Structure determination of the 1/1 α/β mixed lactose by X-ray powder diffraction

2005 ◽  
Vol 61 (4) ◽  
pp. 455-463 ◽  
Author(s):  
Jacques Lefebvre ◽  
Jean-François Willart ◽  
Vincent Caron ◽  
Ronan Lefort ◽  
Frédéric Affouard ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Size Effects ◽  
Room Temperature ◽  
Real Space ◽  
Hydroxyl Groups ◽  
Soft Constraints ◽  
Rietveld Refinements ◽  
X Ray ◽  
Mixed Compound

The mixed form of α/β lactose was obtained by heating amorphous α-lactose at 443 K. NMR spectroscopy determined the stoichiometry of this mixed compound to be 1/1. The X-ray powder diffraction pattern was recorded at room temperature with a sensitive curved detector (CPS 120). The structure was solved by real-space methods (simulated annealing) followed by Rietveld refinements with soft constraints on bond lengths and bond angles. The H atoms of the hydroxyl groups were localized by minimization of the crystalline energy. The cell of 1/1 α/β lactose is triclinic with the space group P1 and contains two molecules (one molecule of each anomer). The crystalline cohesion is achieved by networks of O—H...O hydrogen bonds. The width of the Bragg peaks is interpreted through a microstructural approach in terms of isotropic strain effects and anisotropic size effects.

Structure determination of the stable anhydrous phase of α-lactose from X-ray powder diffraction

2005 ◽  
Vol 61 (2) ◽  
pp. 185-191 ◽  
Author(s):  
Cyril Platteau ◽  
Jacques Lefebvre ◽  
Frederic Affouard ◽  
Jean-François Willart ◽  
Patrick Derollez ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
Structural Model ◽  
Hydroxyl Groups ◽  
Rietveld Refinements ◽  
X Ray ◽  
Hydrogen Bond Networks ◽  
Monte Carlo Simulated Annealing ◽  
Annealing Method

The stable anhydrous form of α-lactose has been obtained by the dehydration of α-lactose monohydrate in methanol. An X-ray powder diffraction pattern was recorded at room temperature with a laboratory diffractometer equipped with an INEL curved sensitive detector CPS120. The starting structural model of this form was found by a Monte-Carlo simulated annealing method. The structure was obtained through Rietveld refinements and the minimization of crystalline energy for the localization of the H atoms of the hydroxyl groups. Soft restraints were applied to bond lengths and angles. Networks of O—H...O hydrogen bonds account for the crystalline cohesion. A comparison is made between the hydrogen-bond networks of this form and those of the monohydrate and hygroscopic anhydrous forms of α-lactose.

Distorted chiolite crystal structures of α-Na5M3F14 (M=Cr,Fe,Ga) studied by X-ray powder diffraction

2003 ◽  
Vol 18 (2) ◽  
pp. 128-134 ◽  
Author(s):  
A. Le Bail ◽  
A.-M. Mercier
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Precise Characterization

The crystal structures of the chiolite-related room temperature phases α-Na5M3F14 (MIII=Cr,Fe,Ga) are determined. For all of them, the space group is P21/n, Z=2; a=10.5096(3) Å, b=7.2253(2) Å, c=7.2713(2) Å, β=90.6753(7)° (M=Cr); a=10.4342(7) Å, b=7.3418(6) Å, c=7.4023(6) Å, β=90.799(5)° (M=Fe), and a=10.4052(1) Å, b=7.2251(1) Å, c=7.2689(1), β=90.6640(4)° (M=Ga). Rietveld refinements produce final RF factors 0.036, 0.033, and 0.035, and RWP factors, 0.125, 0.116, and 0.096, for MIII=Cr, Fe, and Ga, respectively. The MF6 polyhedra in the defective isolated perovskite-like layers deviate very few from perfect octahedra. Subtle octahedra tiltings lead to the symmetry decrease from the P4/mnc space group adopted by the Na5Al3F14 chiolite aristotype to the P21/n space group adopted by the title series. Facile twinning precluded till now the precise characterization of these compounds.

Structure determination of L-arabinitol by powder X-ray diffraction

2012 ◽  
Vol 68 (4) ◽  
pp. 407-411 ◽  
Author(s):  
Patrick Derollez ◽  
Yannick Guinet ◽  
Frédéric Affouard ◽  
Florence Danède ◽  
Laurent Carpentier ◽  
...  
Keyword(s):  
Structural Model ◽  
Interatomic Bond ◽  
Hydroxyl Groups ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Monte Carlo Simulated Annealing ◽  
Diffraction Patterns ◽  
Annealing Method

Powder X-ray diffraction patterns of the commercial phase of L-arabinitol were recorded with a laboratory diffractometer. The starting structural model was found by a Monte-Carlo simulated annealing method. The final structure was obtained through Rietveld refinements with soft restraints on the interatomic bond lengths and bond angles. H atoms of hydroxyl groups were localized by minimization of the crystalline energy. The cell is triclinic with the space group P1 and contains two molecules. The crystalline cohesion is achieved by an important network of O—H...O hydrogen bonds.

