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Highly Efficient Supramolecular Catalysis by Endowing the Reaction Intermediate with Adaptive Reactivity 下载免费PDF全文
Yang Jiao Bohan Tang Yucheng Zhang Dr. Jiang‐Fei Xu Prof. Zhiqiang Wang Prof. Xi Zhang 《Angewandte Chemie (International ed. in English)》2018,57(21):6077-6081
A new strategy of highly efficient supramolecular catalysis is developed by endowing the reaction intermediate with adaptive reactivity. The supramolecular catalyst, prepared by host–guest complexation between 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO) and cucurbit[7]uril (CB[7]), was used for biphasic oxidation of alcohols. Cationic TEMPO+, the key intermediate, was stabilized by the electrostatic effect of CB[7] in aqueous phase, thus promoting the formation of TEMPO+ and inhibiting side reactions. Moreover, through the migration into the organic phase, TEMPO+ was separated from CB[7] and recovered the high reactivity to drive a fast oxidation of substrates. The adaptive reactivity of TEMPO+ induced an integral optimization of the catalytic cycle and greatly improved the conversion of the reaction. This work highlights the unique advantages of dynamic noncovalent interactions on modulating the activity of reaction intermediates, which may open new horizons for supramolecular catalysis. 相似文献
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Peter T. Smith Younghoon Kim Bahiru Punja Benke Kimoon Kim Christopher J. Chang 《Angewandte Chemie (International ed. in English)》2020,59(12):4902-4907
We report a supramolecular strategy for promoting the selective reduction of O2 for direct electrosynthesis of H2O2. We utilized cobalt tetraphenylporphyrin (Co‐TPP), an oxygen reduction reaction (ORR) catalyst with highly variable product selectivity, as a building block to assemble the permanently porous supramolecular cage Co‐PB‐1(6) bearing six Co‐TPP subunits connected through twenty‐four imine bonds. Reduction of these imine linkers to amines yields the more flexible cage Co‐rPB‐1(6). Both Co‐PB‐1(6) and Co‐rPB‐1(6) cages produce 90–100 % H2O2 from electrochemical ORR catalysis in neutral pH water, whereas the Co‐TPP monomer gives a 50 % mixture of H2O2 and H2O. Bimolecular pathways have been implicated in facilitating H2O formation, therefore, we attribute this high H2O2 selectivity to site isolation of the discrete molecular units in each supramolecule. The ability to control reaction selectivity in supramolecular structures beyond traditional host–guest interactions offers new opportunities for designing such architectures for a broader range of catalytic applications. 相似文献
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Pierre‐Alain R. Breuil Frederic W. Patureau Joost N. H. Reek Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(12):2162-2165
H bonds make the catalysts! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalysts for asymmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the heterocomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates.
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Anne C. H. Jans Dr. Adrián Gómez‐Suárez Prof. Dr. Steven P. Nolan Prof. Dr. Joost N. H. Reek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):14836-14839
Dinuclear gold complexes have the ability to interact with one or more substrates in a dual‐activation mode, leading to different reactivity and selectivity than their mononuclear relatives. In this contribution, this difference was used to control the catalytic properties of a gold‐based catalytic system by site‐isolation of mononuclear gold complexes by selective encapsulation. The typical dual‐activation mode is prohibited by this catalyst encapsulation, leading to typical behavior as a result of mononuclear activation. This strategy can be used as a switch (on/off) for a catalytic reaction and also permits reversible control over the product distribution during the course of a reaction. 相似文献
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Hans‐Jrg Schneider 《Angewandte Chemie (International ed. in English)》2009,48(22):3924-3977
Forces to reckon with : Supramolecular complexes, such as the one shown, are normally based on a combination of different interactions such as ion pairing, hydrogen bonds, and stacking interactions. The not always simple characterization of the nature and strength of intermolecular forces provides assistance to the understanding of biomimetic systems, as well as for the design of synthetic receptors, drugs, and intelligent materials.
