Exploiting click-chemistry: backbone post-functionalisation of homoleptic gold(i) 1,2,3-triazole-5-ylidene complexes

The synthesis of a homoleptic azide-functionalised Au(i) bis-1,2,3-triazole-5-ylidene complex is reported, starting from a backbone-modified 1,2,3-triazolium salt ligand precursor. The incorporated azide handle allows for a straightforward modification of the complex according to click-chemistry protocols without impacting the steric shielding around the metal center, demonstrating the superiority of the presented triazole ligand framework over imidazole based systems. Employing the SPAAC and the CuAAC reactions, post-modification of the complex is facilitated with two model substrates, while retaining very high antiproliferative activity (nanomolar range IC₅₀ values) in A2780 and MCF-7 human cancer cells.