The monosubstituted cyclomaltoheptaose derivative, 6I-(6-aminohexyl)amino-6I-deoxycyclomaltoheptaose, crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 32.513(2), b = 15.3871(9), c = 15.2645(9) A, V = 7636.6(8) A3 and Z = 4. The macrocycles are spirally aligned along the twofold screw axis parallel to the c crystal axis forming polymeric-like columns. The 6-aminohexyl chain enters the cavity of an adjacent cyclomaltoheptaose moiety in the column from the secondary side and its extremity protrudes from the primary side of the latter. All the atoms of the chain exhibit high thermal motion.

The structure of the title compound provides the first illustration of direct coordination of a polyvalent cation, as well as an inorganic anion, by β-cyclodextrin (β-CD). Crystal data: P212121, Z = 4, a = 15.875 (1), b = 17.583 (1), c = 24.270 (2) Å, V = 6775 (1) Å3, R = 0.059 for 4744 unique observed reflections with I > 3σ(I). There are two CaCl2 per β-CD, with no direct contacts between the ions. None of the ions are included within the cyclodextrin cavity. The cations are in direct interaction simultaneously with two or three β-CD molecules and an eightfold coordination occurs for both. No disorder was found except for the two water molecules situated inside the cavity. The crystalline form is a novel monomer-type structure. The β-CD molecules are stacked as monomer entities inclined at ~50° along a twofold screw axis, such that they are arranged in a new herringbone-like scheme. The overall packing is stabilized by intermolecular interactions between cyclodextrin monomers and by direct coordination to the ions. Moreover, the cohesion is reinforced by hydrogen bonds involving water molecules arranged in infinite chain motifs traversing the whole structure.

Two interlocking substructures–infinite chains of β‐cyclodextrin monomers and [Mg(H2O)6]Cl2building blocks–form the basis of a novel composite. The chains of inorganic components, comprising Mg(H2O)6octahedra linked through Cl anions and water of crystallization, are threaded through the cavities of the cyclodextrins. The complete structure is stabilized by hydrogen bonds.

The first crystallographic example of a P-cyclodextrin monosubstituted at O6 by a bulky group possessing two terminal apolar side chains, tert-butoxycarbonyl-L-phenylalanylamino (Boc-L-Phe-NH), illustrates an unusual cyclodextrin host/guest organisation. The structure is a novel packing of monomer units. Two symmetry independent Boc-L-Phe-NH-beta-CD molecules are stacked parallel to the two-fold screw axis forming two independent alternate ''endless screw head-to-tail'' channels. Both apolar side chains are at the exterior of the intramolecular cavity and are fully enclosed within the channels: the phenyl ring of the amino residue lies above the parent macrocycle while the tert-butyl group is intermolecularly included within a neighbouring molecule. Water molecules Located outside the monomeric cavities over 34 sites, all but one external to the channels, fill the intermolecular spaces and reinforce the cohesion of the structure.

The formation of micelles, vesicles and monomolecular layers by amphiphilic cyclodextrins possessing hydrophobic ester groups on the secondary hydroxyl face is described. The physico-chemical properties of these self-organizing systems were studied by dynamic light scattering, variable-temperature H-1 NMR, the use of lanthanide shift reagents, deposition of Langmuir layers, variable-temperature solubility measurements and aqueous and non-aqueous surface tension activity measurements. The results are interpreted in terms of the cylindrical geometry of the compounds which, coupled with the presence of a large planar polar head group, leads to the formation of self-organized systems both in polar organic solvents and also al the air-water interface.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-assembling systems of the amphiphilic cationic per-6-amino-.beta.-cyclodextrin 2,3-di-O-alkyl ethersHelene Parrot-Lopez, Chang Chun Ling, Ping Zhang, Adam Baszkin, Genevieve Albrecht, Colette De Rango, and Anthony W. ColemanCite this: J. Am. Chem. Soc. 1992, 114, 13, 5479–5480Publication Date (Print):June 1, 1992Publication History Published online1 May 2002Published inissue 1 June 1992https://pubs.acs.org/doi/10.1021/ja00039a100https://doi.org/10.1021/ja00039a100research-articleACS PublicationsRequest reuse permissionsArticle Views797Altmetric-Citations86LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT.beta.-cyclodextrin/pyridine gel systems. The crystal structure of a first .beta.-cyclodextrin-pyridine water compoundColette De Rango, Pierrette Charpin, Jorge Navaza, Nelly Keller, Ioannis Nicolis, Francoise Villain, and Anthony W. ColemanCite this: J. Am. Chem. Soc. 1992, 114, 13, 5475–5476Publication Date (Print):June 1, 1992Publication History Published online1 May 2002Published inissue 1 June 1992https://pubs.acs.org/doi/10.1021/ja00039a097https://doi.org/10.1021/ja00039a097research-articleACS PublicationsRequest reuse permissionsArticle Views567Altmetric-Citations50LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

