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Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

June 2021 issue

Highlighted illustration

Cover illustration: The crystal structure of the uranyl arsenate mineral hügelite [Pb2(UO2)3O2(AsO4)2(H2O)5] projected down the monoclinic b axis (see Plášil et al., pp. 378–383).

scientific commentaries


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The small-molecule crystallographic community has recently begun to assess the radiation damage impact of high intensity beams on samples. Bogdanov et al. [Acta Cryst. (2021), B77, 365–370] investigate the radiation damage impact on molecular ferroelectric crystal glycinium phosphite.

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A brief insight is presented into thermal expansion of organic molecular crystals with reference to the recent article by Andrew Bond [Acta Cryst. (2021), B77, 357–364].

quantum crystallography


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High-level quantum chemical calculations provide quantitative insights into the nature of intermolecular interactions in the stacking systems of tetra­thia­fulvalene and selected derivatives.

high-pressure crystallography


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High pressure influences the formation of the products during the photochemical reaction in crystals of (S)-(−)-1-phenyl­ethan­aminium 4-(2,4,6-tri­iso­propyl­benzoyl)­benzoate. The reason for this behaviour is the changing geometry of the molecules and their surroundings along with the change in pressure.

research papers


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An ultra-high-resolution crystal structure of Z-DNA with the sequence d(CGCGCG)2 reveals the pattern of putrescinium(2+) and K+ binding. The com­plete polyamine dication is visible in the electron density and assumes a position that allows for hydrogen-bond interactions with three Z-DNA duplexes. The K+ cation occupies a mixed K+/H2O site and forms an irregular coordination sphere interacting with water molecules and the O atoms of two phosphate groups of two Z-DNA molecules, with some of the ligands present at fractional occupancy.

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The rare-earth-element occupancy scheme in A3RE2(BO3)4 (A = Ca, Sr or Ba) structures shows a smooth dependence on the RE to A size ratio.

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The structures of three iodo­chalcones are presented, highlighting the dependence of intermolecular bonding on the functionalization of their aromatic rings.

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Thermal expansion coefficients are calculated for 6201 molecular crystals in the Cambridge Structural Database and the distributions of the values are assessed.


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The incommensurately modulated crystal structure of α′ (O′3)-type sodium cobalt oxide NaxCoO2 (x ∼ 0.78) is reported.

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The crystal structure of the uranyl arsenate mineral hügelite is affected by twinning due to reticular merohedry (diffraction type II). This study documents, apart from the correct description of the unit cell and the nature of the twinning, the possibilities of the JANA2006 program in revealing the real nature of twinning even if using published structural data without the original reflection files.

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The N—H⋯O, H⋯O=P and H⋯O=C angles (X-ray data/neutron normalized) have been studied in nine new [C(O)NH](N)2P(O)-based structures and 204 analogous structures retrieved from the Cambridge Structural Database. Some topics related to geometry and symmetry are addressed.

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The unit-cell parameter and the first temperature-dependent coefficient of thermal expansion values for nine rare earth di-titanates from 25°C to 1550°C were determined via synchrotron powder diffraction with an optical furnace, extending previous studies by 400°C–600°C. The monoclinic to orthorhombic transformation temperature in La2Ti2O7 was accurately determined with both in situ powder X-ray diffraction and in situ neutron powder diffraction, giving a simpler approach to measuring this phase transformation and with higher resolution than existing single-crystal phase transformation studies.

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The field of 1D perovskites is a growing area and has a wide variety of connectivity of octahedra. A new notation is proposed to bring more concise definition to 1D perovskites.

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The crystal structures of three 2-substituted 6,7,8,9-tetra­hydro-11H-pyrido[2,1-b]quinazolin-11-ones (mackinazolinone derivatives) are characterized using X-ray diffraction. Packing analyses and energy framework calculations contribute to the understanding of packing in the crystal and enable the nature of the underlying inter-molecular interactions to be delineated, while additional insight into the isolated compounds is gained from quantum chemical calculations to estimate the effect of the different substituents on the chemical reactivity of mackinazolinone.

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A pseudocubic parameterization of the O4 tetrahedra of quartz and its structural analogue GeO2 at variable temperatures allows direct calculation of tetrahedral tilt angle, the microscopic order parameter of the α↔β phase transition. The crystal structures at interpolated or extrapolated temperatures can also be predicted.

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Short-range and long-range orderings of intercalated Fe atoms in FexTiS2 at the concentrations of 0.05 ≤ x ≤ 0.33 were investigated using scanning transmission electron diffraction and transmission electron diffraction. The measured magnetic properties showed a strong correlation with the ordering of Fe atoms.

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Seleno­urea phase α is stable between 93 and 473 K, but under high-pressure up to 1.0 GPa it reveals three new forms.
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