scholarly journals Crystal structures of eight mono-methyl alkanes (C26–C32)viasingle-crystal and powder diffraction and DFT-D optimization

IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 490-497 ◽  
Author(s):  
Lee Brooks ◽  
Michela Brunelli ◽  
Philip Pattison ◽  
Graeme R. Jones ◽  
Andrew Fitch
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Structural Parameters ◽  
Carbon Chain ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystalline Materials ◽  
Social Species ◽  
Greater Curvature ◽  
Fully Extended Conformation

The crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species,e.g.ants, waspsetc. The molecules were synthesized as pureSenantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66.All crystallize in space groupP21. Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10° from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials.

Applications of High-Resolution Powder X-Ray Diffraction

2007 ◽  
Vol 130 ◽  
pp. 7-14 ◽  
Author(s):  
Andrew N. Fitch
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
Powder Diffraction ◽  
X Rays ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Structural Characterisation ◽  
Pdf Analysis

The highly-collimated, intense X-rays produced by a synchrotron radiation source can be harnessed to build high-resolution powder diffraction instruments with a wide variety of applications. The general advantages of using synchrotron radiation for powder diffraction are discussed and illustrated with reference to the structural characterisation of crystalline materials, atomic PDF analysis, in-situ and high-throughput studies where the structure is evolving between successive scans, and the measurement of residual strain in engineering components.

Comparative evaluation of the March and generalized spherical harmonic preferred orientation models using X-ray diffraction data for molybdite and calcite powders

2005 ◽  
Vol 38 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Husin Sitepu ◽  
Brian H. O'Connor ◽  
Deyu Li
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Spherical Harmonic ◽  
Comparative Evaluation ◽  
Preferred Orientation ◽  
Composition Analysis ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray

Preferred crystallographic orientation,i.e.texture in crystalline materials powder diffraction data, can cause serious systematic errors in phase composition analysis and also in crystal structure determination. The March model [Dollase (1986).J. Appl. Cryst.19, 267–272] has been used widely in Rietveld refinement for correcting powder diffraction intensities with respect to the effects of preferred orientation. In the present study, a comparative evaluation of the March model and the generalized spherical harmonic [Von Dreele (1997).J. Appl. Cryst.30, 517–525] description for preferred orientation was performed with X-ray powder diffraction data for molybdite (MoO3) and calcite (CaCO3) powders uniaxially pressed at five different pressures. Additional molybdite and calcite powders, to which 50% by weight silica gel had been added, were prepared to extend the range of preferred orientations considered. The patterns were analyzed initially assuming random orientation of the crystallites and subsequently the March model was used to correct the preferred orientation. The refinement results were compared with parallel refinements conducted with the generalized spherical harmonic [Sitepu (2002).J. Appl. Cryst.35,274–277]. The results obtained show that the generalized spherical harmonic description generally provided superior figures-of-merit compared with the March model results.

On racemic and L-malates: a comparison of their crystal structures

2004 ◽  
Vol 219 (2) ◽  
Author(s):  
Michel Fleck ◽  
Ekkehart Tillmanns ◽  
Ladislav Bohatý ◽  
Peter Held
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Space Group ◽  
X Ray

AbstractThe crystal structures of eight different L-malates have been determined and refined from single-crystal X-ray diffraction data. The compounds are the monoclinic (space groupIn addition, for all the compounds, powder diffraction data were collected, analysed and submitted to the powder diffraction file (PDF).

Crystal Structures of New Compounds Na0.5Sm4.5Ti4O15 and Na0.5Eu4.5Ti4O15

2011 ◽  
Vol 415-417 ◽  
pp. 468-471
Author(s):  
Qiao Hong Yu ◽  
Zheng Fa Li ◽  
Yong Xiang Li ◽  
Ping Zhan Si ◽  
Jiang Ying Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ordinary Temperature ◽  
Europium Titanate ◽  
New Compounds

New compounds of sodium samarium titanate Na0.5Sm4.5Ti4O15and sodium europium titanate Na0.5Eu4.5Ti4O15were synthesized successfully by solid state reaction at 1300 oC and 1200 oC, respectively. The lattice parameters of Na0.5Sm4.5Ti4O15and Na0.5Eu4.5Ti4O15were determined at ordinary temperature by using X-ray powder diffraction method. Their Lattice types were determined, and their patterns were indexed. Polycrystalline X-ray diffraction data of sodium samarium titanate were listed. Differences of their crystal structures were analyzed and discussed.

