Cr(III) and Ni(II) Complexes of Isatin-hydrazone Ligand: Preparation, Characterization, Dft Studies, Biological Activity, and Ion-Flotation Separation of Ni(II)

Abstract

Abstract In the current work, a ligand N'1-((E)-2-hydroxy-3H-indol-3-ylidene)-N'3-((E)-2-oxoindolin-3-ylidene)malonohydrazide (H4MDI) and its Cr(III) and Ni(II) complexes have been synthesized and characterized by various conventional methods. For evaluating the optimal ligand structure and its complexes, calculations of DFT were applied. Magnetic measurements inherent to their electronic spectra show that both Cr(III) and Ni(II) chelates have octahedron coordination frameworks. On the other hand, the IR spectral data revealed that the ligand behaves as a binegtive hexadentate in [Cr2(H2MDI)(H2O)2Cl4] and as a tetranegative hexadentate in [Ni2(MDI)(H2O)6].4H2O. In addition, the behavior of thermal decomposition for prepared complexes was discussed. Two comparable methods (Coats-Redfern and Horowitz-Metzger) were used to calculate the kinetic parameters of the resulted thermal decomposition stages. Furthermore, the ion-flotation process was used for the separation of Ni(II) from aqueous media via the prepared ligand as a chelating agent and oleic acid as a surfactant. Moreover, the antimicrobial behavior of the synthesized moieties was investigated against various bacterial and fungal strains. H4MDI has the most activity with minimum inhibitory concentration (MIC) of 0.78 µg/mL for both E. coli, and C. Albicans, while Ni(II) complex shows the activity against S. aureus, E. coli, and C. Albicans with MIC of 2.34, 4.68, and 1.17 µg/mL, respectively. Finally, the in-vitro cytotoxic activity of the prepared compounds against hepatocellular carcinoma human tumor cells (HePG-2) has been examined, and revealed that H4MDI and its Ni(II) complex show very strong activity against HePG-2 with IC50 of 9.7 and 7.7 µmol/L, respectively.