Zeitschriftenartikel: „Hydrated crystal“

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Zorin, Dmitriy, und Ivan Burlov. „Morphology of ettringite crystal of sulfoferrite clinker“. E3S Web of Conferences 244 (2021): 04008. http://dx.doi.org/10.1051/e3sconf/202124404008.

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This paper deals with the composition and properties of solid solution of calcium sulfoferrite. It was studied an influence of calcium s sulfoferrite on structure and properties cement phases. Study of the hydration processes of the calcium sulfoferrite mineral are observed only short prismatic crystals. Prismatic crystals of ferruginous ettringite are always formed from sulfoferrite mineral of any fraction. it was found that the smaller the initial hydrating grains of minerals, the faster they are hydrated. Analyse polyfractional compound hydration showed that fine fractions provide formation of crystallization centres, and particles less than 45 microns, with constant interaction with the liquid phase, cause a gradual growth of crystals. Expansion of hydrated minerals of certain fractions was analysed to check the dependence of the expansion on the morphology of ettringite crystal hydrates. During the hardening of the samples, expansion was observed along with a drop in strength.

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Oyama, Hironaga, Takashi Miyamoto, Akiko Sekine, Ilma Nugrahani und Hidehiro Uekusa. „Solid-State Dehydration Mechanism of Diclofenac Sodium Salt Hydrates“. Crystals 11, Nr. 4 (12.04.2021): 412. http://dx.doi.org/10.3390/cryst11040412.

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Salt formation is a useful technique for improving the solubility of active pharmaceutical ingredients (APIs). For instance, a nonsteroidal anti-inflammatory drug, diclofenac (DIC), is used in a sodium salt form, and it has been reported to form several hydrate forms. However, the crystal structure of the anhydrous form of diclofenac sodium (DIC-Na) and the structural relationship among the anhydrate and hydrated forms have not yet been revealed. In this study, DIC-Na anhydrate was analyzed using single-crystal X-ray diffraction (XRD). To determine the solid-state dehydration/hydration mechanism of DIC-Na hydrates based on both the present and previously reported crystal structures (4.75-hydrate and 3.5-hydrate), additional experiments including simultaneous powder XRD and differential scanning calorimetry, thermogravimetry, dynamic vapor sorption measurements, and a comparison of the crystal structures were performed. The dehydration of the 4.75-hydrate form was found to occur in two steps. During the first step, only water molecules that were not coordinated to Na+ ions were lost, which led to the formation of the 3.5-hydrate while retaining alternating layered structures. The subsequent dehydration step into the anhydrous phase accompanied a substantial structural reconstruction. This study elucidated the complete landscape of the dehydration/hydration transformation of DIC-Na for the first time through a crystal structure investigation. These findings contribute to understanding the mechanism underlying these dehydration/hydration phenomena and the physicochemical properties of pharmaceutical crystals.

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FÜREDI-MILHOFER, H., M. SIKIRIĆ, L. TUNIK, N. FILIPOVIĆ-VINCEKOVIĆ und N. GARTI. „INTERACTIONS OF ORGANIC ADDITIVES WITH IONIC CRYSTAL HYDRATES: THE IMPORTANCE OF THE HYDRATED LAYER“. International Journal of Modern Physics B 16, Nr. 01n02 (20.01.2002): 359–66. http://dx.doi.org/10.1142/s0217979202009871.

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The interactions of two groups of hydrated model crystals, calcium hydrogenphosphate dihydrate (DCPD) vs. octacalcium phosphate (OCP) and calcium oxalate monohydrate (COM) vs. calcium oxalate dihydrate (COD) with different organic additives are considered. DCPD precipitates as platelet-like crystals with the dominant faces shielded by hydrated layers and charged lateral faces. In the second system COM has charged surfaces, while all faces of COD are covered with layers containing water molecules. The organic molecules tested include negatively charged, flexible and rigid small and macromolecules (glutamic and aspartic acid, citrate, hexaammonium polyphosphate, phytate and polyaspartate) and anionic surfactants (sodium dodecyl sulphate, SDS, sodium diisooctyl sulfosuccinate, AOT, sodium cholate NaC and disodium oleoamido PEG-2 sulfosuccinate, PEG). Two types of effects have been demonstrated: (1) Effect on crystal growth morphology: Flexible organic molecules with high charge density and anionic surfactants affected the growth morphology of DCPD and COM by selectively interacting with the charged lateral faces while rigid molecules (phytate, polyaspartate) specifically recognized the dominant (010) face of DCPD due to structural and stereochemical compatibility. (2) Effect on phase composition: Anionic surfactants at concentrations above the cmc promoted growth of OCP and COD respectively by selectively adsorbing at, and inhibiting growth oif nuclei of DCPD and/or COM, which were dominant in the respective control systems. The effect was especially pronounced in the calcium oxalate precipitation system, where in some cases complete reversal of the phase composition occurred. The important role of the hydrated layer, as part of the structure of the investigated crystal hydrates, in the above crystal additive interactions is discussed.

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Braun, Doris, und Ulrich Griesser. „Insights into hydrate formation and stability of morphinanes“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C991. http://dx.doi.org/10.1107/s2053273314090081.

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The formation of multi-component crystals with water (hydrates) is a widespread phenomenon among organic molecules. Hydrate formation is of high practical relevance for industrially used materials, as it affects their physicochemical properties. [1,2] To exclude water or moisture in industrial processes is often difficult. Therefore knowledge about the existence and stability of hydrates and the understanding and control of the anhydrate/hydrate balance is mandatory for avoiding manufacturing problems. In order to improve our understanding of hydrate formation we selected representative substances (morphine, codeine, ethylmorphine) from a class of molecules (morphinanes), which are prone to crystallize along with water. Stable hydrates of both, free bases and HCl salts, have been observed in this important class of drug compounds. This allowed us to investigate the influence of different functional groups, the role of water and the Cl– counterion on the structure and properties of these morphinanes. A crystallization screen on the six compounds considerably extended the total number of known solid forms from twelve [3] to 17 and the number of crystal structures from five to twelve. Anhydrous polymorphs were detected for all compounds except ethylmorphine (one anhydrate) and its HCl salt (no anhydrate). The relative stabilities of the hydrated and anhydrous forms differ considerably, which was evaluated by moisture sorption studies and thermal analytical experiments. Two different hydrates, a tri- and dihydrate, were found for morphine HCl. In the free bases, the substituents define the number of hydrogen bond donor groups and lead to differences in the sterical hindrance around polar groups, influencing the intermolecular interactions, packing and stability. Hydrate formation results in higher dimensional hydrogen bond networks, whereas salt formation decreases the packing variability of the structures among the different compounds. Calorimetric measurements and lattice energy calculations were employed to estimate the heat of hydrate/anhydrate phase transformation, showing an enthalpic stabilization of the hydrates over the anhydrates. The combination of a variety of experimental techniques with computational modelling allowed us to generate sufficient kinetic, thermodynamic and structural information to understand the principles of hydrate formation of morphinanes.

