New Derivatives of Thiazolidine and Their Complexes with Cu2+ and Ag+: Synthesis, Theoretical Study, and Anti-Breast Cancer Activity

Abstract

Thiazolidine complexes have attracted interest due to their diverse coordination properties and biological activities. In this study, four new thiazolidine-4-carboxylic acid complexes (L1–L4) were synthesized by reacting L-cysteine with different aromatic and aliphatic aldehydes, followed by reaction with Cu(II) and Ag(I) ions in a 1:2 ratio. These complexes were extensively characterized by elemental analysis, FTIR, UV-vis, NMR, mass spectroscopy, magnetic susceptibility, molar conductivity, thermogravimetric analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). From spectroscopic analysis, it was revealed that all the complexes were bidentate NO-donor type, exhibiting square-planar or octahedral geometries around Cu(II) ion and tetrahedral geometries around Ag(I) ion. The cytotoxic activities of some complexes were evaluated against MCF-7 breast cancer cell lines. The results showed that all four ligands exhibited moderate cytotoxicity, whereas the Cu(L3)2 and Ag(L4)2 complexes showed greater cytotoxicity than their free ligands. DFT calculations were performed to confirm the study's results, which revealed that thiazolidine derivative complexes have greater potential to be developed into effective metal-based anticancer drugs.