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The development of a potent metallodrug to prevent the progression of cancer is needed urgently. Here, three new complexes [Mn(pfth)2(o-phen)] (1), [Co(pfth)2(en)] (2) and [Ni(pfth)2(en)] (3) based on a 4-phenyl-(2-furoyl)-thiosemicarbazide (Hpfth) ligand containing 1,10 phenanthroline (o-phen)/ethylenediamine (en) as secondary ligands have been synthesized. The synthesized complexes have been characterized by various analytical, spectroscopic (IR, UV-vis., NMR), and single-crystal X-ray diffraction techniques. The results obtained by quantum chemical calculations (DFT and TD-DFT) agree with the experimentally observed values. The tumoricidal potential of Mn, Co, and Ni salts, ligand Hpfth, and their coordinate complexes was evaluated against K562, MCF-7, and DL cancer cell lines. Both short-term (XTT and MTT assays) and long-term (clonogenic assay) treatment of the tumor cells studied through colorimetric, clonogenic, and fluorescence-based assays by the complexes demonstrated true anti-tumor effects against these cancer cells. The results suggest the significant antitumor potential of the metal–ligand complexes against the tumor cells in a dose-dependent manner with higher growth inhibition, apoptosis, and inhibition in colony formation in comparison to either metal salts or free ligands. Complexes 1 and 3 induce more growth inhibition as compared to complex 2 against all cancer cell lines. Complex 3 demonstrated impressive tumoricidal properties in a clonogenic assay in comparison to complexes 1 and 2. These studies establish the role of metal centers in antiproliferative activities and reveal that Ni(II) exhibits more potent anti-tumoricidal activity. Molecular docking studies of Hpfth and complexes 1–3 were also performed against three target proteins 6NE5: Myeloid Cell Leukemia-1 (Mcl-1), 6E91: Carbonic anhydrase IX (CA IX), and 6H0W: Lysine Demethylase 4D and the results displayed favorable binding interactions. [ABSTRACT FROM AUTHOR]

The electrochemical water splitting by transition metal complexes is emerging very rapidly. The nickel complexes also play a very vital role in various biological activities. Here, three new ligands {H2mbhce = N′-(4-methyl-benzoyl), H2pchce = N′-(pyridine-carbonyl) and H2hbhce = N′-(2-hydroxy-benzoyl) hydrazine carbodithioic acid ethyl ester} and their corresponding Ni(II) complexes [Ni(Hmbhce)2(py)2] (1), [Ni(pchce)(o-phen)2]·CH3OH·H2O (2) and [Ni(hbhce)(o-phen)2]·1.75CHCl3·H2O (3) have been synthesized and fully characterized by various physicochemical and X-ray crystallography techniques. The photoluminescence study and thermal degradations were also examined. The treatment of K562 cells with the increasing concentrations of the nickel salts, ligands, and complexes 1, 2, and 3 showed dose-dependent cytotoxicity. The cytotoxic activity of ligands reveals that ligand H2mbhce is more potent in inhibiting the growth of tumor cells in comparison to other ligands H2pbhce and H2hbhce. Cytotoxicity assay results indicate that all complexes have remarkable cytotoxic potential in comparison to either nickel salts or the free ligands. Among these complexes, complex 1 has significantly better anti-tumor activity as compared to complexes 2 and 3. The electrochemical study of complexes 1, 2, and 3 for water oxidation reveals that all the complexes possess admirable electrocatalytic activity towards oxygen evolution reaction (OER) and have lower overpotential (328, 338, and 370 mV, respectively) than many previously reported complexes and RuO2 (390 mV). Among complexes 1, 2, and 3, complex-2 shows a better water oxidation response. Consequently, these complexes have great potential to be utilized in fuel cells. The more reliable electrochemical parameter TOF is also calculated for all three complexes. [ABSTRACT FROM AUTHOR]