Ligand-driven variations in acylthiourea‑copper(I) complexes: Synthesis, characterization, and insights into anticancer efficacy

In this study, three acylthiourea ligands (HL1−HL3) were synthesized and used to prepare the corresponding Cu(I) complexes. The ligands and Cu(I) complexes were thoroughly characterized by spectroscopic and mass spectrometric methods, as well as single crystal X-ray diffraction (complexes 1 and 2), which revealed significant differences in their structures and nuclearities. Notably, the copper centres exhibited varied coordination environments depending on the ligand: complex 1 was a binuclear Cu(I)–Cu(I) species with a four-membered Cu₂S₂ core (featuring a direct Cu−Cu bond), whereas others (complexes 2 and 3) were mononuclear. DFT calculations for the prepared complexes were carried out, and the obtained data were consistent with the experimental data. All the complexes demonstrated significant cytotoxicity, with efficacy in the low micromolar range against human cancer cell lines (A549 lung, MCF-7 breast, and HepG-2 liver cancer cells) and notably exceeded the reference drug cisplatin in potency against certain cell lines . Biological studies (including staining and apoptosis assays, and cell cycle analyses) indicated that the complexes induced apoptotic cell death and cell cycle arrest in the MCF-7 cell line.