journal
MENU ▼
Read by QxMD icon Read
search

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

journal
https://www.readbyqxmd.com/read/28572560/chiral-and-achiral-crystals-charge-assisted-hydrogen-bond-patterns-and-self-organization-of-selected-solid-diaminium-thiosulfates
#1
Agnieszka Brozdowska, Jarosław Chojnacki
A series of diaminium thiosulfates, derivatives of diamines: NH2CH2CH(CH3)NH2 (1) and NH2(CH2)nNH2, n = 3-6 [(2)-(5)] and thiosulfuric acid were prepared and their structures determined by single-crystal X-ray diffraction analysis. Compounds (1), (2) and (4) turned out to be hydrates. The crystal structure of 1,2-propylenediaminium thiosulfate is chiral and exhibits spontaneous resolution. Crystals for both enantiomers [(1a) and (1b)] were obtained with high enantiometric excess and examined. An extended network of strong, charge-assisted hydrogen bonding of the (+)N-H...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572559/crystallographic-and-optical-study-of-linb1%C3%A2-%C3%A2-xtaxo3
#2
S Huband, D S Keeble, N Zhang, A M Glazer, A Bartasyte, P A Thomas
Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572558/synthesis-and-crystal-structure-of-pyrroloquinoline-quinol-pqqh2-and-pyrroloquinoline-quinone-pqq
#3
Kazuto Ikemoto, Shigeki Mori, Kazuo Mukai
Pyrroloquinoline quinone (PQQ) is a water-soluble quinone compound first identified as a cofactor of alcohol- and glucose-dehydrogenases (ADH and GDH) in bacteria. For example, in the process of ADH reaction, alcohol is oxidized to the corresponding aldehyde, and inversely PQQ is reduced to pyrroloquinoline quinol (PQQH2). PQQ and PQQH2 molecules play an important role as a cofactor in ADH and GDH reactions. However, crystal structure analysis has not been performed for PQQ and PQQH2. In the present study, the synthesis of PQQH2 powder crystals was performed under air, by utilizing vitamin C as a reducing agent...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572557/the-hydrogen-bond-between-n-h-or-o-h-and-organic-fluorine-favourable-yes-competitive-no
#4
Robin Taylor
A study was made of X-H...F-C interactions (X = N or O) in small-molecule crystal structures. It was primarily based on 6728 structures containing X-H and C-F and no atom heavier than chlorine. Of the 28 451 C-F moieties in these structures, 1051 interact with X-H groups. However, over three-quarters of these interactions are either the weaker components of bifurcated hydrogen bonds (so likely to be incidental contacts) or occur in structures where there is a clear insufficiency of good hydrogen-bond acceptors such as oxygen, nitrogen or halide...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572556/sr1-2ce5-14%C3%A2-1-7wo4-a-new-modulated-ternary-scheelite-compound
#5
Rafael Hernandez Damascena Dos Passos, Madjid Arab, Carlson Pereira de Souza, Christine Leroux
For the first time, a ternary tetragonal scheelite structure tungstate with strontium and cerium cations, (Sr,Ce)WO4, was synthesized. As much as 35% Ce could be inserted into the structure, leaving 1\over 7 of the (Sr,Ce) cation sites vacant. Partial ordering of Sr and Ce, with atomic displacements, were shown by high-resolution electron microscopy. Two-dimensional incommensurate modulations occur in this material, in small domains 20 nm in size. The band gap of this compound is significantly lower than the band gap of SrWO4 and this was related to the distortions of WO4 and (Sr,Ce)O8 polyhedra...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572555/searching-for-stereoisomerism-in-crystallographic-databases-algorithm-analysis-and-chiral-curiosities
#6
E Grothe, H Meekes, R de Gelder
The automated identification of chiral centres in molecular residues is a non-trivial task. Current tools that allow the user to analyze crystallographic data entries do not identify chiral centres in some of the more complex ring structures, or lack the possibility to determine and compare the chirality of multiple structures. This article presents an approach to identify asymmetric C atoms, which is based on the atomic walk count algorithm presented by Rücker & Rücker [(1993), J. Chem. Inf. Comput. Sci...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572554/-die-symmetrie-von-spiralketten
#7
Ulrich Müller
In crystals, polymeric chain molecules often adopt helical structures. Neglecting small distortions possibly caused by an anisotropic environment within the crystal, the symmetry of the single helix can be described by a rod group, which has translational symmetry in one dimension. The rod groups have Hermann-Mauguin symbols similar to space groups, beginning with a script style \scr p followed by a screw-axis symbol; the order of the screw axis can adopt any value. In a crystal, the rod-site symmetry, the so-called penetration rod group, must be a common crystallographic rod subgroup of the molecular rod group and the space group...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572553/formation-and-distortion-of-iodidoantimonates-iii-the-first-isolated-sbi6-3-octahedron
#8
Maciej Bujak
