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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 -
IUCrData Jan 2023The structure of the title compound, CHNO, reported by Smalley [(2021). , 524-534] from powder diffraction data and N NMR spectroscopy, is confirmed using...
The structure of the title compound, CHNO, reported by Smalley [(2021). , 524-534] from powder diffraction data and N NMR spectroscopy, is confirmed using low-temperature data from a twinned crystal. The tautomer in the solid state is alloxazine (1-benzo[]pteridine-2,4-dione) rather than isoalloxazine (10-benzo[]pteridine-2,4-dione). In the extended structure, the mol-ecules form hydrogen-bonded chains propagating in the [01] direction through alternating centrosymmetric (8) rings with pairwise N-H⋯O inter-actions and centrosymmetric (8) rings with pairwise N-H⋯N inter-actions. The crystal chosen for data collection was found to be a non-merohedral twin (180° rotation about [001]) in a 0.446 (4):0.554 (6) domain ratio.
PubMed: 36794048
DOI: 10.1107/S2414314622012238 -
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 -
Scientific Reports Jan 2023Illustrated papyruses from Ancient Egypt have survived across millennia, depicting with vivid colors numerous stories and practices from a distant past. We have...
Illustrated papyruses from Ancient Egypt have survived across millennia, depicting with vivid colors numerous stories and practices from a distant past. We have investigated a series of illustrated papyruses from Champollion's private collection showing scenes from the Book of the Dead, a document essential to prepare for the afterlife. The nature of the different pigments and their distribution are revealed by combining optical microscopy, Raman spectroscopy, and synchrotron X-ray powder diffraction and fluorescence. The standardized three-step process from the New Kingdom period was used, comprising a preparatory drawing made of red hematite, a coloring step using pigments from the Egyptian palette, and a final black contour drawn with a carbon-based ink. Interestingly, specific pigment mixes were deliberately chosen to obtain different shades. In some parts, the final contour significantly differs from the preliminary drawing, revealing the artist's creativity. These results enhance our knowledge of illustrative practices in Ancient Egypt.
Topics: History, Ancient; Egypt, Ancient; Spectrum Analysis, Raman; Microscopy; Egypt
PubMed: 36627360
DOI: 10.1038/s41598-023-27761-7 -
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 -
IUCrJ Jan 2020Single crystals of the high-pressure phases II and III of pyridine have been obtained by crystallization at 1.09 and 1.69 GPa, revealing the crystal structure of...
Single crystals of the high-pressure phases II and III of pyridine have been obtained by crystallization at 1.09 and 1.69 GPa, revealing the crystal structure of phase III for the first time using X-ray diffraction. Phase II crystallizes in 222 with ' = 1 and phase III in 422 with ' = ½. Neutron powder diffraction experiments using pyridine-d establish approximate equations of state of both phases. The space group and unit-cell dimensions of phase III are similar to the structures of other simple compounds with molecular symmetry, and the phase becomes stable at high pressure because it is topologically close-packed, resulting in a lower molar volume than the topologically body-centred cubic phase II. Phases II and III have been observed previously by Raman spectroscopy, but have been mis-identified or inconsistently named. Raman spectra collected on the same samples as used in the X-ray experiments establish the vibrational characteristics of both phases unambiguously. The pyridine molecules interact in both phases through CH⋯π and CH⋯N interactions. The nature of individual contacts is preserved through the phase transition between phases III and II, which occurs on decompression. A combination of rigid-body symmetry mode analysis and density functional theory calculations enables the soft vibrational lattice mode which governs the transformation to be identified.
PubMed: 31949905
DOI: 10.1107/S2052252519015616 -
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