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Acta Crystallographica. Section C,... Feb 2022In a detailed powder diffraction study of the structural forms of psilocybin, Sherwood [ C, 36–55] cast doubt that any other anhydrous polymorphs could exist.
In a detailed powder diffraction study of the structural forms of psilocybin, Sherwood [ C, 36–55] cast doubt that any other anhydrous polymorphs could exist.
Topics: Crystallography, X-Ray; Hallucinations; Humans; Hydrogen Bonding
PubMed: 35119383
DOI: 10.1107/S2053229622000511 -
Molecules (Basel, Switzerland) Aug 2021The solvatomorphism of the anthelmintic drug moxidectin is investigated, and a new solvatomorph with nitromethane is reported. Moreover, the hitherto unknown crystal...
The solvatomorphism of the anthelmintic drug moxidectin is investigated, and a new solvatomorph with nitromethane is reported. Moreover, the hitherto unknown crystal structures of the solvatomorphs with ethanol and 2-propanol are reported and discussed. The thermal characterization of these solvatomorphs through variable-temperature powder X-ray diffraction analysis (VT-PXRD) is also described, providing new insights into the crystallochemistry of this active pharmaceutical ingredient.
Topics: Crystallography, X-Ray; Hydrogen Bonding; Macrolides; Molecular Conformation; Powder Diffraction; Solvents; Temperature
PubMed: 34443452
DOI: 10.3390/molecules26164869 -
Acta Crystallographica. Section C,... Aug 2019
PubMed: 31380782
DOI: 10.1107/S2053229619010520 -
Journal of Applied Crystallography Jun 2023The high-intensity time-of-flight (TOF) neutron diffractometer POWTEX for powder and texture analysis is currently being built prior to operation in the eastern guide...
The high-intensity time-of-flight (TOF) neutron diffractometer POWTEX for powder and texture analysis is currently being built prior to operation in the eastern guide hall of the research reactor FRM II at Garching close to Munich, Germany. Because of the world-wide He crisis in 2009, the authors promptly initiated the development of He-free detector alternatives that are tailor-made for the requirements of large-area diffractometers. Herein is reported the 2017 enterprise to operate one mounting unit of the final POWTEX detector on the neutron powder diffractometer POWGEN at the Spallation Neutron Source located at Oak Ridge National Laboratory, USA. As a result, presented here are the first angular- and wavelength-dependent data from the POWTEX detector, unfortunately damaged by a 50 shock but still operating, as well as the efforts made both to characterize the transport damage and to successfully recalibrate the voxel positions in order to yield nonetheless reliable measurements. Also described is the current data reduction process using the algorithm implemented in [Arnold (2014). , , 156-166]. The final part of the data treatment chain, namely a novel multi-dimensional refinement using a modified version of the software suite [Toby & Von Dreele (2013). , 544-549], is compared with a standard data treatment of the same event data conventionally reduced as TOF diffraction patterns and refined with the unmodified version of . This involves both determining the instrumental resolution parameters using POWGEN's powdered diamond standard sample and the refinement of a friendly-user sample, BaZn(NCN). Although each structural parameter on its own looks similar upon comparing the conventional (1D) and multi-dimensional (2D) treatments, also in terms of precision, a closer view shows small but possibly significant differences. For example, the somewhat suspicious proximity of the and lattice parameters of BaZn(NCN) crystallizing in as resulting from the 1D refinement (0.008 Å) is five times less pronounced in the 2D refinement (0.038 Å). Similar features are found when comparing bond lengths and bond angles, the two N-C-N units are less differently bent in the 1D results (173 and 175°) than in the 2D results (167 and 173°). The results are of importance not only for POWTEX but also for other neutron TOF diffractometers with large-area detectors, like POWGEN at the SNS or the future DREAM beamline at the European Spallation Source.
PubMed: 37284252
DOI: 10.1107/S1600576723002819 -
Acta Crystallographica. Section E,... Jun 2016The crystal structure of anhydrous tris-odium citrate, Na3(C6H5O7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using...
The crystal structure of anhydrous tris-odium citrate, Na3(C6H5O7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory (DFT). There are two independent five-coordinate Na(+) and one six-coordinate Na(+) cations in the asymmetric unit. The [NaO5] and [NaO6] polyhedra share edges and corners to form a three-dimensional framework. There are channels parallel to the a and b axes in which the remainder of the citrate anions reside. The only hydrogen bonds are an intra-molecular one between the hy-droxy group and one of the terminal carboxyl-ate O atoms and an intermolecular one between a methylene group and the hydroxyl O atom.
PubMed: 27308044
DOI: 10.1107/S2056989016007453 -
IUCrData May 2020The crystal structure of di-ammonium potassium citrate, 2NH ·K·CHO , has been solved and refined using laboratory X-ray powder diffraction data and optimized using...
The crystal structure of di-ammonium potassium citrate, 2NH ·K·CHO , has been solved and refined using laboratory X-ray powder diffraction data and optimized using density functional theory. The KO coordination polyhedra are isolated. The ammonium cations and the hydro-phobic methyl-ene sides of the citrate anions occupy the spaces between the coordination polyhedra. Each hydrogen atom of the ammonium ions acts as a donor in a charge-assisted N-H⋯O, N-H⋯(O,O) or N-H⋯(O,O,O) hydrogen bond. There is an intra-molecular O-H⋯O hydrogen bond in the citrate anion between the hydroxide group and one of the terminal carboxyl-ate groups.
