Synthesis and crystal-structure determination of fibrillar methylammonium trimolybdate hydrate

2007 ◽  
Vol 22 (3) ◽  
pp. 241-245 ◽  
Author(s):  
B. Włodarczyk-Gajda ◽  
A. Rafalska-Łasocha ◽  
W. Łasocha
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Synthesis Method ◽  
Diffraction Method ◽  
Orthorhombic Space Group ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Novel Synthesis

A novel synthesis method of fibrillar trimolybdates with the use of Ag2Mo3O10∙2H2O as a precursor has been used successfully to synthesize methylammonium trimolybdate, (CH3NH3)2Mo3O10∙H2O. The crystal structure of this compound was determined by X-ray powder diffraction method and refined by the Rietveld method. The compound is orthorhombic, space group Pnma (62), with a=11.241(3), b=7.585(1), and c=15.516(4) Å. The redetermined crystal structure of the precursor and the structure of the title compound are compared and discussed.

scholarly journals Magnetically Oriented Powder Crystal to Indexing and Structure Determination

2014 ◽  
Vol 70 (a1) ◽  
pp. C1560-C1560
Author(s):  
Fumiko Kimura ◽  
Wataru Oshima ◽  
Hiroko Matsumoto ◽  
Hidehiro Uekusa ◽  
Kazuaki Aburaya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Powder Diffraction ◽  
Diffraction Method ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Lattice Parameters

In pharmaceutical sciences, the crystal structure is of primary importance because it influences drug efficacy. Due to difficulties of growing a large single crystal suitable for the single crystal X-ray diffraction analysis, powder diffraction method is widely used. In powder method, two-dimensional diffraction information is projected onto one dimension, which impairs the accuracy of the resulting crystal structure. To overcome this problem, we recently proposed a novel method of fabricating a magnetically oriented microcrystal array (MOMA), a composite in which microcrystals are aligned three-dimensionally in a polymer matrix. The X-ray diffraction of the MOMA is equivalent to that of the corresponding large single crystal, enabling the determination of the crystal lattice parameters and crystal structure of the embedded microcrytals.[1-3] Because we make use of the diamagnetic anisotropy of crystal, those crystals that exhibit small magnetic anisotropy do not take sufficient three-dimensional alignment. However, even for these crystals that only align uniaxially, the determination of the crystal lattice parameters can be easily made compared with the determination by powder diffraction pattern. Once these parameters are determined, crystal structure can be determined by X-ray powder diffraction method. In this paper, we demonstrate possibility of the MOMA method to assist the structure analysis through X-ray powder and single crystal diffraction methods. We applied the MOMA method to various microcrystalline powders including L-alanine, 1,3,5-triphenyl benzene, and cellobiose. The obtained MOMAs exhibited well-resolved diffraction spots, and we succeeded in determination of the crystal lattice parameters and crystal structure analysis.

Crystal Structure of the New Compound NdFeSb3

2007 ◽  
Vol 353-358 ◽  
pp. 3043-3046 ◽  
Author(s):  
Ping Li Qin ◽  
Liang Qin Nong ◽  
Ji Liang Zhang ◽  
Hai Qing Qin ◽  
Jiang Ping Liao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Type ◽  
Lattice Parameters ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The crystal structure of a new compound NdFeSb3 has been determined by X-ray powder diffraction using the Rietveld method. The compound crystallizes in the orthorhombic, space group Pbcm (No.57) with the CeNiSb3 structure type and lattice parameters a=1.26828(2)nm, b=0.61666(2)nm, c=1.81867(4) nm, z=12 and Dcalc=7.917g/cm3.

Synthesis and crystal structure of Co2(OH)2CO3 by Rietveld method

2010 ◽  
Vol 25 (S1) ◽  
pp. S7-S10 ◽  
Author(s):  
Shunli Wang ◽  
Guanglie Lü ◽  
Weihua Tang
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Cobalt Hydroxide ◽  
Site Symmetry ◽  
Powder Diffraction Data ◽  
Monoclinic System ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Oxygen Atoms

A new cobalt hydroxide carbonate Co2(OH)2CO3 was successfully synthesized by a hydrothermal method. The compound is isomorphous with malachite [Cu2(OH)2CO3] and crystallizes in a monoclinic system [space group P21/a (No. 14); a=9.448(5) Å, b=12.186(9) Å, c=3.188(4) Å, β=98.593°, V=367.143(9) Å3, Z=4, and Dc=3.786(9) g/cm3]. Crystal structure of Co2(OH)2CO3 was refined by the Rietveld method with RP=4.3%, RWP=5.7%, Rexp=5.1%, RB=1.74%, and S=1.117 on the basis of the X-ray powder diffraction data. The crystal structure of Co2(OH)2CO3 obtained by the Rietveld refinement shows that all species Co2+, CO32−, and OH− ions occupy C1 site symmetry. Two crystallographically different Co2+ and OH− ions and one type CO32− ion exist in the lattice. Co(1) is coordinated to two oxygen atoms from CO32− ions and two OH− ions; Co(2) is coordinated to two oxygen atoms from CO32− ions and four OH− ions, thus forming a distorted octahedron with (4+2) coordination.

