scholarly journals Furosemide's one little hydrogen atom: NMR crystallography structure verification of powdered molecular organics

2016 ◽  
Vol 52 (40) ◽  
pp. 6685-6688 ◽  
Author(s):  
Cory M. Widdifield ◽  
Harry Robson ◽  
Paul Hodgkinson
Keyword(s):  
Hydrogen Atom ◽  
Crystal Structures ◽  
Molecular Crystal ◽  
Structural Databases ◽  
Nmr Crystallography

The potential of NMR crystallography to verify molecular crystal structures deposited in structural databases is evaluated, with two structures of the pharmaceutical furosemide serving as examples.

Advancing the use of Voronoi–Dirichlet polyhedra to describe interactions in organic molecular crystal structures by the example of galunisertib polymorphs

CrystEngComm ◽  
2021 ◽  
Author(s):  
Viktor N. Serezhkin ◽  
Anton V. Savchenkov
Keyword(s):  
Crystal Structures ◽  
Molecular Crystal ◽  
Noncovalent Interactions ◽  
Organic Molecular Crystal ◽  
Universal Approach ◽  
Structure Properties

The universal approach for studying structure/properties relationships shows that every polymorph of galunisertib is characterized with unique noncovalent interactions.

scholarly journals Crystal-to-Crystal Transformation from K2[Co(C2O4)2(H2O)2]·4H2O to K2[Co(μ-C2O4)(C2O4)]

2021 ◽  
Vol 7 (6) ◽  
pp. 77
Author(s):  
Bin Zhang ◽  
Yan Zhang ◽  
Guangcai Chang ◽  
Zheming Wang ◽  
Daoben Zhu
Keyword(s):  
Hydrogen Bond ◽  
Physical Properties ◽  
Crystal Structures ◽  
Molecular Crystal ◽  
Trigonal Prism ◽  
Space Group ◽  
Cell Parameters ◽  
Oxalate Anion ◽  
Crystal Transformation ◽  
Antiferromagnetic Ordering

Crystal-to-crystal transformation is a path to obtain crystals with different crystal structures and physical properties. K2[Co(C2O4)2(H2O)2]·4H2O (1) is obtained from K2C2O4·2H2O, CoCl2·6H2O in H2O with a yield of 60%. It is crystallized in the triclinic with space group P1 and cell parameters: a = 7.684(1) Å, b = 9.011(1) Å, c = 10.874(1) Å, α = 72.151(2)°, β = 70.278(2)°, γ = 80.430(2)°, V = 670.0(1) Å3, Z = 2 at 100 K. 1 is composed of K+, mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. Co2+ is coordinated by two bidentated oxalate anion and two H2O in an octahedron environment. There is a hydrogen bond between mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. K2[Co(μ-C2O4)(C2O4)] (2) is obtained from 1 by dehydration. The cell parameters of 2 are a = 8.460(5) Å, b = 6.906 (4) Å, c = 14.657(8) Å, β = 93.11(1)°, V = 855.0(8) Å3 at 100 K, with space group in P2/c. It is composed of K+ and zigzag [Co(μ-C2O4)(C2O42−]n chain. Co2+ is coordinated by two bisbendentate oxalate and one bidentated oxalate anion in trigonal-prism. 1 is an antiferromagnetic molecular crystal. The antiferromagnetic ordering at 8.2 K is observed in 2.

scholarly journals Validation of molecular crystal structures from powder diffraction data with dispersion-corrected density functional theory (DFT-D)

2014 ◽  
Vol 70 (6) ◽  
pp. 1020-1032 ◽  
Author(s):  
Jacco van de Streek ◽  
Marcus A. Neumann
Keyword(s):  
Density Functional Theory ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Energy Minimization ◽  
Molecular Crystal ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
High Quality ◽  
Functional Theory ◽  
Atomic Coordinates

In 2010 we energy-minimized 225 high-quality single-crystal (SX) structures with dispersion-corrected density functional theory (DFT-D) to establish a quantitative benchmark. For the current paper, 215 organic crystal structures determined from X-ray powder diffraction (XRPD) data and published in an IUCr journal were energy-minimized with DFT-D and compared to the SX benchmark. The on average slightly less accurate atomic coordinates of XRPD structures do lead to systematically higher root mean square Cartesian displacement (RMSCD) values upon energy minimization than for SX structures, but the RMSCD value is still a good indicator for the detection of structures that deserve a closer look. The upper RMSCD limit for a correct structure must be increased from 0.25 Å for SX structures to 0.35 Å for XRPD structures; the grey area must be extended from 0.30 to 0.40 Å. Based on the energy minimizations, three structures are re-refined to give more precise atomic coordinates. For six structures our calculations provide the missing positions for the H atoms, for five structures they provide corrected positions for some H atoms. Seven crystal structures showed a minor error for a non-H atom. For five structures the energy minimizations suggest a higher space-group symmetry. For the 225 SX structures, the only deviations observed upon energy minimization were three minor H-atom related issues. Preferred orientation is the most important cause of problems. A preferred-orientation correction is the only correction where the experimental data are modified to fit the model. We conclude that molecular crystal structures determined from powder diffraction data that are published in IUCr journals are of high quality, with less than 4% containing an error in a non-H atom.

scholarly journals Investigation of structure and dynamics in a photochromic molecular crystal by NMR crystallography

