Suitanes

Williams, Avril; Northrop, Brian H.; Chang, Tsuen; Stoddart, J. Fraser; White, Andrew J. P.; Williams, David J.

doi:10.1002/anie.200602173

Cited by 92 publications

(43 citation statements)

References 55 publications

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“…7B) in the reliable mass/charge range (500-2,500) of the instrument (see SI Fig. 12e), once again supporting the formation of the [11]rotaxane.…”

Section: Resultssupporting

confidence: 58%

“…A golden-yellow solution was obtained within a few minutes after mixing the components and the 1 H NMR spectrum shows (Fig. 7) clearly that the major species present in the CD 3 NO 2 solution is the desired [11]rotaxane. It is similar to that of the [7]rotaxane prepared under similar conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The formation of the [11]rotaxane (a 21-component selfassembly) and the [15]rotaxane (a 29-component self-assembly) using similar clipping protocols, however, encountered practical problems associated, most likely, with the extremely poor solubilities of the dumbbell templates in MeNO 2 , conferring low solubilities on the rotaxanes as well. Specifically, the clipping reaction for the formation of the [11]rotaxane was performed under moderately dilute conditions, for example, 2.5 mg of the dumbbell in 10 ml of CD 3 NO 2 , wherein the mixture became nearly clear within 2 h. 1 H NMR spectra and HR-ESI-MS (not shown) revealed partial formation of the desired [11]rotaxane with other products dominating the reaction mixture.…”

Section: Resultsmentioning

confidence: 99%

“…Specifically, the clipping reaction for the formation of the [11]rotaxane was performed under moderately dilute conditions, for example, 2.5 mg of the dumbbell in 10 ml of CD 3 NO 2 , wherein the mixture became nearly clear within 2 h. 1 H NMR spectra and HR-ESI-MS (not shown) revealed partial formation of the desired [11]rotaxane with other products dominating the reaction mixture. Changing the solvent to CD 3 CN did not enhance the formation of the desired [11]rotaxane. The situation surrounding the formation of the [15]rotaxane was even more discouraging insofar as the suspension in the reaction did not become clear even under highly dilute conditions and with stirring at room temperature for several days.…”

Section: Resultsmentioning

confidence: 99%

“…M echanically interlocked and knotted compounds, such as rotaxanes (1)(2)(3)(4)(5), catenanes (6-10), suitanes (11,12), trefoil knots (13)(14)(15)(16)(17), Borromean rings (18)(19)(20), and Solomon knots (21), represent challenging synthetic goals that have nevertheless been realized. These molecular compounds are usually synthesized by a template-directed approach (22) that depends on molecular recognition and self-assembly processes.…”

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confidence: 99%

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Efficient production of [ n ]rotaxanes by using template-directed clipping reactions

Leung

Stoddart

2007

Proc. Natl. Acad. Sci. U.S.A.

