- Ultra-small sugar-substituted N-heterocyclic carbene-protected palladium nanoparticles and catalytic activity
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Ultra-small Pd nanoparticles (UNPs) represent a distinctive type of nanomaterial making them very attractive for a range of applications. Herein, chiral sugar-substituted N-heterocyclic carbenes (NHCs) with various lengths of alkyl chain (sugar-NHCs-nCnH2n+1) were first used to prepare water-soluble Pd@NHCs-sugar UNPs via an efficient ligand-exchange strategy, which can be handled under air and are stable over 10?months. The Pd@NHCs-sugar UNPs were highly monodisperse, with tunable core diameters from 1.7 to 2.1?nm, and an effect of the particle size on the N-substituted aliphatic chains was observed. To investigate the accessibility of the surface, the Pd@NHCs-sugar UNPs were studied as catalysts for C–C coupling reaction in eco-friendly ethanol aqueous solution without any precipitation of metallic Pd. The presence of the longest aliphatic group in the Pd@NHCs-sugar UNPs imparts to them the highest catalyst activity (turnover number and turnover frequency up to 196?000 and 3?920?000?h?1).
- Zhou, Zhonggao,Li, Mei,Liu, Guangsheng,Xu, Guohai,Xue, Jun
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- Agro-Waste Generated Pd/CAP-Ash Catalyzed Ligand-Free Approach for Suzuki–Miyaura Coupling Reaction
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Abstract: We converted agro-waste Custard Apple Peels (CAP) to ash via thermal treatment, on which Pd(OAc)2 was immobilized easily that produced a low-cost, highly efficient Pd/CAP-ash catalyst. The prepared catalyst was fully characterized by using FT-IR, SEM, EDX, XRF, DSC-TGA, BET, HR-TEM, and XPS techniques. The Pd/CAP-ash catalyst was conveniently applied for the Suzuki–Miyaura coupling reaction under external base free and ligand-free conditions in an aqueous-organic solvent to produce biphenyls in good to excellent yields. The main attraction of our protocol an application of palladium-supported agro-waste material which is easily recoverable and recyclable provides mono and bis-coupled derivatives in a short reaction time. Graphic Abstract: [Figure not available: see fulltext.].
- Patil, Rupesh C.,Jagdale, Ashutosh A.,Patil, Uttam P.,Ghodake, Jeevan S.,Mali, Sawanta S.,Hong, Chang K.,Patil, Suresh S.
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supporting information
p. 3617 - 3631
(2021/04/02)
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- From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
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The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
- De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
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p. 133 - 147
(2021/05/10)
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- Green, Efficient and Reusable Bis(imidazolium) Ionic Liquids Promoted Pd-Catalyzed Aqueous Suzuki Reaction for Organic Functional Materials
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Abstract: Glucopyranoside-substituted asymmetric bis(imidazolium) ionic liquids were used to promote environmentally friendly, efficient and reusable Pd-catalyzed Suzuki reaction between arylboronic acids and 2-bromofluorene, 2,7-dibromo-9,9′-dialkylfluorene. Over 30 carbazole-based fluorene core potential organic functional materials were synthesized. In addition, recyclability of catalyst system was inspected on the Suzuki reaction observing nearly no loss in catalytic activity up to five cycles. Graphical Abstract: Development of green, efficient and recycle glucopyranoside substituted bis(imidazolium) ILs promoted Pd-catalyzed aqueous Suzuki reaction for OFMs. [Figure not available: see fulltext.].
