Synthesis, X-ray structure, DFT calculations and anticancer activity of a selenourea coordinated gold(I)-carbene complex

A gold(I)-carbene complex, [Au(IPr)(Seu)]PF₆ (1), where Seu = Selenourea and IPr = 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-ylidene, was prepared using [Au(IPr)Cl] and characterized by elemental analysis, IR, and NMR (¹H, ¹³C, ⁷⁷Se) methods. The crystal structure of 1 was determined by single-crystal X-ray diffraction analysis, which shows that the complex (1) adopts a linear geometry about gold(I). The structures of the [Au(IPr)(Seu)]PF₆ monomer as a model of 1 and that of the dimer, {[Au(IPr)(Seu)]PF₆}₂ were optimized at the B3LYP-D3 level of theory. The DFT results give support to the experimentally determined monomeric structure. The in vitro cytotoxic activity of [Au(IPr)Cl] and complex 1 was investigated against three human cancer cell lines; A549(lung carcinoma), HCT15(colon cancer) and MCF7(breast cancer). The IC₅₀ values showed that the selenourea-containing complex (1) was less potent than cisplatin in inhibiting the growth of cancer cells. The stability of complex 1 in phosphate buffered aqueous solution and its interaction with amino acids; glutathione and L-cysteine were studied using square wave stripping voltammetry.