Tailoring, spectroscopic, DFT, solvatochromic, antitumor, and molecular docking studies of new polynuclear Cu(II)-hydrazone complexes

Hydrazones and their metal complexes have acquired a lot of interest because of their various biological and catalytic applications. The reaction of the symmetrical hydrazone (NBHD) with Cu(II) salts, including Cl^-, Br^-, and SO₄^2-, has been investigated. The structures of Cu-NBHD complexes were explored by using various spectroscopic and analytical tools. Fluorescence spectra for NBHD and Cu(II)-NBHD complexes were recorded in a large number of solvents to probe their solvatochromic manners. Theoretical calculations for NBHD and Cu-NBHD complexes were conducted, and the results were correlated with the experimental data. The anticancer action of Cu-NBHD complexes was investigated towards Hepatocellular carcinoma and the results were supported by molecular docking studies. The Cu-NBHD complexes have distorted octahedral geometrical structures as evidenced from magnetic moment, electronic and ESR spectral data. NBHD acts as a bis(monoanionic bidentate) in case of Cl^- and Br^- ions and bis(neutral bidentate) in case of SO₄^2- ion. The coordinating sites are phenolic oxygen and azomethine nitrogen atoms. In case of bromo and sulfato complexes, binuclear complexes were obtained. However, a tetranuclear complex was obtained in case of the chloro complex. DFT calculations for NBHD and Cu-NBHD complexes were performed, and the results were correlated with the practical results. All Cu-NBHD complexes exhibited anticancer activity towards Hepatocellular carcinoma. The bromo complex 2 showed an enhanced activity than that of cisPt. Using different copper(II) salts gives different bi- and tetra-nuclear complexes. Al complexes exhibited anticancer activity towards Hepatocellular carcinoma and the bromo complex 2 showed enhanced activity than that of cisPt. The encouraging activity prompts further studies about the complex as an antitumor agent.