Open-access and free articles in Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
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Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.en-gbCopyright (c) 2024 International Union of CrystallographyInternational Union of CrystallographyInternational Union of CrystallographytextActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.text/htmlhttps://journals.iucr.orgOpen-access and free articles in Acta Crystallographica Section B Structural Science, Crystal Engineering and Materialsurn:issn:2052-5192yearly2002-02-01T00:00+00:006Acta Crystallographica Section B Structural Science, Crystal Engineering and Materialsurn:issn:2052-5192Copyright (c) 2024 International Union of Crystallographymed@iucr.orgOpen-access and free articles in Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialshttp://journals.iucr.org/logos/rss10b.gif
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Still imageLattice response to the radiation damage of molecular crystals: radiation-induced versus thermal expansivity
http://scripts.iucr.org/cgi-bin/paper?ra5138
The interaction of intense synchrotron radiation with molecular crystals frequently modifies the crystal structure by breaking bonds, producing fragments and, hence, inducing disorder. Here, a second-rank tensor of radiation-induced lattice strain is proposed to characterize the structural susceptibility to radiation. Quantitative estimates are derived using a linear response approximation from experimental data collected on three materials Hg(NO3)2(PPh3)2, Hg(CN)2(PPh3)2 and BiPh3 [PPh3 = triphenylphosphine, P(C6H5)3; Ph = phenyl, C6H5], and are compared with the corresponding thermal expansivities. The associated eigenvalues and eigenvectors show that the two tensors are not the same and therefore probe truly different structural responses. The tensor of radiative expansion serves as a measure of the susceptibility of crystal structures to radiation damage.The interaction of intense synchrotron radiation with molecular crystals frequently modifies the crystal structure by inducing disorder. A second-rank tensor of radiation-induced lattice strain is proposed to characterize lattice susceptibility to the radiation.texthttps://creativecommons.org/licenses/by/4.0/The interaction of intense synchrotron radiation with molecular crystals frequently modifies the crystal structure by breaking bonds, producing fragments and, hence, inducing disorder. Here, a second-rank tensor of radiation-induced lattice strain is proposed to characterize the structural susceptibility to radiation. Quantitative estimates are derived using a linear response approximation from experimental data collected on three materials Hg(NO3)2(PPh3)2, Hg(CN)2(PPh3)2 and BiPh3 [PPh3 = triphenylphosphine, P(C6H5)3; Ph = phenyl, C6H5], and are compared with the corresponding thermal expansivities. The associated eigenvalues and eigenvectors show that the two tensors are not the same and therefore probe truly different structural responses. The tensor of radiative expansion serves as a measure of the susceptibility of crystal structures to radiation damage.RADIATION DAMAGE; THERMAL EXPANSION; MOLECULAR CRYSTALS; DISORDERtext/htmlenMcMonagle, C.J.Fuller, C.A.Hupf, E.Malaspina, L.A.Grabowsky, S.Chernyshov, D.urn:issn:2052-5206Lattice response to the radiation damage of molecular crystals: radiation-induced versus thermal expansivitydoi:10.1107/S20525206230106362024-01-04International Union of Crystallography1318018February 2024research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials2052-52062052-5206https://creativecommons.org/licenses/by/4.0/med@iucr.org2024-01-04High-throughput nanoscale crystallization of dihydropyridine active pharmaceutical ingredients
http://scripts.iucr.org/cgi-bin/paper?rm5073
Single-crystal X-ray diffraction analysis of small molecule active pharmaceutical ingredients is a key technique in the confirmation of molecular connectivity, including absolute stereochemistry, as well as the solid-state form. However, accessing single crystals suitable for X-ray diffraction analysis of an active pharmaceutical ingredient can be experimentally laborious, especially considering the potential for multiple solid-state forms (solvates, hydrates and polymorphs). In recent years, methods for the exploration of experimental crystallization space of small molecules have undergone a `step-change', resulting in new high-throughput techniques becoming available. Here, the application of high-throughput encapsulated nanodroplet crystallization to a series of six dihydropyridines, calcium channel blockers used in the treatment of hypertension related diseases, is described. This approach allowed 288 individual crystallization experiments to be performed in parallel on each molecule, resulting in rapid access to crystals and subsequent crystal structures for all six dihydropyridines, as well as revealing a new solvate polymorph of nifedipine (1,4-dioxane solvate) and the first known solvate of nimodipine (DMSO solvate). This work further demonstrates the power of modern high-throughput crystallization methods in the exploration of the solid-state landscape of active pharmaceutical ingredients to facilitate crystal form discovery and structural analysis by single-crystal X-ray diffraction.The use of encapsulated nanodroplet crystallization, for high-throughput screening of a selection of dihydropyridine active pharmaceutical ingredients, resulted in access to single component crystalline forms for all examples as well as the discovery of two novel solvates.texthttps://creativecommons.org/licenses/by/4.0/Single-crystal X-ray diffraction analysis of small molecule active pharmaceutical ingredients is a key technique in the confirmation of molecular connectivity, including absolute stereochemistry, as well as the solid-state form. However, accessing single crystals suitable for X-ray diffraction analysis of an active pharmaceutical ingredient can be experimentally laborious, especially considering the potential for multiple solid-state forms (solvates, hydrates and polymorphs). In recent years, methods for the exploration of experimental crystallization space of small molecules have undergone a `step-change', resulting in new high-throughput techniques becoming available. Here, the application of high-throughput encapsulated nanodroplet crystallization to a series of six dihydropyridines, calcium channel blockers used in the treatment of hypertension related diseases, is described. This approach allowed 288 individual crystallization experiments to be performed in parallel on each molecule, resulting in rapid access to crystals and subsequent crystal structures for all six dihydropyridines, as well as revealing a new solvate polymorph of nifedipine (1,4-dioxane solvate) and the first known solvate of nimodipine (DMSO solvate). This work further demonstrates the power of modern high-throughput crystallization methods in the exploration of the solid-state landscape of active pharmaceutical ingredients to facilitate crystal form discovery and structural analysis by single-crystal X-ray diffraction.DIHYDROPYRIDINES; HIGH-THROUGHPUT CRYSTALLIZATION; SINGLE-CRYSTAL X-RAY DIFFRACTION; SMALL MOLECULE; ENCAPSULATED NANODROPLET CRYSTALLIZATIONtext/htmlenMetherall, J.P.Corner, P.A.McCabe, J.F.Hall, M.J.Probert, M.R.urn:issn:2052-5206High-throughput nanoscale crystallization of dihydropyridine active pharmaceutical ingredientsdoi:10.1107/S20525206230100532023-12-21International Union of Crystallography8014February 202412Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papers2052-52062052-52062023-12-21med@iucr.orghttps://creativecommons.org/licenses/by/4.0/Order–disorder (OD) polytypism of K3FeTe2O8(OH)2(H2O)1+x