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Zhang, Ziming, Qiang Cai, Jiadan Xue, Jianyuan Qin, Jianjun Liu und Yong Du. „Co-Crystal Formation of Antibiotic Nitrofurantoin Drug and Melamine Co-Former Based on a Vibrational Spectroscopic Study“. Pharmaceutics 11, Nr. 2 (30.01.2019): 56. http://dx.doi.org/10.3390/pharmaceutics11020056.

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The co-crystallization of active pharmaceutical ingredients (APIs) has received increasing attention due to the modulation of the relative physicochemical properties of APIs such as low solubility, weak permeability and relatively inferior oral bioavailability. Crystal engineering plays a decisive role in the systematic design and synthesis of co-crystals by means of exerting control on the inter-molecular interactions. The characterization and detection of such co-crystal formations plays an essential role in the field of pharmaceutical research and development. In this work, nitrofurantoin (NF), melamine (MELA) and their hydrated co-crystal form were characterized and analyzed by using terahertz time-domain spectroscopy (THz-TDS) and Raman vibrational spectroscopy. According to the experimental THz spectra, the hydrated co-crystal form has characteristic absorption peaks at 0.67, 1.05, 1.50 and 1.73 THz, while the THz spectra for the two raw parent materials (NF and MELA) are quite different within this spectral region. Similar observations were made from the experimental Raman vibrational spectra results. Density functional theory (DFT) calculation was performed to help determine the major vibrational modes of the hydrated co-crystal between nitrofurantoin and melamine, as well as identify the structural changes due to inter- and/or intra-molecular hydrogen bonding motifs between NF and MELA. The results of the theoretical frequency calculations corroborate the THz and Raman experimental spectra. The characteristic bands of the NF–MELA-hydrated co-crystal between nitrofurantoin and melamine were also determined based on the DFT simulated calculation. The reported results in this work provide us with a wealth of structural information and a unique vibrational spectroscopic method for characterizing the composition of specific co-crystals and inter-molecular hydrogen bonding interactions upon pharmaceutical co-crystallization.

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Kersten, Kortney, Ramanpreet Kaur und Adam Matzger. „Survey and analysis of crystal polymorphism in organic structures“. IUCrJ 5, Nr. 2 (25.01.2018): 124–29. http://dx.doi.org/10.1107/s2052252518000660.

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With the intention of producing the most comprehensive treatment of the prevalence of crystal polymorphism among structurally characterized materials, all polymorphic compounds flagged as such within the Cambridge Structural Database (CSD) are analysed and a list of crystallographically characterized organic polymorphic compounds is assembled. Classifying these structures into subclasses of anhydrates, salts, hydrates, non-hydrated solvates and cocrystals reveals that there are significant variations in polymorphism prevalence as a function of crystal type, a fact which has not previously been recognized in the literature. It is also shown that, as a percentage, polymorphic entries are decreasing temporally within the CSD, with the notable exception of cocrystals, which continue to rise at a rate that is a constant fraction of the overall entries. Some phenomena identified that require additional scrutiny include the relative prevalence of temperature-induced phase transitions among organic salts and the paucity of polymorphism in crystals with three or more chemical components.

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Zimakova, Galina, Valentina Solonina, Marina Zelig und Viktor Orlov. „Effect of fine-grained components on concrete properties and structure formation“. MATEC Web of Conferences 143 (2018): 02004. http://dx.doi.org/10.1051/matecconf/201814302004.

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The paper investigates the influence of fine-grained components on the synthesis of new formations and structure of cellular concrete. Grain size composition was defined with the aid of a laser diffraction analyzer of particles ANALYSETTE 22 NanoTecplus. The composition of the obtained hydrated phases was studied using electron microscopy and X-ray phase analysis. The introduction of silica and aluminosilicate components with the specific surface area >350 m2/kg enabled to directly influence the mechanism of the hydrated phases formation. Complex hydrated calcium aluminosilicates of the frame structure of zeolite type and non-permanent composition were identified in the hydration products. The formation of the total set of properties is attributed to the morphological features of the hydrated phases, the nature of connections between the crystalline hydrates, and their location in the material structure. X-ray phase analysis showed that ultra-micro-dispersed components have the stimulating impact on the processes of silicate formation. With the increase in the amount of hydrated new formations and decrease in the liquid phase volume the conditions for building of strong crystal intergrowth contacts were created.

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Bétourné, E., und M. Touboul. „Crystallographic data about hydrated and anhydrous lithium monoborates“. Powder Diffraction 12, Nr. 3 (September 1997): 155–59. http://dx.doi.org/10.1017/s0885715600009635.

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The anhydrous and hydrated lithium monoborates have been studied. The most hydrated phase is LiBO2·8H2O; its structural formula in the P3 space group is Li(H2O)4B(OH)4·2H2O. Refinement of the cell parameters yielded the following results: a=6.5483(5) Å, c=6.1692(7) Å with F(30)=64(0.015, 32), Z=1, and Dx=1.402 g/cm3. This phase gives LiB(OH)4 by spontaneous dehydration. An X-ray powder diffraction study of LiB(OH)4 as a function of temperature indicated three poorly crystallized hydrates. Two of these hydrates have the formula LiBO2·0.3H2O; the other, LiBO2·xH2O, has an undetermined water content. Crystal data for α-LiBO2 have been obtained: a=5.8473(10) Å, b=4.3513(6) Å, c=6.4557(10) Å, β=115.08(1)°, F(27)=58.5(0.001, 41); space group P21/c, Z=4, and Dx=2.18 g/cm3. β-LiBO2 does not exist but corresponds to the α-LiBO2 form observed at 600 °C. Numerous other LiBO2 forms reported recently have not been found.

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Gallois-Montbrun, Delphine, Geneviève Le Bas, Sax A. Mason, Thierry Prangé und Sylviane Lesieur. „A highly hydrated α-cyclodextrin/1-undecanol inclusion complex: crystal structure and hydrogen-bond network from high-resolution neutron diffraction at 20 K“. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 69, Nr. 2 (26.02.2013): 214–27. http://dx.doi.org/10.1107/s2052519213001772.

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The monoclinicC2 crystal structure of an α-cyclodextrin/1-undecanol host–guest inclusion complex was solved using single-crystal neutron diffraction. Large high-quality crystals were specially produced by optimizing temperature-controlled growth conditions. The hydrate crystallizes in a channel-type structure formed by head-to-head dimer units of α-cyclodextrin molecules stacked like coins in a roll. The alkyl chain of the guest lipid is entirely embedded inside the tubular cavity delimited by the α-cyclodextrin dimer and adopts an all-transplanar zigzag conformation, while the alcohol polar head group is outside close to the α-cyclodextrin primary hydroxyl groups. The cyclodextrin dimer forms columns, which adopt a quasi-square arrangement much less compact than the quasi-hexagonal close packing already observed in the less hydrated α-cyclodextrin channel-type structures usually found with similar linear guests. The lack of compactness of this crystal form is related to the high number of interstitial water molecules. The replacement of 1-undecanol by 1-decanol does not modify the overall crystal structure of the hydrate as shown by additional X-ray diffraction investigations comparing the two host–guest assemblies. This is the first study that analyses the entire hydrogen-bonding network involved in the formation of a cyclodextrin dimer surrounded by its shell of water molecules.

