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Sample records for crystal structure mol-ecules

  1. Crystal structure of a 2:1 piroxicam-gentisic acid co-crystal featuring neutral and zwitterionic piroxicam mol-ecules.

    Science.gov (United States)

    Horstman, Elizabeth M; Bertke, Jeffery A; Woods, Toby J; Kenis, Paul J A

    2016-12-01

    A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hy-droxy-1,1-dioxo-N-(pyridin-2-yl)-2H-1λ(6),2-benzo-thia-zine-3-carboxamide-2-(4-oxido-1,1-dioxo-2H-1λ(6),2-benzo-thia-zine-3-amido)-pyridin-1-ium-2,5-di-hydroxy-benzoic acid, 2C15H13N3O4S·C7H6O4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam mol-ecule is in its neutral form and an intra-molecular O-H⋯O hydrogen bond is observed. The other piroxicam mol-ecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intra-molecular N-H⋯O hydrogen bonds occur. The gentisic acid mol-ecule shows whole-mol-ecule disorder over two sets of sites in a 0.809 (2):0.191 (2) ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in the ab plane.

  2. Crystal structure of cis-bis-{4-phenyl-1-[(3R)-1,7,7-tri-methyl-2-oxobi-cyclo-[2.2.1]heptan-3-ylidene]thio-semicarbazidato-κ(3) O,N (1),S}cadmium(II) with an unknown solvent mol-ecule.

    Science.gov (United States)

    Nogueira, Vanessa Senna; Bresolin, Leandro; Näther, Christian; Jess, Inke; de Oliveira, Adriano Bof

    2015-12-01

    The reaction between the racemic mixture of the camphor-4-phenyl-thio-semicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C17H20N3OS)2]. The Cd(II) ion is six-coordinated in a distorted octa-hedral environment by two deprotonated thio-semicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the mol-ecules are connected via pairs of N-H⋯S and C-H⋯S inter-actions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent mol-ecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information.

  3. Crystal structure of 5-amino-5'-chloro-6-(4-chloro-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvent mol-ecule.

    Science.gov (United States)

    Nagalakshmi, R A; Suresh, J; Sivakumar, S; Kumar, R Ranjith; Lakshman, P L Nilantha

    2014-09-01

    The asymmetric unit of the title compound, C21H15Cl2N5O4, contains two independent mol-ecules (A and B) having similar conformations. The amine (NH2) group forms an intra-molecular hydrogen bond with the benzoyl group, giving an S(6) ring motif in both mol-ecules. The central six-membered rings adopt sofa conformations and the imidazole rings are planar (r.m.s deviations = 0.0150 and 0.0166 Å). The pyridine and imidazole rings are inclined to one another by 3.54 (1) and 3.03 (1)° in mol-ecules A and B, respectively. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains along the a axis which enclose R 2 (2)(16) ring motifs. The rings are linked by weak N-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π inter-actions forming sheets lying parallel to (001). A region of disordered electron density, most probably disordered solvent mol-ecules, occupying voids of ca 753 Å(3) for an electron count of 260, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

  4. Crystal structure of N-[(4-eth-oxy-phen-yl)carbamo-thio-yl]cyclo-hexa-ne-carboxamide.

    Science.gov (United States)

    Vimala, G; Haribabu, J; Srividya, S; Karvembu, R; SubbiahPandi, A

    2015-11-01

    The asymmetric unit of the title compound, C16H22N2O2S, contains two crystallographically independent mol-ecules (A and B). In mol-ecule A, the cyclo-hexane ring is disordered over two orientations [occupancy ratio 0.841 (10):0.159 (10)]. In each mol-ecule, the central carbonyl thio-urea unit is nearly planar (r.m.s. deviations for all non-H atoms of 0.034 Å in mol-ecule A and 0.094 Å in mol-ecule B). In both mol-ecules, the cyclo-hexane ring adopts a chair conformation. The mean plane of the cyclo-hexane ring makes dihedral angles of 35.8 (4) (mol-ecule A) and 20.7 (3)° (mol-ecule B) with that of the benzene ring. Each mol-ecule features an intra-molecular N-H⋯O hydrogen bond, which closes an S(6) ring motif. In the crystal, mol-ecules are linked via pairs of weak N-H⋯S inter-actions, forming inversion dimers with an R 2 (2)(8) ring motif for both mol-ecules. The crystal structure also features weak C-H⋯π ring inter-actions.

  5. Crystal structure of N-(4-oxo-2-sulfanyl-idene-1,3-thia-zolidin-3-yl)-2-(thio-phen-3-yl)acetamide.

    Science.gov (United States)

    Vu Quoc, Trung; Nguyen Ngoc, Linh; Nguyen Tien, Cong; Thang Pham, Chien; Van Meervelt, Luc

    2017-06-01

    The title compound, C9H8N2O2S3, crystallizes with two mol-ecules (A and B) in the asymmetric unit. Both have similar conformations (overlay r.m.s. deviation = 0.209 Å) and are linked by an N-H⋯O hydrogen bond. In both mol-ecules, the thio-phene rings show orientational disorder, with occupancy factors of 0.6727 (17) and 0.3273 (17) for mol-ecule A, and 0.7916 (19) and 0.2084 (19) for mol-ecule B. The five-membered rings make an angle of 79.7 (2)° in mol-ecule A and an angle of 66.8 (2)° in mol-ecule B. In the crystal, chains of mol-ecules running along the a-axis direction are linked by N-H⋯O hydrogen bonds. The inter-action of adjacent chains through N-H⋯O hydrogen bonds leads to two types of ring structures containing four mol-ecules and described by the graph-set motifs R4(4)(18) and R4(2)(14).

  6. Crystal structures of three N-(aryl-sulfon-yl)-4-fluoro-benzamides.

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    Suchetan, P A; Naveen, S; Lokanath, N K; Srivishnu, K S; Supriya, G M; Lakshmikantha, H N

    2016-04-01

    The crystal structures of three N-aryl-sulfonyl-4-fluoro-benzamides, namely 4-fluoro-N-(2-methyl-phenyl-sulfon-yl)benzamide, C14H12FNO3S, (I), N-(2-chloro-phenyl-sulfon-yl)-4-fluorobenzamide, C13H9ClFNO3S, (II), and N-(4-chloro-phenyl-sulfon-yl)-4-fluoro-benzamide monohydrate, C13H9ClFNO3S·H2O, (III), are described and compared with related structures. The asymmetric unit of (I) contains two independent mol-ecules (A and B), while that of (II) contains just one mol-ecule, and that of (III) contains a mol-ecule of water in addition to one main mol-ecule. The dihedral angle between the benzene rings is 82.83 (11)° in mol-ecule A and 85.01 (10)° in mol-ecule B of (I), compared to 89.91 (10)° in (II) and 81.82 (11)° in (III). The crystal structure of (I) features strong N-H⋯O hydrogen bonds between the A and B mol-ecules, resulting in an R 4 (4)(16) tetra-meric unit. These tetra-meric units are connected into sheets in the bc plane by various C-H⋯O inter-actions, and adjacent sheets are further inter-linked via C-H⋯πar-yl inter-actions, forming a three-dimensional architecture. The crystal structure is further stabilized by πar-yl-πar-yl and S=O⋯πar-yl inter-actions. In the crystal of (II), mol-ecules are connected into R 2 (2)(8) and R 2 (2)(14) dimers via N-H⋯O hydrogen bonds and C-H⋯O inter-actions, respectively; the dimers are further inter-connected via a weak C=O⋯πar-yl inter-action, leading to the formation of chains along [1-10]. In the crystal of (III), N-H⋯O and O-H⋯O hydrogen bonds involving both the main mol-ecule and the solvent water mol-ecule results in the formation of sheets parallel to the bc plane. The sheets are further connected by C-H⋯O inter-actions and weak C-Cl⋯πar-yl, C-F⋯πar-yl and S=O⋯πar-yl inter-actions, forming a three-dimensional architecture.

  7. Crystal structure of 1,1'-[imidazolidine-1,3-diylbis(methyl-ene)]bis-(naphthalen-2-ol).

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    Rivera, Augusto; Rojas, Jicli José; Ríos-Motta, Jaime; Bolte, Michael

    2015-03-01

    The crystal structure of the title compound, C25H24N2O2, at 173 K has monoclinic (C2/c) symmetry. The mol-ecule is located on a crystallographic twofold rotation axis with only half a mol-ecule in the asymmetric unit. The imidazolidine ring adopts a twist conformation, with a twist about the ring C-C bond. The crystal structure shows the anti-clinal disposition of the two (2-hy-droxy-naphthalen-1-yl)methyl substituents of the imidazolidine ring. The structure displays two intra-molecular O-H⋯N hydrogen bonds, each forming an S(6) ring motif.

  8. Crystal structure of a 2:1 co-crystal of meloxicam with acetyl-endi-carb-oxy-lic acid.

    Science.gov (United States)

    Tantardini, Christian; Arkhipov, Sergey G; Cherkashina, Ksenya A; Kil'met'ev, Alexander S; Boldyreva, Elena V

    2016-12-01

    The pharmaceutical 2:1 co-crystal of meloxicam [MXM; systematic name: 4-hy-droxy-2-methyl-N-(5-methyl-thia-zol-2-yl)-2H-1,2-benzo-thia-zine-3-carboxamide 1,1-dioxide] with acetyl-enedi-carb-oxy-lic acid (ACA; systematic name: but-2-ynedioic acid), crystallizes with one MXM mol-ecule and half an ACA mol-ecule in the asymmetric unit, C14H13N3O4S2·0.5C4H2O4. The mid-point of the triple bond of ACA is located on an inversion centre. In the crystal, the two stereoisomers of MXM with respect to the N atom of the sulfonamide group are related by the inversion centre. The carbonyl and hy-droxy groups belonging to the MXM mol-ecule are involved in an intra-molecular O-H⋯O hydrogen bond. The structure-forming motif includes two MXM mol-ecules linked via an ACA conformer through N-H⋯O and O-H⋯N hydrogen bonds, similar to MXM co-crystals with other di-carb-oxy-lic acids.

  9. Crystal structures of three 3,4,5-tri-meth-oxy-benzamide-based derivatives.

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    Gomes, Ligia R; Low, John Nicolson; Oliveira, Catarina; Cagide, Fernando; Borges, Fernanda

    2016-05-01

    The crystal structures of three benzamide derivatives, viz. N-(6-hy-droxy-hex-yl)-3,4,5-tri-meth-oxy-benzamide, C16H25NO5, (1), N-(6-anilinohex-yl)-3,4,5-tri-meth-oxy-benzamide, C22H30N2O4, (2), and N-(6,6-di-eth-oxy-hex-yl)-3,4,5-tri-meth-oxy-benzamide, C20H33NO6, (3), are described. These compounds differ only in the substituent at the end of the hexyl chain and the nature of these substituents determines the differences in hydrogen bonding between the mol-ecules. In each mol-ecule, the m-meth-oxy substituents are virtually coplanar with the benzyl ring, while the p-meth-oxy substituent is almost perpendicular. The carbonyl O atom of the amide rotamer is trans related with the amidic H atom. In each structure, the benzamide N-H donor group and O acceptor atoms link the mol-ecules into C(4) chains. In 1, a terminal -OH group links the mol-ecules into a C(3) chain and the combined effect of the C(4) and C(3) chains is a ribbon made up of screw related R 2 (2)(17) rings in which the ⋯O-H⋯ chain lies in the centre of the ribbon and the tri-meth-oxy-benzyl groups forms the edges. In 2, the combination of the benzamide C(4) chain and the hydrogen bond formed by the terminal N-H group to an O atom of the 4-meth-oxy group link the mol-ecules into a chain of R 2 (2)(17) rings. In 3, the mol-ecules are linked only by C(4) chains.

  10. Crystal structure of canagliflozin hemihydrate.

    Science.gov (United States)

    Liu, Kai-Hang; Gu, Jian-Ming; Hu, Xiu-Rong; Tang, Gu-Ping

    2016-05-01

    There are two canagliflozin mol-ecules (A and B) and one water mol-ecule in the asymmetric unit of the title compound, C24H25FO5S·0.5H2O [systematic name: (2S,3R,4R,5S,6R)-2-(3-{[5-(4-fluoro-phen-yl)thio-phen-2-yl]meth-yl}-4-methylphen-yl)-6-(hy-droxy-meth-yl)-3,4,5,6-tetra-hydro-2H-pyran-3,4,5-triol hemihydrate]. The dihedral angles between the methyl-benzene and thio-phene rings are 115.7 (4) and 111.7 (4)°, while the dihedral angles between the fluoro-benzene and thio-phene rings are 24.2 (6) and 20.5 (9)° in mol-ecules A and B, respectively. The hydro-pyran ring exhibits a chair conformation in both canagliflozin mol-ecules. In the crystal, the canagliflozin mol-ecules and lattice water mol-ecules are connected via O-H⋯O hydrogen bonds into a three-dimensional supra-molecular architecture.

  11. Crystal structure of 2-amino-4-methyl-pyridin-1-ium (2R,3R)-3-carb-oxy-2,3-di-hydroxy-propano-ate monohydrate.

    Science.gov (United States)

    Jovita, J V; Sathya, S; Usha, G; Vasanthi, R; Ramanand, A

    2014-09-01

    The title mol-ecular salt, C6H9N2 (+)·C4H5O6 (-)·H2O, crystallized with two 2-amino-4-methyl-pyridin-1-ium cations, two l-(+)-tartaric acid monoanions [systematic name: (2R,3R)-3-carb-oxy-2,3-di-hydroxy-propano-ate] and two water mol-ecules in the asymmetric unit. In the crystal, the cations, anions and water mol-ecules are linked via a number of O-H⋯O and N-H⋯O hydrogen bonds, and a C-H⋯O hydrogen bond, forming a three-dimensional structure.

  12. Crystal structure of glycidamide: the mutagenic and genotoxic metabolite of acryl-amide.

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    Hemgesberg, Melanie N; Bonck, Thorsten; Merz, Karl-Heinz; Sun, Yu; Schrenk, Dieter

    2016-08-01

    The title compound, glycidamide (systematic name: oxirane-2-carboxamide), C3H5NO2, is the mutagenic and genotoxic metabolite of acryl-amide, a food contaminant and industrial chemical that has been classified as being probably carcinogenic to humans. Synthesized via the reaction of acrylo-nitrile and hydrogen peroxide, it crystallizes with both enanti-omers occurring as two crystallographically independent mol-ecules (A and B) in the asymmetric unit. They have similar conformations with an r.m.s. deviation of 0.0809 Å for mol-ecule B inverted on mol-ecule A. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, which lead to the formation of β-sheet structures enclosing R 2 (2)(8) and R 4 (2)(8) loops. The β-sheets are linked by weaker C-H⋯O hydrogen bonds, forming a supra-molecular three-dimensional structure.

  13. Crystal and mol-ecular structure of aflatrem.

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    Lenta, Bruno N; Ngatchou, Jules; Kenfack, Patrice T; Neumann, Beate; Stammler, Hans-Georg; Sewald, Norbert

    2015-11-01

    The crystal structure of the title compound, C32H39NO4, confirms the absolute configuration of the seven chiral centres in the mol-ecule. The molecule has a 1,1-dimethylprop-2-enyl substituent on the indole nucleus and this nucleus shares one edge with the five-membered ring which is, in turn, connected to a sequence of three edge-shared fused rings. The skeleton is completed by the 7,7-trimethyl-6,8-dioxabi-cyclo-[3.2.1]oct-3-en-2-one group connected to the terminal cyclohexene ring. The two cyclohexane rings adopt chair and half-chair conformations, while in the dioxabi-cyclo-[3.2.1]oct-3-en-2-one unit, the six-membered ring has a half-chair conformation. The indole system of the mol-ecule exhibits a tilt of 2.02 (1)° between its two rings. In the crystal, O-H⋯O hydrogen bonds connect mol-ecules into chains along [010]. Weak N-H⋯π inter-actions connect these chains, forming sheets parallel to (10-1).

  14. Crystal structure of cis-diamminebis(nitrito-κN)platinum(II).

    Science.gov (United States)

    Kahlenberg, Volker; Gelbrich, Thomas; Tessadri, Richard; Klauser, Frederik

    2015-04-01

    Single crystals of cis-[Pt(NO2)2(NH3)2], were obtained by means of hyper-saturation directly out of a plating electrolyte. The square-planar coordination environment of the divalent Pt(II) atom is formed by four N atoms belonging to two ammine and two monodentate nitrite ligands. The ligands adopt a cis configuration. The crystal structure contains stacks of close-packed mol-ecules which run parallel to [001]. There are nine crystallographically independent inter-molecular N-H⋯O hydrogen bonds, resulting in a hydrogen-bonded hxl-type framework in which each mol-ecule serves as an eight-connected node. Four of the nine distinct hydrogen bonds connect complexes which belong to the same close-packed column parallel to [001]. In contrast to the previously reported crystal structure of the trans isomer, the title structure does not display intra-molecular hydrogen bonding.

  15. Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium bromide 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate.

    Science.gov (United States)

    Kathiravan, Perumal; Balakrishnan, Thangavelu; Venkatesan, Perumal; Ramamurthi, Kandasamy; Percino, María Judith; Thamotharan, Subbiah

    2016-11-01

    In the title mol-ecular salt, C9H12NO4(+)·Br(-)·C9H11NO4, one of the dopa mol-ecules is in the cationic form in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged, while the second dopa mol-ecule is in the zwitterion form. The Br(-) anion occupies a special position and is located on a twofold rotation axis. The two dopa mol-ecules are inter-connected by short O-H⋯O hydrogen bonds. In the crystal, the various units are linked by O-H⋯O, N-H⋯Br and N-H⋯O hydrogen bonds, forming a three-dimensional framework. The title compound was refined as an inversion twin with an absolute structure parameter of 0.023 (8).

  16. Crystal structure of tris[(4,7,13,16,21,24-hexa-oxa-1,10-di-aza-bicyclo-[8.8.8]hexa-cosane-κ(8)N2,O6)rubidium] rubidium nona-stannide.

    Science.gov (United States)

    Klein, Wilhelm; He, Haiyan; Fässler, Thomas F

    2017-02-01

    The crystal structure of the title compound, [Rb(C18H36N2O6)]3RbSn9, consists of deltahedral [Sn9](4-) cluster anions, Rb(+) cations and cryptand mol-ecules, which partially sequester the cations. Those cations, which are not coordinated by cryptand mol-ecules, are neighboured directly to the [Sn9](4-) clusters and inter-connect them to form ∞(1)[RbSn9](3-) chains. These chains extend parallel to [001] and are arranged in a pseudo-hexa-gonal rod packing, separated by the Rb-cryptand complex cations.

  17. Crystal structures of (2E)-1-(3-bromo-thio-phen-2-yl)-3-(2-meth-oxy-phen-yl)prop-2-en-1-one and (2E)-1-(3-bromo-thio-phen-2-yl)-3-(3,4-di-meth-oxy-phen-yl)prop-2-en-1-one.

    Science.gov (United States)

    Naik, Vasant S; Shettigar, Venkataraya; Berglin, Tyler S; Coburn, Jillian S; Jasinski, Jerry P; Yathirajan, Hemmige S

    2015-08-01

    In the mol-ecules of the title compounds, (2E)-1-(3-bromo-thio-phen-2-yl)-3-(2-meth-oxy-phen-yl)prop-2-en-1-one, C14H11BrO2S, (I), which crystallizes in the space group P-1 with four independent mol-ecules in the asymmetric unit (Z' = 8), and (2E)-1-(3-bromo-thio-phen-2-yl)-3-(3,4-di-meth-oxy-phen-yl)prop-2-en-1-one, C15H13BrO3S, (II), which crystallizes with Z' = 8 in the space group I2/a, the non-H atoms are nearly coplanar. The mol-ecules of (I) pack with inversion symmetry stacked diagonally along the a-axis direction. Weak C-H⋯Br intra-molecular inter-actions in each of the four mol-ecules in the asymmetric unit are observed. In (II), weak C-H⋯O, bifurcated three-center inter-molecular inter-actions forming dimers along with weak C-H⋯π and π-π stacking inter-actions are observed, linking the mol-ecules into sheets along [001]. A weak C-H⋯Br intra-molecular inter-action is also present. There are no classical hydrogen bonds present in either structure.

  18. Crystal structures of hydrogen-bonded co-crystals as liquid crystal precursors: 4-(n-pent-yloxy)benzoic acid-(E)-1,2-bis-(pyridin-4-yl)ethene (2/1) and 4-(n-hex-yloxy)benzoic acid-(E)-1,2-bis-(pyridin-4-yl)ethene (2/1).

    Science.gov (United States)

    Tabuchi, Yohei; Gotoh, Kazuma; Ishida, Hiroyuki

    2016-12-01

    The crystal structures of title hydrogen-bonded co-crystals, 2C12H16O3·C12H10N2, (I), and 2C13H18O3·C12H10N2, (II), have been determined at 93 K. In (I), the asymmetric unit consists of one 4-(n-pent-yloxy)benzoic acid mol-ecule and one half-mol-ecule of (E)-1,2-bis-(pyridin-4-yl)ethene, which lies about an inversion centre. The asymmetric unit of (II) comprises two crystallographically independent 4-(n-hex-yloxy)benzoic acid mol-ecules and one 1,2-bis-(pyridin-4-yl)ethene mol-ecule. In each crystal, the acid and base components are linked by O-H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. The 2:1 units are linked via C-H⋯π and π-π inter-actions [centroid-centroid distances of 3.661 (2) and 3.909 (2) Å for (I), and 3.546 (2)-3.725 (4) Å for (II)], forming column structures. In (II), the base mol-ecule is orientationally disordered over two sets of sites approximately around the N⋯N mol-ecular axis, with an occupancy ratio of 0.647 (4):0.353 (4), and the average structure of the 2:1 unit adopts nearly pseudo-C2 symmetry. Both compounds show liquid-crystal behaviour.

  19. Crystal structures of three (trichloromethyl)(carbamoyl)disulfanes.

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    Goldenberg, Barbara L; Young, Victor G; Barany, George

    2015-10-01

    The present paper reports crystallographic studies on three related compounds that were of inter-est as precursors for synthetic and mechanistic work in organosulfur chemistry, as well as to model nitro-gen-protecting groups: (N-methyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C3H4Cl3NOS2, (1), (N-benzyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C9H8Cl3NOS2, (2), and (N-methyl-N-phenyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C9H8Cl3NOS2, (3). Their mol-ecular structures, with similar bond lengths and angles for the CCl3SS(C=O)N moieties, are confirmed. Compounds (1) and (3) both crystallized with two independent mol-ecules in the asymmetric unit. Classical hydrogen bonding, as well as chlorine-dense regions, are evident in the crystal packing for (1) and (2). In the crystal of (1), mol-ecules are linked via N-H⋯O hydrogen bonds forming chains along [110], which are linked by short Cl⋯Cl and S⋯O contacts forming sheets parallel to (001). In the crystal of (2), mol-ecules are linked via N-H⋯O hydrogen bonds forming chains along [001], which in turn are linked by pairs of short O⋯Cl contacts forming ribbons along the c-axis direction. In the crystal of (3), there are no classical hydrogen bonds present and the chlorine-dense regions observed in (1) and (2) are lacking.

  20. Selective crystallization of indigo B by a modified sublimation method and its redetermined structure.

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    Kettner, Florian; Hüter, Lucie; Schäfer, Johanna; Röder, Konstantin; Purgahn, Uta; Krautscheid, Harald

    2011-11-01

    Good-quality single crystals of the title compound, indigo B [systematic name: 2-(3-oxoindolin-2-yl-idene)indolin-3-one], C(16)H(10)N(2)O(2), have been prepared with high selectivity by a sublimation process. The previous structure of indigo B [Süsse & Wolf (1980 ▶). Naturwissenschaften, 67, 453], which showed that the complete mol-ecule is generated by crystallographic inversion symmetry has been confirmed, but the present study reports more realistic geometrical parameters and modern standards of precision (e.g. σ for C-C bonds = 0.002-0.003 Å). Each mol-ecule features two intra-molecular N-H⋯O hydrogen bonds. In the crystal, mol-ecules are linked by strong face-to-face π-π stacking inter-actions involving both the six- and five-membered rings [centroid-centroid separations = 3.6290 (14) and 3.6506 (14) Å] and inter-molecular N-H⋯O hydrogen bonds.