http://scripts.iucr.org/cgi-bin/paper?yv5013
K3FeTe2O8(OH)2(H2O)2 was synthesized under hydrothermal conditions from Te(OH)6, FeSO4·7H2O and 85 wt% KOH in a 1:2:6 molar ratio. The crystal structure is built of a triperiodic network. One disordered water molecule per formula unit is located in a channel and can be partially removed by heating. Systematic one-dimensional diffuse scattering indicates a polytypic character, which is best described by application of the order–disorder theory. The major polytype is monoclinic with pseudo-orthorhombic metrics. It is interrupted by fragments of an orthorhombic polytype. The diffraction intensities are analyzed using structure factor calculations.K3FeTe2O8(OH)2(H2O)1+x crystallizes as an order–disorder structure where polytypes differ in the positions of the Fe and Te atoms. Diffuse scattering with broad peaks indicates correlated disorder.texthttps://creativecommons.org/licenses/by/4.0/K3FeTe2O8(OH)2(H2O)2 was synthesized under hydrothermal conditions from Te(OH)6, FeSO4·7H2O and 85 wt% KOH in a 1:2:6 molar ratio. The crystal structure is built of a triperiodic network. One disordered water molecule per formula unit is located in a channel and can be partially removed by heating. Systematic one-dimensional diffuse scattering indicates a polytypic character, which is best described by application of the order–disorder theory. The major polytype is monoclinic with pseudo-orthorhombic metrics. It is interrupted by fragments of an orthorhombic polytype. The diffraction intensities are analyzed using structure factor calculations.POLYTYPISM; OD THEORY; X-RAY DIFFRACTION; TELLURATEtext/htmlenWolflehner, T.Stöger, B.urn:issn:2052-5206Order–disorder (OD) polytypism of K3FeTe2O8(OH)2(H2O)1+xdoi:10.1107/S20525206230091622023-11-07International Union of Crystallography2052-52062052-52062023-11-07https://creativecommons.org/licenses/by/4.0/med@iucr.org795106December 2023518Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papersAb initio crystal structures and relative phase stabilities for the aleksite series, PbnBi4Te4Sn+2
http://scripts.iucr.org/cgi-bin/paper?dk5122
Density functional theory methods are applied to crystal structures and stabilities of phases from the aleksite homologous series, PbnBi4Te4Sn+2 (n = homologue number). The seven phases investigated correspond to n = 0 (tetradymite), 2 (aleksite-21R and -42R), 4 (saddlebackite-9H and -18H), 6 (unnamed Pb6Bi4Te4S8), 8 (unnamed Pb8Bi4Te4S10), 10 (hitachiite) and 12 (unnamed Pb12Bi4Te4S14). These seven phases correspond to nine single- or double-module structures, each comprising an odd number of atom layers, 5, 7, (5.9), 9, (7.11), 11, 13, 15 and 17, expressed by the formula: S(MpXp+1)·L(Mp+1Xp+2), where M = Pb, Bi and X = Te, S, p ≥ 2, and S and L = number of short and long modules, respectively. Relaxed structures show a and c values within 1.5% of experimental data; a and the interlayer distance dsub decrease with increasing PbS content. Variable Pb—S bond lengths contrast with constant Pb—S bond lengths in galena. All phases are n-fold superstructures of a rhombohedral subcell with c/3 = dsub*. Electron diffraction patterns show two brightest reflections at the centre of dsub*, described by the modulation vector qF = (i/N) · dsub*, i = S + L. A second modulation vector, q = γ · csub*, shows a decrease in γ, from 1.8 to 1.588, across the n = 0 to n = 12 interval. The linear relationship between γ and dsub allows the prediction of any theoretical phases beyond the studied compositional range. The upper PbS-rich limit of the series is postulated as n = 398 (Pb398Bi4Te4S400), a phase with dsub (1.726 Å) identical to that of trigonal PbS within experimental error. The aleksite series is a prime example of mixed layer compounds built with accretional homology principles.DFT is used to obtain structural information for seven members of the aleksite homologous series. Relationships between modulation vectors and the d subcell can be mathematically defined, allowing the prediction of crystal parameters for any member of the series, a valuable finding for mineral systematics and classification, and for an expanded understanding of this and other mixed-layer series.texthttps://creativecommons.org/licenses/by/4.0/Density functional theory methods are applied to crystal structures and stabilities of phases from the aleksite homologous series, PbnBi4Te4Sn+2 (n = homologue number). The seven phases investigated correspond to n = 0 (tetradymite), 2 (aleksite-21R and -42R), 4 (saddlebackite-9H and -18H), 6 (unnamed Pb6Bi4Te4S8), 8 (unnamed Pb8Bi4Te4S10), 10 (hitachiite) and 12 (unnamed Pb12Bi4Te4S14). These seven phases correspond to nine single- or double-module structures, each comprising an odd number of atom layers, 5, 7, (5.9), 9, (7.11), 11, 13, 15 and 17, expressed by the formula: S(MpXp+1)·L(Mp+1Xp+2), where M = Pb, Bi and X = Te, S, p ≥ 2, and S and L = number of short and long modules, respectively. Relaxed structures show a and c values within 1.5% of experimental data; a and the interlayer distance dsub decrease with increasing PbS content. Variable Pb—S bond lengths contrast with constant Pb—S bond lengths in galena. All phases are n-fold superstructures of a rhombohedral subcell with c/3 = dsub*. Electron diffraction patterns show two brightest reflections at the centre of dsub*, described by the modulation vector qF = (i/N) · dsub*, i = S + L. A second modulation vector, q = γ · csub*, shows a decrease in γ, from 1.8 to 1.588, across the n = 0 to n = 12 interval. The linear relationship between γ and dsub allows the prediction of any theoretical phases beyond the studied compositional range. The upper PbS-rich limit of the series is postulated as n = 398 (Pb398Bi4Te4S400), a phase with dsub (1.726 Å) identical to that of trigonal PbS within experimental error. The aleksite series is a prime example of mixed layer compounds built with accretional homology principles.ALEKSITE SERIES; MIXED LAYER COMPOUNDS; CRYSTAL STRUCTURE; DENSITY FUNCTIONAL THEORY; ELECTRON DIFFRACTIONtext/htmlenYao, J.Ciobanu, C.L.Cook, N.J.Ehrig, K.urn:issn:2052-5206Ab initio crystal structures and relative phase stabilities for the aleksite series, PbnBi4Te4Sn+2doi:10.1107/S20525206230087762023-11-01International Union of Crystallography2023-11-01https://creativecommons.org/licenses/by/4.0/med@iucr.org2052-52062052-5206Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papersDecember 2023494794826Incommensurate magnetic structure of CrAs at low temperatures and high pressures
