Chiral Spaces: Dissymmetric Capsules Through Self-Assembly

Rivera, José M.; Martı́n, Tomás; Rebek, Julius

doi:10.1126/science.279.5353.1021

Cited by 196 publications

(82 citation statements)

References 21 publications

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“…Amber* minimization of the complex between 2´2 and 11 shows the participation of the acidic hydroxyl group in a hydrogen bond with the carbonyls on the glycolurils. In this respect, molecule 3, [22] which forms dimer 3´3 featuring a chiral cavity, is particularly revealing. A molecular dynamics simulation of the complex between this dimer and 27 (V 173…”

Section: Methodsmentioning

confidence: 98%

The 55 % Solution: A Formula for Molecular Recognition in the Liquid State

1998

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Evidence is presented that molecular recognition through encapsulation processes is largely determined by the volumes of the guest and host. Binding of molecules of suitable dimensions in the internal cavity of a molecular receptor in solution can be expected when the packing coefficient, the ratio of the guest volume to the host volume, is in the range of 0.55 AE 0.09. Larger packing coefficients, up to 0.70, can be reached if the complex is stabilized by strong intermolecular forces such as hydrogen bonds. These considerations also apply to situations in which more than one molecule is encapsulated. Organic liquids are generally characterized by the same packing factors as encapsulation complexes, and it is proposed that the short-range structure of liquids and the complexes resulting from encapsulation are two aspects of the same phenomenon. Similar volume considerations are expected to apply to the binding of substrates in biological receptors.

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Section: Methodsmentioning

confidence: 98%

The 55 % Solution: A Formula for Molecular Recognition in the Liquid State

1998

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“…What remains to be challenged is finite divergent associations with number, size, and shape control as a nano(bio)technological tool to construct functional nanometric or mesoscopic devices, the bottom-up or template-and-ball approach to artificial viruses being an example. This fascinating area will grow keeping in touch with such topics as number and size control in supramolecular oligomerization, [18] finite macromolecular association, [19] topologically programmed multimolecular metal coordination, [20] and hierarchical self-assembly. [21] …”

Section: Hierarchical Adhesion Control: Concluding Remarksmentioning

confidence: 99%

Macrocyclic Glycoclusters: From Amphiphiles through Nanoparticles to Glycoviruses

Aoyama

2004

Chemistry A European J

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Macrocyclic glycocluster amphiphiles are intended to be a covalent-bundle mimic of clustering glycolipid motifs on the cell membrane. They are irreversibly micellized to give glycocluster nanoparticles (GNPs); their masked hydrophobicity endows them with remarkable saccharide specificities in the interactions with biological saccharide receptors. The GNPs also exhibit unprecedented hydrogen-bond capacities; they are agglutinated with Na(2)HPO(4) and assembled on plasmid DNA in a number-, size-, and shape-controlled manner to give artificial glycoviral particles capable of transfection. Thus, the intrinsic function of viruses, that is, cell invasion followed by gene expression, is also intrinsic to size-regulated (approximately 50 nm) glycoviruses. The growth of glycocluster amphiphiles through nanoparticles to glycoviruses reveals a hierarchical adhesion control of the saccharide clusters.

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“…[5] It is formed when two selfcomplementary subunits 1 a dimerize in organic solvents through a seam of eight hydrogen bonds. The subunits feature a plane of symmetry and are achiral, but the dimer has only C 2 axes and exists as a pair of enantiomers.…”

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confidence: 99%

Chiral Guests and Their Ghosts in Reversibly Assembled Hosts

Martin

et al. 2000

Angew. Chem. Int. Ed.

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Encapsulation complexes are assemblies in which small molecular guests are completely by large molecular hosts. [1±4] The hosts are made up of subunits held together by intermolecular forces: hydrogen bonds, van der Waals forces, and/or metal ± ligand interactions. The assemblies are formed reversibly and are dynamic; they come together and dissipate on time scales ranging from milliseconds to days, long enough for their study by NMR methods. When multiple hosts can assemble from a given set of subunits, template effects can be expected and these have recently been reported. [5±9] Here we report an encapsulation complex with the additional characteristic that hydrogen bonds maintain an im-printÐthe ghostÐof a long-departed guest. Specifically, an asymmetric microenvironment is imprinted in a reversibly formed capsular host by a chiral guest template. Removal of the template leaves a chiral, nonracemic (g)host capsule that can be characterized by NMR spectroscopy. Recognition of the guest rather than its mirror image persists for hours in organic solvents.We recently reported a capsule known as the chiral ªsoftballº 1 a´1 a (Scheme 1 a). [5] It is formed when two selfcomplementary subunits 1 a dimerize in organic solvents through a seam of eight hydrogen bonds. The subunits feature a plane of symmetry and are achiral, but the dimer has only C 2 axes and exists as a pair of enantiomers. The cavity of the capsule is a distorted sphere and asymmetric guests generally prefer one enantiomer of the capsule to its mirror image. The enantiomeric capsules can interconvert (racemize) only by complete dissociation and recombination of their subunits (monomer exchange). Evidence reported elsewhere [10±12] indicates that guests get in and out of these capsules through flaps that are opened by the breaking of hydrogen bonds as conformational changes occur.A related structure 1 b was prepared for the imprinting studies. [13] It dimerizes into capsules that are more robust and assemble in a number of solvents. The phenolic groups introduce four additional hydrogen bonds in the corresponding capsule 1 b´1 b and slow its rate of racemization. Figure 1 shows how the NMR spectrum of 1 b´1 b with added chiral Scheme 1. a) Structure of the monomer 1 b and model of its dimeric assemblies. [22] Some protons and n-heptylphenyl groups in the dimers are omitted for clarity. Atoms are colored as follows: carbon and hydrogen: orange, oxygen: red,s nitrogen: blue. b) Guests used in the study. Figure 1. Portions of the 1 H NMR spectra showing the selected NH peaks of the dimer (8.65 ± 8.45 ppm) and H a peaks for the guest inside the capsules (2.90 ± 2.60 ppm). The labels A and A' denote the thermodynamically more-stable complexes of ()-2 and (À)-2, respectively, while B and B' denote the respective less-stable complexes. a) 1 b´1 b in [D 10 ]p-xylene (8.25 Â 10 À4 m); b) 4 min and c) 120 h after addition of 3 equiv of ()-2; d) 17 min and e) 191 h after addition of 30 equiv of (À)-2. guest, ()-pinanediol (()-2; Scheme 1 b), varies with tim...

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Chiral Spaces: Dissymmetric Capsules Through Self-Assembly

Cited by 196 publications

References 21 publications

The 55 % Solution: A Formula for Molecular Recognition in the Liquid State

The 55 % Solution: A Formula for Molecular Recognition in the Liquid State

Macrocyclic Glycoclusters: From Amphiphiles through Nanoparticles to Glycoviruses

Chiral Guests and Their Ghosts in Reversibly Assembled Hosts

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