The design of organometallic compounds with efficient phosphorescence in the deep red to near-infrared portions of the spectrum is a long-standing fundamental challenge. Here we describe a series of heteroleptic bis-cyclometalated iridium complexes with phosphorescence in these low-energy regions of the spectrum. The cyclometalating ligands in this study feature a metalated benzothiophene aryl group substituted with a quinoline, isoquinoline, or phenanthridine heterocycle. Increasing the conjugation on the heterocycle stabilizes the ligand-centered LUMO, decreases the HOMO−LUMO gap, and enables phosphorescence to occur at long wavelengths. These cyclometalating ligands are paired with a variety of electron-rich ancillary ligands, such as dithiocarbamate (dipdtc), β-ketoiminate (acNac), β-diketiminate (NacNac), amidinate (dipba), and hexahydropyrimidopyrimidine (hpp), some of which have significant influences on the phosphorescence wavelength and excited-state dynamics. The syntheses of seven compounds in this series are described, three of which are structurally validated by single-crystal X-ray diffraction. Cyclic voltammetry reveals the effects of ligand modification on the frontier orbital energies. The photophysical properties of all compounds are thoroughly characterized by UV−vis absorption spectroscopy and steady-state photoluminescence at room-temperature and 77 K. Photoluminescence quantum yields and lifetimes of all compounds are reported.

A procedure was developed for the synthesis of fluorinated 2-aminopyridines based on the reactions of 1,1-enediamines, benzaldehydes and 1,3-dicarbonyl compounds.

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