http://scripts.iucr.org/cgi-bin/paper?xk5103
The magnetic structure of chromium arsenide CrAs is studied with neutron powder diffraction at ambient pressure in the temperature range 1.5–300 K as well as with neutron single-crystal diffraction at 2 K and 0.12 GPa. The material undergoes an anti-isostructural phase transition at TN = 267 K and atmospheric conditions, in which both orthorhombic phases have the same space-group symmetry (Pnma, Z = 4) but different distortions of the parent hexagonal structure of the NiAs type (P63/mmc, Z = 2). The magnetic structure below TN is incommensurate with the propagation vector k = (0, 0, kc). At ambient pressure, the component kc decreases from kc = 0.3807 (7) at 260 K to kc = 0.3531 (6) at 50 K. Below this temperature, it is basically constant. With increasing pressure at 2 K, kc is also constant within standard uncertainties [kc = 0.353 (2)]. For the analysis of the magnetic structure, a group-theoretical approach based on the space group of the nuclear structure and its subgroups is used. To avoid falling into false minima in the refinements, a random search for magnetic moments in the models is implemented. In the literature, the magnetic structure has been determined on the basis of powder diffraction data as a double helix propagating along the c axis. Although this double-helical model leads to satisfactory agreement factors for our powder data, it does not reproduce the intensities of the magnetic satellite reflections measured on single-crystal data in a satisfactory way and can therefore be discarded. Instead, several other models are found that lead to better agreement. Each of them is spiral-like with directional components in all three directions and with no spin-density wave character that would cause a non-constant magnetic moment. In all these models, the ordering of the spins is neither a pure helix nor a pure cycloid. Instead, the unit vectors of the spin rotation planes make an angle α, 0° < α < 90°, with respect to the c* direction. The model in superspace group P21.1′(α0γ)0s yields the best agreement factors in the refinements of the neutron single-crystal and powder diffraction data. This model is unique as it is the only one in which all the magnetic moments rotate with the same chirality.The incommensurate magnetic structure of chromium arsenide CrAs below the anti-isostructural phase transition is studied with neutron powder and single-crystal diffraction at high pressures and low temperatures.texthttps://creativecommons.org/licenses/by/4.0/The magnetic structure of chromium arsenide CrAs is studied with neutron powder diffraction at ambient pressure in the temperature range 1.5–300 K as well as with neutron single-crystal diffraction at 2 K and 0.12 GPa. The material undergoes an anti-isostructural phase transition at TN = 267 K and atmospheric conditions, in which both orthorhombic phases have the same space-group symmetry (Pnma, Z = 4) but different distortions of the parent hexagonal structure of the NiAs type (P63/mmc, Z = 2). The magnetic structure below TN is incommensurate with the propagation vector k = (0, 0, kc). At ambient pressure, the component kc decreases from kc = 0.3807 (7) at 260 K to kc = 0.3531 (6) at 50 K. Below this temperature, it is basically constant. With increasing pressure at 2 K, kc is also constant within standard uncertainties [kc = 0.353 (2)]. For the analysis of the magnetic structure, a group-theoretical approach based on the space group of the nuclear structure and its subgroups is used. To avoid falling into false minima in the refinements, a random search for magnetic moments in the models is implemented. In the literature, the magnetic structure has been determined on the basis of powder diffraction data as a double helix propagating along the c axis. Although this double-helical model leads to satisfactory agreement factors for our powder data, it does not reproduce the intensities of the magnetic satellite reflections measured on single-crystal data in a satisfactory way and can therefore be discarded. Instead, several other models are found that lead to better agreement. Each of them is spiral-like with directional components in all three directions and with no spin-density wave character that would cause a non-constant magnetic moment. In all these models, the ordering of the spins is neither a pure helix nor a pure cycloid. Instead, the unit vectors of the spin rotation planes make an angle α, 0° < α < 90°, with respect to the c* direction. The model in superspace group P21.1′(α0γ)0s yields the best agreement factors in the refinements of the neutron single-crystal and powder diffraction data. This model is unique as it is the only one in which all the magnetic moments rotate with the same chirality.INCOMMENSURATE MAGNETIC STRUCTURE; NEUTRON DIFFRACTION; EXTREME CONDITIONS; HIGH PRESSUREtext/htmlenEich, A.Grzechnik, A.Su, Y.Ouladdiaf, B.Sheptyakov, D.Wolf, T.Petricek, V.Shahed, H.Friese, K.urn:issn:2052-5206Incommensurate magnetic structure of CrAs at low temperatures and high pressuresdoi:10.1107/S205252062300817X2023-10-12International Union of Crystallography473679481December 2023research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials2052-52062052-5206med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-10-12Hydrogen bonding patterns and C—H⋯π interactions in the structure of the antiparkinsonian drug (R)-rasagiline mesylate determined using laboratory and synchrotron X-ray powder diffraction data
http://scripts.iucr.org/cgi-bin/paper?ra5135
The structure of (R)-rasagiline mesylate [(R)-RasH+·Mes−], an active pharmaceutical ingredient used to treat Parkinson's disease, is presented. The structure was determined from laboratory and synchrotron powder diffraction data, refined using the Rietveld method, and validated and optimized using dispersion-corrected DFT calculations. The unit-cell parameters obtained in both experiments are in good agreement and the refinement with both datasets converged to good agreement factors. The final parameters obtained from laboratory data were a = 5.4905 (8), b = 6.536 (2), c = 38.953 (3) Å, V = 1398.0 (4) Å3 and from synchrotron powder data were a = 5.487530 (10) Å, b = 6.528939 (12) Å, c = 38.94313 (9) Å, V = 1395.245 (5) Å3 with Z = 4 and space group P212121. Preferred orientation was properly accounted for using the synchrotron radiation data, leading to a March–Dollase parameter of 1.140 (1) instead of the 0.642 (1) value obtained from laboratory data. In the structure, (R)-RasH+ moieties form layers parallel to the ab plane connected by mesylate ions through N—H⋯O and C—H⋯O hydrogen bonds. These layers stack along the c axis and are further connected by C—H⋯π interactions. Hirshfeld surface analysis and fingerprint plot calculations indicate that the main interactions are: H⋯H (50.9%), H⋯C/C⋯H (27.1%) and H⋯O/O⋯H (21.1%).Extensive hydrogen bonding and C—H⋯π interactions dominate the packing of molecules in the antiparkinsonian drug (R)-rasagiline mesylate. The structure was determined from