Platinum(II) Complexes with Phenylpyridine, Benzo[ h ]quinoline, and NHC Ligands: Exploration of Ligand Effects on Photophysical Properties

Platinum(II) complexes with one cyclometalated phenylpyridine or benzo[h]quinoline (C<^>N) ligand and an N-heterocyclic carbene (NHC) ligand are a robust and readily available class of sky-blue to green phosphorescent triplet emitters. They can be used as a benchmark system to investigate the influence of different ligands on the emissive properties of these [Pt(C<^>N)(NHC)I] complexes. This new class of com-pounds was fully characterized by standard techniques. Additionally a solid-state structure could be obtained. Photoluminescence measurements at room temperature revealed the strong emissive behavior of these compounds with quantum yields of up to 80%. The effect of electron-withdrawing and-donating groups on the photophysical proper-ties was examined and rationalized by density functional theory calculations (PBE0/6-311G(d)).