scholarly journals Structure determination of riboflavin by synchrotron high-resolution powder X-ray diffraction

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Mathieu Guerain ◽  
Frédéric Affouard ◽  
Charline Henaff ◽  
Catherine Dejoie ◽  
Florence Danède ◽  
...  
Keyword(s):  
High Resolution ◽  
Structural Model ◽  
European Synchrotron Radiation Facility ◽  
Stable Form ◽  
X Ray Diffraction ◽  
Pxrd Pattern ◽  
X Ray ◽  
Monte Carlo Simulated Annealing ◽  
Hydroxy Groups

The crystal structure of the stable form of vitamin B2 or riboflavin (C17H20N4O6) was solved using high-resolution powder X-ray diffraction (PXRD). The high-resolution PXRD pattern of riboflavin was recorded at room temperature at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated using a Monte Carlo simulated annealing method. The final structure was obtained through Rietveld refinement. The positions of the H atoms belonging to hydroxy groups were estimated from computational energy minimizations. The symmetry is orthorhombic with the space group P212121 and the following lattice parameters: a = 20.01308, b = 15.07337 and c = 5.31565 Å.

Ab initio structure determination of the hygroscopic anhydrous form of α-lactose by powder X-ray diffraction

2004 ◽  
Vol 60 (4) ◽  
pp. 453-460 ◽  
Author(s):  
Cyril Platteau ◽  
Jacques Lefebvre ◽  
Frederic Affouard ◽  
Patrick Derollez
Keyword(s):  
Structural Model ◽  
Interatomic Bond ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Ab Initio Structure ◽  
Monte Carlo Simulated Annealing ◽  
Hydroxy Groups ◽  
Annealing Method

Annealing of α-lactose monohydrate at 408 K yielded a mixture of this compound with hygroscopic anhydrous α-lactose. A powder X-ray diffraction pattern of this mixture was recorded at room temperature. The starting structural model of hygroscopic α-lactose was found by a Monte Carlo simulated-annealing method. The final structure was obtained through Rietveld refinements, with soft restraints on interatomic bond lengths and bond angles, and crystalline energy minimization to locate the H atoms of the hydroxy groups. The crystalline cohesion is achieved by networks of O—H...O hydrogen bonds that differ from those of the monohydrate phase. The width of the Bragg peaks is interpreted by a phenomenological microstructural approach in terms of isotropic size effects and anisotropic strain effects.

Structure determination of a new cocrystal of carbamazepine and DL-tartaric acid by synchrotron powder X-ray diffraction

2020 ◽  
Vol 76 (3) ◽  
pp. 225-230 ◽  
Author(s):  
Mathieu Guerain ◽  
Patrick Derollez ◽  
Luisa Roca-Paixão ◽  
Catherine Dejoie ◽  
Natália T. Correia ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Structural Model ◽  
European Synchrotron Radiation Facility ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Pxrd Pattern ◽  
X Ray ◽  
Monte Carlo Simulated Annealing ◽  
The Stability ◽  
Dynamics Simulations

The crystal structure of a new cocrystal of carbamazepine (systematic name: 5H-dibenzo[b,f]azepine-5-carboxamide, C15H12N2O) and DL-tartaric acid (C4H6O6), obtained by liquid-assisted grinding, was solved by powder X-ray diffraction (PXRD). The high-resolution PXRD pattern of this new phase was recorded at room temperature thanks to synchrotron experiments at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated by a Monte-Carlo simulated annealing method. The final structure was obtained through Rietveld refinement and an energy minimization simulation was used to estimate the H-atom positions. The stability of the proposed structure as a function of temperature was also assessed from molecular dynamics simulations. The symmetry is monoclinic (space group P21/c) and contains eight molecules per unit cell, namely, four DL-tartaric acid and four carbamazepine molecules.