laboratory and synchrotron powder diffraction data and validated using DFT-D calculations.texthttps://creativecommons.org/licenses/by/4.0/The structure of (R)-rasagiline mesylate [(R)-RasH+·Mes−], an active pharmaceutical ingredient used to treat Parkinson's disease, is presented. The structure was determined from laboratory and synchrotron powder diffraction data, refined using the Rietveld method, and validated and optimized using dispersion-corrected DFT calculations. The unit-cell parameters obtained in both experiments are in good agreement and the refinement with both datasets converged to good agreement factors. The final parameters obtained from laboratory data were a = 5.4905 (8), b = 6.536 (2), c = 38.953 (3) Å, V = 1398.0 (4) Å3 and from synchrotron powder data were a = 5.487530 (10) Å, b = 6.528939 (12) Å, c = 38.94313 (9) Å, V = 1395.245 (5) Å3 with Z = 4 and space group P212121. Preferred orientation was properly accounted for using the synchrotron radiation data, leading to a March–Dollase parameter of 1.140 (1) instead of the 0.642 (1) value obtained from laboratory data. In the structure, (R)-RasH+ moieties form layers parallel to the ab plane connected by mesylate ions through N—H⋯O and C—H⋯O hydrogen bonds. These layers stack along the c axis and are further connected by C—H⋯π interactions. Hirshfeld surface analysis and fingerprint plot calculations indicate that the main interactions are: H⋯H (50.9%), H⋯C/C⋯H (27.1%) and H⋯O/O⋯H (21.1%).CRYSTAL STRUCTURE; RASAGILINE MESYLATE; STRUCTURE DETERMINATION; SYNCHROTRON RADIATION; DFT-D CALCULATIONS; HIRSHFELD SURFACE ANALYSIS; PARKINSON'S DISEASEtext/htmlenDugarte-Dugarte, A.J.Toro, R.A.van de Streek, J.Henao, J.A.Fitch, A.N.Dejoie, C.Delgado, J.M.Díaz de Delgado, G.urn:issn:2052-5206Hydrogen bonding patterns and C—H⋯π interactions in the structure of the antiparkinsonian drug (R)-rasagiline mesylate determined using laboratory and synchrotron X-ray powder diffraction datadoi:10.1107/S20525206230077582023-10-11International Union of Crystallography472December 2023462679research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materialsmed@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-10-112052-52062052-52063D electron diffraction analysis of a novel, mechanochemically synthesized supramolecular organic framework based on tetrakis-4-(4-pyridyl)phenylmethane
http://scripts.iucr.org/cgi-bin/paper?je5052
Tetrakis-4-(4-pyridyl)phenylmethane (TPPM) is a tetrahedral rigid molecule that crystallizes forming a dynamically responsive supramolecular organic framework (SOF). When exposed to different stimuli, this supramolecular network can reversibly switch from an empty to a filled solvated solid phase. This article describes a novel expanded form of a TPPM-based SOF that has been mechanochemically synthesized and whose crystal structure has been determined by 3D electron diffraction analysis using a novel electron diffractometer.A new supramolecular organic framework (SOF) based on the tetrahedral rigid molecule tetrakis-4-(4-pyridyl)phenylmethane has been mechanochemically synthesized. The crystal structure of the SOF containing benzyl alcohol has been determined using 3D electron diffraction analysis with a novel electron diffractometer.texthttps://creativecommons.org/licenses/by/4.0/Tetrakis-4-(4-pyridyl)phenylmethane (TPPM) is a tetrahedral rigid molecule that crystallizes forming a dynamically responsive supramolecular organic framework (SOF). When exposed to different stimuli, this supramolecular network can reversibly switch from an empty to a filled solvated solid phase. This article describes a novel expanded form of a TPPM-based SOF that has been mechanochemically synthesized and whose crystal structure has been determined by 3D electron diffraction analysis using a novel electron diffractometer.3D ELECTRON DIFFRACTION; ELECTRON DIFFRACTOMETER; MECHANOCHEMISTRY; SUPRAMOLECULAR ORGANIC FRAMEWORKStext/htmlenMarchetti, D.Pedrini, A.Massera, C.Faye Diouf, M.D.Jandl, C.Steinfeld, G.Gemmi, M.urn:issn:2052-52063D electron diffraction analysis of a novel, mechanochemically synthesized supramolecular organic framework based on tetrakis-4-(4-pyridyl)phenylmethanedoi:10.1107/S20525206230076802023-09-26International Union of Crystallography643279436December 2023research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials2052-52062052-5206med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-09-26Comparative study of conventional and synchrotron X-ray electron densities on molecular crystals
http://scripts.iucr.org/cgi-bin/paper?px5057
Five different electron density datasets obtained from conventional and synchrotron single crystal X-ray diffraction experiments are compared. The general aim of the study is to investigate the quality of data for electron density analysis from current state-of-the-art conventional sources, and to see how the data perform in comparison with high-quality synchrotron data. A molecular crystal of melamine was selected as the test compound due to its ability to form excellent single crystals, the light atom content, and an advantageous suitability factor of 3.6 for electron density modeling. These features make melamine an optimal system for conventional X-ray diffractometers since the inherent advantages of synchrotron sources such as short wavelength and high intensity are less critical in this case. Data were obtained at 100 K from new in-house diffractometers Rigaku Synergy-S (Mo and Ag source, HyPix100 detector) and Stoe Stadivari (Mo source, EIGER2 1M CdTe detector), and an older Oxford Diffraction Supernova (Mo source, Atlas CCD detector). The synchrotron data were obtained at 25 K from BL02B1 beamline at SPring-8 in Japan (λ = 0.2480 Å, Pilatus3 X 1M CdTe detector). The five datasets were compared on general quality parameters such as resolution, 〈I/σ〉, redundancy and R factors, as well as the more model specific fractal dimension plot and residual density maps. Comparison of the extracted electron densities reveals that all datasets can provide reliable multipole models, which overall convey similar chemical information. However, the new laboratory X-ray diffractometers with advanced pixel detector technology clearly measure data with significantly less noise and much higher reliability giving densities of higher quality, compared to the older instrument. The synchrotron data have higher resolution and lower measurement temperature, and they allow for finer details to be modeled (e.g. hydrogen κ parameters).Four electron density quality single crystal X-ray diffraction datasets on molecular crystals of melamine were obtained from both state-of-the-art laboratory instruments (Rigaku Synergy with Ag Kα and Mo Kα, Stoe Stadivari with Mo Kα) and an older X-ray diffractometer (Oxford Diffraction Supernova with Mo Kα) and the data quality and electron density models were compared with results from a high-quality synchrotron dataset (SPring-8).texthttps://creativecommons.org/licenses/by/4.0/Five different electron density datasets obtained from conventional and synchrotron single crystal X-ray diffraction experiments are