title: Dinuclear Au(i) N-heterocyclic carbene complexes derived from unsymmetrical azolium cyclophane salts: potential probes for live cell imaging applications.
abstract: We have synthesized a new series of azolium cyclophanes and used them as precursors of inherently luminescent dinuclear Au(i)-N-heterocyclic carbene (NHC) complexes. The azolium cyclophanes contained two azolium groups (either imidazolium or benzimidazolium), an o-xylyl group, and an alkyl linker chain (either C2, C3 or C4). All of the azolium cyclophanes were characterised by X-ray diffraction studies and VT NMR studies, and all were fluxional in solution on the NMR timescale. The C3- and C4-linked azolium cyclophanes served as precursors of Au2L2(2+) complexes (L is a cyclophane bis(NHC) ligand). Due to the unsymmetrical nature of the azolium cyclophanes, the Au2L2(2+) complexes each existed as cis and trans isomers. X-ray diffraction studies showed that the Au2L2(2+) complexes had short intramolecular AuAu distances, in the range 2.9-3.3 Å, suggestive of an aurophilic attraction, presumably as a consequence of the geometrical constraints imposed by the cyclophane bis(NHC) ligands. The complexes having the shortest AuAu distances (i.e., those based on C3-linked cyclophanes) exhibited intense luminescence in solution. The uptake of one of the dinuclear Au-NHC complexes by tumorigenic cells, and its subsequent distribution and toxicity in the cells, was monitored by luminescence microscopy over 6 h and proliferation measurements, respectively.
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Institute for Glycomics, Griffith University, Gold Coast Campus, QLD 4222, Australia. s.berners-price@griffith.edu.au.
authors.forename: Louise E
authors.initials: LE
authors.lastname: Wedlock
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC 3086, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barnard
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, WA 6009, Australia.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Filipovska
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Centre for Microscopy, Characterisation, and Analysis M310, The University of Western Australia, Perth, WA 6009, Australia.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Skelton
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Institute for Glycomics, Griffith University, Gold Coast Campus, QLD 4222, Australia. s.berners-price@griffith.edu.au.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Berners-Price
authors.affiliation: School of Chemistry and Biochemistry M310, The University of Western Australia, Perth, WA 6009, Australia. murray.baker@uwa.edu.au and Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 97401, Taiwan, ROC.
authors.forename: Murray V
authors.initials: MV
authors.lastname: Baker
mesh_terms: D001393:Azoles / Q000737:chemistry*; D045744:Cell Line, Tumor; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006046:Gold / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006801:Humans; D049449:Luminescence; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015335:Molecular Probes; D066244:Proton Magnetic Resonance Spectroscopy
chemical_list: D001393:Azoles; D056831:Coordination Complexes; D006571:Heterocyclic Compounds; D015335:Molecular Probes; C030011:carbene; D006046:Gold; D008697:Methane