Structural, Theoretical and Biological Studies on Cu2+ and Co2+ Complexes of New Thiosemicarbazone Ligands

Two sets of Cu2+, and Co2+ complexes of two 4 – Pyridyl thiosemicarbazone derivatives ligands symbolized by (H3L1), and (H3L2), were synthesized and examined utilizing different analytical, and spectroscopic techniques such as (FT-IR, Elemental Analysis, Magnetic studies, PXRD, UV-Vis, and GC-MS). Thermal stability along with kinetic parameters of both Co2+ complexes were studied. 1H NMR technique was used to confirm the structures of both ligands. The proposed geometries of complexes were recognized by density function theory (DFT) calculations using Material software. Additionally, Quantum theory of atoms in molecules (QTAIM) topological analyses for both ligands were obtained using Multiwfn software. The cyclic voltammogram revealed that copper ions are electroactive and exhibited two reduction waves. Fluorescence studies for both ligands showed a direct increase in the intensity of emissions because of increasing Co2+ concentration in solution. Moreover, several biological evaluations were carried out for all six compounds to evaluate their potential use as biological agents, including antioxidant activity using 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging approach, anti-microbial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans, DNA degradation activity, in addition to anticancer activity, along with molecular docking theoretical study against MCF-7 breast cancer cell line to determine the compounds ability to act as antitumor. It was found that the investigated compounds (especially the free ligands) have beneficial effects such as antimicrobial, antitumor, and DNA degradation agents. Furthermore, Co2+ complex (2) has the highest ABTS scavenging activity.