Structure determination of diclofenac in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data

2004 ◽  
Vol 37 (2) ◽  
pp. 288-294 ◽  
Author(s):  
Nongnuj Muangsin ◽  
Malee Prajuabsook ◽  
Pitiporn Chimsook ◽  
Nuanphun Chantarasiri ◽  
Krisana Siraleartmukul ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Chitosan Matrix

The structure determination of diclofenac embedded in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data is demonstrated. It reveals that sodium diclofenac, the starting material in the preparation of a controlled-release diclofenac-containing chitosan matrix, changes to diclofenac acid in space groupC2/cin the matrix. Simple methods were employed for handling the sample to obtain X-ray powder diffraction data of sufficiently high quality for the determination of the crystal structure of diclofenac embedded in chitosan. These involved grinding and sieving several times through a micro-mesh sieve to obtain a suitable particle size and a uniformly spherical particle shape. A traditional technique for structure solution from X-ray powder diffraction data was applied. The X-ray diffraction intensities were extracted using Le Bail's method. The structure was solved by direct methods from the extracted powder data and refined using the Rietveld method. For comparison, the single-crystal structure of the same drug was also determined. The result shows that the crystal structure solved from conventional X-ray powder diffraction data is in good agreement with that of the single crystal. The deviations of the differences in bond lengths and angles are of the order of 0.030 Å and 0.639°, respectively.

scholarly journals Synthesis and crystal structure determination of the new olivine-type compound Mn2SnSe4

2019 ◽  
Vol 66 (1) ◽  
pp. 30
Author(s):  
C. Chacón ◽  
P. Delgado-Niño ◽  
G.E. Delgado
Keyword(s):  
Rietveld Method ◽  
Close Packing ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Orthorhombic Space Group ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Olivine Structure

The Mn2SnSe4 compound was synthesized by the melt and annealing technique and its structure was refined by the Rietveld method using X-ray powder diffraction data. This compound crystallizes in the olivine-type structure with unit cell parameters a = 12.9028(2) Å, b = 7.9001(1) Å, c = 6.5015(1) Å, V = 662.72(2) Å3 in the orthorhombic space group Pnma (Nº 62). This olivine structure can be described from a hexagonal close-packing of selenium atoms where manganese atoms occupy ½ of the octahedral sites while thin atoms lay in ⅛ of the tetrahedra.

Crystal structure determination of molecular compounds from conventional powder diffraction data: Trimeric silver(I) 3,5-dimethylpyrazolate

1998 ◽  
Vol 13 (1) ◽  
pp. 35-40 ◽  
Author(s):  
N. Masciocchi ◽  
P. Cairati ◽  
A. Sironi
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Laboratory Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Difference Fourier ◽  
Molecular Compounds ◽  
Bidentate Mode

In the absence of single crystals, silver(I) 3,5-dimethylpyrazolate, [Ag(dmpz)]3, has been structurally characterized by ab initio X-ray powder diffraction, using conventional laboratory data. Its crystals are triclinic, P1¯, with a=8.0876(10), b=11.1204(13), c=11.6136(16) Å, α=68.293(6), β=78.350(7), and γ=81.243(6)°. The structure has been solved by Patterson, difference Fourier, and geometrical modeling, and ultimately refined by the Rietveld method down to Rp=0.068, Rwp=0.085, and RF=0.055, for 4300 observations in the 17<2θ<103° range. Each molecule consists of a cyclic, trimeric assembly of Ag(dmpz) fragments, with the dmpz ligand bridging, in the exo-bidentate mode, nonbonded Ag…Ag edges.

Rietveld refinement of the crystal structure of α-CoSO4

1993 ◽  
Vol 8 (1) ◽  
pp. 54-56 ◽  
Author(s):  
Peter C. Burns ◽  
Frank C. Hawthorne
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The crystal structure of α-CoSO4 has been refined by the Rietveld method from X-ray powder diffraction data. The structure is orthorhombic, space group Pnma, a = 8.6127(4), b = 6.7058(3), c = 4.7399(2) Å, V = 273.75(3) Å3. Final RB = 2.41%, RP = 5.24%, RWP=6.66%, RWP (expected) =5.74% (WP =weighted profile). The structure consists of edge-sharing octahedral chains parallel to [010] interconnected by SO4 tetrahedra.

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.

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