Structure–property relationship studies of copper(I) complexes of nanosized hypodentate ligands and evaluation of their antitumor and antimicrobial activities

We report the preparation of four nanosized isomers of N-benzoyl-N′-(hydroxyphenyl) thioureas by nanoprecipitation. Direct reactions with CuCl₂·2H₂O gave the corresponding complexes in good yields. The structures of the ligands and their copper complexes were characterized using different analytical and spectroscopic measurements. In all complexes, the data revealed non-electrolytic mononuclear three-coordinate copper(I) complexes, where the ligand is hypodentate to copper ion via thioamide sulfur. Thermal studies revealed high thermal stability of the complexes compared to their parent ligands and the mechanism of decomposition and the thermodynamic parameters were evaluated. The ligands and their complexes were screened against different pathogenic microorganisms, and subjected to in vitro antioxidant and cytotoxic activities against three human cell lines. Compared to other isomers, N-benzoyl-N′-(o-hydroxyphenyl) thiourea exhibited significant antimicrobial activity and had higher activity than the standard fungicides and bacteriocides. All copper complexes showed inhibitory potencies, however [Cu(H₂L²)₂Cl] exhibited remarkable inhibitory activities against the examined cancer cell lines as evident by the range of IC₅₀ values (4.0–7.4 μg/mL) and the percentage of cell viability. The results obtained can find medical applications as new therapeutic nanoparticle agents.