Structure of Ca(BD4)2β-Phase from Combined Neutron and Synchrotron X-ray Powder Diffraction Data and Density Functional Calculations

2008 ◽  
Vol 112 (27) ◽  
pp. 8042-8048 ◽  
Author(s):  
F. Buchter ◽  
Z. Łodziana ◽  
A. Remhof ◽  
O. Friedrichs ◽  
A. Borgschulte ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
X Ray

Powder X-ray diffraction of Metastudtite, (UO2)O2(H2O)2

2016 ◽  
Vol 31 (1) ◽  
pp. 71-72 ◽  
Author(s):  
Mark A. Rodriguez ◽  
Philippe E. Weck ◽  
Joshua D. Sugar ◽  
Thomas J. Kulp
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
First Principles ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Unit Cells

There has been some confusion in the published literature concerning the structure of Metastudtite (UO2)O2(H2O)2 where differing unit cells and space groups have been cited for this compound. Owing to the absence of a refined structure for Metastudtite, Weck et al. (2012) have documented a first-principles study of Metastudtite using density functional theory (DFT). Their model presents the structure of Metastudtite as an orthorhombic (space group Pnma) structure with lattice parameters of a = 8.45, b = 8.72, and c = 6.75 Å. A Powder Diffraction File (PDF) database entry has been allocated for this hypothetical Metastudtite phase based on the DFT modeling (see 01-081-9033) and aforementioned Dalton Trans. manuscript. We have obtained phase pure powder X-ray diffraction data for Metastudtite and have confirmed the model of Weck et al. via Rietveld refinement (see Figure 1). Structural refinement of this powder diffraction dataset has yielded updated refined parameters. The new cell has been determined as a = 8.411(1), b = 8.744(1), and c = 6.505(1) Å; cell volume = 478.39 Å3. There are only subtle differences between the refined structure and that of the first-principles model derived from DFT. Notably, the b-axis is significantly contracted in the final refinement as compared with DFT. There were also subtle changes to the U1, O1, and O3 atom positions. Tabulated powder diffraction data (d's and I's) for the Metastudtite have been derived from the refined model and these new values can serve to augment the PDF entry 01-081-9033 with a more updated entry based on observed X-ray powder diffraction data.

scholarly journals Crystal structure of anhydrous tripotassium citrate from laboratory X-ray powder diffraction data and DFT comparison

2016 ◽  
Vol 72 (8) ◽  
pp. 1159-1162 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Three Dimensional ◽  
Carboxylate Group ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Graph Set

The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)]n, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KOn] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to thecaxis. The only hydrogen bond is an intramolecular one involving the hydroxy group and the central carboxylate group, with graph-set motifS(5).

scholarly journals Crystal structures of two magnesium citrates from powder diffraction data

2020 ◽  
Vol 76 (10) ◽  
pp. 1611-1616
Author(s):  
James A. Kaduk
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Magnesium Citrate ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Cation Coordination ◽  
Citrate Anion

The crystal structures of magnesium hydrogen citrate dihydrate, Mg(HC6H5O7)(H2O)2, (I), and bis(dihydrogen citrato)magnesium, Mg(H2C6H5O7)2, (II), have been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. In (I), the citrate anion occurs in the trans, trans-conformation, and triply chelates to the Mg cation. In (II), the citrate anion is trans, gauche, and doubly chelates to the Mg cation. In both compounds the Mg cation coordination polyhedron is an octahedron. In (I), the MgO6 coordination polyhedra are isolated, while in (II), they share edges to form chains. Strong O—H...O hydrogen bonds are prominent in the two structures, as well as in the previously reported magnesium citrate decahydrate.

scholarly journals Crystal structure of trirubidium citrate from laboratory X-ray powder diffraction data and DFT comparison

2017 ◽  
Vol 73 (2) ◽  
pp. 250-253 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Three Dimensional ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Methylene Groups ◽  
Graph Set

The crystal structure of trirubidium citrate, 3Rb+·C6H5O73−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The two independent Rb+cations are seven- and eight-coordinate, with bond-valence sums of 0.99 and 0.92 valence units. The coordination polyhedra share edges and corners to form a three-dimensional framework. The only hydrogen bond is an intramolecular one between the hydroxy group and the central carboxylate, with graph setS(5). The hydrophobic methylene groups lie in pockets in the framework.

scholarly journals Crystal structure of trirubidium citrate monohydrate from laboratory X-ray powder diffraction data and DFT comparison