New Insights into Hexacoordinated Silicon Complexes with 8- Oxyquinolinato Ligands: 1,3-Shift of Si-Bound Hydrocarbyl Substituents and the Influence of Si-Bound Halides on the 8-Oxyquinolinate Coordination Features

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1402-1418 ◽  
Author(s):  
Erik Wächtler ◽  
Alexander Kämpfe ◽  
Katrin Krupinski ◽  
Daniela Gerlach ◽  
Edwin Kroke ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Coordination Chemistry ◽  
Crystal Structures ◽  
Quantum Chemical ◽  
Poor Response ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
X Ray ◽  
Cp Mas Nmr

Abstract The transsilylation reaction between allyltrichlorosilane and 8-trimethylsiloxyquinoline in the molar ratio 1 : 3 yields the hexacoordinated silicon tris-chelate (oxinate)2Si(adho) (“oxinate” = 8- oxyquinolinate, “adho” = di-anion of 2-allyl-1,2-dihydro-8-oxyquinoline) comprising an SiO3N3 skeleton. The identity of this complex was established by single-crystal X-ray diffraction analysis and 29Si CP=MAS NMR spectroscopy of its chloroform solvate. Benzyltrichlorosilane and dibenzyldichlorosilane, comprising benzyl (Bn) as an “aromatically stabilized allyl moiety” did not undergo such rearrangement. Instead, the complexes (oxinate)2SiBnCl and (oxinate)2SiBn2 were obtained even upon using three molar equivalents of 8-trimethylsiloxyquinoline. We determined the crystal structure of a non-disordered bis-chelate (oxinate)2SiBnCl with Sibound hydrocarbyl and halogen substituents (the previously published (oxinate)2SiMeCl was disordered with alternative Me=Cl site occupancies). (Oxinate)2SiBnCl exhibits surprisingly poor response of the N-Si bonds to the different trans-disposed Si-X (X=Bn, Cl) bonds. For comparison and deeper insights into the coordination chemistry of oxinato silicon complexes with halide substituents, we determined the crystal structures of (oxinate)2SiPhCl·CHCl3, (oxinate)2SiCl2, (oxinate)2SiF2·1.5(CHCl3), and (8-oxyquinaldinate)2SiF2. Furthermore, the crystal structures of BnSiCl3 and Bn2SiCl2 (and its dibromo analog) are reported. The influence of the Si-C-C-C torsion angles of the benzyl group on the 29Si NMR shift of benzylsilanes (which is noticeably upfield with respect to analogous methyl silanes) was analyzed by quantum-chemical calculations.

Crystal structures and conformations of 1-α-D-xylofuranosylcytosine and its protonated form (HCl salt)

1981 ◽  
Vol 59 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Michael L. Post ◽  
Carol P. Huber ◽  
George I. Birnbaum ◽  
David Shugar
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Direct Method ◽  
Intramolecular Hydrogen Bonding ◽  
Protonated Form ◽  
X Ray Diffraction ◽  
Base Stacking ◽  
Torsion Angles ◽  
Cell Parameters ◽  
Intramolecular Hydrogen

The structures of 1-α-D-xylofuranosylcytosine, C9H13N3O5 (1), and its hydrochloride salt, C9H13N3O5•HCl (1•HCl), have been determined by X-ray diffraction from diffractometer data, using direct method techniques. Both compounds crystallize in the orthorhombic system with Z = 4. Space group and cell parameters are, for 1: P21212, a = 18.706, b = 8.127, c = 7.007 Å; and for 1 HCl::P21212, a = 16.800, b = 8.045, c = 8.897 Å. Refinement by block-diagonal least-squares calculations gave a final R of 0.033 on 873 reflections and 0.034 on 914 reflections for 1 and 1 HCl, respectively. The glycosyl torsion angles are in the anti domain, χCN = −25.1° (1) and −28.6° (1•HC1), and the sugar puckers are nearly pure [Formula: see text] and 3E (1•HCl) forms. The C(4′)—C(5′) rotamer is trans–gauche in both cases. No intramolecular hydrogen bonding occurs in the xylofuranosyl rings. Lattice packing in the crystal structures occurs via intermolecular hydrogen bonding, with base stacking in pairs about one of the 2-fold axes for the neutral form, and with no base-stacking interactions for the protonated form. The biological implications of the structure and conformation of α-nucleosides are examined.

