Blue-green emissive cationic iridium(iii) complexes using partially saturated strongly-donating guanidyl-pyridine/-pyrazine ancillary ligands

Abstract

A new class of cationic iridium(III) complexes of the form [(C^∧N)₂Ir(N^∧N)][PF₆] is reported, where C^∧N = cyclometallating 2-phenylpyridinato, ppy, or 2-(2,4-difluorophenyl)-5′-methylpyridinato, dFMeppy, and N^∧N = guanidyl-pyridine, gpy, or -pyrazine, gpz, as the ancillary ligand. A large blue-shift in the emission coupled with a 7-to-9 fold enhancement in photoluminescence quantum yield and microsecond emission lifetimes were observed for the complexes containing the partially saturated gpy ligand as compared to the benchmark complex [(ppy)₂Ir(bpy)][PF₆], C1, where bpy is 2,2′-bipyridine.