Stereoselective Synthesis of a Topologically Chiral Molecule: The Trefoil Knot

Perret-Aebi, Laure-Emmanuelle; Zelewsky, Alex von; Dietrich‐Buchecker, Christiane; Sauvage, Jean‐Pierre

doi:10.1002/ange.200460250

Cited by 45 publications

(19 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…When cyclized under RCM conditions this generated a homochiral trefoil knot, 213-Cu I , in 74 % yield (Scheme 81). [313] The single handedness of the knot was established by the presence of a strong signal in the circular dichromism spectrum of 213-Cu I . Demetalation gave the metal-free homochiral knot.…”

Section: Stereoselective Synthesis Of a Trefoil Knot Using Two Tetrahmentioning

confidence: 99%

Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links

et al. 2011

View full text Add to dashboard Cite

More than a quarter of a century after the first metal template synthesis of a [2]catenane in Strasbourg, there now exists a plethora of strategies available for the construction of mechanically bonded and entwined molecular level structures. Catenanes, rotaxanes, knots and Borromean rings have all been successfully accessed by methods in which metal ions play a pivotal role. Originally metal ions were used solely for their coordination chemistry; acting either to gather and position the building blocks such that subsequent reactions generated the interlocked products or by being an integral part of the rings or "stoppers" of the interlocked assembly. Recently the role of the metal has evolved to encompass catalysis: the metal ions not only organize the building blocks in an entwined or threaded arrangement but also actively promote the reaction that covalently captures the interlocked structure. This Review outlines the diverse strategies that currently exist for forming mechanically bonded molecular structures with metal ions and details the tactics that the chemist can utilize for creating cross-over points, maximizing the yield of interlocked over non-interlocked products, and the reactions-of-choice for the covalent capture of threaded and entwined intermediates.

show abstract

Section: Stereoselective Synthesis Of a Trefoil Knot Using Two Tetrahmentioning

confidence: 99%

Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links

et al. 2011

View full text Add to dashboard Cite

show abstract

“…As emphasized in the schematic representations (Figure 2 c, d, inset), the path of the knot crosses over itself three times. As previously described, [39,40] trefoil knots are topological stereoisomers of the corresponding simple rings. As previously described, [39,40] trefoil knots are topological stereoisomers of the corresponding simple rings.…”

Section: Michel Schappacher and Alain Deffieux*mentioning

confidence: 99%

“…This pattern corresponds to the simplest knotted ring structure (trefoil). As previously described, [39,40] trefoil knots are topological stereoisomers of the corresponding simple rings. As shown in Figure 2, the isomers exist in the form of right and left topological diastereoisomers.…”

Section: Michel Schappacher and Alain Deffieux*mentioning

confidence: 99%

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

Schappacher

Deffieux

2009

Angewandte Chemie

View full text Add to dashboard Cite

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 ...

show abstract

“…For example, differing from the case of Hückel annulenes (two-sided surfaces) with 4n+2  electrons to be aromatic, the Möbius annulenes (one-sided surface) with 4n  electrons are aromatic. Moreover, Möbius annulenes exhibit unusual ring currents [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Imitating trumpet shells: Möbius container molecules

Wang

et al. 2011

Sci. China Chem.

View full text Add to dashboard Cite

sided characteristics were constructed at the first time by imitating natural trumpet shells. The structure is an open cage with an inner hexagonal bridge. The bridge joints the outer and inner surfaces of the cage to form a new one-sided Möbius structure. The optimized structures of the three molecules in the singlet (the ground state), triplet and quintet states are obtained using the density functional theory (B3LYP). For the ground state structures of the three Möbius molecules, their oxidizabilities are weaker than that of the C 60 and reducibilities are close to that of the stable C 80 cage and slightly stronger than that of the C 60 . These may show that the unusual Möbius structures have some stability. Their potential properties were predicted, for example, the special aromaticity of the bridge ring due to the unique interaction between the bridge and the cage wall. These findings enlarge the knowledge of Möbius molecules. The idea of bionic and topological imitating in chemistry may promote the design of new complex-shaped nano-molecules and molecular devices. aromaticity, density functional calculation, IR spectroscopy, Möbius strip, molecular container

show abstract

Stereoselective Synthesis of a Topologically Chiral Molecule: The Trefoil Knot

Cited by 45 publications

References 30 publications

Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links

Strategies and Tactics for the Metal‐Directed Synthesis of Rotaxanes, Knots, Catenanes, and Higher Order Links

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

Imitating trumpet shells: Möbius container molecules

Contact Info

Product

Resources

About