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One-dimensional Channels (one-dimensional + channel)
Selected AbstractsSize-Selective Sorption of Small Organic Molecules in One-Dimensional Channels of an Ionic Crystalline Organic,Inorganic Hybrid Compound Stabilized by ,,, Interactions,ANGEWANDTE CHEMIE, Issue 33 2009Hanae Tagami Sehr selektiv: Der Durchmesser der engsten Kanalöffnung in einem organisch-anorganischen porösen Ionenkristall mit eindimensionalen Kanälen beträgt etwa 30,Å2. Die Verbindung sorbiert Moleküle wie Propan, 1-Propanol und 1,2-Dichlorethan, deren Querschnitte kleiner als die Kanalöffnung sind, während n -Butan, 1-Butanol und 1,2-Dichlorpropan ausgeschlossen bleiben (siehe Bild). [source] Progress in SWNT based, SAW driven charge pumpsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006Viktor Siegle Abstract The work presented gives a short overview of existing implementations for single electron pumps. A proposal by Talyanskii et al. [Phys. Rev. Lett. 87, 276802 (2001)] for a single walled carbon nanotube (SWNT) based device is discussed. SWNT is suggested to function as one-dimensional channel for electrons, which are driven by the surface acoustic wave (SAW). The SAW is created on the surface of a piezoelectric by lithographically defined structures. This work addresses the details in manufacturing such a device. This work investigates the possibilities of growing SWNTs by chemical vapor deposition (CVD) on the surface of LiNbO3, which is known for its excellent piezoelectric properties. The results of this study are reported together with the progress in fabrication of such a device. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Poly[diaquabis(,3 -hexamethylenetetramine)[,2 -2,2,-(piperazine-1,4-diyl)bis(ethanesulfonato)]disilver(I)]: a three-dimensional pillared-layer framework encapsulating a water chain of (H2O)12 clustersACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010Peng Guo The title compound, {[Ag2(C8H16N2O6S2)(C6H12N4)2(H2O)2]·12H2O}n, consists of a two-dimensional AgI,hexamethylenetetramine (6,3) net pillared by the 2,2,-(piperazine-1,4-diyl)bis(ethanesulfonate) ligand, which lies across a centre of inversion. This compound can also be viewed as a (3,4)-connected topology by considering the hexamethylenetetramine ligand and the AgI ion as the three- and four-connected nodes, respectively. There is a one-dimensional channel along the a axis accommodating a water chain assembled by the (H2O)12 clusters. [source] Tris(1,10-phenanthroline-,2N,N,)cadmium(II) bis(perchlorate) 3.5-hydrate: a water chain stabilized by perchlorate anionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Yu-Hui Sun The title compound, [Cd(C12H8N2)3](ClO4)2·3.5H2O, contains a cross-shaped one-dimensional channel along the c axis which encapsulates an ordered water chain. This water chain features a centrosymmetric cyclic water hexamer unit with a chair-like conformation. Neighbouring hexamers are linked by bridging water molecules. The host perchlorate anions recognize and stabilize the guest water chain via three kinds of hydrogen-bond patterns, leading to the formation of a complex one-dimensional {[(H2O)7(ClO4)4]4,}n anionic chain. One perchlorate acts as a single hydrogen-bond acceptor dangling on the chain, the second perchlorate on the chain serves as a double hydrogen-bond acceptor for only one water molecule to form an R22(6) ring, where both entities lie on a twofold axis, while the third perchlorate, which also lies on a twofold axis, accepts two hydrogen bonds from two equivalent water molecules and is involved in the construction of an R65(14) ring. [source] Energy Collection, Transport, and Trapping by a Supramolecular Organization of Dyes in Hexagonal Zeolite Nanocrystals,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2006C. Minkowski Abstract The incorporation of guest molecules into the cavities of molecular sieves leads to a large variety of highly interesting materials. Zeolite,L,an aluminosilicate with one-dimensional channels of open diameter 7.1,Å,is a very versatile material for building highly organized host,guest systems. We present materials where organic dye molecules have been incorporated into the channels of zeolite,L by means of diffusion, to build artificial photonic antenna systems. The channel entrance can be plugged by adding closure molecules that then connect the guest molecules inside with materials or molecules outside of the zeolite channels, since they can act as extensions of the interior of the zeolite crystal. The photophysical processes taking place in such dye-loaded zeolite,L antennae can be studied either on single-micrometer- or submicrometer-sized crystals or on crystals dispersed in a solvent or coated as thin layers on a support. The energy-transfer process occurring is of the Förster-type, and its transfer rate can be tuned by separating the donor dyes and the acceptor dyes locally by varying amounts of spacer molecules. The distribution of the dye molecules and empty sites within a zeolite crystal has been modeled by means of a Monte Carlo simulation. The Förster energy migration and transfer steps are described as a random walk. [source] Structure of lithium benzilate hemihydrate