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Liang X, Liu Z, Xia Y, Li D, Li J, Wang H, Zhang Z, Wang S, Zhao B, Li Z, Xing Y, Guo K. Lifting Triplet Energy and Bipolar Characteristics by Limiting the Rotation of the Peripheral Groups in Host Materials to Achieve High-Efficiency Blue OLED. Chem Asian J 2021; 17:e202101298. [PMID: 34964279 DOI: 10.1002/asia.202101298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/20/2021] [Indexed: 11/08/2022]
Abstract
Bipolar host materials with high triplet energy are of great significance for highly efficient blue organic light-emitting diodes (OLEDs). In this work, three donor-acceptor-donor (D-A-D) type host materials with identical non-rigid diphenylsulfone center but differing in rotation degree of peripheral amino substituted derivatives from rotating freely diphenylamine (SODP) to rotating partially iminodibenzyl (SOId) and rotating restricted carbazole (SOCz) were designed and synthesized. It was demonstrated that the triplet energy (ET ) level of the materials promoted by limiting the rotation degree of the peripheral groups, which was 2.72 eV for SODP, 2.73 eV for SOId and 2.78 eV for SOCz, respectively. Besides, the results of the single-carrier devices indicate SOCz possess better bipolar characteristic. Using FIrpic as guest emitter, the blue OLED with SOCz as host material exhibited superior device performance with a low turn-on voltage of 3.3 V, a maximum current efficiency (CE) of 30.1 cd A-1 , a maximum power efficiency (PE) of 32.2 lm W-1 , and a maximum external quantum efficiency (EQE) of 14.0%. This work provides a beneficial guideline for realizing promising host materials in efficient blue OLEDs.
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Affiliation(s)
- Xiaozhong Liang
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Zemei Liu
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Yan Xia
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Da Li
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Jie Li
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Hua Wang
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Zheng Zhang
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Sijing Wang
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Bo Zhao
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Zhijun Li
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Yifan Xing
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
| | - Kunpeng Guo
- Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, 030024, Taiyuan, P. R. China
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Blazevicius D, Tavgeniene D, Sutkuviene S, Zaleckas E, Jiang MR, Swayamprabha SS, Yadav RAK, Jou JH, Grigalevicius S. Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs. Molecules 2021; 26:4615. [PMID: 34361768 DOI: 10.3390/molecules26154615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 11/29/2022] Open
Abstract
Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m2. The most efficient green PhOLED with 10 wt% of Ir(ppy)3 {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m2, which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.
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Vieira AA, Farias G, Costa WC, Eccher J, Bechtold IH, Durola F, Bock H. Nematic Triphenyltriazine Triesters and the Induction of the Columnar Mesophase by Fluorine Substitution. Chemistry 2021; 27:9003-9010. [PMID: 33871125 DOI: 10.1002/chem.202005456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Indexed: 11/06/2022]
Abstract
Whereas their para homologs are not mesogenic, the disk-shaped triphenyltriazine meta-trialkylesters obtained via trimerization of 3-cyanobenzoic alkylester, which are configurationally more flexible, exhibit a monotropic nematic mesophase. Introduction of fluorine atoms into the alkyl chains or into the phenyl moieties leads to the appearance of an enantiotropic columnar mesophase. If fluorine is introduced both in the chains and in the phenyl moieties, only a monotropic mesophase remains. Fluorination of either the alkyl chains or the aromatic core, but not both, appears thus as a simple means of inducing or stabilizing columnar self-assembly in disk-shaped systems. As the homeotropically alignable columnar mesophase can thus be made to persist at room temperature, as energies higher than 3 eV of the first excited triplet state are computed in agreement with the value reported for the parent arene, and as they are not fluorescent themselves, these compounds are of promise as aligning host matrices for blue-emitting TADF devices with improved light outcoupling. Dilution of a columnar with a nonmesogenic homolog induces the nematic state, indicating that the nanoscopic make-up of both mesophases is closely related.