  1. Crystal structures of two nickel compounds comprising neutral Ni(II) hydrazone complexes and di-carb-oxy-lic acids.

    Science.gov (United States)

    Nakanishi, Takumi; Sato, Osamu

    2017-02-01

    Two isostructural Ni(II) compounds, bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-chloro-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Cl2O4), and bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-bromo-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Br2O4), were synthesized and their crystal structures determined. The pair of N,N',O-tridentate N-[1-(pyridin-2-yl-κN)eth-yl]pyridine-4-carbohydrazonate L ligands result in a cis-NiO2N4 octa-hedral coordination sphere for the metal ions. The asymmetric units consist of two half-mol-ecules of the di-carb-oxy-lic acids, which are completed by crystallographic inversion symmetry. In the respective crystals, the 2,5-di-chloro-terephthalic acid (H2Cl2TPA, 1-Cl) mol-ecules form zigzag hydrogen-bonded chains with the [Ni(L)2] mol-ecules, with the hydrogen-bond distances in 1-Br slightly longer than those in 1-Cl. The packing is consolidated by aromatic π-π stacking between the di-carb-oxy-lic acid mol-ecules and terminal pyridine rings in [Ni(L)2] and short halogen-halogen inter-actions are also observed. The qualitative prediction of the H-atom position from the C-N-C angles of the terminal pyridine rings in L and the C-O distances in the carboxyl groups show that 1-Cl and 1-Br are co-crystals rather than salts.

  2. Crystal structure of (E)-4-hy-droxy-N'-(3-meth-oxy-benzyl-idene)benzohydrazide.

    Science.gov (United States)

    Chantrapromma, Suchada; Prachumrat, Patcharawadee; Ruanwas, Pumsak; Boonnak, Nawong; Kassim, Mohammad B

    2016-09-01

    The title compound, C15H14N2O3, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit that differ in the orientation of the 3-meth-oxy-phenyl group with respect to the methyl-idenebenzohydrazide unit. The dihedral angles between the two benzene rings are 24.02 (10) and 29.30 (9)° in mol-ecules A and B, respectively. In mol-ecule A, the meth-oxy group is twisted slightly relative to its bound benzene ring, with a Cmeth-yl-O-C-C torsion angle of 14.2 (3)°, whereas it is almost co-planar in mol-ecule B, where the corresponding angle is -2.4 (3)°. In the crystal, the mol-ecules are linked by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, as well as by weak C-H⋯O inter-actions, forming sheets parallel to the bc plane. The N-H⋯O hydrogen bond and weak C-H⋯O inter-action link different mol-ecules (A⋯B) whereas both O-H⋯N and O-H⋯O hydrogen bonds link like mol-ecules (A⋯A) and (B⋯B). Pairs of inversion-related B mol-ecules are stacked approximately along the a axis by π-π inter-actions in which the distance between the centroids of the 3-meth-oxy-phenyl rings is 3.5388 (12) Å. The B mol-ecules also participate in weak C-H⋯π inter-actions between the 4-hy-droxy-phenyl and the 3-meth-oxy-phenyl rings.

  3. Crystal and mol-ecular structure of meso-2,6-di-bromo-hepta-nedioic acid (meso-2,6-di-bromo-pimelic acid).

    Science.gov (United States)

    Dirda, Nathaniel D A; Zavalij, Peter Y; Kao, Joseph P Y

    2016-03-01

    The mol-ecular structure of the title compound, C7H10Br2O4, confirms the meso (2R,6S) configuration. In the crystal, mol-ecules are linked by pairs of O-H⋯O=C hydrogen bonds between their terminal carboxyl groups in an R 2 (2)(8) motif, forming extended chains that propagate parallel to the c axis. Adjacent chains are linked by C=O⋯Br halogen bonds.

  4. Crystal structure of (E)-2-[(2-bromopyridin-3-yl)methyl-idene]-6-meth-oxy-3,4-di-hydro-naphthalen-1(2H)-one and 3-[(E)-(6-meth-oxy-1-oxo-1,2,3,4-tetra-hydro-naphthalen-2-ylidene)meth-yl]pyridin-2(1H)-one.

    Science.gov (United States)

    Zingales, Sarah K; Moore, Morgan E; Goetz, Andrew D; Padgett, Clifford W

    2016-07-01

    The title compounds C17H14BrNO2, (I), and C17H15NO3, (II), were obtained from the reaction of 6-meth-oxy-3,4-di-hydro-2H-naphthalen-1-one and 2-bromo-nicotinaldehyde in ethanol. Compound (I) was the expected product and compound (II) was the oxidation product from air exposure. In the crystal structure of compound (I), there are no short contacts or hydrogen bonds. The structure does display π-π inter-actions between adjacent benzene rings and adjacent pyridyl rings. Compound (II) contains two independent mol-ecules, A and B, in the asymmetric unit; both are non-planar, the dihedral angles between the meth-oxy-benzene and 1H-pyridin-2-one mean planes being 35.07 (9)° in A and 35.28 (9)°in B. In each mol-ecule, the 1H-pyridin-2-one unit participates in inter-molecular N-H⋯O hydrogen bonding to another mol-ecule of the same type (A to A or B to B). The structure also displays π-π inter-actions between the pyridyl and the benzene rings of non-equivalent mol-ecules (viz., A to B and B to A).

  5. Crystal structures of 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1) and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2).

    Science.gov (United States)

    Gotoh, Kazuma; Ishida, Hiroyuki

    2017-07-01

    The crystal structures of two hydrogen-bonded compounds, namely 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1), C13H14.59N2·C8H7.67O3·C8H7.74O3, (I), and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2), C14H9.43O4·C6H7.32NO·C6H7.25NO, (II), have been determined at 93 K. In (I), the asymmetric unit consists of two crystallographically independent 4-meth-oxy-benzoic acid mol-ecules and one 1,3-bis-(pyridin-4-yl)propane mol-ecule. The asymmetric unit of (II) comprises one biphenyl-4,4'-di-carb-oxy-lic acid mol-ecule and two independent 4-meth-oxy-pyridine mol-ecules. In each crystal, the acid and base mol-ecules are linked by short O-H⋯N/N-H⋯O hydrogen bonds, in which H atoms are disordered over the acid O-atom and base N-atom sites, forming a linear hydrogen-bonded 2:1 or 1:2 unit of the acid and the base. The 2:1 units of (I) are linked via C-H⋯π, π-π and C-H⋯O inter-actions into a tape structure along [101], while the 1:2 units of (II) form a double-chain structure along [-101] through π-π and C-H⋯O inter-actions.

  6. Crystal structure of (1,3-di-tert-butyl-η(5)-cyclo-penta-dien-yl)tri-methyl-hafnium(IV).

    Science.gov (United States)

    Pérez-Redondo, Adrián; Varela-Izquierdo, Víctor; Yélamos, Carlos

    2015-05-01

    The mol-ecule of the title organometallic hafnium(IV) com-pound, [Hf(CH3)3(C13H21)] or [HfMe3(η(5)-C5H3-1,3- (t) Bu2)], adopts the classical three-legged piano-stool geometry for mono-cyclo-penta-dienylhafnium(IV) derivatives with the three methyl groups bonded to the Hf(IV) atom at the legs. The C atoms of the two tert-butyl group bonded to the cyclo-penta-dienyl (Cp) ring are 0.132 (5) and 0.154 (6) Å above the Cp least-squares plane. There are no significant inter-molecular inter-actions present between the mol-ecules in the crystal structure.

  7. Crystal structure of cis-bis-(μ-β-alanine-κ(2) O:O')bis[tri-chlorido-rhenium(III)](Re-Re) sesquihydrate.

    Science.gov (United States)

    Golichenko, Alexander A; Domasevitch, Konstantin V; Kytova, Dina E; Shtemenko, Alexander V

    2015-01-01

    The structure of the title compound, [Re2Cl6(C3H7NO2)2]·1.5H2O, comprises a dinuclear complex cation [Re-Re = 2.2494 (3) Å] involving cis-oriented double carboxyl-ate bridges, four equatorial chloride ions and two weakly bonded chloride ligands in the axial positions at the two rhenium(III) atoms. In the crystal, two complex mol-ecules and two water mol-ecules constitute hydrogen-bonded dimers, while an extensive hydrogen-bonding network involving the groups of the zwitterionic ligand is important for generation of the framework. An additional partially occupied water molecule is disordered over two sets of sites about a symmetry centre with a site-occupancy ratio of 0.3:0.2.

  8. Supra-molecular inter-actions in the 1:2 co-crystal of 4,4'-bipyridine and 3-chloro-thio-phene-2-carb-oxy-lic acid.

    Science.gov (United States)

    Prajina, Olakkandiyil; Thomas Muthiah, Packianathan; Geiger, David K

    2016-10-01

    The asymmetric unit of the title compound, 2C5H3ClO2S·C10H8N2, is comprised of a mol-ecule of 3-chloro-thio-phene-2-carb-oxy-lic acid (3TPC) and half of a mol-ecule of 4,4'-bi-pyridine (BPY). A distinctive O-H⋯N-based synthon is present. Cl⋯Cl and π-π stacking inter-actions further stabilize the crystal structure, forming a two-dimensional network parallel to the bc plane.

  9. Crystal structure of γ-ethyl-l-glutamate N-carb-oxy anhydride.

    Science.gov (United States)

    Kanazawa, Hitoshi; Inada, Aya

    2015-01-01

    In the title compound (alternative name N-carboxy-l-glutamic anhydride γ-ethyl ester), C8H11NO5, the oxazolidine ring is essentially planar, with a maximum deviation of 0.019 (2) Å. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the ethyl ester group, forming a tape structure along the c-axis direction. The oxazolidine rings of adjacent tapes are arranged into a layer parallel to the ac plane. This arrangement is favourable for the polymerization of the title compound in the solid state.

  10. Crystal structure of 2,4,6-tris-(cyclo-hex-yloxy)-1,3,5-triazine.

    Science.gov (United States)

    Sankolli, Ravish; Hauser, Jürg; Row, T N Guru; Hulliger, Jürg

    2015-11-01

    The title compound, C21H33N3O3, is a tri-substituted cyclo-hex-yloxy triazine. In the crystal, the triazine rings form (C3i-PU) Piedfort units. The inter-centroid distance of the π-π inter-action involving the triazine rings is 3.3914 (10) Å. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming ribbons propagating along [1-10]. There are also weak C-H⋯N and C-H⋯O contacts present, linking inversion-related ribbons, forming a three-dimensional structure.

  11. Channels with ordered water and bipyridine mol-ecules in the porous coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10N2H8·5H2O} n.

    Science.gov (United States)

    Aubert, Emmanuel; Doudouh, Abdelatif; Peluso, Paola; Mamane, Victor

    2016-11-01

    The coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10H8N2·5H2O} n , systematic name: poly[[bis-(μ2-4,4'-bi-pyridine)(μ2-hexa-fluorido-silicato)copper(II)] 4,4'-bi-pyridine disolvate penta-hydrate], contains pores which are filled with water and 4,4'-bi-pyridine mol-ecules. As a result of the presence of these ordered species, the framework changes its symmetry from P4/mmm to P21/c. The 4,4'-bi-pyridine guest mol-ecules form chains inside the 6.5 × 6.9 Å pores parallel to [100] in which the mol-ecules inter-act through π-π stacking. Ordered water mol-ecules form infinite hydrogen-bonded chains inside a second pore system (1.6 × 5.3 Å free aperture) perpendicular to the 4,4'-bi-pyridine channels.

  12. Crystal structure of bis-[tetra-kis-(tri-phenyl-phosphane-κP)silver(I)] (nitrilo-tri-acetato-κ(4) N,O,O',O'')(tri-phenyl-phosphane-κP)argentate(I) with an unknown amount of methanol as solvate.

    Science.gov (United States)

    Noll, Julian; Korb, Marcus; Lang, Heinrich

    2016-03-01

    The structure of the title compound, [Ag(C18H15P)4]2[Ag(C6H6NO6)(C18H15P)], exhibits trigonal (P-3) symmetry, with a C 3 axis through all three complex ions, resulting in an asymmetric unit that contains one third of the atoms present in the formula unit. The formula unit thus contains two of the cations, one anion and disordered mol-ecules of methanol as the packing solvent. Attempts to refine the solvent model were unsuccessful, indicating uninter-pretable disorder. Thus, the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18] was applied, accounting for 670 electrons per unit cell, representing approximately 18 mol-ecules of methanol in the formula unit. The stated crystal data for M r, μ etc do not take these into account.

  13. Crystal structure of bis-(2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)manganese(IV) 0.39-hydrate.

    Science.gov (United States)

    Buvaylo, Elena A; Vassilyeva, Olga Yu; Skelton, Brian W

    2015-11-01

    The title compound, [Mn(C12H15NO5)2]·0.39H2O, is a 0.39 hydrate of the isostructural complex bis-(2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)manganese(IV) that has previously been reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941-947], based on room-temperature data. The current structure that was determined at 100 K reveals a lengthening of the c cell parameter compared with the published one due to the incorporation of the partial occupancy water mol-ecule. The title compound crystallizes in the tetra-gonal chiral space group P41212; the neutral [Mn(IV)(C12H15NO5)2] mol-ecule is situated on a crystallographic C 2 axis. The overall geometry about the central manganese ion is octa-hedral with an N2O4 core; each ligand acts as a meridional ONO donor. The coordination environment of Mn(IV) at 100 K displays a difference in one of the two Mn-O bond lengths, compared with the room-temperature structure. In the crystal, the neutral mol-ecules are stacked in a helical fashion along the c-axis direction.

  14. Crystal structures of four co-crystals of (E)-1,2-di(pyridin-4-yl)ethene with 4-alk-oxy-benzoic acids: 4-meth-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), 4-eth-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), 4-n-propoxybenzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1) and 4-n-but-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1).

    Science.gov (United States)

    Tabuchi, Yohei; Gotoh, Kazuma; Ishida, Hiroyuki

    2016-11-01

    The crystal structures of four hydrogen-bonded co-crystals of 4-alk-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), namely, 2C8H8O3·C12H10N2, (I), 2C9H10O3·C12H10N2, (II), 2C10H12O3·C12H10N2, (III) and 2C11H14O3·C12H10N2, (IV), have been determined at 93 K. In compounds (I) and (IV), the asymmetric units are each composed of one 4-alk-oxy-benzoic acid mol-ecule and one half-mol-ecule of (E)-1,2-di(pyridin-4-yl)ethene, which lies on an inversion centre. The asymmetric unit of (II) consists of two crystallographically independent 4-eth-oxy-benzoic acid mol-ecules and one 1,2-di(pyridin-4-yl)ethene mol-ecule. Compound (III) crystallizes in a non-centrosymmetric space group (Pc) and the asymmetric unit comprises four 4-n-propoxybenzoic acid mol-ecules and two (E)-1,2-di(pyridin-4-yl)ethane mol-ecules. In each crystal, the acid and base components are linked by O-H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. In (I), (II) and (III), inter-molecular C-H⋯O inter-actions are observed. The 2:1 units of (I) and (II) are linked via C-H⋯O hydrogen bonds, forming tape structures. In (III), the C-H⋯O hydrogen bonds, except for those formed in the units, link the two crystallographically independent 2:1 units. In (IV), no C-H⋯O inter-actions are observed, but π-π and C-H⋯π inter-actions link the units into a column structure.

  15. Crystal structure of benzene-1,3,5-tri-carb-oxy-lic acid-4-pyridone (1/3).

    Science.gov (United States)

    Staun, Selena L; Oliver, Allen G

    2015-11-01

    Slow co-crystallization of a solution of benzene-1,3,5-tri-carb-oxy-lic acid with a large excess of 4-hy-droxy-pyridine produces an inter-penetrating, three-dimensional, hydrogen-bonded framework consisting of three 4-pyridone and one benzene-1,3,5-tri-carb-oxy-lic acid mol-ecules, C9H6O6·3C5H5NO. This structure represents an ortho-rhom-bic polymorph of the previously reported C-centered, monoclinic structure [Campos-Gaxiola et al. (2014 ▸). Acta Cryst. E70, o453-o454].

  16. Crystal structure of dimethyl 3,4,5,6-tetra-phenyl-cyclo-hexa-3,5-diene-1,2-di-carboxyl-ate.

    Science.gov (United States)

    Greenberg, Fred H; Nazarenko, Alexander Y

    2016-07-01

    In the title compound, C34H28O4, the cyclo-hexa-diene ring has a screw-boat conformation with a torsion angle between the double bonds being on average ca 15° [15.2 (3) and -15.3 (3) in the two independent mol-ecules]. All four phenyl rings in both mol-ecules are arranged in a propeller-like conformation. The two mol-ecules exhibit S,R- and R,S- chirality, respectively, and are connected via C-H⋯O inter-molecular inter-actions. In turn, these weakly bound dimers form the mol-ecular crystal.

  17. Crystal structure of tri-aqua-(2,6-di-methyl-pyrazine-κN (4))bis-(thio-cyanato-κN)manganese(II) 2,5-di-methyl-pyrazine disolvate.

    Science.gov (United States)

    Suckert, Stefan; Wöhlert, Susanne; Jess, Inke; Näther, Christian

    2015-12-01

    In the crystal structure of the title complex, [Mn(NCS)2(C6H8N2)(H2O)3]·2C6H8N2, the Mn(II) cation is coordinated by two terminally N-bonded thio-cyanate anions, three water mol-ecules and one 2,6-di-methyl-pyrazine ligand within a slightly distorted N3O3 octa-hedral geometry; the entire complex mol-ecule is generated by the application of a twofold rotation axis. The asymmetric unit also contains an uncoordinating 2,5-di-methyl-pyrazine ligand in a general position. Obviously, the coordination to the 2,6-di-methyl-pyrazine ligand is preferred because coordination to the 2,5-di-methyl-pyrazine is hindered due to the bulky methyl group proximate to the N atom. The discrete complexes are linked by water-O-H⋯N(2,6-di-methyl-pyzazine/2,5-di-methyl-pyza-zine) hydrogen bonding, forming a three-dimensional network. In the crystal, mol-ecules are arranged in a way that cavities are formed in which unspecified, disordered solvent molecules reside. These were modelled employing the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The composition of the unit cell does not take into account the presence of the unspecified solvent.

  18. Crystal structure of cis-2-(2-carb-oxy-cyclo-prop-yl)glycine (CCG-III) monohydrate.

    Science.gov (United States)

    Lindeman, Sergey; Wallock, Nathaniel J; Donaldson, William A

    2015-07-01

    The title compound, C6H9NO4·H2O [systematic name: (αR,1R,2S)-rel-α-amino-2-carb-oxy-cyclo-propane-acetic acid monohydrate], crystallizes with two organic mol-ecules and two water mol-ecules in the asymmetric unit. The space group is P21 and the organic mol-ecules are enanti-omers, thus this is an example of a 'false conglomerate' with two mol-ecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one mol-ecule and its inverted partner). Each mol-ecule exists as a zwitterion, with proton transfer from the amino acid carb-oxy-lic acid group to the amine group. In the crystal, the components are linked by N-H⋯O and O-H⋯O hydrogen bonds, generating (100) sheets. Conformationally restricted glutamate analogs are of inter-est due to their selective activation of different glutamate receptors, and the naturally occurring (+)-CCG-III is an inhibitor of glutamate uptake and the key geometrical parameters are discussed.

  19. Crystal structure of 2-(2-amino-phen-yl)-1,3-benzoxazole.

    Science.gov (United States)

    Pérez-Pérez, Imelda; Martínez-Otero, Diego; Rojas-Lima, Susana; López-Ruiz, Heraclio

    2015-02-01

    Crystals of the title compound, C13H10N2O, were grown from a di-chloro-methane/ketone/methanol solvent mixture. It crystallizes with two mol-ecules, A and B, in the asymmetric unit with very similar almost planar conformations [dihedral angles between the ring planes = 0.74 (8) and 0.67 (6)° for mol-ecules A and B, respectively; r.m.s. overlay fit = 0.019 Å]. Each mol-ecule features an intra-molecular N-H⋯N hydrogen bond, which closes an S(6) ring and therefore establishes a syn relationship for the N atoms. In the crystal, mol-ecules are linked by N-H⋯N hydrogen bonds, generating [100] chains containing alternating A and B mol-ecules. Weak aromatic π-π stacking [minimum centroid-centroid separation = 3.6212 (9) Å] links the chains into a three-dimensional network.

  20. Crystal structure of tris-(trans-1,2-cyclo-hexa-ne-diamine-κ(2) N,N')chromium(III) tetra-chlorido-zincate chloride trihydrate from synchrotron data.

    Science.gov (United States)

    Moon, Dohyun; Choi, Jong-Ha

    2016-05-01

    The structure of the title double salt, [Cr(rac-chxn)3][ZnCl4]Cl·3H2O (chxn is trans-1,2-cyclo-hexa-nedi-amine; C6H14N2), has been determined from synchrotron data. The Cr(III) ion is coordinated by six N atoms of three chelating chxn ligands, displaying a slightly distorted octa-hedral coordination environment. The distorted tetra-hedral [ZnCl4](2-) anion, the isolated Cl(-) anion and three lattice water mol-ecules remain outside the coordination sphere. The Cr-N(chxn) bond lengths are in a narrow range between 2.0737 (12) and 2.0928 (12) Å; the mean N-Cr-N bite angle is 82.1 (4)°. The crystal packing is stabilized by hydrogen-bonding inter-actions between the amino groups of the chxn ligands and the water mol-ecules as donor groups, and O atoms of the water mol-ecules, chloride anions and Cl atoms of the [ZnCl4](2-) anions as acceptor groups, leading to the formation of a three-dimensional network. The [ZnCl4](2-) anion is disordered over two sets of sites with an occupancy ratio of 0.94:0.06.

  1. Crystal structure of μ6-chlorido-nona-kis-(μ-4-chloro-pyrazolato)bis-μ3-methoxo-hexa-copper(II).

    Science.gov (United States)

    Shi, Kaige; Mathivathanan, Logesh; Raptis, Raphael G

    2017-02-01

    The hexa-nuclear title compound, [{Cu3(μ3-OCH3)(μ-C3H2ClN2)3}2(μ-C3H2ClN2)3(μ6-Cl)] or [Cu6(C3H2ClN2)9(CH3O)2Cl], crystallizes in the space group Pbcn, with individual mol-ecules being located on a twofold rotation axis. The mol-ecule adopts a trigonal prismatic shape, with two trinuclear units linked by three 4-chloro-pyrazolate ligand bridges by encapsulating a Cl(-) anion in a μ6-coordination mode. In the crystal, individual mol-ecules are stacked into rods parallel to [1-10] that are arranged in a pseudo-hexa-gonal packing. Cohesion between mol-ecules is accomplished through weak C-H⋯Cl inter-actions.

  2. Crystal structure of tetra-kis-(μ3-2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)tetra-kis-[aqua-copper(II)]: a redetermination at 200 K.