compared. The general aim of the study is to investigate the quality of data for electron density analysis from current state-of-the-art conventional sources, and to see how the data perform in comparison with high-quality synchrotron data. A molecular crystal of melamine was selected as the test compound due to its ability to form excellent single crystals, the light atom content, and an advantageous suitability factor of 3.6 for electron density modeling. These features make melamine an optimal system for conventional X-ray diffractometers since the inherent advantages of synchrotron sources such as short wavelength and high intensity are less critical in this case. Data were obtained at 100 K from new in-house diffractometers Rigaku Synergy-S (Mo and Ag source, HyPix100 detector) and Stoe Stadivari (Mo source, EIGER2 1M CdTe detector), and an older Oxford Diffraction Supernova (Mo source, Atlas CCD detector). The synchrotron data were obtained at 25 K from BL02B1 beamline at SPring-8 in Japan (λ = 0.2480 Å, Pilatus3 X 1M CdTe detector). The five datasets were compared on general quality parameters such as resolution, 〈I/σ〉, redundancy and R factors, as well as the more model specific fractal dimension plot and residual density maps. Comparison of the extracted electron densities reveals that all datasets can provide reliable multipole models, which overall convey similar chemical information. However, the new laboratory X-ray diffractometers with advanced pixel detector technology clearly measure data with significantly less noise and much higher reliability giving densities of higher quality, compared to the older instrument. The synchrotron data have higher resolution and lower measurement temperature, and they allow for finer details to be modeled (e.g. hydrogen κ parameters).ELECTRON DENSITY; DATA QUALITY; MOLECULAR CRYSTAL; SINGLE CRYSTAL X-RAY DIFFRACTIONtext/htmlenVosegaard, E.S.Ahlburg, J.V.Krause, L.Iversen, B.B.urn:issn:2052-5206Comparative study of conventional and synchrotron X-ray electron densities on molecular crystalsdoi:10.1107/S20525206230066252023-09-04International Union of Crystallography2052-52062052-5206med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-09-04research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials538079391October 2023Elucidating the nature of chemical bonds in a coordination compound through quantum crystallographic techniques
http://scripts.iucr.org/cgi-bin/paper?me6237
Investigations simultaneously involving multiple techniques of quantum crystallography could be very useful to prove the consistency of obtained results or to highlight different facets of the same scientific phenomenon or problem. Pinto et al. [Acta Cryst. (2023), B79, 282–296] exploit three different quantum crystallographic techniques (Hansen & Coppens multipole model refinement, QTAIM analysis of the electron density, and Hirshfeld atom refinement) to characterize the nature of chemical bonds and of intra/intermolecular interactions in an organometallic compound.textQUANTUM CRYSTALLOGRAPHY; MULTIPOLE MODEL; HIRSHFELD ATOM REFINEMENT; TOPOLOGICAL ANALYSIS OF THE ELECTRON DENSITY; CHEMICAL BONDtext/htmlenGenoni, A.urn:issn:2052-5206Elucidating the nature of chemical bonds in a coordination compound through quantum crystallographic techniquesdoi:10.1107/S20525206230063642023-07-28International Union of Crystallographyscientific commentariesActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials425379254August 20232052-52062052-5206med@iucr.org2023-07-28Structural insight into the cooperativity of spin crossover compounds
http://scripts.iucr.org/cgi-bin/paper?ne5010
Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)2(NCS)2 (PM = N-2′-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements. The dependence of macroscopic properties on cooperativity, highlighting the role of hydrogen bonding, π–π and van der Waals interactions is discussed. Values of entropy, enthalpy and cooperativity are calculated numerically based on the Slichter–Drickamer model. The particle size dependence of the magnetic properties is probed along with the thermal exchange and the kinetic behavior of the two polymorphs based on the dependence of magnetization on temperature scan rate and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction. Also a scan-rate-dependent two-step behavior observed for the orthorhombic polymorph, which is absent for the monoclinic polymorph, is reported. Moreover, it is found that the radiation dose from synchrotron radiation affects the spin-crossover process and shifts the transition region to lower temperatures, implying that the spin crossover can be tuned with radiation damage.Macroscopic physical properties are correlated with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the spin crossover compound [Fe(PM-BiA)2(NCS)2] by employing single crystal X-ray diffraction, magnetization and DSC measurements. Focus is given on the kinetic behavior and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction.texthttps://creativecommons.org/licenses/by/4.0/Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)2(NCS)2 (PM = N-2′-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements. The dependence of macroscopic properties on cooperativity, highlighting the role of hydrogen bonding, π–π and van der Waals interactions is discussed. Values of entropy, enthalpy and cooperativity are calculated numerically based on the Slichter–Drickamer model. The particle size dependence of the magnetic properties is probed along with the thermal exchange and the kinetic behavior of the two polymorphs based on the dependence of magnetization on temperature scan rate and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction. Also a scan-rate-dependent two-step behavior observed for the orthorhombic polymorph, which is absent for the monoclinic polymorph, is reported. Moreover, it is found that the radiation dose from synchrotron radiation affects the spin-crossover process and shifts the transition region to lower temperatures, implying that the spin crossover can be tuned with radiation damage.SPIN CROSSOVER,; RADIATION DAMAGE; THERMAL CYCLIC; ENTROPY; INTERMOLECULAR INTERACTIONStext/htmlenShahed, H.Sharma, N.Angst, M.Voigt, J.Perßon, J.Prakash, P.Törnroos, K.W.Chernyshov, D.Gildenast, H.Ohl, M.Saffarini, G.Grzechnik, A.Friese, K.urn:issn:2052-5206Structural insight into the cooperativity of spin crossover compoundsdoi:10.1107/S20525206230058142023-08-11International Union of Crystallographymed@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-08-112052-52062052-5206research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials367October 2023535479The structure of magnesium stearate trihydrate determined from a micrometre-sized single crystal using a microfocused synchrotron X-ray beam
http://scripts.iucr.org/cgi-bin/paper?rm5068