2018 ◽  
Vol 57 (5) ◽  
pp. 230-242
Author(s):  
Benjamin L. Dale ◽  
Nathan R. Halcovitch ◽  
Michael J.G. Peach ◽  
John M. Griffin
Keyword(s):  
Molecular Crystal ◽  
Structure And Dynamics ◽  
Nmr Crystallography

Ab initio crystal structure prediction of magnesium (poly)sulfides and calculation of their NMR parameters

2017 ◽  
Vol 73 (3) ◽  
pp. 229-233 ◽  
Author(s):  
Gregor Mali
Keyword(s):  
Ab Initio ◽  
Crystal Structures ◽  
Structure Prediction ◽  
Density Functional ◽  
Coupling Constants ◽  
Theory Approach ◽  
Nmr Parameters ◽  
Rocksalt Structure ◽  
Quadrupolar Coupling ◽  
Nmr Crystallography

Ab initio prediction of sensible crystal structures can be regarded as a crucial task in the quickly-developing methodology of NMR crystallography. In this contribution, an evolutionary algorithm was used for the prediction of magnesium (poly)sulfide crystal structures with various compositions. The employed approach successfully identified all three experimentally detected forms of MgS, i.e. the stable rocksalt form and the metastable wurtzite and zincblende forms. Among magnesium polysulfides with a higher content of sulfur, the most probable structure with the lowest formation energy was found to be MgS2, exhibiting a modified rocksalt structure, in which S2− anions were replaced by S2 2− dianions. Magnesium polysulfides with even larger fractions of sulfur were not predicted to be stable. For the lowest-energy structures, 25Mg quadrupolar coupling constants and chemical shift parameters were calculated using the density functional theory approach. The calculated NMR parameters could be well rationalized by the symmetries of the local magnesium environments, by the coordination of magnesium cations and by the nature of the surrounding anions. In the future, these parameters could serve as a reference for the experimentally determined 25Mg NMR parameters of magnesium sulfide species.

scholarly journals Crystal structures of two furazidin polymorphs revealed by a joint effort of crystal structure prediction and NMR crystallography

2020 ◽  
Vol 76 (3) ◽  
pp. 322-335 ◽  
Author(s):  
Marta K. Dudek ◽  
Piotr Paluch ◽  
Edyta Pindelska
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Structure Prediction ◽  
Structural Features ◽  
Crystal Structure Determination ◽  
Crystal Structure Prediction ◽  
Crystal Forms ◽  
Space Groups ◽  
Nmr Crystallography

This work presents the crystal structure determination of two elusive polymorphs of furazidin, an antibacterial agent, employing a combination of crystal structure prediction (CSP) calculations and an NMR crystallography approach. Two previously uncharacterized neat crystal forms, one of which has two symmetry-independent molecules (form I), whereas the other one is a Z′ = 1 polymorph (form II), crystallize in P21/c and P 1 space groups, respectively, and both are built by different conformers, displaying different intermolecular interactions. It is demonstrated that the usage of either CSP or NMR crystallography alone is insufficient to successfully elucidate the above-mentioned crystal structures, especially in the case of the Z′ = 2 polymorph. In addition, cases of serendipitous agreement in terms of 1H or 13C NMR data obtained for the CSP-generated crystal structures different from the ones observed in the laboratory (false-positive matches) are analyzed and described. While for the majority of analyzed crystal structures the obtained agreement with the NMR experiment is indicative of some structural features in common with the experimental structure, the mentioned serendipity observed in exceptional cases points to the necessity of caution when using an NMR crystallography approach in crystal structure determination.

scholarly journals Stable rotation of fullerenes in molecular crystal structures

2020 ◽  
Vol 1537 ◽  
pp. 012006
Author(s):  
A M Bubenchikov ◽  
M A Bubenchikov ◽  
D V Mamontov
Keyword(s):  
Crystal Structures ◽  
Molecular Crystal ◽  
Stable Rotation

Crystal-Structures of 2 3-Substituted 10,11-Dimethoxy-1,2,3,4,5,6-Hexahydro-7,9-etheno-3-benzazecine Derivatives

1989 ◽  
Vol 42 (2) ◽  
pp. 321
Author(s):  
XY Jia ◽  
JB Bremner ◽  
BW Skelton ◽  
AH White ◽  
KN Winzenberg
Keyword(s):  
Hydrogen Atom ◽  
Chemical Shift ◽  
Single Crystal ◽  
Crystal Structures ◽  
Naphthalene Ring ◽  
Methyl Derivative ◽  
X Ray ◽  
Structure Determinations

The title compounds are 3-aza[6](1,7)-naphthalenophanes with 3-Me and 3-CO2Me substituents, C18H23NO2 and C19H23NO4; in the former the chemical shift of the naphthalene hydrogen enclosed by the medium nitrogen-containing ring is the highest yet observed in a derivative of this type ( σ 9.33). In order to examine the environment of this hydrogen atom and the expected associated naphthalene ring distortions in both compounds, single-crystal X-ray structure determinations have been carried out at 295 K showing the transannular H…N distance in the methyl derivative to be remarkably short at 2.08(2) � . Crystals are triclinic, P1, a 11.683(3), b 10.846(3), c 6.729(2) �, α 90.08(2), β 93.33(2), γ 112.88 Z 2; R was 0.041 for 1378 'observed' reflections. Crystals of the 3-CO2Me derivative are also triclinic, P1, a 12.587(9), b 10.650(4), c 6.758(3) � , a 91.91(3), β 100.51(4), γ 104.74(5)° Z 2; R 0.067 for 1267 'observed' reflections.

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