PubMed: 36337153
DOI: 10.1107/S2414314620006124 -
Journal of Applied Crystallography Aug 2021X-ray diffractometers primarily designed for surface X-ray diffraction are often used to measure the diffraction from powders, textured materials and fiber-texture...
X-ray diffractometers primarily designed for surface X-ray diffraction are often used to measure the diffraction from powders, textured materials and fiber-texture samples in 2θ scans. Unlike in high-energy powder diffraction, only a fraction of the powder rings is typically measured, and the data consist of many detector images across the 2θ range. Such diffractometers typically scan in directions not possible on a conventional laboratory diffractometer, which gives enhanced control of the scattering vector relative to the sample orientation. There are, however, very few examples where the measured intensity is directly used, such as for profile/Rietveld refinement, as is common with other powder diffraction data. Although the underlying physics is known, converting the data is time consuming and the appropriate corrections are dispersed across several publications, often not with powder diffraction in mind. This paper presents the angle calculations and correction factors required to calculate meaningful intensities for 2θ scans with a (2 + 3)-type diffractometer and an area detector. Some of the limitations with respect to texture, refraction and instrumental resolution are also discussed, as is the kind of information that one can hope to obtain.
PubMed: 34429722
DOI: 10.1107/S1600576721006245 -
Molecules (Basel, Switzerland) Nov 2021Warfarin sodium is a low-dose pharmaceutical blood thinner that exists in two forms: the clathrate form and the amorphous form. In commercially available warfarin sodium...
Warfarin sodium is a low-dose pharmaceutical blood thinner that exists in two forms: the clathrate form and the amorphous form. In commercially available warfarin sodium oral suspension, the active pharmaceutical ingredient (API) is added in the amorphous state. This study investigates the apparent instability of the commercially available warfarin liquid oral formulation using Raman and IR spectroscopy, X-ray diffraction, differential scanning calorimetry, UV spectroscopy, and optical microscopy. Warfarin, not its sodium salt, was identified as the undissolved solid existing in the suspension. This was found to be due to the dissociation of sodium salt and the protonation of the warfarin ion in the liquid phase, which triggered the crystallization of the sparingly soluble unsalted form. The coexistence of protonated and unprotonated warfarin ions in the supernatant, as detected by Raman and UV spectroscopy, confirmed this assumption. Study of the dissolution of warfarin sodium amorphous salt and crystalline sodium clathrate in the placebo and pure water verified the results. The effect of pH and temperature on warfarin precipitation was also explored.
Topics: Administration, Oral; Drug Compounding; Drug Stability; Molecular Structure; Particle Size; Warfarin
PubMed: 34771040
DOI: 10.3390/molecules26216631 -
IUCrJ Nov 2014Metal-organic frameworks (MOFs) are one of the most intensely studied material types in recent times. Their networks, resulting from the formation of strong bonds... (Review)
Review
Metal-organic frameworks (MOFs) are one of the most intensely studied material types in recent times. Their networks, resulting from the formation of strong bonds between inorganic and organic building units, offer unparalled chemical diversity and pore environments of growing complexity. Therefore, advances in single-crystal X-ray diffraction equipment and techniques are required to characterize materials with increasingly larger surface areas, and more complex linkers. In addition, whilst structure solution from powder diffraction data is possible, the area is much less populated and we detail the current efforts going on here. We also review the growing number of reports on diffraction under non-ambient conditions, including the response of MOF structures to very high pressures. Such experiments are important due to the expected presence of stresses in proposed applications of MOFs - evidence suggesting rich and complex behaviour. Given the entwined and inseparable nature of their structure, properties and applications, it is essential that the field of structural elucidation is able to continue growing and advancing, so as not to provide a rate-limiting step on characterization of their properties and incorporation into devices and applications. This review has been prepared with this in mind.
PubMed: 25485136
DOI: 10.1107/S2052252514020351 -
Acta Crystallographica Section B,... Apr 2021Dehydrocoupling of the adduct of dimethylamine and borane, NH(CH)-BH leads to dimethylaminoborane with formal composition N(CH)-BH. The structure of this product depends...
Dehydrocoupling of the adduct of dimethylamine and borane, NH(CH)-BH leads to dimethylaminoborane with formal composition N(CH)-BH. The structure of this product depends on the conditions of the synthesis; it may crystallize either as a dimer in a triclinic space group forming a four-membered ring [N(CH)-BH] or as a trimer forming a six-membered ring [N(CH)-BH] in an orthorhombic space group. Due to the denser packing, the six-membered ring in the trimer structure should be energetically more stable than the four-membered ring. The triclinic structure is stable at low temperatures. Heating the triclinic phase above 290 K leads to a second-order phase transition to a new monoclinic polymorph. While the crystal structures of the triclinic and orthorhombic phases were already known in the literature, the monoclinic crystal structure was determined from powder diffraction data in this study. Monoclinic dimethylaminoborane crystallizes in space group C2/m with the boron and nitrogen atoms located on the mirror plane, Wyckoff position 4i, while the carbon and hydrogen atoms are on the general position 8j.
PubMed: 33843738
DOI: 10.1107/S2052520621001979