C42H70O35.K+.OH-.8H2O, M(r) = 1335.24, monoclinic, P2(1), a = 15.223 (5), b = 10.578 (3), c = 20.204 (6) angstrom, beta = 108.37 (7)-degrees, V = 3087 angstrom 3 Z = 2, D(x) = 1.436 Mg m-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 1.876 mm-1, F(000) = 1420, T = 295 K, final R = 0.080 for 4774 observed reflections. The cyclodextrin molecules are stacked, as monomeric entities, inclined at 43.4-degrees along the twofold screw axis, forming a classical herringbone scheme. Three O atoms, attributed to water molecules, are found inside the cyclodextrin cavity, two of them being hydrogen bonded to the two primary hydroxyl groups which are in a gauche-trans conformation. Six others, present as doublets or singlets of water molecules, are located between the cyclodextrin entities and ensure the packing via hydrogen bonding. The potassium ion is incorporated in an interstitial site and coordinated to six non-water O atoms which belong to four different cyclodextrin units, in a distorted trigonal-prism environment. It is suggested that the balancing negative charge is localized inside the cavity, one of the three water molecules being in fact a hydroxyl anion.

4[U(CF 3 COO) 4 (H 2 O) 0,5 ]•2C 18 H 36 N 2 O 6 cristallise dans P1 avec a=13,003, b=13,338, c=16,738 A, α=84,36, β=68,71, γ=87,19°, Z=1, affinement jusqu'a R=0,038. Les quatre atomes U sont relies par des coordinats trifluoracetate et des molecules d'eau formant ainsi une unite neutre tetramerique centrosymetrique dans laquelle les quatre atomes U sont situes a 4,0769 et 3,5969 A des coins d'un losange. Le groupe trifluoroacetate se compose soit comme groupe monodente soit comme pont; il n'existe pas de contacts significatifs entre les unites tetrameres et cryptands

A new mathematical description of phase relationships which connects different approaches, both in reciprocal and direct space, is formulated. It leads to the development of a novel algorithm for phase extension and refinement based on a probability function for atomic presence. This function, calculated from the elements of the Karle-Hauptman inverse matrix, is used in an iterative procedure. Various tests have been performed on an idealized set of calculated structure factors for an insulin model structure. The method has been applied to experimental data, Fobs, and the isomorphous phases for 2Zn insulin. An assessment of the quality of the phase refinement and calculation has been made by comparison with the crystallographically refined phases.

Several geometrical characteristics of 6-, 7-, 10-, 11- helicene have been studied: accuracy of the binary axis, distribution of atoms over three helices, bond distances and angles, planarity and interplanar angles of benzene rings, existence of new planar groups. Two types of general models are suggested and discussed: the triple helix and the staircase model.

1 H N.m.r. evidence for direct co-ordination of uranium to the oxygen atoms in a new UCl4-dicyclohexyl-18-crown-6 complex is confirmed by an X-ray structural determination; several uranium(IV) salt–crown-ether complexes and cryptates also exhibiting very large n.m.r. shifts are reported.

Further investigation of the Karle-Hauptman determinants leads to several new relations: the DN determinant is simply related to interatomic vectors; also obtained is a probabilistic restriction on the atomic positions inside the algebraically allowed regions, as defined by von Eller. On the other hand new Gram determinants are defined and shown to be useful in relating moduli, phases and interatomic vectors. A practical application is given of fitting a stereochemically known fragment in the unit cell.