Maoliang Xu, R. Zhou, Geyang Wang
May 15, 2009
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0
Influential Citations
22
Citations
Journal
Inorganica Chimica Acta
Abstract
Abstract A series blue phosphorescent emitting materials based on 2-(fluoro substituted phenyl)-4-methylpyridine as the cyclometalated ligands have been synthesized and characterized. The complexes have the general structure (C ^ N) 2 Ir(pic), where C ^ N is a monoanionic cyclometalating ligand (e.g., 2-(2,4-difluorophenyl)-4-methylpyridine (24f 2 pmpyH), 2-(3,4-difluorophenyl)-4-methylpyridine (34f 2 pmpyH), 2-(3,5-difluorophenyl)-4-methylpyridine (35f 2 pmpyH), and 2-(3,4,5-trifluorophenyl)-4-methyl-pyridine (345f 3 pmpyH)), pic is 2-picolinic acid. The absorption, emission, cyclic voltammetry and thermostability of the complexes were systematically investigated. The (46f 2 pmpy) 2 Ir(pic) has been characterized using X-ray crystallography and the electronic ground state calculated using B3LYP density functional theory. HOMO levels are a mixture of Ir and 2-(fluoro phenyl)-4-methylpyridine ligand orbitals, while the LUMO is predominantly pic ligand based. Introduction of fluorine atoms and methyl group into ppy ligand and changing in position of F substituents in phenyl ring can finely tune emission of the complexes, showing bright blue-to-green luminescence at a wavelength of 463–501 nm at room temperature in CH 2 Cl 2 .