issue contents

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

April 2008 issue

Highlighted illustration

Cover illustration: The cover picture shows the strong and highly structured diffuse scattering from polymorph (II) of N-(p-methylbenzylidene)-p-methylaniline (MeMe) and indicates strongly correlated molecular motion not apparent from the Bragg analysis. Unlike polymorphs (I) and (III), which are disordered, polymorph (II) appears from Bragg scattering to be a perfectly normal ordered molecular crystal. The section of diffuse scattering data shown is part of a full three-dimensional data set recorded on beamline 1-ID-C at the Advanced Photon Source at Argonne, Illinois. Courtesy of Professor T. R. Welberry and Andrew Beasley.

research papers


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Re-examination and quantum optimization of kaolin layer stackings allow the construction of a rough enthalpy versus pressure graph with 36 stackings where kaolinite and dickite are low-energy solutions, whereas nacrite and HP-dickite are low-enthalpy solutions at moderate pressures; minor temperature dependence of this calculated 0 K graph would explain the bulk of the current observations for synthesis, diagenesis and transformation of kaolin minerals. The ideal model of nacrite is one member of a homometric but energy-distinguishable pair, whereas its literature-printed structure is correctly that of the stable member.

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A new structural model has been determined for the [Ca2CoO3][CoO2]1.62 misfit lamellar cobalt oxide compound. It can be described with a new commensurable modulation implied by a partial ordering within the [CoO] layer.

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Ba3CaSb2O9 and Ba3SrSb2O9 are 6H perovskites with monoclinic C2/c and triclinic P\bar 1 symmetries, respectively. Their distortions from the ideal hexagonal P63/mmc symmetry of Ba3MgSb2O9 are due to the increasing size of the alkaline-earth cation in the perovskite B site from Mg2+ to Ca2+ to Sr2+.

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The new incommensurately modulated scheelite-like structure of KSm(MoO4)2 with partially disordered K and Sm has been refined by the Rietveld method. Anisotropic microstrain line-broadening has been applied to the profile refinement of the powder diffraction measurement. The fit is greatly improved in comparison with standard isotropic line-broadening.


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A new homologous series of oxygen-vacancy-ordered perovskite compounds with the formula Sr_{4+n}Mn^{3+}_4Mn^{4+}_nO_{10+3n} is described. Rules for generating these compounds are given in the form of simple building blocks formed by Mn3+O5 pyramids and Mn4+O6 octahedra. Related compounds in the CaMnOx and LaCuOx systems have also been identified as members of the proposed series.

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The crystal structures of two polymorphs of cis-PtCl2(Bz2S)2 at 295, 250, 200, 150 and 100 K are reported with emphasis on crystal packing. The structural class distribution for cis-PtX2L2 (X = halogen, L = neutral ligand) is given together with an analysis of the trans and cis influence in cis/trans-PtCl2L2 complexes.

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Cyclic oxazaphospholidines and oxazaphosphinanes develop linear molecular chains bonded by relatively weak XH⋯O=P interactions (X = C, N); the chains themselves are sometimes weakly linked by CH\cdots\pi or other CH⋯O interactions.


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The inclinations of the two aryl rings (ring twists) in a series of 104 benzophenone molecules have been examined. Six new benzophenone structures are incorporated into the study including 2,2′-dihydroxy-4,4′-dimethoxybenzophenone that appears to have the smallest reported twist angle of any substituted benzophenone reported to date.

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The molecular and crystal structure of a new nitrogen–sulfur pro-ligand used in the design of metal organic compounds with potential applications in inorganic biomimetic catalysis, cycloheptanespiro-3′(4′H)-6′,7′,8′,9′-tetrahydrocyclohexa[b][1,4]thiazole-2′(5′H)-thione, was solved and refined using synchrotron powder X-ray diffraction data.

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Two pseudopolymorphs of N-acetyl-L-phenylalanine methyl ester were obtained, namely an anhydrous orthorhombic phase and a hemihydrate tetragonal phase. Spontaneous re-crystallization of the anhydrous compound to the hemihydrate is observed in the presence of a trace amount of water.

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Three complete neutron diffraction datasets have been collected on deuterated malonic acid single crystals, DOOC(CD2)COOD, above (153 K), just below (56 K) and further below (50 K) the low-temperature phase transition (Tc = 56.5 K). The full structural details, determined from refinements including higher-order displacement tensors, are related to those from other aliphatic dicarboxylic acids subject to polymorphism.

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The β-2 crystal structures of a series of saturated and trans-mono-unsaturated triacylglycerols have been solved from high-resolution powder synchrotron diffraction data. Most postulations about the packing of these polymorphs are confirmed.

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The crystal structures of the β_1^{\prime}-2 polymorph of a series of mixed-chain saturated and trans-mono-unsaturated triacylglycerols have been solved from high-resolution powder diffraction data. A novel β′-2 polymorph of PSS has been found and its structure has been solved.
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