The continuing development and expansion of Acta Crystallographica Section B

The editorial describes the latest developments on the journal and plans for the future.

The ecstasy and the agony; compression studies of 3,4-methylene­dioxymethamphetamine (MDMA)

This study investigates the compression of the illicit material MDMA or `ecstasy'.

Charge density investigations on [2,2]-para­cyclophane – in data we trust

Interest in the reactivity and phase transition of the molecule makes [2,2]-paracyclophane a rewarding benchmark system for charge density investigations and at the same time a showcase for various data quality issues.

(C₄H₁₂N₂)[CoCl₄]: tetrahedrally coordinated Co²⁺ without the orbital degeneracy

The paper describes the synthesis and characterization of a low-dimensional magnet based on tetrahedrally coordinated Co²⁺ ions. Results show the absence of any spin-orbit coupling and orbital degeneracy present in both octahedral and often tetrahedral environments.

Solid-state supramolecular architecture of carben­oxolone – comparative studies with glycyrrhetinic and glycyrrhizic acids

Three closely related triterpene-based molecules aggregate from layers consisting of a hydrophobic interior and surfaces covered by different hydrophilic head groups.

Charge distribution as a tool to investigate structural details. III. Extension to description in terms of anion-centred polyhedra

The charge distribution method is generalized to anion-centred coordination polyhedra and the advantages of this description of some crystal structures are presented.

The square-planar to flattened-tetrahedral CuX₄²⁻ (X = Cl, Br) structural phase transition in 1,2,6-tri­methylpyridinium salts

Each (1,2,6-trimethylpyridinium)₂CuX₄ (X = Cl, Br) compound exhibits a structural phase transition in which the isolated complex anion geometry transforms from square-planar to flattened-tetrahedral (at 323 K for Cl, 225 K for Br), contrary to traditional expectations that such transitions only occur in chloride salts (as green-to-yellow thermochromism) in the presence of strong N—H hydrogen bonding.

Structural investigations in BaFe_2 − xRu_xAs₂ as a function of Ru and temperature

Synchrotron X-ray diffraction measurements on BaFe_1.9Ru_0.1As₂ single crystals were performed at different temperatures across the spin-density wave/structural transition. A clear anomaly in the c-axis, As—Fe—As bond angle and Fe—As bond lengths has been observed close to the structural transition. These anomalies in structural parameters are analysed using ab initio electronic structure calculations

Calcium tartrate esahydrate, CaC₄H₄O₆·6H₂O: a structural and spectroscopic study

The crystal structure of calcium tartrate esahydrate, CaC₄H₄O₆·6H₂O, has been solved from single-crystal X-ray diffraction data and refined in space group P2₁2₁2. Micro-Raman and FT–IR spectroscopic data are also provided.

Crystal structure of magnesium dichloride decahydrate determined by X-ray and neutron diffraction under high pressure

The previously unknown form of the magnesium dichloride hydrate series, MgCl₂·10H₂O, is discovered under high pressure. The structures of this newly found compound and its deuterated counterpart are solved by in-situ powder synchrotron X-ray and spallation neutron diffraction.

Structure of Pb-rich chabournéite from Jas Roux, France

This study investigates the real crystal structure of the thallium sulfosalt chabournéite, comparing it with the closely related homeotypes dalnegroite and protochabournéite

Structure of Pigment Yellow 181 di­methylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate from XRPD + DFT-D

The relatively complex structure of a triclinic disolvate was solved from low-resolution laboratory powder diffraction data through the intermediate use of dummy atoms and the combination with quantum-mechanical calculations.

In-situ laser synthesis of Nd–Al–O coatings: the role of sublattice cations in eutectic formation

The in-situ laser formation of the NdAlO₃/NdAl₁₁O₁₈ eutectic suggests that the eutectic formation needs a degree of continuity within the cation arrays of its components. These structure sublattices may be an essential driving force behind the eutectic formation.

Entrance and diffusion pathway of CO₂ and di­methyl ether in silicalite-1 zeolite channels as determined by single-crystal XRD structural analysis

Adsorption pathways in MFI-type zeolite channels were investigated by a selective sealing method. CO₂ enters mainly into the straight channel mouths and diffuses, and dimethyl ether enters mainly into the sinusoidal channel mouths and diffuses.

A new polymorph of 1-hy­droxy-2-naphthoic acid obtained during failed co-crystallization experiments

A new polymorph of 1-hydroxy-2-naphthoic acid was synthesized and structurally elucidated by single-crystal structure analysis. Physical and thermal properties were evaluated by a variety of analytical techniques.

Phase Transitions in Materials

Acronyms and Abbreviations in Natural Sciences and Technology