scholarly journals A second polymorph of sodium dihydrogen citrate, NaH2C6H5O7: structure solution from powder diffraction data and DFT comparison

2016 ◽  
Vol 72 (6) ◽  
pp. 854-857 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Commercial Sample ◽  
Acta Cryst ◽  
Coordination Polyhedra ◽  
Structure Solution ◽  
Sodium Dihydrogen

The crystal structure of a second polymorph of sodium dihydrogen citrate, Na+·H2C6H5O7−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The powder pattern of the commercial sample used in this study did not match that corresponding to the known crystal structure [Gluskeret al.(1965).Acta Cryst.19, 561–572; refcode NAHCIT]. In this polymorph, the [NaO7] coordination polyhedra form edge-sharing chains propagating along theaaxis, while in NAHCIT the octahedral [NaO6] groups form edge-sharing pairs bridged by two hydroxy groups. The most notable difference is that in this polymorph one of the terminal carboxyl groups is deprotonated, while in NAHCIT the central carboxylate group is deprotonated, as is more typical.

scholarly journals Crystal structure of dilithium potassium citrate, Li2KC6H5O7 determined from powder diffraction data and DFT calculations

2019 ◽  
Vol 75 (3) ◽  
pp. 410-413 ◽  
Author(s):  
Andrew J. Cigler ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Potassium Citrate ◽  
Hydroxyl Group ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
Li Ion ◽  
Citrate Anion

The crystal structure of poly[μ-citrato-dilithium(I)potassium(I)], [Li2K(C6H5O7)] n , has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The citrate anion triply chelates to the K+ cation through the hydroxyl group, the central carboxylate, and the terminal carboxylate. The KO7 coordination polyhedra share edges, forming chains parallel to the a axis. These chains share edges with one tetrahedral Li ion, and are bridged by edge-sharing pairs of the second tetrahedral Li ion, forming layers parallel to the ac plane.

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 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 caesium dihydrogen citrate from laboratory X-ray powder diffraction data and DFT comparison

2017 ◽  
Vol 73 (2) ◽  
pp. 133-136 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Helical Chain ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Different Types

The crystal structure of caesium dihydrogen citrate, Cs+·H2C6H5O7−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The coordination polyhedra of the nine-coordinate Cs+cations share edges to form chains along thea-axis. These chains are linked by corners along thec-axis. The un-ionized carboxylic acid groups form two different types of hydrogen bonds; one forms a helical chain along thec-axis, and the other is discrete. The hydroxy group participates in both intra- and intermolecular hydrogen bonds.

Reinterpretation of the monohydrate of clarithromycin from X-ray powder diffraction data as a trihydrate

2012 ◽  
Vol 68 (9) ◽  
pp. o369-o372 ◽  
Author(s):  
Jacco van de Streek
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Original Data ◽  
Water Molecules ◽  
Powder Diffraction Data ◽  
Acta Cryst ◽  
X Ray

Noguchi, Fujiki, Iwao, Miura & Itai [Acta Cryst.(2012), E68, o667–o668] recently reported the crystal structure of clarithromycin monohydrate from synchrotron X-ray powder diffraction data. Voids in the crystal structure suggested the possible presence of two more water molecules. After successful location of the two additional water molecules, the Rietveld refinement still showed minor problems. These were resolved by noticing that one of the chiral centres in the molecule had been inverted. The corrected crystal structure of clarithromycin trihydrate, refined against the original data, is now reported. Dispersion-corrected density functional theory calculations were used to check the final crystal structure and to position the H atoms.

scholarly journals Crystal structure solution of an elusive polymorph of Dibenzylsquaramide

2013 ◽  
Vol 28 (S2) ◽  
pp. S470-S480 ◽  
Author(s):  
Anna Portell ◽  
Xavier Alcobé ◽  
Latévi M. Lawson Daku ◽  
Radovan Černý ◽  
Rafel Prohens
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Features ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
X Ray ◽  
The Third ◽  
Group Assignment ◽  
Structure Solution

The crystal structure of the third polymorph of dibenzylsquaramide (Portell, A. et al., 2009), (fig. 1) has been determined from laboratory X-ray powder diffraction data by means of direct space methods using the computing program FOX. (Favre-Nicolin and Černý, 2002) The structure resolution has not been straightforward due to several difficulties on the indexing process and in the space group assignment. The asymmetric unit contains two different conformers, which has implied an additional difficulty during the Rietveld (Rietveld, 1969) refinement. All these issues together with particular structural features of disquaramides are discussed.

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.

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