Structural investigation of GeSb₆Te₁₀ and GeBi₆Te₁₀ intermetallic compounds in the chalcogenide homologous series

The GeSb₆Te₁₀ and GeBi₆Te₁₀ intermetallic compounds have 51-layered cubic close-packed stacking structures in common. In these structures the Ge/Sb (Ge/Bi) and Te layers are stacked alternately; Te atoms exclusively occupy their own specific layers, whereas Ge and Sb (Bi) atoms are randomly located at the other layers, causing a partially disordered atomic occupation in these layers.

Polymorphism and piezochromicity in the three-dimensional network-based phosphate RbCuPO₄

Polymorphism and piezochromicity are reported at room temperature in the three-dimensional network-based phosphate RbCuPO₄, generated by subtle interplay between copper and phosphate coordination polyhedra. A combination of formula-unit volume reduction and conversion of copper dimer to trimer chains accompanied by changes in the copper coordination number are shown to be responsible for the piezochromicity.

Orientational ordering, tilting and lone-pair activity in the perovskite methylammonium tin bromide, CH₃NH₃SnBr₃

The structure of the 215 K phase of methylammonium tin bromide is solved, and interplay between hydrogen bonding and lone-pair distortions is examined.

On the sequence of three related phases of [Ni(H₂O)₂(15-crown-5)](HSO₄)₂ in the temperature range 110–295 K

The compound [Ni(H₂O)₂(15-crown-5)](HSO₄)₂ is remarkable for having two non-destructive solid–solid phase transitions in the temperature range 110−295 K. Three related phases [room-, intermediate- and low-temperatures phases (I), (II) and (III)] have been isolated; all phases have similar packing but the Z′ number varies in the sequence (I) ↔ (II) ↔ (III).

Syntheses, spectroscopic study and X-ray crystallography of some new phosphoramidates and lanthanide(III) complexes of N-(4-nitro­benzoyl)-N′,N′′-bis­(morpholino)phosphoric tri­amide

New phosphoramidate compounds have been synthesized and structurally characterized. Their crystal structures reveal that the —C(O)NHP(O)< skeleton shows the syn conformation, in contrast to all similar phosphoro-azo compounds previously reported. The capability for coordinating Ln^III ions have been demonstrated and the corresponding complexes have been obtained.

Structural polymorphism of pyrazinium hydrogen sulfate: extending chemistry of the pyrazinium salts with small anions

Pyrazinium hydrogen sulfate is studied as a candidate for a novel ferroelectric material with giant spontaneous polarization.

Pressure-induced phase transitions in L-alanine, revisited

No pressure-induced polymorphic transitions in L-alanine could be detected by single-crystal and powder X-ray diffraction at least up to ∼ 12 GPa, although some important changes in the intermolecular interactions occur, which also manifest themselves in the Raman spectra. Two new phases (presumably solvates) of L-alanine could be crystallized from MeOH/EtOH/H₂O solution in the pressure range 0.8–4.7 GPa, but only if the sample was kept at these pressures for at least 1–2 d, and converted back to L-alanine on reverse decompression.

Structures of alkyl-substituted Tröger's base derivatives illustrate the importance of Z′ for packing in the absence of strong crystal synthons

Crystal structures of alkyl-substituted Tröger's base analogues appear to have a tendency for crystallizing in high-Z′ structures. The reasons for this are expanded upon.

An experimental charge density of HEPES

The common organic buffer HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid] used widely in biological research has been studied by high-resolution X-ray single-crystal diffraction. An analysis applying the Hansen–Coppens multipole model and Bader's Quantum-Theory-of-Atoms-in-Molecules (QTAIM) yields an accurate description of the electron density distribution in the crystal.