Novel synthetic alkali‐yttrium silicates with a new microporous mixed framework topology: (Rb,Cs)9Y7Si24O63 and isotypic Rb9Y7Si24O63

Prismatic colourless crystals of the two novel, isotypic title compounds were obtained by the flux growth technique. The crystal structures have been determined from single‐crystal intensity data in space group R 3 with a = 28.819(4) / 28.799(4), c = 13.916(3) / 13.864(3) Å, V = 10009(3) / 9958(3) ų, Z = 6, R (F) = 4.99 / 6.44%, respectively. They represent a novel structure type with microporous character. The framework is built from six‐membered silicate rings (approximate UDUDUD orientation) containing isolated YO₆ octahedra and compressed “six‐membered rings”, which in fact build a spiral of corner‐sharing SiO₄ tetrahedra. Approximately parallel to [111] run two different irregular channels hosting the Rb/Cs and Rb atoms. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal and molecular structures of 1-(2-carboxypropan-2-ylamino)-3-(1-naphthyloxy) propan-2-ol (1) (C17H21NO4) and 1-(2-carbamoyl propan-2-ylamino)-3-(1-naphthyloxy) propan-2-ol (2) (C17H22N2O3)

The crystal structures of two new-adrenergic antagonists, derivatives of propranolol containing 2-methylalanine fragment are described in this paper. The space groups and unit-cell parameters are: compound1 (C₁₇H₂₁NO₄): monoclinic, space groupP2₁/n,a=5.787(1),b=18.703(4),c=23.526(5)Å,=96.49(2)°; compound2 (C₁₇H₂₂N₂O₃): triclinic, space groupP¯1,a=8.321(1),b=10.121(1),c=10.368(1)Å,=109.49(1)°,=90.49(1)°, =103.48(1)°. The structures were solved by direct methods and refined with full matrix least-squares techniques toR indices of 0.055 and 0.049, respectively. The molecules of compound1 exist in the crystal as dual ions. The molecules of compound2 are compact and their external chain is twisted in a characteristic way (similar to that found in peptides).     

Crystal and molecular structures of 1-(2-iso butylylcarbamoyl propan-2-ylamino) 3-(1-naphthyloxy)propan-2-ol hydrochloride (1) (C21H31N2O3Cl) and 1-(2-isobutyloxycarbonylo propan-2-ylamino) 3-(1-naphthyloxy)propan-2-ol hydrochloride (2) (C21H30NO4Cl)

This paper shows the crystal structures of two new-adrenergic antagonists, derivatives of propranolol, which were determined with three-dimensional x-ray diffraction data. The space groups and unit-cell parameters are: compound1 (C₂₁H₃₁N₂O₃Cl) monoclinic space groupP2₁/c,a=20.523(4),b=6.909(2),c=15.950(2) Å,=105.03(1)°; compound2 (C₂₁H₃₁NO₄Cl) monoclinic space groupP2₁/c,a=6.364(2),b=36.043(8),c=10.149(1) Å,=104.48(2)°. The structures were solved with direct methods, and refined with full-matrix least-squares techniques toR indices of 0.059 and 0.067, respectively. The-CH(OH)-CH₂-NH-sections of the side chains show the conformation approximate togauche.     

The synthesis and X-ray structural studies of 2-cholesteryl-2-thio-1,3,2-oxathiaphospholane and 2-cholesteryl-2-thio-1,3,2-dithiaphospholane

Two thiophospholane derivatives of cholesterol: 2-cholesteryl-2-thio-1,3,2-oxathiaphospholane (1) and 2-cholesteryl-2-thio-1,3,2-dithiaphospholane (2) were synthesized as new reagents for introducing a cholesteryl moiety at the 5-end of oligonucleotidesvia the phosphorothioate or phosphorodithioate bond. Compounds1 and2 were subjected to structural studies by X-ray methods. Both compounds crystallized in the orthorhombic system, space group P2₁2₁2₁,1 witha=6.283(1) Å,b=12.067(1) Å,c=38.983(3) Å,2 witha=6.371(1) Å,b=11.971(1) Å andc=39.502(3) Å. The five-membered heterocyclic rings of both compounds attain a half-chair conformation in the solid state. In structures of1 and2 a disorder of some atoms is observed. The absolute configuration at the phosphorus atom in1 of the components of diastereoisomeric mixture has been established.     

Evaluation of thermal properties of MMCp composites with silver alloy matrix

Journal of Thermal Analysis and Calorimetry - Silver, silver alloys, and composites with silver matrix are used mainly as electric contacts, circuit-breakers, and slide bearings. Contacts working...     

Dynamic response of gold nanoparticle chemiresistors to organic analytes in aqueous solution

We investigate the response dynamics of 1-hexanethiol-functionalized gold nanoparticle chemiresistors exposed to the analyte octane in aqueous solution. The dynamic response is studied as a function of the analyte-water flow velocity, the thickness of the gold nanoparticle film and the analyte concentration. A theoretical model for analyte limited mass-transport is used to model the analyte diffusion into the film, the partitioning of the analyte into the 1-hexanethiol capping layers and the subsequent swelling of the film. The degree of swelling is then used to calculate the increase of the electron tunnel resistance between adjacent nanoparticles which determines the resistance change of the film. In particular, the effect of the nonlinear relationship between resistance and swelling on the dynamic response is investigated at high analyte concentration. Good agreement between experiment and the theoretical model is achieved.     

Solid State Conformation of and the Anomeric Effect in Conformationally Labile and Rigid 2-Thiophosphoryl and 2-Selenophosphoryl Substituted 1,3-Ditianes

Abstract

Conformation and geometry of 2-uophosphoryl and 2-selenophosphoryl 1,3-ditianes is determined by several stereoelectronic and steric efects [1]. The crystal and molecularstrustures of the six compouds shown below have been determined by X-ray methods. The differences in the coresponding bond distances and selected structural parameters for all these compounds are discussed in the context of anomeric effect.     

Asymmetric Cyclopropanation of Optically Active Vinyl Sulfoxides: A New Synthetic Approach to Biologically Active Compounds

Abstract

The influence of adjacent substituents on stereochemical course of cyclopropanation of vinyl sulfoxides with stabilized and nonstabilized ylides, as well as dependence on reaction conditions, was investigated. Application of optically active cyclopropanes obtained in the synthesis of conformationally constrained analogs of L-glutamic acid, the useful pharmacological tools in investigation of excitatory amino acid receptors, is presented.     

Synthesis of N-(2-(Methylamino)ethyl) Derivatives of 2H-Phthalazin-1-ones

A series of new alkyl, tosyl, acetyl, and tert-butoxycarbonyl derivatives of 2-(2-aminoethyl)-phthalazinones were efficiently synthesized by reaction of lactams with N-Boc-, N-acetyl-, or N,O-ditosyl derivatives of N-methylethanolamine in the presence of MeONa or under Mitsunobu reaction conditions. Selected compounds were converted into corresponding 2-[2-(methylamino)ethyl]phthalazinones in good yields.