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Mackay, Maureen F., Robert W. Gable, James D. Morrison und Lothar O. Satzke. „Structure of Hydrated Copper(II) Colchiceine“. Australian Journal of Chemistry 52, Nr. 4 (1999): 333. http://dx.doi.org/10.1071/c98162.

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Hydrated crystals of copper(II) colchiceine belong to the tetragonal space group P 432I2 with a 13·415(1), c 50·169(8) Å and Z 8. The structure has been refined to a conventional R factor of 0·077 for 4560 observed data. The tropolonic oxygens from two colchiceine molecules are coordinated to the copper atom in this bis-chelated complex to form a square planar arrangement. The sites of three of the waters are clearly defined, but the others are disordered over seven partially occupied sites. An intricate hydrogen-bonding system links the complex and water molecules into a three-dimensional network in the crystal.

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Ferná ndez-Carrasco, Lucia, und Jordi Rius. „Synthesis and crystal structure determination of hydrated potassium dawsonite from powder diffraction data“. European Journal of Mineralogy 18, Nr. 1 (06.03.2006): 99–104. http://dx.doi.org/10.1127/0935-1221/2006/0018-0099.

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Kildea, JD, BW Skelton und AH White. „Crystallographic Characterization of a Hydrated Form of Copper(I) Cyanide“. Australian Journal of Chemistry 38, Nr. 9 (1985): 1329. http://dx.doi.org/10.1071/ch9851329.

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The crystal structure of a crystalline artefact of a reaction involving copper(I), cyanide and water under conditions of high temperature and pressure has been determined by single-crystal X-ray diffraction methods at 295 K, and refined by full matrix least-squares to a residual of 0.046 for 572 independent 'observed' reflections; the composition is suggested to be [Cu3(CN)3(H2O)]∞, comprising a two- dimensional polymer with both linearly coordinated and bridging cyanide groups. Crystals are monoclinic, probable space group C2/c, a 19.048(7), b 6.798(3), c 13.223(7) Ǻ, β 125.72(3)°, Z 8.

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Duyvesteyn, Helen M. E., Abhay Kotecha, Helen M. Ginn, Corey W. Hecksel, Emma V. Beale, Felix de Haas, Gwyndaf Evans, Peijun Zhang, Wah Chiu und David I. Stuart. „Machining protein microcrystals for structure determination by electron diffraction“. Proceedings of the National Academy of Sciences 115, Nr. 38 (31.08.2018): 9569–73. http://dx.doi.org/10.1073/pnas.1809978115.

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We demonstrate that ion-beam milling of frozen, hydrated protein crystals to thin lamella preserves the crystal lattice to near-atomic resolution. This provides a vehicle for protein structure determination, bridging the crystal size gap between the nanometer scale of conventional electron diffraction and micron scale of synchrotron microfocus beamlines. The demonstration that atomic information can be retained suggests that milling could provide such detail on sections cut from vitrified cells.

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BăDilescu, Simona, und Camille Sandorfy. „Freeze-Drying Fourier Transform Infrared Attenuated Total Reflection Spectroscopy of Surface Adsorbed Layers. Hydration of Adenosine-5'-Phosphoric Acid“. Applied Spectroscopy 41, Nr. 1 (Januar 1987): 10–15. http://dx.doi.org/10.1366/0003702874868098.

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A new methodology, suitable for spectral measurements on polar, biologically important molecules, has been developed. The capability of the thallium bromide iodide ATR crystal to adsorb water has been examined and the hydrated crystal surface was used as a substrate for the adsorbed molecules. Diagnostic bands for adsorbed water are reported. A freeze-drying procedure was used to adsorb adenosine-5'-phosphate molecules on the hydrated ATR crystal, and FT-IR spectra of the system were recorded. Different hydrated species of adenosine-5'-monophosphate adsorbed on a water-screened ATR crystal have been observed. The broad bands at 935, 950, and 970 cm−1 are assigned to phosphate groups adsorbed on the thallium bromide-iodide crystal screened by low, medium, and high water coverage, respectively. The high sensitivity of the method is emphasized. The proposed ATR method may be useful for the study of membrane-associated phenomena and models of real-life biological systems with a low solute concentration.

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Silva, Manuela Ramos, Ana Matos Beja, Benilde F. O. Costa, José A. Paixão und Luiz Alte da Veiga. „Crystal structure of hydrated diphenylguanidinium hexafluoroferrate (III)“. Journal of Fluorine Chemistry 106, Nr. 1 (Oktober 2000): 77–81. http://dx.doi.org/10.1016/s0022-1139(00)00312-2.

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Okuyama, Kenji, Keiichi Noguchi, Takashi Miyazawa, Toshifumi Yui und Kozo Ogawa. „Molecular and Crystal Structure of Hydrated Chitosan“. Macromolecules 30, Nr. 19 (September 1997): 5849–55. http://dx.doi.org/10.1021/ma970509n.

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Sjögren, Tove, Gunilla Carlsson, Gisela Larsson, Andras Hajdu, Christer Andersson, Hans Pettersson und Janos Hajdu. „Protein crystallography in a vapour stream: data collection, reaction initiation and intermediate trapping in naked hydrated protein crystals“. Journal of Applied Crystallography 35, Nr. 1 (22.01.2002): 113–16. http://dx.doi.org/10.1107/s0021889801020702.

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A procedure is presented for experiments on naked unfrozen protein crystals with the crystal mounted in a conventional cryo-loop and surrounded by a stream of a wet gas. The composition and temperature of the vapour stream can be adjusted to keep the crystal without deterioration for many hours. The arrangement allows (i) for rapidly testing crystals for diffraction before freezing, (ii) for data collection between 268–303 K with greatly reduced background, (iii) for the controlled drying or wetting of crystals, (iv) for the anaerobic manipulation of protein crystals, and (v) for the introduction of gaseous or volatile ingredients and reactants into the crystal. The technique offers new experimental possibilities,e.g.in time-resolved structural studies. Reaction initiation in many protein crystals can be achieved by changing the composition of the vapour stream to create a new chemical environment around the crystal and to introduce substrates/reactants either in the gas phase or as microdroplets. Spectral changes during such reactions can be monitored by single-crystal microspectrophotometry, and, once an intermediate has been detected at high concentrations, the crystal can be frozen,e.g.by rapidly switching the warm vapour stream to a cryogenically cooled helium or nitrogen jet. Representative examples are presented in this paper.

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Kumberger, Otto, Jürgen Riede und Hubert Schmidbaur. „Preparation and Crystal Structure of Zinc Bis[orotate(1–)] Octahydrate“. Zeitschrift für Naturforschung B 48, Nr. 7 (01.07.1993): 961–64. http://dx.doi.org/10.1515/znb-1993-0718.

