Bioactive and luminescent indole and isatin based gold(i) derivatives.

A series of luminescent monometallic [AuL(PPh3)] (1-3) and bimetallic [Au2(µ-dppe)L2] (4, 6, 8) and [Au2(µ-dppp)L2] (5, 7, 9) complexes, where L is either 4-cyano-indole, isatin, or 5,7-dimethyl-isatin, and dppe and dppp are 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane, respectively, have been synthesised. X-ray diffraction confirmed the tendency to establish aurophillic interations for those complexes containing dppe. Luminescence studies and theoretical calculations revealed a different origin for both families, i.e. indole and isatin species. Thus, indole derivatives presented a ligand-to-ligand-charge-transfer transition (LLCT) from the indole to the PPh3 fragment, whereas for the isatin derivatives an intraligand-charge-transfer transition (ILCT) within the isatin fragment is proposed. In both cases, the gold centre was slightly implicated as a ligand-to-metal-charge transfer transition (LMCT) (from the indole/isatin to Au(i)). Cell antiproliferative assays in lung cancer cells (A549), leukemia Jurkat-pLVTHM and Jurkat-shBak cells (cisplatin sensitive and resistant, respectively) showed excellent cytotoxic values (10.11-0.28 µM), showing the leukemia cells to be the most sensitive and the bimetallic species to be the most active agents. Preliminary studies associated the cytotoxicity with a combination of different factors, the metallic fragment being mainly responsible. Remarkably, these complexes are able to inhibit the cellular growth of cisplatin resistant Jurkat-shBak cells highlighting their promising future as an alternative anticancer agent.

Structural and photophysical study on heterobimetallic complexes with d8-d10 interactions supported by carborane ligands: theoretical analysis of the emissive behaviour.

Heterobimetallic complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10 H10)M'(PPh3)] (M=Pd, Pt; M'=Au, Ag, Cu) and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] were obtained from the reaction of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (M=Pd, Pt) with [M'(PPh3)](+) (M'=Au, Ag, Cu) or by one-pot synthesis from [(SH2C2B10H10], (PPh2 )2C2B10H10, NiCl2 ⋅6 H2 O, and [Au(PPh3)](+). They display d(8)-d(10) intermetallic interactions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M=Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)-to-"P2-M-S2" (ML') charge-transfer (LML'CT) transitions for M=Pt and to metal (M)-to-"P2-M-S2" (ML') charge-transfer (MML'CT) transitions for M=Ni, Pd.