    Science.gov (United States)

    Buvaylo, Elena A; Vassilyeva, Olga Yu; Skelton, Brian W

    2015-10-01

    The crystal structure of the tetra-nuclear title compound, [Cu4(C12H15NO5)4(H2O)4], has been previously reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941-947], based on room-temperature data. In the previously published structure, no standard uncertainties are recorded for the deprotonated hy-droxy-methyl group and water mol-ecule O atoms coordinating to the metal atom indicating that they were not refined; furthermore, the H atoms of some OH groups and water mol-ecules have not been positioned accurately. Since the current structure was determined at a lower temperature, all atoms, including the H atoms of these hy-droxy groups and the water mol-ecule, have been determined more accurately resulting in improved standard uncertainties in the bond lengths and angles. Diffraction data were collected at 200 K, rather than the more usual 100 K, due to apparent disordering at lower temperatures. In addition, it is now possible to report intra- and inter-molecular O-H⋯O inter-actions. In the title complex molecule, which has crystallographic -4 symmetry, the Cu(II) ions are coordinated by the tridentate Schiff base ligands and water mol-ecules, forming a tetra-nuclear Cu4O4 cubane-like core. The Cu(II) ion adopts a CuNO5 elongated octa-hedral environment. The coordination environment of Cu(II) at 200 K displays a small contraction of the Cu-N/O bonds, compared with the room-temperature structure. In the crystal lattice, the neutral clusters are linked by inter-molecular O-H⋯O hydrogen bonds into a one-dimensional hydrogen-bonding network propagating along the b axis.

  3. Redetermined crystal structure of N-(β-carb-oxy-eth-yl)-α-isoleucine.

    Science.gov (United States)

    Chandrarekha, M; Srinivasan, N; Krishnakumar, R V

    2015-09-01

    Redetermination of the crystal structure of N-(β-carb-oxy-eth-yl)-α-isoleucine, C9H18N2O3, reported earlier by Nehls et al. [Acta Cryst. (2013), E69, o172-o173], was undertaken in which the ionization state assigned to the mol-ecule as unionized has been modified as zwitterionic in the present work. Single-crystal X-ray intensity data obtained from freshly grown crystals and freely refining the amino H atoms provide enhanced refinement and structural parameters, particularly the hydrogen-bonding scheme. N-H⋯O hydrogen bonds dominate the inter-molecular inter-actions along with a C-H⋯O hydrogen bond. The inter-molecular inter-action pattern is a three-dimensional network. The structure was refined as a two-component perfect inversion twin.

  4. Crystal structure of 6,6,12,12-tetra-chloro-tri-cyclo-[8.2.0.0(4,7)]dodecane-5,11-dione.

    Science.gov (United States)

    Turan Akın, Esra; Hökelek, Tuncer

    2015-09-01

    The asymmetric unit of the title compound, C12H12Cl4O2, contains two crystallographically independent mol-ecules with almost identical conformations (r.m.s. overlay fit for the non-hydrogen atoms = 0.059 Å). In each mol-ecule, the central eight-membered ring has a distorted boat configuration, and two non-planar four-membered rings are fused on either side of the eight-membered ring. A weak C-H⋯O hydrogen bond links the two independent mol-ecules. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into a two-dimensional network parallel to (001).

  5. Crystal structure of 4-(meth-oxy-carbon-yl)phenyl-boronic acid.

    Science.gov (United States)

    Flanagan, Keith J; Senge, Mathias O

    2015-10-01

    In the title compound, C8H9BO4, the meth-oxy-carbonyl group is rotated out of the plane of the benzene ring by 7.70 (6)°. In the crystal, mol-ecules are linked via pairs of O-H⋯O hydrogen bonds, involving the boronic acid OH groups, forming inversion dimers. The dimers are linked via O-H⋯O hydrogen bonds, involving a boronic acid OH group and the carbonyl O atom, forming undulating sheets parallel to (10-2). Within the sheets there are also C-H⋯O hydrogen bonds present, also involving the carbonyl O atom. The sheets are linked via C-H⋯π and offset face-to-face π-inter-actions between inversion-related mol-ecules [inter-centroid distance = 3.7843 (16) Å, inter-planar distance = 3.3427 (4) Å and offset = 1.744 Å], forming a three-dimensional structure.

  6. Crystal structure of (E)-2-hy-droxy-4'-meth-oxy-aza-stilbene.

    Science.gov (United States)

    Chantrapromma, Suchada; Kaewmanee, Narissara; Boonnak, Nawong; Chantrapromma, Kan; Ghabbour, Hazem A; Fun, Hoong-Kun

    2015-06-01

    The title aza-stilbene derivative, C14H13NO2 {systematic name: (E)-2-[(4-meth-oxy-benzyl-idene)amino]-phenol}, is a product of the condensation reaction between 4-meth-oxy-benzaldehyde and 2-amino-phenol. The mol-ecule adopts an E conformation with respect to the azomethine C=N bond and is almost planar, the dihedral angle between the two substituted benzene rings being 3.29 (4)°. The meth-oxy group is coplanar with the benzene ring to which it is attached, the Cmeth-yl-O-C-C torsion angle being -1.14 (12)°. There is an intra-molecular O-H⋯N hydrogen bond generating an S(5) ring motif. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, forming zigzag chains along [10-1]. The chains are linked via C-H⋯π inter-actions, forming a three-dimensional structure.

  7. Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy-droxy-7-meth-oxy-meth-oxy-11,15,18,18-tetra-methyl-3-oxo-2,4-dioxa-tetra-cyclo-[12.3.1.0(1,5).0(6,11)]octa-dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative.

    Science.gov (United States)

    Oishi, Takeshi; Fukaya, Keisuke; Yamaguchi, Yu; Sugai, Tomoya; Watanabe, Ami; Sato, Takaaki; Chida, Noritaka

    2015-05-01

    The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra-cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (A), there are two independent benzoate mol-ecules (A and A') and a half mol-ecule of solvent pentane disordered about an inversion center. The mol-ecular conformations of (A), (B) and (C) are similar except for the flexible meth-oxy-meth-oxy group. The cyclo-hexane, cyclo-hexene and central cyclo-octane rings adopt chair, half-chair and chair-chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A' is slightly twisted from the mean plane. In the crystal of (A), inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol-ecules are linked through O-H⋯O and C-H⋯π inter-actions, and C-H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter-molecular C-H⋯O inter-actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).

  8. Crystal structure of paddle-wheel sandwich-type [Cu2{(CH3)2CO}{μ-Fe(η(5)-C5H4C N)2}3](BF4)2·(CH3)2CO.

    Science.gov (United States)

    Strehler, Frank; Korb, Marcus; Lang, Heinrich

    2015-02-01

    The mol-ecular structure of (acetone-κO)tris-(μ-ferrocene-1,1'-dicarbo-nitrile-κ(2) N:N')dicopper(I) bis-(tetra-fluorido-borate) acetone monosolvate, [Cu2Fe3(C6H4N)6(C3H6O)](BF4)2·C3H6O, consists of two Cu(I) ions bridged by a ferrocene-1,1'-dicarbo-nitrile moiety in a paddle-wheel-architectured sandwich complex with two BF4 (-) units as counter-ions. One of the latter is equally disordered over two sets of sites. The two Cu(I) ions are complexed in a trigonal-planar manner by three nitrile N-donor atoms. Further inter-actions by the O atom of an acetone mol-ecule to one of the Cu(I) atoms and a weak η(2),π-inter-action of two atoms of a cyclo-penta-dienyl ring to the other Cu(I) atom complete a distorted trigonal-pyramidal environment for each of the metal ions. A further acetone mol-ecule is also present as a solvent mol-ecule. The crystal packing is consolidated by several π-π inter-actions.

  9. Crystal structure of bis-{4-bromo-2-[(carb-amim-id-amido-imino)-meth-yl]phenolato-κ(3) N,N',O}cobalt(III) nitrate di-methyl-formamide monosolvate.

    Science.gov (United States)

    Buvaylo, Elena A; Kasyanova, Katerina A; Vassilyeva, Olga Yu; Skelton, Brian W

    2016-07-01

    The title compound, [Co(C8H8BrN4O)2]NO3·C3H7NO, is formed of discrete [CoL 2](+) cations, nitrate anions and di-methyl-formamide (DMF) mol-ecules of crystallization. The cation has no crystallographically imposed symmetry. The ligand mol-ecules are deprotonated at the phenol O atom and octa-hedrally coordinate the Co(III) atoms through the azomethine N and phenolate O atoms in a mer configuration. The deprotonated ligand mol-ecules adopt an almost planar conformation. In the crystal lattice, the cations are arranged in layers in the ab plane divided by the nitrate anions and solvent mol-ecules. No π-π stacking is observed. All of the amine H atoms are involved in hydrogen bonding to nitrate, DMF or ligand O atoms or to one of the Br atoms, forming two-dimensional networks parallel to (100).

  10. Crystal structure of (E)-N-{[3-methyl-1-phenyl-5-(1H-pyrrol-1-yl)-1H-pyrazol-4-yl]methyl-idene}hydroxyl-amine.

    Science.gov (United States)

    Mague, Joel T; Mohamed, Shaaban K; Akkurt, Mehmet; El-Emary, Talaat I; Albayati, Mustafa R

    2014-11-01

    The title compound, C15H14N4O, crystallizes with two mol-ecules in the asymmetric unit with similar conformations (r.m.s. overlay fit for the 20 non-H atoms = 0.175 Å). In the first mol-ecule, the dihedral angles between the planes of the central pyrazole ring and the pendant phenyl and pyrrole rings are 42.69 (8) and 51.88 (6)°, respectively, with corresponding angles of 54.49 (7) and 49.61 (9)°, respectively, in the second mol-ecule. In the crystal, the two mol-ecules, together with their inversion-symmetry counterparts, are linked into tetra-mers by O-H⋯N hydrogen bonds. The tetra-mers form layers parallel to (211) through pairwise C-H⋯π inter-actions.

  11. Crystal structure of 2,3-di-methyl-maleic anhydride: continuous chains of electrostatic attraction.

    Science.gov (United States)

    Wiscons, Ren A; Zeller, Matthias; Rowsell, Jesse L C

    2015-08-01

    In the crystal structure of 2,3-di-methyl-maleic anhydride, C6H6O3, the closest non-bonding inter-molecular distances, between the carbonyl C and O atoms of neighboring mol-ecules, were measured as 2.9054 (11) and 3.0509 (11) Å, which are well below the sum of the van der Waals radii for these atoms. These close contacts, as well as packing motifs similar to that of the title compound, were also found in the crystal structure of maleic anhydride itself and other 2,3-disubstituted maleic anhydrides. Computational modeling suggests that this close contact is caused by strong electrostatic inter-actions between the carbonyl C and O atoms.

  12. Crystal structure of a new hybrid compound based on an iodido-plumbate(II) anionic motif.

    Science.gov (United States)

    Mokhnache, Oualid; Boughzala, Habib

    2016-01-01

    Crystals of the one-dimensional organic-inorganic lead iodide-based compound catena-poly[bis-(piperazine-1,4-diium) [[tetra-iodido-plumbate(II)]-μ-iodido] iodide monohydrate], (C4N2H12)2[PbI5]I·H2O, were obtained by slow evaporation at room temperature of a solution containing lead iodide and piperazine in a 1:2 molar ratio. Inorganic lead iodide chains, organic (C4N2H12)(2+) cations, water mol-ecules of crystallization and isolated I(-) anions are connected through N-H⋯·I, N-H⋯OW and OW-H⋯I hydrogen-bond inter-actions. Zigzag chains of corner-sharing [PbI6](4-) octa-hedra with composition [PbI4/1I2/2](3-) running parallel to the a axis are present in the structure packing.

  13. Redetermination of the crystal structure of 3,5-di-methyl-pyrazolium β-octa-molybdate tetra-hydrate.

    Science.gov (United States)

    Amarante, Tatiana R; Gonçalves, Isabel S; Almeida Paz, Filipe A

    2015-12-01

    The title compound, (C5H9N2)4[Mo8O26]·4H2O, was reported previously from a room-temperature data collection from which only the metal atoms could be refined anisotropically [FitzRoy et al. (1989 ▸). Inorg. Chim. Acta, 157, 187-194]. The current redetermination at 180 (2) K models all the non-H atoms with anisotropic displacement parameters and fully describes the supra-molecular N-H⋯O and O-H⋯O hydrogen-bonded network connecting the 3,5-di-methyl-pyrazolium cations, the water mol-ecules of crystallization and the β-octa-molybdate anion. All H atoms involved in the three-dimensional hydrogen-bonding network could be located from difference Fourier maps, with the exception of those of one disordered water mol-ecule, firstly seen in this structural report [refined over two distinct locations with site-occupancy factors of 0.65 (2) and 0.35 (2)]. The complete β-octa-molybdate anion is generated by a crystallographic inversion centre.

  14. Crystal structure of di-chlorido-(2,2':6',2''-terpyridine-κ(3) N,N',N'')zinc: a redeter-min-ation.

    Science.gov (United States)

    Kong, Cheng-Cheng; Zhou, Jia-Zheng; Yu, Jian-Hua; Li, Sheng-Li

    2014-11-01

    The crystal structure of the title compound, [ZnCl2(C15H11N3)], was redetermined based on modern CCD data. In comparison with the previous determination from photographic film data [Corbridge & Cox (1956 ▶). J. Chem. Soc. 159, 594-603; Einstein & Penfold (1966 ▶). Acta Cryst. 20, 924-926], all non-H atoms were refined with anisotropic displacement parameters, leading to a much higher precision in terms of bond lengths and angles [e.g. Zn-Cl = 2.2684 (8) and 2.2883 (11) compared to 2.25 (1) and 2.27 (1) Å]. In the title mol-ecule, the Zn(II) atom is five-coordinated in a distorted square-pyramidal mode by two Cl atoms and by the three N atoms from the 2,2':6',2''-terpyridine ligand. The latter is not planar and shows dihedral angles between the least-squares planes of the central pyridine ring and the terminal rings of 3.18 (8) and 6.36 (9)°. The mol-ecules in the crystal structure pack with π-π inter-actions [centroid-centroid distance = 3.655 (2) Å] between pyridine rings of neighbouring terpyridine moieties. These, together with inter-molecular C-H⋯Cl inter-actions, stablize the three-dimensional structure.

  15. Crystal structure of (3E)-5-nitro-3-(2-phenyl-hydrazinyl-idene)-1H-indol-2(3H)-one.

    Science.gov (United States)

    Velasques, Jecika Maciel; Gervini, Vanessa Carratu; Bortoluzzi, Adaílton João; de Farias, Renan Lira; de Oliveira, Adriano Bof

    2017-02-01

    The reaction between 5-nitro-isatin and phenyl-hydrazine in acidic ethanol yields the title compound, C14H10N4O3, whose mol-ecular structure deviates slightly from a planar geometry (r.m.s. deviation = 0.065 Å for the mean plane through all non-H atoms). An intra-molecular N-H⋯O hydrogen bond is present, forming a ring of graph-set motif S(6). In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen-bonding inter-actions into a two-dimensional network along (120), and rings of graph-set motif R2(2)(8), R2(2)(26) and R4(4)(32) are observed. Additionally, a Hirshfeld surface analysis suggests that the mol-ecules are stacked along [100] through C=O⋯Cg inter-actions and indicates that the most important contributions for the crystal structure are O⋯H (28.5%) and H⋯H (26.7%) inter-actions. An in silico evaluation of the title compound with the DHFR enzyme (di-hydro-folate reductase) was performed. The isatin-hydrazone derivative and the active site of the selected enzyme show N-H⋯O(ASP29), N-H⋯O(ILE96) and Cg⋯Cg(PHE33) inter-actions.

  16. Crystal structure of 2,2-dimethyl-N-(5-methyl-pyridin-2-yl)propanamide.

    Science.gov (United States)

    El-Hiti, Gamal A; Smith, Keith; Hegazy, Amany S; Alanazi, Saud A; Kariuki, Benson M

    2015-06-01

    There are two mol-ecules in the asymmetric unit of the title compound, C11H16N2O. The pyridine rings and amide groups overlap almost perfectly (r.m.s. overlay fit = 0.053 Å), but the tertiary butyl groups have different orientations: in one mol-ecule, one of the methyl C atoms is syn to the amide O atom [O-C-C-C = -0.8 (3)°] and in the other the equivalent torsion angle is 31.0 (2)°. In the crystal, the two independent mol-ecules are linked by a pair of N-H⋯N hydrogen bonds in the form of an R 2 (2)(8) loop to form a dimer. A C-H⋯O inter-action connects the dimers into [100] chains.

  17. Crystal structure of O-benzyl-l-tyrosine N-carb-oxy anhydride.

    Science.gov (United States)

    Inada, Aya; Kanazawa, Hitoshi

    2017-04-01

    In the title compound, C17H15NO4 (alternative name; O-benzyl-l-tyrosine N-carb-oxy anhydride), the oxazolidine ring is planer, with an r.m.s. deviation of 0.039 Å. The benz-yloxy and benzyl rings are almost coplanar, making a dihedral angle of 0.078 (10)°, and are inclined to the oxazolidine ring by 59.16 (11) and 58.42 (11)°, respectively. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming ribbons propagating along [010]. The ribbons are linked by C-H⋯π inter-actions, forming a three-dimensional supra-molecular structure. The oxazolidine rings of adjacent ribbons are arranged into a layer parallel to the ab plane. This arrangement is favourable for the polymerization of the compound in the solid state.

  18. Crystal structure of [(1,2,3,4,11,12-η)-anthracene]tris-(tri-methyl-stann-yl)cobalt(III).

    Science.gov (United States)

    Brennessel, William W; Ellis, John E

    2014-11-01

    The asymmetric unit of the title structure, [Co(η(6)-C14H10){Sn(CH3)3}3], contains two independent mol-ecules. Each anthracene ligand is η(6)-coordinating to a Co(III) cation and is nearly planar [fold angles of 5.4 (3) and 9.7 (3)°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co-C bond lengths to the ring junction carbon atoms than to the other four. Each Co(III) cation is further coordinated by three Sn(CH3)3 ligands, giving each mol-ecule a three-legged piano-stool geometry. In each of the two independent mol-ecules, the trio of SnMe3 ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one mol-ecule, the disorder ratio refined to 0.9365 (8):0.0635 (8), while that for the other refined to 0.9686 (8):0.0314 (8). The mol-ecules are well separated, and thus no significant inter-molecular inter-actions are observed. The compound is of inter-est as the first structure report of an η(6)-anthracene cobalt(III) complex.

  19. Crystal structure of benzyl (E)-2-(3,4-di-meth-oxy-benzyl-idene)hydrazine-1-carbodi-thio-ate.

    Science.gov (United States)

    Tan, Yew-Fung; Break, Mohammed Khaled Bin; Tahir, M Ibrahim M; Khoo, Teng-Jin

    2015-02-01

    The title compound, C17H18N2O2S2, synthesized via a condensation reaction between S-benzyl di-thio-carbazate and 3,4-di-meth-oxy-benzaldehyde, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. Both mol-ecules have an L-shape but differ in the orientation of the benzyl ring with respect to the 3,4-di-meth-oxy-benzyl-idine ring, this dihedral angle is 65.59 (8)° in mol-ecule A and 73.10 (8)° in mol-ecule B. In the crystal, the A and B mol-ecules are linked via pairs of N-H⋯S hydrogen bonds, forming dimers with an R 2 (2)(8) ring motif. The dimers are linked via pairs of C-H⋯O hydrogen bonds, giving inversion dimers of dimers. These units are linked by C-H⋯π inter-actions, forming ribbons propagating in the [100] direction.

  20. Crystal structures of three 6-substituted coumarin-3-carboxamide derivatives.

    Science.gov (United States)

    Gomes, Lígia R; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, Fernanda

    2016-07-01

    Three coumarin derivatives, viz. 6-methyl-N-(3-methyl-phen-yl)-2-oxo-2H-chromene-3-carboxamide, C18H15NO3 (1), N-(3-meth-oxy-phen-yl)-6-methyl-2-oxo-2H-chromene-3-carboxamide, C18H15NO4 (2), and 6-meth-oxy-N-(3-meth-oxy-phen-yl)-2-oxo-2H-chromene-3-carboxamide, C18H15NO5 (3), were synthesized and structurally characterized. The mol-ecules display intra-molecular N-H⋯O and weak C-H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol-ecules. The supra-molecular structures feature C-H⋯O hydrogen bonds and π-π inter-actions, as confirmed by Hirshfeld surface analyses.

  1. Crystal structure of bis-(2,2'-bi-pyridine-κ(2) N,N')bis-(thio-cyanato-κN)mang-anese(II) 2,2'-bi-pyridine monosolvate.

    Science.gov (United States)

    Suckert, Stefan; Jess, Inke; Näther, Christian

    2015-01-01

    In the crystal structure of the mononuclear title compound, [Mn(NCS)2(C10H8N2)2]·C10H8N2, the Mn(II) cation is coordin-ated in an all-cis configuration by two N-bound thio-cyanate anions and two 2,2'-bi-pyridine ligands within a slightly distorted octa-hedral environment. The asymmetric unit consists of one Mn(II) cation, two thio-cyanate anions and two 2,2'-bi-pyridine ligands, as well as two non-coordinating 2,2'-bi-pyridine ligands that are each located on centres of inversion. In the crystal structure, the discrete [Mn(NCS)2(C10H8N2)2] complex mol-ecules are arranged in such a way that cavities are formed, in which the solvent 2,2'-bi-pyridine mol-ecules are located. Apart from van der Waals forces, there are no remarkable inter-molecular inter-actions present in the crystal structure.

  2. Mol-ecular and crystal structure of gossypol tetra-methyl ether with an unknown solvate.

    Science.gov (United States)

    Honkeldieva, Muhabbat; Talipov, Samat; Mardanov, Rustam; Ibragimov, Bakhtiyar

    2015-02-01

    The title compound, C34H38O8 (systematic name: 5,5'-diisopropyl-2,2',3,3'-tetra-meth-oxy-7,7'-dimethyl-2H,2'H-8,8'-bi-[naphtho-[1,8-bc]furan]-4,4'-diol), has been obtained from a gossypol solution in a mixture of dimethyl sulfate and methanol. The mol-ecule is situated on a twofold rotation axis, so the asymmetric unit contains one half-mol-ecule. In the mol-ecule, the hy-droxy groups are involved in intra-molecular O-H⋯O hydrogen bonds, and the two naphthyl fragments are inclined each to other by 83.8 (1)°. In the crystal, weak C-H⋯O and C-H⋯π inter-actions consolidate the packing, which exhibits channels with an approximate diameter of 6 Å extending along the c-axis direction. These channels are filled with highly disordered solvent mol-ecules, so their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE option in PLATON [Spek, A. L. (2015). Acta Cryst. C71, 9-18].

  3. Crystal structure of 1,1'-{(pentane-1,5-di-yl)bis[(aza-niumylyl-idene)methanylyl-idene]}bis(naphthalen-2-olate).

    Science.gov (United States)

    Ouari, Kamel; Merzougui, Moufida; Karmazin, Lydia

    2015-09-01

    The whole mol-ecule of the title compound, C27H26N2O2, is generated by twofold rotational symmetry, with the central C atom of the pentyl chain located on the twofold rotation axis. The compound crystallizes as a bis-zwitterion, and there are two intra-molecular N-H⋯O hydrogen bonds generating S(6) ring motifs. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming ribbons propagating along [001], and enclosing R 2 (2)(22) ring motifs.

  4. Crystal structure of bis-(3-bromo-pyridine-κN)bis-(O-ethyl di-thio-carbonato-κ(2) S,S')nickel(II).

    Science.gov (United States)

    Kant, Rajni; Kour, Gurvinder; Anthal, Sumati; Neerupama; Sachar, Renu

    2015-01-01

    In the title mol-ecular complex, [Ni(C3H5OS2)2(C5H4BrN)2], the Ni(2+) cation is located on a centre of inversion and has a distorted octa-hedral N2S4 environment defined by two chelating xanthate ligands and two monodentate pyridine ligands. The C-S bond lengths of the thio-carboxyl-ate group are indicative of a delocalized bond and the O-Csp (2) bond is considerably shorter than the O-Csp (3) bond, consistent with a significant contribution of one resonance form of the xanthate anion that features a formal C=O+ unit and a negative charge on each of the S atoms. The packing of the mol-ecules is stabilized by C-H⋯S and C-H⋯π inter-actions. In addition, π-π inter-actions between the pyridine rings [centroid-to-centroid distance = 3.797 (3) Å] are also present. In the crystal structure, mol-ecules are arranged in rows along [100], forming layers parallel to (010) and (001).

