Preparation, characterization, single-crystal analysis, and cytotoxic assessment of complexes formed by Schiff base and 8-hydroxyquinoline co-ligand with Co(II), Ni(II), and Mn(II) metal ions

By combining 2-((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L1) and 8-hydroxyquinoline (L2), mixed ligand complexes of Ni(II), Co(II), and Mn(II) were synthesized. L1’s crystal structure was established via single crystal X-ray. Lastly, the MTT assay assessed mixed-ligand complex toxicity to human lung cancer and bronchial epithelial cell lines (A549 and BEAS-2B). [Display omitted] This study focuses on the preparation of mixed ligand complexes of Ni(II), Co(II), and Mn(II) by combining the co-ligands 2-(((4-fluorophenyl)imino)methyl)-4-methoxy-6-nitrophenol (L1) and 8-hydroxyquinoline (L2). The chemical structures of the all compounds were examined using various techniques, including 1H and 13C NMR, FT-IR, UV–Vis, TGA, molar conductivity, LC-MS/MS, elemental analysis and magnetic susceptibility. The crystal structure of the ligand L1 was determined using single crystal X-ray analysis revealing that the ligand favors the phenol-imine tautomeric form in the solid state. All complexes are suggested to have an octahedral structure. Finally, the MTT assay was used to determine the toxicity level of the mixed ligand complexes in human non-small cell lung cancer (A549) and normal bronchial epithelial cell lines (BEAS-2B). The results showed that the [Ni(L1)(L2).(H2O)2] complex (IC50: 5.97 µM) exhibited high cytotoxic activity at a lower dose than cisplatin compared to the other compounds. In contrast, the [Ni(L1)(L2).(H2O)2] complex was shown to exhibit significantly lower cytotoxic activity (IC50 > 100 s µM) in the BEAS-2B (normal bronchial epithelial cell) cell line. The other compounds [Co(L1)(L2).(H2O)2] and [Mn(L1)(L2).(H2O)2] were shown to have no significant anticancer activity in A549 cells due to their cytotoxic activity at higher doses than cisplatin (IC50 > 100 s µM).