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A discrete zinc bis[orotate(1—)] complex of the composition Zn(OrH)2·8 H2O has been isolated and characterized by a single-crystal X-ray structure analysis. The crystals are monoclinic, space group P21/c (No. 14), Z = 2, a = 10.884(2), b = 12.896(1), c = 6.954(1) Å, β = 98.27(1)°. The crystal lattice features hexaquo complexes of zinc, the Zn(H2O)62+ cations being associated with two hydrated OrH- ions only through hydrogen bonds. The results are relevant for applications of zinc orotates in medical treatment.

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Klein, Wilhelm. „Crystal structures of the penta- and hexahydrate of thulium nitrate“. Acta Crystallographica Section E Crystallographic Communications 76, Nr. 12 (24.11.2020): 1863–67. http://dx.doi.org/10.1107/s2056989020015388.

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Tm(NO3)3·5H2O and Tm(NO3)3·6H2O, or more precisely [Tm(NO3)3(H2O)4]·H2O and [Tm(NO3)3(H2O)4]·2H2O, respectively, have been obtained from a concentrated solution of Tm2O3 in HNO3. The crystal structures of the two hydrates show strong similarities as both crystallize in space group P\overline{1} with all atoms at general positions and contain neutral, molecular [Tm(NO3)3(H2O)4] complexes, i.e. ten-coordinated TmIII cations with three nitrate anions as bidentate ligands and four coordinating water molecules, and one or two additional crystal water molecules, respectively. All building units are connected by medium–strong to weak O—H...O hydrogen bonds. Tm(NO3)3·6H2O represents the maximally hydrated thulium nitrate as well as the heaviest rare earth nitrate hexahydrate known to date.

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Braga, Dario, Fabrizia Grepioni, Giulio I. Lampronti, Lucia Maini, Katia Rubini, Alessandro Turrina und Federico Zorzi. „Crystal form selectivity by humidity control: the case of the ionic co-crystals of nicotinamide and CaCl2“. CrystEngComm 16, Nr. 32 (2014): 7452–58. http://dx.doi.org/10.1039/c4ce00464g.

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Connolly, Jon H., und Jody Jellison. „Calcium translocation, calcium oxalate accumulation, and hyphal sheath morphology in the white-rot fungus Resinicium bicolor“. Canadian Journal of Botany 73, Nr. 6 (01.06.1995): 927–36. http://dx.doi.org/10.1139/b95-101.

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The white-rot fungus Resinicium bicolor was cultured on wood blocks in a modified soil block assay and was observed by environmental scanning electron microscopy and scanning electron microscopy. Resinicium bicolor was found to translocate calcium in mycelial cords in quantities greater than that found in the wood blocks and accumulated this calcium in the form of calcium oxalate. Calcium oxalate crystal clusters of mycelial cords were 3 × larger and far more numerous than the crystal clusters produced by the same fungus within the wood. Environmental scanning electron microscopy technology allowed for the examination of the hyphal sheath in a hydrated state. The hydrated hyphal sheath was found to be much thicker than the desiccated sheath observed after standard scanning electron microscope preparations. Calcium oxalate crystals were found to be embedded in the thick hyphal sheath, suggesting that previous observations of within-wall calcium oxalate precipitation may perhaps be better interpreted as artifacts generated during sample preparation. Key words: calcium oxalate, hyphal sheath, environmental scanning electron microscopy.

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Gras, Pierre, Nicolas Ratel-Ramond, Sébastien Teychéné, Christian Rey, Erik Elkaim, Béatrice Biscans, Stéphanie Sarda und Christèle Combes. „Structure of the calcium pyrophosphate monohydrate phase (Ca2P2O7·H2O): towards understanding the dehydration process in calcium pyrophosphate hydrates“. Acta Crystallographica Section C Structural Chemistry 70, Nr. 9 (09.08.2014): 862–66. http://dx.doi.org/10.1107/s2053229614017446.

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Calcium pyrophosphate hydrate (CPP, Ca2P2O7·nH2O) and calcium orthophosphate compounds (including apatite, octacalcium phosphateetc.) are among the most prevalent pathological calcifications in joints. Even though only two dihydrated forms of CPP (CPPD) have been detectedin vivo(monoclinic and triclinic CPPD), investigations of other hydrated forms such as tetrahydrated or amorphous CPP are relevant to a further understanding of the physicochemistry of those phases of biological interest. The synthesis of single crystals of calcium pyrophosphate monohydrate (CPPM; Ca2P2O7·H2O) by diffusion in silica gel at ambient temperature and the structural analysis of this phase are reported in this paper. Complementarily, data from synchrotron X-ray diffraction on a CPPM powder sample have been fitted to the crystal parameters. Finally, the relationship between the resolved structure for the CPPM phase and the structure of the tetrahydrated calcium pyrophosphate β phase (CPPT-β) is discussed.

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Neogy, D., A. K. Mukherjee und T. Purohit. „Calculation of electrostatic crystal field parameters of rare earth hydrated single crystals“. Physica Status Solidi (a) 106, Nr. 1 (16.03.1988): 173–80. http://dx.doi.org/10.1002/pssa.2211060121.

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Viriyarattanasak, Chotika, Motoo Shiro, Shigeru Munekawa, Felix Franks, Satomi Ikeda und Kazuhito Kajiwara. „Dehydration of raffinose pentahydrate: structures of raffinose 5-, 4.433-, 4.289- and 4.127-hydrate at 93 K“. Acta Crystallographica Section C Structural Chemistry 71, Nr. 11 (13.10.2015): 954–58. http://dx.doi.org/10.1107/s2053229615017374.

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Raffinose [orO-α-D-galactopyranosyl-(1→6)-α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside] pentahydrate, C18H32O16·5H2O, (I), and three lower hydrates, namely the 4.433-, (II), 4.289-, (III), and 4.127-hydrated, (IV), forms, obtained in the course of the dehydration of (I), have been studied. The unit cells in the space groupP212121are of similar dimensions for all the crystals. The conformation of the raffinose molecules remains almost the same across the four crystal structures. The raffinose molecules are linked into a three-dimensional hydrogen-bonded network involving all the –OH groups, the ring and glycosidic O atoms, and the water molecules. Six water sites were identified in the structures of (II), (III) and (IV), of whichW1,W4 andW6 (W= water) are partially occupied with their populations coupled.W1,W4 and one of the –OH groups of the galactose ring form an infinite hydrogen-bonding chain around a 21axis parallel to theaaxis (denoted chainA), andW6 and the same –OH group form a similar chain (chainA′) disordered with chainA. The occupancy ratio of chainAto chainA′ forN-hydrates (Nis a hydration number between 4 and 5) is (N− 4):(5 −N). The transformation of chainAto chainA′ as part of the dehydration process has little effect on the rest of the structure. Thus, the dehydration proceeds without significant impact on the crystal structure.

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Kasthuri, V. Bangera, P. Mohan Rao und M. Nethaji. „The Crystal Structure of Hydrated Barium Copper Oxalate“. Crystal Research and Technology 31, Nr. 3 (1996): 287–94. http://dx.doi.org/10.1002/crat.2170310305.

