53897-95-3Relevant articles and documents
Neutral Cyclometalated Iridium(III) Complexes Bearing Substituted N-Heterocyclic Carbene (NHC) Ligands for High-Performance Yellow OLED Application
Liu, Bingqing,Jabed, Mohammed A.,Guo, Jiali,Xu, Wan,Brown, Samuel L.,Ugrinov, Angel,Hobbie, Erik K.,Kilina, Svetlana,Qin, Anjun,Sun, Wenfang
, p. 14377 - 14388 (2019/11/03)
The synthesis, crystal structure, and photophysics of a series of neutral cyclometalated iridium(III) complexes bearing substituted N-heterocyclic carbene (NHC) ancillary ligands ((CN)2Ir(R-NHC), where CN and NHC refer to the cyclometalating ligand benzo[h]quinoline and 1-phenylbenzimidazole, respectively) are reported. The NHC ligands were substituted with electron-withdrawing or -donating groups on C4′ of the phenyl ring (R = NO2 (Ir1), CN (Ir2), H (Ir3), OCH3 (Ir4), N(CH3)2 (Ir5)) or C5 of the benzimidazole ring (R = NO2 (Ir6), N(CH3)2 (Ir7)). The configuration of Ir1 was confirmed by a single-crystal X-ray diffraction analysis. The ground- and excited-state properties of Ir1-Ir7 were investigated by both spectroscopic methods and time-dependent density functional theory (TDDFT) calculations. All complexes possessed moderately strong structureless absorption bands at ca. 440 nm that originated from the CN ligand based 1π,π*/1CT (charge transfer)/1d,d transitions and very weak spin-forbidden 3MLCT (metal-to-ligand charge transfer)/3LLCT (ligand-to-ligand charge transfer) transitions beyond 500 nm. Electron-withdrawing substituents caused a slight blue shift of the 1π,π*/1CT/1d,d band, while electron-donating substituents induced a red shift of this band in comparison to the unsubstituted complex Ir3. Except for the weakly emissive nitro-substituted complexes Ir1 and Ir6 that had much shorter lifetimes (≤160 ns), the other complexes are highly emissive in organic solutions with microsecond lifetimes at ca. 540-550 nm at room temperature, with the emitting states being predominantly assigned to 3π,π*/3MLCT states. Although the effect of the substituents on the emission energy was insignificant, the effects on the emission quantum yields and lifetimes were drastic. All complexes also exhibited broad triplet excited-state absorption at 460-700 nm with similar spectral features, indicating the similar parentage of the lowest triplet excited states. The highly emissive Ir2 was used as a dopant for organic light-emitting diode (OLED) fabrication. The device displayed a yellow emission with a maximum current efficiency (ηc) of 71.29 cd A-1, a maximum luminance (Lmax) of 32747 cd m-2, and a maximum external quantum efficiency (EQE) of 20.6%. These results suggest the potential of utilizing this type of neutral Ir(III) complex as an efficient yellow phosphorescent emitter.
SMALL MOLECULE COMPOUNDS FOR STEM CELL DIFFERENTIATION
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Page/Page column 53; 54, (2010/04/25)
Methods and small molecule compounds for stem cell differentiation are provided. One example of a class of compounds that may be used is represented by the compound having the structure IA or IB in the form of free base or a pharmaceutically acceptable salt, hydrate, solvate or N-oxide thereof. R1 is independently hydrogen or (C1-C6)alkyl; R2 is independently hydrogen, (C1-C6)alkyl, aryl, or heteroaryl; R2' is independently hydrogen, (C1-C6)alkyl, CF3 or C2F5; R3 is independently (C1-C6)alkyl, aryl, 2-tetrahydrofuryhnethyl, an aliphatic tertiary amine, or 4-methoxybenzyl; or R2 and R3 may be joined together to form a 5 or 6 member ring lactone; R4 is independently hydrogen, (C1-C6)alkyl, a 2- or 4-R5-substituted aromatic ring selected from a 4-R5-phenyl or a 2-R5-5-pyridyl, aryl, heteroaryl, aliphatic tertiary amine or halogen; and R5, R5', R6, R6', R7, R7' are each independently hydrogen, (C1-C6)alkyl, aryl, optionally substituted phenyl, heteroaryl, a heterocyclic ring, an aliphatic tertiary amine, or halogen.
