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

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https://www.readbyqxmd.com/read/30297552/melting-point-molecular-symmetry-and-aggregation-of-tetrachlorobenzene-isomers-the-role-of-halogen-bonding
#1
Maciej Bujak
Tetrachlorobenzenes represent one of the best known, but not yet fully understood, group of isomers of the structure-melting point relationship. The differences in melting temperatures of these structurally related compounds were rationalized in terms of the hierarchy and nature of formed noncovalent interactions, and the molecular aggregation that is influenced by molecular symmetry. The highest melting point is associated with the highly symmetric 1,2,4,5-tetrachlorobenzene isomer. The structures of less symmetrical 1,2,3,4-tetrachlorobenzene and 1,2,3,5-tetrachlorobenzene, determined at 270 and 90 K, show a distinct pattern of halogen bonds, characterized by the different numbers and types of interactions...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297551/crystal-packing-control-of-a-trifluoromethyl-substituted-furan-phenylene-co-oligomer
#2
Alina A Sonina, Igor P Koskin, Peter S Sherin, Tatyana V Rybalova, Inna K Shundrina, Evgeny A Mostovich, Maxim S Kazantsev
Furan/phenylene co-oligomer single crystals are considered as future materials for organic optoelectronics. Here, the effects of trifluoromethyl substituents on the crystallization, structure and optical properties of furan/phenylene co-oligomer 1,4-bis{5-[4-(trifluoromethyl)phenyl]furan-2-yl}benzene are studied systematically. The solution growth methods and physical vapor transport result in the formation of three polymorphs depending on the growth method and the solvent. Single-crystal X-ray analysis reveals the crystal structures to correspond to H-, J- or mixed aggregates...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297550/determination-of-the-miscibility-gap-in-the-solid-solutions-series-of-methylammonium-lead-iodide-chloride
#3
Alexandra Franz, Daniel M Többens, Julia Steckhan, Susan Schorr
Perovskites are widely known for their enormous possibility of elemental substitution, which leads to a large variety of physical properties. Hybrid perovskites such as CH3 NH3 PbI3 (MAPbI3 ) and CH3 NH3 PbCl3 (MAPbCl3 ) are perovskites with an A[XII] B[VI] X[II] 3 -structure, where A is an organic molecule, B is a lead(II) cation and X is a halide anion of iodine or chlorine. Whereas MAPbCl3 crystallizes in the cubic space group Pm{\overline 3}m, MAPbI3 is in the tetragonal space group I4/mcm. The substitution of I by Cl leads to an increased tolerance against humidity but is challenging or even impossible due to their large difference in ionic radii...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297549/inflexible-stoichiometry-in-bulk-pyrite-fes-2-as-viewed-by-in-situ-and-high-resolution-x-ray-diffraction
#4
Rebecca D McAuliffe, Daniel P Shoemaker
Non-stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS2 , as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS2-δ with δ up to 0.25, the current consensus based on calculated formation energies of intrinsic defects has lent support to line-compound behavior. Here it is shown that pyrite stoichiometry is relatively inflexible in both reductive conditions and in autogenous sulfur partial pressure, which produces samples with precise stoichiometry of FeS2 even at different Fe/S ratios...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297548/triethylphosphine-as-a-molecular-gear-phase-transitions-in-ferrocenyl-acetylide-gold-i
#5
Anna Makal
A sequence of two discontinuous phase transitions, occurring just above 125 K and 148 K, has been observed for a ferrocenyl-acetylide-gold(I) complex with triethylphosphine, structure (1), by means of a multi-temperature single-crystal X-ray diffraction technique. Three distinct phases have been identified. The high-temperature α and low-temperature γ phases share the same space group Pbca, whereas the intermediate β phase is in the Pb21 a subgroup of Pbca. In all phases molecules of (1) form well defined double layers, with PEt3 groups interlocking in planes perpendicular to c...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297547/azulene-revisited-solid-state-structure-invariom-modeling-and-lattice-energy-minimization-of-a-classical-example-of-disorder
#6
B Dittrich, F P A Fabbiani, J Henn, M U Schmidt, P Macchi, K Meindl, M A Spackman
The molecular and solid-state structure of azulene both raise fundamental questions. Therefore, the disordered crystal structure of azulene was re-refined with invariom non-spherical atomic scattering factors from new single-crystal X-ray diffraction data with a resolution of d = 0.45 Å. An unconstrained refinement results in a molecular geometry with Cs symmetry. Refinements constrained to fulfill C2v symmetry, as observed in the gas phase and in high-level ab initio calculations, lead to similar figures of merit and residual densities as unconstrained ones...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297546/the-puzzling-structure-of-cu-5-fes-4-bornite-at-low-temperature
#7
Alberto Martinelli, Giovanni Orazio Lepore, Fabio Bernardini, Andrea Giaccherini, Francesco Di Benedetto
The crystal structure of Cu5 FeS4 (bornite) has been investigated using synchrotron X-ray powder diffraction at temperatures between 10 and 275 K. Diffraction data confirm that bornite crystallizes in the orthorhombic space group Pbca at 275 K. The unit-cell volume decreases continuously on cooling, but undergoes an abrupt contraction below ∼65 K, where a first-order Pbca→Pca21 structural transition takes place. The primary active mode yielding the observed ordered structure corresponds to the irreducible representation Γ2 - , with wavevector (0,0,0)...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30297545/crystalline-transformers-more-within-than-meets-the-eye
#8
Larry R Falvello
Studies of phase transitions in molecular crystals are becoming more commonplace as improvements in instrumentation and technique enable more efficient exploration of the behavior of samples with varying external conditions, usually temperature. This scientific commentary provides contextual background on this type of study, with reference to an article on transformations in a ferrocenyl-acetylide-gold(I) complex [Makal (2018). Acta Cryst. B74, 427-435].
