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Interlayer Distance (interlayer + distance)
Selected AbstractsOrganic Intercalation Material: Reversible Change in Interlayer Distances by Guest Release and Insertion in Sandwich-Type Inclusion Crystals of Cholic AcidCHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2005Kazunori Nakano Dr. Abstract Cholic acid (CA) forms inclusion crystals that have a sandwich-type lamellar structure constructed by the alternative stacking of host bilayers and guest layers. Five disubstituted benzenes, o -toluidine, m -fluoroaniline, o -chlorotoluene, o -bromotoluene, and indene, are accommodated in the two-dimensional void space between the host bilayers at 1:2 host,guest stoichiometries. Thermal gravimetric analysis of the inclusion crystals revealed that all the guest molecules, except o -toluidine, are released in two separate steps, indicating the formation of intermediate crystals after the first guest release. Adequate heat treatment of the four inclusion crystals induces release of half or three quarters of the guest molecules. X-ray diffraction patterns of the intermediate crystals revealed that the crystals have a bilayer structure the same as those of the common CA inclusion crystals. They have one-dimensional cavities, in which the guest molecules are included at a 1:1 or 2:1 host,guest stoichiometry. These facts indicate that the host bilayers move 1.6,4.5 Å perpendicular to the layer direction by desorption of the guest molecules. Furthermore, a reverse structural change is also achieved by absorption of the guest molecules to regenerate the starting sandwich-type inclusion crystals. This reversible change in the host bilayer by the guest sorption and desorption is a novel example of organic intercalation materials. [source] Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical ConductanceADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Hyeon-Jin Shin Abstract The conductivity of graphite oxide films is modulated using reducing agents. It is found that the sheet resistance of graphite oxide film reduced using sodium borohydride (NaBH4) is much lower than that of films reduced using hydrazine (N2H4). This is attributed to the formation of CN groups in the N2H4 case, which may act as donors compensating the hole carriers in reduced graphite oxide. In the case of NaBH4 reduction, the interlayer distance is first slightly expanded by the formation of intermediate boron oxide complexes and then contracted by the gradual removal of carbonyl and hydroxyl groups along with the boron oxide complexes. The fabricated conducting film comprising a NaBH4 -reduced graphite oxide reveals a sheet resistance comparable to that of dispersed graphene. [source] Cadmium(II) thio- and selenocyanate complexes of 3,3,-bis(1,2,4-triazol-4-yl)-1,1,-biadamantane, a ligand designed with an `extended nanodiamond' aliphatic platformACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Ganna A. Senchyk In the structures of the CdII pseudohalide coordination polymer poly[[diaquabis[,2 -3,3,-bis(1,2,4-triazol-4-yl)-1,1,-biadamantane-,2N1:N1,]cadmium(II)] dithiocyanate dihydrate], {[Cd(C24H32N6)2(H2O)2](NCS)2·2H2O}n, (I), and the isomorphous selenocyanate analogue, {[Cd(C24H32N6)2(H2O)2](NCSe)2·2H2O}n, (II), the CdII cations occupy inversion centres and have octahedral CdN4O2 environments, completed by four N atoms of the organic ligands [Cd,N = 2.316,(2) and 2.361,(2),Å for (I), and 2.313,(3) and 2.372,(3),Å for (II)] and two trans -coordinated aqua ligands [Cd,O = 2.3189,(15),Å for (I) and 2.323,(2),Å for (II)]. In each compound, the ligand displays a bidentate N1:N1, -bridging mode, connecting the metal centres at a distance of 14.66,Å into two-dimensional nets of (4,4)-topology, while the uncoordinated thio(seleno)cyanate anions reside inside the net cavities. Hydrogen bonding between the water molecules, anions and 1,2,4-triazole N atoms supports the tight packing, with an interlayer distance of 6.09,Å. [source] A new organically templated vanadium tellurite: (H2dien)[(VO2)(TeO3)]2·2H2O (dien is diethylenetriamine)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Xihe Huang A new organically templated vanadium tellurite, poly[2,2,-iminodiethanaminium [hexa-,2 -oxido-tetraoxidoditellurium(IV)divanadium(V)] dihydrate], {(C4H15N3)[Te2V2O10]·2H2O}n, features the interconnection of distorted [VO5] trigonal bipyramids by bridging [TeO3] pyramids, leading to a two-dimensional corrugated anionic layer with an interlayer distance of about 13.47,Å. The interlayer space is occupied by doubly protonated diethylenetriamine cations (H2dien) and guest water molecules. The two terminal amino groups of H2dien are protonated, while the middle amino group, located on a twofold rotation axis, is not protonated. All the three amino groups and water molecules are involved in hydrogen-bonding interactions. The compound represents a new member in the series (H2am)[(VO2)(TeO3)]2·xH2O, where H2am represents a doubly protonated diamine. Similarities and differences between the structures of members of the series are discussed. [source] Dipotassium trimanganese(II) tetrakis(hydrogenphosphite), K2[Mn3(HPO3)4]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Farida Hamchaoui The title compound is a new mixed alkali/3d metal phosphite. It exhibits a layered structure formed by linear Mn3O12 trimer units which contain face-sharing MnO6 octahedra interconnected by (HPO3)2, phosphite oxoanions. The K+ cations located between the anionic [Mn3(HPO3)4]2, sheets are ninefold coordinated. The presence of the alkaline ion leads to the highest symmetry and shortest interlayer distance compared with two previous compounds showing the same anionic framework and having ammonium salts as cations. The compound crystallizes in the space group Rm, with two crystallographically independent Mn atoms occupying sites of m and 3m symmetry. All the other atoms, except for the phosphite O atoms, are located on special positions with 3m symmetry. [source] "Breathing" in Adsorbate-Responsive Metal Tetraphosphonate Hybrid MaterialsCHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2009Rosario M. Abstract Breathe easy: Reversible H2O and NH3 gas uptake by 2D calcium tetraphosphonates (see figure) is accompanied by framework structural changes similar to those previously reported for some carboxylate-based hybrids. This breathing mechanism is accompanied by a volume increase of 55,%, while maintaining the topology and crystallinity of the material. The structures of various layered calcium tetraphosphonates (CaH6DTMP; H8DTMP=hexamethylenediamine tetrakis(methylenephosphonic acid)), have been determined. Starting from CaH6DTMP,2H2O, thermal treatment and subsequent exposure to NH3 and/or H2O vapors led to four new compounds that showed high storage capacity of guest species between the layers (up to ten H2O/NH3 molecules) and a maximum volume increase of 55,%. The basic building block for these phosphonates consists of an eight-membered ring chelating Ca2+ through two phoshonate groups, and the organic ligand is located within the layers, which are held together by hydrogen bonds. The structural analysis revealed that the uptake/removal of guest species (H2O and NH3) induces significant changes in the framework not only by changing the interlayer distances but also through important conformational changes of the organic ligand. An anisotropic breathing motion could be quantified by the changes of the unit-cell dimensions and ligand arrangements in four crystalline derivatives. Complete characterization revealed the existence of interconversion reactions between the different phases upon gas uptake and release. The observed behavior represents, to the best of our knowledge, the first example of a breathing-like mechanism in metal phosphonates that possess a 2D topology. [source] | ||||||||||