Crystal structure analysis of a pyrazole carboxylic acid derivative, 5-(trifluoromethyl)-1-phenyl-1H-pyrazole-4-carboxylic acid (1) has been carried out from laboratory powder X-ray diffraction data. The crystal packing in the pyrazole carboxylic acid derivative exhibits an interplay of strong O–H…O, C–H…N and C–H…F hydrogen bonds to generate a three-dimensional molecular packing via the formation of R22(8) and R22(9) rings. Molecular electrostatic potential calculations indicated that carbonyl oxygen, pyrazole nitrogen and fluorine atoms to be the strongest acceptors. The relative contribution of different interactions to the Hirshfeld surface of pyrazole carboxylic acid and a few related structures retrieved from CSD indicates that H…H, N…H and O…H interactions can account for almost 70% of the Hirsfeld surface area in these compounds.

A new polymorph of iodic acid, δ-HIO3, synthesized via aerosol spray pyrolysis was characterized with powder X-ray diffraction and its crystal structure was solved. We find that a previously misidentified phase of I4O9 hydrate is in fact a new polymorph of HIO3, which crystalizes in the orthorhombic space group P212121.

4-hydroxy-3-methoxyphenyl-4-hydroxycoumarin chalcone (C19H14O6) was synthesized by the Claisen–Schmidt reaction with the condensation of 3-acetyl-4-hydroxycoumarin with 4-hydroxy-3-methoxybenzaldehyde (vanillin). The new compound was characterized by Fourier transform infrared microscopy, UV–vis 1H, and 13C NMR spectroscopy and its crystal structure was ab initio determined from laboratory X-ray powder diffraction data. The crystal structure is monoclinic with unit-cell parameters a = 14.3181(4), b = 8.040 71(9), c = 13.5524(3), β = 100.3559(13)°, V = 1534.84(6) Å3, and space group P21/c.

Many N-acylhydrazone derivatives synthetized in LASSBio® cannot be prepared as single crystals of sufficient size and/or quality for structure determination to be carried out using single crystal X-ray diffraction techniques. This article highlights the opportunity for determining crystal structures of this class of compounds directly from powder diffraction data. For this task, the crystal structure of LASSBio-294 was re-determined by means of conventional X-ray powder diffraction data and so, compared with the crystal structure already determined for single crystal data. LASSBio-294 is a cardioactive compound of the N-acylhydrazone class, which can become part of the therapeutic interventions designed to decrease exertional fatigue, and, consequently, improve the quality of life of patients suffering from chronic heart failure. Its final crystal structure was refined by means of the Rietveld method (Rietveld, 1967; 1969). This drug crystallizes in a monoclinic (P21/c) space group, with unit cell parameters a = 11.3413(3) Å, b = 12.3573(4) Å, c = 9.0158(3) Å, β = 89.821(2)°, V = 1263.55(7) Å3, Z = 4, Ź = 1 and ρcalc = 1.4419(1) g cm−3. The goodness-of-fit indicator and R-factors were, respectively: χ2 = 1.203, R Bragg  = 0.696%, R wp  = 5.59%, R exp  = 4.65% and R p  = 4.18%. The molecules in LASSBio-294 are H-bonded along the c-axis involving the atoms N(3)–H(8)···O(4).

The structure determination of an HfSi4 precipitate has been carried out by a combination of two precession electron diffraction techniques: high precession angle, 2.2°, single pattern collection at eight different zone axes and low precession angle, 0.5°, serial collection of patterns obtained by increasing tilts of 1°. A three-dimensional reconstruction of the associated reciprocal space shows an orthorhombic unit cell with parameters a = 11.4 Å, b = 11.8 Å, c = 14.6 Å, and an extinction condition of (hkl) h + k odd. The merged intensities from the high angle precession patterns have been symmetry tested for possible space groups (SG) fulfilling this condition and a best symmetrization residual found at 18% for SG 65 Cmmm. Use of the SIR2011 direct methods program allowed solving the structure with a structure residual of 18%. The precipitate objects of this study were reproducibly found in a newly implemented alloy, designed according to molecular orbital theory.

[Zr2F8(dmso)2(H2O)2], a dehydration product of [ZrF4(dmso)(H2O)2]⋅2H2O, crystallizes in the orthorhombic symmetry [space group Cmca, a=7.8266(3) Å, b=13.5847(5) Å, c=15.6119(6) Å, and Z=4]. The structure, solved ab initio in direct space from X-ray powder diffraction data, is built up from [Zr2F8O4] bipolyhedra formed by edge sharing of [ZrF5O2] pentagonal bipyramids (condensed from isolated [ZrF4O3] pentagonal bipyramids in the precursor). Difficulties associated with a fortuitous hexagonal pseudosymmetry were surmounted. The dmso departure at 220 °C leads to an amorphous phase.

The results from a third structure determination by powder diffractometry (SDPD) round robin are discussed. From the 175 potential participants having downloaded the powder data, nine sent a total of 12 solutions (8 and 4 for samples 1 and 2, respectively, a tetrahydrated calcium tartrate and a lanthanum tungstate). Participants used seven different computer programs for structure solution (ESPOIR, EXPO, FOX, PSSP, SHELXS, SUPERFLIP, and TOPAS), applying Patterson, direct methods, direct space methods, and charge flipping approach. It is concluded that solving a structure from powder data remains a challenge, at least one order of magnitude more difficult than solving a problem with similar complexity from single-crystal data. Nevertheless, a few more steps in the direction of increasing the SDPD rate of success were accomplished since the two previous round robins: this time, not only the computer program developers were successful but also some users. No result was obtained from crystal structure prediction experts.

A new way of incorporating powder diffraction data into a cost function to predict the crystalline structure of inorganic solids is proposed. This approach was applied to the following series of compounds: cubic SrTiO3, tetragonal NaNbO3, TiO2 (anatase), tetragonal CaTiO3, and hexagonal BaTiO3. A tremendous increase in the efficiency of obtaining the correct structure is achieved when a cost function based upon this new approach is applied to these problems.

A melt-spun Mg-1.5%wtCa-6wt%Zn alloy was analyzed by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission electron microscopy. The as-solidified alloy exhibited both spherical matrix precipitates and elongated precipitates at the grain boundaries (grain-boundary films). After heat treatment, the alloy showed faceted precipitates (cuboidal shape), mostly on dislocations. It was found that the observed precipitates are the same compound, Ca2Mg6Zn3. As there was no crystallographic data for this compound in the literature, its crystal structure was investigated by comparison of experimental and simulated selected-area electron-diffraction patterns and high-resolution electron microscopy images. This study indicated that Ca2Mg6Zn3 is a trigonal compound with space group P31c and lattice parameters a = 0.97 nm, c = 1.0 nm.