Crystalline magnesium stearate has been extensively used as an additive in pharmaceutical and other industries for decades. However, the lack of suitably large crystals has hindered the determination of the crystal structure and thereby a more fundamental understanding of the structure–functionality relationship. Presented here is the structure of magnesium stearate trihydrate as determined from X-ray diffraction data of a micrometre-sized single crystal measured at a fourth-generation synchrotron facility. Despite the small size of the single crystals and the weak diffraction, it was possible to determine the positions of the non-hydrogen atoms reliably. Periodic dispersion-corrected density functional theory calculations were used to obtain the positions of the hydrogen atoms playing an important role in the overall organization of the structure via a hydrogen-bond network.The structure of the pharmaceutical lubricant magnesium stearate has been determined from micrometre-sized single crystals at a fourth-generation synchrotron.texthttps://creativecommons.org/licenses/by/4.0/Crystalline magnesium stearate has been extensively used as an additive in pharmaceutical and other industries for decades. However, the lack of suitably large crystals has hindered the determination of the crystal structure and thereby a more fundamental understanding of the structure–functionality relationship. Presented here is the structure of magnesium stearate trihydrate as determined from X-ray diffraction data of a micrometre-sized single crystal measured at a fourth-generation synchrotron facility. Despite the small size of the single crystals and the weak diffraction, it was possible to determine the positions of the non-hydrogen atoms reliably. Periodic dispersion-corrected density functional theory calculations were used to obtain the positions of the hydrogen atoms playing an important role in the overall organization of the structure via a hydrogen-bond network.MAGNESIUM STEARATE TRIHYDRATE; MOLECULAR CRYSTALS; PHARMACEUTICAL SOLIDStext/htmlenHerzberg, M.Rekis, T.Støttrup Larsen, A.Gonzalez, A.Rantanen, J.Østergaard Madsen, A.urn:issn:2052-5206The structure of magnesium stearate trihydrate determined from a micrometre-sized single crystal using a microfocused synchrotron X-ray beamdoi:10.1107/S20525206230056072023-07-08International Union of Crystallography330479335August 2023research papersMaterials and ComputationActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials2052-52062052-5206med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-07-08As predicted and more: modulated channel occupation in YZn5+x
http://scripts.iucr.org/cgi-bin/paper?dk5117
Like many complex intermetallic phases, the crystal structures of REZn5+x compounds (RE = lanthanide or Group 3 element) based on the EuMg5 type have gradually unfolded. The original reports described a complex hexagonal structure with an unusual combination of tetrahedrally close-packed regions and open spaces, as well as observations of superstructure reflections. More recently, we reinvestigated the structure of YZn5, reclassifying it as the EuMg5+x-type compound YZn5+x (x ≃ 0.2), in which disordered channels run along c through the spaces formerly considered open. In addition, DFT-chemical pressure (DFT-CP) analysis of ordered models of YZn5+x highlighted paths for communication between neighboring channels setting the stage for superstructure formation. Herein, the experimental elucidation of this effect is presented with the synthesis and structure determination of a modulated form of YZn5+x. By slow-cooling samples of YZn5+x from the annealing temperature, crystals were obtained that exhibit satellite reflections with the modulation wavevector q = {1\over 3}a* + {1\over 3}b* + 0.3041c*. Structure solution and refinement using a (3+1)D model in superspace group P31c({1\over 3}\,\!{1\over 3}σ3)00s reveals incommensurate order in the structure's channels. Here, two Zn sites associated with the channels are present, each with discontinuous atomic domains that are slanted in the x3x4 plane. Their slanting corresponds to adjustments along the c axis for the presence or absence of close neighbors along that axis, while the occupation patterns of neighboring channels are shifted by {1\over 3} of the modulation period. These features follow earlier predictions from CP analysis, highlighting how this approach can be used predictively in search of new phenomena.The superspace approach is used to determine the structure of a modulated form of YZn5+x (x = 0.217), which is an ordered variant of the previously described EuMg5+x-type structure, with its channels containing disordered Zn atoms. The details of the pattern align closely with earlier predictions based on DFT-chemical pressure analysis of ordered models.texthttps://creativecommons.org/licenses/by/4.0/Like many complex intermetallic phases, the crystal structures of REZn5+x compounds (RE = lanthanide or Group 3 element) based on the EuMg5 type have gradually unfolded. The original reports described a complex hexagonal structure with an unusual combination of tetrahedrally close-packed regions and open spaces, as well as observations of superstructure reflections. More recently, we reinvestigated the structure of YZn5, reclassifying it as the EuMg5+x-type compound YZn5+x (x ≃ 0.2), in which disordered channels run along c through the spaces formerly considered open. In addition, DFT-chemical pressure (DFT-CP) analysis of ordered models of YZn5+x highlighted paths for communication between neighboring channels setting the stage for superstructure formation. Herein, the experimental elucidation of this effect is presented with the synthesis and structure determination of a modulated form of YZn5+x. By slow-cooling samples of YZn5+x from the annealing temperature, crystals were obtained that exhibit satellite reflections with the modulation wavevector q = {1\over 3}a* + {1\over 3}b* + 0.3041c*. Structure solution and refinement using a (3+1)D model in superspace group P31c({1\over 3}\,\!{1\over 3}σ3)00s reveals incommensurate order in the structure's channels. Here, two Zn sites associated with the channels are present, each with discontinuous atomic domains that are slanted in the x3x4 plane. Their slanting corresponds to adjustments along the c axis for the presence or absence of close neighbors along that axis, while the occupation patterns of neighboring channels are shifted by {1\over 3} of the modulation period. These features follow earlier predictions from CP analysis, highlighting how this approach can be used predictively in search of new phenomena.APERIODIC CRYSTALS; CRYSTAL STRUCTURE PREDICTION; INTERMETALLIC PHASEStext/htmlenFredrickson, R.T.Fredrickson, D.C.urn:issn:2052-5206As predicted and more: modulated channel occupation in YZn5+xdoi:10.1107/S20525206230052922023-07-07International Union of CrystallographyActa Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papers794320August 20233292052-52062052-52062023-07-07https://creativecommons.org/licenses/by/4.0/med@iucr.orgA fresh view on the structure and twinning of owyheeite, a rod-polytype and twofold superstructure
http://scripts.iucr.org/cgi-bin/paper?ra5131