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Zhang, Guanqun, Yaqi Fan, Ju Huang, Lijin Wang, Chengguang Yang, Meng Lyu, Haiming Liu und Yanhang Ma. „Decoupling nucleation from crystal-growth for the synthesis of nanocrystalline zeolites“. Dalton Transactions 49, Nr. 21 (2020): 7258–66. http://dx.doi.org/10.1039/d0dt01291b.

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Tan, Zeqing, Jian Zhao, Jingzhi Sun, Jiaxin Zhao, Xinrui He, Zhe Liu, Lin Zhu, Xiao Cheng und Chuanjian Zhou. „CHCl3-Dependent Emission Color and Jumping Behavior of Cyclic Chalcone Single Crystals: The Halogen Bond Network Effect“. Crystals 11, Nr. 5 (11.05.2021): 530. http://dx.doi.org/10.3390/cryst11050530.

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As a conventional strategy to modulate the structure and properties of inorganic single crystals, hydration/solvation is rarely found to function in pure organic single crystal. Herein, we report chalcone single crystals with CHCl3-dependent emission color and jumping behavior. Two crystals: a pure crystal phase (1) with green-yellow emission and a CHCl3-containing co-crystal phase (1•2CHCl3) with orange-red emission were constructed by fine-controlling the crystallization conditions. The special halogen bond network in the crystal packing structure effectively narrows the bandgap and thereby redshift the emission of 1•2CHCl3. 1•2CHCl3 would revert to 1 together with emission color change when losing CHCl3. These findings are similar to the effect of H2O in hydrated inorganic crystals. Notably, owing to a special pre-organized “molecular pair” structure for [2 + 2] cycloaddition, the pure crystal phase 1 exhibits violently photo-induced jumping phenomenon, indicating large potentials in intelligent devices. This work would overturn the previous perception that the structurally simple solvent molecules without conjugation cannot greatly affect the structure and properties of pure organic single crystals and provide a new strategy to construct multi-colored organic fluorescent crystals.

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Mobin, Shaikh M., Ashwini K. Srivastava, Pradeep Mathur und Goutam Kumar Lahiri. „Single-crystal to single-crystal transformations in discrete hydrated dimeric copper complexes“. Dalton Trans. 39, Nr. 6 (2010): 1447–49. http://dx.doi.org/10.1039/b918761h.

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Fulford, Mabel V., Alan John Lough und Timothy P. Bender. „The first report of the crystal structure of non-solvated μ-oxo boron subphthalocyanine and the crystal structures of two solvated forms“. Acta Crystallographica Section B Structural Science 68, Nr. 6 (16.11.2012): 636–45. http://dx.doi.org/10.1107/s0108768112037184.

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The first instance of the solvent-free X-ray determined single-crystal structure of the oxygen-bridged boron subphthalocyanine dimer [μ-oxo-(BsubPc)2, C48H24B2N12O] is reported. Single crystals obtained by train sublimation were found to have μ-oxo-(BsubPc)2 organized into a C2/c space group. The crystal structure obtained by sublimation is of particular interest as it is highly symmetric and also of notably high density when compared with other BsubPc crystals. The acquisition of this crystal structure came about from the direct chemical synthesis of μ-oxo-(BsubPc)2 followed by a work-up which culminated in obtaining the single crystals by sublimation. Several methods for the direct chemical synthesis of μ-oxo-(BsubPc)2 were also investigated each using dichlorobenzene as the solvent. On standing, these reaction mixtures produced a crystal of the dichlorobenzene (DCB) solvate of μ-oxo-(BsubPc)2 [μ-oxo-(BsubPc)2·2DCB]. It is also reported that the conversion of bromo-boron subphthalocyanine (Br-BsubPc) to μ-oxo-(BsubPc)2 happens on train sublimation which resulted in the acquisition of a partially hydrated crystal [μ-oxo-(BsubPc)2·0.25H2O].

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Quartieri, Simona, Maurizio Triscari und Alberto Viani. „Crystal structure of the hydrated sulphate pickeringite (MgAl2(SO4)4· 22H2O): X-ray powder diffraction study“. European Journal of Mineralogy 12, Nr. 6 (17.11.2000): 1131–38. http://dx.doi.org/10.1127/ejm/12/6/1131.

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31

Wang, Feng, Pingan Chen, Xiangcheng Li und Boquan Zhu. „Effect of Colloidal Silica on the Hydration Behavior of Calcium Aluminate Cement“. Materials 11, Nr. 10 (28.09.2018): 1849. http://dx.doi.org/10.3390/ma11101849.

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The effect of colloidal silica (CS) on the hydrate phases and microstructure evolution of calcium aluminate cement (CAC) was investigated. Samples hydrated with CS were obtained and characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared spectroscopy (FT-IR), hydration heat measurement and Nuclear Magnetic Resonance (NMR). The results revealed that SiO2 nanoparticles may affect the hydrates crystallization process. There was a compact structure in the CAC paste with CS, while petal-shaped hydrates with a porous structure were formed in the pure CAC paste. The maximum value of electrical conductivity for CAC paste with CS suggested that the early stage of hydration for CAC was accelerated. However, the hydration heat curves revealed that the late stage of the CAC hydration process was inhibited, and the hydration degree was reduced, this result was in accordance with Thermogravimetry-Differential scanning calorimetry(TG-DSC) curves. The fitting results of hydration heat curves further showed that the hydration degree at NG (nucleation and crystal growth) process stage was promoted, while it was limited at the phase boundaries stage, and the diffusion stage in the hydration reaction was brought forward due to the addition of CS. According to these results and analyses, the differences in the hydration process for CAC with and without CS can be attributed to the distribution and nucleation effect of SiO2 nanoparticles.

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Bilton, Clair, Judith A. K. Howard, N. N. L. Madhavi, Gautam R. Desiraju, Frank H. Allen und Chick C. Wilson. „Crystal engineering in the gem-alkynol family: the key role of water in the structure of 2,3,5,6-tetrabromo-trans-1,4-diethynyl-cyclohexa-2,5-diene-1,4-diol dihydrate determined by X-ray and neutron diffraction at 150 K“. Acta Crystallographica Section B Structural Science 57, Nr. 4 (24.07.2001): 560–66. http://dx.doi.org/10.1107/s0108768101008412.

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The structure of the title compound has been determined using low-temperature (150 K) single-crystal X-ray and neutron diffraction data. Crystals adopt the uncommon space group P42/ncm and display a complex set of intermolecular interactions in which the water molecules play the crucial role: the water O-atom [O2(w)] accepts two hydrogen bonds and both water H atoms act as bifurcated donors. A set of O—H...O hydrogen bonds is formed around the 42 axis comprising (a) a cyclic tetrameric synthon involving four donor-H from two water molecules and two O(hydroxy) acceptors from two parent molecules, and (b) short discrete O(hydroxy)—H...O2(w) hydrogen bonds which link these tetramers along the c axis. Four Br...Br interactions [3.708 (1) Å] form cyclic Br4 tetramers around the \bar 4 axis and are linked to the O—H...O system via O2(w)—H...Br bonds with H...Br = 2.995 (2) Å. Finally, the O—H...O system is further linked to the parent molecules via C≡C...H...O2(w) bonds of 2.354 (3) Å. The supramolecular structure of the title hydrate is compared with that of the non-hydrated parent molecule, which also forms cyclic O—H...O bonded tetrameric synthons, and with its (non-hydrated) tetrachloro analogue, which forms cyclic tetrameric Cl4 synthons [Madhavi, Desiraju et al. (2000b). Acta Cryst. B56, 1063–1070].

