Luminescent Heterobimetallic Pt-II-Au-I Complexes Bearing N-Heterocyclic Carbenes (NHCs) as Potent Anticancer Agents

This study aims to probe into new series of heterobimetallicPt(II)-Au-I complexes with a general formulaof[Pt(p-MeC6H4)(dfppy)(& mu;-dppm)Au(NHC)]OTf,NHC = IPr, 2; IMes, 3; dfppy = 2-(2,4-difluorophenyl)pyridinate;dppm = 1,1-bis(diphenylphosphino)methane, which are the resultantof the reaction between [Pt(p-MeC6H4)(dfppy)(& kappa;(1)-dppm)], 1, with[AuCl(NHC)], NHC = IPr, B; IMes, C, in thepresence of [Ag(OTf)]. In the heterobimetallic complexes, the dppmligand is settled between both metals as an unsymmetrical bridgingligand. Several techniques are employed to characterize the resultingcompounds. Moreover, the photophysical properties of the complexesare investigated by means of UV-vis and photoluminescence spectroscopy.Furthermore, the experimental study is enriched by ab initio calculations(density functional theory (DFT) and time-dependent DFT (TD-DFT))to assess the role of Pt and Au moieties in the observed optical properties.It is revealed that 1-3 is luminescentin the solid state and solution at different temperatures. In addition,the achieved results indicate the emissive properties of 1-3 are originated from a mixed (IL)-I-3/(MLCT)-M-3 excited state with major contribution of intraligandcharge transfer (dfppy). A comparative study is conducted into thecytotoxic activities of starting materials and 1-3 against different human cancer cell lines such as the pancreas(MIA-PaCa2), breast (MDA-MB-231), cervix (HeLa), and noncancerousbreast epithelial cell line (MCF-10A). The achieved results suggestthe heterobimetallic Pt-II-Au-I speciesas optimal compounds that signify the existence of cooperative andsynergistic effects in their structures. The complex 3 is considered as the most cytotoxic compound with the maximum selectivityindex in our screened complex series. Moreover, it is disclosed that 3 effectively causes cell death by inducing apoptosis in MIA-PaCa2 cells. Furthermore, the finding results by fluorescent cellmicroscopy manifest cytoplasmic staining of 3 ratherthan nucleus. Luminescent heterobimetallic Pt-II-(& mu;-P & BOTTOM;P)-Au-I-NHC derivativescan act as cooperative partners incancer therapy.

Automated summary

This study investigates a new series of heterobimetallic Pt(II)-Au(I) complexes and characterizes their photophysical properties. The complexes exhibit luminescent properties in both solid state and solution. The cytotoxic activities of the complexes are compared with starting materials against different human cancer cell lines, and the heterobimetallic Pt-II-Au-I species are found to be highly cytotoxic and capable of inducing apoptosis. The complex 3 is identified as the most cytotoxic compound with the highest selectivity index, and it effectively causes cell death through cytoplasmic staining.