scholarly journals Crystal structures of threeortho-substitutedN-acylhydrazone derivatives

2017 ◽  
Vol 73 (12) ◽  
pp. 1946-1951 ◽  
Author(s):  
H. Purandara ◽  
Sabine Foro ◽  
B. Thimme Gowda
Keyword(s):  
Hydrogen Bond ◽  
Crystal Structures ◽  
Nitro Group ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Torsion Angles ◽  
Molecular Conformations ◽  
Hydrogen Bond Interactions ◽  
Dimensional Network ◽  
Phenyl Rings

To explore the effect of the nature of substitutions on the structural parameters and hydrogen-bond interactions inN-acylhydrazone derivatives, the crystal structures of threeortho-substitutedN-acylhydrazone derivatives, namely (E)-N-{2-[2-(2-chlorobenzylidene)hydrazinyl]-2-oxoethyl}-4-methylbenzenesulfonamide, C16H16ClN3O3S (I), (E)-N-{2-[2-(2-methylbenzylidene)hydrazinyl]-2-oxoethyl}-4-methylbenzenesulfonamide, C17H19N3O3S (II), and (E)-N-{2-[2-(2-nitrobenzylidene)hydrazinyl]-2-oxoethyl}-4-methylbenzenesulfonamide, C16H16N4O5S (III), have been determined. The structures of the three compounds display similar molecular conformations and hydrogen-bond patterns. The hydrazone part of the molecule, C—C—N—N=C, is almost planar in all the compounds, with the C—C—N—N and C—N—N=C torsion angles being 179.5 (3) and 177.1 (3)°, respectively, in (I), −179.4 (2) and −177.1 (3)° in (II) and −179.7 (2) and 173.4 (2)° in (III). The two phenyl rings on either side of the chain are approximately parallel to each other. In the crystal, the molecules are linked to each otherviaN—H...O hydrogen bonds, forming ribbons withR22(8) andR22(10) ring motifs. The introduction of electron-withdrawing groups (by a chloro or nitro group) to produce compounds (I) or (III) results in C—H...O hydrogen-bonding interactions involving the sulfonyl O atoms of adjacent ribbons, forming layers parallel to theabplane in (I) or a three-dimensional network in (III). In (III), one O atom of the nitro group is disordered over two orientations with refined occupancy ratio of 0.836 (12):0.164 (12).

scholarly journals Crystal structures and the Hirshfeld surface analysis of (E)-4-nitro-N′-(o-chloro, o- and p-methylbenzylidene)benzenesulfonohydrazides

2018 ◽  
Vol 74 (12) ◽  
pp. 1710-1716
Author(s):  
Akshatha R. Salian ◽  
Sabine Foro ◽  
B. Thimme Gowda
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Monoclinic Crystal ◽  
Torsion Angles ◽  
Axis Direction ◽  
Hydrogen Bonding Interactions ◽  
Torsional Angles