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Kim, Chae Un, Jennifer L. Wierman, Richard Gillilan, Enju Lima und Sol M. Gruner. „A high-pressure cryocooling method for protein crystals and biological samples with reduced background X-ray scatter“. Journal of Applied Crystallography 46, Nr. 1 (21.12.2012): 234–41. http://dx.doi.org/10.1107/s0021889812045013.

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High-pressure cryocooling has been developed as an alternative method for cryopreservation of macromolecular crystals and successfully applied for various technical and scientific studies. The method requires the preservation of crystal hydration as the crystal is pressurized with dry helium gas. Previously, crystal hydration was maintained either by coating crystals with a mineral oil or by enclosing crystals in a capillary which was filled with crystallization mother liquor. These methods are not well suited to weakly diffracting crystals because of the relatively high background scattering from the hydrating materials. Here, an alternative method of crystal hydration, called capillary shielding, is described. The specimen is kept hydratedviavapor diffusion in a shielding capillary while it is being pressure cryocooled. After cryocooling, the shielding capillary is removed to reduce background X-ray scattering. It is shown that, compared to previous crystal-hydration methods, the new hydration method produces superior crystal diffraction with little sign of crystal damage. Using the new method, a weakly diffracting protein crystal may be properly pressure cryocooled with little or no addition of external cryoprotectants, and significantly reduced background scattering can be observed from the resulting sample. Beyond the applications for macromolecular crystallography, it is shown that the method has great potential for the preparation of noncrystalline hydrated biological samples for coherent diffraction imaging with future X-ray sources.

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Li, Xuerun, Ruben Snellings und Karen L. Scrivener. „Quantification of amorphous siliceous fly ash in hydrated blended cement pastes by X-ray powder diffraction“. Journal of Applied Crystallography 52, Nr. 6 (08.11.2019): 1358–70. http://dx.doi.org/10.1107/s1600576719013955.

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X-ray powder diffraction (XRPD)-based quantitative phase analysis is a common technique for studying the hydration of cementitious systems. Hydrated cements often comprise several amorphous or nanocrystalline phases. This paper presents a protocol for the quantification of amorphous siliceous fly ash in hydrated cement using XRPD based on the Rietveld PONKCS (partial or no known crystal structure) method. The protocol is validated by comparison against independent measurements, such as Ca(OH)2 content by thermogravimetry and isothermal calorimetry to evaluate the fly ash degree of reaction. A sensitivity analysis of the protocol was carried out to test the robustness of the results with regard to sample preparation, data collection strategies and refinement model parameters. The key sensitive aspects of the protocol are (i) the preservation and preparation of the hydrated cement sample for XRPD measurement, (ii) the selection of a 2θ angular range for the Rietveld analysis that avoids low-angle scattering interferences, and (iii) the use of the peak profile to account for the contribution of other amorphous phases such as the diffraction pattern of nanocrystalline calcium silicate hydrate (C–S–H). The results show good accuracy in terms of quantification if the initial fly ash content is more than 10 wt%. Example TOPAS fly ash and C–S–H codes, as well as the raw XRPD data set, are provided.

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Akriche, Samah, Aymen Tliba und Mohamed Rzaigui. „Crystal Growth and Characterization of the Non-Centrosymmetric Hydrated Co-hexaborate templated by racemic 2-methylpiperazinium (C5H14N2){Co[B6O7(OH)6]2}.2H2O“. JOURNAL OF ADVANCES IN CHEMISTRY 10, Nr. 3 (04.04.2014): 2377–87. http://dx.doi.org/10.24297/jac.v10i3.2288.

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Large single crystals of the non-centrosymmetric hydrated Co-hexaborate (C5H14N2){Co[B6O7(OH)6]2}.2H2O were grown from aqueous solution and characterized by powder and single-crystal XRD methods, IR, UV-Vis and photoluminescence spectroscopy measurements. Single-crystal XRD analyses show that the reported compound crystallizes in the orthorhombic non-centrosymmetric space group Fdd2 and its crystal structure consists of anionic molecular Co-hexaborate units arranged into 3D-supramolecular honey-comb like structure network with the organic cation and water of crystallization occupying large tunnels voids along [110] through strong hydrogen bond interactions. In addition, Its electronic properties have also been investigated showing a considerable important gap energy well proving the semiconductor behavior and the photoluminescent property of reported material.

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Sugimoto, Kunihisa, Robert E. Dinnebier und Thomas Schlecht. „Crystal structure of dehydrated chlorartinite by X-ray powder diffraction“. Powder Diffraction 22, Nr. 1 (März 2007): 64–67. http://dx.doi.org/10.1154/1.2436546.

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In the course of an investigation of cracks in certain magnesia floors containing the mineral chlorartinite [Mg2(CO3)(H2O)(OH)]Cl·H2O, the dehydration process of chlorartinite was carried out in high vacuum. The crystal structure of dehydrated chlorartinite [Mg2(CO3)(H2O)(OH)]Cl was refined from laboratory X-ray powder diffraction data using the Rietveld method [R3c, a=22.6791(5) Å, c=7.22336(14) Å, V=3217.52(11) Å3, Z=18, Rp=4.13%, Rwp=5.82%]. Dehydrated chlorartinite exhibits the same type of 3D honeycomb zeolite-like crystal structure with large channels as the hydrated form. Compared to the hydrated form, the channels of dehydrated chlorartinite are empty because of the removal of all non-coordinating water molecules with the cell volume shrinking by 4.0%, leading to a more distorted environment of the magnesium atoms.

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Keszthelyi-Lándori, S. „NaI(Tl) camera crystals: imaging capabilities of hydrated regions on the crystal surface.“ Radiology 158, Nr. 3 (März 1986): 823–26. http://dx.doi.org/10.1148/radiology.158.3.3945758.

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Liu, Shijie, Suping Cui, Hongxia Guo, Yali Wang und Yan Zheng. „Adsorption of Lead Ion from Wastewater Using Non-Crystal Hydrated Calcium Silicate Gel“. Materials 14, Nr. 4 (10.02.2021): 842. http://dx.doi.org/10.3390/ma14040842.

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In order to obtain low-cost and excellent adsorption materials, this paper used calcium acetate and water glass as raw materials to synthesis hydrated calcium silicate gel by precipitation method. The performance and structure of hydrated calcium silicate gel were systematically studied by X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, specific surface area analyzer and scanning electron microscope. Studies have shown that, non-crystal hydrated calcium silicate gel (CSH) were successfully prepared, and the removal rate of lead ion using CSH reached more than 90%. The adsorption process is consistent with the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, and the limit adsorption capacity reaches 263.17 mg·g−1. The acid treatment experiment proved that the adsorption capacity of lead ion using CSH was satisfactory, and the adsorption rate remained at >60% after 5 cycles. The research may provide a low-cost, high-efficiency and high stability adsorbent.

