Crystal growth of zirconium‐doped KTiOPO4 crystals in the K2O‐P2O5‐TiO2‐ZrF4 system

Zirconium‐doped KTiOPO₄ (KTP) crystals were grown using a high temperature flux method in the K₂O‐P₂O₅‐TiO₂‐ZrF₄ system. The dopant content in the single crystals with general composition KTi_1‐xZr_xOPO₄ (where x = 0 – 0.026) strongly depends on zirconium concentration in the homogeneous melts. AES‐ICP method and X‐ray fluorescence analysis were used to determine the composition of the obtained crystals. Phase analyses of the products were performed using the powder XRD. The structures of KTiOPO₄ containing different quantities of Zr were refined on the basis of single crystal XRD data. Applying ZrF₄ precursor for zirconium injection into the flux allowed growing the zirconium‐doped KTP crystals at 930–750°C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Two pseudo‐enantiomeric forms of N‐benzyl‐4‐hydroxy‐1‐methyl‐2,2‐dioxo‐1H‐2λ6,1‐benzothiazine‐3‐carboxamide and their analgesic properties

The fact that molecular crystals exist as different polymorphic modifications and the identification of as many polymorphs as possible are important considerations for the pharmaceutic industry. The molecule of N‐benzyl‐4‐hydroxy‐1‐methyl‐2,2‐dioxo‐1H‐2λ⁶,1‐benzothiazine‐3‐carboxamide, C₁₇H₁₆N₂O₄S, does not contain a stereogenic atom, but intramolecular hydrogen‐bonding interactions engender enantiomeric chiral conformations as a labile racemic mixture. The title compound crystallized in a solvent‐dependent single chiral conformation within one of two conformationally polymorphic P2₁2₁2₁ orthorhombic chiral crystals (denoted forms A and B). Each of these pseudo‐enantiomorphic crystals contains one of two pseudo‐enantiomeric diastereomers. Form A was obtained from methylene chloride and form B can be crystallized from N,N‐dimethylformamide, ethanol, ethyl acetate or xylene. Pharmacological studies with solid–particulate suspensions have shown that crystalline form A exhibits an almost fourfold higher antinociceptive activity compared to form B.     

Fracture toughness and crystallographic characteristics of Li6GdB3O9 single crystals

Characteristics of the structure of single crystals of binary lithium-gadolinium borate Li₆GdB₃O₉ with mixed-type bonding (ionic and covalent) are studied. The system of cleavage planes in Li₆GdB₃O₉ single crystals is associated with the break of the Gd-O bridging bonds and the longest Li-O bonds in the Li five-vertex polyhedra. The fracture toughness in the cleavage planes is determined by microindentation. It is shown that the character of resistance to deformation and fracture toughness are determined by the orientation of the cleavage planes with respect to the faces where boron-oxygen triangles with directional covalent bonds are located.     

Roman Coarse Ware from Bavaria, Austria and Northern Italy

This interdisciplinary study focuses on a specific type of Roman coarse ware that was widely distributed in Bavaria, Austria and northern Italy during the 1st half of the 1st century AD. Various physical methods were applied to study the provenance of this characteristic marble tempered blackware and to assess its production techniques. The blackware found in large numbers on the Auerberg and at other sites in southern Germany can be identified as imported from East Tyrol, Austria.     

Two polymorphs of 2‐(4‐chlorophenyl)‐4‐methylchromenium perchlorate

Crystallization (from ethyl acetate solution) of 2‐(4‐chlorophenyl)‐4‐methylchromenium perchlorate, C₁₆H₁₂ClO⁺·;ClO₄⁻, (I), yields two monoclinic polymorphs with the space groups P2₁/n [polymorph (Ia)] and P2₁/c [polymorph (Ib)]; in both cases, Z = 4. Cations and anions, disordered in polymorph (Ib), form ion pairs in both polymorphs as a result of Cl—O...π interactions. Related by a centre of symmetry, neighbouring ion pairs in polymorph (Ia) are linked viaπ–π interactions between cationic fragments, and the resulting dimers are linked through a network of C—H...O(perchlorate) interactions between adjacent cations and anions. The ion pairs in polymorph (Ib), arranged in pairs of columns along the a axis, are linked through a network of C—H...O(perchlorate), C—Cl...π, π–π and C—Cl...O(perchlorate) interactions. The aromatic skeletons in polymorph (Ia) are parallel in the cationic fragments involved in dimers, but nonparallel in adjacent ion pairs not constituting dimers. In polymorph (Ib), these skeletons are parallel in pairs of columns, but nonparallel in adjacent pairs of columns; this is visible as a herring‐bone pattern. Differences in the crystal structures of the polymorphs are most probably the cause of their different colours.     

