Emissive Iridium(III) Diimine Complexes Formed by Double Cyclometalation of Coordinated Triphenylphosphite

Abstract

We report on the synthesis of a new series of iridium(III) complexes functionalized with various diimine chromophores, together with a facially coordinated dicyclometalated phosphite chelate and a monodentate anionic ancillary. This conceptual design presents a novel strategy in obtaining a new class of iridium(III) diimine complexes without employment of traditional nitrogen-containing polyaromatic cyclometalates. Additionally, we discuss the basic charactersistics of the ground and lower-lying excited states involved, as documented by crystal structural, photophysical studies, and density functional theory calculations. Fabrication of the green-emitting organic light-emitting diodes with one such dopant, [Ir(dbbpy)(tpit)NCS] (2b), where dbbpy and tpit represent di-tert-butyl-2,2'-bipyridine and dicyclometalated triphenylphosphite, respectively, was successfully made, attaining a peak external quantum efficiency (η(ext)), a luminance efficiency (η(l)), and a power efficiency (η(p)) of 14.1%, 46.6 cd A(-1), and 39.9 lm W(-1), respectively.

Sky Blue-Emitting Iridium(III) Complexes Bearing Nonplanar Tetradentate Chromophore and Bidentate Ancillary

“…[Ir(dpyx)(dfppy)Cl] (Scheme 2). By contrast, Chi and co-workers 25,26 and Guerchais and Zysman-Colman 27 have independently reported the isolation of a class of Ir(III) complexes with chelates arranged in a distinctive 3 + 2 + 1 mode, for example, complexes A and B, where the "nonplanar" tridentate chelate adopts a distinctive facial geometry. With this success in changing chelate from bidentate to tridentate and altering their bonding from meridional to facial coordination, it is clear that preparation of Ir(III) complexes bearing tetradentate chelate in either planar or nonplanar geometries should be also accessible.…”

Mechanistic Investigation of Improved Syntheses of Iridium(III)-Based OLED Phosphors

“…Recently, in sharp contrast to the triphenyl phosphite that yields double cyclometalation, , a bulky phosphine ligand such as PPh 3 , was found to react readily with the aforementioned Ir(III) source complex [Ir(tht) 3 Cl 3 ], giving two isolable products, namely [Ir(tht) 2 (PPh 3 )Cl 3 ] ( 5 ) and [Ir(tht)(PPh 3 ) 2 Cl 3 ] ( 6 ), in a stepwise fashion (Scheme ). The monosubstitution product 5 was obtained as the major product for the reaction using a stoichiometric amount of PPh 3 , while the disubstitution product 6 was isolated by addition of 2 equiv of PPh 3 to [Ir(tht) 3 Cl 3 ] or by treatment of the monosubstitution product 5 with a another 1 equiv of PPh 3 under similar conditions.…”

Stepwise Formation of Iridium(III) Complexes with Monocyclometalating and Dicyclometalating Phosphorus Chelates

“…It was reported that treatment of [IrCl 3 (tht) 3 ] (tht = tetrahydrothiophene) with an equimolar amount of triphenylphosphite (tpitH 2 ) and diimine, such as 2,2′-bipyridine and 2,2′-biquinoline, gave formation of novel diimine complexes A and B (see below) in high yields . The added diimine and phosphite would easily replace all three tht ligands and then formed certain unknown intermediate initially.…”