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Ma, Tianqiong, Eugene A. Kapustin, Shawn X. Yin, Lin Liang, Zhengyang Zhou, Jing Niu, Li-Hua Li et al. „Single-crystal x-ray diffraction structures of covalent organic frameworks“. Science 361, Nr. 6397 (05.07.2018): 48–52. http://dx.doi.org/10.1126/science.aat7679.

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The crystallization problem is an outstanding challenge in the chemistry of porous covalent organic frameworks (COFs). Their structural characterization has been limited to modeling and solutions based on powder x-ray or electron diffraction data. Single crystals of COFs amenable to x-ray diffraction characterization have not been reported. Here, we developed a general procedure to grow large single crystals of three-dimensional imine-based COFs (COF-300, hydrated form of COF-300, COF-303, LZU-79, and LZU-111). The high quality of the crystals allowed collection of single-crystal x-ray diffraction data of up to 0.83-angstrom resolution, leading to unambiguous solution and precise anisotropic refinement. Characteristics such as degree of interpenetration, arrangement of water guests, the reversed imine connectivity, linker disorder, and uncommon topology were deciphered with atomic precision—aspects impossible to determine without single crystals.

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Burmester, Christoph, Kenneth C. Holmes und Rasmus R. Schröder. „Multiple isomorphous replacement for phase determination in protein crystals“. Proceedings, annual meeting, Electron Microscopy Society of America 53 (13.08.1995): 856–57. http://dx.doi.org/10.1017/s0424820100140658.

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Electron crystallography of 2D protein crystals can yield models with atomic resolution by taking Fourier amplitudes from electron diffraction and phase information from processed images. Imaging at atomic resolution is more difficult than the recording of corresponding high resolution electron diffraction patterns. Therefore attempts have been made to retrieve phase information from diffraction from heavy atom labelled protein crystals. The expected differences between native and labelled crystals are small, therefore a high experimental accuracy is necessary. This is achieved by the use of energy filter TEM and image plates, as dicussed in. Here we present electron diffraction data obtained from frozen hydrated 3D protein crystals with an energy filter microspcope and a specially designed image plate scanner. Data were recorded for the native crystal as well as for two different heavy atom derivatives. Differences between the native and the derivate forms can be detected and are significant.Electron diffraction patterns from frozen hydrated catalase crystals were recorded on an EFTEM Zeiss 912 Ω (120kV, zero loss mode, energy width ΔE=10eV, electron dose 5 e-/A2) using image plates and a quasi confocal scanner readout.

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Sala, Andrea, Zakiena Hoossen, Alessia Bacchi und Mino R. Caira. „Two Crystal Forms of a Hydrated 2:1 β-Cyclodextrin Fluconazole Complex: Single Crystal X-ray Structures, Dehydration Profiles, and Conditions for Their Individual Isolation“. Molecules 26, Nr. 15 (22.07.2021): 4427. http://dx.doi.org/10.3390/molecules26154427.

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Inclusion complexes between cyclodextrins (CDs) and active pharmaceutical ingredients (APIs) have potential for pharmaceutical formulation. Since crystallization of a given complex may result in the isolation of multiple crystal forms, it is essential to characterize these forms with respect to their structures and physicochemical properties to optimize pharmaceutical candidate selection. Here, we report the preparation and characterization of two crystallographically distinct hydrated forms of an inclusion complex between β-cyclodextrin (β-CD) and the antifungal API fluconazole (FLU) as well as temperature–concentration conditions required for their individual isolation. Determination of crystal water contents was achieved using thermoanalytical methods. X-ray analyses revealed distinct structural differences between the triclinic (TBCDFLU, space group P1) and monoclinic (MBCDFLU, space group C2) crystal forms. Removal of the crystals from their mother liquors led to rapid dehydration of the MBCDFLU crystal, while the TBCDFLU crystal was stable, a result that could be reconciled with the distinct packing arrangements in the respective crystals. This study highlights (a) the importance of identifying possible multiple forms of a cyclodextrin API complex and controlling the crystallization conditions, and (b) the need to characterize such crystal forms to determine the extent to which their physicochemical properties may differ.

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Mommertza, A., K. Dehnickea und J. Magull. „Die Kristallstruktur von [Na4(OSiPh3)4(H2O)3] / The Crystal Structure of [Na4(OSiPh3)4(H2O)3]“. Zeitschrift für Naturforschung B 51, Nr. 11 (01.11.1996): 1583–86. http://dx.doi.org/10.1515/znb-1996-1109.

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Colourless single crystals of the title compound are obtained from a saturated solution of NaOSiPh3 in toluene in a humid atmosphere. We have characterized [Na4(OSiPh3)H2O)3] by IR spectroscopy and by a crystal structure determination. Space group R3, Z = 6 , R = 0.056. Lattice dimensions at -70°C: a = b = 1540.3 pm, c = 2639.6 pm. The compound has the structure of a Na4O4 heterocubane which is only slighty distorted and in which one of the sodium atoms is not hydrated and shows coordination number three.

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Sani, Alessandra, Giovanna Vezzalini, Paolo Ciambelli und Maria Teresa Rapacciuolo. „Crystal structure of hydrated and partially NH4-exchanged heulandite“. Microporous and Mesoporous Materials 31, Nr. 3 (November 1999): 263–70. http://dx.doi.org/10.1016/s1387-1811(99)00077-3.

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Mazo, Mikhail A., Leonid I. Manevitch, Elena B. Gusarova, Alexander A. Berlin, Nikolay K. Balabaev und Gregory C. Rutledge. „Molecular Dynamics Simulation of Thermomechanical Properties of Montmorillonite Crystal. II. Hydrated Montmorillonite Crystal“. Journal of Physical Chemistry C 112, Nr. 44 (10.10.2008): 17056–62. http://dx.doi.org/10.1021/jp711188u.

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Schröder, Rasmus R., und Christoph Burmester. „Improvements in electron diffraction of frozen hydrated crystals by energy filtering and large-area single-electron detection“. Proceedings, annual meeting, Electron Microscopy Society of America 51 (01.08.1993): 666–67. http://dx.doi.org/10.1017/s0424820100149167.

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Diffraction patterns of 3D protein crystals embedded in vitrious ice are critical to record. Inelastically scattered electrons almost completely superimpose the diffraction pattern of crystals if the thickness of the crystal is higher than the mean free path of electrons in the specimen. Figure 1 shows such an example of an unfiltered electron diffraction pattern from a frozen hydrated 3D catalase crystal. However, for thin 2D crystals electron diffraction has been the state of the art method to determine the Fourier amplitudes for reconstructions to atomic level, and in one case the possibility of obtaining Fourier phases from diffraction patterns has been studied. One of the main problems could be the background in the diffraction pattern due to inelastic scattering and the recording characteristics for electrons of conventional negative material.It was pointed out before, that the use of an energy filtered TEM (EFTEM) and of the Image Plate as a large area electron detector gives considerable improvement for detection of diffraction patterns.