  5. Crystal structures of two mononuclear complexes of terbium(III) nitrate with the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane.

    Science.gov (United States)

    Gregório, Thaiane; Giese, Siddhartha O K; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2017-02-01

    Two new mononuclear cationic complexes in which the Tb(III) ion is bis-chelated by the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane (H3L(Et), C6H14O3) were prepared from Tb(NO3)3·5H2O and had their crystal and mol-ecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) nitrate di-meth-oxy-ethane hemisolvate, [Tb(NO3)2(H3L(Et))2]NO3·0.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-anti-prismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-mol-ecule of di-meth-oxy-ethane (completed by a crystallographic twofold rotation axis) is also present. In product aqua-nitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) dinitrate, [Tb(NO3)(H3L(Et))2(H2O)](NO3)2, 2, one bidentate nitrate ion and one water mol-ecule are bound to the nine-coordinate terbium(III) centre, while two free nitrate ions contribute to charge balance outside the tricapped trigonal-prismatic coordination polyhedron. No free water mol-ecule was found in either of the crystal structures and, only in the case of 1, di-meth-oxy-ethane acts as a crystallizing solvent. In both mol-ecular structures, the two tripodal ligands are bent to one side of the coordination sphere, leaving room for the anionic and water ligands. In complex 2, the methyl group of one of the H3L(Et) ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and inter-molecular, are found in the crystal structures due to the number of different donor and acceptor groups present.

  6. Crystal structure of [propane-1,3-diylbis(piperidine-4,1-di-yl)]bis-[(pyridin-4-yl)methanone]-isophthalic acid (1/1).

    Science.gov (United States)

    Murray, Nathan H; Biros, Shannon M; LaDuca, Robert L

    2014-11-01

    In the crystal structure of the title co-crystal, C25H32N4O2·C8H6O4, isophthalic acid and [propane-1,3-diylbis(piperidine-4,1-di-yl)]bis-(pyridin-4-yl-methanone) mol-ecules are connected into supra-molecular chains aligned along the c axis by O-H⋯N hydrogen bonding. These aggregate into supra-molecular layers oriented parallel to the ac plane by C-H⋯O inter-actions. These layers then stack in an ABCD pattern along the b-axis direction by additional C-H⋯O inter-actions to give the full three-dimensional crystal structure. The central chain in the di-pyridyl-amide molecule has an anti-gauche conformation.

  7. Crystal structures of the two salts 2-methyl-1H-imidazol-3-ium nitrate-2-methyl-1H-imidazole (1/1) and 2-methyl-1H-imidazol-3-ium nitrate.

    Science.gov (United States)

    Diop, Mouhamadou Birame; Diop, Libasse; Maris, Thierry

    2016-04-01

    The title salts, C4H7N2 (+)·NO3 (-)·C4H6N2, (I), and C4H7N2 (+)·NO3 (-), (II), were obtained from solutions containing 2-methyl-imidazole and nitric acid in different concentrations. In the crystal structure of salt (I), one of the -NH H atoms of the imidazole ring shows half-occupancy, hence only every second mol-ecule is in its cationic form. The nitrate anion in this structure lies on a twofold rotation axis. The neutral 2-methyl-imidazole mol-ecule and the 2-methyl-1H-imidazol-3-ium cation inter-act through N-H⋯N hydrogen bonds to form [(C4H6N2)⋯(C4H7N2)(+)] pairs. These pairs are linked with two nitrate anions on both sides through bifurcated N-H⋯(O,O) hydrogen bonds into chains running parallel to [001]. In the crystal structure of salt (II), the C4H7N2 (+) cation and the NO3 (-) anion are both located on a mirror plane, leading to a statistical disorder of the methyl H atoms. The cations and anions again inter-act through bifurcated N-H⋯(O,O) hydrogen bonds, giving rise to the formation of chains consisting of alternating anions and cations parallel to [100].

  8. Crystal structure of zwitterionic 3-(2-hy-droxy-2-phospho-nato-2-phosphono-eth-yl)imidazo[1,2-a]pyridin-1-ium monohydrate (minodronic acid monohydrate): a redetermination.

    Science.gov (United States)

    Airoldi, Annalisa; Bettoni, Piergiorgio; Donnola, Monica; Calestani, Gianluca; Rizzoli, Corrado

    2015-01-01

    In a previous study, the X-ray structure of the title compound, C9H12N2O7P2·H2O, was reported [Takeuchi et al., (1998 ▶). Chem. Pharm. Bull. 46, 1703-1709], but neither atomic coordinates nor details of the geometry were published. The structure has been redetermined with high precision as its detailed knowledge is essential to elucidate the presumed polymorphism of minodronic acid monohydrate at room temperature. The mol-ecule crystallizes in a zwitterionic form with cationic imidazolium[1,2a]pyridine and anionic phospho-nate groups. The dihedral angle formed by the planes of the pyridine and imidazole rings is 3.55 (9)°. A short intra-molecular C-H⋯O contact is present. In the crystal, mol-ecules are linked by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds and π-π inter-actions [centroid-to-centroid distance = 3.5822 (11) Å], forming a three-dimensional structure.

  9. Crystal structure of dimethyl 2-((2Z,5Z)-5-(2-meth-oxy-2-oxo-ethyl-idene)-2-{(E)-[2-methyl-5-(prop-1-en-2-yl)cyclo-hex-2-enyl-idene]hydrazinyl-idene}-4-oxo-thia-zolidin-3-yl)fumarate.

    Science.gov (United States)

    N'ait Ousidi, Abdellah; Ait Itto, My Youssef; Auhmani, Aziz; Riahi, Abdelkhalek; Auhmani, Abdelwahed; Daran, Jean-Claude

    2017-02-01

    The crystal structure and the conformation of the title compound, C22H27N3O7S, were determined from the synthetic pathway and by X-ray analysis. This compound is a new 4-thia-zolidinone derivative prepared and isolated as pure product from thio-semicarbazone carvone. The mol-ecule is built up from an oxo-thia-zolidine ring tetra-substituted by a meth-oxy-oxo-ethyl-idene, a maleate, an oxygen and a cyclo-hexyl-idene-hydrazone. The cyclo-hexyl-idene ring is statistically disordered over two positions, resulting in an inversion of configuration for the substituted carbon.

  10. Crystal structure of 4-(3-carb-oxy-pro-pan-amido)-2-hy-droxy-benzoic acid mono-hydrate.

    Science.gov (United States)

    Tahir, Muhammad Nawaz; Ahmed, Muhammad Naeem; Butt, Arshad Farooq; Shad, Hazoor Ahmad

    2014-12-01

    In the title hydrate, C11H11NO6·H2O, the organic mol-ecule is approximately planar (r.m.s. deviation for the non-H atoms = 0.129 Å) and an intra-molecular O-H⋯O hydrogen bond closes an S(6) ring. In the crystal, the benzoic acid group participates in an O-H⋯O hydrogen bond to the water mol-ecule and accepts a similar bond from another water mol-ecule. The other -CO2H group forms a carb-oxy-lic acid inversion dimer, thereby forming an R 2 (2)(8) loop. These bonds, along with N-H⋯O and C-H⋯O inter-actions, generate a three-dimensional network.

  11. Crystal structures of deuterated sodium molybdate dihydrate and sodium tungstate dihydrate from time-of-flight neutron powder diffraction.

    Science.gov (United States)

    Fortes, A Dominic

    2015-07-01

    Time-of-flight neutron powder diffraction data have been measured from ∼90 mol% deuterated isotopologues of Na2MoO4·2H2O and Na2WO4·2H2O at 295 K to a resolution of sin (θ)/λ = 0.77 Å(-1). The use of neutrons has allowed refinement of structural parameters with a precision that varies by a factor of two from the heaviest to the lightest atoms; this contrasts with the X-ray based refinements where precision may be > 20× poorer for O atoms in the presence of atoms such as Mo and W. The accuracy and precision of inter-atomic distances and angles are in excellent agreement with recent X-ray single-crystal structure refinements whilst also completing our view of the hydrogen-bond geometry to the same degree of statistical certainty. The two structures are isotypic, space-group Pbca, with all atoms occupying general positions, being comprised of edge- and corner-sharing NaO5 and NaO6 polyhedra that form layers parallel with (010) inter-leaved with planes of XO4 (X = Mo, W) tetra-hedra that are linked by chains of water mol-ecules along [100] and [001]. The complete structure is identical with the previously described molybdate [Capitelli et al. (2006 ▸). Asian J. Chem. 18, 2856-2860] but shows that the purported three-centred inter-action involving one of the water mol-ecules in the tungstate [Farrugia (2007 ▸). Acta Cryst. E63, i142] is in fact an ordinary two-centred 'linear' hydrogen bond.

  12. Crystal structure of N,N,N',N',N'',N''-hexa-methyl-guanidinium cyanate 1.5-hydrate.

    Science.gov (United States)

    Tiritiris, Ioannis; Kantlehner, Willi

    2015-12-01

    The title hydrated salt, C7H18N3 (+)·OCN(-).1.5H2O, was synthesized starting from N,N,N',N',N'',N''-hexa-methyl-guanidinium chloride by a twofold anion-exchange reaction. The asymmetric unit contains two cations, two cyanate anions and three water mol-ecules. One cation shows orientational disorder and two sets of N-atom positions were found related by a 60° rotation, with an occupancy ratio of 0.852 (6):0.148 (6). The C-N bond lengths in both guanidin-ium ions range from 1.329 (2) to 1.358 (10) Å, indicating double-bond character, pointing towards charge delocalization within the NCN planes. Strong O-H⋯N hydrogen bonds between the crystal water mol-ecules and the cyanate ions and strong O-H⋯O hydrogen bonds between the water mol-ecules are present, resulting in a two-dimensional hydrogen bonded network running parallel to the (001) plane. The hexa-methyl-guanidinium ions are packed in between the layers built up by water mol-ecules and cyanate ions.

  13. Crystal structure of 7,7-dimethyl-6-methyl-idenetri-cyclo-[6.2.1.0(1,5)]undecane-2-carb-oxy-lic acid.

    Science.gov (United States)

    Beghidja, Noureddine; Benayache, Samir; Benayache, Fadila; Knight, David W; Kariuki, Benson M

    2015-02-01

    In the title compound, C15H22O2, both five-membered rings display an envelope conformation whereas the six-membered ring displays a chair conformation. In the crystal, pairs of O-H⋯O hydrogen bonds between carb-oxy-lic groups link mol-ecules, related by a twofold rotation axis, into supra-molecular dimers.

  14. Crystal structure of a layered coordination polymer based on a 4(4) net containing Cd(2+) ions and 1,5-bis-(pyridin-4-yl)pentane linkers.

    Science.gov (United States)

    Harrison, William T A; Plater, M John; deSilva, Ben M deSilva; Foreman, Mark R St J

    2014-08-01

    The title compound, poly[[di-aqua-bis-[1,5-bis-(pyridin-4-yl)pentane-κ(2) N:N']cadmium] bis-(perchlorate) 1,5-bis-(pyridin-4-yl)pentane ethanol mono-solvate], [Cd(C15H18N2)2(H2O)2](ClO4)2·C15H18N2·C2H6O, is a layered coordination polymer built up from highly squashed 4(4) nets in which the octa-hedral trans-CdO2N4 nodes (Cd site symmetry -1) are linked by the bifunctional ligands, forming infinite (110) sheets. The cationic sheets are charge-balanced by inter-layer perchlorate ions. A free 1,5-bis-(pyridin-4-yl)pentane mol-ecule and an ethanol mol-ecule of crystallization are also found in the inter-sheet region. A number of O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds help to consolidate the layered structure.

  15. Crystal structure of (μ-1,4-di-carb-oxy-butane-1,4-di-carboxyl-ato)bis-[bis-(tri-phenyl-phosphane)silver(I)] di-chloro-methane tris-olvate.

    Science.gov (United States)

    Frenzel, Peter; Korb, Marcus; Lang, Heinrich

    2016-02-01

    The mol-ecular structure of the tetra-kis(tri-phenyl-phosphan-yl)disilver salt of butane-1,1,4,4-tetra-carb-oxy-lic acid, [Ag2(C8H8O8)(C18H15P)4]·3CH2Cl2, crystallizes with one and a half mol-ecules of di-chloro-methane in the asymmetric unit. The coordination complex exhibits an inversion centre through the central CH2-CH2 bond. The Ag(I) atom has a distorted trigonal-planar P2O coordination environment. The packing is characterized by inter-molecular T-shaped π-π inter-actions between the phenyl rings of the PPh3 substituents in neighbouring mol-ecules, forming a ladder-type superstructure parallel to [010]. These ladders are arranged in layers parallel to (101). Intra-molecular hydrogen bonds between the OH group and one O atom of the Ag-bonded carboxyl-ate group results in an asymmetric bidendate coordination of the carboxyl-ate moiety to the Ag(I) ion.

  16. Crystal structure of ({(1R,2R)-N,N'-bis-[(quino-lin-2-yl)methyl]cyclo-hexane-1,2-di-amine}-chlorido-iron(III))-μ-oxido-[tri-chlorido-ferrate(III)] chloro-form monosolvate.

    Science.gov (United States)

    Swift, Hannah; Carrig, Molly W; Oshin, Kayode D; Vinokur, Anastasiya I; Desper, John A; Levy, Christopher J

    2017-07-01

    The first Fe(III) atom in the solvated title compound, [Fe2Cl4O(C26H28N4)]·CHCl3, adopts a distorted six-coordinate octa-hedral geometry. It is coordinated by one chloride ligand, four N atoms from the (1R,2R)-N,N'-bis-[(quinolin-2-yl)methyl]cyclo-hexane-1,2-di-amine ligand, and a bridging oxido ligand attached to the second Fe(III) atom, which is also bonded to three chloride ions. A very weak intra-molecular N-H⋯Cl hydrogen bond occurs. In the crystal, the coordination complexes stack in columns, and a grouping of six such columns create channels, which are populated by disordered chloro-form solvent mol-ecules. Although the Fe-Cl bond lengths for the two metal atoms are comparable to the mean Fe-Cl bond lengths as derived from the Cambridge Structural Database, the Fe-O bond lengths are notably shorter. The solvent chloro-form mol-ecule exhibits 'flip' disorder of the C-H moiety in a 0.544 (3):0.456 (3) ratio. The only directional inter-action noted is a weak C-H⋯Cl hydrogen bond.

  17. Crystal structure of 3,4-di-meth-oxy-phenol.

    Science.gov (United States)

    Mills-Robles, Heather A; Desikan, Vasumathi; Golen, James A; Manke, David R

    2015-12-01

    The title compound, C8H10O3, has two planar mol-ecules in the asymmetric unit possessing mean deviations from planarity of 0.051 and 0.071 Å. In the crystal, there are two distinct infinite chains, both along [010]. The chains are formed by O-H⋯O inter-actions between the phenol and both the 3-meth-oxy and the 4-meth-oxy groups.

  18. Crystal structure of 4-meth-oxy-quinazoline.

    Science.gov (United States)

    El-Hiti, Gamal A; Smith, Keith; Hegazy, Amany S; Alshammari, Mohammed B; Kariuki, Benson M

    2014-12-01

    The title compound, C9H8N2O, is almost planar, with the C atom of the meth-oxy group deviating from the mean plane of the quinazoline ring system (r.m.s. deviation = 0.011 Å) by 0.068 (4) Å. In the crystal, mol-ecules form π-π stacks parallel to the b-axis direction [centroid-centroid separation = 3.5140 (18) Å], leading to a herringbone packing arrangement.

  19. Crystal structure of 2-[(di-chloro-methane)sulfon-yl]pyridine.

    Science.gov (United States)

    Chen, Zhiqiu; Bolat, Hembat; Wan, Xing; Li, Ya

    2014-12-01

    The asymmetric unit of the title compound, C6H5Cl2NO2S, contains two mol-ecules with similar conformations (r.m.s. overlay fit for the non-H atoms = 0.067 Å). Atoms attached to the pendent Csp (3)-S bond are arranged in a staggered conformation with one of the Cl atoms anti to the C atom in the aromatic ring [C-S-C-Cl torsion angles = 178.41 (11) and -176.70 (13)°]. In the crystal, mol-ecules are linked by C-H⋯N and C-H⋯O hydrogen bonds, generating a three-dimensional network, and weak aromatic π-π stacking is also observed [centroid-centroid separation = 3.8902 (17) Å].

  20. Crystal structure of 6-amino-4-(3-bromo-4-meth-oxy-phen-yl)-3-methyl-2,4-di-hydro-pyrano[2,3-c]pyrazole-5-carbo-nitrile dimethyl sulfoxide monosolvate.

    Science.gov (United States)

    Yousuf, Sammer; Bano, Huma; Muhammad, Munira Taj; Khan, Khalid Mohammed

    2015-07-01

    In the pyrazole mol-ecule of the title solvate, C15H13BrN4O2·C2H6OS, the dihedral angle between the benzene ring and the mean plane of the di-hydro-pyrano[2,3-c]pyrazole ring system [r.m.s deviation = 0.031 (2) Å] is 86.71 (14)°. In the crystal, the pyrazole mol-ecules are linked by N-H⋯N hydrogen bonds, forming a layer parallel to (10-1). The pyrazole and dimethyl sulfoxide mol-ecules are connected by an N-H⋯O hydrogen bond.

  1. Crystal structure of N-(tert-but-oxy-carbon-yl)phenyl-alanylde-hydro-alanine isopropyl ester (Boc-Phe-ΔAla-OiPr).

    Science.gov (United States)

    Lenartowicz, Paweł; Makowski, Maciej; Zarychta, Bartosz; Ejsmont, Krzysztof

    2014-12-01

    In the title compound, the de-hydro-dipeptide (Boc-Phe-ΔAla-OiPr, C20H28N2O5), the mol-ecule has a trans conformation of the N-methyl-amide group. The geometry of the de-hydro-alanine moiety is to some extent different from those usually found in simple peptides, indicating conjugation between the H2C=C group and the peptide bond. The bond angles around de-hydro-alanine have unusually high values due to the steric hindrance, the same inter-action influencing the slight distortion from planarity of the de-hydro-alanine. The mol-ecule is stabilized by intra-molecular inter-actions between the isopropyl group and the N atoms of the peptide main chain. In the crystal, an N-H⋯O hydrogen bond links the mol-ecules into ribbons, giving a herringbone head-to-head packing arrangement extending along the [100] direction. In the stacks, the mol-ecules are linked by weak C-H⋯O hydrogen-bonding associations.

  2. Crystal structures of two mixed-valence copper cyanide complexes with N-methyl-ethylenedi-amine.

    Science.gov (United States)

    Corfield, Peter W R; Sabatino, Alexander

    2017-02-01

    The crystal structures of two mixed-valence copper cyanide compounds involving N-methyl-ethylenedi-amine (meen), are described. In compound (I), poly[bis(μ3-cyanido-κ3C:C:N)tris(μ2-cyanido-κ2C:N)bis(N-methylethane-1,2-di-amine-κ2N,N')tricopper(I)copper(II)], [Cu4(CN)5(C3H10N2)2] or Cu4(CN)5meen2, cyanide groups link Cu(I) atoms into a three-dimensional network containing open channels parallel to the b axis. In the network, two tetra-hedrally bound Cu(I) atoms are bonded by the C atoms of two end-on bridging CN groups to form Cu2(CN)6 moieties with the Cu atoms in close contact at 2.560 (1) Å. Other trigonally bound Cu(I) atoms link these units together to form the network. The Cu(II) atoms, coordinated by two meen units, are covalently linked to the network via a cyanide bridge, and project into the open network channels. In the mol-ecular compound (II), [(N-methylethylenediamine-κ(2)N,N')copper(II)]-μ(2)-cyanido-κ(2)C:N-[bis(cyanido-κC)copper(I)] monohydrate, [Cu2(CN)3(C3H10N2)2]·H2O or Cu2(CN)3meen2·H2O, a CN group connects a Cu(II) atom coordinated by two meen groups with a trigonal-planar Cu(I) atom coordinated by CN groups. The mol-ecules are linked into centrosymmetric dimers via hydrogen bonds to two water mol-ecules. In both compounds, the bridging cyanide between the Cu(II) and Cu(I) atoms has the N atom bonded to Cu(II) and the C atom bonded to Cu(I), and the Cu(II) atoms are in a square-pyramidal coordination.

  3. Crystal structure of catena-poly[[di-aqua-cobalt(II)]-bis-[μ-5-(4-carb-oxy-ylato-phenyl)picolinato]-κ(3) N,O (2):O (5);κ(3) O (5):N,O (2)-[di-aqua-cobalt(II)]-μ-1-[4-(1H-imidazol-1-yl)phen-yl]-1H-imidazole-κ(2) N (3):N (3')].

    Science.gov (United States)

    Xu, Guo-Wang; Wang, Ye-Nan; Wang, Hai-Bing; Wang, Zhong-Long

    2015-07-01

    The asymmetric unit of the title polymeric Co(II) complex, [Co2(C13H7NO4)2(C12H10N4)(H2O)4] n , contains a Co(II) cation, a 5-(4-carboxyl-atophen-yl)picolinate dianion, two coordination water mol-ecules and half of 1-[4-(1H-imidazol-1-yl)phen-yl]-1H-imidazole ligand. The Co(II) cation is coordinated by two picolinate dianions, two water mol-ecules and one 1-[4-(1H-imidazol-1-yl)phen-yl]-1H-imidazole mol-ecule in a distorted N2O4 octa-hedral coordination geometry. The two picolinate dianions are related by an inversion centre and link two Co(II) cations, forming a binuclear unit, which is further bridged by the imidazole mol-ecules, located about an inversion centre, into the polymeric chain propagating along the [-1-11] direction. In the crystal, the three-dimensional supra-molecular architecture is constructed by O-H⋯O hydrogen bonds between the coordinating water mol-ecules and the non-coordinating carboxyl-ate O atoms of adjacent polymeric chains.

  4. Crystal structure of γ-methyl l-glutamate N-carb-oxy anhydride.

    Science.gov (United States)

    Kanazawa, Hitoshi; Inada, Aya; Sakon, Aya; Uekusa, Hidehiro

    2015-01-01

    In the title compound, C7H9NO5, alternative name N-carb-oxy-l-glutamic anhydride γ-methyl ester, the oxazolidine ring is essentially planar with a maximum deviation of 0.020 (3) Å. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the methyl ester group, forming a tape structure along the a-axis direction. The tapes are linked by C-H⋯O inter-actions into a sheet parallel to the ac plane. The tapes are also stacked along the b axis with short contacts between the oxazolidine rings [C⋯O contact distances = 2.808 (4)-3.060 (4) Å], so that the oxazolidine rings are arranged in a layer parallel to the ab plane. This arrangement of the oxazolidine rings is very preferable for the polymerization of the title compound in the solid state.

  5. 2-({[(Pyridin-1-ium-2-ylmeth-yl)carbamo-yl]form-amido}-meth-yl)pyridin-1-ium bis-(3,5-di-carb-oxy-benzoate): crystal structure and Hirshfeld surface analysis.

    Science.gov (United States)

    Jotani, Mukesh M; Syed, Sabrina; Halim, Siti Nadiah Abdul; Tiekink, Edward R T

    2016-02-01

    The asymmetric unit of the title salt, C14H16N4O2 (2+)·2C9H5O6 (-), comprises half a dication, being located about a centre of inversion, and one anion, in a general position. The central C4N2O2 group of atoms in the dication are almost planar (r.m.s. deviation = 0.009 Å), and the carbonyl groups lie in an anti disposition to enable the formation of intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds. To a first approximation, the pyridinium and amide N atoms lie to the same side of the mol-ecule [Npy-C-C-Namide torsion angle = 34.8 (2)°], and the anti pyridinium rings are approximately perpendicular to the central part of the mol-ecule [dihedral angle = 68.21 (8)°]. In the anion, one carboxyl-ate group is almost coplanar with the ring to which it is connected [Cben-Cben-Cq-O torsion angle = 2.0 (3)°], whereas the other carboxyl-ate and carb-oxy-lic acid groups are twisted out of the plane [torsion angles = 16.4 (3) and 15.3 (3)°, respectively]. In the crystal, anions assemble into layers parallel to (10-4) via hy-droxy-O-H⋯O(carbon-yl) and charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) hydrogen bonds. The dications are linked into supra-molecular tapes by amide-N-H⋯O(amide) hydrogen bonds, and thread through the voids in the anionic layers, being connected by charge-assisted pyridinium-N-O(carboxyl-ate) hydrogen bonds, so that a three-dimensional architecture ensues. An analysis of the Hirshfeld surface points to the importance of O-H⋯O hydrogen bonding in the crystal structure.

