Lab in a DAC – high-pressure crystallography as a powerful tool to study chemical interactions and chemical reactions

High-pressure X-ray diffraction was first used to find and solve the structures of high-pressure polymorphs. The challenge today is to find some universal laws and rules of high-pressure transformations and Katrusiak [Acta Cryst. (2019), B75, 918–926] suggests such possible laws and rules.

Lab in a DAC – high-pressure crystal chemistry in a diamond-anvil cell

For 60 years innovative methods using the diamond-anvil cell (DAC) have been applied in high-pressure crystal chemistry, physics and biology in increasingly many laboratories.

Atomic atmosphere: a way to understand phase evolution during vanadium slag roasting at the atomic level

The concept of `atomic atmosphere' is proposed, which includes chemical state, chemical and spatial environments, to uncover the atomic level reaction mechanism of crystal-involved solid reactions.

Polymorphic forms of bendamustine hydro­chloride: crystal structure, thermal properties and stability at ambient conditions

Different polymorphic forms of bendamustine hydrochloride, a chemotherapy medication used in the treatment of chronic lymphocytic leukaemia, non-Hodgkin's lymphoma and multiple myeloma, have been found and their relative stabilities established. For three out of the four polymorphs found, the crystalline structures were determined using SC-XRD.

Experimental and theoretical charge density, intermolecular interactions and electrostatic properties of metronidazole

A detailed investigation is presented of the experimental and theoretical charge density and electrostatic properties of the metronidazole molecule. The topological properties of electron density reveal the charge-density distribution of the molecule and non-bonding regions.

Crystal structure and structural phase transition in bis­muth-containing HoFe₃(BO₃)₄ in the temperature range 11–500 K

An accurate X-ray diffraction study of (Ho_0.96Bi_0.04)Fe₃(BO₃)₄ single crystals in the temperature range 11–500 K has been performed on a laboratory diffractometer and using synchrotron radiation. A structural phase transition at about 365 K has been studied.

Agomelatine–hydro­quinone (1:1) cocrystal: novel polymorphs and their thermodynamic relationship

A new polymorph of agomelatine–hydro­quinone cocrystal (form IV) was identified as the most stable polymorph at room temperature by thermal, slurry and solubility experiments.

Phase transitions in Bi₄Ti₃O₁₂

A Landau-type phase diagram describing the temperature phase transitions in the layered perovskite ferroelectric Bi₄Ti₃O₁₂ is constructed.

Polymorphs of 2,4,6-tris­(4-pyridyl)-1,3,5-triazine and their mechanical properties

A new crystalline phase of the crystal sponge ligand 2,4,6-tris­(4-pyridyl)-1,3,5-triazine was obtained as long needles showing elastic bending behaviour, in contrast with the known phase which is brittle under mechanical force.

Hardening tungsten carbide by alloying elements with high work function

Alloying elements with high work functions can increase the electron density of WC and strengthen its bonds, leading to higher hardness. A new type of Re-alloyed tungsten carbide with remarkably increased high hardness was synthesized for the first time.

Structural, theoretic and spectroscopic analysis of 2-methyl-5-nitro­aniline salts with various inorganic acids

Hydrogen-bonding patterns of six 2-methyl-5-nitro­anilinium salts are analysed using the graph-set approach and mathematical relations among graph-set descriptors are presented. Conformation of the H2Me5NA⁺ cation is characterized by quantum chemical calculations and the strength of hydrogen bonds is analysed using IR spectroscopy.

How hard metal becomes soft: crystallographic analysis on the mechanical behavior of ultra-coarse cemented carbide

Based on the designed experiments and microstructural characterization combined with crystallographic analysis, the evolution of slip systems, motion and interaction of dislocations with temperature are quantified for the WC hard phase. Mechanisms are proposed for the formation of the sessile dislocations in the main slip systems at the room temperature and the glissile dislocations in the new slip systems activated at high temperatures.

The first- and second-order isothermal phase transitions in Fe₃Ga-type compounds

Structural features and kinetics of the transition between ordered metastable b.c.c.-derived D0₃ and equilibrium f.c.c.-derived L1₂ phases of Fe–xGa alloys (x = 27.2% and 28.0%) during isothermal annealing are analyzed.

Effect of pressure on the order–disorder phase transitions of B cations in AB′_1/2B′′_1/2O₃ perovskites

The effect of pressure on the order–disorder phase transitions of the B cations in AB′_1/2B′′_1/2O₃ perovskites is studied theoretically and estimates are made for certain compositions. In many cases pressure can significantly increase or decrease the order–disorder transition temperature, which provides another way of manipulating cation ordering.

Thermomechanical, electronic and thermodynamic properties of ZnS cubic polymorphs: an ab initio investigation on the zinc-blende–rock-salt phase transition

A theoretical DFT investigation of the thermomechanical properties and phase boundary between zinc-blende and rock-salt ZnS polymorphs between 0 and 25 GPa and 0 and 800 K is reported.

Two topologically different 3D Cu^II metal–organic frameworks assembled from the same ligands: control of reaction conditions

Two 3D Cu^II metal–organic frameworks were assembled from 2,2′-di­sulfonylbi­phenyl-4,4′-di­carb­oxy­lic acid and 4,4′-bi­pyridine; one compound shows an unprecedented trinodal 4,4,5-connected topology and the other a 4,6-connected network with the fsc topology.