The ability to intentionally construct, through different types of interactions, inorganic-organic hybrid materials with desired properties is the main goal of inorganic crystal engineering. The primary deformation, related to intrinsic interactions within inorganic substructure, and the secondary deformation, mainly caused by the hydrogen bond interactions, are both responsible for polyhedral distortions of halogenidoantimonates(III) with organic cations. The evolution of structural parameters, in particular the Sb-I secondary- and O/N/C-H...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572552/structural-and-raman-spectroscopic-characterization-of-pyroxene-type-compounds-in-the-cacu1-xznxge2o6-solid-solution-series
#9
Günther J Redhammer, Gerold Tippelt, Andreas Reyer, Reinhard Gratzl, Andreas Hiederer
Pyroxene-type germanate compounds with the composition CaCuGe2O6-CaZnGe2O6 have been synthesized via a solid-state ceramic sintering route. Phase-pure polycrystalline and small single-crystal material was obtained all over the series, representing a complete solid-solution series. Differential thermal analysis, single-crystal X-ray diffraction and Raman spectroscopy were used to characterize phase stability, phase changes and structural alterations induced by the substitution of Cu(2+) with Zn(2+). Whereas pure CaCuGe2O6 exhibits P21/c symmetry with a strong distortion of the M1 octahedra and two different Ge sites, one of them with an unusual fivefold coordination, the replacement of Cu(2+) by Zn(2+) induces a chemically driven phase change to the C2/c symmetry...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572551/an-ordering-phase-transition-short-hydrogen-bonds-and-high-z-in-the-structure-of-ni-hpydc-2%C3%A2-3h2o
#10
Zohreh Derikvand, Xian B Powers, Marilyn M Olmstead
The structure of Ni(Hpydc)2·3H2O (H2pydc = pyridine-2,6-dicarboxylic acid, also known as dipicolinic acid) has been reinvestigated at variable temperatures. At room temperature, it matches the known structure in the space group P21/c, but at 180 K it undergoes a phase transformation to a twinned structure in Cc. By 120 K, the structure is ordered and twinned with Z' = 4, and shows interesting short hydrogen-bonding interactions that include the formation of hydroxonium species.
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572550/synthesis-crystallization-x-ray-structural-characterization-and-solid-state-assembly-of-a-cyclic-hexapeptoid-with-propargyl-and-methoxyethyl-side-chains
#11
Consiglia Tedesco, Eleonora Macedi, Alessandra Meli, Giovanni Pierri, Giorgio Della Sala, Christina Drathen, Andrew N Fitch, Gavin B M Vaughan, Irene Izzo, Francesco De Riccardis
The synthesis and the structural characterization of a cyclic hexapeptoid with four methoxyethyl and two propargyl side chains have disclosed the presence of a hydrate crystal form [form (I)] and an anhydrous crystal form [form (II)]. The relative amounts of form (I) and form (II) in the as-purified product were determined by Rietveld refinement and depend on the purification procedures. In crystal form (I), peptoid molecules assemble in a columnar arrangement by means of side-chain-to-backbone C=CH...OC hydrogen bonds...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572549/the-impact-of-anion-ordering-on-octahedra-distortion-and-phase-transitions-in-srtao2n-and-batao2n
#12
Chun Hai Wang, Brendan J Kennedy, André L Menezes de Oliveira, Julia Polt, Kevin Steven Knight
In this work we synthesized BaTaO2N and SrTaO2N using a two-step high-temperature solid-state reaction method and analysed the structural distortions, relative to the ideal cubic perovskite structure, according to group theory. From a complete distortion analysis/refinement using high-resolution neutron diffraction data in the temperature range 8 to 613 K, we identified tetragonal structures for BaTaO2N [P4/mmm (No. 123)] and SrTaO2N [I4/mcm (No. 140)]. In contrast to an anion-disordered cubic perovskite (Pm \overline{3}m No...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572548/ordered-vacancy-distribution-in-2-1-mullite-a-superspace-model
#13
Paul B Klar, Noelia de la Pinta, Gabriel A Lopez, Iñigo Etxebarria, Tomasz Breczewski, Gotzon Madariaga
A mullite single crystal with composition Al4.84Si1.16O9.58 (2) exhibiting sharp satellite reflections was investigated by means of X-ray diffraction. For the refinement of a superspace model in the superspace group Pbam(α0½)0ss different scale factors for main and satellite reflections were used in order to describe an ordered mullite structure embedded in a disordered polymorph. The ordered fraction of the mullite sample exhibits a completely ordered vacancy distribution and can be described as a block structure of vacancy blocks (VBs) that alternate with vacancy-free blocks (VFBs) along a and c...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572547/could-incommensurability-in-sulfosalts-be-more-common-than-thought-the-case-of-meneghinite-cupb13sb7s24
#14
Luca Bindi, Václav Petříček, Cristian Biagioni, Jakub Plášil, Yves Moëlo
