Novel phosphorescent triptycene-based Ir(iii) complexes for organic light-emitting diodes.

A series of charge-neutral cyclometalated iridium(iii) complexes (1-3 and 5-7) containing triptycene-substituted ligands (tbt and tpbi) and two parent complexes (4 and 8) were synthesized and characterized. The crystal structures indicated that π-π stacking interactions existed in ligand tbtH, but not in complex 6. However, a large intramolecular repulsion was found in complex 6. These triptycene-based complexes exhibited good thermal stability, which was higher compared with that of the parent complexes. These complexes showed green to yellow emission with peaks that ranged from 503 to 563 nm. The introduction of the rigid non-conjugate triptycene skeleton caused a slight emission red shift (<25 nm), but a significant increase in the PLQYs (>47%) was observed. The electroluminescent devices employing 2 and 6 as phosphors displayed impressive performance improvements and low efficiency roll-off because of the higher PLQYs and HOMO levels of these triptycene-based complexes. The maximum current and external quantum efficiencies of the devices based on complexes 2 and 6 were 41.7 cd A-1, 11.9% and 41.2 cd A-1, 12.6%, respectively, which were about 31% higher than that of the devices based on the parent complexes 4 and 8. This work provides a novel approach to develop highly efficient phosphors with a triptycene skeleton.

Phosphorescent chemosensor for Hg2+ and acetonitrile based on iridium(III) complex.

A new phosphorescent chemosensor for Hg(2+) and acetonitrile (MeCN) based on iridium(III) complex Ir(dpp)(2)(dtc) (Ir1, dppH = 4,6-diphenylpyrimidine, dtcH = diethyl dithiocarbamic acid) was realized. Upon addition of a tetrahydrofuran (THF) solution of Hg(2+), the dichloromethane (DCM) solution of Ir1 gave a visual color change and significant fluorescent quenching. When MeCN was added, a new fluorescent emission emerged, which constituted a selective MeCN phosphorescent chemosensor. Complex Ir1 has been developed as an AND logic gate with Hg(2+) and MeCN as inputs.

Chemiluminescence of a cyclometallated iridium(III) complex and its application in the detection of cysteine.

Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10(-9) -5.0 × 10(-6) mol/L with a detection limit of 6.9 × 10(-10) mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex.

Enhancing and inhibiting effects of benzenediols on chemiluminescence of a novel cyclometallated iridium(III) complex.

A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10(-8), 2.7 × 10(-9) and 8.1 × 10(-7) mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal-ligand charge-transfer (MLCT) excited state of the iridium complex.