solved by simulated annealing and difference Fourier synthesis from powder dataACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2003Asiloé J. Mora The crystal structure of lithium benzilate hemihydrate (C14H11OLi+·0.5H2O) was solved from synchrotron powder diffraction data. This compound crystallizes in the monoclinic space group P21/a. The structure was solved via the direct space search for two benzilate fragments using the simulated-annealing program DASH, localization of the lithium ions and water molecule from a difference Fourier map, and a restrained Rietveld refinement (Rwp = 0.0687). The structure is a coordination polymer of [Li2(C14H11O3)2·H2O]2 tetramers building helical fourfold one-dimensional channels parallel to [010]. Inside the channels the tetrahedral coordination spheres of the lithium ions contain hydroxyl and carbonyl groups, and water molecules. The water molecule functions as the cohesive entity forming extended hydrogen-bonded chains running along [010], and bifurcated donor hydrogen bonds with the two nearest carboxylates. At the outer edge of the channels, weaker intermolecular C,H,Ph hydrogen bonds along [100] and [001] contribute to the supramolecular aggregation of the structure. [source] Loading Dependence of Self-Diffusivities of Gases in ZeolitesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2007R. Krishna Abstract Experimental data on the self-diffusivities, Di,self, of a variety of gases (CH4, N2, Kr, C2H6, and C3H8) in three different zeolites, LTA, FAU, and MFI, show different dependences on the molar loading, qi. In LTA, Di,self appears to increase with qi for all molecules except N2. In FAU and in MFI the Di,self shows a sharp decrease with increasing qi. In order to gain insights into the causes behind the loading dependences, molecular dynamics (MD) simulations were carried out to determine the self-diffusivities of seven gases (CH4, N2, Kr, C2H6, C3H8, Ar, and Ne) in six different all-silica zeolite structures (MFI, AFI, FAU, CHA, DDR, and LTA). The simulation results show that the variation of Di,self with qi is determined by a variety of factors that include molecular size and shape, and degree of confinement within the zeolite. For one-dimensional channels (AFI) and intersecting channel structures (MFI), the Di,self invariably decreases with increasing qi. For zeolite structures that consist of cages separated by windows (FAU, CHA, DDR, LTA), the size of the windows is an important determinant. When the windows are wide (FAU), the Di,self decreases with qi for all molecules. If the windows are narrow (CHA, DDR and LTA), the Di,self often exhibits a sharp increase with qi, reaches a maximum and reduces to near-zero values at saturation. The sharpness with which Di,self increases with qi, is dictated by the degree of confinement at the window. Weakly confined molecules, such as Ne, do not exhibit an increase of Di,self with qi. [source] Octanuclear Oxothiomolybdate(V) Rings: Structure and Ionic-Conducting PropertiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2004Charlotte du Peloux Dr. Abstract A family of alkali salts of octanuclear oxothiomolybdate rings has been synthesized by crystallization of the [Mo8S8O8(OH)8{HMO5(H2O)}]3, (noted HMo8M3,; M=Mo, W) and [Mo8S8O8(OH)8(C2O4)]2, (noted Mo8ox2,) anions in an aqueous solution of ACl (A=Li, Na, K, Rb). Single-crystal X-ray diffraction experiments have been performed showing that the alkali salts exhibit a similar three-dimensional structure. Disordered alkali ions form columns to which the anionic rings are anchored. Ionic-conductivity measurements on pressed pellets have revealed two different behaviors. The lithium salts of HMo8M3, (M=Mo, W) are moderately good proton conductors at room temperature (,=10,5 S,cm,1) and the profile of conductivity as a function of relative humidity shows that the conductivity is due to surface-proton motion (particle-hydrate-type mechanism). On the other hand, the lithium salt of Mo8ox2, competes with the best crystalline lithium conductors at room temperature (,=10,3 S,cm,1), and 7Li NMR experiments confirm the mobility of the lithium ions along the one-dimensional channels of this material. [source] Syntheses and Crystal Structure of a New 3D Ag (I)-Fumaric Acid Framework, [Ag (hmt) (fma)1/2 · 2H2O]nCHINESE JOURNAL OF CHEMISTRY, Issue 6 2003Bi Wen-Hua Abstract A new silver (I) coordination polymer, [Ag(hmt) (fma)1/2 · 2H2O]n (1), (hmt = hexamethylenetetramine, fma = furmaric acid), was obtained by self-assembly of hmt, fma and AgNO3 in the mixed solvent of methanol, dichloromethane and water (CH3OH:CH2Cl2:H2O = 5:5:1), and characterized by X-ray diffraction analysis. Complex 1 belongs to orthorhombic space group Pbcn with cell parameters a = 1.72043(5) nm, b=1.19704(2) nm, c = 1.11685(3) nm, V = 2.30007(10) nm3, Z = 8, CCDC number: 194381. In complex 1, each hmt ligand acts as a ,3 -bridge to link three Ag(I) atoms and in turn every Ag(I) ion attaches to three hmt ligands to produce a 2D honeycomb network, which is further linked by the bidentate fma ligands to form a 3D noninterpenetrating open framework with one-dimensional channels being filled by guest molecules. 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