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A photolytically generated ruthenium hydride species catalyzing a free radical cyclization reaction was developed. As the new methodology ensures reproducibility of the free radical reaction of trialkyltin hydrides and a fast hydrogen transfer to the radical intermediates, the methodology provides fast quenching of radical intermediates and thus suppresses rearrangement of radical intermediates before the hydride quench. By offering new reactivity and selectivity to the trialkyltin hydride mediated free radical cyclization reactions, the methodology will find wide range of applications in organic synthesis. 相似文献
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Marx VM Stoddard RL Heverly-Coulson GS Burnell DJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(29):8098-8104
Alkyl substitution α to the ketone of an allenyl vinyl ketone enhances Nazarov reactivity by inhibiting alternative pathways involving the allene moiety and through electron donation and/or steric hindrance. This substitution pattern also accelerates Nazarov cyclisation by increasing the population of the reactive conformer and by stabilising the oxyallyl cation intermediate. Furthermore, α substitution by an alkyl group does not alter the regioselectivity of interrupted Nazarov reactions when the oxyallyl cation intermediate is intercepted by addition of an oxygen nucleophile, or by [4+3] cyclisation with acyclic dienes. The regioselectivity of the Nazarov process for allenyl vinyl ketones was determined to be a result of an electronic bias in the oxyallyl cation intermediate. Computational data are consistent with this observation. 相似文献
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Dr. Paolo Zardi Dr. Thierry Roisnel Dr. Rafael Gramage-Doria 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):627-634
Inspired by enzymes such as cytochrome P-450, the study of the reactivity of metalloporphyrins continues to attract major interest in the field of homogeneous catalysis. However, little is known about benefitting from the substrate-recognition properties of porphyrins containing additional, catalytically relevant active sites. Herein, such an approach is introduced by using supramolecular ligands derived from metalloporphyrins customized with rigid, palladium-coordinating nitrile groups. According to different studies (NMR and UV/Vis spectroscopy, XRD, control experiments), the supramolecular ligands are able to accommodate pyridine derivatives as substrates inside the porphyrin pocket while the reactivity occurs at the peripheral side. By simply tuning a remote metal center, different binding events result in different catalyst reactivity, and this enzyme-like feature leads to high degrees of substrate selectivity in representative palladium-catalyzed Suzuki–Miyaura reactions. 相似文献
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Maarten M. J. Smulders Marko M. L. Nieuwenhuizen Tom F. A. de Greef Dr. Paul van der Schoot Prof. Dr. Albertus P. H. J. Schenning Dr. E. W. Meijer Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(1):362-367
To study the supramolecular polymerisation mechanisms of a self‐assembling system, concentration‐ and temperature‐dependent measurements can both be used to probe the transition from the molecular dissolved state to the aggregated state. In this report, both methods are evaluated to determine their effectiveness in identifying and quantifying the self‐assembly mechanism for isodesmic and cooperative self‐assembling systems. It was found that for a rapid and unambiguous determination of the self‐assembly mechanism and its thermodynamic parameters, temperature‐dependent measurements are more appropriate. These studies allow the acquisition of a large data set leading to an accurate determination of the self‐assembly mechanism and quantification of the different thermodynamic parameters that describe the supramolecular polymerisation. For a comprehensive characterisation, additional concentration‐dependent measurements can be performed. 相似文献
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Dr. Jean‐Nicolas Desrosiers Liana Hie Dr. Soumik Biswas Dr. Olga V. Zatolochnaya Dr. Sonia Rodriguez Dr. Heewon Lee Dr. Nelu Grinberg Dr. Nizar Haddad Dr. Nathan K. Yee Prof. Neil K. Garg Dr. Chris H. Senanayake 《Angewandte Chemie (International ed. in English)》2016,55(39):11921-11924
A nickel‐catalyzed Heck cyclization for the construction of quaternary stereocenters is reported. This transformation is demonstrated in the synthesis of 3,3‐disubstituted oxindoles, which are prevalent motifs seen in numerous biologically active molecules. The method shows broad scope, proceeds in synthetically useful yields, and provides a rare means to construct stereochemically complex frameworks by nonprecious‐metal catalysis. 相似文献
