Crystallographic searches for weak interactions – the limitations of data mining

Identification of weak non-covalent interactions by crystallographic searches in databases such as the Cambridge Structural Database can be misleading, if they are based on an indiscriminate use of all kinds of data; this is also a common problem mining data. An alternative is the use of selected compounds as the database, for which chemistry provides many options.

Jinshajiangite: structure, twinning and pseudo­symmetry

The crystal structure of jinshajiangite is revisited and corrected, with its pseudo-merohedral twinning and pseudosymmetry discussed in detail.

Vanadium clusters formation in geometrically frustrated spinel oxide AlV₂O₄

A theory of the structural phase transition in AlV₂O₄ is proposed.

Control of crystal structure using temperature and time

Presented here are three novel crystal structures [FeC₁₂H₁₂NO₇]·CH₃CN, FeC₁₂H₁₀NO₆ and [FeC₁₂H₁₀NO₆]₄ which were obtained using the same starting materials but with the reaction conditions of time and temperature varied.

Nollmotzite, Mg[U^V(U^VIO₂)₂O₄F₃]·4H₂O, the first natural uranium oxide containing fluorine

The twinned structure of the new uranium oxide mineral was refined from X-ray diffraction data and was found to contain fluorine and pentavalent uranium. The presence of pentavalent uranium is indicative of the reducing conditions under which the mineral formed. Nollmotzite is the first naturally occurring uranium oxide mineral that contains fluorine.

(Al,Mg)₃La: a new phase in the Mg–Al–La system

A new intermetallic phase has been identified in the Mg–Al–La system with the composition of (Al,Mg)₃La. The crystal structure of this phase [C222₁, a = 4.3365 (1), b = 18.8674 (4) and c = 4.4242 (1) Å] has been resolved using high-resolution synchrotron X-ray powder diffraction and verified by high-angle annular dark-field scanning transmission electron microscopy imaging.

Similarities and differences in the crystal packing of halogen-substituted indole derivatives

The crystal structures of newly synthesized halogenated indoles bring out the essential similarity and differences in intermolecular interactions in the solid state. The roles of N—H⋯π and C—H⋯π interactions establish the key role of such interactions in modulating the crystal packing; their significance is established from both energetics from the PIXEL method and topological analysis of the electron density from quantum theory of atoms in molecules (QTAIM).

High-density HNIW/TNT cocrystal synthesized using a green chemical method

HNIW/TNT cocrystals are synthesized by a new chemical method. The performance of the cocrystals is improved from previous preparation techniques and this new method is a more environmentally friendly approach.

Compositionally induced phase transitions and symmetry relations between space groups in the layered system FeIn_1−xY_xGe₂O₇

Symmetry relations between space groups for an arrangement before and after a transition in the thortveitite structure were used to build structural models for compositionally induced phase transitions.