A crystal structure of mixed-metal dianionic phosphate Cs3.70Mg0.60Ti2.78(TiO)3(P2O7)4(PO4)2

The single crystals of caesium magnesium titanium (IV) tri-oxo-tetrakis-diphosphate bis-monophosphate, Cs_3.70Mg_0.60Ti_2.78(TiO)₃(P₂O₇)₄(PO₄)₂, crystallize in sp. gr. P-1 (No. 2) with cell parameters a=6.3245(4), b=9.5470(4), c=15.1892(9) Å, α=72.760(4), β=85.689(5), γ=73.717(4), z=1. The titled compound possesses a three-dimensional tunnel structure built by the corner-sharing of distorted [TiO₆] octahedra, [Ti₂O₁₁] bioctahedra, [PO₄] monophosphate and [P₂O₇] pyrophosphate groups. The Cs⁺ cations are located in the tunnels. The partial substitution of Ti positions with Mg atoms is observed. The negative charge of the framework is balanced by Cs cations and Mg atoms leading to pronounced concurrency and orientation disorder in the [P₂O₇] groups, which coordinate both.     

Synthesis of 1-[1-bromo-2-benzoyl(2-thenoyl)vinyl]-1,1-dimethylhydrazinium bromides from 1-bromo-2-benzoyl(2-thenoyl)acetylenes and 1,1-dimethylhydrazine

1-[1-Bromo-2-benzoyl(2-thenoyl)vinyl]-1,1-dimethylhydrazinium bromides were synthesized by the reactions of 1-aroyl-2-bromoacetylenes withN,N-dimethylhydrazine in acetonitrile at 20°C. The structure of 1-(2-benzoyl-1-bromovinyl)-1,1-dimethylhydrazinium bromide was established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1536–1538, August, 1999.     

Synthesis, characterization and crystal structure of K2Bi(PO4)(MoO4)

A new potassium bismuth phosphate-molybdate K₂Bi(PO₄)(MoO₄) has been synthesized by the flux method and characterized by single-crystal and powder X-ray diffraction, IR spectroscopic studies. The compound crystallizes in the orthorhombic system with the space group Ibca and the cell parameters: a=19.7037(10), b=12.4752(10), c=7.0261(10). This phase exhibits an original layered structure, in which the [Bi(PO₄)(MoO₄)]_∞ layers consist of [Bi₂Mo₂O₁₈]_∞ chains linked through single PO₄ tetrahedra. The K⁺ cations interleaved between these layers exhibit a monocapped distorted cubic coordination.     

Crystal and molecular structure of β-cyclodextrin inclusion complex with succinic acid

The crystal complex of β-cyclodextrin with succinic acid, intermediate product of hydrolysis reaction of succinic anhydride in the presence of β-cyclodextrin, was isolated and studied by X-ray analysis (monoclinic, space group P2₁, a = 15.1977(7) Å, b = 10.1763(5) Å, c = 20.6943(6) Å, β = 109.239(4)°, V = 3021.8(2) Å³, Z = 2, R ₁ = 0.0359, wR ₂ = 0.0947). It was proved that β-cyclodextrin and succinic acid form an inclusion complex, which exists in crystal state as a heptahydrate. The molecule of succinic acid is fully included in the β-cyclodextrin cavity with its carboxyl groups accessible for water molecules. Water molecules located at borders of cavity rims and in interstices between molecules of β-cyclodextrin participate in formation of intermolecular hydrogen bonds. The overall structure does not contain disordered fragments. The crystal conformation of succinic acid corresponds to one of possible conformers of the molecule in vacuo and is almost not disturbed by intermolecular interactions in crystal. Based on the analysis of structural features of the crystal conformation of succinic acid and character of its location in the β-cyclodextrin cavity, it was suggested that hydrolysis of succinic anhydride via ring opening and formation of succinic acid is mediated by cyclodextrin microenvironment and it likely occurs near the narrow rim of the macrocycle cavity.