2017 ◽  
Vol 73 (2) ◽  
pp. 227-230 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Three Dimensional ◽  
Powder Diffraction Data ◽  
Hydrogen Bond Donor ◽  
X Ray ◽  
Intramolecular Hydrogen

The crystal structure of the title compound, 3Rb+·C6H5O73−·H2O, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The hydroxy group participates in an intramolecular hydrogen bond to the deprotonated central carboxylate group with graph-set motifS(5). The water molecule acts as a hydrogen-bond donor to both terminal and central carboxylate O atoms. The three independent rubidium cations are seven-, six- and six-coordinate, with bond-valence sums of 0.84, 1.02, and 0.95, respectively. In the extended structure, their polyhedra share edges and corners to form a three-dimensional network. The hydrophobic methylene groups occupy channels along thebaxis.

scholarly journals Crystal structure of dirubidium hydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison

2017 ◽  
Vol 73 (1) ◽  
pp. 92-95 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Acid Group ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Methylene Groups ◽  
A Chain

The crystal structure of dirubidium hydrogen citrate, 2Rb+·HC6H5O72−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The un-ionized carboxylic acid group forms helical chains of very strong hydrogen bonds (O...O ∼ 2.42 Å) along thebaxis. The hydroxy group participates in a chain of intra- and intermolecular hydrogen bonds along thecaxis. These hydrogen bonds result in corrugated hydrogen-bonded layers in thebcplane. The Rb+cations are six-coordinate, and share edges and corners to form layers in theabplane. The interlayer contacts are composed of the hydrophobic methylene groups.

Molecular and crystalline structures of three (S)-4-alkoxycarbonyl-2-azetidinones containing long alkyl side chains from synchrotron X-ray powder diffraction data

2009 ◽  
Vol 65 (6) ◽  
pp. 724-730 ◽  
Author(s):  
Luis E. Seijas ◽  
Asiloé J. Mora ◽  
Gerzon E. Delgado ◽  
Francisco López-Carrasquero ◽  
María E. Báez ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
Functional Theory ◽  
X Ray ◽  
Alkyl Side Chains ◽  
Derivatives Of ◽  
Average Bond

The (S)-4-alkoxo-2-azetidinecarboxylic acids are optically active β-lactam derivatives of aspartic acid, which are used as precursors of carbapenem-type antibiotics and poly-β-aspartates. The crystal structures of three (S)-4-alkoxo-2-azetidinecarboxylic acids with alkyl chains with 10, 12 and 16 C atoms were solved using parallel tempering and refined against the X-ray powder diffraction data using the Rietveld method. The azetidinone rings in the three compounds display a pattern of asymmetrical bond distances and an almost planar conformation; these characteristics are compared with periodic solid-state, gas-phase density-functional theory (DFT) calculations and MOGUL average bond distances and angles from the CSD. The compounds pack along [001] as corrugated sheets separated by approximately 4.40 Å and connected by hydrogen bonds of the type N—H...O.

Crystal structure of citalopram hydrobromide, C20H22FN2OBr

2016 ◽  
Vol 31 (3) ◽  
pp. 176-184
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
Functional Theory ◽  
X Ray ◽  
Van Der Waals Attraction

The crystal structure of citalopram hydrobromide has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Citalopram hydrobromide crystallizes in space group P21/c (#14) with a = 10.766 45(6), b = 33.070 86(16), c = 10.892 85(5) Å, β = 90.8518(3)°, V = 3878.03(4) Å3, and Z = 8. N–H⋯Br hydrogen bonds are important to the structure, but the crystal energy is dominated by van der Waals attraction. The powder pattern was submitted to International Centre for Diffraction Data for inclusion in the Powder Diffraction File™.

Crystal structure of tezacaftor Form A, C26H27F3N2O6

2021 ◽  
Vol 36 (1) ◽  
pp. 56-62
Author(s):  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
X Ray

The crystal structure of tezacaftor Form A has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Tezacaftor Form A crystallizes in space group C2 (#5) with a = 21.05142(6), b = 6.60851(2), c = 17.76032(5) Å, β = 95.8255(2)°, V = 2458.027(7) Å3, and Z = 4. The crystal structure is dominated by van der Waals interactions. O–H⋯O hydrogen bonds link the molecules in chains along the b-axis, and there are a variety of C–H⋯O hydrogen bonds, both intra- and intermolecular. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).

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