C^∧N‑Cyclometalated Platinum(II) Complexes with Sterically Demanding 1,2-Diarylimidazole Ligands

We describe the synthesis, characterization, and photophysical properties of 12 neutral cyclometalated platinum­(II) complexes with sterically demanding 1,2-diarylimidazole ligands and β-diketonate ancillary ligands. All complexes are photophysically active emitting in the blue-green to red region (490–590 nm) of the spectrum with quantum yields up to 58%, measured in poly­(methyl methacrylate) (PMMA) at room temperature. The steric demand of the imidazole ligand as well as of the β-diketonate ligand shows a significant effect on the quantum yield but not on the emission wavelength. These can be tuned by changing the substituents at the C-2 phenyl group of the imidazole ligand.