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Torrelles, Xavier, Immad M. Nadeem, Anna Kupka, Adrián Crespo-Villanueva, Sandrina Meis, Hermann Gies und Oier Bikondoa. „Pristine and hydrated fluoroapatite (0001)“. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, Nr. 5 (10.09.2019): 830–38. http://dx.doi.org/10.1107/s2052520619010412.

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The surface structure of fluoroapatite (0001) (FAp0001) under quasi-dry and humid conditions has been probed with surface X-ray diffraction (SXRD). Lateral and perpendicular atomic relaxations corresponding to the FAp0001 termination before and after H2O exposure and the location of the adsorbed water molecules have been determined from experimental analysis of the crystal truncation rod (CTR) intensities. The surface under dry conditions exhibits a bulk termination with relaxations in the outermost atomic layers. The hydrated surface is formed by a disordered partially occupied H2O layer containing one water molecule (33% surface coverage) adsorbed at each of the three surface Ca atoms, and is coupled with one OH group randomly bonded to each of the three topmost P atoms with a 33% surface coverage.

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Shi, Haishan, Fupo He und Jiandong Ye. „Synthesis and structure of iron- and strontium-substituted octacalcium phosphate: effects of ionic charge and radius“. Journal of Materials Chemistry B 4, Nr. 9 (2016): 1712–19. http://dx.doi.org/10.1039/c5tb02247a.

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Glasser, Leslie. „The effective volumes of waters of crystallization: non-ionic pharmaceutical systems“. Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, Nr. 5 (31.08.2019): 784–87. http://dx.doi.org/10.1107/s2052520619010436.

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The physical properties of organic solids are altered when hydrated (and, more generally, when solvated) and this is of particular significance for pharmaceuticals in application; for instance, the solubility of a hydrate is less than that of its parent. The effective volumes of waters of crystallization for non-ionic pharmaceuticals (where the `effective' volume is the difference per water molecule between the hydrate volume and the volume of the anhydrous parent) are here examined. This investigation contrasts with our earlier study of effective volumes of waters of crystallization for ionic materials where the coulombic forces are paramount. Volumetric properties are significant since they correlate strongly with many thermodynamic properties. Twenty-nine hydrate/parent systems have been identified, and their volumetric properties are reported and analysed (apart from aspartame and ephedrine for which the structural data are inconsistent). Among these systems, the data for paracetamol are extensive and it is possible to differentiate among the volumetric properties of its three polymorphs and to quantify the effect of temperature on their volumes. The effective volumes in both ionic and non-ionic systems are similar, with a median effective volume of 22.8 Å3 for the non-ionic systems compared with 24.2 Å3 for the ionic systems, and both are smaller than the molecular volume of 30 Å3 of ambient liquid water – which appears to be an upper limit to the effective volumes of waters of crystallization under ambient conditions. These results will be supportive in checking and confirmation of hydrated crystal structures and in assessing their thermodynamic properties.

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Rodríguez-Macías, Fernando J., José E. Ortiz-Castillo, Erika López-Lara, Alejandro J. García-Cuéllar, José L. López-Salinas, César A. García-Pérez, Orlando Castilleja-Escobedo und Yadira I. Vega-Cantú. „Syntheses of Nanostructured Magnesium Carbonate Powders with Mesoporous Structures from Carbon Dioxide“. Applied Sciences 11, Nr. 3 (26.01.2021): 1141. http://dx.doi.org/10.3390/app11031141.

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In this work, we present the results of two synthesis approaches for mesoporous magnesium carbonates, that result in mineralization of carbon dioxide, producing carbonate materials without the use of cosolvents, which makes them more environmentally friendly. In one of our synthesis methods, we found that we could obtain nonequilibrium crystal structures, with acicular crystals branching bidirectionally from a denser core. Both Raman spectroscopy and X-ray diffraction showed these crystals to be a mixture of sulfate and hydrated carbonates. We attribute the nonequilibrium morphology to coprecipitation of two salts and short synthesis time (25 min). Other aqueous synthesis conditions produced mixtures of carbonates with different morphologies, which changed depending on drying temperature (40 or 100 °C). In addition to aqueous solution, we used supercritical carbon dioxide for synthesis, producing a hydrated magnesium carbonate, with a nesquehonite structure, according to X-ray diffraction. This second material has smaller pores (1.01 nm) and high surface area. Due to their high surface area, these materials could be used for adsorbents and capillary transport, in addition to their potential use for carbon capture and sequestration.

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Yakubovich, Olga, Ian Steele und Oxana Karimova. „Crystal structure interconnections in a family of hydrated phosphate-sulfates“. Acta Crystallographica Section A Foundations and Advances 70, a1 (05.08.2014): C1091. http://dx.doi.org/10.1107/s2053273314089086.

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The phosphate-sulfate family incorporates several water-containing hypergene minerals with various structures. We determined the crystal structure of lately discovered [1] fibrous mineral arangasite, [Al2F(H2O)6(PO4)(SO4)]·3(H2O) using single-crystal synchrotron diffraction at 100 K (a =7.073(1), b=9.634(2), c=10.827(2) Å, β=79.60(1)0, P2/a, Z=2). Its crystal chemical interpretation has allowed us to reveal some interesting features in a title group of compounds. The arangasite crystal structure is dominated by chains extending in the [100] direction and built of pairs of corner-shared Al octahedra joined through bridging F atoms and P tetrahedra. They alternate in the [001] with S tetrahedra forming layers parallel to the ac plane through a system of hydrogen bonds. Along [010] the complex layers are separated by layers of H2O molecules. Hydrogen bonding serves here as the only mechanism providing linkage between the main structural fragments. The Al/ P chains are topologically identical to the chains built from Fe octahedra and P tetrahedra in the triclinic structure of destinezite, Fe2(OH)(PO4)(SO4)(H2O)6[2]. The repeating subunit of both chains consists of two octahedra and one tetrahedron sharing vertices. A main difference among the chains arises from their chemistry; Al octahedra in arangasite form pairs by sharing the F vertex of neighboring polyhedra, whereas pairs of Fe octahedra in destinezite are linked together through the oxygen vertex of an OH group. As a result, the larger size of the Fe octahedra compared to Al octahedra causes a larger c = 7.31 Å along the chain in destinezite. Additional SO4tetrahedra here are attached to these chains along their periphery through an oxygen vertex bridge with Fe octahedra. The monoclinic sanjuanite, Al2(PO4)(SO4)(OH)(H2O)9structure [3] is composed of Al/P chains, parallel to a = 6.11 Å. These chains are also built from three-member units that include corner-sharing pairs of octahedra connected by PO4tetrahedron, but they are not topologically equivalent to the chains in the arangasite and destinezite structures. Similar to arangasite, sulfate groups and H2O molecules reside between chains in the sanjuanite structure with hydrogen bonding. Thus, similar the crystal chemical formulae of sanjuanite and arangasite differ with respect to the (OH) → F substitution, which results in contrasting unit cell parameters. Note, that the unit cell volume of sanjuanite, is twice as large as arangasite.

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