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Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials

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https://www.readbyqxmd.com/read/29616997/crystal-structures-of-alkali-metal-group-1-citrate-salts
#1
Alagappa Rammohan, James A Kaduk
The crystal structures of 16 new alkali metal citrates were determined using powder and/or single crystal techniques. These structures and 12 previously determined citrate structures were optimized using density functional techniques. The central portion of a citrate ion is fairly rigid, while the conformations of the terminal carboxylate groups exhibit no preferences. The citrate-metal bonding is ionic. Trends in metal-citrate coordination are noted. The energy of an O-H...O hydrogen bond is proportional to the square root of the H...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616996/crystal-structure-phase-transition-and-structural-deformations-in-iron-borate-y-0-95-bi-0-05-fe-3-bo-3-4-in-the-temperature-range-90-500-k
#2
Ekaterina S Smirnova, Olga A Alekseeva, Alexander P Dudka, Vladimir V Artemov, Yan V Zubavichus, Irina A Gudim, Leonard N Bezmaterhykh, Kirill V Frolov, Igor S Lyubutin
An accurate X-ray diffraction study of (Y0.95 Bi0.05 )Fe3 (BO3 )4 single crystals in the temperature range 90-500 K was performed on a laboratory diffractometer and used synchrotron radiation. It was established that the crystal undergoes a diffuse structural phase transition in the temperature range 350-380 K. The complexity of localization of such a transition over temperature was overcome by means of special analysis of systematic extinction reflections by symmetry. The transition temperature can be considered to be Tstr ≃ 370 K...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616995/phase-transitions-in-ferroelectric-4-aminopyridinium-tetrachloroantimonate-iii-revisited
#3
Anna Gągor
New X-ray diffraction studies on the crystal structure of ferroelectric [4-NH2 C5 H4 NH][SbCl4 ] indicate that in the broad temperature range from 240 to 304 K covering the three intermediate phases, the crystal structure is modulated. Phase II is incommensurately modulated with modulation vector q = βb*, β varying from 0.60 to 0.66 and monoclinic C2/c(0β0)s0 superspace group. Ferroelectric phase III is commensurate with q = 2\over 3b* and Cc(0β0)0 symmetry. Polar phase IV is incommensurately modulated with β varying from 0...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616994/accurate-and-precise-lattice-parameters-of-h-2-o-and-d-2-o-ice-ih-between-1-6-and-270-k-from-high-resolution-time-of-flight-neutron-powder-diffraction-data
#4
A Dominic Fortes
Accurate and precise lattice parameters for D2 O and H2 O varieties of hexagonal ice (ice Ih, space group P63 /mmc) have been obtained in the range 1.6 to 270 K. Precision of the lattice parameters (∼0.0002% in a and 0.0004% in c for D2 O, 0.0008% in a and 0.0015% in c for H2 O) is ensured by use of the time-of-flight method on one of the longest primary neutron flight-path instruments in the world, the High-Resolution Powder Diffractometer at the ISIS neutron source. These data provide a more precise description of the negative thermal expansion of the material at low temperatures than the previous synchrotron `gold standard' [Röttger et al...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616993/hydrocerussite-related-minerals-and-materials-structural-principles-chemical-variations-and-infrared-spectroscopy
#5
Oleg Siidra, Diana Nekrasova, Wulf Depmeier, Nikita Chukanov, Anatoly Zaitsev, Rick Turner
White lead or basic lead carbonate, 2PbCO3 ·Pb(OH)2 , the synthetic analogue of hydrocerussite Pb3 (OH)2 (CO3 )2 , has been known since antiquity as the most frequently used white paint. A number of different minerals and synthetic materials compositionally and structurally related to hydrocerussite have been described within the last two decades. Herein, a review is given of general structural principles, chemical variations and IR spectra of the rapidly growing family of hydrocerussite-related minerals and synthetic materials...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616992/ionic-network-analysis-of-tectosilicates-the-example-of-coesite-at-variable-pressure
#6
Melina Reifenberg, Noel W Thomas
The method of ionic network analysis [Thomas (2017). Acta Cryst. B73, 74-86] is extended to tectosilicates through the example of coesite, the high-pressure polymorph of SiO2 . The structural refinements of Černok et al. [Z. Kristallogr. (2014), 229, 761-773] are taken as the starting point for applying the method. Its purpose is to predict the unit-cell parameters and atomic coordinates at (p-T-X) values in-between those of diffraction experiments. The essential development step for tectosilicates is to define a pseudocubic parameterization of the O4 cages of the SiO4 tetrahedra...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616991/revisiting-the-i-overline-bf-1-structures-of-high-temperature-ca-rich-plagioclase-feldspar-a-single-crystal-neutron-and-x-ray-diffraction-study
#7
Shiyun Jin, Xiaoping Wang, Huifang Xu