Structure determination of phase II of the antifungal drug griseofulvin by powder X-ray diffraction

2018 ◽  
Vol 74 (3) ◽  
pp. 321-324 ◽  
Author(s):  
Aurélien Mahieu ◽  
Jean-François Willart ◽  
Mathieu Guerain ◽  
Patrick Derollez ◽  
Florence Danéde ◽  
...  
Keyword(s):  
Phase Ii ◽  
Structural Model ◽  
Interatomic Bond ◽  
Antifungal Drug ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Pxrd Pattern ◽  
X Ray ◽  
Monte Carlo Simulated Annealing

Two new crystalline polymorphs of the widely used antifungal drug griseofulvin (phases II and III), which originate from the crystallization of the melt, have been detected recently. The crystal structure of phase II of griseofulvin {systematic name: (2S,6′R)-7-chloro-2′,4,6-trimethoxy-6′-methyl-3H,4′H-spiro[1-benzofuran-2,1′-cyclohex-2-ene]-3,4′-dione}, C17H17ClO6, has been solved by powder X-ray diffraction (PXRD). The PXRD pattern of this new phase was recorded at room temperature using synchrotron radiation. The starting structural model was generated by a Monte Carlo simulated annealing method. The final structure was obtained through Rietveld refinement with soft restraints for interatomic bond lengths and angles, except for the aromatic ring, where a rigid-body constraint was applied. The symmetry is orthorhombic (space groupP212121) and the asymmetric unit contains two molecules.

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.

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.

Determination of twist angle of in-plane mosaic spread of GaN films by high-resolution X-ray diffraction

2003 ◽  
Vol 255 (1-2) ◽  
pp. 63-67 ◽  
Author(s):  
X.H. Zheng ◽  
H. Chen ◽  
Z.B. Yan ◽  
Y.J. Han ◽  
H.B. Yu ◽  
...  
Keyword(s):  
High Resolution ◽  
Twist Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mosaic Spread

Composition determination of β-(AlxGa1−x)2O3layers coherently grown on (010) β-Ga2O3substrates by high-resolution X-ray diffraction

2016 ◽  
Vol 9 (6) ◽  
pp. 061102 ◽  
Author(s):  
Yuichi Oshima ◽  
Elaheh Ahmadi ◽  
Stefan C. Badescu ◽  
Feng Wu ◽  
James S. Speck
Keyword(s):  
High Resolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Composition Determination

Structure determination of forms I and II of phenobarbital from X-ray powder diffraction

2005 ◽  
Vol 61 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Cyril Platteau ◽  
Jacques Lefebvre ◽  
Stephanie Hemon ◽  
Carsten Baehtz ◽  
Florence Danede ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Bragg Peak Profiles ◽  
Monte Carlo Simulated Annealing ◽  
Crystal Structural ◽  
Diffraction Patterns ◽  
Annealing Method

From pure powders of forms I and II of phenobarbital, X-ray diffraction patterns were recorded at room temperature. The starting crystal structural models were found by a Monte-Carlo simulated annealing method. The structures of the two forms were obtained through Rietveld refinements. Soft restraints were applied on bond lengths and bond angles, all H-atom positions were calculated. The cell of form I is monoclinic with the space group P21/n, Z = 12, Z′ = 3. Form II has a triclinic cell, with the space group P\bar 1, Z = 6, Z′ = 3. For both forms, the crystal cohesion is achieved by networks of N—H...O hydrogen bonds along [101]. The broadening of the Bragg peak profiles is interpreted in terms of isotropic strain effects and anisotropic size effects.

Determination of the Twist Angle of GaN Film by High Resolution X-ray Diffraction

2008 ◽  
Vol 1 ◽  
pp. 045004 ◽  
Author(s):  
Hongtao Li ◽  
Yi Luo ◽  
Lai Wang ◽  
Guangyi Xi ◽  
Yang Jiang ◽  
...  
Keyword(s):  
High Resolution ◽  
Twist Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gan Film
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