  6. Crystal structure of an unknown solvate of (piperazine-κN){5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato-κ(4) N}zinc.

    Science.gov (United States)

    Nasri, Soumaya; Ezzayani, Khaireddine; Turowska-Tyrk, Ilona; Roisnel, Thierry; Nasri, Habib

    2016-07-01

    The title compound, [Zn(C72H44N4O8)(C4H10N2)] or [Zn(TPBP)(pipz] (where TPBP and pipz are 5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordin-ation geometry about the central Zn(II) atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitro-gen atom of the piperazine axial ligand, which adopts a chair confirmation. The average Zn-N(pyrrole) bond length is 2.078 (7) Å and the Zn- N(pipz) bond length is 2.1274 (19) Å. The zinc cation is displaced by 0.4365 (4) Å from the N4C20 mean plane of the porphyrinate anion toward the piperazine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling deformations. In the crystal, the supra-molecular structure is made by parallel pairs of layers along (100), with an inter-layer distance of 4.100 Å while the distance between two pairs of layers is 4.047 Å. A region of electron density was treated with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON following unsuccessful attempts to model it as being part of disordered n-hexane solvent and water mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules.

  7. Crystal structures of N(2),N(3),N(5),N(6)-tetra-kis-(pyridin-2-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide and N(2),N(3),N(5),N(6)-tetra-kis-(pyridin-4-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide.

    Science.gov (United States)

    Cati, Dilovan S; Stoeckli-Evans, Helen

    2017-02-01

    The title compounds, C32H28N10O4· unknown solvent, (I), and C32H28N10O4, (II), are pyrazine-2,3,5,6-tetra-carboxamide derivatives. In (I), the substituents are (pyridin-2-ylmeth-yl)carboxamide, while in (II), the substituents are (pyridin-4-ylmeth-yl)carboxamide. Both compounds crystallize in the monoclinic space group P21/n, with Z' = 1 for (I), and Z' = 0.5 for (II). The whole mol-ecule of (II) is generated by inversion symmetry, the pyrazine ring being situated about a center of inversion. In (I), the four pyridine rings are inclined to the pyrazine ring by 83.9 (2), 82.16 (18), 82.73 (19) and 17.65 (19)°. This last dihedral angle involves a pyridine ring that is linked to the adjacent carboxamide O atom by an intra-molecular C-H⋯O hydrogen bond. In compound (II), the unique pyridine rings are inclined to the pyrazine ring by 33.3 (3) and 81.71 (10)°. There are two symmetrical intra-molecular C-H⋯O hydrogen bonds present in (II). In the crystal of (I), mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming layers parallel to (10-1). The layers are linked by C-H⋯O and C-H⋯N hydrogen bonds, forming a three-dimensional framework. In the crystal of (II), mol-ecules are linked by N-H⋯N hydrogen bonds, forming chains propagating along the [010] direction. The chains are linked by a weaker N-H⋯N hydrogen bond, forming layers parallel to the (101) plane, which are in turn linked by C-H⋯O hydrogen bonds, forming a three-dimensional structure. In the crystal of compound (I), a region of disordered electron density was treated with the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. Their contribution was not taken into account during refinement. In compound (II), one of the pyridine rings is positionally disordered, and the refined occupancy ratio for the disordered Car-Car-Npy atoms is 0.58 (3):0.42 (3).

  8. Crystal structure of catena-poly[[(dimethyl sulfoxide-κO)(pyridine-2,6-di-carboxyl-ato-κ(3) O,N,O')nickel(II)]-μ-pyrazine-κ(2) N:N'].

    Science.gov (United States)

    Liu, Chen; Thuijs, Annaliese E; Felts, Ashley C; Ballouk, Hamza F; Abboud, Khalil A

    2016-05-01

    The title coordination polymer, [Ni(C7H3NO4)(C4H4N2)(C2H6OS)] n , consists of [010] chains composed of Ni(II) ions linked by bis-monodentate-bridging pyrazine mol-ecules. Each of the two crystallographically distinct Ni(II) ions is located on a mirror plane and is additionally coordinated by a dimethyl sulfoxide (DMSO) ligand through the oxygen atom and by a tridentate 2,6-pyridine-di-carb-oxy-lic acid dianion through one of each of the carboxyl-ate oxygen atoms and the pyridine nitro-gen atom, leading to a distorted octa-hedral coordination environment. The title structure exhibits an inter-esting complementarity between coordinative bonding and π-π stacking where the Ni-Ni distance of 7.0296 (4) Å across bridging pyrazine ligands allows the pyridine moieties on two adjacent chains to inter-digitate at halfway of the Ni-Ni distance, resulting in π-π stacking between pyridine moieties with a centroid-to-plane distance of 3.5148 (2) Å. The double-chain thus formed also exhibits C-H⋯π inter-actions between pyridine C-H groups on one chain and pyrazine mol-ecules on the other chain. As a result, the inter-ior of the double-chain structure is dominated by π-π stacking and C-H⋯ π inter-actions, while the space between the double-chains is occupied by a C-H⋯O hydrogen-bonding network involving DMSO ligands and carboxyl-ate groups located on the exterior of the double-chains. This separation of dissimilar inter-actions in the inter-ior and exterior of the double-chains further stabilizes the crystal structure.

  9. Crystal structures of 3-fluoro-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide, 3-bromo-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide and 3-iodo-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide.

    Science.gov (United States)

    Suchetan, P A; Suresha, E; Naveen, S; Lokanath, N K

    2016-06-01

    In the title compounds, C14H9F4NO, (I), C14H9BrF3NO, (II), and C14H9F3INO, (III), the two benzene rings are inclined to one another by 43.94 (8)° in mol-ecule A and 55.66 (7)° in mol-ecule B of compound (I), which crystallizes with two independent mol-ecules in the asymmetric unit, but by only 10.40 (12)° in compound (II) and 12.5 (2)° in compound (III). In the crystals of all three compounds, N-H⋯O hydrogen bonds link the mol-ecules to form chains propagating along the a-axis direction for (I), and along the b-axis direction for (II) and (III). In the crystal of (I), -A-B-A-B- chains are linked by C-H⋯O hydrogen bonds, forming layers parallel to (010). Within the layers there are weak offset π-π inter-actions present [inter-centroid distances = 3.868 (1) and 3.855 (1) Å]. In the crystals of (II) and (III), the chains are linked via short halogen-halogen contacts [Br⋯Br = 3.6141 (4) Å in (II) and I⋯I = 3.7797 (5) Å in (III)], resulting in the formation of ribbons propagating along the b-axis direction.

  10. Crystal structure of 1-benzyl-3-methyl-1H-imidazolium hexa-fluorido-phosphate.

    Science.gov (United States)

    Hillesheim, Patrick C; Scipione, Kent A

    2014-12-01

    In the title salt, C11H13N2 (+)·PF6 (-), the dihedral angle between the planes of the imidazole and benzene rings is 84.72 (4)°. In the crystal, C-H⋯F inter-actions connect the cation and anion pairs into a three-dimensional network. Weak π-π inter-actions are observed between the imidazolium ring and the aromatic benzene ring of an adjacent mol-ecule with C⋯C and C⋯N distances ranging from 3.3714 (16) to 3.4389 (15) Å.

  11. Crystal structure of 5-[(4-carb-oxy-benz-yl)-oxy]isophthalic acid.

    Science.gov (United States)

    Faizi, Md Serajul Haque; Ahmad, Musheer; Ali, Akram; Potaskalov, Vadim A

    2016-08-01

    The mol-ecular shape of the title compound, C16H12O7, is bent around the central CH2-O bond. The two benzene rings are almost perpendicular to one another, making a dihedral angle of 87.78 (7)°. In the crystal, each mol-ecule is linked to three others by three pairs of O-H⋯O hydrogen bonds, forming undulating sheets parallel to the bc plane and enclosing R 2 (2)(8) ring motifs. The sheets are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming a three-dimensional network.

  12. Crystal structure of bromido-bis-(naph-thal-en-1-yl)anti-mony(III).

    Science.gov (United States)

    Shawkataly, Omar Bin; Hussien Abdelnasir, Hafiz Malik; Rosli, Mohd Mustaqim

    2014-10-01

    In the title compound, [SbBr(C10H7)2], the Sb(III) atom has a distorted trigonal-pyramidal coordination geometry and the planes of the two naphthalene ring systems make a dihedral angle of 80.26 (18)°. An intra-molecular C-H⋯Br hydrogen bond forms an S(5) ring motif. In the crystal, weak C-H⋯Br inter-actions link the mol-ecules into helical chains along the b-axis direction.

  13. Crystal structure of triphenylphosphonium-meth-yl-enetrifluoroborate.

    Science.gov (United States)

    Bateman, Christopher M; Zakharov, Lev N; Abbey, Eric R

    2017-07-01

    The title compound, C19H17BF3P {alternative name: triphen-yl[(tri-fluoro-boran-yl)meth-yl]phosphanium}, was formed by the reaction of tri-phenyl-phosphine with potassium iodo-methyl-tri-fluoro-borate. The mol-ecule features a nearly staggered conformation along the P-C bond and a less than staggered conformation along the C-B bond. In the crystal, weak C-H⋯F hydrogen bonds between the meta-phenyl C-H groups and the tri-fluoro-borate B-F groups form chains of R2(2)(16) rings along [100]. These chains are are further stabilized by weak C-H⋯π inter-actions. A weak intra-molecular C-H⋯F hydrogen bond is also observed.

  14. Crystal structures of (Z)-5-[2-(benzo[b]thio-phen-2-yl)-1-(3,5-di-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole and (Z)-5-[2-(benzo[b]thio-phen-3-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole.

    Science.gov (United States)

    Penthala, Narsimha Reddy; Yadlapalli, Jaishankar K B; Parkin, Sean; Crooks, Peter A

    2016-05-01

    (Z)-5-[2-(Benzo[b]thio-phen-2-yl)-1-(3,5-di-meth-oxy-phen-yl)ethen-yl]-1H-tetrazole methanol monosolvate, C19H16N4O2S·CH3OH, (I), was prepared by the reaction of (Z)-3-(benzo[b]thio-phen-2-yl)-2-(3,5-di-meth-oxy-phen-yl)acrylo-nitrile with tri-butyl-tin azide via a [3 + 2]cyclo-addition azide condensation reaction. The structurally related compound (Z)-5-[2-(benzo[b]thio-phen-3-yl)-1-(3,4,5-tri-meth-oxy-phen-yl)ethen-yl]-1H-tetra-zole, C20H18N4O3S, (II), was prepared by the reaction of (Z)-3-(benzo[b]thio-phen-3-yl)-2-(3,4,5-tri-meth-oxy-phen-yl)acrylo-nitrile with tri-butyl-tin azide. Crystals of (I) have two mol-ecules in the asymmetric unit (Z' = 2), whereas crystals of (II) have Z' = 1. The benzo-thio-phene rings in (I) and (II) are almost planar, with r.m.s deviations from the mean plane of 0.0084 and 0.0037 Å in (I) and 0.0084 Å in (II). The tetra-zole rings of (I) and (II) make dihedral angles with the mean planes of the benzo-thio-phene rings of 88.81 (13) and 88.92 (13)° in (I), and 60.94 (6)° in (II). The di-meth-oxy-phenyl and tri-meth-oxy-phenyl rings make dihedral angles with the benzo-thio-phene rings of 23.91 (8) and 24.99 (8)° in (I) and 84.47 (3)° in (II). In both structures, mol-ecules are linked into hydrogen-bonded chains. In (I), these chains involve both tetra-zole and methanol, and are parallel to the b axis. In (II), mol-ecules are linked into chains parallel to the a axis by N-H⋯N hydrogen bonds between adjacent tetra-zole rings.

  15. Crystal structure and prediction.

    Science.gov (United States)

    Thakur, Tejender S; Dubey, Ritesh; Desiraju, Gautam R

    2015-04-01

    The notion of structure is central to the subject of chemistry. This review traces the development of the idea of crystal structure since the time when a crystal structure could be determined from a three-dimensional diffraction pattern and assesses the feasibility of computationally predicting an unknown crystal structure of a given molecule. Crystal structure prediction is of considerable fundamental and applied importance, and its successful execution is by no means a solved problem. The ease of crystal structure determination today has resulted in the availability of large numbers of crystal structures of higher-energy polymorphs and pseudopolymorphs. These structural libraries lead to the concept of a crystal structure landscape. A crystal structure of a compound may accordingly be taken as a data point in such a landscape.

  16. Crystal structures of 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(3-nitro-phen-yl)acetamide monohydrate and N-(2-chloro-phen-yl)-2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]acetamide.

    Science.gov (United States)

    Subasri, S; Timiri, Ajay Kumar; Barji, Nayan Sinha; Jayaprakash, Venkatesan; Vijayan, Viswanathan; Velmurugan, Devadasan

    2016-08-01

    The title compounds, C12H12N6O3S·H2O, (I), and C12H12ClN5OS, (II), are 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]acetamides. Compound (I) crystallized as a monohydrate. In both compounds, the mol-ecules have a folded conformation, with the pyrimidine ring being inclined to the benzene ring by 56.18 (6)° in (I) and by 67.84 (6)° in (II). In both mol-ecules, there is an intra-molecular N-H⋯N hydrogen bond stabilizing the folded conformation. In (I), there is also a C-H⋯O intra-molecular short contact, and in (II) an intra-molecular N-H⋯Cl hydrogen bond is present. In the crystal of (I), mol-ecules are linked by a series of N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds, forming undulating sheets parallel to the (100). The sheets are linked via an N-H⋯Owater hydrogen bond, forming a three-dimensional network. In the crystal of (II), mol-ecules are linked by a series of N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds, forming slabs parallel to (001).

  17. Comparison of the crystal structures of methyl 4-bromo-2-(meth-oxy-meth-oxy)benzoate and 4-bromo-3-(meth-oxy-meth-oxy)benzoic acid.

    Science.gov (United States)

    Suchetan, P A; Suneetha, V; Naveen, S; Lokanath, N K; Krishna Murthy, P

    2016-04-01

    The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo-hy-droxy-benzoic acids. Compound (II) crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both (I) and (II), the O-CH2-O-CH3 side chain is not in its fully extended conformation; the O-C-O-C torsion angle is 67.3 (3) ° in (I), and -65.8 (3) and -74.1 (3)° in mol-ecules A and B, respectively, in compound (II). In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br⋯O contacts [3.047 (2) Å], forming sheets parallel to the bc plane. The sheets are linked via C-H⋯π inter-actions, forming a three-dimensional architecture. In the crystal of (II), mol-ecules A and B are linked to form R 2 (2)(8) dimers via two strong O-H⋯O hydrogen bonds. These dimers are linked into ⋯A-B⋯A-B⋯A-B⋯ [C 2 (2)(15)] chains along [011] by C-H⋯O hydrogen bonds. The chains are linked by slipped parallel π-π inter-actions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to the bc plane.

  18. Crystal structure of 4,5-bis-(3,4,5-tri-meth-oxy-phen-yl)-2H-1,2,3-triazole methanol monosolvate.

    Science.gov (United States)

    Madadi, Nikhil Reddy; Penthala, Narsimha Reddy; Bommagani, Shobanbabu; Parkin, Sean; Crooks, Peter A

    2014-10-01

    The title compound, C20H23N3O6·CH3OH, was synthesized by [3 + 2] cyclo-addition of (Z)-2,3-bis-(3,4,5-tri-meth-oxy-phen-yl)acrylo-nitrile with sodium azide and ammonium chloride in DMF/water. The central nitro-gen of the triazole ring is protonated. The dihedral angles between the triazole ring and the 3,4,5-tri-meth-oxy-phenyl ring planes are 34.31 (4) and 45.03 (5)°, while that between the 3,4,5-tri-meth-oxy-phenyl rings is 51.87 (5)°. In the crystal, the mol-ecules, along with two methanol solvent mol-ecules are linked into an R (4) 4(10) centrosymmetric dimer by N-H⋯O and O-H⋯N hydrogen bonds.

  19. Crystal structure of N-(tert-but-oxy-carbon-yl)glycyl-(Z)-β-bromo-dehydro-alanine methyl ester [Boc-Gly-(β-Br)((Z))ΔAla-OMe].

    Science.gov (United States)

    Lenartowicz, Paweł; Makowski, Maciej; Zarychta, Bartosz; Ejsmont, Krzysztof

    2014-12-01

    The title compound, C11H17BrN2O5, is a de-hydro-amino acid with a C=C bond between the α- and β-C atoms. The amino acid residues are linked trans to each other and there are no strong intra-molecular hydrogen bonds. The torsion angles indicate a non-helical conformation of the mol-ecule. The dipeptide folding is influenced by an inter-molecular N-H⋯O hydrogen bond and also minimizes steric repulsion. In the crystal, mol-ecules are linked by strong N-H⋯O hydrogen bonds, generating (001) sheets. The sheets are linked by weak C-H⋯O and C-H⋯Br bonds and short Br⋯Br [3.4149 (3) Å] inter-actions.

  20. Crystal structure of 1H,1'H-[2,2'-biimid-azol]-3-ium hydrogen tartrate hemi-hydrate.

    Science.gov (United States)

    Gao, Xiao-Li; Bian, Li-Fang; Guo, Shao-Wei

    2014-11-01

    In the crystal of the title hydrated salt, C6H7N4 (+)·C4H5O6 (-)·0.5H2O, the bi-imidazole monocation, 1H,1'H-[2,2'-biimidazol]-3-ium, is hydrogen bonded, via N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds, to the hydrogen tartrate anion and the water mol-ecule, which is located on a twofold rotation axis, forming sheets parallel to (001). The sheets are linked via C-H⋯O hydrogen bonds, forming a three-dimensional structure. There are also C=O⋯π inter-actions present [O⋯π distances are 3.00 (9) and 3.21 (7) Å], involving the carbonyl O atoms and the imidazolium ring, which may help to consolidate the structure. In the cation, the dihedral angle between the rings is 11.6 (2)°.

  1. Crystal structure of 1-[2-(4-nitro-phen-yl)-4,5-diphenyl-1H-imidazol-1-yl]propan-2-ol.

    Science.gov (United States)

    Simpson, Jim; Mohamed, Shaaban K; Marzouk, Adel A; Abdelhamid, Antar A; Albayati, Mustafa R

    2017-09-01

    The title compound, C24H21N3O3, crystallizes with two unique but closely r.m.s. overlay fit = 0.215 Å) comparable mol-ecules (1 and 2) in the asymmetric unit of the triclinic unit cell. In molecule 1, the dihedral angles between the central imidazlole ring and the benzene-ring substituents are 42.51 (9), 45.41 (9) and 56.92 (8)°, respectively. Comparable data for molecule 2 are 39.36 (10), 34.45 (11) and 60.34 (8)°, respectively. The rings at the 2-positions carry p-nitro substituents that subtend dihedral angles of 12.9 (4)° in mol-ecule 1 and 11.7 (4)° in mol-ecule 2 to their respective benzene ring planes. The imidazole rings also have propan-2-ol substituents on the 1-N atoms, which adopt extended conformations for the N-C-C-C chains. In the crystal, classical O-H⋯N hydrogen bonds combine with C-H⋯O, C-H⋯N and C-H⋯π(ring) hydrogen bonds and stack the molecules along the a-axis direction.

  2. Crystal structure of 1-(8-meth-oxy-2H-chromen-3-yl)ethanone.

    Science.gov (United States)

    Koh, Dongsoo

    2014-09-01

    In the structure of the title compound, C12H12O3, the di-hydro-pyran ring is fused with the benzene ring. The di-hydro-pyran ring is in a half-chair conformation, with the ring O and methyl-ene C atoms positioned 1.367 (3) and 1.504 (4) Å, respectively, on either side of the mean plane formed by the other four atoms. The meth-oxy group is coplanar with the benzene ring to which it is connected [Cb-Cb-Om-Cm torsion angle = -0.2 (4)°; b = benzene and m = meth-oxy], and similarly the aldehyde is coplanar with respect to the double bond of the di-hydro-pyran ring [Cdh-Cdh-Ca-Oa = -178.1 (3)°; dh = di-hydro-pyran and a = aldehyde]. In the crystal, mol-ecules are linked by weak meth-yl-meth-oxy C-H⋯O hydrogen bonds into supra-molecular chains along the a-axis direction.

  3. Crystal structure of tri-hydrogen bis-{[1,1,1-tris-(2-oxido-ethyl-amino-meth-yl)ethane]-cobalt(III)} trinitrate.

    Science.gov (United States)

    Sethi, Waqas; Johannesen, Heini V; Morsing, Thorbjørn J; Piligkos, Stergios; Weihe, Høgni

    2015-12-01

    The title compound, [Co2(L)2](3+)·3NO3 (-) [where L = CH3C(CH2NHCH2CH2OH1/2)3], has been synthesized from the ligand 1,1,1-tris-(2-hy-droxy-ethyl-amino-meth-yl)ethane. The cobalt(III) dimer has an inter-esting and uncommon O-H⋯O hydrogen-bonding motif with the three bridging hy-droxy H atoms each being equally disordered over two positions. In the dimeric trication, the octa-hedrally coordinated Co(III) atoms and the capping C atoms lie on a threefold rotation axis. The N atoms of two crystallographically independent nitrate anions also lie on threefold rotation axes. N-H⋯O hydrogen bonding between the complex cations and nitrate anions leads to the formation of a three-dimensional network structure. The compound is a racemic conglomerate of crystals containing either d or l mol-ecules. The crystal used for this study is a d crystal.

  4. Crystal structure of bis-{(S)-1-[2-(di-phenyl-phosphan-yl)ferrocen-yl]-(R)-eth-yl}ammonium bromide di-chloro-methane monosolvate.

    Science.gov (United States)

    Zirakzadeh, Afrooz; Stöger, Berthold; Kirchner, Karl

    2017-02-01

    During the synthesis of an FeBr2 complex with the PNP ligand (R,R,SFc,SFc)-[Fe2(C5H5)2(C38H35NP2)] (1), single crystals of the di-chloro-methane monosolvate of the Br(-) salt of the protonated ligand 1H(+) were obtained serendipitously, i.e. [Fe2(C5H5)2(C38H36NP2)]Br·CH2Cl2. The crystal structure of 1H·Br·CH2Cl2 was determined by single-crystal X-ray diffraction. The mean bond lengths in the ferrocene units are Fe-C = 2.049 (3) Å and C-C = 1.422 (4) Å within the cyclo-penta-dienyl rings. The mean C-N bond length is 1.523 (4) Å. The inter-planar angle between the two connected cyclo-penta-dienyl rings is 49.2 (2)°. One ferrocene moiety adopts a staggered conformation, whereas the other is between staggered and eclipsed. The Br(-) ions and the CH2Cl2 mol-ecules are located in channels extending along . One ammonium H atom forms a hydrogen bond with the Br(-) ion [H⋯Br = 2.32 (4) Å and C-H⋯Br = 172 (3)°]. The second ammonium H atom is not involved in hydrogen bonding.

  5. Crystal structure of bis-[1,3-bis-(2,6-diiso-propyl-phen-yl)imidazol-2-yl-idene]silver(I) chloride tetrahydro-furan monosolvate.

