Synthesis and characterization of new thiadiazole ligand and its Co(II), Ni(II), and Cu(II) complexes: Cyclic voltammetry (CV) and preliminary in vitro evaluation of the free ligand

The thiadiazole-based ligand (L1) and its Co(II), Ni(II), and Cu(II) complexes were synthesized and characterized using physicochemical methods, as well as supported by various spectroscopic techniques. FT-IR and UV–Visible spectroscopy, along with molar conductivity studies, supported the intended mode of coordination of ligands with metal ions and authenticated the proposed geometry of the complexes. Cyclic voltammetry studies were carried out to get an insight into the redox properties of the synthesized complexes. The redox couples were assigned, and reversibility of the reaction was assessed by calculating various electrochemical parameters like the ratio of anodic- to cathodic peak current (Ipa/Ipc) and peak potential difference (ΔEp). Results showed that the metal complexes displayed encouraging redox features, which are indicative of metal influence on the ligand electron attributes. Preliminary in vitro cytotoxicity screening of the free ligand L1 was performed against HBL-100 human breast epithelial cells and the MCF-7 breast cancer cells. Compound L1 did not reach 50% inhibition at the tested concentrations (15, 30, and 45 µg/mL); therefore, the IC₅₀ value was not determined under the experimental conditions.