Molecular Composite Knots

Carina, Riccardo F.; Dietrich-Buchecker, and Christiane; Sauvage, Jean‐Pierre

doi:10.1021/ja961459p

Cited by 126 publications

(69 citation statements)

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“…In a similar way, tied open-chain fragments have been combined experimentally by Sauvage and co-workers to make molecular composite knots. 12 Knots that cannot be constructed by such an addition are called prime knots, and it is this type of knot that we have been considering so far in this review.…”

Section: Molecules Containing Multiple Knotsmentioning

confidence: 99%

Knot theory in modern chemistry

et al. 2016

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(2016) 'Knot theory in modern chemistry.', Chemical society reviews., 45 (23). pp. 6432-6448. Further information on publisher's website:https://doi.org/10.1039/C6CS00448BPublisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Knot theory is a branch of pure mathematics, but it is increasingly being applied in a variety of sciences. Knots appear in chemistry, not only in synthetic molecular design, but also in an array of materials and media, including some not traditionally associated with knots. Mathematics and chemistry can now be used synergistically to identify, characterise and create knots, as well as to understand and predict their physical properties. This tutorial r eview provides a brief introduction to the mathematics of knots and related topological concepts in the context of the chemical sciences. We then survey the broad range of applications of the theory to contemporary research in the field. Key Learning Points Some fundamentals of knot theory.  Knot theory and closely related ideas in topology can be applied to modern chemistry.  Knots can be formed in single molecules as well as in materials and biological fibres using a mixture of selfassembly, metal templating and optical manipulation. The inclusion of knots in molecular structures can alter chemical and physical properties.  Knots are surprisingly ubiquitous in the chemical sciences.

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Section: Molecules Containing Multiple Knotsmentioning

confidence: 99%

Knot theory in modern chemistry

et al. 2016

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“…Although other syntheses of trefoil knots have been reported [15][16][17][18][19][20][21][22] (as have composites of trefoil knots 23 and other molecular topologies such as catenanes [24][25][26][27][28] and Borromean links 29 ), higher-order molecular knots remain elusive. Here, we report on the synthesis of a molecular pentafoil knot that combines the use of metal helicates to create crossover points 30 , anion template assembly to form a cyclic array of the correct size [31][32][33] , and the joining of the metal complexes by reversible imine bond formation [34][35][36][37] aided by the gauche effect 38 to make the continuous 160-atom-long covalent backbone of the most complex non-DNA molecular knot prepared to date.…”

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confidence: 99%

A synthetic molecular pentafoil knot

Ayme

Beves

Leigh³

et al. 2011

Nature Chem

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Knots are being discovered with increasing frequency in both biological and synthetic macromolecules and have been fundamental topological targets for chemical synthesis for the past two decades. Here, we report on the synthesis of the most complex non-DNA molecular knot prepared to date: the self-assembly of five bis-aldehyde and five bis-amine building blocks about five metal cations and one chloride anion to form a 160-atom-loop molecular pentafoil knot (five crossing points). The structure and topology of the knot is established by NMR spectroscopy, mass spectrometry and X-ray crystallography, revealing a symmetrical closed-loop double helicate with the chloride anion held at the centre of the pentafoil knot by ten CH ... Cl -hydrogen bonds. The one-pot self-assembly reaction features an exceptional number of different design elements-some well precedented and others less well known within the context of directing the formation of (supra)molecular species. We anticipate that the strategies and tactics used here can be applied to the rational synthesis of other higher-order interlocked molecular architectures.K nots are important structural features in DNA 1 , are found in some proteins [2][3][4][5] and are thought to play a significant role in the physical properties of both natural and synthetic polymers 6,7 . Although billions of prime knots are known to mathematics 8 , to date the only ones to have succumbed to chemical synthesis using building blocks other than DNA are the topologically trivial unknot (that is, a simple closed loop without any crossing points) and the next simplest knot (featuring three crossing points), the trefoil knot 9,10 . A pentafoil knot-also known as a cinquefoil knot or Solomon's seal knot (the 5 1 knot in Alexander-Briggs notation 11 )-is a torus knot 12 with five crossing points, is inherently chiral, and is the fourth prime knot (following the unknot, trefoil knot and figure-of-eight knot) in terms of number of crossing points and complexity 8,11,12 .Sauvage reported the first molecular knot synthesis 13 , using a linear metal helicate 14 to generate the three crossing points required for a trefoil knot. Although other syntheses of trefoil knots have been reported [15][16][17][18][19][20][21][22] (as have composites of trefoil knots 23 and other molecular topologies such as catenanes [24][25][26][27][28] and Borromean links 29 ), higher-order molecular knots remain elusive. Here, we report on the synthesis of a molecular pentafoil knot that combines the use of metal helicates to create crossover points 30 , anion template assembly to form a cyclic array of the correct size [31][32][33] , and the joining of the metal complexes by reversible imine bond formation 34-37 aided by the gauche effect 38 to make the continuous 160-atom-long covalent backbone of the most complex non-DNA molecular knot prepared to date.So far, attempts to make molecular knots with more than three crossing points by extending the linear helicate strategy of Sauvage to ligands with more coordination sites...

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“…[8][9][10][11][12][13][14][15][16][17][18][19]). Furthermore, crystal engineers have produced coordination networks that contain knots and links [6].…”

Section: Introductionmentioning

confidence: 99%