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Affiliation(s)
- André A Vieira
- Instituto de Química, Universidade Federal da Bahia, 40170-115, Salvador, BA, Brazil
| | - Giliandro Farias
- Departamento de Química, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Wallison C Costa
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Juliana Eccher
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Ivan H Bechtold
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Fabien Durola
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
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Park KM, Yang K, Moon SH, Kang Y. Structures and photophysical properties of two luminescent bipyridine compounds: 2',6'-difluoro-6-[3-(pyridin-2-yloxy)phenyl]-2,3'-bipyridine and 2',6'-dimethoxy-6-[3-(pyridin-2-yloxy)phenyl]-2,3'-bipyridine. Acta Crystallogr C Struct Chem 2020; 76:381-388. [PMID: 32367817 DOI: 10.1107/s2053229620004301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/30/2020] [Indexed: 11/10/2022]
Abstract
The title compounds, C21H13F2N3O (1) and C23H19N3O3 (2), have been synthesized by typical cross-coupling reactions. Both compounds have been characterized by single-crystal X-ray diffraction. Bipyridine 1 exhibits a fully extended structure in which the terminal pyridine rings are oriented away from each other, while bipyridine 2 displays a bent structure in which terminal pyridine rings are oriented in the same direction. Several intermolecular interactions lead to the formation of two- and three-dimensional supramolecular networks in the crystal structures of 1 and 2, respectively. Compound 1 bears fluorine substituents and emits a strong fluorescence with λmax = 325 nm, while methoxy-substituted compound 2 displays red-shifted emissions with λmax = 366 nm. The emissions observed in both compounds originate from phenyl- and 2,3'-bipyridine-based π-π* transitions, according to theoretical calculations. Both compounds have high triplet energies (T1) ranging from 2.64 to 2.65 eV, which makes them potential host materials in organic light-emitting diodes (OLEDs).
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Affiliation(s)
- Ki Min Park
- Research Institute of Natural Science & Department of Chemistry Education, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Kiyull Yang
- Research Institute of Natural Science & Department of Chemistry Education, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Suk Hee Moon
- Department of Food and Nutrition, Kyungnam College of Information and Technology, Busan 47011, Republic of Korea
| | - Youngjin Kang
- Division of Science Education, Kangwon National University, Chuncheon 24341, Republic of Korea
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Liu XY, Zhang YJ, Fei X, Fung MK, Fan J. Four-Coordinate Organoboron Platforms for Efficient Red Phosphorescent Organic Light-Emitting Diodes. Chempluschem 2020; 84:1587-1595. [PMID: 31943932 DOI: 10.1002/cplu.201900406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/16/2019] [Indexed: 11/11/2022]
Abstract
So far both three- and four-coordinate organoboron compounds have been widely applied in organic light-emitting diode (OLED) materials. However, the use of four-coordinate organoboron compounds as host materials is rarely reported. In this work, two new four-coordinate organoboron compounds, namely 8-(4-(9H-carbazol-9-yl)phenyl)-6,6-difluoro-6H-6λ4 ,7λ4 -benzo[4',5']imidazo[1',2':3,4][1,3,2]diazaborolo[1,5-a]pyridine (B1PCz) and 8-(3-(9H-carbazol-9-yl)phenyl)-6,6-difluoro-6H-6λ4 ,7λ4 -benzo[4',5']imidazo[1',2':3,4][1,3,2]diazaborolo[1,5-a]pyridine (B1MCz), were successfully designed, synthesized, and fully characterized. The red OLEDs using B1PCz and B1MCz as host materials achieved relatively high device performance with a maximum external quantum efficiency of 14.8 % and 11.8 %, respectively. These results will expand the scope of organoboron compounds for OLED materials and reveal the great potential of four-coordinate organoboron materials.
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Affiliation(s)
- Xiang-Yang Liu
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu, 215123, P. R. China.,Suzhou Ever Display Advanced Materials Co., Ltd. Wujiang, Suzhou, Jiangsu, 215000, P. R. China
| | - Yi-Jie Zhang
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu, 215123, P. R. China.,Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Xiyu Fei
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu, 215123, P. R. China.,Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Man-Keung Fung
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu, 215123, P. R. China.,Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
| | - Jian Fan
- Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu, 215123, P. R. China.,Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu, 215123, P. R. China
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Antusch L, Gaß N, Wagenknecht HA. Elucidation of the Dexter-Type Energy Transfer in DNA by Thymine-Thymine Dimer Formation Using Photosensitizers as Artificial Nucleosides. Angew Chem Int Ed Engl 2016; 56:1385-1389. [PMID: 28026075 DOI: 10.1002/anie.201610065] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 11/28/2016] [Indexed: 01/26/2023]
Abstract
C-nucleosides of 4-methylbenzophenone, 4-methoxybenzophenone, and 2'-methoxyacetophenone were synthetically incorporated as internal photosensitizers into DNA double strands. This structurally new approach makes it possible to study the distance dependence of thymidine dimer formation because the site of photoinduced triplet energy transfer injection is clearly defined. The counterstrands to these modified strands lacked the phosphodiester bond between the two adjacent thymidines that are supposed to react with each other. Their dimerization could be evidenced by gel electrophoresis because the covalent connection by cyclobutane formation between the two thymidines changes the mobility. A shallow exponential distance dependence for the formation of thymidine dimers over up to 10 A-T base pairs was observed that agrees with a Dexter-type triplet-triplet energy transfer mechanism. Concomitantly, a significant amount of photoinduced DNA crosslinking was observed.
