Synthesis, Spectroscopic Characterization, DFT Calculations, and Molecular Docking of Novel Thiourea Complexes and Their Cytotoxic and Antimicrobial Activities

Abstract

This research presents the synthesis and comprehensive characterization of two novel bioactive thiourea derivatives (TU¹ and TU²) and their complexes with Pd(II), Cd(II), Cu(II), and Ni(II) salts. The ligands effectively formed stable chelates with the metal ions, displaying specific 1:1 and 1:2 stoichiometric ratios. Reduction of Cu(II) by thiourea was approved by the diamagnetic behavior of the yielded Cu(I)-TU complexes. Thermal analysis indicated that the complexes possess significant thermal stability. Computational studies provided detailed insights into the electronic properties, such as energy gaps and dipole moments, which correlate with the observed chemical reactivity and the cell membrane permeability to the complexes. Notably, the Cd(II)-TU² complex demonstrated significant in vitro anticancer activity with IC₅₀ values of 17.8 ± 0.6 μM and 12.0 ± 0.3 μM against MCF-7 and HepG-2 cell lines, respectively. This complex displayed slightly superior activity compared to cisplatin and nearly threefold the efficacy of imatinib. The superior activity of Cd(II)-TU² complex could be due to the existence of many electron-rich sites in the 1,4-benzodioxane moiety and less bulky acetamide substituent of TU² ligand. The data suggest that the synthesized compounds, especially the Cd(II)-TU² complex and the TU² ligand, are promising candidates for further investigation in therapeutic applications, particularly in the development of anticancer agents.