- Zhou, Zhonggao,Yuan, Yangyang,Xie, Yongrong,Li, Mei
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p. 2696 - 2702
(2018/07/13)
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- Condensed cyclic compound and organic light-emitting device comprising the same
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Disclosed are a condensed cyclic compound displayed as chemical formula 1, and an organic light emitting device having the same. The organic light emitting device including the condensed cyclic compound has high brightness, high efficiency, and excellent durability.COPYRIGHT KIPO 2018
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Paragraph 0585; 0587; 0588
(2018/05/03)
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- Spirobifluorene Regioisomerism: A Structure–Property Relationship Study
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The present works report the first structure–property relationship study of a key class of organic semiconductors, that is, the four spirobifluorene positional isomers possessing a para-, meta- or ortho-linkage. The remarkable and surprising impact of the ring bridging and of the linkages on the electronic properties of the regioisomers has been particularly highlighted and rationalised. The impact of the ring bridging on the photophysical properties has been stressed with notably the different influence of the linkages and the bridge on the singlet and triplet excited states. The first member of a new family of spirobifluorenes substituted in the 1-position, which presents better performance in blue phosphorescent OLEDs than those of its regioisomers, is reported. These features highlight not only the great potential of 1-substituted spirobifluorenes, but also the remarkable impact of regioisomerism on electronic properties.
- Sicard, Lambert,Quinton, Cassandre,Peltier, Jean-David,Tondelier, Denis,Geffroy, Bernard,Biapo, Urelle,Métivier, Rémi,Jeannin, Olivier,Rault-Berthelot, Jo?lle,Poriel, Cyril
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supporting information
p. 7719 - 7727
(2017/06/06)
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- Synthesis of Fluorenes Starting from 2-Iodobiphenyls and CH2Br2 through Palladium-Catalyzed Dual C-C Bond Formation
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A facile and efficient approach is developed for the synthesis of fluorene and its derivatives starting from 2-iodobiphenyls and CH2Br2. A range of fluorene derivatives can be synthesized under relatively mild conditions. The reaction proceeds via a tandem palladium-catalyzed dual C-C bond formation sequence through the key dibenzopalladacyclopentadiene intermediates, which are obtained from 2-iodobiphenyls through palladium-catalyzed C-H activation.
- Shi, Guangfa,Chen, Dushen,Jiang, Hang,Zhang, Yu,Zhang, Yanghui
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p. 2958 - 2961
(2016/07/06)
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- Palladium supported on silica-chitosan hybrid material (Pd-CS@SiO2) for Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions
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Palladium supported on silica-chitosan hybrid material was prepared and characterized using thermogravimetric and differential thermogravimetric analyses, scanning electron microscopy, and Fourier transform infrared, energy-dispersive X-ray and X-ray photoelectron spectroscopies. The prepared Pd-CS@SiO2 catalyst (1 mol%) was used for the Suzuki-Miyaura cross-coupling reaction of various aryl halides and arylboronic acids in 95% ethanol at 80 °C and the Mizoroki-Heck reaction in dimethylformamide at 110 °C using K2CO3 as a base. The developed catalyst is well suitable for the 3R approach (recoverable, robust, recyclable) for cross-coupling reactions without appreciable loss of its activity.
- Jadhav, Sanjay,Kumbhar, Arjun,Salunkhe, Rajashri
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p. 339 - 345
(2015/06/02)
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- Gold(I) carbenes by retro-buchner reaction: Generation and fate
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The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon-carbon cleavages occur on a rather flat potential energy surface.
- Wang, Yahui,McGonigal, Paul R.,Herle, Bart,Besora, Maria,Echavarren, Antonio M.
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supporting information
p. 801 - 809
(2014/02/14)
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- Vasicine catalyzed direct C-H arylation of unactivated arenes: Organocatalytic application of an abundant alkaloid
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Vasicine, a quinazoline alkaloid isolated from Adhatoda vasica, has been employed as an organocatalyst for direct C-H arylation of unactivated arenes with aryl iodides/bromides without the assistance of any transition metal catalyst. A number of sensitive functional groups such as methyl, methoxy, O-benzyl, acetyl, and amino were well tolerated under present reaction conditions. Mechanistic investigation supported the involvement of radical intermediates.
- Sharma, Sushila,Kumar, Manoranjan,Kumar, Vishal,Kumar, Neeraj
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supporting information
p. 4868 - 4871
(2013/08/28)
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- Gel-entrapped bases: A smart window for the ligand-free Suzuki-Miyaura cross-coupling reaction
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A gel-entrapped base has been fabricated by using agarose (biopolymer), and tested in the Suzuki-Miyaura cross-coupling reaction in 95% ethanol. The developed environmentally benign polymer-supported base has low leaching and high stability for the Suzuki-Miyaura cross-coupling reaction to give high yield with green credit.