    Science.gov (United States)

    Sänger, Inge; Lerner, Hans-Wolfram; Bolte, Michael

    2015-05-01

    In the title salt, [Ag(C27H36N2)2]Cl·C4H8O, the Ag(I) atom is coordinated by two 1,3-bis-(2,6-di-methyl-phen-yl)imidazol-2-yl-idene ligands. The imidazole rings are inclined to one another by 46.69 (13)° and the benzene rings in each ligand are almost normal to the imdazole ring to which they are attached, with dihedral angles varying from 82.39 (13) to 88.27 (12)°. There are C-H⋯π inter-actions present in the cation, involving the two ligands, and the solvent mol-ecule is linked to the cation via a C-H⋯O hydrogen bond. In the crystal, mol-ecules are linked by trifurcated C-H⋯(Cl,Cl,Cl) hydrogen bonds, forming slabs parallel to (101). One isopropyl group is disordered over two sets of sites with an occupancy ratio of 0.447 (17):0.553 (17) and the THF mol-ecule is disordered over two positions with an occupancy ratio of 0.589 (6):0.411 (6).

  6. 6-Methyl-2-oxo-N-(quinolin-6-yl)-2H-chromene-3-carboxamide: crystal structure and Hirshfeld surface analysis.

    Science.gov (United States)

    Gomes, Lígia R; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, Fernanda

    2016-08-01

    The title coumarin derivative, C20H14N2O3, displays intra-molecular N-H⋯O and weak C-H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol-ecule [dihedral angle between the coumarin and quinoline ring systems = 6.08 (6)°]. The supra-molecular structures feature C-H⋯O hydrogen bonds and π-π inter-actions, as confirmed by Hirshfeld surface analyses.

  7. Crystal structure of ethyl (E)-4-(4-chlorophen-yl)-4-meth-oxy-2-oxobut-3-enoate.

    Science.gov (United States)

    Flores, Darlene Correia; Vicenti, Juliano Rosa de Menezes; Pereira, Bruna Ávila; da Silva, Gabriele Marques Dias; Zambiazi, Priscilla Jussiane

    2014-09-01

    In the title compound, C13H13ClO4, the dihedral angle between the chloro-benezene ring and the least-squares plane through the 4-meth-oxy-2-oxobut-3-enoate ethyl ester residue (r.m.s. deviation = 0.0975 Å) is 54.10 (5)°. In the crystal, mol-ecules are connected by meth-oxy-ketone and benzene-carboxyl-ate carbonyl C-H⋯O inter-actions, generating a supra-molecular layer in the ac plane.

  8. Crystal structure of di-bromo-meth-oxy-seselin (DBMS), a photobiologically active pyran-ocoumarin.

    Science.gov (United States)

    Bauri, A K; Foro, Sabine; Rahman, A F M M

    2017-05-01

    The title compound, C15H14Br2O4 [systematic name: rac-(9S,10R)-3,9-dibromo-10-methoxy-8,8-dimethyl-9,10-dihydropyrano[2,3-h]chromen-2(8H)-one], is a pyran-ocoumarin derivative formed by the bromination of seselin, which is a naturally occurring angular pyran-ocoumarin isolated from the Indian herb Trachyspermum stictocarpum. In the mol-ecule, the benzo-pyran ring system is essentially planar, with a maximum deviation of 0.044 (2) Å for the O atom. The di-hydro-pyran ring is in a half-chair conformation and the four essentially planar atoms of this ring form a dihedral angle of 4.6 (2)° with the benzo-pyran ring system. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming chains propagating along [010]. In addition, π-π stacking inter-actions, with centroid-centroid distances of 3.902 (2) and 3.908 (2) Å, link the hydrogen-bonded chains into layers parallel to (001).

  9. Crystal structure of ethyl 3-amino-6-methyl-2-[(4-methyl-phen-yl)carbamo-yl]-4-[(E)-2-phenyl-ethen-yl]thieno[2,3-b]pyridine-5-carboxyl-ate monohydrate.

    Science.gov (United States)

    Mague, Joel T; Akkurt, Mehmet; Mohamed, Shaaban K; Bakhite, Etify A; Albayati, Mustafa R

    2016-03-01

    In the title mol-ecule, C27H25N3O3S·H2O, the dihedral angle between the planes of the thienyl ring and the pendant p-tolyl group is 39.25 (6)°, while that between the pyridine ring and the pendant phenyl ring is 44.37 (6)°. In addition, there is a slight twist in the bicyclic core, with a dihedral angle of 2.39 (4)° between the thienyl and pyridine rings. The conformation of the carbamoyl moiety is partially determined by an intra-molecular N-H⋯O hydrogen bond. In the crystal, complementary N-H⋯O hydrogen bonds form dimers which are then associated into chains parallel to the c axis through O-H⋯N hydrogen bonds involving the water mol-ecule of crystallization. Electron density associated with an additional solvent mol-ecule of partial occupancy and disordered about a twofold axis was removed with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s).

  10. Structure of a dinuclear cadmium complex with 2,2'-bi-pyridine, monodentate nitrate and 3-carb-oxy-6-methyl-pyridine-2-carboxyl-ate ligands: intra-molecular carbon-yl(lone pair)⋯π(ring) and nitrate(π)⋯π(ring) inter-actions.

    Science.gov (United States)

    Granifo, Juan; Suarez, Sebastián; Baggio, Ricardo

    2015-08-01

    The centrosymmetric dinuclear complex bis-(μ-3-carb-oxy-6-methyl-pyridine-2-carboxyl-ato)-κ(3) N,O (2):O (2);κ(3) O (2):N,O (2)-bis-[(2,2'-bi-pyridine-κ(2) N,N')(nitrato-κO)cadmium] methanol monosolvate, [Cd2(C8H6NO4)2(NO3)2(C10H8N2)2]·CH3OH, was isolated as colourless crystals from the reaction of Cd(NO3)2·4H2O, 6-methyl-pyridine-2,3-di-carb-oxy-lic acid (mepydcH2) and 2,2'-bi-pyridine in methanol. The asymmetric unit consists of a Cd(II) cation bound to a μ-κ(3) N,O (2):O (2)-mepydcH(-) anion, an N,N'-bidentate 2,2'-bi-pyridine group and an O-mono-dentate nitrate anion, and is completed with a methanol solvent mol-ecule at half-occupancy. The Cd complex unit is linked to its centrosymmetric image through a bridging mepydcH(-) carboxyl-ate O atom to complete the dinuclear complex mol-ecule. Despite a significant variation in the coordination angles, indicating a considerable departure from octa-hedral coordination geometry about the Cd(II) atom, the Cd-O and Cd-N distances in this complex are surprisingly similar. The crystal structure consists of O-H⋯O hydrogen-bonded chains parallel to a, further bound by C-H⋯O contacts along b to form planar two-dimensional arrays parallel to (001). The juxtaposed planes form inter-stitial columnar voids that are filled by the methanol solvent mol-ecules. These in turn inter-act with the complex mol-ecules to further stabilize the structure. A search in the literature showed that complexes with the mepydcH(-) ligand are rare and complexes reported previously with this ligand do not adopt the μ-κ(3) coordination mode found in the title compound.

  11. Crystal structure of 5,5'-bis-(di-methyl-amino)-N,N'-(3-methyl-3-aza-pentane-1,5-di-yl)di(naphthalene-1-sulfonamide).

    Science.gov (United States)

    Horne, Toyketa V; Haque, Syed A; Barton, Adrianne; Hossain, Md Alamgir

    2015-12-01

    In the title compound, C29H37N5O4S2, two arms substituted with dansyl derivatives are connected to a central tertiary amine, where the dihedral angle between the planes of two dansyl units is 56.39 (4)°. Each arm contains a sulfonamide functional group and both N-H groups in the compound are pointed to the same side. The central part of the mol-ecule is disordered over three sets of sites with a refined occupancy ratio of 0.547 (4):0.328 (4):0.125 (3). No intra-molecular π-π or hydrogen-bonding inter-actions are observed. In the crystal, mol-ecules are linked via pairs of N-H⋯O inter-actions involving the same acceptor atom, forming inversion dimers. In addition, C-H⋯O inter-actions exist between molecules, providing further stabilization of dimers.

  12. Crystal structure of 1-(2,4-di-methyl-phen-yl)-2-(4-tri-methyl-silyl-1H-1,2,3-triazol-1-yl)ethanone.

    Science.gov (United States)

    Venkatesh, G B; Nagarajaiah, H; Prasad, N L; HariPrasad, S; Begum, Noor Shahina

    2014-12-01

    The asymmetric unit of the title compound, C15H21N3OSi, contains two mol-ecules with similar conformations (r.m.s. overlay fit for the 20 non-H atoms = 0.163 Å). The dihedral angles between the planes of the 1,2,3-triazole and 2,4-di-methyl-benzene rings are 27.0 (3) and 19.5 (3)°. In the crystal, mol-ecules are linked by very weak C-H⋯O and C-H⋯N hydrogen bonds to generate [100] chains. The chains are cross-linked by C-H⋯π inter-actions.

  13. Crystal structure of 1-[2-(2,6-di-chloro-phen-yl)-4,5-diphenyl-1H-imidazol-1-yl]propan-2-ol.

    Science.gov (United States)

    Akkurt, Mehmet; Jasinski, Jerry P; Mohamed, Shaaban K; Marzouk, Adel A; Albayati, Mustafa R

    2015-05-01

    The central imidazole ring of the title compound, C24H20Cl2N2O, is twisted with respect to with the planes of the 2,6-di-chloro-benzene and two phenyl rings, making dihedral angles of 74.06 (18), 28.52 (17) and 67.65 (18)°, respectively. The phenyl ring not adjacent to the N-bonded 2-hy-droxy-propyl group shows the greatest twist, presumably to minimize steric inter-actions. In the crystal, mol-ecules are linked by O-H⋯N and C-H⋯O hydrogen-bond contacts into chains along the a-axis direction. The series of parallel chains form a two-dimensional sheet approximately parallel to the bc diagonal. In addition, C-H⋯π inter-actions are observed between the sheets. The atoms of the 2-hy-droxy-propyl group and the N atom of the 1H-imidazole ring to which it is bonded are disordered over two sets of sites, with an occupancy ratio of 0.722 (5):0.278 (5). The structure was refined as an inversion twin.

  14. Crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand.

    Science.gov (United States)

    Kessler, Monty; Godemann, Christian; Spannenberg, Anke; Beweries, Torsten

    2016-12-01

    The crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [di-methylbis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κ(2)O,O')titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8, 1, and chlorido-[di-methyl-bis-(η(5)-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κO)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetra-hedral geometry, with the tri-fluoro-methane-sulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively. In 1, weak π-π stacking inter-actions involving the toluene solvent mol-ecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.

  15. Crystal Structures of Furazanes

    OpenAIRE

    Klapötke, Thomas; Schmid, Philipp; Stierstorfer, Jörg

    2015-01-01

    Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und -prüfung) methods. The standard enthalpies of formation were calculated for all...

  16. Crystal structure of bis-(3-bromo-mesit-yl)(quino-lin-1-ium-8-yl)boron(III) tribromide.

    Science.gov (United States)

    Son, Jungho; Tamang, Sem Raj; Hoefelmeyer, James D

    2015-09-01

    The title compound, C27H26.82BBr2.18N(+)·Br3 (-), is a cationic tri-aryl-borane isolated as its tribromide salt. The aryl substituents include a protonated 8-quinolyl group and two 3-bromo-mesityl groups. The mol-ecule was prepared on combination of 3:1 Br2 and dimesit-yl(quinolin-8-yl)borane in hexa-nes. The refinement of the structure indicated a degree of 'over-bromination' (beyond two bromine atoms) for the cation. There are two tribromide ions in the asymmetric unit, both completed by crystallographic inversion symmetry.

  17. Crystal structures of two substituted thia-zolidine derivatives.

    Science.gov (United States)

    Viswanathan, Vijayan; Rao, Naga Siva; Raghunathan, Raghavachary; Velmurugan, Devadasan

    2016-08-01

    In the first of the compounds reported herein, namely 6'-ferrocenyl-6a'-nitro-6',6a',6b',7',9',11a'-hexa-hydro-2H-spiro-[ace-naphthyl-ene-1,11'-chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zol]-2-one, [Fe(C5H5)(C29H21N2O4S)], (I), the thia-zolidine ring adopts a twist conformation on the methine N-C atoms. In the second compound, viz. 6'-(4-methoxy-phen-yl)-6a'-nitro-6',6a',6b',7',9',11a'-hexa-hydro-2H-spiro-[ace-naphthyl-ene-1,11'-chromeno[3',4':3,4]pyrrolo-[1,2-c]thia-zol]-2-one, [Fe(C5H5)(C26H19N2O5S)], (II), the thia-zolidine ring adopts an envelope conformation with a methine C atom as the flap. In both compounds, the pyrrolidine ring adopts a twist conformation on the thia-zolidine and tetra-hydro-pyran C atoms. The mean planes of the thia-zolidine and pyrrolidine rings subtend angles of 67.30 (1) and 62.95 (7)° in (I) and (II), respectively, while the mean plane of the pyrrolidine ring makes dihedral angles of 76.53 (1) and 87.74 (7)° with the ace-naphthyl-ene ring system in (I) and (II), respectively. In both compounds, an intra-molecular C-H⋯O hydrogen bond forms an S(7) ring motif. In the crystal of (I), mol-ecules are linked via two different C-H⋯O hydrogen bonds, forming chains along [001] and [100]. In (II), they are linked through C-H⋯O hydrogen bonds, forming dimers with an R 2 (2)(10) ring motif while C-H⋯π inter-actions link the mol-ecules in a head-to-tail fashion, forming chains along the a-axis direction.

  18. Crystal structure of 1-isopropyl-4,7-dimethyl-3-nitro-naphthalene.

    Science.gov (United States)

    Benharref, Ahmed; Elkarroumi, Jamal; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2015-09-01

    The title compound, C15H17NO2, was synthesized from a mixture of α-himachalene (2-methyl-ene-6,6,9-tri-methylbi-cyclo-[5.4.0(1,7)]undec-8-ene) and β-himachalene (2,6,6,9-tetra-methylbi-cyclo-[5.4.0(1,7)]undeca-1,8-diene), which were isolated from an oil of the Atlas cedar (Cedrus Atlantica). The naphthalene ring system makes dihedral angles of 68.6 (2) and 44.3 (2)°, respectively, with its attached isopropyl C/C/C plane and the nitro group. In the crystal, mol-ecules held together by a C-H⋯O inter-action, forming a chain along [-101].

  19. Hydrogen bonding in the crystal structure of the molecular salt of pyrazole-pyrazolium picrate.

    Science.gov (United States)

    Su, Ping; Song, Xue-Gang; Sun, Ren-Qiang; Xu, Xing-Man

    2016-06-01

    The asymmetric unit of the title organic salt [systematic name: 1H-pyrazol-2-ium 2,4,6-tri-nitro-phenolate-1H-pyrazole (1/1)], H(C3H4N2)2 (+)·C6H2N3O7 (-), consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N-H⋯N hydrogen bond is disordered over both symmetry-unique pyrazole mol-ecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N-H⋯(O,O) hydrogen bonds. In addition, weak C-H⋯O hydrogen bonds link inversion-related chains, forming columns along [100].

  20. Crystal Structures of Furazanes

    Directory of Open Access Journals (Sweden)

    Thomas M. Klapötke

    2015-09-01

    Full Text Available Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA and BAM (Bundesanstalt für Materialforschung und -prüfung methods. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, and the energetic performance was predicted with the EXPLO5 V6.02 computer code.

  1. Disorder of the dimeric TCNQ-TCNQ unit in the crystal structure of [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane).

    Science.gov (United States)

    Černák, Juraj; Kuchár, Juraj; Hegedüs, Michal

    2017-01-01

    Crystallization from an aqueous methanol system composed of Ni(NO3)2, 2,2'-bipyridine (bpy) and LiTCNQ (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane) in a 1:3:2 molar ratio yielded single crystals of bis-[tris-(2,2'-bi-pyridine-κ(2)N,N')nickel(II)] bis-(7,7,8,8-tetra-cyano-quinodi-methane radical anion) bi[7,7,8,8-tetra-cyano-quino-dimethanide] hexa-hydrate, [Ni(C10H8N2)3]2(C24H8N8)(C12H4N4)2·6H2O or [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O. The crystal structure comprises [Ni(bpy)3](2+) complex cations, two centrosymmetric crystallographically independent TCNQ (·-) anion radicals with π-stacked exo groups, and an additional dimeric TCNQ-TCNQ unit which comprises 75.3 (9)% of a σ-dimerized (TCNQ-TCNQ)(2-) dianion and 24.7 (9)% of two TCNQ(·-) anion radicals with tightly π-stacked exo groups. The title complex represents the first example of an Ni(II) complex containing a σ-dimerized (TCNQ-TCNQ)(2-) dianion. Disordered solvent water mol-ecules present in the crystal structure participate in hydrogen-bonding inter-actions.

  2. Crystal structure of [NaZn(BTC)(H2O)4]·1.5H2O (BTC = benzene-1,3,5-tri-carb-oxy-l-ate): a heterometallic coordination compound.

    Science.gov (United States)

    Ni, Min; Li, Quanle; Chen, Hao; Li, Shengqing

    2015-07-01

    The title coordination polymer, poly[[μ-aqua-tri-aqua-(μ3-benzene-1,3,5-tri-carboxyl-ato)sodiumzinc] sesquihydrate], {[NaZn(C9H3O6)(H2O)4]·1.5H2O} n , was obtained in ionic liquid microemulsion at room temperture by the reaction of benzene-1,3,5-tri-carb-oxy-lic acid (H3BTC) with Zn(NO3)2·6H2O in the presence of NaOH. The asymmetric unit comprises two Na(+) ions (each located on an inversion centre), one Zn(2+) ion, one BTC ligand, four coordinating water mol-ecules and two solvent water molecules, one of which is disordered about an inversion centre and shows half-occupation. The Zn(2+) cation is five-coordinated by two carboxyl-ate O atoms from two different BTC ligands and three coordinating H2O mol-ecules; the Zn-O bond lengths are in the range 1.975 (2)-2.058 (3) Å. The Na(+) cations are six-coordinated but have different arrangements of the ligands: one is bound to two carboxyl-ate O atoms of two BTC ligands and four O atoms from four coordinating H2O mol-ecules while the other is bound by four carboxyl-ate O atoms from four BTC linkers and two O atoms of coordinating H2O mol-ecules. The completely deprotonated BTC ligand acts as a bridging ligand binding the Zn(2+) atom and Na(+) ions, forming a layered structure extending parallel to (100). An intricate network of O-H⋯O hydrogen bonds is present within and between the layers.

  3. Crystal structure of 11-(2,3-di-meth-oxy-phen-yl)-14-methyl-12-oxa-8,14-di-aza-tetra-cyclo-[8.3.3.0(1,10).0(2,7)]hexa-deca-2(7),3,5-triene-9,13-dione.

    Science.gov (United States)

    Savithri, M P; Suresh, M; Raghunathan, R; Raja, R; SubbiahPandi, A

    2015-05-01

    The title compound, C22H22N2O5, contains two conformationally similar mol-ecules (A and B) in its the asymmetric unit (r.m.s. overlay fit for the 29 non-H atoms = 0.194 Å). In each mol-ecule, the lactone ring has an envelope conformation with the spiro C atom as the flap. In the crystal, A+A and B+B inversion dimers linked by pairs of N-H⋯O hydrgen bonds occur; in both cases, R 2 (2)(8) loops are generated. A weak C-H⋯O inter-action is also observed, which links the dimers into [010] chains.

  4. Crystal structure of catena-poly[bis(formato-κO)bis-[μ2-1,1'-(1,4-phenyl-ene)bis-(1H-imidazole)-κ(2) N (3):N (3')]cobalt(II)].

    Science.gov (United States)

    Xu, Guo-Wang; Wang, Ye-Nan; Xia, Hong-Xu; Wang, Zhong-Long

    2015-09-01

    A red block-shaped crystal of the title compound, [Co(HCOO)2(C12H10N4)2] n , was obtained by the reaction of cobalt(II) nitrate hexa-hydrate, formic acid and 1,1'-(1,4-phenyl-ene)bis-(1H-imidazole) (bib) mol-ecules. The asymmetric unit consists of one Co(II) cation, one formate ligand and two halves of a bib ligand. The central Co(II) cation, located on an inversion centre, is coordinated by two carboxyl-ate O atoms and four N atoms from bib ligands, completing an octa-hedral coordination geometry. The Co(II) centres are bridged by bib ligands, giving a two-dimensional net. Topologically, taking the Co(II) atoms as nodes and the bib ligands as linkers, the two-dimensional structure can be simplified as a typical sql/Shubnikov tetra-gonal plane network. The structure features C-H⋯O hydrogen-bonding inter-actions between formate and bib ligands, resulting in a three-dimensional supra-molecular network.

  5. Crystal structures of bis-(phen-oxy)silicon phthalocyanines: increasing π-π inter-actions, solubility and disorder and no halogen bonding observed.

    Science.gov (United States)

    Lessard, Benoît H; Lough, Alan J; Bender, Timothy P

    2016-07-01

    We report the syntheses and characterization of three solution-processable phen-oxy silicon phthalocyanines (SiPcs), namely bis-(3-methyl-phen-oxy)(phthalocyanine)silicon [(3MP)2-SiPc], C46H30N8O2Si, bis-(2-sec-butyl-phen-oxy)(phthalocyanine)silicon [(2secBP)2-SiPc], C44H24I2N8O2Si, and bis-(3-iodo-phen-oxy)(phthalocyanine)silicon [(3IP)2-SiPc], C52H42N8O2Si. Crystals grown of these compounds were characterized by single-crystal X-ray diffraction and the π-π inter-actions between the aromatic SiPc cores were studied. It was determined that (3MP)2-SiPc has similar inter-actions to previously reported bis-(3,4,5-tri-fluoro-phen-oxy)silicon phthalocyanines [(345 F)2-SiPc] with significant π-π inter-actions between the SiPc groups. (3IP)2-SiPc and (2secBP)2-SiPc both experienced a parallel stacking of two of the peripheral aromatic groups. In all three cases, the solubility of these mol-ecules was increased by the addition of phen-oxy groups while maintaining π-π inter-actions between the aromatic SiPc groups. The solubility of (2secBP)2-SiPc was significantly higher than other bis-phen-oxy-SiPcs and this was exemplified by the higher observed disorder within the crystal structure.

  6. Distinguishing tautomerism in the crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide using DFT-D calculations and {sup 13}C solid-state NMR

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaozhou; Bond, Andrew D.; Johansson, Kristoffer E.; Van de Streek, Jacco, E-mail: jacco.vandestreek@sund.ku.dk [Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen DK-2100 (Denmark)

    2014-08-01

    The crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide contains an imine tautomer, rather than the previously reported amine tautomer. The tautomers can be distinguished using dispersion-corrected density functional theory calculations and by comparison of calculated and measured {sup 13}C solid-state NMR spectra. The crystal structure of the title compound, C{sub 11}H{sub 13}N{sub 3}O{sub 2}S{sub 2}, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated {sup 13}C solid-state NMR spectra [Hangan et al. (2010 ▶). Acta Cryst. B66, 615–621]. The mol@@ecule is tautomeric, and was reported as an amine tautomer [systematic name: N-(5-ethyl-1,3,4-thia@@diazol-2-yl)-p-toluene@@sulfonamide], rather than the correct imine tautomer. The protonation site on the mol@@ecule’s 1,3,4-thia@@diazole ring is indicated by the inter@@molecular contacts in the crystal structure: N—H⋯O hydrogen bonds are established at the correct site, while the alternative protonation site does not establish any notable inter molecular inter@@actions. The two tautomers provide essentially identical Rietveld fits to laboratory PXRD data, and therefore they cannot be directly distinguished in this way. However, the correct tautomer can be distinguished from the incorrect one by previously reported qu@@anti@@tative criteria based on the extent of structural distortion on optimization of the crystal structure using dispersion-corrected density functional theory (DFT-D) calculations. Calculation of the {sup 13}C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured {sup 13}C SS-NMR spectrum.