Determination of crystal structures and tautomeric states of 2-ammoniobenzenesulfonates by laboratory X-ray powder diffraction

2015 ◽  
Vol 230 (9-10) ◽  
Author(s):  
Sándor L. Bekö ◽  
Christian Czech ◽  
Marcus A. Neumann ◽  
Martin U. Schmidt
Keyword(s):  
Dft Calculations ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Laboratory Data ◽  
Powder Diffraction Data ◽  
Dft Methods ◽  
Rietveld Refinements ◽  
X Ray ◽  
Polymorph Screening

AbstractThe crystal structures of 4-chloro-5-methyl-2-ammoniobenzenesulfonate and of the corresponding derivatives 4,5-dimethyl- and 4,5-dichloro-2-ammoniobenzenesulfonates have been determined from laboratory X-ray powder diffraction data. The tautomeric state of all three compounds could also be unequivocally determined from laboratory data, using careful Rietveld refinements. The tautomeric state was confirmed by IR spectroscopy. The compounds are neither isostructural to each other nor to the 5-chloro-4-methyl derivate, despite the similar size of the chloro and methyl substituents. The influence of the chloro and methyl substituents on the packing and on the thermal stability is demonstrated. All crystal structures were confirmed by dispersion-corrected DFT calculations. For the 4-chloro-5-methyl and the 4,5-dichloro derivatives the DFT calculations indicated that the observed polymorph should not be the thermodynamical one. However, no other polymorphs could be found in experimental polymorph screening, even using seeding with the corresponding isostructural phases. Obviously the DFT methods need further improvements.

X-ray powder diffraction structural characterization of Pb1 − x Ba x Zr0.65Ti0.35O3 ceramic

2007 ◽  
Vol 63 (5) ◽  
pp. 713-718 ◽  
Author(s):  
M. Mir ◽  
V. R. Mastelaro ◽  
P. P. Neves ◽  
A. C. Doriguetto ◽  
D. Garcia ◽  
...  
Keyword(s):  
Phase Transition ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Powder Diffraction Data ◽  
Rietveld Refinements ◽  
X Ray ◽  
Cubic Structure ◽  
Good Agreement

The structure of Pb1 − x Ba x Zr0.65Ti0.35O3 (PBZT) ceramic materials with 0.00 ≤ x ≤ 0.40 was studied using synchrotron X-ray powder diffraction data. According to the Rietveld refinements, the structure of PBZT ceramics with x = 0.00, 0.10 and 0.20 at room temperature was rhombohedral R3c. A phase transition from rhombohedral to cubic was observed at 543 and 463 K for x = 0.10 and 0.20, respectively. The refinement for the compositions x = 0.30 and x = 0.40 showed a cubic structure from 10 to 450 K, in good agreement with the dielectric properties of these samples.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

2021 ◽  
pp. 1-3
Author(s):  
Carina Schlesinger ◽  
Edith Alig ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Commercial Sample ◽  
One Dimensional ◽  
X Ray ◽  
Hydrogen Bond Pattern

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

Structural characterization of two K2SnX(PO4)3 (X=Fe,Yb) with langbeinite structure

2006 ◽  
Vol 21 (3) ◽  
pp. 214-219 ◽  
Author(s):  
Abderrahim Aatiq ◽  
Btissame Haggouch ◽  
Rachid Bakri ◽  
Youssef Lakhdar ◽  
Ismael Saadoune
Keyword(s):  
Solid State ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Cell Parameter ◽  
Rietveld Analysis ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Octahedral Sites ◽  
Parameter Values

Structures of two K2SnX(PO4)3(X=Fe,Yb) phosphates, obtained by conventional solid state reaction techniques at 950 °C, were determined at room temperature by X-ray powder diffraction using Rietveld analysis. The two materials exhibit the langbeinite-type structure (P213 space group, Z=4). Cubic unit cell parameter values are: a=9.9217(4) Å and a=10.1583(4) Å for K2SnFe(PO4)3 and K2SnYb(PO4)3, respectively. Structural refinements show that the two crystallographically independent octahedral sites (of symmetry 3) have a mixed Sn∕X (X=Fe,Yb) population although ordering is stronger in the Yb phase than in the Fe phase.

ChemInform Abstract: Determination of Complex Structures by Combined Neutron and Synchrotron X-Ray Powder Diffraction.

ChemInform ◽  
2010 ◽  
Vol 24 (2) ◽  
pp. no-no
Author(s):  
R. E. MORRIS ◽  
W. T. A. HARRISON ◽  
J. M. NICOL ◽  
A. P. WILKINSON ◽  
A. K. CHEETHAM
Keyword(s):  
Powder Diffraction ◽  
Complex Structures ◽  
X Ray

Spektralreines Bis(phthalocyaninato)protactinium(IV) / Spectroscopically Pure Bis(phthalocyaninato)protactinium(IV)

1980 ◽  
Vol 35 (5) ◽  
pp. 564-567 ◽  
Author(s):  
Franz Lux ◽  
Oskar F. Beck ◽  
Heinz Krauß ◽  
David Brown ◽  
Tze C. Tso
Keyword(s):  
Solid State ◽  
Temperature Profile ◽  
Powder Diffraction ◽  
Phthalic Acid ◽  
Room Temperature ◽  
X Ray ◽  
Derivative Spectroscopy ◽  
Solid State Spectrum

Abstract Spectroscopically pure PaPc2 has been prepared by reaction between PaI4 · 4 CH3CN and o-phthalic acid dinitrile in 1-chloronaphthalene followed by sublimation at 5 · 10-3 Pa in a temperature profile with three clearly defined zones (520 °C/350 °C/room temperature). This procedure gives a product almost completely free of H2Pc impurity which is known to have been present in previously reported complexes of the type AnPc2. Thus, the trace of H2Pc in the substance could only be detected by derivative spectroscopy. X-ray powder diffraction shows the compound to be isostructural with ThPc2 and UPc2. The ligand spectrum is typical of AnPc2 complexes, f-f Bands observed in a solid state spectrum provide additional proof that the compound is PaIV Pc2.

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