- Jadhav, Sanjay,Kumbhar, Arjun,Kamble, Santosh,More, Pallavi,Salunkhe, Rajashri
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p. 957 - 961
(2013/11/06)
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- Palladium supported hybrid cellulose-aluminum oxide composite for Suzuki-Miyaura cross coupling reaction
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A cellulose-aluminum oxide composite was prepared and modified with organo-functional groups by reacting with the coupling reagent (CH 3O)3Si(CH2)3NH2 through Al-O-Si bonds. The amino groups confined in the composite were found to be efficient for palladium entrapment, leading to a highly active and reusable heterogeneous catalyst (Pd@Al2O3-CELL) for Suzuki-Miyaura cross coupling reaction in water and H2O/DMF (8:2) mixture at 80 °C. Copyright
- Kumbhar, Arjun,Jadhav, Sanjay,Kamble, Santosh,Rashinkar, Gajanan,Salunkhe, Rajashri
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p. 1331 - 1337
(2013/05/08)
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- Silica tethered Pd-DABCO complex: An efficient and reusable catalyst for suzuki-miyaura reaction
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A palladium-based catalyst supported on DABCO-functionalized silica was successfully prepared by a facile procedure. The prepared heterogeneous catalyst showed a high activity for the Suzuki-Miyaura reaction of aryl bromides, affording excellent yield in all the cases investigated. Interestingly, the catalyst could be quantitatively recovered from the reaction mixture and recycled for five times without any significant loss in activity. Furthermore, this protocol could be extended to the palladium catalyzed synthesis of annulated pyrazines. Springer Science+Business Media, LLC 2012.
- Kumbhar, Arjun,Kamble, Santosh,Jadhav, Sanjay,Rashinkar, Gajanan,Salunkhe, Rajashri
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p. 1388 - 1396
(2013/01/15)
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- Fast Suzuki-Miyaura cross-coupling reaction catalyzed by the Na 2Pd2Cl6 complex with ethyl calix[4]aryl acetate at room temperature in aqueous medium under ligand-free and ambient atmosphere
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The new Na2Pd2Cl6 complex with ethyl calix[4]aryl acetate 2 was prepared simply and efficiently by the extraction of sodium ion from Na2PdCl4 aqueous solution with ethyl calix[4]aryl acetate. The structure of complex 2 could be verified by X-ray single crystal structure determination. The complex 2 was tested as catalyst in Suzuki-Miyaura cross-coupling reaction at room temperature in CH 3OH/H2O medium under ambient conditions. Using 0.2 mol% of the complex 2 in the presence of K2CO3 as base offered excellent yields in the reaction of activated and non-activated aryl bromides with aryl boronic acids within 10 min. The key for achieving a very rapid and almost quantitative coupling is probably the use of ethyl calix[4]aryl acetate possessing extended hydrophobic host cavities and surface active properties. In addition, it was found that both solvent and base had a fundamental influence on the reaction.
- Mu, Bing,Li, Jingya,Han, Zixing,Wu, Yangjie
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experimental part
p. 117 - 124
(2012/03/13)
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- The highly efficient Suzuki-Miyaura cross-coupling reaction using cyclopalladated N-alkylferrocenylimine as a catalyst in aqueous medium at room temperature under ambient atmosphere
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A series of N-alkyl-substituted cyclopalladated ferrocenylimines were used in palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl halides in room temperature and CH3OH/H2O media under aerobic conditions. As for the ca
- Mu, Bing,Li, Tiesheng,Li, Jingya,Wu, Yangjie
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p. 1243 - 1251
(2008/09/17)
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Seventeen new catalyst precursors for the syndiospecific polymerization of propylene are presented. The new metallocene complexes are substituted in the positions 2 and 7 of the fluorenylidene fragment by MeO-, halogen-, alkyl-and aryl groups. The focus i
- Alt, Helmut G.,Zenk, Roland
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