Synthesis, characterisation and biological properties of gold(iii) compounds with modified bipyridine and bipyridylamine ligands

Square planar gold(iii) complexes that contain functionalised bipyridine ligands of general formula [Au(NN)Cl2][PF6] [where NN = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-dimethoxy-2,2'-bipyridine and 4,4'-diamino-2,2'-bipyridine] have been prepd. and characterised by NMR spectroscopy and mass spectrometry. Two of the complexes have also been characterised in the solid state by X-ray crystallog. In addn., a gold(iii) compd. bearing a dipyridin-2-ylamine ligand was also prepd. and characterised. The complexes were found to undergo hydrolysis under pseudo-physiol. conditions. Moreover, the complexes showed moderate to good cytotoxicity in vitro towards the A2780 human ovarian carcinoma cell line and the cisplatin resistant variant A2780cisR. Reactivity studies with biomols., such as reducing agents, plasmid DNA and a model protein (ubiquitin) were also performed to provide tentative insights into the mode of action of the complexes.