The structure of meneghinite (CuPb13Sb7S24), from the Bottino mine in the Apuan Alps (Italy), has been solved and refined as an incommensurate structure in four-dimensional superspace. The structure is orthorhombic, superspace group Pnma(0β0)00s, cell parameters a = 24.0549 (3), b = 4.1291 (6), c = 11.3361 (16) Å, modulation vector q = 0.5433 (4)b*. The structure was refined from 6604 reflections to a final R = 0.0479. The model includes modulation of both atomic positions and displacement parameters, as well as occupational waves...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572546/identification-of-a-deleterious-phase-in-photocatalyst-based-on-cd1%C3%A2-%C3%A2-xznxs-zn-oh-2-by-simulated-xrd-patterns
#15
Svetlana Cherepanova, Dina Markovskaya, Ekaterina Kozlova
The X-ray diffraction (XRD) pattern of a deleterious phase in the photocatalyst based on Cd1 - xZnxS/Zn(OH)2 contains two relatively intense asymmetric peaks with d-spacings of 2.72 and 1.56 Å. Very small diffraction peaks with interplanar distances of (d) ≃ 8.01, 5.40, 4.09, 3.15, 2.49 and 1.35 Å are characteristic of this phase but not always observed. To identify this phase, the XRD patterns for sheet-like hydroxide β-Zn(OH)2 and sheet-like hydrozincite Zn5(CO3)2(OH)6 as well as for turbostratic hydrozincite were simulated...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572545/growth-crystal-structure-hirshfeld-surface-optical-piezoelectric-dielectric-and-mechanical-properties-of-bis-l-asparaginium-hydrogensquarate-single-crystal
#16
Harsh Yadav, Nidhi Sinha, Sahil Goel, Budhendra Singh, Igor Bdikin, Anupama Saini, Kovuru Gopalaiah, Binay Kumar
Molecular organic single crystals of bis(L-asparaginium hydrogensquarate) monohydrate [BASQ; (C8H10N2O7)2·H2O] have been grown by solution technique. Crystallographic information was investigated by single-crystal X-ray diffraction (SCXRD) analysis. Hirshfeld surface and fingerprint plot studies were performed to understand the intermolecular interactions of the BASQ crystal in graphical representation. Functional group identification was studied with FT-IR (Fourier transform-IR) spectroscopy. The positions of proton and carbon atoms in the BASQ compound were analyzed using NMR spectroscopy...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572544/temperature-induced-reversible-structural-phase-transition-and-x-ray-diffuse-scattering-in-2-amino-3-nitropyridinium-hydrogen-sulfate
#17
Tamara J Bednarchuk, Dorota Kowalska, Vasyl Kinzhybalo, Marek Wołcyrz
The novel polar material 2-amino-3-nitropyridinium hydrogen sulfate, C5H6N3O2(HSO4) (abbreviated as 2A3NP-HS), was obtained and structurally characterized by means of single-crystal X-ray diffraction. At room temperature, 2A3NP-HS crystallizes as a non-centrosymmetric disordered phase (I) in the orthorhombic Pna21 space group. On cooling below 298 K, 2A3NP-HS undergoes a reversible phase transition to phase (II) with the monoclinic non-centrosymmetric P21 space group. This transition might be classified as an `order-disorder' type...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572543/the-future-of-topological-analysis-in-experimental-charge-density-research
#18
Piero Macchi
In a recent paper, Dittrich (2017) critically discussed the benefits of analysing experimental electron density within the framework of the quantum theory of atoms in molecules, often called simply the topological analysis of the charge density. The point he raised is important because it challenges the scientific production of a very active community. The question whether this kind of investigation is still sensible is intriguing and it fosters a multifaceted answer. Granted that none can predict the future of any field of science, but an alternative point of view emerges after answering three questions: Why should we investigate the electron charge (and spin) density? Is the interpretative scheme proposed by the quantum theory of atoms in molecules useful? Is an experimental charge density necessary?...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28572542/is-there-a-future-for-topological-analysis-in-experimental-charge-density-research
#19
Birger Dittrich
Topological analysis using Bader and co-worker's Atoms in Molecules theory has seen many applications in theoretical chemistry and experimental charge-density research. A brief overview of successful early developments, establishing topological analysis as a research tool for characterizing intramolecular chemical bonding, is provided. A lack of vision in many `descriptive but not predictive' subsequent studies is discussed. Limitations of topology for providing accurate energetic estimates of intermolecular interaction energies are put into perspective...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28362296/triclinic-crystal-structure-distortion-of-multiferroic-bimn7o12
#20
Wojciech A Sławiński, Hiroshi Okamoto, Helmer Fjellvåg
The quadruple perovskite BiMn7O12 obtained via high-pressure synthesis was investigated by high-resolution synchrotron X-ray powder diffraction over a temperature range of 10 to 295 K. Careful Rietveld analysis reveals triclinic lattice distortion of BiMn7O12 at 295 K, which increases upon cooling to 10 K. Also hkl-dependent anisotropic Bragg reflection shape was introduced to give a precise description of the diffracted intensities. Importantly BiMn7O12 crystal structure was described in the non-centrosymmetric I1 triclinic space group...
April 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
journal
journal
47671
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"