, the Molecular Electrostatic Potential (MEP) was determined. The antibacterial activities of 3,4-dihydroxybenzaldehyde 4-ethylthiosemicarbazone ligand and its complexes were tested by molecular docking technique into the crystal structure of topoisomerase II and topoisomerase IV proteins. Molecular docking investigation proved that, the ligand and its complexes had interesting interactions with active sites of amino acids of the target proteins. The Co(II) complex exhibited better potential inhibition than other studied compounds.