Blue phosphorescent nitrile containing C^C cyclometalated NHC platinum(ii) complexesElectronic supplementary information (ESI) available: Details of the photophysical measurements and solid-state structures, 2D NMR spectra as well as Cartesian coordinates for the optimized structures. CCDC 972158-972160. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3dt53264j

Since C^C* cyclometalated Pt( ii ) complexes with N-heterocyclic carbene (NHC) ligands have been identified as potential emitter materials in organic light-emitting devices (OLEDs), very promising results regarding quantum yields, colour and stability have been presented. Herein, we report on four nitrile substituted complexes with a chelating NHC ligand (1-(4-cyanophenyl)-3-isopropyl-1 H -benzo[ d ]imidazole or 4-( tert -butyl)-1-(4-cyanophenyl)-3-methyl-1 H -imidazole) and a bidentate monoanionic auxiliary ligand (acetylacetone or dimesitoylmethane). The complexes have been fully characterized including extensive 2D NMR studies (COSY, HSQC, HMBC, NOESY, 195 Pt NMR), three of them also by solid-state structures. Photophysical measurements in amorphous PMMA films and pure emitter films at room temperature reveal the impact of the mesityl groups in the auxiliary ligand, which led to a significant increase of the quantum yield, while the decay lifetimes decreased. The electron withdrawing nitrile groups shift the emission towards blue colour coordinates. On the influence of nitrile substituents towards the emission properties of C^C* cyclometalated platinum( ii ) complexes with N-heterocyclic carbene ligands.