Synthesis, spectral characterization and X-ray crystallographic study of new copper(I) complexes. Antitumor activity in colon cancer

Three novel copper(I) complexes with three methyl 4-aryl-6-methyl-3,4-dihydropyrimidine-2(1H)-thione-5-carboxylate ligands were synthesized and fully characterized by elemental analysis, magnetic susceptibility, molar conductivity, ESI-MS, FTIR, UV–Vis and NMR. The difference between the three ligands is located in the aryl group: 4-(tert-butyl)phenyl (HL1), 2,6-dichlorophenyl (HL2) and 2,4-dichlorophenyl (HL3). Two ligands and complex 2 were characterized by single-crystal X-ray diffraction. The complex [CuCl(HL2)2]·dmso exhibits an almost perfect trigonal planar coordination geometry crystallizing in a space group P21/n, through the two sulfur atoms of the ligands, one chlorine atom bonded to the copper(I) and solvated with one molecule of dimethyl sulfoxide. The anticancer activity was evaluated in vitro against human colorectal cancer (CRC) cell line (Caco-2). The complexes have cytotoxic effect with IC50 values of 28.46, 25.03 and 38.83 μM respectively. Moreover, complexes 1 and 2 are able to strongly induce apoptosis in this CRC in vitro model.