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119

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In this article, we report on the efficient synthesis of well defined, homogeneous [n]rotaxanes (n up to 11) by a template-directed thermodynamic clipping approach. By employing dynamic covalent chemistry in the form of reversible imine bond formation, [ dynamic covalent chemistry ͉ molecular recognition ͉ polyrotaxanes ͉ self-assembly ͉ template-directed synthesis M echanically interlocked and knotted compounds, such as rotaxanes (1-5), catenanes (6-10), suitanes (11, 12), trefoil knots (13-17), , and Solomon knots (21), represent challenging synthetic goals that have nevertheless been realized. These molecular compounds are usually synthesized by a template-directed approach (22) that depends on molecular recognition and self-assembly processes. Recently, their potential applications as molecular switches for nanoelectronics (23, 24) and molecular actuators for constructing artificial muscles (25), for fabricating smart surface materials (26), and for controlling the nanoscale release of molecules trapped in mesoporous silica (27)(28)(29) were demonstrated. Polyrotaxanes and well defined, homogeneous oligorotaxanes, in which the recognition sites on a dumbbell (an axle terminated by bulky stoppers) are encircled by large rings or macrocycles (wheels) by dint of molecular recognition, have become (30-36) one of the most intensively investigated subjects in mechanical chemistry. A general synthetic method for making rotaxanes, namely, the ''threading-followed-by-stoppering'' approach (Fig. 1, method A), involves (30-32) several macrocycles. First, the macrocycles are threaded onto oligomeric or polymeric axles carrying recognition sites at prescribed intervals along the axles to form pseudorotaxanes, then both ends of the axles are stoppered with bulky groups. Although this approach is relatively simple, it does not provide complete control over the number of threaded macrocycles, that is, the rings or beads are often not threaded onto all of the available recognition sites on the axles. Alternatively, a template-directed ''clipping'' approach (Fig. 1, method B), in which the macrocycles are formed from acyclic precursors in the presence of templating recognition sites on the dumbbells, has provided (33-36) a versatile means for the construction of some lower-order rotaxanes. Nonetheless, the efficient synthesis of well defined, homogeneous, higher-order polyrotaxanes continues to be a challenge to synthetic chemists.Recently, dynamic covalent chemistry (37-40), exemplified by reversible imine formation (41, 42), metal-ligand exchange (43), and olefin metathesis (44, 45), has been demonstrated to be an effective tool for the preparation of various exotic mechanically interlocked molecular compounds. It has been found that, in the presence of an appropriate template, one of the possible compounds in the dynamic library, after mixing the different components, can be amplified to give the thermodynamically most stable product. We have reported (see refs. 46-49) an example of such a template-directed synthesis of ...

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“…7B) in the reliable mass/charge range (500-2,500) of the instrument (see SI Fig. 12e), once again supporting the formation of the [11]rotaxane.…”

Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Efficient production of [ n ]rotaxanes by using template-directed clipping reactions

Leung

Stoddart

2007

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

119

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Dynamic Covalent Chemistry

Gasparini¹,

Molin²,

Lovato³

et al. 2012

Supramolecular Chemistry

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Dynamic covalent chemistry forms the key ingredient for a new approach toward organic synthesis. Dynamic covalent chemistry regards the synthesis of covalent organic molecules under thermodynamic control. It relies on the use of covalent bonds that can be reversibly formed under the experimental conditions. It combines the advantages typically associated with noncovalent synthesis (the formation of molecular structures using noncovalent interactions), such as spontaneous formation, error correction, and proof reading, with the robustness of covalent bonds. For many covalent bonds, experimental conditions under which the reaction occurs reversibly are known, but the majority of systems relies on trans(thio)esterifications and disulfide or imine‐type exchange reactions. These reactions occur rapidly under mild conditions, use readily accessible building blocks, and can be turned off to obtain kinetically inert products. It is illustrated that dynamic covalent chemistry gives a rapid access toward organic structures of nanometer dimensions. Typically, a one‐step, one‐pot synthetic protocol is used, which in some cases also involves multiple dynamic covalent bonds in an orthogonal manner. The fundamental difference with covalent synthesis is that equilibrium reactions are used. This introduces a characteristic property, which is the possibility of the chemical system to adapt to changes in its environment according to Le Châtelier's principle. This concept is referred to as dynamic combinatorial chemistry ( DCC ) and has been successfully applied for the preparation of new receptors, guests, sensors, materials, and so forth. Examples, together with the potential and limitations of this approach, are discussed. The final section is dedicated to the systems in which dynamic covalent bonds provide structural stability but intramolecular noncovalent interactions determine the composition of the resulting equilibrium. It is shown that this approach, that is, dynamic covalent capture, is a very sensitive tool for the quantification of weak interactions, for instance, in protein folding or catalysis.

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Other Supramolecular Systems, Molecular Motors, Machines and Nanotechnological Applications

Davis

Higson

2011

Macrocycles

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Suitanes

Cited by 92 publications

References 55 publications

Efficient production of [ n ]rotaxanes by using template-directed clipping reactions

Efficient production of [ n ]rotaxanes by using template-directed clipping reactions

Dynamic Covalent Chemistry

Other Supramolecular Systems, Molecular Motors, Machines and Nanotechnological Applications

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