Owyheeite [Cu0.09 (1)Ag2.77 (4)Pb10.23 (4)Sb10.89 (5)S28.00 (5)] crystallizes as a twofold superstructure with P21/n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) Å, b = 27.2641 (7) Å, c = 22.8679 (7) Å, β = 90.293 (3)°, V = 5105.0 (3) Å3, Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (021). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles. A procedure of generating hypothetical polytypes by tiling space with partially overlapping equivalent regions is described.Owyheeite crystallizes as a twofold superstructure. The systematic twinning is due to the rod-polytype character of the structure.texthttps://creativecommons.org/licenses/by/4.0/Owyheeite [Cu0.09 (1)Ag2.77 (4)Pb10.23 (4)Sb10.89 (5)S28.00 (5)] crystallizes as a twofold superstructure with P21/n symmetry and pseudo-orthorhombic metrics [a = 8.1882 (3) Å, b = 27.2641 (7) Å, c = 22.8679 (7) Å, β = 90.293 (3)°, V = 5105.0 (3) Å3, Z = 4]. Owyheeite is systematically twinned by reflection at (021) or equivalently (021). Twinning is explained by describing a simplified Pmcn archetype structure as polytype built of two kinds of rods, which contact via electron-pair micelles. A procedure of generating hypothetical polytypes by tiling space with partially overlapping equivalent regions is described.MINERAL; SUPERSTRUCTURE; POLYTYPISM; TWINNINGtext/htmlenStöger, B.Göb, C.Topa, D.urn:issn:2052-5206A fresh view on the structure and twinning of owyheeite, a rod-polytype and twofold superstructuredoi:10.1107/S20525206230045232023-06-24International Union of Crystallographyresearch papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials280August 2023271479med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2023-06-242052-52062052-5206Synthesis and structure of two novel trans-platinum complexes
http://scripts.iucr.org/cgi-bin/paper?yv5009
Here for the first time the synthesis and characterization of two new trans-platinum complexes, trans-[PtCl2{HN=C(OH)C6H5}2] (compound 1) and trans-[PtCl4(NH3){HN=C(OH)tBu}] (compound 2) [with tBu = C(CH3)3] are described. The structures have been characterized using nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. In compound 1 the platinum cation, at the inversion center, is in the expected square-planar coordination geometry. It is coordinated to two chloride anions, trans to each other, and two nitrogen atoms from the benzamide ligands. The van der Waals interactions between the molecules produce extended two-dimensional layers that are linked into a three-dimensional structure through π⋯π intermolecular interactions. In compound 2 the platinum cation is octahedrally coordinated by four chloride anions and two nitrogen atoms from the pivalamide and ammine ligands, in trans configuration. The molecular packing is governed by intermolecular hydrogen bonds and van der Waals interactions.The synthesis and structural characterization (XRD and NMR) of two new trans-platinum complexes are presented.texthttps://creativecommons.org/licenses/by/4.0/Here for the first time the synthesis and characterization of two new trans-platinum complexes, trans-[PtCl2{HN=C(OH)C6H5}2] (compound 1) and trans-[PtCl4(NH3){HN=C(OH)tBu}] (compound 2) [with tBu = C(CH3)3] are described. The structures have been characterized using nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. In compound 1 the platinum cation, at the inversion center, is in the expected square-planar coordination geometry. It is coordinated to two chloride anions, trans to each other, and two nitrogen atoms from the benzamide ligands. The van der Waals interactions between the molecules produce extended two-dimensional layers that are linked into a three-dimensional structure through π⋯π intermolecular interactions. In compound 2 the platinum cation is octahedrally coordinated by four chloride anions and two nitrogen atoms from the pivalamide and ammine ligands, in trans configuration. The molecular packing is governed by intermolecular hydrogen bonds and van der Waals interactions.PLATINUM COMPLEXES; SYNTHESIS; ANTICANCER DRUGS; X-RAY DIFFRACTION; CRYSTAL STRUCTUREtext/htmlenVinci, D.Chateigner, D.urn:issn:2052-5206Synthesis and structure of two novel trans-platinum complexesdoi:10.1107/S205252062300327X2023-05-06International Union of CrystallographyJune 2023219793213Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papers2023-05-06https://creativecommons.org/licenses/by/4.0/med@iucr.org2052-52062052-5206Exploring the thermal behaviour of the solvated structures of nifedipine
http://scripts.iucr.org/cgi-bin/paper?aw5077
Understanding the solvation and desolvation of pharmaceutical materials is an important part of materials discovery and development. In situ structural data are vital to understand the changes to crystal form that may occur in the system. In this study, the isolation and characterization of seven solvates of the L-type calcium channel antagonist, nifedipine, is described using variable-temperature powder X-ray diffraction so that the structural evolution as a function of temperature can be followed. The solvates reported herein can be split into those that are structurally similar to the previously reported dimethyl sulfoxide (DMSO) and dioxane solvates and those that have a novel packing arrangement. Of particular note is the solvate with tetrahydrofuran (THF) which has a hydrogen-bonding motif between the nifedipine molecules very similar to that of metastable β-nifedipine. In addition to variable-temperature X-ray diffraction, the stability of the solid forms was assessed using differential scanning calorimetry and thermogravimetric analysis and indicates that in all cases desolvation results in the thermodynamically stable α-polymorph of nifedipine even with the THF solvate. From the diffraction data the pathway of desolvation during heating of the DMF solvate showed conversion to another likely 1:1 polymorph before desolvation to α-nifedipine. The desolvation of this material indicated a two-stage process; first the initial loss of 90% of the solvent before the last 10% is lost on melting. The methanol solvate shows interesting negative thermal expansion on heating, which is rarely reported in organic materials, but this behaviour can be linked back to the winerack-type hydrogen-bonding pattern of the nifedipine molecules.The formation of nifedipine solvates is explored and the desolvation pathways probed through a combination of variable-temperature X-ray powder diffraction, differential scanning calorimetry and thermal gravimetric analysis.texthttps://creativecommons.org/licenses/by/4.0/Understanding the solvation and desolvation of pharmaceutical materials is an important part of materials discovery and development. In situ structural data are vital to understand the changes to crystal form that may occur in the system. In this study, the isolation and characterization of seven solvates of the L-type calcium channel antagonist, nifedipine, is described using variable-temperature powder X-ray diffraction so that the structural evolution as a function of temperature can be followed. The solvates reported herein can be split into those that are structurally similar to the previously reported dimethyl sulfoxide (DMSO) and dioxane solvates and those that have a novel packing arrangement. Of