Blue-Emitting Dinuclear N-heterocyclic Dicarbene Gold(I) Complex Featuring a Nearly Unit Quantum Yield

Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au-2(RIm-Y-ImR)(2)](PF6)(2) (R = Me, Cy; Y = (CH2)(1-4), o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH2)(3) exhibit an intense blue emission (lambda(max) = 450 nm) with a high quantum yield (Phi(em) = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au center dot center dot center dot Au distance (3.272 angstrom). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au center dot center dot center dot Au distance