The Na—O bond in sodium fenamate

The polymeric structure of sodium di­aqua­fenamate–water (1/1) is investigated and the theoretical analysis reveals that the Na—O bonds are very weak, comparable with the weak N—H⋯O intramolecular hydrogen bond. The polymeric structure is stabilized by the interaction of the sodium cation with the surrounding water molecules.

Stimuli-responsive aggregation-induced fluorescence in a series of bi­phenyl-based Knoevenagel products: effects of substituent active methyl­ene groups on π–π interactions

A photophysical study involving three bi­phenyl-based Knoevenagel products has been carried out. Two of the compounds show stimuli-responsive aggregation-enhanced emission. Photophysical behavior of the active fluoro­phore is explained based on molecular packing and π–π interactions.

The effective volumes of waters of crystallization: non-ionic pharmaceutical systems

The effective volumes of waters of crystallization have been determined for 27 hydrate/parent systems, with a median value of 22.8 ų. These results may be helpful in assessing and predicting hydrate crystal structures.

Analytical description of nanowires. I. Regular cross sections for zincblende and diamond structures

Regular cross sections of zincblende- and diamond-structured nanowires (NWires) are described, and number series are presented for NWire atoms, for the bonds between these and for the NWire interface bonds for a slab of unit-cell length along the NWire axis, as well as the characteristic lengths and areas of the NWire cross sections. The ratios of internal bonds per NWire atom, of internal to interface bonds and of interface bonds per NWire atom present fundamental tools to interpret any spectroscopic data which depend on the diameter and cross-sectional shape of NWires.

Understanding the formation of apremilast cocrystals

In investigating the formation of apremilast cocrystals, this work demonstrates the preference for aromatic–aromatic interactions over hydrogen bonds in the studied crystals and the stabilizing role of disorder, leading to entropy-driven formation of the cocrystals.

Octahedral tilting in the polar hexagonal tungsten bronzes RbNbW₂O₉ and KNbW₂O₉

The first powder neutron diffraction study of the hexagonal tungsten bronzes RbNbW₂O₉ and KNbW₂O₉ is presented. The existence of octahedral tilting that has not been previously observed using X-ray diffraction is also reported.

A commensurately modulated crystal structure and the physical properties of a novel polymorph of the caesium manganese phosphate CsMnPO₄

A new modification of CsMnPO4 (β-phase) is discussed in a superspace approach. Structural relations with topologically and chemically similar compounds are shown.

Pristine and hydrated fluoroapatite (0001)

The surface structure of fluoro­apatite (0001) under dry and humid conditions has been probed with X-ray diffraction. The dry surface shows incomplete tetrahedra on the surface that are partially filled when the surface is hydrated.

Solvatochromism and mechanochromism observed in a tri­phenyl­amine derivative

Multi-fluorescent properties of a tri­phenyl­amine derivative are investigated under different conditions.

Insight into the role of pre-assembly and desolvation in crystal nucleation: a case of p-nitro­benzoic acid

The pathway and hybrid control mechanism of crystal nucleation were studied through both experimental and computational investigation on the role of pre-assembly and desolvation in the nucleation process.

Lanthanide coordination polymers based on designed bifunctional 2-(2,2′:6′,2″-terpyridin-4′-yl)benzene­sulfonate ligand: syntheses, structural diversity and highly tunable emission

Seven novel lanthanide coordination polymers were prepared. These coordination polymers exhibit several 2D and 3D framework topologies that are dictated by the choice of metal salts and carboxyl­ate ligands. The heteronuclear compounds [Eu_xTb_1−x(STP)(1,2-bdc)]_n [STP⁻ is 2-(2,2′:6′,2′′-terpyridin-4′-yl)benzenesulfonate and (1,2-bdc)²⁻ is benzene-1,2-dicarboxylate] (0 ≤ x ≤ 1) have potential use as efficient luminescent tags.

The shortest chalcogen⋯halogen contacts in molecular crystals

An analysis of chalcogen–halogen interactions based on structures deposited in the Cambridge Structural Database is presented.

The crystal structure and phase stability of the zeta phase in the group VB transition metal carbides: a computational investigation

Using density functional theory, the structure, stability and properties of the zeta phase in the group VB transition metal carbides are examined. It is concretely shown that this phase occurs at the composition M₃C₂ (M = Ta, Nb, V). The three systems share a crystal structure, but they exhibit differences in how the phase accommodates non-stoichometry, which has implications for their material properties.

Crystal structure, vibrational spectroscopy and optical properties of a one-dimensional organic–inorganic hybrid perovskite of [NH₃CH₂CH(NH₃)CH₂]BiCl₅

Optical properties and crystal structure of organic–inorganic hybrid perovskite [NH₃CH₂CH(NH₃)CH₃]BiCl₅ (determined using single-crystal X-ray diffraction) are presented. The title compound crystallizes in the orthorhombic noncentrosymmetric space group Pca2₁ with eight molecules per unit cell.

Influence of ortho-substituent on the molecular and crystal structures of 2-(N-aryl­imino)­coumarin-3-carboxamide: isotypic and polymorphic structures

A series of substituted 2-(N-aryl­imino)­coumarin-3-carboxamides is divided into three groups of isotypic crystal structures with different molecular structure and crystal organization.

Rb₂CaCu₆(PO₄)₄O₂, a novel oxophosphate with a shchurovskyite-type topology: synthesis, structure, magnetic properties and crystal chemistry of rubidium copper phosphates

A novel compound, Rb₂CaCu₆(PO₄)₄O₂, was synthesized by a hydrothermal method and characterized as the shchurovskyite-type structure, based upon a heteropolyhedral copper phosphate framework. Microscopic calculations are indicative of possible low-dimensional magnetic behavior, as they confirm weak magnetic coupling between the copper-based layers mediated by the Cu–Cu pairs.

Co-crystals. Preparation, Characterization and Applications