The crystal structures of (E)-N′-(2-chlorobenzylidene)-4-nitrobenzenesulfonohydrazide, C13H10ClN3O4S (I), (E)-N′-(2-methylbenzylidene)-4-nitrobenzenesulfonohydrazide, C14H13N3O4S (II), and (E)-N′-(4-methylbenzylidene)-4-nitrobenzenesulfonohydrazide monohydrate, C14H13N3O4S·H2O (III), have been synthesized, characterized and their crystal structures determined to study the effects of the nature and sites of substitutions on the structural parameters and the hydrogen-bonding interactions. All three compounds crystallize in the monoclinic crystal system, with space group P21 for (I) and P21/c for (II) and (III). Compound (III) crystallizes as a monohydrate. All three compounds adopt an E configuration around the C=N bond. The molecules are bent at the S atom with C—S—N—N torsion angles of −59.0 (3), 58.0 (2) and −70.2 (1)° in (I), (II) and (III), respectively. The sulfonohydrazide parts are also non-linear, as is evident from the S—N—N—C torsional angles of 159.3 (3), −164.2 (1) and 152.3 (1)° in (I), (II) and (III), respectively, while the hydrazide parts are almost planar with the N—N=C—C torsion angles being −179.1 (3)° in (I), 176.7 (2)° in (II) and 175.0 (2)° in (III). The 4-nitro-substituted phenylsulfonyl and 2/4-substituted benzylidene rings are inclined to each other by 81.1 (1)° in (I), 81.4 (1)° in (II) and 74.4 (1)° in (III). The compounds show differences in hydrogen-bonding interactions. In the crystal of (I), molecules are linked via N—H...O hydrogen bonds, forming C(4) chains along the a-axis direction that are interconnected by weak C—H...O hydrogen bonds, generating layers parallel to the ac plane. In the crystal of (II), the amino H atom shows bifurcated N—H...O(O) hydrogen bonding with both O atoms of the nitro group generating C(9) chains along the b-axis direction. The chains are linked by weak C—H...O hydrogen bonds, forming a three-dimensional framework. In the crystal of (III), molecules are linked by Ow—H...O, N—H...Ow and C—H...O hydrogen bonds, forming layers lying parallel to the bc plane. The fingerprint plots generated for the three compounds show that for (I) and (II) the O...H/H...O contacts make the largest contributions, while for the para-substituted compound (III), H...H contacts are the major contributors to the Hirshfeld surfaces.

Synthesis and Structures of Simple (Silylmethyl)(methyl)ethers

2003 ◽  
Vol 58 (8) ◽  
pp. 759-763 ◽  
Author(s):  
Norbert W. Mitzel
Keyword(s):  
Crystal Structures ◽  
Structural Parameters ◽  
Structural Basis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Donor Acceptor

The compound Cl3SiCH2OCH3 was prepared by reacting ClCH2OCH3 with the Cl3SiH/NEt3 reagent. H3SiCH2OCH3 and F3SiCH2OCH3 were synthesized from Cl3SiCH2OCH3 by reduction with LiAlH4 and by fluorination with SbF3, respectively. The crystal structures of the low-melting compounds H3SiCH2OCH3 and F3SiCH2OCH3 were determined by X-ray diffraction of in situ grown crystals. Both compounds do not show any observable β -donor-acceptor interactions, but behave structurally like usual dialkylethers or silanes, as is obvious from the structural parameters in H3SiCH2OCH3 (<SiCO 108.4(3)-109.4(3)°, <COC 111.0(4)-111.6(4)°) and in F3SiCH2OCH3 (<SiCO 107.1(1), <COC 111.2(2)°). Earlier postulates of Si· · ·O interactions in compounds with SiCO units could thus not be confirmed on a structural basis.

Structures and X-ray diffraction patterns of compounds in the Sr–Nd–Cu–O system

1995 ◽  
Vol 10 (1) ◽  
pp. 56-66 ◽  
Author(s):  
Winnie Wong-Ng
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Comprehensive Review ◽  
X Ray ◽  
Diffraction Patterns ◽  
Ternary Oxides

A comprehensive review of phases found in the Sr–Nd–Cu–O system which contains the high Tc superconductor phase Sr1−xNdxCuO2 has been prepared. This paper summarizes the crystal structures reported in the literature and the X-ray powder diffraction patterns reported in the ICDD Powder Diffraction File (PDF). In order to supplement the PDF with new patterns, calculated X-ray powder diffraction patterns generated from reported structures are provided for five ternary oxides: Sr0.86Nd0.14CuO2, SrNdCuO3.5, Sr6Nd3Cu6O17, Sr2NdCu2O5.66, and Sr1.2Nd1.8Cu2O6.

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