Anionic Host Research Articles

Heteronetwork clathrates with three-dimensional mixed silicate–water host frameworks and channel systems

X-Ray structure analysis reveals that in the crystalline silicate hydrates with the approximate chemical compositions [NPhMe3]6[Si8O18(OH)2]·38.7H2O and [NBnMe3]8[Si8O20]·53.6H2O (Bn = benzyl) cube-shaped octameric silicate anions and water molecules are linked via hydrogen bonds to form 3D mixed anionic host framework with channel systems; the interionic O ⋯ CH3(N) anion-cation interactions observed in the heteronetwork clathrates are of particular interest with regard to a very recently proposed mechanism for the formation of mesoporous silicate materials (M41S).

Structure of bis(2-amino-5-nitropyridinium) dichromate as a step towards the design of efficient organic–inorganic non-linear optical crystals

The orthorhombic crystal structure of 2C 5 H 6 N 3 O 2 + .- Cr 2 O 7 2- (a=22.454 (6), b=15.129 (2), c=5.189 (2) A, Z=4, orthorhombic, P2 1 nb, D x =1.866 g cm -3 ] has been solved using direct methods and refined to wR=0.029 for 2514 reflections. This study provides a step towards a new route to obtain non-linear optical crystals which aims at combining the highly polarizable 2-amino-5-nitropyridinium cation with inorganic anionic host matrices. The shielding effect of dichromate anions in the building of an acentric polar framework is discussed

A Novel Host/Guest System with a Nanometer Large Cavity for Anions and Cations: [2NH, 2Cl− ⊂ V14O22(OH)4(H2O)2‐(C6H5PO3)8]6−

A polytopic host for several cations and anions or cation/anion aggregates was previously unknown. The anion of the title (structure depicted on the right) is a host/guest system in which the “host”—the shell—consists of electrophilic and nucleophilic components. The cation/anion aggregate (NH4)2Cl2, a section of the NH4Cl ion lattice, is incorporated as “guest”.

Density-functional approach for superionic conductors: effects of host-lattice deformations

By means of classical density-functional theory the authors study the density distribution of mobile Ag+ ions in alpha -AgI-type superionic conductors taking into account the thermal fluctuations in the anion host lattice. Their model is based on an expansion of the 'external' potential v(r) acting on the cation-component up to second order in the displacements of anions, the latter being regarded as Einstein oscillators. Calculated density profiles are compared with molecular-dynamics simulations. For alpha -AgI the agreement is almost quantitative. In the case of beta -Ag2S the inclusion of anion vibrations leads to significant corrections in the temperature-dependent profiles.

ChemInform Abstract: Artificial Molecular Anion Hosts. Synthesis of a Chiral Bicyclic Guanidinium Salt Serving as a Functionalized Anchor Group for Oxo Anions.

ChemInform Abstract: Artificial Molecular Anion Hosts. Synthesis of a Chiral Bicyclic Guanidinium Salt Serving as a Functionalized Anchor Group for Oxo Anions.

ChemInform Abstract: Selective Molecular Hosts for Anions

ChemInformVolume 21, Issue 16 Reviews ChemInform Abstract: Selective Molecular Hosts for Anions F. P. SCHMIDTCHEN, F. P. SCHMIDTCHEN Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this authorA. GLEICH, A. GLEICH Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this authorA. SCHUMMER, A. SCHUMMER Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this author F. P. SCHMIDTCHEN, F. P. SCHMIDTCHEN Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this authorA. GLEICH, A. GLEICH Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this authorA. SCHUMMER, A. SCHUMMER Org. Chem. Inst., TU Muenchen, D-8046 GarchingSearch for more papers by this author First published: April 17, 1990 https://doi.org/10.1002/chin.199016368Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue16April 17, 1990 RelatedInformation

Künstliche molekulare Anion‐Wirte. Die Synthese eines chiralen bicyclischen Guanidinium‐Salzes als funktionalisierte Ankergruppe für Oxo‐Anionen

Artificial Molecular Anion Hosts. Synthesis of a Chiral Bicyclic Guanidinium Salt Serving as a Functionalized Anchor Group for 0x0 AnionsStarting from 1‐asparagine, the synthesis of the S,S‐bis(hydroxymethyl)‐substituted bicyclic guanidinium salt 3 is described, which is obtained in 20% overall yield with a diastereomeric excess de > 98%. The guanidinium compound 3 may serve as a binding module in the enantioselective recognition of oxo anions in polytopic abiotic receptors.

Polyhedral clathrate hydrates of a strong base: Phase relations and crystal structures in the system tetramethylammonium hydroxide-water

