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Laboratory Powder Diffraction Data (laboratory + powder_diffraction_data)
Selected AbstractsStructures of six industrial benzimidazolone pigments from laboratory powder diffraction dataACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Jacco Van De Streek The crystal structures of six industrially produced benzimidazolone pigments [Pigment Orange 36 (, phase), Pigment Orange 62, Pigment Yellow 151, Pigment Yellow 154 (, phase), Pigment Yellow 181 (, phase) and Pigment Yellow 194] were determined from laboratory X-ray powder diffraction data by means of real-space methods using the programs DASH and MRIA, respectively. Subsequent Rietveld refinements were carried out with TOPAS. The crystal phases correspond to those produced industrially. Additionally, the crystal structures of the non-commercial compound `BIRZIL' (a chloro derivative of Pigment Yellow 194) and of a dimethylsulfoxide solvate of Pigment Yellow 154 were determined by single-crystal structure analyses. All eight crystal structures are different; the six industrial pigments even exhibit five different hydrogen-bond topologies. Apparently, the good application properties of the benzimidazolone pigments are not the result of one specific hydrogen-bonding pattern, but are the result of a combination of efficient molecular packing and strong intermolecular hydrogen bonds. [source] Structure determination of Mg3(OH)5Cl·4H2O (F5 phase) from laboratory powder diffraction data and its impact on the analysis of problematic magnesia floorsACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2007Kunihisa Sugimoto The crystal structure with the idealized formula Mg3(OH)5Cl·4H2O, the so-called F5 phase according to 5Mg(OH)2·MgCl2·8H2O in the system MgCl2,MgO,H2O, has been solved ab initio from high-quality laboratory powder diffraction data at room temperature. The F5 phase is structurally related to 3Mg(OH)2·MgCl2·8H2O (F3 form). The F5 phase consists of infinite triple chains with one Mg(OH)6 and two Mg(OH)4(OH2)2 octahedra as building units intercalated by chlorides, which are partly substituted by disordered hydroxides in the real structure. The F5 phase is of technological importance as the most important binder phase in Sorel cements. Knowledge of the crystal structure enables the full quantitative phase analysis of magnesia cements for the first time, which turns out to be very helpful in the search for possible causes of broken or bleached magnesia floors. Two real-life examples are given. [source] Ezetimibe anhydrate, determined from laboratory powder diffraction dataACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Jürgen Brüning Ezetimibe {systematic name: (3R,4S)-1-(4-fluorophenyl)-3-[(3S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one}, C24H21F2NO3, is used to lower cholesterol levels by inhibiting cholesterol resorption in the human intestine. The crystal structure of ezetimibe anhydrate was solved from laboratory powder diffraction data by means of real-space methods using the program DASH [David et al. (2006). J. Appl. Cryst.39, 910,915]. Subsequent Rietveld refinement with TOPAS Academic [Coelho (2007). TOPAS Academic User Manual. Version 4.1. Coelho Software, Brisbane, Australia] led to a final Rwp value of 8.19% at 1.75,Å resolution. The compound crystallizes in the space group P212121 with one molecule in the asymmetric unit. The molecules are closely packed and two intermolecular hydrogen bonds form an extended hydrogen-bond architecture. [source] K3TaF8 from laboratory X-ray powder dataACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010ubomír Smr The crystal structure of tripotassium octafluoridotantalate, K3TaF8, determined from laboratory powder diffraction data by the simulated annealing method and refined by total energy minimization in the solid state, is built from discrete potassium cations, fluoride anions and monocapped trigonal,prismatic [TaF7]2, ions. All six atoms in the asymmetric unit are in special positions of the P63mc space group: the Ta and one F atom in the 2b (3m) sites, the K and two F atoms in the 6c (m) sites, and one F atom in the 2a (3m) site. The structure consists of face-sharing K6 octahedra with a fluoride anion at the center of each octahedron, forming chains of composition [FK3]2+ running along [001] with isolated [TaF7]2, trigonal prisms in between. The structure of the title compound is different from the reported structure of Na3TaF8 and represents a new structure type. [source] Poly[,-2-aminopyrazine-,2N1:N4 -,-cyanido-copper(I)]: a three-dimensional network from laboratory powder diffraction dataACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2008Silvina Pagola In the title compound, [Cu(CN)(C4H5N3)]n or [Cu(,-CN)(,-PyzNH2)]n (PyzNH2 is 2-aminopyrazine), the CuI center is tetrahedrally coordinated by two cyanide and two PyzNH2 ligands. The CuI,cyano links give rise to [Cu,CN], chains running along the c axis, which are bridged by bidentate PyzNH2 ligands. The three-dimensional framework can be described as being formed by two interpenetrated three-dimensional honeycomb-like networks, both made of 26-membered rings of composition [Cu6(,-CN)2(,-PyzNH2)4]. [source] | ||||||||||