issue contents

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

October 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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Contrary to the well known modulated structures with sharp satellite reflections, the diffraction pattern of a short-range modulated structure contains diffuse satellite reflections. The crystal structure of NaNO2 above TN = 437.7 K in the paraelectric phase is short-range modulated with remnants of distorted fragments of a sinusoidal modulation.

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The structure phase transition of GdFe_3(BO_3)_4 is investigated. A single-crystal X-ray structure study is reported at room temperature and at T = 90 K. The low-temperature space group found is P3121.

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In this work we show that in a 14 nm-thick NiSi layer, the silicide lattice can three-dimensionally adapt to that of a [001]-oriented Si substrate by forming transrotational domains. The resulting structural properties are promising to improve the structural and electrical stability of very thin NiSi layers.

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The crystal structures of Sb–Te compounds that are materials currently used for DVDs were investigated by powder X-ray diffraction using synchrotron radiation. Each structure is fundamentally a simple stacking structure, but the stacking period changes regularly with composition and becomes extremely long.

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The crystallographic mechanism of the pressure-induced transformation of turbostratic graphite-like BN–C solid solutions at room temperature has been studied by Rietveld analysis and numerical modeling.

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An automated method to scan a total of over 325 000 small-molecule crystal structures in the Cambridge Structural Database for polymorphs is described. The results for 35 000 pairs of crystal structures are reported: 308 previously unknown individual polymorphs were identified.


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Extended lists of the hypothetical crystal structures of two small semi-rigid molecules, submitted in the third Cambridge blind test of crystal structure prediction, were analyzed for completeness and correlation between energies.

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Morphotropism (i.e. the non-crystallographic rotation of motifs) bridges the phenomena of isostructurality, polymorphism and (stereo)isomerism. Various forms of virtual and effective rotation of the common motifs, through either 90 or 180°, between chemically related structures, are presented.

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A visualization of diversity in structural databases by mapping powder diffraction patterns in a two-dimensional self-organizing map is presented, including principles and applications.

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A new approach to the crystal structure prediction of flexible molecules is described and illustrated using a `blind' prediction of a recently solved conformational polymorph of piracetam.

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The crystal structures of five new xanthinic derivatives acting as adenosine antagonists have been determined. Other molecules of known biological activity have been reported and compared, with the aim of understanding the structural features controlling their affinity capabilities and selectivity.

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The α-polymorph of the energetic material 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (NTO) crystallizes as a four-component triclinic twin (fourling). The twin laws are rationalized on the basis of the symmetry of a pseudo-orthorhombic superstructure and the molecular packing.

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A probabilistic model is used to group the eight-membered ring conformations using the intra-ring torsion angles. Hints about the interconversion pathways between conformations are also obtained.

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The pressure-frozen structure of CH2Cl2 has been determined by single-crystal X-ray diffraction at 1.33 and 1.63 GPa, and the intermolecular electrostatic, halogen⋯halogen and H⋯halogen crystal cohesion forces have been analysed.
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