issue contents

ISSN: 2052-5206

August 2013 issue

Highlighted illustration

Cover illustration: Reduction of volumes of the voids in the crystal structures of DL-alanine and L-alanine on application of 6 GPa of pressure. Yellow voids are shown within the ball-and-stick structure models. The molecules as well as the topologies and symmetries of their packings are preserved over the whole pressure range of 0-6 GPa. See Fig. 4 in Tumanov & Boldyreva [(2012), Acta Cryst. B68, 412-423].


lead articles

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Crystal structure prediction methods usually generate more thermodynamically feasible structures than known polymorphs. Some reasons for this are discussed in the light of studies where computed crystal energy landscapes have been contrasted with experimental searches for solid forms.

research papers

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The origins and features of incommensurate structural modulation are discovered in a single crystal of Lu4AlCu2B9O23 on cooling down to 110 K.

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The proton ordering plays an important role in the structural phase transitions of (NH4)3H(SO4)2 at low temperature. Crystal structure analysis using neutron diffraction reveals a sequential ordering of the ammonium groups and of the proton in the (SO4)H(SO4) dimer with decreasing temperature, related to the different phase transitions.

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Charge density distribution in tetralithium hypodiphosphate hexahydrate Li4P2O6·6H2O has been studied experimentally and by theoretical calculations; the reasons for the rigidity of the electron density distribution in the hypodiphosphate anion are discussed.

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The extended Zintl–Klemm concept accounts for the structures of the three dimeric cyclotrisilicate anions [Si6O17]10−, [Si6O16]8− and [Si6O15]6− as Zintl polyanions of composition [Ψ-S4P2]10−, [Ψ-S2P4]8– and [Ψ-P6]6−, respectively.

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Crystal structure of domperidone {or 5-chloro-1-(1-[3-(2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)propyl]piperidin-4-yl)-1H-benzo[d]imidazol-2(3H)-one} and domperidone succinate salt. The domperidone succinate salt shows higher solubility and dissolution rate with respect to the pure drug.

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In this contribution different solid-state forms of the racemic compound (RS)-2-(2-oxo-pyrrolidin-1yl)-butyramide are studied from a structural and thermal point of view and compared to the enantiopure compound.

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Analysis of 770 structures containing chloroform and 919 structures containing dichloromethane shows that around 80% of both molecules use their acidic C—H protons in hydrogen-bond formation in crystal structures, but their Cl atoms would appear to make only a limited contribution to crystal aggregation.

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Parallel stacking interactions between pyridine molecules in crystal structures and the influence of supramolecular structures in crystals on the geometry of interactions were studied by analyzing data in the Cambridge Structural Database (CSD).

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The crystal structure of the title compound was solved from neutron powder diffraction data and refined by energy minimization in the solid state. Weak intermolecular interactions were analysed by theoretical molecular calculations.

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The structures of three methyl-substituted thioureas and three related adducts with morpholine or 1,4-dioxane are presented and their hydrogen-bonding patterns discussed.

short communications

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A recently proposed method to calculate the a parameter of the unit cell of layered double hydroxides from the fraction of trivalent cations is extended to Zn- and Co-based phases. It is shown to be useful as a sanity test for extant and future structure determinations and computer-simulation studies.

book reviews

Acta Cryst. (2013). B69, 418
doi: 10.1107/S2052519213012141
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