The I{\overline 1} structures of four natural Ca-rich plagioclase feldspars formed at high temperature were analysed using single-crystal neutron and X-ray diffraction. The neutron time-of-flight Laue diffractometer at the ORNL Spallation Neutron Source (Tennessee, USA) combined with a single-crystal X-ray diffraction instrument were able to reveal some new details about these already intensively studied structures. The split oxygen atoms refined from the neutron diffraction data show the underlying mechanism of Ca-Na ordering and the anisotropic P{\overline 1} ordering along the c-axis...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616990/aromaticity-of-benzene-derivatives-an-exploration-of-the-cambridge-structural-database
#8
Irena Majerz, Teresa Dziembowska
The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups in ortho, meta and para positions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616989/a-method-for-visualization-of-the-variation-of-noncovalent-interactions-in-crystal-structures-of-conformational-polymorphs
#9
Anton V Savchenkov, Viktor N Serezhkin
A method for clear visualization of the variation of noncovalent interactions in crystal structures of conformational polymorphs is developed and introduced. The first stage of the method establishes the characteristics of all, without exception, noncovalent interactions in all crystal structures under discussion. This is possible using a strict and objective method of construction of Voronoi-Dirichlet polyhedra within the framework of the stereoatomic model of crystal structures. The second stage of the method then involves plotting of diagrams, showing the relation between parameters characterizing interatomic interactions and chosen geometric parameters of molecules...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616988/crystal-growth-structure-and-characterization-of-er-6-b-4-o-15-as-self-activated-eye-safe-laser-material-within-the-near-infrared-waveband
#10
Yan Wang, Wei Zhang, Ziyi Li, Jianfu Li, Zhaojie Zhu, Zhenyu You, Chaoyang Tu
A new rare-earth borate Er6 B4 O15 was synthesized by a solid-state reaction technique. The crystal was obtained by a flux method. Single-crystal X-ray diffraction analysis revealed that the crystal structure is composed of ErO6 polyhedra sharing edges and BO3 groups. The absorption, near-infrared fluorescence spectra and the fluorescence decay curve of Er:4 I13/2 energy level in the Er6 B4 O15 crystal were measured at room temperature. The absorption peak was located at 977 nm with absorption cross section of 1...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29616987/the-crystal-structure-of-fe-2-pimic6-anthco-2-ch-3-cn-%C3%A2-fe-2-pimic6-anthco-2-ch-3-cn-0-9-ch-2-cl-2-0-1-%C3%A2-fe-2-pimic6-anthco-2-oh-2-%C3%A2-0-75ch-3-cn-a-crystallographer-s-nightmare-or-a-fascinating-case-of-disorder
#11
Sabine Becker
Refinement of large crystal structures as well as that of disordered structures can be challenging. If both features come together, structure refinement has the potential of becoming a crystallographer's nightmare. Here, the refinement of the large and highly disordered structure of [Fe2 (PIMIC6)(AnthCO2 )(CH3 CN)]·[Fe2 (PIMIC6)(AnthCO2 )(CH3 CN)0.9 (CH2 Cl2 )0.1 ]·[Fe2 (PIMIC6)(AnthCO2 )(OH2 )]·0.75CH3 CN [(1), PIMIC6 is a phenol-imine-based macrocycle, AnthCO2 is an anthracene acid anion] is described and discussed...
April 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981007/first-line-antituberculosis-drug-pyrazinamide-its-pharmaceutically-relevant-cocrystals-and-a-salt
#12
Kashyap Kumar Sarmah, Trishna Rajbongshi, Sourav Bhowmick, Ranjit Thakuria
A few pyrazinamide (Pyz) cocrystals involving hydroxybenzoic/cinnamic acid derivatives [2,4-dihydroxybenzoic acid (24DHBA); 2,6-dihydroxybenzoic acid (26DHBA); 3,5-dihydroxybenzoic acid (35DHBA) and nutraceutical molecule ferulic acid (FRA)] and the first example of a molecular salt with p-toluenesulfonic acid (pTSA) have been prepared and characterized using various solid-state techniques. A high-temperature cocrystal polymorph of Pyz·FRA has been characterized from the endothermic peaks observed using differential scanning calorimetry...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981006/investigations-of-the-phase-relations-among-e1-e2-and-c-bar-bf-1-structures-of-na-rich-plagioclase-feldspars-a-single-crystal-x-ray-diffraction-study
#13
Shiyun Jin, Huifang Xu
The subsolidus phase relations of plagioclase feldspar solid solution have been puzzling mineralogists and petrologists for decades, mainly due to the complicated structures of intermediate plagioclase at low temperature. The crystal structures of 12 Na-rich plagioclase samples are investigated by single-crystal X-ray diffraction analyses. The samples studied cover a compositional range from An21 to An49 (An is anorthite, CaAl2 Si2 O8 ), as well as a wide variety of origins, from extremely slow-cooled gabbroic rocks to pegmatite and metamorphic rocks...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981005/3-pyridin-4-yl-acetylacetone-a-donor-ligand-towards-mercury-ii-halides-and-a-versatile-linker-for-complex-materials
#14
Khai Nghi Truong, Carina Merkens, Ulli Englert
