Acta Cryst. (2012). B68, 215-226
[ doi:10.1107/S0108768112017466 ]

Constrained evolutionary algorithm for structure prediction of molecular crystals: methodology and applications

Q. Zhu, A. R. Oganov, C. W. Glass and H. T. Stokes

Synopsis: A specially designed algorithm to predict the structure of complex crystals consisting of well defined molecular units is presented.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 227-239
[ doi:10.1107/S010876811201419X ]

Structural chemistry of A₂MX₄ compounds (X = O, F) with isolated tetrahedral anions: search for the densest structure types

V. Nalbandyan and A. Novikova

Synopsis: In three of the nine morphotropic A₂MX₄ series (nine different tetrahedral anions) the densest structure (spinel) is the stable structure for compounds with A cations of intermediate radius, in contrast to the classical homology rule. In some cases, denser phases have abnormally low overall binding energies.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 240-249
[ doi:10.1107/S0108768112008038 ]

Helical screw type magnetic structure of the multiferroic CaMn₇O₁₂ with low Cu-doping

W. Slawinski, R. Przenioslo, I. Sosnowska and V. Petrícek

Synopsis: The modulated crystal structure and modulated magnetic ordering of the multiferroic CaCu_xMn_7-xO₁₂ is studied by analysing neutron and synchrotron-radiation powder diffraction data with a model based on the magnetic superspace group R31'(00)ts.

Online 4 May 2012

 

Acta Cryst. (2012). B68, 250-260
[ doi:10.1107/S0108768112016084 ]

Structure of (Ga₂O₃)₂(ZnO)₁₃ and a unified description of the homologous series (Ga₂O₃)₂(ZnO)_2n + 1

Y. Michiue, N. Kimizuka, Y. Kanke and T. Mori

Synopsis: The structure of (Ga₂O₃)₂(ZnO)₁₃ has been determined and a unified description for structures in a homologous series (Ga₂O₃)₂(ZnO)_2n + 1 is presented using the (3 + 1)-dimensional superspace formalism.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 261-265
[ doi:10.1107/S0108768112012281 ]

Parallel stacking interactions in square-planar transition-metal complexes containing fused chelate and C₆-aromatic rings

D. N. Sredojevic, D. Z. Vojislavljevic, Z. D. Tomic and S. D. Zaric

Synopsis: The study of C_6-arom-chelate versus C_6-arom-C_6-arom stacking interactions in the crystal structures of square-planar transition metal complexes showed that the C_6-arom ring prefers to form stacking contacts with the chelate rings.

Online 4 May 2012

 

Acta Cryst. (2012). B68, 266-274
[ doi:10.1107/S0108768112011226 ]

Phase transition at high pressure in Cu₂CO₃(OH)₂ related to the reduction of the Jahn-Teller effect

M. Merlini, N. Perchiazzi, M. Hanfland and A. Bossak

Synopsis: Malachite, Cu₂CO₃(OH)₂, transforms directly into a rosasite structure at high pressure as a result of the pressure-induced reduction of the Jahn-Teller distortion of CuO₆ coordination polyhedra.

Online 4 May 2012

 

Acta Cryst. (2012). B68, 275-286
[ doi:10.1107/S0108768112015960 ]

Effect of pressure on crystalline L- and DL-serine: revisited by a combined single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy study

B. A. Zakharov, B. A. Kolesov and E. V. Boldyreva

Synopsis: Information on the effect of pressure on hydrogen bonds, which could be derived from single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy, has been compared.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 287-296
[ doi:10.1107/S0108768112015972 ]

Low-temperature phase transition in glycine-glutaric acid co-crystals studied by single-crystal X-ray diffraction, Raman spectroscopy and differential scanning calorimetry

B. A. Zakharov, E. A. Losev, B. A. Kolesov, V. A. Drebushchak and E. V. Boldyreva

Synopsis: A low-temperature reversible phase transition at 220-230 K in glycine-glutaric acid co-crystals changes the conformation of every second glutaric acid molecule, but preserves the topology of the hydrogen-bond network, despite changes to the hydrogen-bond lengths and the space-group symmetry.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 297-304
[ doi:10.1107/S0108768112010993 ]

Relation between photochromic properties and molecular structures in salicylideneaniline crystals

K. Johmoto, T. Ishida, A. Sekine, H. Uekusa and Y. Ohashi

Synopsis: Salicylideneaniline crystals exhibit photochromism under the following conditions: the dihedral angle between the two terminal benzene rings is greater than 30° and there is no intra- or intermolecular steric hindrance to inhibit a pedal motion within the crystal.

Online 4 May 2012

 

Acta Cryst. (2012). B68, 305-312
[ doi:10.1107/S0108768112014711 ]

Voronoi-Dirichlet tesselation as a tool for investigation of polymorphism in molecular crystals with C_wH_xN_yO_z composition and photochromic properties

V. N. Serezhkin, L. B. Serezhkina and A. V. Vologzhanina

Synopsis: A relationship between photochromism and non-bonded interactions was investigated with the Voronoi-Dirichlet approach. Crystal structures of five sets of conformational polymorphs with the C_wH_xN_yO_z composition have been taken into account. It was demonstrated that each polymorph is characterized by a unique set of inter- and intramolecular contacts.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 313-317
[ doi:10.1107/S0108768112017831 ]

Invariom modeling of ceftazidime pentahydrate: molecular properties from a 200 second synchrotron microcrystal experiment

C. J. Schürmann, K. Pröpper, T. Wagner and B. Dittrich

Synopsis: The structure of ceftadizime pentahydrate was determined from a 200 s experiment with synchrotron radiation. Combined with invariom refinement for rapid property calculation, high-throughput electron-density studies of hundreds of compounds become feasible.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 318-320
[ doi:10.1107/S0108768112020289 ]

Exact solution of the bond-valence sum rule for a set of coordination shells

V. Sidey

Synopsis: The calculation scheme for determining the bond-valence parameters (r₀ and b) resulting in the exact solution of the bond-valence sum rule for a given set of coordination shells is presented.

Online 17 May 2012

 

Acta Cryst. (2012). B68, 321
[ doi:10.1107/S0108768112018551 ]

Symmetriebeziehungen zwischen verwandten Kristallstrukturen

Online 17 May 2012