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Affiliation(s)
- Linda Antusch
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Nadine Gaß
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
| | - Hans-Achim Wagenknecht
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131, Karlsruhe, Germany
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Lee DR, Choi JM, Lee CW, Lee JY. Ideal Molecular Design of Blue Thermally Activated Delayed Fluorescent Emitter for High Efficiency, Small Singlet- Triplet Energy Splitting, Low Efficiency Roll-Off, and Long Lifetime. ACS Appl Mater Interfaces 2016; 8:23190-23196. [PMID: 27529181 DOI: 10.1021/acsami.6b05877] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Highly efficient thermally activated delayed fluorescent (TADF) emitters, 5-(2-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (oBFCzTrz), 5-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (mBFCzTrz), and 5-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5H-benzofuro[3,2-c]carbazole (pBFCzTrz), were synthesized to study the effects of ortho-, meta-, and para- linkages between donor and acceptor moieties. oBFCzTrz having ortho- linked donor and acceptor moieties showed smaller singlet-triplet energy gap, shorter excited state lifetime, and higher photoluminescence quantum yield than mBFCzTrz and pBFCzTrz which are interconnected by meta- and para- positions. The TADF device using oBFCzTrz as a blue emitter exhibited high external quantum efficiency over 20%, little efficiency roll-off, and long device lifetime.
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Affiliation(s)
- Dong Ryun Lee
- School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea
| | - Jeong Min Choi
- School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea
| | - Chil Won Lee
- Department of Polymer Science and Engineering, Dankook University , 126 Jukjeon-dong, Suji-gu, Yongin, Gyeonggi 448-701, Korea
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University , 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi 440-746, Korea
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Jhulki S, Seth S, Ghosh A, Chow TJ, Moorthy JN. Benzophenones as Generic Host Materials for Phosphorescent Organic Light-Emitting Diodes. ACS Appl Mater Interfaces 2016; 8:1527-1535. [PMID: 26690799 DOI: 10.1021/acsami.5b11232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Despite the fact that benzophenone has traditionally served as a prototype molecular system for establishing triplet state chemistry, materials based on molecular systems containing the benzophenone moiety as an integral part have not been exploited as generic host materials in phosphorescent organic light-emitting diodes (PhOLEDs). We have designed and synthesized three novel host materials, i.e., BP2-BP4, which contain benzophenone as the active triplet sensitizing molecular component. It is shown that their high band gap (3.91-3.93 eV) as well as triplet energies (2.95-2.97 eV) permit their applicability as universal host materials for blue, green, yellow, and red phosphors. While they serve reasonably well for all types of dopants, excellent performance characteristics observed for yellow and green devices are indeed the hallmark of benzophenone-based host materials. For example, maximum external quantum efficiencies of the order of 19.2% and 17.0% were obtained from the devices fabricated with yellow and green phosphors using BP2 as the host material. White light emission, albeit with rather poor efficiencies, has been demonstrated as a proof-of-concept by fabrication of co-doped and stacked devices with blue and yellow phosphors using BP2 as the host material.
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Affiliation(s)
- Samik Jhulki
- Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India
| | - Saona Seth
- Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India
| | - Avijit Ghosh
- Institute of Chemistry, Academia Sinica , Taipei, Taiwan 115, Republic of China
| | - Tahsin J Chow
- Institute of Chemistry, Academia Sinica , Taipei, Taiwan 115, Republic of China
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Neogi I, Jhulki S, Ghosh A, Chow TJ, Moorthy JN. Amorphous host materials based on Tröger's base scaffold for application in phosphorescent organic light-emitting diodes. ACS Appl Mater Interfaces 2015; 7:3298-3305. [PMID: 25585169 DOI: 10.1021/am508004n] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Tröger's bases (TBs) functionalized with carbazoles (TB-Czs) and phosphine oxides (TB-POs) were designed and synthesized as host materials for application in phosphorescent organic light-emitting diodes. The TB scaffold is shown to impart thermal stability with high Tg values (171-211 °C) as well as high triplet energies in the range of 2.9-3.0 eV. With a limited experimentation of the devices, it is shown that the TBs doped with a green phosphor, namely, Ir(ppy)3, permit impressive external efficiencies on the order of ca. 16% with a high brightness of ca. 3000-4000 cd/m2. Better device performance results are demonstrated by a small structural manipulation of the TB scaffold involving substitution of methyl groups in the core scaffold.
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Affiliation(s)
- Ishita Neogi
- Department of Chemistry, Indian Institute of Technology , Kanpur 208016, India
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