The tetramethylammonium hydroxide-water system has been studied by low-temperature differential thermal analysis and X-ray powder diffraction. The melting diagram was constructed for concentrations between 66.7 and 100 mol% H2O. It shows the existence and stability ranges of as many as eight crystalline hydrate phases:α- andβ-Me4NOH·2H2O (phase transition at −85°C, decomposition atca. 105°C), Me4NOH·4 H2O (melting point 44°C, incongruent),α andβ-Me4NOH·5 H2O (phase transition at 42°C, melting point 68°C, congruent),α- andβ-Me4NOH·7.5 H2O (phase transition at 6°C, melting point 16°C, incongruent), and Me4NOH·10 H2O (melting point −20°C, incongruent). The structures of all these phases, except the already known one ofα-Me4NOH·5 H2O, were determined from single-crystal MoKα diffractometer data. The decahydrate and the high-temperatureβ forms of the 7.5-hydrate and the pentahydrate are genuinepolyhedral clathrate hydrates, the first ones reported of a strong base. Their mostly novel three-dimensional anionic host structures, formed by the hydrogen-bonded OH− ions and H2O molecules, arefour-connected throughout, in spite of their proton deficiency which is apparently leveled by disorder. Disorder also affects the enclosed cationic Me4N+ guest species. Like the low-temperatureα form of the pentahydrate, that of the 7.5-hydrate has a clathrate-related, but not fully polyhedral structure, some of the oxygen atoms being three-connected only. The tetrahydrate presents the rare case of both a hydrogen bond of the type OH−...OH2 and a (deprotonated) water-channel structure. This is fully ordered and apart from that can be derived from the polyhedral one of theβ-pentahydrate just by removing the appropriate number of water molecules from certain positions. The structures ofα- andβ-Me4NOH·2 H2O contain identical one-dimensionalspiro chains [HO−(HOH)/42] with the hydroxide protonnot participating in the hydrogen bonding. The Me4N+ ion is ordered in theα and disordered in theβ phase.

Selective molecular hosts for anions

Abstract

Multiple recognition in polytopic anion hosts

Selectivity in guest binding by biogenic or abiotic receptors depends on the type, number, spatial orientations and overall flexibility of the ensemble of recognition sites interacting with the substrates. The putatively optimal approach to construct a selective host compound is to arrange anchor groups on a rigid concave molecular framework capable of inclusion of the guest species. This route, however, may soon reach the limits of synthesizability if polyfunctional biologically relevant guests (nucleotides, hormones, coenzymes) are to be selectively bound.

Tetraethylammonium chloride tetrahydrate, a ?double channel? host lattice constructed from (H2O)4Cl? tetrahedra linked between vertices

Crystals of (C2H5)4NCl·4H2O are orthorhombic, space groupCcca, witha=19.104(3),b=23.084(4),c=13.330(3) A, andZ=16. The structure features an anionic host lattice constructed from the linkage of (H2O)4Cl− tetrahedra by hydrogen bonds between vertices, generating two open linear channel systems which accommodate the ordered cations. FinalRF=0.080 for 1516 observed MoKα data measured at 22°C.

Anionic Host Molecules with Bicyclic Carbon Skeletons—Synthesis and Guest Inclusion in Aqueous Solution

Anionic Host Molecules with Bicyclic Carbon Skeletons—Synthesis and Guest Inclusion in Aqueous Solution

Raman spectra of InI, InI2 and InI3. Correlation between structure and thermodynamic properties of fused InxI1–x mixtures

We have measured the Raman spectra of InI, InI2 and InI3 in both the high-temperature solid and the melt. Each of these materials, except for InI3, undergoes a polymorphic transition at high temperatures that can be detected by recording the Raman spectra as a function of temperature, as well as by scanning calorimetric analyses. The Raman results for InI2 demonstrate that the In+ ion is surrounded by units of the complex anion InI–4; since both InI and InIII exist as separate entities in InI2 it can be called an inhomogeneously mixed-valent compound. These results at room temperature are consistent with the previous i.r. study. The Raman spectra of molten InI2 and InI3 are given by parallel and perpendicular components. The decomposition of the parallel spectrum led to the conclusion that the complex ion InI–4 is stable as a host for anions in the molten InI2. Previous work on the thermodynamic properties of fused InxI1–x mixtures showed that the partial molar entropy of In has a drastic excursion near x= 0.333 (or InI2), whereas in the corresponding region there is a prominent change in the liquid structure from a Coulombic interaction between In+ and I– in molten InI to that between In+ and InI–4 as an anion host. The complex anions are stabilized by covalent bonding centred on InIII because of the magnitude of the stretching force constant K of the In—I bond in InI–4.

Polyhedral Clathrate Hydrates. V. Structure of the Tetra-n-butyl Ammonium Fluoride Hydrate

The structure of (n-C4H9)4N+F—·32.8 H2O is tetragonal, of space group P42/m with the unit-cell dimensions a=23.52 Å and c=12.30 Å. The clathrate host structure is similar to that of the (n−C4H9)4N+C6H5−COO−·39.5 H2O and consists of a tetragonal pseudo body-centered arrangement of groups of five face-sharing pentagonal dodecahedra interlinked by tetrakaidecahedra and pentakaidecahedra. Whereas in the benzoate there are four salt molecules per unit cell, in the fluoride there are five. This difference in the number of guests accommodated in essentially the same host structure is possible because the four tetrakaidecahedra occupied by the benzoate groups are available for the four alkyl groups of the additional cation. In the fluoride hydrate, four of the cations have the central N+ atom at the fourfold positions (j) and that of the fifth is disordered over the twofold position (f). Thus the structure has lower symmetry than the benzoate hydrate, which is P42/mnm by reason of the disorder of the four cations over eightfold positions. The fluoride ions replace water molecules in the host lattice, with F—···O distances of 2.80 to 2.87 Å forming an anionic host lattice. As in the other clathrate hydrate structures of this type, some of the pentagonal dodecahedra which are distorted by the presence of the cations are occupied by a guest species presumed to be additional water molecules.