Blue and blue-green phosphorescent Au(iii) compounds based on a novel C^C chelate ligand framework are reported.

N-Heterocyclic carbene (NHC) cyclometalated gold(III) complexesr emainv ery scarce and therefore their photophysical properties remain currently underexplored. Moreover,g old(III) complexes emitting in the blue region of the electromagnetic spectrum are rare. In this work, as eries of four phosphorescent gold(III) complexes was investigated bearing four different NHC monocyclometalated( C^C*)-type ligands and ad ianionic (N^N)-type ancillary ligand ((N^N) = 5,5'-(propane-2,2-diyl)bis(3-(trifluoromethyl)-1 H-pyrazole) (mepzH 2 )). The complexes exhibit strongp hosphorescence when dopedi np oly(methyl methacrylate) (PMMA) at room temperature, which were systematically tuned from sky-blue [l PL = 456 nm, CIE coordinates:( 0.20, 034)] to green [l PL = 516 nm, CIE coordinates:( 0.31, 0.54)] by varying the monocyclometalated (C^C*)l igand framework. The complexes revealed high quantum efficiencies (f PL )o fu pt o4 3% and ex-cited-state lifetimes (t 0 )b etween 15-266 ms.The radiative rate constant values found for these complexes (k r = 10 3 -10 4 s À1 )a re the highest found in comparison to previously knownb est-performing monocyclometalated gold(III) complexes. Densityf unctional theory (DFT) and time-dependent DFT (TD-DFT) calculations of these complexes furtherl end support to the excited-state nature of these complexes. The calculations showed as ignificant contribution of the gold(III) metal center in the lowest unoccupied molecular orbitals (LUMOs) of up to 18 %, which wasf ound to be unique for this class of cyclometalated gold(III) complexes. Additionally, organic light-emitting diodes (OLEDs)w ere fabricatedb y using as olutionp rocess to provide the first insighti nto the electroluminescent (EL) properties of this new class of gold(III) complexes.

No abstract

N‐heterocyclic carbene (NHC) monocyclometalated gold(III) complexes: Highly efficient photoluminescence was achieved in the sky‐blue to green part of the electromagnetic spectrum using strong s‐donating cyclometalated NHC ligands and a dianionic (N N)‐type bidentate as the ancillary ligand. Detailed photophysical investigations supported by density functional theory calculations provide insights into the excited‐state properties of this new class of emitter molecules. The realization of the first solution‐processable OLED device based on these strongly luminescent gold(III) carbene emitter systems opens up exciting new opportunities in light emitting applications. More information can be found in the Full Paper by K. Venkatesan et al. on page 7265.