particular note is the solvate with tetrahydrofuran (THF) which has a hydrogen-bonding motif between the nifedipine molecules very similar to that of metastable β-nifedipine. In addition to variable-temperature X-ray diffraction, the stability of the solid forms was assessed using differential scanning calorimetry and thermogravimetric analysis and indicates that in all cases desolvation results in the thermodynamically stable α-polymorph of nifedipine even with the THF solvate. From the diffraction data the pathway of desolvation during heating of the DMF solvate showed conversion to another likely 1:1 polymorph before desolvation to α-nifedipine. The desolvation of this material indicated a two-stage process; first the initial loss of 90% of the solvent before the last 10% is lost on melting. The methanol solvate shows interesting negative thermal expansion on heating, which is rarely reported in organic materials, but this behaviour can be linked back to the winerack-type hydrogen-bonding pattern of the nifedipine molecules.SOLVATE; DESOLVATION; NIFEDIPINE; PHARMACEUTICAL; VARIABLE-TEMPERATURE X-RAY DIFFRACTIONtext/htmlenJones, E.C.L.Goldsmith, K.E.Ward, M.R.Bimbo, L.M.Oswald, I.D.H.urn:issn:2052-5206Exploring the thermal behaviour of the solvated structures of nifedipinedoi:10.1107/S20525206230012822023-03-09International Union of Crystallography164279175April 2023research papersActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials2052-52062052-5206https://creativecommons.org/licenses/by/4.0/med@iucr.org2023-03-09Direct interpretation of the X-ray and neutron three-dimensional difference pair distribution functions (3D-ΔPDFs) of yttria-stabilized zirconia
http://scripts.iucr.org/cgi-bin/paper?ra5126
Three-dimensional difference pair distribution functions (3D-ΔPDFs) from X-ray and neutron diffraction experiments are reported for yttria-stabilized zirconia (Zr0.82Y0.18O1.91). A quantitative analysis of the signatures in the three-dimensional difference pair distribution functions is used to establish that oxygen ions neighbouring a vacancy shift by 0.525 (5) Å along 〈1, 0, 0〉 towards the vacancy while metal ions neighbouring a vacancy shift by 0.465 (2) Å along 〈1, 1, 1〉 away from the vacancy. The neutron 3D-ΔPDF shows a tendency for vacancies to cluster along 〈½, ½, ½〉, which results in sixfold coordinated metal ions.Three-dimensional difference pair distribution functions (3D-ΔPDFs) from X-ray and neutron diffraction experiments are used to identify local stabilization mechanisms in yttria-stabilized cubic zirconia.texthttps://creativecommons.org/licenses/by/4.0/Three-dimensional difference pair distribution functions (3D-ΔPDFs) from X-ray and neutron diffraction experiments are reported for yttria-stabilized zirconia (Zr0.82Y0.18O1.91). A quantitative analysis of the signatures in the three-dimensional difference pair distribution functions is used to establish that oxygen ions neighbouring a vacancy shift by 0.525 (5) Å along 〈1, 0, 0〉 towards the vacancy while metal ions neighbouring a vacancy shift by 0.465 (2) Å along 〈1, 1, 1〉 away from the vacancy. The neutron 3D-ΔPDF shows a tendency for vacancies to cluster along 〈½, ½, ½〉, which results in sixfold coordinated metal ions.DIFFUSE SCATTERING; CUBIC ZIRCONIA; THREE-DIMENSIONAL DIFFERENCE PAIR DISTRIBUTION FUNCTION (3D-[DELTA]PDF)text/htmlenSchmidt, E.M.Neder, R.B.Martin, J.D.Minelli, A.Lemée, M.-H.Goodwin, A.L.urn:issn:2052-5206Direct interpretation of the X-ray and neutron three-dimensional difference pair distribution functions (3D-ΔPDFs) of yttria-stabilized zirconiadoi:10.1107/S205252062300121X2023-02-24International Union of Crystallography2052-52062052-52062023-02-24https://creativecommons.org/licenses/by/4.0/med@iucr.orgActa Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papers792138April 2023147Incommensurate structures and radiation damage in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoites
http://scripts.iucr.org/cgi-bin/paper?dq5056
The structures and phase transitions to incommensurate structures in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoites are studied with synchrotron single-crystal diffraction at low temperatures and ambient pressure. Although mixed satellite reflections are absent, the modulated structure of K2V3O8 below 115 K is better described in (3 + 2)- than in (3 + 1)-dimensional space. The geometries of the VO4 and VO5 building units are rigid and it is mainly slight rotations of these polyhedra and small variation of the intermediate K—O distances that are modulated. Prolonged exposure to the high-brilliance synchrotron beam suppresses the incommensurate phase. The previously postulated phase transition to the incommensurate phase in Rb2V3O8 at 270 K was not observed. One of the reasons could be that the intense radiation also affects the modulation in this material. Strategies to collect and analyse single-crystal diffraction data measured with very intense synchrotron radiation using modern low-noise pixel area detectors are discussed.The structures and phase transitions to the incommensurate structures in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoites are studied with synchrotron single-crystal diffraction as a function of radiation dose at low temperatures and ambient pressure. Strategies to collect and analyse single-crystal diffraction data measured with very intense synchrotron radiation using modern low-noise pixel area detectors are discussed.texthttps://creativecommons.org/licenses/by/4.0/The structures and phase transitions to incommensurate structures in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoites are studied with synchrotron single-crystal diffraction at low temperatures and ambient pressure. Although mixed satellite reflections are absent, the modulated structure of K2V3O8 below 115 K is better described in (3 + 2)- than in (3 + 1)-dimensional space. The geometries of the VO4 and VO5 building units are rigid and it is mainly slight rotations of these polyhedra and small variation of the intermediate K—O distances that are modulated. Prolonged exposure to the high-brilliance synchrotron beam suppresses the incommensurate phase. The previously postulated phase transition to the incommensurate phase in Rb2V3O8 at 270 K was not observed. One of the reasons could be that the intense radiation also affects the modulation in this material. Strategies to collect and analyse single-crystal diffraction data measured with very intense synchrotron radiation using modern low-noise pixel area detectors are discussed.SYNCHROTRON RADIATION; SINGLE-CRYSTAL DIFFRACTION; INCOMMENSURATE STRUCTURES; RADIATION DAMAGEtext/htmlenGrzechnik, A.Petříček, V.Chernyshov, D.McMonagle, C.Geise, T.Shahed, H.Friese, K.urn:issn:2052-5206Incommensurate structures and radiation damage in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoitesdoi:10.1107/S20525206230009992023-02-17International Union of Crystallography2023-02-17med@iucr.orghttps://creativecommons.org/licenses/by/4.0/2052-52062052-5206Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materialsresearch papersApril 2023113791042