5599-50-8Relevant articles and documents
Synthesis and characterization of carbazolide-based iridium PNP pincer complexes. Mechanistic and computational investigation of alkene hydrogenation: Evidence for an Ir(III)/Ir(V)/Ir(III) catalytic cycle
Cheng, Chen,Kim, Bong Gon,Guironnet, Damien,Brookhart, Maurice,Guan, Changjian,Wang, David Y.,Krogh-Jespersen, Karsten,Goldman, Alan S.
, p. 6672 - 6683 (2014)
New carbazolide-based iridium pincer complexes (carbPNP) Ir(C2H4), 3a, and (carbPNP)Ir(H)2, 3b, have been prepared and characterized. The dihydride, 3b, reacts with ethylene to yield the cis-dihydride ethylene complex cis-(carbPNP) Ir(C2H4)(H)2. Under ethylene this complex reacts slowly at 70 C to yield ethane and the ethylene complex, 3a. Kinetic analysis establishes that the reaction rate is dependent on ethylene concentration and labeling studies show reversible migratory insertion to form an ethyl hydride complex prior to formation of 3a. Exposure of cis-( carbPNP)Ir(C2H4)(H)2 to hydrogen results in very rapid formation of ethane and dihydride, 3b. DFT analysis suggests that ethane elimination from the ethyl hydride complex is assisted by ethylene through formation of (carbPNP)Ir(H)(Et)(C2H 4) and by H2 through formation of (carbPNP) Ir(H)(Et)(H2). Elimination of ethane from Ir(III) complex ( carbPNP)Ir(H)(Et)(H2) is calculated to proceed through an Ir(V) complex (carbPNP)Ir(H)3(Et) which reductively eliminates ethane with a very low barrier to return to the Ir(III) dihydride, 3b. Under catalytic hydrogenation conditions (C2H4/H 2), cis-(carbPNP)Ir(C2H4)(H) 2 is the catalyst resting state, and the catalysis proceeds via an Ir(III)/Ir(V)/Ir(III) cycle. This is in sharp contrast to isoelectronic (PCP)Ir systems in which hydrogenation proceeds through an Ir(III)/Ir(I)/Ir(III) cycle. The basis for this remarkable difference is discussed.
Effect ofortho-biphenyl substitution on the excited state dynamics of a multi-carbazole TADF molecule
Ha, Yeon-Hee,Kim, Jang-Joo,Kim, Yun-Hi,Woo, Seung-Je
, p. 12075 - 12084 (2020)
We report a new thermally activated delayed fluorescence (TADF) molecule developed by theortho-biphenyl substitution of a multi-carbazole TADF molecule. The new TADF molecule,4mCzBN-BP, is composed of four dimethylcarbazole donors, a benzonitrile acceptor core and anortho-biphenyl triplet scaffold.4mCzBN-BPexhibits a bluish-green emission with a peak wavelength at 491 nm and a very high photoluminescence quantum yield (PLQY) of 95% in an mCBP host. To investigate the effect of theortho-biphenyl substitution on the excited-state dynamics and photophysical properties of the TADF molecule, we performed time dependent density functional theory (TD-DFT) calculations of4mCzBN-BPand two multi-carbazole TADF molecules with similar molecular structures. A local excited triplet state (3LE) with an energy (2.81 eV) close to the lowest singlet charge-transfer state (1CT) can be formed at the biphenyl of4mCzBN-BP. However, due to the planarization of the biphenyl at the triplet state and a large steric hindrance caused by adjacent carbazole donors,3LE at the biphenyl can only be formed by a subset of possible conformations of4mCzBN-BPmolecules in the solid mCBP host, leading to a multiexponential decay of the delayed fluorescence. Color coordinates of (0.196, 0.452), a high external quantum efficiency of 23.7% and a long operational lifetime (LT50) of 750 hours were achieved with the organic light emitting diodes based on4mCzBN-BP.
Site-Specific Synthesis of Carbazole Derivatives through Aryl Homocoupling and Amination
Baek, Junghyun,Ban, Jaeyoung,Lim, Minkyung,Rhee, Hakjune,Shabbir, Saira
, p. 917 - 927 (2020/03/13)
We synthesized various carbazoles from anilines through a three-step process with good overall yields (up to 48percent). This process comprises N -acetylation, copper(0)-mediated Ullmann homocoupling, and acid-mediated intramolecular amination. It permits various functional groups on the substrate. Scale-up of the developed three-step synthetic route to carbazoles was also demonstrated.
Ruthenium-catalyzed cross-dehydrogenative ortho-N-carbazolation of diarylamines: Versatile access to unsymmetrical diamines
Louillat, Marie-Laure,Biafora, Agostino,Legros, Fabien,Patureau, Frederic W.
supporting information, p. 3505 - 3509 (2014/04/03)
The dehydrogenative C-N cross-coupling of unprotected, secondary anilines through ortho-N-carbazolation has been achieved using a Ru catalytic system with O2 as the terminal oxidant. The reactions proceed in an intermolecular fashion, selectively in the ortho position. Implications for the field of organic synthesis are discussed. No-No-No: Amination of a non-acidic Ci￡H bond, no pre-activation of the coupling partners, no chelate-assisting directing group. Dehydrogenative C-N cross-coupling through the ortho-N-carbazolation of unprotected, secondary anilines has been achieved using a Ru catalyst with O2 as the terminal oxidant. The reactions proceed in an intermolecular fashion, selectively in the ortho position.
