Templated Synthesis of Interlocked Molecules

Aricò, Fabio; Badjić, Jovica D.; Cantrill, Stuart; Flood, Amar H.; Leung, Ken Cham‐Fai; Liu, Yi; Stoddart, J. Fraser

doi:10.1007/b104330

Cited by 195 publications

(67 citation statements)

References 176 publications

(351 reference statements)

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“…34 Since only one set of 1 H NMR resonances was observed for the axles at room temperature, it was concluded that the DB24C8 molecules were undergoing fast exchange between the two binding sites. From VT-NMR spectral data it was determined that the rate of exchange between the two sites was on the order of 200-300 Hz.…”

Section: Molecular Shuttlesmentioning

confidence: 99%

Rotaxanes as ligands: from molecules to materials

2007

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This tutorial review documents the discovery and application of the supramolecular template (1,2-bis(pyridinium)ethane) subset (24-crown-8) for preparing interlocked molecules. Focus is on the supramolecular chemistry of the pseudorotaxanes formed with various pyridinium axles and crown ether wheels and how this particular class of mechanically linked molecule has been (i) used to construct rudimentary molecular machines such as molecular shuttles and flip switches, (ii) used as ligands for coordination chemistry and (iii) used to create metal-organic framework (MORF) materials.

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Section: Molecular Shuttlesmentioning

confidence: 99%

Rotaxanes as ligands: from molecules to materials

2007

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“…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)(31)(32)(33)(34)(35)(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.…”

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confidence: 99%

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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“…This study showed that the approach is extremely sensitive to small changes in the structure of the macrocycle and dumbbell -shaped components, which, in turn, have dramatic effects on the kinetics and thermodynamics of the assemblies. Furan -containing macrocycles derived from dialdehyde 87 and π -electron -defi cient dumbbell -shaped ions (like 89 ) are the components of choice to form the thermodynamically most -stable [2]rotaxanes, although pyridine containing macrocycles form [2]rotaxanes that are more kinetically stable [145] .…”

Section: Synthetic Receptors For Organic Guestsmentioning

confidence: 99%

Development of Synthetic Receptors using Dynamic Combinatorial Chemistry

Escalante

Furlán

2010

Dynamic Combinatorial Chemistry

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In order to bind a given guest, a receptor must be complementary -it must have recognition groups which are of the appropriate electronic character to complement the binding sites of the guest. Those recognition groups must be positioned on the receptor in a way that they can interact with recognition groups from the guest when both receptor and guest are in the binding conformation. Upon binding, the receptor and guest reorganize their interactions with solvent molecules (disrupting some and probably creating new ones), and change their conformation to achieve a suitable binding conformation. In the process, noncovalent interactions within each molecule may be broken or formed.The requirement to balance all the variables involved in this recognition process makes the design of successful synthetic receptors a signifi cant challenge.A frequently explored shortcut that facilitates receptor design is to incorporate rigidity in order to avoid as much as possible changes in conformation that are diffi cult to predict. In addition, a rigid preorganized receptor will decrease the cost of unfavorable reorganization energy. However, high -affi nity perfectly rigid receptors are not easy to achieve in practice since minor errors in design that demand readjustment from the receptor can be energetically very expensive [1] . Indeed, nature does not use rigidity to improve affi nity, but it still produces receptors with affi nities that are on average much better than the best synthetic receptors prepared to date. A recent survey of the binding effi ciency of synthetic and biological hosts by Houk et al. indicates that synthetic systems are typically several orders of magnitude less effi cient in binding small molecules than their biological counterparts [2] .Guest binding by natural receptors such as proteins is reinforced by intrareceptor interactions, which require conformational rearrangements of parts of the receptor that are very similar to the conformational rearrangement necessary to interact with the guest. Consequently the interactions that contribute to guest binding extend beyond the immediate binding site well into the protein structure [3] . Synthetic receptors that operate by the same principle will need to be able to Dynamic Combinatorial Chemistry. Edited by Joost N. H. Reek and Sijbren Otto

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Templated Synthesis of Interlocked Molecules

Cited by 195 publications

References 176 publications

Rotaxanes as ligands: from molecules to materials

Rotaxanes as ligands: from molecules to materials

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

Development of Synthetic Receptors using Dynamic Combinatorial Chemistry

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