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Single Crystal Structure Analysis (single + crystal_structure_analysis)
Selected AbstractsSynthesis, Structure and Emission Properties of Spirocyclic Benzofuranones and Dihydroindolones: A Domino Insertion,Coupling,Isomerization, Diels,Alder Approach to Rigid FluorophoresCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2008Daniel Abstract An alkynoyl ortho -iodo phenolester or alkynoyl ortho -iodo anilides and propargyl allyl ethers react under Sonogashira coupling conditions in the sense of an insertion,coupling,isomerization,Diels,Alder hetero domino reaction to furnish (tetrahydroisobenzofuran)-spirobenzofuranones and -spirodihydroindolones in good yields. Many representatives can be crystallized and single crystal structure analyses display steric and electronic substituent effects on the torsional angles of the terminal (hetero)aryl groups and the central cis,trans -butadiene fragment. DFT computations reveal that in the final pericyclic step the Diels,Alder termination is by far thermodynamically and kinetically favored over a possible Claisen rearrangement. Compounds of this new class of spirocyclic compounds possess large Stokes shifts and fluoresce intensively with blue over green to orange colors. As a consequence of the spirocyclic rigidity fluorescence lifetimes and quantum yields are rather high in some cases. Alkinoyl ortho -iodphenolester oder Alkinoyl ortho -iodanilide und Propargylallylether reagieren unter den Bedingungen der Sonogashira-Kupplung im Sinne einer Insertions,Kupplungs,Diels,Alder-Hetero-Domino-Reaktion zu (Tetrahydroisobenzofuran)-spirobenzofuranonen bzw. -spirodihydroindolonen in guten Ausbeuten, von denen viele kristallisiert werden konnten. Die Einkristallstrukturanalysen offenbaren sterische und elektronische Substituenteneffekte auf die Torsionswinkel der terminalen (Hetero)arylgruppen und des zentralen cis,trans -Butadienfragments. DFT-Rechnungen zeigen, dass im letzten pericyclischen Schritt die Diels,Alder-Reaktion gegenüber einer möglichen Claisen-Umlagerung bei weitem thermodynamisch und kinetisch begünstigt ist. Viele Verbindungen dieser neuen Spirocyclenklasse besitzen große Stokes-Verschiebungen und fluoreszieren intensive mit blauer, grüner oder oranger Farbe. Als Folge der spirocyclischen Rigidität sind in einigen Fällen die Fluoreszenzlebensdauern und Quantenausbeuten relative hoch. [source] The First Metal-Oxo Cluster Containing Lithium and BismuthEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2006Michael Mehring Abstract The reaction of [Bi(OtBu)3] with LiOSiMe3 gave the heterobimetallic bismuth-oxo cluster [Bi3Li5(,5 -O)2(,3 -OSiMe3)2(,3 -OtBu)2(,2 -OtBu)6] (1) after elimination of Me3SiOSiMe3. The cage compound 1 is the first example of a mixed-metal alkoxide/siloxide composed of lithium and bismuth. Crystals of 1·2 C7H8 and 1·1.5 THF suitable for X-ray single crystal structure analysis were obtained by crystallisation from toluene and THF, respectively. Both solvates crystallise in the orthorhombic space group Pmmn with Z = 2. The lattice constants are a = 16.267(3) Å, b = 17.126(3) Å and c = 12.155(2) Å (1·2 C7H8) and a = 16.353(2) Å, b = 17.156(1) Å and c = 12.256(1) Å (1·1.5 THF). In both compounds the solvent molecules occupy channels along the c -axis. The basic molecular unit is best described as a face-sharing double cubane [BiLi5(,4 -O)2(,3 -OSiMe3)2(,3 -OtBu)2] which is coordinated by two [Bi(OtBu)3] molecules. The compound is kinetically labile in solution and readily decomposes in 1,1,2,2-tetrachloroethane with elimination of 1,1,2-trichloroethylene. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Polymorphism and pseudopolymorphism of salicaine and salicaine hydrochloride crystal polymorphism of local anaesthetic drugs, part VJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2006A.C. Schmidt Abstract The local anaesthetic drug salicaine hydrochloride (hydroxytetracaine hydrochloride, 4-butylamino-2-hydroxybenzoic acid 2-dimethylaminoethyl ester hydrochloride, SLCHC) and the free-base salicaine (SLC) were characterized by thermal analysis, vibrational and solid-state NMR-spectroscopy, X-ray powder diffraction, X-ray single crystal structure analysis, and water vapor sorption analysis. Additionally, the crystal structures of the anhydrate mod. II° (monoclinic, space group P21/n), the hydrated mod. I (triclinic, space group ), and of the free base (SLC) in the form of the hemihydrate (triclinic, space group ) are discussed. Mod. II° of the polymorphic SLCHC is the thermodynamically stable form at room temperature and is present in commercial products mostly contaminated with a hydrated form that is isomorphic with mod. I. Mod. II° crystallizes from most organic solvents and from the melt below 110°C. Mod. I crystallizes from the melt at temperatures above 110°C, and additionally appears on dehydration of the hydrated mod. I. A third polymorph monotropically related to mod. II° was found by freeze-drying. The free-base SLC was found to crystallize from ethanol/water as a triclinic hemihydrate. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:1097,1113, 2006 [source] Raman spectroscopic study of the uranyl phosphate mineral dumontite Pb2 [(UO2)3O2(PO4)2]·5H2 OJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2009Ray L. Frost Abstract Raman spectra of dumontite were measured at 298 and 77 K. Observed bands were attributed to the stretching and bending vibrations of uranyl and phosphate units and OH stretching vibrations of water molecules. U,O bond lengths in uranyls and approximate O,H···O bond lengths were calculated. The values of the U,O bond lengths are in agreement with the data from the single crystal structure analysis of dumontite. Copyright © 2008 John Wiley & Sons, Ltd. [source] Raman spectroscopic study of the uranyl selenite mineral marthozite Cu[(UO2)3(SeO3)2O2]·8H2OJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2008Ray L. Frost Abstract The mineral marthozite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 K. The bands at 812 and 797 cm,1 were assigned to the symmetric stretching modes of the (UO2)2+ and (SeO3)2, units, respectively. These values gave the calculated UO bond lengths in uranyl of 1.799 and/or 1.814 Å. Average UO bond length in uranyl is 1.795 Å, inferred from the X-ray single crystal structure analysis of marthozite by Cooper and Hawthorne. The broad band at 869 cm,1 was assigned to the ,3 antisymmetric stretching mode of the (UO2)2+ (calculated UO bond length 1.808 Å). The band at 739 cm,1 was attributed to the ,3 antisymmetric stretching vibration of the (SeO3)2, units. The ,4 and the ,2 vibrational modes of the (SeO3)2, units were observed at 424 and 473 cm,1. Bands observed at 257, and 199 and 139 cm,1 were assigned to OUO bending vibrations and lattice vibrations, respectively. OH···O hydrogen bond lengths were inferred using Libowiztky's empirical relation. The infrared spectrum of marthozite was studied for complementation. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||