Hodgesmithite, (Cu,Zn)₆Zn(SO₄)₂(OH)₁₀·3H₂O, a new copper zinc sulfate mineral with a unique, decorated, interrupted-sheet structure

The crystal structure of the new mineral hodgesmithite has been solved using synchrotron radiation. The structure contains a unique, decorated, interrupted sheet which is capped by ZnO₄ and SO₄ tetrahedra.

Highly luminescent crystals of a novel linear π-conjugated thio­phene–phenyl­ene co-oligomer with a benzo­thia­diazole fragment

The synthesis, growth from solutions, structure and photoluminescence of crystals of a new linear thio­phene-phenyl­ene co-oligomer (TMS-2T-Ph)₂-BTD with a central benzo­thia­diazole fragment within the conjugated core are presented.

Three-dimensional morphology of anatase nanocrystals obtained from supercritical flow synthesis with industrial grade TiOSO₄ precursor

Anatase nanocrystals are synthesized from industrial grade titanyl sulfate precursor in a supercritical flow reactor and their crystal morphology is extensively characterized using powder X-ray diffraction, transmission electron microscopy and Raman spectroscopy.

Automated oxidation-state assignment for metal sites in coordination complexes in the Cambridge Structural Database

A procedure is described for the automated assignment of oxidation states of transition metals in coordination complexes in the Cambridge Structural Database.

Solvates of acoti­amide hydro­chloride: characterization and phase transformation

Five novel crystal structures of acoti­amide hydro­chloride with different solvates were determined. Phase transformation experiments show that a humidity-induced phase transformation is closely tied to moisture content.

Fluxional seven-coordinated fluorido- and oxo­fluoridotantalates

The highly disordered crystal structure of Rb₃TaOF₆ with the coexistence of rigid and fluxional pentagonal bipyramidal polyhedra is evidenced using vibrational spectra. The existence of synchronous stretching vibration of the Ta—O and Ta—F bonds in the region of 700–800 cm⁻¹.

Structural elucidation of triclinic and monoclinic SFCA-III – killing two birds with one stone

Synthesis experiments in the system CaO–SiO₂–Al₂O₃–Fe₂O₃–MgO resulting in the formation of SFCA-III are reported. SFCA-III is a new n = 2 member of a polysomatic series of M_14+6nO_20+8n compounds based on pyroxene-spinel modules which are of relevance to iron-ore sintering. Single-crystal diffraction studies using synchrotron radiation revealed that the compound occurs in two polytypes representing maximum degree of order structures which explains the observed allotwinning of the sample.

Incommensurately modulated crystal structure of flamite – natural analogue of -Ca₂SiO₄

The incommensurately modulated crystal structure of flamite, a natural analogue of the high-temperature modification of Ca₂SiO₄, is described.

The structures and phase transitions in 4-amino­pyridinium tetra­aqua­bis­(sulfato)­iron(III), (C₅H₇N₂)[Fe^III(H₂O)₄(SO₄)₂]

A detailed investigation is reported of three successive structural phase transitions from a disordered room-temperature phase through two incommensurately modulated structures to a completely ordered twinned low-temperature phase in the organic–inorganic hybrid compound (C₅H₇N₂)[Fe^III(H₂O)₄(SO₄)₂].

Combining photoinduced linkage isomerism and nonlinear optical properties in ruthenium nitro­syl complexes

Double optical functionality of a ruthenium nitro­syl compound is achieved by the combination of photoswitching of the nitro­syl ligands, giving rise to photochromic behaviour, with the second-harmonic generation enabled by the alignment of the molecular dipoles in the non-centrosymmetric structure of trans-[RuNO(NH₃)₄F]SiF₆.

Ammonium tantalum oxide fluorides: new features of dynamic disorder

An eight-coordinated tantalum polyhedron in the shape of a cube with one vacant vertex is discovered for the first time in the dynamically disordered crystal structure of a tantalum fluoride double salt containing some oxygen.

Chain caesium borophosphates with B:P ratio 1:2: synthesis, structure relationships and low-temperature thermodynamic properties

The crystal structures of three novel caesium borophosphates with chain-type anionic fragments are reported. Relationships between new and known phases are discussed in terms of the effect of the initial crystallization medium on the structure.

Comparison of the crystal structures and physicochemical properties of novel resveratrol cocrystals

Resveratrol (RSV) cocrystallizes with 4,4′-vinyl­enedi­pyridine (DPE) to form five cocrystals including solvates and polymorphs. The RSV–2DPE can transform from form I to form II during the heating process, retaining their single crystal forms. The physicochemical properties of RSV cocrystals are closely related to their crystal packing modes. The cocrystallization with DPE or 4,4′-ethyl­enedi­pyridine (BPE) modulates the RSV solubility and dissolution.

Inter­molecular inter­action energies and molecular conformations in N-substituted 4-aryl-2-methyl­imidazoles with promising in vitro anti­fungal activity

An efficient and regioselective microwave-assisted synthesis of tri-substituted imidazoles is presented. Crystallographic results show a correlation between substituent groups, molecular conformation and supramolecular assembly, with the energy frameworks dominated by dispersion forces. N-Substituted imidazoles were tested against standardized strains of the clinically important fungi Candida albicans and Cryptococcus neoformans, displaying good activities against C. neoformans.

Group-theoretical analysis of structural instability, vacancy ordering and magnetic transitions in the system troilite (FeS)–pyrrhotite (Fe_1−xS)

A group-theoretical framework to describe vacancy ordering and magnetism in the Fe_1−xS system is developed.

Intermetallics. Synthesis, Structure, Function. Second edition

Crystal Growth for Beginners. Fundamentals of Nucleation, Crystal Growth and Epitaxy