The following articles are a selection of those recently accepted for publication in Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials.
Why direct and post-refinement determinations of absolute structure may give different results
Comparison of direct and post-refinement methods for determining the Flack absolute structure parameter provides a mechanism for exposing deficiencies in a structure analysis. A substantial discrepancy is often indicative of underlying problems with the data and/or structural model.
Accurate unrestrained DDM refinement of crystal structures from highly distorted and low-resolution powder diffraction data
Crystal structures of benzene:ethane co-crystal and 2-aminopyridinium-fumarate-fumaric acid are refined without geometric restraints using the derivative difference method from strongly distorted synchrotron and low-resolution laboratory X-ray powder diffraction data. The results are compared with DFT calculations and former restrained Rietveld refinements for the same datasets.
Variable temperature X-ray diffraction study of structural parameters of NH---S hydrogen bonds in triethylammonium and pyridinium silanethiolates
Hydrogen bonds in triethylammonium and pyridinium silanethiolate salts have been characterized by X-ray, FT-IR and NMR spectroscopies. DFT calculations reveal strongly assymetric double-well minima at the potential energy curves of the studied compounds.
Mutual transformation between crystalline phases in silicon after treatment in a planetary mill. HRTEM studies
Silicon particles after treatment in a planetary mill have been examined in TEM. It is shown that along with the initial phase of silicon, Si-I, the sample also contains some high pressure phases: Si-III (Kasper phase) and Si-IV (lonsdaleite). We studied the orientation relationship between the particles of different phases.
Topological characterization of electron density, electrostatic potential and intermolecular interactions of 2-nitroimidazole: an experimental and theoretical study
In this paper we present a detailed investigation of experimental and theoretical charge density analysis and electrostatic properties of the 2-nitroimidazole molecule. The topological properties of electron density reveal the charge density distribution of the molecule and non-bonding regions.
Structures and physicochemical properties of vortioxetine salts
Eight salts of vortioxetine were synthesized and structurally elucidated by single-crystal structure analysis. Physical and chemical properties were evaluated by a variety of analytical techniques. The vortioxetine aspartate dihydrate shows a higher solubility and dissolution rate with respect to the pure drug.
CH3NH3PbI3: precise structural consequences of water absorption at ambient conditions
Structure, symmetry and hydrogen bonds have been determined for pristine and aged tetragonal CH3NH3PbI3 crystals upon H2O absorption from air at room temperature. Single-crystal X-ray diffraction data obtained on a synchrotron light source was used for the study. H2O insertion into the structure changes hydrogen bonds and, consequently, the space group from I422 (pristine crystal) to P42212 (aged crystal).
Communication between cation environments in aluminosilicate frameworks: incommensurately modulated crystal structure of an e-plagioclase
Plagioclase is known as one of the most common mineral exhibits in the earth's crust, but is also known for its complicated crystal structure. In this article we present a full detailed analysis of the incommensurately modulated structure of intermediate e-plagioclase (An44), and highlight how it originates from the coupling between the coordination environments of its cations.
Towards a revisitation of vesuvianite-group nomenclature: the crystal structure of Ti-rich vesuvianite from Alchuri, Shigar Valley, Pakistan
Vesuvianite containing 5.85 wt% TiO2 from an Alpine-cleft-type assemblage outcropped near Alchuri, Shigar Valley, Northern Areas, Pakistan, has been studied. The role of the Y1 site in the diversity of vesuvianite-group minerals is discussed.
Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth
In view of future exploitation of intrinsic Josephson junctions (IJJs) for solid-state THz applications, we synthesized high-quality superconducting YBCO tape-like single crystals (whiskers) from Ca–Al-doped precursors in the presence of Te. Firstly, we aim to carry out the importance of the simultaneous use of Ca, Te and Al in promoting YBCO whiskers growth with superconducting properties, then to fill the lack of YBCO structure investigations in the literature by reporting single-crystal X-ray diffraction refinements of tetragonal YBCO.
Br⋯Br and van der Waals interactions along a homologous series: crystal packing of 1,2-dibromo-4,5-dialkoxybenzenes
The crystalline structures of four homologues of the 1,2-dibromo-4,5-dialkoxybenzene series [Br2C6H2(OCnH2n + 1)2 for n = 2, 12, 14 and 18] have been solved by means of single-crystal crystallography.
Bis-(1-(2-Aminoethyl)piperidino), (2-(2-aminoethyl)pyridino) and (1-(2-aminoethyl)pyrrolidino)-substituted dicyanoquinodimethanes: consequences of flexible ethylene spacers with heterocyclic moieties and amine functionalities
Synthesis and characterization of new functional molecular materials based on disubstituted tetracyanoquinodimethanes
Two rhodamine 6G derivative compounds: a structural and fluorescence single-crystal study
The synthesis, characterization, structural analysis and fluorescence properties of two rhodamine 6G derivatives are described. A single-crystal in-situ reaction study is presented, carried out by fluorescence methods, which enabled the `opening' of the spirolactam ring in the solid phase.