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141425/compositionally-induced-phase-transitions-and-symmetry-relations-between-space-groups-in-the-layered-system-fein-1-x-y-x-ge-2-o-7
#9
Rosario Moreno-Tovar, Lauro Bucio, Ivonne Rosales, Eligio Orozco
Symmetry reduction in the basic structure of thortveitite-type compound FeInGe2 O7 -mC22 (C12/m1, No. 12) promoted by the incorporation of yttrium in the formula FeIn1-x Yx Ge2 O7 gives rise to a derivative structure called thortveitite-like AA'Ge2 O7 -mP44, with symmetry described by the space group P121 /m1 (No. 11) for x = 0.50, 0.75 and 0.90. The structure remains unchanged within the structural type of thortveitite when x = 0.25. In order to establish structural models for performing a Rietveld refinement to the derivative structure, symmetry relations between space groups connecting the basic and derivative structures were used...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141424/high-density-hniw-tnt-cocrystal-synthesized-using-a-green-chemical-method
#10
Yan Liu, Chongwei An, Jin Luo, Jingyu Wang
The main challenge for achieving better energetic materials is to increase their density. In this paper, cocrystals of HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, often referred to as CL-20) with TNT (2,4,6-trinitrotoluene) were synthesized using ethanol in a green chemical method. The cocrystal was formulated as C13 H11 N15 O18 and possesses a higher density (1.934 g cm-3 ) than published previously (1.846 g cm-3 ). This high-density cocrystal possesses a new structure, which can be substantiated by the different types of hydrogen bonds...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141423/similarities-and-differences-in-the-crystal-packing-of-halogen-substituted-indole-derivatives
#11
Rahul Shukla, Paramveer Singh, Piyush Panini, Deepak Chopra
The role of different intermolecular interactions in the crystal structures of halogen-substituted indoles which are fused with six-membered or seven-membered cyclic rings is investigated here. Several crystal structures show isostructural characteristics due to the presence of similar supramolecular motifs. In the absence of any strong hydrogen bonds, the molecular packing of reported structures is primarily stabilized by the presence of non-classical N-H...π and C-H...π interactions in addition to C-H....
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141422/-al-mg-3-la-a-new-phase-in-the-mg-al-la-system
#12
Charlotte Wong, Mark J Styles, Suming Zhu, Dong Qiu, Stuart D McDonald, Yuman Zhu, Mark A Gibson, Trevor B Abbott, Mark A Easton
During an investigation of the Mg-rich end of the Mg-Al-La system, a new ternary phase with the composition of (Al,Mg)3 La was identified. The crystal structure of this phase was determined by conventional X-ray powder diffraction and transmission electron microscopy analysis and refined using high-resolution X-ray powder diffraction. The (Al,Mg)3 La phase is found to have an orthorhombic structure with a space group of C2221 and lattice parameters of a = 4.3365 (1) Å, b = 18.8674 (4) Å and c = 4...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141421/nollmotzite-mg-u-v-u-vi-o-2-2-o-4-f-3-%C3%A2-4h-2-o-the-first-natural-uranium-oxide-containing-fluorine
#13
Jakub Plášil, Anthony R Kampf, Radek Škoda, Jiří Čejka
Nollmotzite (IMA2017-100), Mg[UV (UVI O2 )2 F3 O4 ](H2 O)4 , is a new uranium oxide fluoride mineral found in the Clara mine, Black Forest Mountains, Germany. Electron microprobe analysis provided the empirical formula (Mg1.06 Cu0.02 )Σ1.08 [UV (UVI O2 )2 O3.85 F3.15 ][(H2 O)3.69 (OH)0.31 ]Σ4.00 based on three U and 15 O + F atoms per formula unit. Nollmotzite is monoclinic, space group Cm, with a = 7.1015 (12) Å, b = 11.7489 (17) Å, c = 8.1954 (14) Å, β = 98.087 (14)°, V = 676.98 (19) Å3 and Z = 2...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141420/control-of-crystal-structure-using-temperature-and-time
#14
Savannah C Zacharias, Gaëlle Ramon, Susan A Bourne
Three novel crystal structures were obtained from iron(III) acetylacetonate and 2,6-pyridinedicarboxylic acid. The structures elucidated were found to be dependent on the temperature and length of time allowed for the reaction. The product of the reaction between iron(III) acetylacetonate and 2,6-pyridinedicarboxylic acid in acetonitrile at room temperature is [FeC12 H12 NO7 ]·CH3 CN, (I). When the reaction temperature was increased to 60°C, FeC12 H10 NO6 , (II), was isolated after 2 h and [FeC12 H10 NO6 ]4 , (III), was isolated after 24 h...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141419/vanadium-clusters-formation-in-geometrically-frustrated-spinel-oxide-alv-2-o-4