  7. Crystal structure of cyclo-bis-(μ4-2,2-di-allyl-malonato-κ(6) O (1),O (3):O (3):O (1'),O (3'):O (1'))tetra-kis-(triphenyl-phosphane-κP)tetra-silver(I).

    Science.gov (United States)

    Frenzel, Peter; Jakob, Alexander; Schaarschmidt, Dieter; Rüffer, Tobias; Lang, Heinrich

    2014-10-01

    In the tetra-nuclear mol-ecule of the title compound, [Ag4(C9H10O4)2(C18H15P)4], the Ag(I) ion is coordinated by one P and three O atoms in a considerably distorted tetra-hedral environment. The two 2,2-di-allyl-malonate anions bridge four Ag(I) ions in a μ4-(κ(6) O (1),O (3):O (3):O (1'),O (3'):O (1')) mode, setting up an Ag4O8P4 core (point group symmetry -4..) of corner-sharing tetra-hedra. The shortest intra-molecular Ag⋯Ag distance of 3.9510 (3) Å reveals that no direct d (10)⋯d (10) inter-actions are present. Four weak intra-molecular C-H⋯O hydrogen bonds are observed in the crystal structure of the title compound, which most likely stabilize the tetra-nuclear silver core.

  8. Crystal structure of 3-{[4-(2-meth-oxy-phen-yl)piperazin-1-yl]meth-yl}-5-(thio-phen-2-yl)-1,3,4-oxa-diazole-2(3H)-thione.

    Science.gov (United States)

    Al-Alshaikh, Monirah A; Abuelizz, Hatem A; El-Emam, Ali A; Abdelbaky, Mohammed S M; Garcia-Granda, Santiago

    2016-02-01

    The title compound, C18H20N4O2S2, is a new 1,3,4-oxa-diazole and a key pharmacophore of several biologically active agents. It is composed of a meth-yl(thio-phen-2-yl)-1,3,4-oxa-diazole-2(3H)-thione moiety linked to a 2-meth-oxy-phenyl unit via a piperazine ring that has a chair conformation. The thio-phene ring mean plane lies almost in the plane of the oxa-diazole ring, with a dihedral angle of 4.35 (9)°. The 2-meth-oxy-phenyl ring is almost normal to the oxa-diazole ring, with a dihedral angle of 84.17 (10)°. In the crystal, mol-ecules are linked by weak C-H⋯S hydrogen bonds and C-H⋯π inter-actions, forming layers parallel to the bc plane. The layers are linked via weak C-H⋯O hydrogen bonds and slipped parallel π-π inter-actions [inter-centroid distance = 3.6729 (10) Å], forming a three-dimensional structure. The thio-phene ring has an approximate 180° rotational disorder about the bridging C-C bond.

  9. Crystal structure of bis-[μ-(4-meth-oxy-phen-yl)methane-thiol-ato-κ(2) S:S]bis-[chlorido-(η(6)-1-isopropyl-4-methyl-benzene)-ruthenium(II)] chloro-form disolvate.

    Science.gov (United States)

    Stíbal, David; Süss-Fink, Georg; Therrien, Bruno

    2015-10-01

    The mol-ecular structure of the title complex, [Ru2(C8H9OS)2Cl2(C10H14)2]·2CHCl3 or (p-MeC6H4Pr (i) )2Ru2(SCH2-p-C6H5-OCH3)2Cl2·2CHCl3, shows inversion symmetry. The two symmetry-related Ru(II) atoms are bridged by two 4-meth-oxy-α-toluene-thiol-ato [(4-meth-oxy-phen-yl)methane-thiol-ato] units. One chlorido ligand and the p-cymene ligand complete the typical piano-stool coordination environment of the Ru(II) atom. In the crystal, the CH moiety of the chloro-form mol-ecule inter-acts with the chlorido ligand of the dinuclear complex, while one Cl atom of the solvent inter-acts more weakly with the methyl group of the bridging 4-meth-oxy-α-toluene-thiol-ato unit. This assembly leads to the formation of supra-molecular chains extending parallel to [021].

  10. Crystal structure of bis-[2-tert-but-oxy-6-fluoro-3-(pyridin-2-yl-κN)pyridin-4-yl-κC (4)](pentane-2,4-dionato-κ(2) O,O')iridium(III).

    Science.gov (United States)

    Park, Ki-Min; Kang, Youngjin

    2014-11-01

    The title mol-ecule, [Ir(C14H14FN2O)2(C5H7O2)], is located on a twofold rotation axis, which passes through the Ir(III) atom and the central C atom of the pentane-2,4-dionate anion. The Ir(III) atom adopts a distorted octa-hedral coordination geometry, being C,N-chelated by two 2-tert-but-oxy-6-fluoro-3-(pyridin-2-yl)pyridin-4-yl ligands and O,O'-chelated by the pentane-2,4-dionato ligand. The bipyridinate ligands, which are perpendicular to each other [dihedral angle between the two least-squares planes = 89.95 (5)°], are arranged in a cis-C,C' and trans-N,N' fashion relative to the central metal cation. Intra-molecular C-H⋯O and C-H⋯N hydrogen bonds and inter-molecular C-H⋯F hydrogen bonds as well as π-π inter-actions between neighbouring pyridine rings [centroid-centroid distance 3.680 (1) Å] contribute to the stabilization of the mol-ecular and crystal structure, respectively.

  11. Synthesis and crystal structure of trans-di-chlorido[3-methyl-1-(4-vinyl-benz-yl)-1H-imidazol-3-ium-2-yl-κC (2)](4-phenyl-pyridine-κN)palladium(II).

    Science.gov (United States)

    Majeed, Maitham H; Wendt, Ola F

    2016-04-01

    The title compound, [PdCl2(C11H9N)(C13H14N2)], represents a new class of palladium-based polymerizable monomer which could give a potentially catalytically active polymer. It was synthesized via transmetallation from the corresponding silver complex. The Pd(II) ion coordinates two Cl anions, one C atom from the N-heterocyclic carbene (NHC) ligand and one N atom from the 4-phenyl-pyridine ligand, displaying a slightly distorted square-planar geometry. The dihedral angle between the imidazole ring and the pyridine ring is 34.53 (8)°. The Pd-C bond length between the NHC ligand and the Pd(II) ion is 1.9532 (16) Å. In the crystal, weak non-classical C-H⋯Cl hydrogen bonds link the mol-ecules into a tape structure along [101]. A weak π-π inter-action is also observed [centroid-centroid distance = 3.9117 (11) Å].

  12. Two tautomers in the same crystal: 3-(4-fluoro-phen-yl)-1H-pyrazole and 5-(4-fluoro-phen-yl)-1H-pyrazole.

    Science.gov (United States)

    Yamuna, Thammarse S; Kaur, Manpreet; Jasinski, Jerry P; Anderson, Brian J; Yathirajan, H S

    2014-09-01

    The title co-crystal, 3-(4-fluoro-phen-yl)-1H-pyrazole-5-(4-fluoro-phen-yl)-1H-pyrazole (1/1), C9H7FN2, crystallizes with four independent mol-ecules (A, B, C and D) in the asymmetric unit exhibiting two tautomeric forms (A and D; B and C) due to N-H proton exchange between the two N atoms of the pyrazole ring. The dihedral angles between the mean planes of the pyrazole and benzene rings are 15.6 (1), 19.8 (9), 14.0 (1) and 10.7 (7)° in mol-ecules A, B, C and D, respectively. In the crystal, N-H⋯N hydrogen bonds link the four mol-ecules in the asymmetric unit into a ring with an R 4 (4)(12) motif. Furthermore, weak C-H⋯F inter-actions link the mol-ecules into a three-dimensional network.

  13. Frustrated polymer crystal structures

    Science.gov (United States)

    Lotz, B.; Strasbourg, 67083

    1997-03-01

    Several crystal structures or polymorphs of chiral or achiral polymers and biopolymers with three fold conformation of the helix have been found to conform to a common and -with one exception(Puterman, M. et al, J. Pol. Sci., Pol. Phys. Ed., 15, 805 (1977))- hitherto unsuspected packing scheme. The trigonal unit-cell contains three isochiral helices; the azimuthal setting of one helix differs significantly from that of the other two, leading to a so-called frustrated packing scheme, in which the environment of conformationally identical helices differs. Two variants of the frustrated scheme are analyzed. Similarities with frustrated two dimensional magnetic systems are underlined. Various examples of frustration in polymer crystallography are illustrated via the elucidation or reinterpretation of crystal phases or polymorphs of polyolefins, polyesters, cellulose derivatives and polypeptides. Structural manifestations (including AFM evidence) and morphological consequences of frustration are presented, which help diagnose the existence of this original packing of polymers.(Work done with L. Cartier, D. Dorset, S. Kopp, T. Okihara, M. Schumacher, W. Stocker.)

  14. Inorganic Crystal Structure Database (ICSD)

    Science.gov (United States)

    SRD 84 FIZ/NIST Inorganic Crystal Structure Database (ICSD) (PC database for purchase)   The Inorganic Crystal Structure Database (ICSD) is produced cooperatively by the Fachinformationszentrum Karlsruhe(FIZ) and the National Institute of Standards and Technology (NIST). The ICSD is a comprehensive collection of crystal structure data of inorganic compounds containing more than 140,000 entries and covering the literature from 1915 to the present.

  15. Crystal structure of ruthenocenecarbonitrile

    Directory of Open Access Journals (Sweden)

    Frank Strehler

    2015-04-01

    Full Text Available The molecular structure of ruthenocenecarbonitrile, [Ru(η5-C5H4C[triple-bond]N(η5-C5H5], exhibits point group symmetry m, with the mirror plane bisecting the molecule through the C[triple-bond]N substituent. The RuII atom is slightly shifted from the η5-C5H4 centroid towards the C[triple-bond]N substituent. In the crystal, molecules are arranged in columns parallel to [100]. One-dimensional intermolecular π–π interactions [3.363 (3 Å] between the C[triple-bond]N carbon atom and one carbon of the cyclopentadienyl ring of the overlaying molecule are present.

  16. Crystal structure of propaquizafop

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2014-12-01

    Full Text Available The title compound, C22H22ClN3O5 {systematic name: 2-(propan-2-ylideneaminooxyethyl (R-2-[4-(6-chloroquinoxalin-2-yloxyphenoxy]propionate}, is a herbicide. The asymmetric unit comprises two independent molecules in which the dihedral angles between the phenyl ring and the quinoxaline ring plane are 75.93 (7 and 82.77 (8°. The crystal structure features C—H...O, C—H...N, and C—H...Cl hydrogen bonds, as well as weak π–π interactions [ring-centroid separation = 3.782 (2 and 3.5952 (19 Å], resulting in a three-dimensional architecture.

  17. Photonic Crystal Laser Accelerator Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, Benjamin M

    2003-05-21

    Photonic crystals have great potential for use as laser-driven accelerator structures. A photonic crystal is a dielectric structure arranged in a periodic geometry. Like a crystalline solid with its electronic band structure, the modes of a photonic crystal lie in a set of allowed photonic bands. Similarly, it is possible for a photonic crystal to exhibit one or more photonic band gaps, with frequencies in the gap unable to propagate in the crystal. Thus photonic crystals can confine an optical mode in an all-dielectric structure, eliminating the need for metals and their characteristic losses at optical frequencies. We discuss several geometries of photonic crystal accelerator structures. Photonic crystal fibers (PCFs) are optical fibers which can confine a speed-of-light optical mode in vacuum. Planar structures, both two- and three-dimensional, can also confine such a mode, and have the additional advantage that they can be manufactured using common microfabrication techniques such as those used for integrated circuits. This allows for a variety of possible materials, so that dielectrics with desirable optical and radiation-hardness properties can be chosen. We discuss examples of simulated photonic crystal structures to demonstrate the scaling laws and trade-offs involved, and touch on potential fabrication processes.

  18. Crystal structure of 5-[4-(di-methyl-amino)-phen-yl]-3-(4-methyl-phen-yl)-4,5-di-hydro-1H-pyrazole-1-carbaldehyde.

    Science.gov (United States)

    Adam, Farook; Samshuddin, Seranthimata; Ameram, Nadiah; Subramaya; Samartha, Laxminarayana

    2015-12-01

    The title compound, C19H21N3O, comprises a central pyrazole ring which is N-connected to an aldehyde group and C-connected twice to substituted benzene rings. The pyrazole ring is twisted on the C-C single bond, and the least-squares plane through this ring forms dihedral angles of 82.44 (5) and 4.52 (5)° with the (di-methyl-amino)-benzene and p-tolyl rings, respectively. In the crystal, weak C-H⋯O hydrogen bonds link mol-ecules into supra-molecular tubes along the b axis.

  19. Crystal structure of fipronil

    Directory of Open Access Journals (Sweden)

    Hyunjin Park

    2017-10-01

    Full Text Available The title compound, C12H4Cl2F6N4OS {systematic name: 5-amino-1-[2,6-dichloro-4-(trifluoromethylphenyl]-4-[(trifluoromethanesulfinyl]-1H-pyrazole-3-carbonitrile}, is a member of the phenylpyrazole group of acaricides, and one of the phenylpyrazole group of insecticides. The dihedral angle between the planes of the pyrazole and benzene rings is 89.03 (9°. The fluorine atoms of the trifluoromethyl substituent on the benzene ring are disordered over two sets of sites, with occupancy ratios 0.620 (15:0.380 (15. In the crystal, C—N...π interactions [N...ring centroid = 3.607 (4 Å] together with N—H...N and C—H...F hydrogen bonds form a looped chain structure along [10\\overline{1}]. Finally, N—H...O hydrogen bonds and C—Cl...π interactions [Cl...ring centroid = 3.5159 (16 Å] generate a three-dimensional structure. Additionally, there are a short intermolecular F... F contacts present.

  20. Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium chloride 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate: a new polymorph of l-dopa HCl and isotypic with its bromide counterpart.

    Science.gov (United States)

    Kathiravan, Perumal; Balakrishnan, Thangavelu; Venkatesan, Perumal; Ramamurthi, Kandasamy; Percino, María Judith; Thamotharan, Subbiah

    2016-11-01

    The title mol-ecular salt, C9H12NO4(+)·Cl(-)·C9H11NO4, is isotypic with that of the bromide counterpart [Kathiravan et al. (2016 ▸). Acta Cryst. E72, 1544-1548]. The title salt is a second monoclinic polymorph of the l-dopa HCl structure reported earlier in the monoclinic space group P21 [Jandacek & Earle (1971 ▸). Acta Cryst. B27, 841-845; Mostad & Rømming (1974 ▸). Acta Chemica Scand. B28, 1161-1168]. In the title compound, monoclinic space group I2, one of the dopa mol-ecules has a positive charge with a protonated α-amino group and the α-carb-oxy-lic acid group uncharged, while the second dopa mol-ecule has a neutral charge, the α-amino group is protonated and the α-carb-oxy-lic acid is deprotonated. In the previously reported form, a single dopa mol-ecule is observed in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged. The invariant and variations of various types of inter-molecular inter-actions present in these two forms of dopa HCl structures are discussed with the aid of two-dimensional fingerprint plots.

  1. Crystal structure of 2,2-di-chloro-1-(piperidin-1-yl)butane-1,3-dione.

    Science.gov (United States)

    Schwierz, Markus; Görls, Helmar; Imhof, Wolfgang

    2015-01-01

    In the title compound, C9H13Cl2NO2, the piperidine ring shows a chair conformation and the O-C-C-O torsion angle between the carbonyl groups is 183.6 (4)°. In the crystal, mol-ecules are linked into an infinite layer along the ab plane by a bifurcated C-H⋯O hydrogen bond between the carbonyl O atom adjacent to the methyl group and one of the methyl-ene groups next to nitro-gen and an additional hydrogen bond of the C-H⋯Cl type. These layers are connected into a three-dimensional supra-molecular arrangement by O⋯Cl contacts [2.8979 (12) and 3.1300 (12) Å].

  2. Prediction of molecular crystal structures

    CERN Document Server

    Beyer, T

    2001-01-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of parac...

  3. THE CRYSTAL STRUCTURE OF DIPHENYLTELLURIUM DIBROMIDE,

    Science.gov (United States)

    TELLURIUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, CRYSTAL STRUCTURE , CRYSTAL STRUCTURE , BROMIDES, SYMMETRY(CRYSTALLOGRAPHY), X RAY DIFFRACTION, FOURIER ANALYSIS, LEAST SQUARES METHOD, MOLECULAR STRUCTURE, CHEMICAL BONDS.

  4. REFINEMENT OF THE CRYSTAL STRUCTURE OF GUANIDINIUM ALUMINUM SULFATE HEXAHYDRATE.

    Science.gov (United States)

    FERROELECTRIC CRYSTALS, * CRYSTAL STRUCTURE ), (*GUANIDINES, CRYSTAL STRUCTURE ), (*ALUMINUM COMPOUNDS, CRYSTAL STRUCTURE ), SULFATES, HYDRATES, X RAY DIFFRACTION, CHROMIUM COMPOUNDS, CRYSTAL LATTICES, CHEMICAL BONDS

  5. Demonstration of Crystal Structure.

    Science.gov (United States)

    Neville, Joseph P.

    1985-01-01

    Describes an experiment where equal parts of copper and aluminum are heated then cooled to show extremely large crystals. Suggestions are given for changing the orientation of crystals by varying cooling rates. Students are more receptive to concepts of microstructure after seeing this experiment. (DH)

  6. Crystal structure of oxamyl

    Directory of Open Access Journals (Sweden)

    Eunjin Kwon

    2016-12-01

    Full Text Available The title compound, C7H13N3O3S [systematic name: (Z-methyl 2-dimethylamino-N-(methylcarbamoyloxy-2-oxoethanimidothioate], is an oxime carbamate acaride, insecticide and nematicide. The asymmetric unit comprises two independent molecules, A and B. The dihedral angles between the mean planes [r.m.s. deviations = 0.0017 (A and 0.0016 Å (B] of the acetamide and oxyimino groups are 88.80 (8° for A and 87.05 (8° for B. In the crystal, N/C—H...O hydrogen bonds link adjacent molecules, forming chains along the a axis. The chains are further linked by C—H...O hydrogen bonds, resulting in a three-dimensional network with alternating rows of A and B molecules in the bc plane stacked along the a-axis direction. The structure was refined as an inversion twin with a final BASF parameter of 0.16 (9.

  7. Prediction of molecular crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Theresa

    2001-07-01

    The ab initio prediction of molecular crystal structures is a scientific challenge. Reliability of first-principle prediction calculations would show a fundamental understanding of crystallisation. Crystal structure prediction is also of considerable practical importance as different crystalline arrangements of the same molecule in the solid state (polymorphs)are likely to have different physical properties. A method of crystal structure prediction based on lattice energy minimisation has been developed in this work. The choice of the intermolecular potential and of the molecular model is crucial for the results of such studies and both of these criteria have been investigated. An empirical atom-atom repulsion-dispersion potential for carboxylic acids has been derived and applied in a crystal structure prediction study of formic, benzoic and the polymorphic system of tetrolic acid. As many experimental crystal structure determinations at different temperatures are available for the polymorphic system of paracetamol (acetaminophen), the influence of the variations of the molecular model on the crystal structure lattice energy minima, has also been studied. The general problem of prediction methods based on the assumption that the experimental thermodynamically stable polymorph corresponds to the global lattice energy minimum, is that more hypothetical low lattice energy structures are found within a few kJ mol{sup -1} of the global minimum than are likely to be experimentally observed polymorphs. This is illustrated by the results for molecule I, 3-oxabicyclo(3.2.0)hepta-1,4-diene, studied for the first international blindtest for small organic crystal structures organised by the Cambridge Crystallographic Data Centre (CCDC) in May 1999. To reduce the number of predicted polymorphs, additional factors to thermodynamic criteria have to be considered. Therefore the elastic constants and vapour growth morphologies have been calculated for the lowest lattice energy

  8. Crystal structure of 2-{(R)-[1-(4-bromo-phen-yl)eth-yl]imino-meth-yl}-4-(phenyl-diazen-yl)phenol, a chiral photochromic Schiff base.

    Science.gov (United States)

    Moriwaki, Ryoji; Akitsu, Takashiro

    2015-11-01

    The title chiral photochromic Schiff base compound, C21H18BrN3O, was synthesized from (R)-(+)-1-(4-bromo-phen-yl)ethyl-amine and the salicyl-aldehyde of an azo-benzene derivative. The mol-ecule corresponds to the phenol-imine tautomer, the C=N and N-C bond distances being 1.285 (3) and 1.470 (3) Å, respectively. The diazenyl group adopts a trans form, with an N=N distance of 1.256 (3) Å. The hy-droxy group is involved in intra-molecular O-H⋯N hydrogen bonding. In the crystal, C-H⋯π inter-actions consolidate the crystal packing of one-dimensional chains, which exhibits short inter-molecular Br⋯C contacts of 3.400 (3) Å.

  9. Crystal structure of an organic-inorganic hybrid compound based on morpholinium cations and a β-type Anderson polyanion.

    Science.gov (United States)

    Lukianova, Tamara J; Kinzhybalo, Vasyl; Pietraszko, Adam

    2015-11-01

    A new organic-inorganic hybrid compound, penta-morpholinium hexa-hydrogen hexa-molybdoferrate(III) sulfate 3.5-hydrate, (C4H10NO)5[Fe(III)(OH)6Mo6O18](SO4)·3.5H2O, was obtained from an aqueous solution. The polyoxidomolybdate (POM) anion is of the Anderson β-type with a central Fe(III) ion. Three of five crystallographically independent morpholinium cations are disordered over two sets of sites. An intricate network of inter-molecular N-H⋯O and O-H⋯O inter-actions between cations, POMs, sulfate anions and non-coordinating water mol-ecules creates a three-dimensional network structure.

  10. Crystal structure of a binuclear nickel(II) complex constructed of 1H-imidazo[4,5-f][1,10]phenanthroline and doubly deprotonated benzene-1,3,5-tri-carb-oxy-lic acid.

    Science.gov (United States)

    Lv, Ying; Hao, Xiang-Rong

    2015-04-01

    The title complex, [Ni2(C9H4O6)2(C13H8N4)2(H2O)4]·2H2O, bis-(μ-5-carb-oxy-benzene-1,3-di-carboxyl-ato-κ(2) O (1):O (1'))bis-[di-aqua(1H-imidazo[4,5-f][1,10]phenanthroline-κ(2) N (7),N (8))nickel(II)] di-hydrate, was obtained under solvothermal conditions by the reaction of benzene-1,3,5-tricarboxylic acid (H3BTC) with Ni(NO3)2 in the presence of 1H-imidazo[4,5-f][1,10]phenanthroline (IP). The crystal has triclinic (P-1) symmetry with a centrosymmetric binuclear nickel(II) cluster. The Ni(II) atom is coordinated by two N atoms from a chelating 1H-imidazo[4,5-f][1,10]phenanthroline ligand, two carboxyl-ate O atoms from two 5-carb-oxy-benzene-1,3-di-carboxyl-ate ligands and two water mol-ecules in a slightly distorted octa-hedral geometry. Two carboxyl-ate groups bridge two Ni(II) cations, forming the binuclear complex. Extensive N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonding is present in the crystal structure, forming a three-dimensional supermolecular framework. Weak π-π stacking is observed between parallel HBTC(2-) and IP ring systems, the face-to-face separation being 3.695 (2) Å.

  11. Crystal structure of cafenstrole

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound (systematic name: N,N-diethyl-3-mesitylsulfonyl-1H-1,2,4-triazole-1-carboxamide, C16H22N4O3S, is a triazole herbicide. The dihedral angle between the planes of the triazole and benzene ring planes is 88.14 (10°. In the crystal, C—H...O hydrogen bonds and weak C—H...π interactions link adjacent molecules, forming one-dimensional chains along the a axis.

