issue contents

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

December 2005 issue

Highlighted illustration

Cover illustration: The arrangements of boxes shown represent the possible packing patterns of four molecules (each with dimensions L, M and S) in a unit cell, as described by the Box Model of crystal packing [Pidcock & Motherwell (2004). Cryst. Growth Des., 4, 611-620]. Application of this model to experimental P21/c structures revealed that the lower surface area packing patterns, for example 221L and 221M, are populated to a much greater extent than the higher surface area packing patterns of 114M and 114L. This finding indicates molecular shape is of primary importance in crystal packing [Pidcock & Motherwell (2004), Acta Cryst. B60, 539-546; Pidcock & Motherwell (2004), Acta Cryst. B60, 725-733].

research papers


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The interactions between C atoms and Na ions can be directly associated with the phase transitions in sodium carbonate, Na2CO3. By lowering the temperature, the coordination number of the C atoms increases from 3 to 7 in the second coordination sphere. The behavior of the carbonate ion is influenced by the neighbouring Na ions.

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Probability density distributions of the K ion in the title compounds were examined by single-crystal X-ray diffraction. A Gram–Charlier expansion was used for the atomic displacement parameters.

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An examination of tilts and their relationships to acoustic modes is made for simple perovskite structure types. The origin of the incommensurate phases in the organic–inorganic perovskites is shown to be due to the coupling of low-frequency buckling modes which are intrinsic to the inorganic layer with the onset of orientational ordering of the amine cations.

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Twinning in the structure of deca-dodecasil 3R has been resolved and a new structure determination is presented. Ab initio molecular dynamics calculations show that disorder in deca-dodecasil 3R is dynamic rather than static in nature.

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A geometrical crystal-chemical model of P63/m apatite based on a specific set of bond-length and bond-angle parameters is derived. The model is used to compare the experimental results of apatite materials studied by single-crystal and Rietveld analysis with computed results of ab initio simulations, which are also used to predict the structures of hypothetical compounds which have not yet been studied.

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Single-crystal XRD experiments at 1100 K show that the compound Ca2Fe2O5 forms an incommensurately modulated structure. The modulation can be explained with aperiodic alternation of enantiomorphic tetrahedral chains.

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Both Na9[SO4]4Cl·2H2O2 and its newly discovered bromide analogue are extremely stable and can be used as sources of anhydrous H2O2 or, in the presence of H+, dihalogen. Despite being composed of small, inorganic molecules and ions, long H2O2 orientation sequences require the chloride unit-cell dimensions to be exceptionally large. The extended patterns of H2O2 orientations can be linked to displacements of the eight sodium cations that coordinate each halide anion.

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The crystal structure of Cd3(O3PC2H4CO2)2·2H2O has been determined from in-house powder data. This compound crystallizes in the monoclinic system and shows a layered-type structure in which the layers are connected by the ligand into a three-dimensional array.

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The modulated structures of [M(H2O)2(15-crown-5)](NO3)2, M = Cu, Zn, Mg and Co, have been redetermined at 294 and 90 K. Significant problems in the original determinations have been fixed, the relationships between the structures have been identified and a reason for the modulations has been proposed.

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The structure of highly twinned pinacol monohydrate has been determined, and the structures of anhydrous pinacol and its two other known hydrates have been reinvestigated.

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The isostructural phase transition of the title compound and its 3.6 K hysteresis (Tc = 246 K on cooling and 249.6 K on heating) have been characterized by X-ray diffraction and differential scanning calorimetry.

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The crystal structure of the major diabetes treatment glipizide (glucotrol) has been determined. Intermolecular forces have been quantitatively evaluated from analysis of the thermal expansion of the lattice.

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The crystal structure of cyclopropylamine has been determined at 1.2 GPa using high-pressure single-crystal X-ray diffraction techniques. The structure of this previously unobserved phase is orthorhombic.

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Temperature-dependent proton migration has been observed in pyridine-3,5-dicarboxylic acid and also in pyridine-3,5-dicarboxylic acid in which the carboxylic acid protons have been replaced by deuterons.
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