#15
Mikhail V Talanov, Vladimir B Shirokov, Leon A Avakyan, Valeriy M Talanov, Khisa Sh Borlakov
The spinel oxide AlV2 O4 is a unique material, in which the formation of clusters is accompanied by atomic, charge and orbital ordering and a rhombohedral lattice distortion. In this work a theory of the structural phase transition in AlV2 O4 is proposed. This theory is based on the study of the order-parameter symmetry, thermodynamics, electron density distribution, crystal chemistry and mechanisms of formation of the atomic and orbital structures of the rhombohedral phase. It is established that the critical order parameter is transformed according to irreducible representation k9 (τ4 ) (in Kovalev notation) of the Fd \bar{3}m space group...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141418/jinshajiangite-structure-twinning-and-pseudosymmetry
#16
Shiyun Jin, Huifang Xu, Seungyeol Lee, Pingqiu Fu
The crystal structure of jinshajiangite based on a sample from its original discovery location is studied using single-crystal X-ray diffraction and transmission electron microscopy methods. Jinshajiangite is a titanium silicate mineral with an ideal chemical formula of BaNaFe4 Ti2 (Si2 O7 )2 O2 (OH)2 F. The structure of jinshajiangite is of P\bar 1 symmetry (triclinic system), with a = 8.7331 (2) Å, b = 8.7366 (2) Å, c = 11.0404 (3) Å, α = 81.477 (1)°, β = 110.184 (1)°, γ = 104.384 (1)° and V = 764...
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/30141417/crystallographic-searches-for-weak-interactions-the-limitations-of-data-mining
#17
Hans Jörg Schneider
No abstract text is available yet for this article.
August 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927394/hydrophobic-dipeptides-the-final-piece-in-the-puzzle
#18
Carl Henrik Görbitz
The crystal structure of L-valyl-L-leucine acetonitrile solvate presented here adds to 24 previously reported structures of dipeptides constructed from the five nonpolar amino acids L-alanine, L-valine, L-isoleucine, L-leucine and L-phenylalanine. It thus constitutes the final piece in the 5 × 5 puzzle of hydrophobic dipeptide structures. This opportunity is taken to review the crystal packing arrangements and hydrogen-bonding preferences of a rather unique group of substances, with updated information on the various hydrogen-bonding patterns and the associated peptide conformations...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927393/a-crystallographic-and-thermal-study-of-pridinol-mesylate-and-its-monohydrated-solvate
#19
Pablo Gaztañaga, Ricardo Baggio, Daniel Roberto Vega
Herein are reported the crystal and molecular structures of the pridinol mesylate salt (C20 H25 NO+ ·CH3 O3 S- ) (I) and its monohydrated solvate form (C20 H25 NO+ ·CH3 O3 S- ·H2 O) (II). A comparison of both with the already reported structure of pure pridinol [1,1-diphenyl-3-piperidino-1-propanol, C20 H25 NO; Tacke et al. (1980). Chem. Ber. 113, 1962-1980] is made. Molecular structures (I) and (II) are alike in bond distances and bond angles, but differ in their spatial conformation, and, more relevant still, in their hydrogen-bonding motifs...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/29927392/structure-of-russellite-bi-2-wo-6-origin-of-ferroelectricity-and-the-effect-of-the-stereoactive-lone-electron-pair-on-the-structure
#20
Hiroki Okudera, Yuka Sakai, Kentaro Yamagata, Hiroaki Takeda
The structure of the low-temperature polar (orthorhombic) phase of russellite (Bi2 WO6 ) was examined on artificial specimens with precise single-crystal X-ray diffraction experiments. The final atomic arrangement thus obtained was identical to that reported by Knight [Miner. Mag. (1992), 56, 399-409] with powder neutron diffraction. The residual density attributable to a stereochemically-active lone pair of electrons of bismuth was prominent at approximately the centre of a larger cap of BiO8 square antiprisms, that is on the line from the Bi sites to an adjacent WO4 2- slab along the b-axis direction...
June 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
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