Improved Antiproliferative Activity and Fluorescence of a Dinuclear Gold(I) Bisimidazolylidene Complex via Anthracene-Modification

A straightforward modification route to obtain mono- and di-substituted anthroyl ester bridge functionalized dinuclear Au(I) bis-N-heterocyclic carbene complexes is presented. The functionalization can be achieved starting from a hydroxyl-functionalized ligand precursor followed by transmetallation of the corresponding Ag complex or via esterification of the hydroxyl-functionalized gold complex. The compounds are characterized by NMR-spectroscopy, ESI-MS, elemental analysis and SC-XRD. The mono-ester Au complex shows quantum yields around 18%. In contrast, the corresponding syn-di-ester Au complex, exhibits significantly lower quantum yields of around 8%. Due to insufficient water solubility of the di-ester, only the mono-ester complex has been tested regarding its antiproliferative activity against HeLa- (cervix) and MCF-7- (breast) cancer cell lines and a healthy fibroblast cell line (V79). IC₅₀ values of 7.26 μM in the HeLa cell line and 7.92 μM in the MCF-7 cell line along with selectivity indices of 8.8 (HeLa) and 8.0 (MCF-7) are obtained. These selectivity indices are significantly higher than those obtained for the reference drugs cisplatin or auranofin.