The reaction of gold nanoparticles with benzimididazol-2-ylidene ligands leads to the formation of well-defined bis-carbene gold(I) complexes, as shown by characterization techniques such as powder XRD and solid state NMR.

The synthesis, structural characterization and the study of the photophysical properties of complexes [AuCu(C₆F₅)₂(NC–CH₃)₂] 1, [AuCu(C₆F₅)₂(NC–Ph)₂]₂2, and [AuCu(C₆F₅)₂(NC–CHCH–Ph)₂] 3 have been carried out. The crystal structures of complexes 1–3 consist of dinuclear Au–Cu units built from mediated metallophilic Au(I)⋯Cu(I) interactions. In the case of complex 2 two dinuclear units interact via an aurophilic interaction leading to a tetranuclear Cu–Au–Au–Cu arrangement. Complex 2 is brightly luminescent in solid state at room temperature and at 77 K with a lifetime in the nanoseconds range, while complexes 1 and 3 do not display luminescence under the same conditions. The presence of the aurophilic interaction in complex 2 seems to be responsible for the blue luminescence observed. DFT and time-dependent DFT calculations agree with the experimental results and support the idea that the origin of the luminescence of these complexes arise from orbitals located in the interacting metals.

Monodisperse Au–Ag alloy nanoparticles of different compositions are prepared through the mild decomposition of the bimetallic precursor [Au₂Ag₂(C₆F₅)₄(OEt₂)₂]_n in an organic solvent using hexadecylamine (HDA) as a stabilizing ligand. The effects of different reaction parameters on the size and composition of the nanoparticles, such as the metal : HDA ratio, the use of H₂ reducing gas or the solvent (toluene, THF or mesitylene), have been studied through TEM, HRTEM, EDS, UV/Vis and ¹⁹F NMR spectroscopy. The localized surface plasmon resonance (LSPR) displayed by the spherical Au–Ag nanoparticles can be tuned as a function of the metal composition.