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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., A simple modification route of hydroxyl functionalized bis‐NHC dinuclear Au(I) complexes with anthracene is presented, which leads to a significant improvement of the antiproliferative activity and quantum yields up to 18%. By controlling the reaction parameters, one hydroxyl group remains, allowing for further potential bioconjugation to obtain a selective theranostic metal complex.

A series of histidine derived Au(I) bis‐NHC complexes bearing different ester, amide and carboxylic acid functionalities as well as wingtip substituents is synthesized and characterized. The stability in aqueous media, in vitro cytotoxicity in a set of cancer cell lines (MCF7, PC3 and A2780/A2780cisR) along with the cellular uptake are evaluated. Stability tests suggest hydrolysis of the ester within 8 h, which might lead to deactivation. Furthermore, the bis‐NHC system shows a sufficient stability against cysteine and the thiol containing peptide GSH. The benzyl ester and amide show the highest activity comparable to the benchmark compound cisplatin, with the ester only displaying a slightly lower cytotoxicity than the amide. A cellular uptake study revealed that the benzyl ester and the amide could have different intracellular distribution profiles but both complexes induce perturbations of the cellular physiological processes. The simple modifiability and high stability of the complexes provides a promising system for upcoming post modifications to enable targeted cancer therapy., Novel histidine‐derived Au(I) bis‐NHCs with different functional groups (ester, amide and carboxylic acid) show antiproliferative activity in MCF7, PC3 and A2780/A2780cisR cancer cell lines. A cellular uptake study revealed that the ester and the amide could have different intracellular distribution profiles but both complexes induce perturbations of the cellular physiological processes.

A novel N,N’‐allyl‐bridged bisimidazolium salt and a novel dinuclear Ag(I) and a Au(I) NHC complex are reported. Both metallacyclic complexes have a twisted structural shape due to the rigid allylic system and form two different isomers relating to the position of the double bonds. The allyl‐group shows photoisomerisation, but no reactivity towards bases for the additional coordination of Pd(II)., Building bridges: A novel N,N’‐allyl‐bridged bisimidazolium salt and a novel dinuclear Ag(I) and a Au(I) NHC complex are reported. Both metallacyclic complexes have a twisted structural shape due to the rigid allylic system and form two different isomers relating to the position of the double bonds. The allyl‐group shows photoisomerisation, but no reactivity towards bases for the additional coordination of Pd(II).