Molecular Knots

Dietrich‐Buchecker, Christiane; Colasson, Benoît X.; Sauvage, Jean‐Pierre

doi:10.1007/b104331

Cited by 97 publications

(29 citation statements)

References 56 publications

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“…These compounds have generally been prepared in an efficient way from several precursor fragments [23]. As already mentioned, among the most spectacular examples of topologically novel synthetic molecules, molecular knots, such as the trefoil knot [24] or its derivatives [25], as well as the Borromean rings [1], are particularly representative. Even if rotaxanes are not, strictly speaking, topologically significant compounds due the planarity of their molecular graphs, rotaxanes have often been considered as topologically non-trivial due to their analogy to catenanes [26], at least in terms of synthetic approaches.…”

Section: Rotaxane Synthesismentioning

confidence: 99%

The magic effect of endocyclic but non-sterically hindering biisoquinoline chelates: From fast-moving molecular shuttles to [3]rotaxanes

Durola

Sauvage

Wenger

2010

Coordination Chemistry Reviews

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Section: Rotaxane Synthesismentioning

confidence: 99%

The magic effect of endocyclic but non-sterically hindering biisoquinoline chelates: From fast-moving molecular shuttles to [3]rotaxanes

Durola

Sauvage

Wenger

2010

Coordination Chemistry Reviews

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“…[34,36] The first method is based on the template effect of a transition metal, [38,41,42] which gathers and disposes the molecular fragments in a predetermined geometry. They have been studied in many scientific fields, from mathematics to chemistry.…”

Section: Methodsmentioning

confidence: 99%

Imaging of Catenated, Figure‐of‐Eight, and Trefoil Knot Polymer Rings

Schappacher

Deffieux

2009

Angewandte Chemie

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Most of the available characterization techniques for macromolecules are based on the determination of the average properties (chemical composition, tacticity, dimensional parameters, melting temperature, etc) of an entire set of molecules in a given system. In this context, imaging techniques could offer a quite different and unique approach that allows the analysis of macromolecules as single objects. However, isolated polymer chains are often too diffuse to be distinctly and directly visualized. To circumvent this problem, a magnification process of the size and density of macromolecules prior to imaging can be used to homogeneously enlarge isolated polymer chains before observation by atomic force microscopy (AFM). Numerous studies have been devoted over the past decades to the investigation of the properties of isolated biomolecules by molecular imaging. The visualization of single DNA molecules [1] has shown that DNA can exist in the form of single and interlocked rings of various complexities. [1,4] Since then, several examples of catenated and knotted single-and double-stranded DNA rings have been reported. [5][6][7][8][9] Continuous progress in this area is clearly associated with the development of imaging techniques that allow the investigation of the molecular structure [10,11] and mechanical properties [12][13][14][15] of isolated macromolecules. Besides biomacromolecules, a limited number of reports have addressed the imaging of isolated polyelectrolyte chains, [16][17][18] and even fewer studies of the AFM investigation of neutral polymer chains at the molecular level have been reported. [19,20] Indeed, neutral linear polymer chains, which have sizes that range from a few to several hundred nanometers, possess a cross section of only a few atoms and are softer than biomolecules and polyelectrolytes. Moreover, their local concentration can widely fluctuate through chain motion because of weaker interactions with substrates. [21][22][23] This fluctuation makes the linear polymer chains highly diffuse objects that cannot be easily observed by imaging microscopy. To increase the contrast of the images, selective adsorption of salts has been used by Minko and co-workers in the case of polyelectrolyte chains. [24] To date, AFM visualization and characterization of single synthetic non-ionic macromolecules has been mostly limited to macromolecules with invariant shape such as carbon nanotubes, comb polymers, [25][26][27][28][29][30][31] and dendrigrafts, [32,33] which possess higher mass densities along their backbone than linear polymers. Therefore, one method to permit molecular imaging of single linear, cyclic, and starlike main-chain polymers could involve magnification of the macromolecules by homogeneously increasing their mass density along the whole of the chain, thus making their cross-section thicker and more readily detectable by the AFM tip. This magnification can be achieved, for example, by uniform grafting of well-defined oligomers onto the backbone of the target macromolecules, a strategy ...

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“…Taking this approach even further, the cyclization of a related tricopper(I) double helicate formed from extended phenanthroline ligands allowed access to a molecular Solomon Link (Nierengarten et al 1994), and the cyclization of helical complexes has proved to be a successful methodology in preparing molecular knots and links. A series of Trefoil knots have also been prepared (Lukin & Vögtle 2005) by serendipitous neutral hydrogenbond templation, while metal cations have also adopted a significant role in the preparation of topologically non-trivial knots and links (Dietrich-Buchecker et al 2005).…”

Section: Chemical Topologymentioning

confidence: 99%

Mechanostereochemistry and the mechanical bond

2012

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The chemistry of mechanically interlocked molecules (MIMs), in which two or more covalently linked components are held together by mechanical bonds, has led to the coining of the term mechanostereochemistry to describe a new field of chemistry that embraces many aspects of MIMs, including their syntheses, properties, topologies where relevant and functions where operative. During the rapid development and emergence of the field, the synthesis of MIMs has witnessed the forsaking of the early and grossly inefficient statistical approaches for template-directed protocols, aided and abetted by molecular recognition processes and the tenets of self-assembly. The resounding success of these synthetic protocols, based on templation, has facilitated the design and construction of artificial molecular switches and machines, resulting more and more in the creation of integrated functional systems. This review highlights (i) the range of template-directed synthetic methods being used currently in the preparation of MIMs; (ii) the syntheses of topologically complex knots and links in the form of stable molecular compounds; and (iii) the incorporation of bistable MIMs into many different device settings associated with surfaces, nanoparticles and solid-state materials in response to the needs of particular applications that are perceived to be fair game for mechanostereochemistry.

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Molecular Knots

Cited by 97 publications

References 56 publications

The magic effect of endocyclic but non-sterically hindering biisoquinoline chelates: From fast-moving molecular shuttles to [3]rotaxanes

The magic effect of endocyclic but non-sterically hindering biisoquinoline chelates: From fast-moving molecular shuttles to [3]rotaxanes

Imaging of Catenated, Figure‐of‐Eight, and Trefoil Knot Polymer Rings

Mechanostereochemistry and the mechanical bond

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