scholarly journals Solving Crystal Structures from Powder Diffraction Data

1985 ◽  
Vol 38 (3) ◽  
pp. 497 ◽  
Author(s):  
A Nørlund Christensen ◽  
MS Lehmann ◽  
M Nielsen
Keyword(s):  
High Resolution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Direct Methods ◽  
Powder Diffraction Data ◽  
Profile Data ◽  
X Ray ◽  
R Factor ◽  
Symmetric Structure ◽  
Acceptable Quality

High resolution powder data from both neutron and X-ray (synchrotron) sources have been used to estimate the possibility of direct structure determination from powder data. Two known structures were resolved by direct methods with neutron and X-ray data. With synchrotron X-ray data, the measured range of data was insufficient for a structure analysis, but the R-factor calculations showed the intensities extracted from the profile data to be of acceptable quality. The results were used to estimate the largest structure that might be solved using routine techniques. It was found that the limit would be near twenty atoms in the asymmetric part of a centro-symmetric structure.

The crystal structures of solvent-free alkali-metal squarates from powder diffraction data

2005 ◽  
Vol 220 (11) ◽  
Author(s):  
Robert E. Dinnebier ◽  
Hanne Nuss ◽  
Martin Jansen
Keyword(s):  
High Resolution ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Solvent Free ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray

AbstractThe crystal structures of solvent-free lithium, sodium, rubidium, and cesium squarates have been determined from high resolution synchrotron and X-ray laboratory powder patterns. Crystallographic data at room temperature of Li

Combined Rietveld and stereochemical restraint refinement of a protein crystal structure

1999 ◽  
Vol 32 (6) ◽  
pp. 1084-1089 ◽  
Author(s):  
R. B. Von Dreele
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Tertiary Structure ◽  
Protein Crystal ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Protein Crystal Structure

By combining high-resolution X-ray powder diffraction data and stereochemical restraints, Rietveld refinement of protein crystal structures has been shown to be feasible. A refinement of the 1261-atom protein metmyoglobin was achieved by combining 5338 stereochemical restraints with a 4648-step (dmin= 3.3 Å) powder diffraction pattern to give the residualsRwp= 2.32%,Rp= 1.66%,R(F2) = 3.10%. The resulting tertiary structure of the protein is essentially identical to that obtained from previous single-crystal studies.

Crystal structure determination of mebendazole form A using high‐resolution synchrotron x‐ray powder diffraction data

2010 ◽  
Vol 99 (4) ◽  
pp. 1734-1744 ◽  
Author(s):  
Fabio Furlan Ferreira ◽  
Selma Gutierrez Antonio ◽  
Paulo César Pires Rosa ◽  
Carlos de Oliveira Paiva‐Santos
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Powder Diffraction Data ◽  
X Ray

Structure of C15-, C17- and C19-mono-acid β-triacylglycerols

2001 ◽  
Vol 58 (1) ◽  
pp. 134-139 ◽  
Author(s):  
Robert B. Helmholdt ◽  
René Peschar ◽  
Henk Schenk
Keyword(s):  
High Resolution ◽  
Powder Diffraction ◽  
Layered Structure ◽  
Diffraction Data ◽  
Tuning Fork ◽  
Acyl Chain ◽  
Grid Search ◽  
Powder Diffraction Data ◽  
Chain Packing ◽  
X Ray

The crystal structures of β-1,2,3-tris(pentadecanoyl)glycerol (β-C15C15C15), β-1,2,3-tris(heptadecanoyl)glycerol (β-C17C17C17) and β-1,2,3-tris(nonadecanoyl)glycerol (β-C19C19C19) have been determined from high-resolution X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structures, respectively. As in β-1,2,3-tris(tridecanoyl)glycerol (β-C13C13C13) and the even-numbered mono-acid triacylglycerols, all three odd-numbered monoacid triacylglycerols crystallize in space group P\bar 1 with Z = 2 in an asymmetric tuning-fork conformation and have a lateral acyl chain packing resulting in a layered structure.

Crystal Structure of the Ternary Compound Sc6Cu24.1Al11.9

2016 ◽  
Vol 257 ◽  
pp. 26-29 ◽  
Author(s):  
Nastasia Klymentiy ◽  
Nataliya Semuso ◽  
Svitlana Pukas ◽  
Yaroslav O. Tokaychuk ◽  
Lev Akselrud ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Direct Methods ◽  
The Body ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Pearson Symbol ◽  
Icosahedral Clusters

The crystal structure of a new ternary aluminide of refined composition Sc6Cu24.1(2)Al11.9(2) was solved by direct methods from X-ray powder diffraction data. It belongs to the cubic space group Im-3, Pearson symbol cI176-8, a = 13.5337(5) Å. The structure of Sc6Cu24.1Al11.9 may be described as a packing of 16-vertex coordination polyhedra of the Sc atoms, which form icosahedral clusters around the origin and the center of the body-centered unit cell. The voids at the centers of the clusters are filled by Cu4 tetrahedra, disordered between two possible orientations. The structure is closely related to the structure types Ru3Be17 and Ce6Au27.6Sn6.8.

Structure of β-trimyristin and β-tristearin from high-resolution X-ray powder diffraction data

2001 ◽  
Vol 57 (3) ◽  
pp. 372-377 ◽  
Author(s):  
Arjen van Langevelde ◽  
René Peschar ◽  
Henk Schenk
Keyword(s):  
High Resolution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Grid Search ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Distance Restraints

The crystal structures of β-1,2,3-tritetradecanoylglycerol (β-trimyristin or β-MMM) and β-1,2,3-trioctadecanoylglycerol (β-tristearin or β-SSS) have been determined from high-resolution synchrotron X-ray powder diffraction data. Grid search and Rietveld refinement have been used to determine and refine the structure, respectively. Both substances crystallize in space group P\bar 1 with Z = 2. The unit-cell parameters for β-MMM are a = 12.0626 (6), b = 41.714 (1), c = 5.4588 (3) Å, α = 73.388 (4), β = 100.408 (5) and γ = 118.274 (4)°. For β-SSS the unit-cell parameters are a = 12.0053 (7), b = 51.902 (2), c = 5.4450 (3) Å, α = 73.752 (5), β = 100.256 (6) and γ = 117.691 (5)°. Soft-distance restraints have been applied to the molecules during refinement. For β-MMM the final Rp value obtained is 0.053 and for β-SSS the final Rp value is 0.041.

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