Heteroleptic luminescent [Ir(C^N)2(N^N)]+ complexes containing 1-phenyl-1H-pyrazole or 1-(2,4-difluorophenyl)-1H-pyrazole as cyclometalating and α-diimines as ancillary ligands

Abstract

The synthesis of two series of novel cationic [Ir(C^N)2)(N^N)]+ complexes containing deprotonated 1-phenyl-1H-pyrazole or 1-(2,4-difluorophenyl)-1H-pyrazole (C^N) as cyclometalating and 1,10-phenanthroline derivatives (N^N) as ancillary ligands in the form of PF6– salts are reported. The synthetized complexes have been identified by means of 1H and 31P NMR spectroscopy. The complexes show very strong luminescence in acetonitrile solutions at room temperature and in CH3OH/C2H5OH 1:1 glasses at 77 K. Their luminescence properties, i.e., the emission spectra, quantum efficiencies and emission lifetimes, depend on the type of the cyclometalating and the α-diimine ligands coordinated and the measurement temperature. Depending on the α-diimine ligand the complexes exhibit the distinct changes in the nature of the emissive states.