Is there any point in making co-crystals?

Many aspects of co-crystals, including their synthesis, characterization and possible applications, are receiving considerable attention from academia and industry alike. The question is, can this interdisciplinary activity be translated into new fundamental insight and new solid forms of high-value materials with improved performances.

Charge density and optical properties of multicomponent crystals containing active pharmaceutical ingredients or their analogues

This article highlights crystal engineering strategies towards optical materials based on active pharmaceutical molecules.

Structural and energy insights on solid-state complexes with trimethoprim: a combined theoretical and experimental investigation

A new organic salt involving trimethoprim, an active pharmaceutical ingredient (API), is formed and characterized by X-ray diffraction techniques. The two-dimensional ab initio conformational study supported the results obtained from the solid-state survey.

Non-centrosymmetric crystals of new N-benzyl­idene­aniline derivatives as potential materials for non-linear optics

Single crystals of three N-benzylideneaniline derivatives containing electron–push–pull groups have been grown. Two crystallize in non-centrosymmetric space groups with molecular skeletons of high planarity. Quantum-mechanical calculations strengthen the potential non-linear optical application of the compounds obtained.

Intermolecular interactions of proton transfer compounds: synthesis, crystal structure and Hirshfeld surface analysis

The synthesis and structural study of three new proton transfer compounds containing amino acids are reported. Hydrogen bonding and intermolecular interactions are studied by means of the graph-set theory and the Hirshfeld surface analysis.

From a binary salt to salt co-crystals of antibacterial agent lomefloxacin with improved solubility and bioavailability

Ternary salt co-crystals were established by virtue of chemical and geometrical arguments, which give evidence that cocrystallization of multiple active pharmaceutical ingredients (APIs) could improve the solubility and bioavailability of lomefloxacin.

How does binding of imidazole-based inhibitors to heme oxygenase-1 influence their conformation? Insights combining crystal structures and molecular modelling

Single-crystal structures of imidazole-based inhibitors of heme-oxygenase are presented and analysed in-depth. Conformational data from crystallography, quantum mechanics analysis, and from molecular docking are in good agreement.

Anomalous X-ray diffraction study of Pr-substituted BaCeO_3 − δ

The effect of Pr on the crystal structure of BaCe_1 − xPr_xO_3 − δ was studied. Anomalous X-ray diffraction (AXRD) was used to determine the Pr occupancy in Ba and Ce sites. The structural parameters were correlated with H-ionic conductivity and electron transport.

A novel characterization of organic molecular crystal structures for the purpose of crystal engineering

A quantitative method based on the identification of close-packed blocks (CPB) and the junction zones (JZ) between them is used to characterize organic molecular crystal structures. The analytical tools defined, which include two-dimensional packing fractions and molecular-based cells (MBC), allow relationships between molecular shape, substitution patterns and crystal structure to be established.

Crystal structure and phase transition in (NH₄)₃WO₂F₅: from dynamic to static orientational disorder

Cubic (NH₄)₃WO₂F₅ = (NH₄)₃[WO₂F₄]F exhibits a structural phase transition from dynamic to static orientational disorder. Dynamic disorder with the escape of a tungsten atom on the cuboctahedron enables the O and F atoms to be identified on a local scale and determine the real geometry of the cis-WO₂F₄ octahedron.

An alternative empirical model for the relationship between the bond valence and the thermal expansion rate of chemical bonds

The relationship between the bond valence s and the thermal expansion rate of chemical bonds (dr/dT) has been closely approximated using the alternative three-parameter empirical model (dr/dT) = (u + vs)^–1/w, where u, v and w are the refinable parameters.