The ditopic organic molecule 3-(pyridin-4-yl)acetylacetone (HacacPy) acts as a pyridine-type ligand towards HgX2 (X = Cl, Br, I). The nature of the anion and the ligand-to-cation ratio dominate the outcome of the reaction. Two different coordination compounds form with HgCl2 , namely a ligand-rich mononuclear complex, HgCl2 (HacacPy)2 , and a ligand-deficient one-dimensional chain polymer, [Hg(μ-Cl)2 (HacacPy)]1 ∞ , with five-coordinated HgII cations. Two compounds are also observed for HgBr2 , a molecular complex isomorphous to the chloride derivative and a chain polymer with the composition [Hg(μ-Br)Br(HacacPy)]1 ∞ , in which the cations are four-coordinated...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981004/non-covalent-interactions-in-the-multicomponent-crystal-of-1-aminocyclopentane-carboxylic-acid-oxalic-acid-and-water-a-crystallographic-and-a-theoretical-approach
#15
Asiloé J Mora, Lusbely M Belandria, Gerzon E Delgado, Luis E Seijas, Angel Lunar, Rafael Almeida
Single-crystal X-ray diffraction and quantum mechanical theories were used to examine in detail the subtle nature of non-covalent interactions in the [2:1:1] multicomponent crystal of 1,1-aminocyclopentanecarboxylic acid:oxalic acid:water. The crystal, which is a hydrate salt of the amino acid with the hydrogen-oxalate ion, also contains the zwitterion of the amino acid in equal proportions. It was found that a dimeric cation [Acc5(Z)...Acc5(C)]+ bonded by an O-H...O hydrogen bond exists due to a charge transfer between acid and carboxylate groups...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981003/predicting-displacements-of-octahedral-cations-in-ferroelectric-perovskites-using-machine-learning
#16
Prasanna V Balachandran, Toby Shearman, James Theiler, Turab Lookman
In ferroelectric perovskites, displacements of cations from the high-symmetry lattice positions in the paraelectric phase break the spatial inversion symmetry. Furthermore, the relative magnitude of ionic displacements correlate strongly with ferroelectric properties such as the Curie temperature. As a result, there is interest in predicting the relative displacements of cations prior to experiments. Here, machine learning is used to predict the average displacement of octahedral cations from its high-symmetry position in ferroelectric perovskites...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981002/empirical-lewis-acid-strengths-for-135-cations-bonded-to-oxygen
#17
Olivier Charles Gagné, Frank Christopher Hawthorne
New and updated Lewis acid strengths are listed for 135 cations bonded to oxygen for use with published Lewis base strengths. A strong correlation between Lewis acid strength and ionization energy is shown, and correlation with electronegativity is confirmed.
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981001/multidimensional-structural-variation-in-the-cyanotrichite-family-of-merotypes-camerolaite-3b-f-bar-1
#18
Stuart J Mills, Andrew G Christy, Georges Favreau, Valérie Galea-Clolus
A new superstructure of the mineral camerolaite, Cu6 Al3 (OH)18 (H2 O)2 [Sb(OH)6 ](SO4 ), has been refined in space group P\bar 1 with unit-cell parameters aP = 7.7660 (16), bP = 8.759 (4), cP = 11.306 (2) Å, αP = 108.67 (4), βP = 83.41 (3), γP = 126.64 (2)°, V = 581.6 (3) Å3 and Z = 1, with R1 = 0.0951 (all data). This is the first refined example of a cyanotrichite-group mineral in which long-range order of interlayer anions produces a superstructure along b, although diffuse scattering has previously been reported that corresponds to short-range order...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28981000/non-order-disorder-allotwinning-of-the-rhenium-pincer-complex-cis-re-pnp-ch-2-ipr-co-2-cl
#19
Mathias Glatz, Berthold Stöger, Karl Kirchner
Crystals of cis-Re[(PNPCH2 -iPr)(CO)2 Cl] (1) are made up of two geometrically non-equivalent polytypes with respective symmetries of P21 /c and I2/a. The structures were determined in a concurrent refinement, taking into account overlap of diffraction spots. The polytypes are composed of layers with px 121 /c1 symmetry and are of the non-order-disorder (OD) type (the layer interfaces are non-equivalent). Whereas the molecules of (1) differ in both polytypes, the Re atoms are located at nearly identical positions...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28980999/the-structure-directing-amine-changes-everything-structures-and-optical-properties-of-two-dimensional-thiostannates
#20
Mette Ø Filsø, Iman Chaaban, Amer Al Shehabi, Jørgen Skibsted, Nina Lock
Two different two-dimensional thiostannates (SnS) were synthesized using tris(2-aminoethyl)amine (tren) or 1-(2-aminoethyl)piperidine (1AEP) as structure-directing agents. Both structures consist of negatively charged thiostannate layers with charge stabilizing cations sandwiched in-between. The fundamental building units are Sn3 S4 broken-cube clusters connected by double sulfur bridges to form polymeric (Sn3 S7 2- )n honeycomb hexagonal layers. The compounds are members of the R-SnS-1 family of structures, where R indicates the type of cation...
October 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
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