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Dr. Weiwei Fang Yang Zhang Jiajie Wu Cong Liu Dr. Haibo Zhu Prof. Dr. Tao Tu 《化学:亚洲杂志》2018,13(7):712-729
Over the past two decades, supramolecular gels have attracted significant attention from scientists in diverse research fields and have been extensively developed. This review mainly focuses on the significant achievements in supramolecular gels and catalysis. First, by incorporating diverse catalytic sites and active organic functional groups into gelator molecules, supramolecular gels have been considered as a novel matrix for catalysis. In addition, these rationally designed supramolecular gels also provide a variety of templates to access metal nanocomposites, which may function as catalysts and exhibit high activity in diverse catalytic transformations. Finally, as a new kind of biomaterial, supramolecular gels formed in situ by self‐assembly triggered by catalytic transformations are also covered herein. 相似文献
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Callum R. Woof Derek J. Durand Dr. Natalie Fey Dr. Emma Richards Dr. Ruth L. Webster 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):5972-5977
Iron-catalyzed isomerization of alkenes is reported using an iron(II) β-diketiminate pre-catalyst. The reaction proceeds with a catalytic amount of a hydride source, such as pinacol borane (HBpin) or ammonia borane (H3N⋅BH3). Reactivity with both allyl arenes and aliphatic alkenes has been studied. The catalytic mechanism was investigated by a variety of means, including deuteration studies, Density Functional Theory (DFT) and Electron Paramagnetic Resonance (EPR) spectroscopy. The data obtained support a pre-catalyst activation step that gives access to an η2-coordinated alkene FeI complex, followed by oxidative addition of the alkene to give an FeIII intermediate, which then undergoes reductive elimination to allow release of the isomerization product. 相似文献
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Dr. Dariusz G. Piekarski Pascal Steinforth Dr. Melania Gómez-Martínez Dr. Julia Bamberger Florian Ostler Prof. Dr. Monika Schönhoff Prof. Dr. Olga García Mancheño 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17598-17603
H-bond donor catalysts able to modulate the reactivity of ionic substrates for asymmetric reactions have gained great attention in the past years, leading to the development of cooperative multidentate H-bonding supramolecular structures. However, there is still a lack of understanding of the forces driving the ion recognition and catalytic performance of these systems. Herein, insight into the cooperativity nature, anion binding strength, and folding mechanism of a model chiral triazole catalyst is presented. Our combined experimental and computational study revealed that multi-interaction catalysts exhibiting weak binding energies (≈3–4 kcal mol−1) can effectively recognize ionic substrates and induce chirality, while strong dependencies on the temperature and solvent were quantified. These results are key for the future design of catalysts with optimal anion binding strength and catalytic activity in target reactions. 相似文献
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Laungani AC Slattery JM Krossing I Breit B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(15):4488-4502
The principles of protein structure design, molecular recognition, and supramolecular and combinatorial chemistry have been applied to develop a convergent metal-ion-assisted self-assembly approach that is a very simple and effective method for the de novo design and the construction of topologically predetermined antiparallel beta-sheet structures and self-assembled catalysts. A new concept of in situ generation of bidentate P-ligands for transition-metal catalysis, in which two complementary, monodentate, peptide-based ligands are brought together by employing peptide secondary structure motif as constructing tool to direct the self-assembly process, is achieved through formation of stable beta-sheet motifs and subsequent control of selectivity. The supramolecular structures were studied by (1)H, (31)P, and (13)C NMR spectroscopy, ESI mass spectrometry, X-ray structure analysis, and theoretical calculations. Our initial catalysis results confirm the close relationship between the self-assembled sheet conformations and the catalytic activity of these metallopeptides in the asymmetric rhodium-catalyzed hydroformylation. Good catalyst activity and moderate enantioselectivity were observed for the selected combination of catalyst and substrate, but most importantly the concept of this new methodology was successfully proven. This work presents a perspective interface between protein design and supramolecular catalysis for the design of beta-sheet mimetics and screening of libraries of self-organizing supramolecular catalysts. 相似文献