- n-Type host materials based on nitrile and triazine substituted tricyclic aromatic compounds for high-performance blue thermally activated delayed fluorescence devices
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Novel n-type host materials based on tricyclic aromatic compounds, dibenzo[b,d]furan and dibenzo[b,d]thiophene (2Trz6CNDBF and 2Trz6CNDBT), have been successfully synthesized and characterized for high-performance blue thermally activated delayed fluorescence (TADF) organic light-emitting devices (OLEDs). Dibenzo[b,d]furan and dibenzo[b,d]thiophene were utilized as central molecular building blocks to achieve excellent thermal stability and high triplet energy (ET). Nitrile and diphenyltriazine functional groups were introduced at the 6- and 2- positions of the central building blocks to achieve low-lying lowest unoccupied molecular orbital (LUMO) energy levels, high ET, and excellent electron transport properties. UV–Vis absorption, low-temperature photoluminescence, and ultraviolet photoelectron spectroscopy analysis showed that 2Trz6CNDBF and 2Trz6CNDBT possessed high ET (2.95 and 2.88 eV) and low-lying LUMO energy levels (?3.43 and ?3.16 eV) that were well-matched with a blue TADF emitter, 5CzCN. Moreover, the electron-only device (EOD) result revealed that 2Trz6CNDBF and 2Trz6CNDBT had excellent electron transport properties. Blue TADF OLEDs fabricated with a p-type host material, mCBP, and n-type host, 2Trz6CNDBF or 2Trz6CNDBT, exhibited lower driving voltages (3.34 and 3.26 V, respectively) than a TADF OLED with only a p-type host material, mCBP (3.83 V). Blue TADF OLEDs with 2Trz6CNDBF and 2Trz6CNDBT exhibited superior external quantum efficiency (ηext, 15.6 and 14.7%), current efficiency (ηce, 33.8 and 32.7 cd A?1), and power efficiency (ηpe, 25.6 and 25.7 lm W?1), respectively. The ηext and ηce of blue TADF OLEDs with 2Trz6CNDBF and 2Trz6CNDBT increased by more than 70% and ηpe by approximately 150% compared to those of the TADF OLED with a single p-type host, mCBP. In addition, the device lifetimes of blue TADF OLEDs with 2Trz6CNDBF and 2Trz6CNDBT increased by more than 1000%. The efficient electron injection by the low-lying LUMO energy level, effective exciton confinement by high ET, and high thermal stability of the film morphology provided the enhanced efficiency and lifetime for blue TADF OLEDs with 2Trz6CNDBF and 2Trz6CNDBT.
- Hong, Soojin,Jang, Seokhoon,Lee, Jun Yeob,Lee, Kyung Hyung,Lee, Youngu
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- Ligand-Promoted Non-Directed C?H Cyanation of Arenes
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This article reports the first example of a 2-pyridone accelerated non-directed C?H cyanation with an arene as the limiting reagent. This protocol is compatible with a broad scope of arenes, including advanced intermediates, drug molecules, and natural products. A kinetic isotope experiment (kH/kD=4.40) indicates that the C?H bond cleavage is the rate-limiting step. Also, the reaction is readily scalable, further showcasing the synthetic utility of this method.
- Liu, Luo-Yan,Yeung, Kap-Sun,Yu, Jin-Quan
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supporting information
p. 2199 - 2202
(2019/01/24)
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- Cyanation of aromatic/vinylic boronic acids with α-cyanoacetates
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A friendly protocol is reported to achieve cyanation of aromatic and vinylic boronic acids using nontoxic and readily available α-cyanoacetates as a cyano source under aerobic conditions. Many aryl/vinyl boronic acids (as well as some iodides and bromides) are amenable substrates to give aryl nitriles and acrylonitriles. This cyanation method provides a safe and operationally convenient alternative to traditional ones requiring toxic cyanide salts.
- Wang, Xian-Jin,Zhang, Song-Lin
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supporting information
p. 14826 - 14830
(2017/12/15)
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- Aryl Nitriles from Alkynes Using tert -Butyl Nitrite: Metal-Free Approach to C≡C Bond Cleavage
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Alkyne C≡C bond breaking, outside of alkyne metathesis, remains an underdeveloped area in reaction discovery. Recently, nitrogenation has been reported to allow nitrile formation from alkynes. A new protocol for the metal-free C≡C bond cleavage of terminal alkynes to produce nitriles is reported. This method provides an opportunity to synthesize a vast range of nitriles containing aryl, heteroaryl, and natural product derivatives (38 examples). In addition, the potential of tBuONO to act as a powerful nitrogenating agent for terminal aryl alkynes is demonstrated. (Figure Presented).
- Dutta, Uttam,Lupton, David W.,Maiti, Debabrata
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p. 860 - 863
(2016/03/01)
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- Copper-Catalyzed Cyanation of Aryl- and Alkenylboronic Reagents with Cyanogen Iodide
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Direct catalytic cyanation of organoboronic acids with cyanogen iodide has been achieved by using a copper-bipyridine catalyst system. The cyanation reaction is likely to occur through two catalytic cycles: copper(II)-catalyzed iodination of organoboronic acids and the following cyanidocopper(I)-mediated cyanation of organic iodides.
- Okamoto, Kazuhiro,Sakata, Naoki,Ohe, Kouichi
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supporting information
p. 4670 - 4673
(2015/10/12)
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- NOVEL HETEROLEPTIC IRIDIUM COMPLEXE
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Novel heteroleptic iridium complexes are disclosed. The complexes contain a phenyl pyridine ligand and another ligand containing a dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole linked to an imidazole or benzimidazole fragment. These complexes are useful materials when incorporated into OLED devices.
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Page/Page column
(2013/07/25)
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- One-pot Synthesis of Dibenzofurans via SNAr and Subsequent Ligand-free Palladium-catalyzed Intramolecular Aryl-aryl Cross-coupling Reactions under Microwave Irradiation
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An efficient one-pot synthesis of dibenzofurans, via SNAr reaction of aryl halides and ortho-bromophenols in the presence of anhydrous K2CO 3 and subsequent ligand-free palladium-catalyzed intramolecular aryl-aryl cross-coupling cyclization under microwave irradiation, is described.
- Che, Zhiping,Xu, Hui
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experimental part
p. 833 - 836
(2011/10/05)
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- Propylphosphonic anhydride (T3P): A remarkably efficient reagent for the one-pot transformation of aromatic, heteroaromatic, and aliphatic aldehydes to nitriles
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Propylphosphonic anhydride has been demonstrated to be an efficient reagent for the transformation of aromatic, heteroaromatic, and aliphatic aldehydes to respective nitriles in excellent yields. This procedure offers simple and one-pot access to nitriles and highlights the synthetic utility of T3P as a versatile reagent in organic chemistry. Georg Thieme Verlag Stuttgart - New York.
- Augustine, John Kallikat,Atta, Rajendra Nath,Ramappa, Balakrishna Kolathur,Boodappa, Chandrakantha
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experimental part
p. 3378 - 3382
(2010/03/03)
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- Synthesis of dibenzofurans directly from aryl halides and ortho-bromophenols via one-pot consecutive SNAr and intramolecular palladium-catalyzed aryl-aryl coupling reactions
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A series of dibenzofurans were efficiently and conveniently synthesized via one-pot consecutive C(sp2)-O bond formation reaction (SNAr) in the presence of anhydrous K2CO3, followed by C(sp 2)-C(sp2) b
- Xu, Hui,Fan, Ling-Ling
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experimental part
p. 1496 - 1498
(2009/10/16)
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