Active‐Metal Template Synthesis of a Molecular Trefoil Knot

Barran, Perdita E.; Cole, Harriet L.; Goldup, Stephen M.; Leigh, David A.; McGonigal, Paul R.; Symes, Mark D.; Wu, Jia-Rong; Zengerle, Michael

doi:10.1002/anie.201105012

Cited by 142 publications

(60 citation statements)

References 77 publications

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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 34-37 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.…”

mentioning

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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mentioning

confidence: 99%

A synthetic molecular pentafoil knot

Ayme

Beves

Leigh³

et al. 2011

Nature Chem

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391

243

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“…By this analytical method, it was possible to separate compounds 12 and 12u, because they have different velocities which are due to their distinct sizes related to their unlike conformational structures. A similar analytical study was utilized by Leigh et al to distinguish a trefoil knot from its unknotted-macrocycle analogue [65]. Figure 4 shows the DT IM-MS results of various samples of a mixture of compounds 12/12u at the same concentration (5 × 10 −4 M) upon variation of the ratio of a solvent mixture of dichloromethane/acetonitrile.…”

Section: Studies Of the Equilibrium Between The Unthreaded Compound 1mentioning

confidence: 87%

A pH-Sensitive Peptide-Containing Lasso Molecular Switch

2013

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Abstract:The synthesis of a peptide-containing lasso molecular switch by a selfentanglement strategy is described. The interlocked [1] rotaxane molecular machine consists of a benzometaphenylene [25]crown-8 (BMP25C8) macrocycle surrounding a molecular axle. This molecular axle contains a tripeptidic sequence and two molecular stations: a N-benzyltriazolium and a pH-sensitive anilinium station. The tripeptide is located between the macrocycle and the triazolium station, so that its conformation can be tailored depending on the shuttling of the macrocycle from one station to the other. At acidic pH, the macrocycle resides around the anilinium moiety, whereas it shuttles around the triazolium station after deprotonation. This molecular machinery thus forces the lasso to adopt a tightened or a loosened conformation.

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“…Ursprünglich wurde dieser Ansatz fürd ie Vereinfachung von Rotaxan- [75,76] und Catenansynthesen [77] vorgestellt. Das Konzept konnte auch auf die Synthese eines molekularen Kleeblattknotens [78] (Schema 6) ausgeweitet werden. Ligand 18,m it einer Pyridyl-und zwei Bipyridyleinheiten, bindet ein Cu I -Ion zwischen den beiden Bipyridylgruppen und erzeugt so den ersten Kreuzungspunkt.…”

Section: Angewandte Chemieunclassified

Molekulare Knoten

Fielden¹,

Leigh²,

Woltering³

2017

Angewandte Chemie

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Der erste synthetische Kleeblattknoten wurde in den späten 1980er Jahren hergestellt. Kompliziertere Knotentopologien wurden jedoch erst in den letzten Jahren in molekularer Form erhalten. Die Verknotung molekularer Stränge erzeugt sterische Einschränkungen und kann so wichtige physikalische und chemische Eigenschaften verleihen, unter anderem Chiralität, starkes und selektives Binden von Ionen und katalytische Aktivität. Da die Anzahl und Komplexität molekularer Knoten steigt, wird es für Chemiker immer wichtiger, die Knotennomenklatur anderer Disziplinen zu verwenden. Hier geben wir einen Überblick über die Synthesestrategien für molekulare Knoten und beschreiben die Grundlagen der Knoten‐, Zopf‐ und Tangle‐Theorie in einem für Chemiker und molekulare Strukturen angemessenen Umfang.

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Active‐Metal Template Synthesis of a Molecular Trefoil Knot

Cited by 142 publications

References 77 publications

A synthetic molecular pentafoil knot

A synthetic molecular pentafoil knot

A pH-Sensitive Peptide-Containing Lasso Molecular Switch

Molekulare Knoten

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