Iridium complex phenylpyridine

The first iridium complex used in PHOLED devices was fac tris(2-phenylpyridine) iridium Ir(ppy)3 complex [282]. It has a short triplet lifetime ( 1 ps) and high phosphorescent efficiency (p = 40% at room temperature in solution) [283]. However, in the solid state, most iridium complexes showed very low phosphorescent QE due to aggregate quenching. In most cases, the complexes have to be diluted in host materials to avoid reducing the... 

Another efficient material introduced by the same group is the green emitting /ac-tris(2-phenylpyridine)iridium [Ir(ppy)3, 67] [38], A suitable host for this phosphorescent emitter is CBP (10). The triplet lifetime is rather short, the experimentally determined value being 500 ns in the CBP matrix. Another iridium complex was shown to emit in the red with high efficiency due to the short phosphorescence lifetime in comparison with PtOEP [165]. 

Three iridium complexes of formula [Ir(acac)(L)2] have been synthesized, [k(dpp)2 (acac)], [Ir(bpp)2(acac)j and [Ir(fpp)2(acac)j, where L is a substituted arylpyridine (dpp = 2,4-diphenylpyridine bpp = 2-(4-f-butylphenyl)-4-phenylpyridine fpp = 2-(4-fluoroph-enyl)-4-phenylpyridine). The OLEDs based on these materials, with structure ito/Ir com-plexipvk/F-tbb/Alqs/LiF/Al (F-tbb = l,3,5-tris(4-fiuorobiphenyl-4 -yl)benzene), showed maximum luminances of 8776, 8838 and 14180 cdm , and maximum external efficiencies of 11.5, 12.9 and 17.0 cdA, repectively ° . 

Polystyrenes have also been used to support chromophores useful in organic light-emitting diodes (OLEDs). Week and coworkers have attached tris(2-phenylpyridine) iridium complexes to aminomethylated polystyrene using a Schiff base reaction, 4 [21]. There was no major diminution of the desirable luminescence properties of the iridium complexes (high emission quantum yields of 0.23 and lifetimes of about a microsecond). Similar results have been reported for aluminum and boron 8-hydroxy quinoline complexes tethered to polystyrene using Schiff base condensation [22]. 

In a similar way the pinene-phenylpyridine H[46] was prepared. Thus upon treatment of 4,5-(/f,/f)-pinene-2-phenylpyridine H[46] with IrCls.SHaO, the HEXOL-type tetranuclear iridium complexes [Ir IrCl2(46)2 3] were obtained as two isomers (5.67ab) in a ratio of 5 3 (Scheme 5.25). Each complex can be described as an inner core of HEXOL-type [Ir(IrCl2)3] units and a surface of six chiral bidentate cyclometallated ligands (46). 

K. Dedeian, P.I. Djurovich, F.O. Garces, G. Carlson, and R.J. Watts, A new synthetic route to the preparation of a series of strong photoreducing agents fac tris-ortho-metalated complexes of Iridium (III) with substituted 2-phenylpyridines, Inorg. Chem., 30 1685-1687 (1991). 

A broad range of metal centers have been used for the complexation of functional ligands, including beryllium [37], zinc, transition metals such as iridium [38], and the lanthanide metals introduced by Kido [39], especially europium and terbium. Common ligands are phenanthroline (phen), bathophenanthrolin (bath), 2-phenylpyridine (ppy), acetylacetonate (acac), dibenzoylmethanate (dbm), and 11 thenoyltrifluoroacetonate (TTFA). A frequently used complex is the volatile Eu(TTFA)3(phen), 66 [40]. 

A series of iridium(III) complexes of the type Ir(L-L)3 have been prepared by reaction of a glycerol solution of Ir(acac)3 and L-L (2-arylpyridine or 2-aryl-l-qui-noline) in an open vessel equipped with a reflux condenser. 5 This represented an improvement on the analogous methodology using a domestic microwave oven as less ligand was required, but YIFs were only 0.82-1.2. In the case of 2-phenyl-l-quin-oline, a 10% yield of the Ir complex was obtained in 20 min, while only trace amounts were produced after 10 h of conventional reflux. Cyclometallated platinum(II) complexes of the type PtCl(L-L)L where L-L = 2-phenylpyridine, 2-(2 -thienyl)pyridine, or benzoquinoline have also been prepared but not with any enhancement in yield (YIF = 0.58-1.0). 55... 

Luminescent organometallic complexes used for cell imaging can be divided in two main families, namely (i) carbonyl complexes, most commonly octahedral rhenium c-tricarbonyl derivatives incorporating a polypyridine ligand and (ii) cyclometalated complexes such as iridium and platinum derivatives containing the ubiquitous 2-phenylpyridine unit (complexes 1-3 in Scheme 11.2). 

Solution processable cyclotriphosphazene OLEDs can be formed through direct substitution at phosphorus Polyaromatic substituted phosphazene (2) has one pendant group containing nitrogen for potential complexation with a metal. In this example, two 2-phenylpyridine ligands are complexed to the iridium metal center. 

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