Towards blue emitting monocyclometalated gold(_III) complexes-synthesis, characterization and photophysical investigations

Blue emitting phosphorescent materials with high efficiency and high stability are a key requirement for the wider adoption of organic light emitting devices (OLEDs). In order to achieve triplet derived emission at the higher energy region of the electromagnetic spectrum, a series of neutral, monocyclometalated gold(_III) complexes with trifluoromethyl and trifluoromethoxy functionalized 2-phenylpyridine (ppy) derivatives, 2-anilinopyridine (apy), 2-benzoylpyridine (bpy) and 2-benzylpyridine (bepy), as the cyclometalating framework and diaryl or monoaryl alkyne as ancillary ligands have been designed and synthesized. Extensive photophysical and chemical characterization by various nuclear magnetic resonance spectroscopy techniques, elemental analysis and single crystal X-ray diffraction studies of selected compounds was carried out to confirm the structural and the chemical identity of the complexes. The emission wavelength maxima of the complexes appear in the blue/sky blue region of the electromagnetic spectrum. Detailed photophysical investigations revealed that the different emission properties of the complexes are predominantly dictated by the electronic properties of the cyclometalating ligand. The interesting photoluminescence properties along with the facile synthetic access makes this a promising concept to obtain highly suitable blue emitting gold(_III) complexes.