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Among all the bio-metals, zinc and copper derivatives of ONS donor thiosemicarbazone have aroused great interest because of their potential biological applications. Multisubstituted thiosemicarbazone ligand H 2 dspt (3,5-dichlorosalicylaldehyde-N 4-phenylthiosemicarbazone) derived new ternary complexes like [Zn(dspt)(phen)]‧DMF (1) and [Cu(dspt)(phen)]‧DMF (2), and another thiosemicarbazone, H 2 dsct (3,5-dichlorosalicylaldehyde-N 4cyclohexylthiosemicarbazone), derived [Cu(dsct)(bipy)]‧DMF (3). These complexes have been characterized by elemental analysis (CHNS), Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) and proton nuclear magnetic resonance (1 H-NMR) spectra. The structures of the complexes were obtained by single-crystal X-ray diffraction analysis. Compounds 1 and 2 got crystallized in the monoclinic P2 1 /c space group. The complexes showed interesting supramolecular interaction, which in turn stabilizes the complexes. The ground state electronic configurations of the complexes were studied using the B3LYP/LANL2DZ basis set, and ESP plots of complexes were investigated. The interaction of the complexes with calf thymus DNA (CT-DNA) was studied using absorption and fluorescence spectroscopic methods. A UV study of the interaction of the complexes with calf thymus DNA (CT-DNA) has shown that the complexes can effectively bind to CT-DNA, and [Cu(dspt)(phen)]Á DMF (2) exhibited the highest binding constant to CT-DNA (K b = 3.7 × 10 4). Fluorescence spectral studies also indicated that Complex 2 binds relatively stronger with CT DNA through intercalative mode, exhibiting higher binding constant (K q = 4.7 × 10 5). The DNA cleavage result showed that the complexes are capable of cleaving the DNA without the help of any external agent. Molecular docking studies were carried out to understand the binding of complexes with the molecular target DNA. Complex 2 exhibited the highest cytotoxicity against human breast cancer cell line MD-MBA-231 (IC 50 = 23.93 μg/mL) as compared to Complex 1 (IC 50 = 44.40 μg/mL).

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A 3,5‐dichlorosalicylaldehyde‐N4‐cyclohexylthiosemicarbazone (C14H16Cl2N3OS) and its complexes [Zn(dsct)(phen)]·DMF (1), [Zn(dsct)(bipy)]·DMF (2), [Cu(dsct)(bipy)]·DMF (3) (phen = 1,10‐phenathroline, bipy = 2,2’bipyridine) were synthesized and characterized by CHN analysis, FT‐IR, UV–vis and NMR spectra. The molecular structure of the thiosemicarbazone (H2dsct) and its complexes have been resolved using single crystal XRD studies. In the complexes, thiosemicarbazone exist in the thioiminolate form and acts as dideprotonated tridentate ligand coordinating through phenolic oxygen, thioiminolate sulfur and azomethine nitrogen. The antibacterial activity of the prepared compounds were screened against Escherichia coli, Salmonella typhi, Enterobacter aerogenes, Shigella dysentriae, Bacillus cereus, Staphylococcus aureus. All the complexes showed activity against bacterial strains E.coli and Salmonella typhi. The thiosemicarbazone showed activity against three bacterial strains such as E. coli, Enterobacter aerogenes and Shigella dysentriae. Complex 2 showed very good antibacterial activity as compared to standard drug (Ampicillin) against the bacterial strain, Salmonella typhi. Finally, the thiosemicarbazone and its complexes have been used to accomplish molecular docking studies against an Epidermal Growth Factor Receptor (EGFR) and breast cancer mutant 3hb5‐oxidoreductase to determine the most preferred mode of interaction. The results confirm that the complex [Cu (dsct)(bipy)]·DMF(3) showed the highest docking score as compared to other complexes under study. The [Cu(dsct)(bipy)]·DMF(3) complex was evaluated for their anticancer activities against breast cancer cell line (MCF‐7) and normal L929 (Mouse Fibroblast) cell line. It was found that the compound showed an LC50 of 6.25 μg/mL against breast cancer cell line (MCF‐7).