Promising agent for the efficient extraction of Co(II) ions from aqueous medium and its metal complexes: Synthesis, theoretical calculations and solvent extraction

Abstract

A novel ligand 2,2′-((ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(4-((3-(4-methyl-1H-imidazol-1-yl)-5-(trifluoromethyl)phenyl)diazenyl)phenol) and its Co(II), Ni(II) and Cu(II), complexes were synthesized. These compounds were identified using elemental analysis, ICP-OES, FT-IR, thermal analysis, magnetic susceptibility, and molar conductivity techniques. 1H-, 13C-, and 19F-NMR spectra were used to describe the ligand further. 2,2′-((ethane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(4-((3-(4-methyl-1H-imidazol-1-yl)-5-(trifluoromethyl)phenyl)diazenyl)phenol) behaved as a bidentate, and the metal:ligand ratio of the complexes was 1:1, according to elemental analysis, stoichiometric analysis, and spectroscopic data on the synthesized molecules. Using DFT/B3LYP method and the 6-311G(d,p) basis set, the optimized molecular geometries, chemical shifts, vibrational frequencies, HOMO(SOMO)-LUMO energies, and molecular electrostatic potential diagrams of the synthesized compounds in the ground state were determined. In the calculations, the LANL2DZ basis set, which is the effective core potentials for Co(II), Ni(II) and Cu(II) ions, was used. When all of the theoretical data produced by quantum chemical calculations were compared to the experimental data, it was found that there was a good agreement between the two. Additionally, utilizing several transition metal picrates, including Mn(II), Pb(II), Cd(II), Zn(II), Ni(II), Co(II), Cu(II), Hg(II) and Fe(II) cations, the extraction capacity of the ligand was examined. The ligand demonstrated a significant rate of Co(II) cation removal from the aqueous medium in solvent extraction investigations, which also showed a great affinity for Co(II) ions.