Stable N-heterocyclic carbene (NHC) cyclometalated (C^C) gold(iii) complexes as blue–blue green phosphorescence emitters

Abstract

Blue and blue-green phosphorescent Au(III) compounds based on a novel C^C chelate ligand framework are reported. The influence of the three different cyclometalated NHC ligands as well as the different ancillary ligands on phosphorescence emission energies and quantum efficiencies is evaluated. The complexes exhibit different emission behavior in solution, at 77 K and when doped in thin films of polymethyl methacrylate (PMMA) depending on the nature of the NHC ligands. A combination of the unique electronic structure of the Au(III) complexes with the NHC ligand as part of the cyclometalating ligand framework and significantly enhanced emission properties of the complexes at higher energy could make these class of molecules highly interesting for applications in OLEDs and catalysis.