  12. Crystal structure of pseudoguainolide

    Directory of Open Access Journals (Sweden)

    Noureddine Beghidja

    2015-03-01

    Full Text Available The lactone ring in the title molecule, C15H22O3 (systematic name: 3,4a,8-trimethyldodecahydroazuleno[6,5-b]furan-2,5-dione, assumes an envelope conformation with the methine C atom adjacent to the the methine C atom carrying the methyl substituent being the flap atom. The other five-membered ring adopts a twisted conformation with the twist being about the methine–methylene C—C bond. The seven-membered ring is based on a twisted boat conformation. No specific interactions are noted in the the crystal packing.

  13. Structural characterization of two tetra-chlorido-zincate salts of 4-carb-oxy-1H-imidazol-3-ium: a salt hydrate and a co-crystal salt hydrate.

    Science.gov (United States)

    Martens, Sean J; Geiger, David K

    2017-02-01

    Imidazole-containing compounds exhibit a myriad of pharmacological activities. Two tetra-chlorido-zincate salts of 4-carb-oxy-1H-imidazol-3-ium, ImHCO2H(+), are reported. Bis(4-carb-oxy-1H-imidazol-3-ium) tetra-chlorido-zincate monohydrate, (C4H5N2O2)2[ZnCl4]·H2O, (I), crystallizes as a monohydrate salt, while bis-(4-carb-oxy-1H-imidazol-3-ium) tetra-chlorido-zincate bis-(1H-imidazol-3-ium-4-carboxyl-ato) monohydrate, (C4H5N2O2)2[ZnCl4]·2C4H4N2O2·H2O, (II), is a co-crystal salt with six residues: two ImHCO2H(+) cations, two formula units of the zwitterionic 1H-imidazol-3-ium-4-carboxyl-ate, ImHCO2, one tetra-chlorido-zincate anion and one water mol-ecule disordered over two sites in a 0.60 (4):0.40 (4) ratio. The geometric parameters of the ImHCO2H(+) and the ImHCO2 moieties are the same within the standard uncertainties of the measurements. Both compounds exhibit extensive hydrogen bonding, including involvement of the tetra-chlorido-zincate anion, resulting in inter-connected chains of anions joined by water mol-ecules.

  14. Crystal structure of nuarimol

    Directory of Open Access Journals (Sweden)

    Gihaeng Kang

    2015-08-01

    Full Text Available The title compound [systematic name: (RS-(2-chlorophenyl(4-fluorophenyl(pyrimidin-5-ylmethanol], C17H12ClFN2O, is a pyrimidine fungicide. The asymmetric unit comprises two independent molecules, A and B, in which the dihedral angles between the plane of the pyrimidine ring and those of the chlorophenyl and fluorophenyl rings are 71.10 (6 and 70.04 (5° in molecule A, and 73.24 (5 and 89.30 (5° in molecule B. In the crystal, O—H...N hydrogen bonds link the components into [010] chains of alternating A and B molecules. The chains are cross-linked by C—H...F hydrogen bonds and weak C—H...π and C—Cl...π [Cl...ring centroid = 3.7630 (8 Å] interactions, generating a three-dimensional network.

  15. Crystal structure refinement with SHELXL.

    Science.gov (United States)

    Sheldrick, George M

    2015-01-01

    The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

  16. Crystal structure refinement with SHELXL

    Energy Technology Data Exchange (ETDEWEB)

    Sheldrick, George M., E-mail: gsheldr@shelx.uni-ac.gwdg.de [Department of Structural Chemistry, Georg-August Universität Göttingen, Tammannstraße 4, Göttingen 37077 (Germany)

    2015-01-01

    New features added to the refinement program SHELXL since 2008 are described and explained. The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as ‘a CIF’) containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

  17. Crystal structure of pymetrozine

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2015-07-01

    Full Text Available The title compound, C10H11N5O {systematic name: 6-methyl-4-[(E-(pyridin-3-ylmethylideneamino]-4,5-dihydro-1,2,4-triazin-3(2H-one}, C10H11N5O, is used as an antifeedant in pest control. The asymmetric unit comprises two independent molecules, A and B, in which the dihedral angles between the pyridinyl and triazinyl ring planes [r.m.s. deviations = 0.0132 and 0.0255 ] are 11.60 (6 and 18.06 (4°, respectively. In the crystal, N—H...O, N—H...N, C—H...N and C—H...O hydrogen bonds, together with weak π–π interactions [ring-centroid separations = 3.5456 (9 and 3.9142 (9 Å], link the pyridinyl and triazinyl rings of A molecules, generating a three-dimensional network.

  18. Crystal structure of tris-(1,3-dimesityl-4,5-di-hydro-1H-imidazol-3-ium) tetra-bromido-cobaltate(II) bromide chloro-form hexa-solvate.

    Science.gov (United States)

    Rais, Eduard; Flörke, Ulrich; Wilhelm, René

    2015-10-01

    In the unit cell of the title compound, (C21H27N2)3[CoBr4]Br·6CHCl3, the tetrabromidocobaltate(II) anion and the bromide anion are located on a crystallographic threefold rotation axis. For the [CoBr4](2-) group, the axis runs through one of the Br ligands and the Co(II) atom. All other structure moieties lie on general sites. Various tris-(1,3-dimesityl-4,5-di-hydro-1H-imidazol-3-ium) structures with different counter-ions have been reported. In the title compound, the N-C-N angle is 113.7 (5)°, with short C-N bond lengths of 1.297 (7) and 1.307 (7) Å. The two mesityl planes make a dihedral angle of 34.6 (1)° and the dihedral angles between the mesityl and N-C-N planes are 82.0 (1) and 88.5 (1)°, respectively. The imidazoline ring is almost planar, with atom deviations in the range 0.003 (5)-0.017 (5) Å from the best plane; the mean deviation is 0.012 (5) Å. In the crystal, non-covalent inter-actions of the C-H⋯Br type occur between the Br(-) anion and the cation, as well as between the [CoBr4](2-) anion and both the chloro-form solvent mol-ecules. These H⋯A distances are slightly shorter than the sum of van der Waals radii.

  19. Crystal structure of rac-3-[2,3-bis-(phenyl-sulfan-yl)-3H-indol-3-yl]propanoic acid.

    Science.gov (United States)

    Noland, Wayland E; Brown, Christopher D; Bisel, Amanda M; Schneerer, Andrew K; Tritch, Kenneth J

    2015-11-01

    The title compound, C23H19NO2S2, was obtained as an unexpected regioisomer from an attempted synthesis of an inter-mediate for a substituent-effect study on ergot alkaloids. This is the first report of a 1H-indole mono-thio-ating at the 2- and 3-positions to give a 3H-indole. In the crystal, the acid H atom is twisted roughly 180° from the typical carb-oxy conformation and forms centrosymmetric O-H⋯N hydrogen-bonded dimers with the indole N atom of an inversion-related mol-ecule. Together with a weak C-H⋯O hydrogen bond involving the carbonyl O atom, chains are formed along [100].

  20. Crystal structure of dimethyl 2,5-bis-[(di-phen-oxy-phosphor-yl)-oxy]cyclo-hexa-1,4-diene-1,4-di-carboxyl-ate.

    Science.gov (United States)

    Gao, Lei; Ma, Zongshan; Yan, Hong

    2015-06-01

    In the title compound, C34H30O12P2, which was synthesized via the esterification of dimethyl 2,5-dioxo-1,4-cyclo-hexa-nedi-carboxyl-ate with diphenyl chloro-phosphate, the mol-ecule has crystallographic inversion symmetry. The dihedral angles between the plane of the cyclo-hexa-1,4-diene ring and those of the two benzene rings of the substituent phosphate groups are 41.0 (1) and 89.5 (1)°, while that with the ester group is 3.1 (3)°. In the crystal, only weak inter-molecular C-H⋯O hydrogen bonds are present.

  1. Crystal structure of 4-[1-(2-hy-droxy-prop-yl)-4,5-diphenyl-1H-imidazol-2-yl]benzoic acid.

    Science.gov (United States)

    Jasinski, Jerry P; Mohamed, Shaaban K; Akkurt, Mehmet; Abdelhamid, Antar A; Albayati, Mustafa R

    2015-02-01

    In the title compound, C25H22N2O3, the central imidazole ring makes dihedral angles of 48.43 (10), 20.23 (10) and 75.38 (11)° with the benzene ring and the two phenyl rings, respectively. The phenyl ring adjacent to the N-bonded 2-hy-droxy-propyl group shows the greatest twist, presumably to minimize steric inter-actions. In the crystal, mol-ecules are linked by O-H⋯N, O-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network. In addition, C-H⋯π inter-actions are also observed.

  2. Crystal structure of 1-ferrocenyl-2-(4-methyl-benzo-yl)spiro-[11H-pyrrolidizine-3,11'-indeno[1,2-b]quinoxaline].

    Science.gov (United States)

    Chandralekha, Kuppan; Gavaskar, Deivasigamani; Sureshbabu, Adukamparai Rajukrishnan; Lakshmi, Srinivasakannan

    2014-09-01

    In the title compound, [Fe(C5H5)(C34H28N3O)], the four-fused-rings system of the 11H-indeno-[1,2-b]quinoxaline unit is approximately planar [maximum deviation = 0.167 (4) Å] and forms a dihedral angle of 37.25 (6)° with the plane of the benzene ring of the methyl-benzoyl group. Both pyrrolidine rings adopt a twist conformation. An intra-molecular C-H⋯O hydrogen bond is observed. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions, forming double chains extending parallel to the c axis.

  3. Crystal structure of 4-{[(2,4-di-hydroxy-benzyl-idene)amino]-meth-yl}cyclo-hexane-carb-oxy-lic acid.

    Science.gov (United States)

    Danish, Muhammad; Akbar, Saba; Tahir, Muhammad Nawaz; Butt, Rabia Ayub; Ashfaq, Muhammad

    2015-12-01

    In the title compound, C15H19NO4, the cyclo-hexyl ring adopts a chair conformation with both exocyclic C-C bonds in equatorial orientations. The dihedral angle between the basal plane of cyclo-hexyl ring and the 2,4-di-hydroxy-benzaldehyde moiety is 84.13 (13)°. An intra-molecular O-H⋯N hydrogen bonds closes an S(6) ring. In the crystal, Oc-H⋯Op (c = carb-oxy-lic acid, p = phenol) hydrogen bonds link the mol-ecules into [100] C(13) chains whereas an Op-H⋯Oc hydrogen bond generates [101] C(15) chains. Together, these bonds generate (010) sheets incorporating R 2 (2)(20) loops. Weak C-H⋯O and C-H⋯π inter-actions also occur.

  4. Crystal structure of 7-iodo-4-oxo-4H-chromene-3-carbaldehyde.

    Science.gov (United States)

    Ishikawa, Yoshinobu

    2016-12-01

    In the title compound, C10H5IO3, an iodinated 3-formyl-chromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0344 Å), with the largest deviation from the least-squares plane [0.101 (3) Å] being found for the formyl O atom. In the crystal, mol-ecules are linked through stacking inter-actions [centroid-centroid distance between the benzene rings = 3.700 (3) Å] and C-H⋯O hydrogen bonds. Halogen bonds between the I atoms at 7-position and the formyl O atoms [I1⋯O3 = 3.056 (2) Å, C6-I1⋯O3 = 173.18 (8)° and I1⋯O3-C10 = 111.12 (18)°] are also formed along [110], resulting in sheets perpendicular to the c axis, constructed by C-H⋯O hydrogen bonds and I⋯O halogen bonds.

  5. Crystal structure of 4-oxo-4H-chromene-3-carb-oxy-lic acid.

    Science.gov (United States)

    Ishikawa, Yoshinobu

    2015-08-01

    In the title compound, C10H6O4, also known as 3-carb-oxy-chromone, the non-H atoms of the chromone ring are essentially coplanar (r.m.s. deviation = 0.0057 Å), with the maximum deviation from their least-squares plane [0.011 (2) Å] being for a pyran C atom. The dihedral angle between the fused ring and plane of the carb-oxy group is 3.06 (2)°. An intra-molecular hydrogen bond is formed between the ring carbonyl O atom and the carb-oxy O-H atom, closing an S(6) loop. In the crystal, mol-ecules are assembled by stacking inter-actions [centroid-centroid distance between the benzene and pyran rings = 3.844 (3) Å] and C-H⋯O hydrogen bonds, generating a three-dimensional network. Short contacts are also observed between the carb-oxy O and C atoms [C=O⋯C=O = 3.002 (3) Å].

  6. Crystal structure of a photobiologically active brominated angular pyran-ocoumarin: bromo-hy-droxy-seselin.

    Science.gov (United States)

    Bauri, A K; Foro, Sabine; Rahman, A F M Mustafizur

    2017-03-01

    The title compound, C14H13BrO3 [systematic name: rac-(9S,10R)-9-bromo-10-hy-droxy-8,8-dimethyl-9,10-di-hydro-2H,8H-pyrano[2,3-f]chromen-2-one], is a substituted pyran-ocoumarin, obtained by bromination of seselin [8,8-dimethyl-2H,8H-pyrano[2,3-f]chromen-2-one], which was isolated from the Indian herb Trachyspermum stictocarpum (Aajmod). The pyrano ring has a distorted half-chair conformation and its mean plane is inclined to the coumarin mean plane by 1.6 (2)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with an R(2)2(16) ring motif. The dimers stack along the a-axis direction and are linked by offset π-π inter-actions, forming columns [inter-centroid distance = 3.514 (4) Å].

  7. Structural colours through photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    McPhedran, R.C.; Nicorovici, N.A.; McKenzie, D.R.; Rouse, G.W.; Botten, L.C.; Welch, V.; Parker, A.R.; Wohlgennant, M.; Vardeny, V

    2003-10-01

    We discuss two examples of living creatures using photonic crystals to achieve iridescent colouration. The first is the sea mouse (Aphroditidae, Polychaeta), which has a hexagonal close packed structure of holes in its spines and lower-body felt, while the second is the jelly fish Bolinopsis infundibulum, which has an oblique array of high index inclusions in its antennae. We show by measurements and optical calculations that both creatures can achieve strong colours despite having access only to weak refractive index contrast.

  8. THE CRYSTAL STRUCTURE OF ANTIMONY (III) SULFOBROMIDE, SBSBR,

    Science.gov (United States)

    ANTIMONY COMPOUNDS, *SULFUR COMPOUNDS, CRYSTAL STRUCTURE , CRYSTAL STRUCTURE , BROMIDES, SYMMETRY(CRYSTALLOGRAPHY), FOURIER ANALYSIS, MOLECULAR STRUCTURE, CRYSTAL LATTICES, CHEMICAL BONDS, X RAY DIFFRACTION.

  9. Crystal structure of bis-[(acetato-κO)(imidazolidine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-μ-imidazol-idine-2-thione-κ(4) S:S-bis-[(imidazol-id-ine-2-thione-κS)bis-(tri-phenyl-phosphane-κP)silver(I)] di-acetate aceto-nitrile disolvate tetra-hydrate.

    Science.gov (United States)

    Nimthong-Roldán, Arunpatcha; Ratthiwan, Janejira; Lakmas, Sawanya; Wattanakanjana, Yupa

    2016-04-01

    In the title compound, [Ag2(C3H6N2S)4(C18H15P)2](C2H3O2)2·[Ag(C2H3O2)(C3H6N2S)(C18H15P)2]2·2C2H3N·4H2O, the Ag(I) ion in the mononuclear neutral complex exhibits a distorted tetra-hedral environment with coordination by two P atoms from tri-phenyl-phosphane (PPh3) ligands, one S atom of an imidazolidine-2-thione (etu) ligand and one O atom of an acetate anion. The binuclear cationic complex comprises two inversion-related [Ag(C3H6N2S)2(C18H15P)] units with Ag(I) ions bridged by two S atoms from etu ligands forming a four-membered Ag-S-Ag-S ring. Each Ag(I) ion is coordinated by a P atom of a PPh3 ligand, two S atoms of bridging etu ligands and the terminal S atom of an etu ligand in a distorted tetra-hedral environment. In the crystal, the mononuclear complex is linked to lattice water mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a chain along [100]. In addition, the binuclear complex mol-ecules are connected to acetate anions and lattice water mol-ecules via O-H⋯O, N-H⋯O and O-H⋯S hydrogen bonds, also along [100].

  10. Pattern information extraction from crystal structures

    OpenAIRE

    Okuyan, Erhan

    2005-01-01

    Cataloged from PDF version of article. Determining crystal structure parameters of a material is a quite important issue in crystallography. Knowing the crystal structure parameters helps to understand physical behavior of material. For complex structures, particularly for materials which also contain local symmetry as well as global symmetry, obtaining crystal parameters can be quite hard. This work provides a tool that will extract crystal parameters such as primitive vect...

  11. Crystal structure of gold hydride

    Energy Technology Data Exchange (ETDEWEB)

    Degtyareva, Valentina F., E-mail: degtyar@issp.ac.ru

    2015-10-05

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions.

  12. Crystal structure of (2,11-di-aza-[3.3](2,6)pyridino-phane-κ (4) N,N',N'',N''')(1,6,7,12-tetra-aza-perylene-κ (2) N (1),N (12))ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile 1.422-solvate.

    Science.gov (United States)

    Brietzke, Thomas; Rottke, Falko Otto; Kelling, Alexandra; Schilde, Uwe; Holdt, Hans-Jürgen

    2014-10-01

    In the title compound, [Ru(C14H16N4)(C16H8N4)](PF6)2·1.422CH3CN, discrete dimers of complex cations, [Ru(L-N4H2)tape](2+) are formed {L-N4H2 = 2,11-di-aza-[3.3](2,6)pyridino-phane; tape = 1,6,7,12-tetra-aza-perylene}, held together by π-π stacking inter-actions via the tape ligand moieties with a centroid-centroid distance of 3.49 (2) Å, assisted by hydrogen bonds between the non-coordinating tape ligand α,α'-di-imine unit and the amine proton of a 2,11-di-aza-[3.3](2,6)-pyridino-phane ligand of the opposite complex cation. The combination of these inter-actions leads to an unusual nearly face-to-face π-π stacking mode. Additional weak C-H⋯N, C-H⋯F, N-H⋯F and P-F⋯π-ring (tape, py) (with F⋯centroid distances of 2.925-3.984 Å) inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry, particularly manifested by the Namine-Ru-Namine angle of 153.79 (10)°. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by aceto-nitrile solvent mol-ecules of crystallization. Disorder was observed for both the hexa-fluorido-phosphate anions as well as the aceto-nitrile solvate mol-ecules, with occupancies for the major moieties of 0.801 (6) for one of the PF6 anions, and a shared occupancy of 0.9215 (17) for the second PF6 anion and a partially occupied aceto-nitrile mol-ecule. A second CH3CN mol-ecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

  13. Bis(2-hydroxy-benzaldehyde oxime) O,O'-butane-1,4-diyldicarbonyl ether.

    Science.gov (United States)

    Etemadi, Bijan; Kia, Reza; Sharghi, Hashem; Hosseini Sarvari, Mona

    2009-05-20

    The mol-ecule of the title compound, C(20)H(20)N(2)O(6), lies across a crystallographic inversion centre, the asymmetric unit comprising one half-mol-ecule. An intra-molecular O-H⋯N hydrogen bond generates a six-membered ring, producing an S(6) ring motif. Pairs of inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into a layer with R(2) (2)(38) ring motif. The crystal structure is further stabilized by the inter-molecular C-H⋯π inter-actions.

  14. Crystal structure of (3S*,4R*)-4-fluoro-3-(4-meth-oxy-phen-yl)-1-oxo-2-phenyl-1,2,3,4-tetra-hydro-iso-quinoline-4-carb-oxy-lic acid.

    Science.gov (United States)

    Lehmann, Anna; Lechner, Lisa; Radacki, Krzysztof; Braunschweig, Holger; Holzgrabe, Ulrike

    2017-06-01

    The title compound, C23H18FNO4, crystallized as a racemate. It exhibits a cis conformation with respect to the F atom and the methine H atom. The piperidine ring has a screw-boat conformation. The meth-oxy-phenyl ring and the phenyl ring are inclined to the mean plane of the iso-quinoline ring system by 89.85 (4) and 46.62 (5)°, respectively, and by 78.15 (5)° to one another. In the crystal, mol-ecules are linked by an O-H⋯O hydrogen bond forming chains propagating along the a-axis direction. The chains are linked by C-H⋯F hydrogen bonds, forming layers lying parallel to the ab plane.

  15. (E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-[3-meth-oxy-4-(meth-oxy-meth-oxy)phen-yl]prop-2-en-1-one.

    Science.gov (United States)

    Chang, Liu-Shuan; Li, Chen-Yang; Zhao, Yan-Mei; Xu, Fang; Gu, Zheng-Yi

    2011-11-01

    The title compound, C(22)H(26)O(9), crystallizes with two independent mol-ecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intra-molecular O-H⋯O hydrogen bond occurs in each mol-ecule. Inter-molecular C-H⋯O hydrogen bonds stabilize the crystal structure.

  16. Crystal structure of fiber structured pentacene thin films

    OpenAIRE

    2007-01-01

    This PhD thesis presents a technique based on the grazing incidence crystal truncation rod (GI-CTR) X-ray diffraction method used to solve the crystal structure of substrate induced fiber structured organic thin films. The crystal structures of pentacene thin films grown on technologically relevant gate dielectric substrates are reported. It is widely recognized, that the intrinsic charge transport properties in organic thin film transistors (OTFTs) depend strongly on the crystal structur...

  17. Crystal growth and structural analysis of zirconium sulphoselenide single crystals

    Indian Academy of Sciences (India)

    K R Patel; R D Vaidya; M S Dave; S G Patel

    2008-08-01

    A series of zirconium sulphoselenide (ZrSSe3–, where = 0, 0.5, 1, 1.5, 2, 2.5, 3) single crystals have been grown by chemical vapour transport technique using iodine as a transporting agent. The optimum condition for the growth of these crystals is given. The stoichiometry of the grown crystals were confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and the structural characterization was accomplished by X-ray diffraction (XRD) studies. The crystals are found to possess monoclinic structure. The lattice parameters, volume, particle size and X-ray density have been carried out for these crystals. The effect of sulphur proportion on the lattice parameter, unit cell volume and X-ray density in the series of ZrSSe3– single crystals have been studied and found to decrease in all these parameters with rise in sulphur proportion. The grown crystals were examined under optical zoom microscope for their surface topography study. Hall effect measurements were carried out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are -type in nature. The conductivity is found to decrease with increase of sulphur content in the ZrSSe3– series. The electrical resistivity parallel to c-axis as well as perpendicular to -axis have been carried out in the temperature range 303–423 K. The results obtained are discussed in detail.

  18. Influence of microgravity on protein crystal structures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Structural determination and comparison of microgravity and ground grown protein crystals have been carried out in order to investigate the effect of microgravity on the structure of protein crystals. Following the structural studies on the hen egg-white lysozyme cystals grown in space and on the ground, the same kind of comparative studies was performed with acidic phospholipase A2 crystals grown in different gravities. Based on the results obtained so far, a conclusion could be made that microgravity might not be strong enough to change the conformation of polypeptide chain of proteins, but it may improve the bound waters' structure, and this might be an important factor for microgravity to improve the protein crystal quality. In addition, the difference in the improvement between the two kinds of protein crystals may imply that the degree of improvement of a protein crystal in microgravity may be related to the solvent content in the protein crystal.

  19. Crystal structures of a copper(II) and the isotypic nickel(II) and palladium(II) complexes of the ligand (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-ol.

    Science.gov (United States)

    Chetioui, Souheyla; Rouag, Djamil-Azzeddine; Djukic, Jean-Pierre; Bochet, Christian G; Touzani, Rachid; Bailly, Corinne; Crochet, Aurélien; Fromm, Katharina M

    2016-08-01

    In the copper(II) complex, bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naph-thalen-2-olato}copper(II), [Cu(C16H8Br3N2O)2], (I), the metal cation is coord-inated by two N atoms and two O atoms from two bidentate (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olate ligands, forming a slightly distorted square-planar environment. In one of the ligands, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 37.4 (5)°, creating a weak intra-molecular Cu⋯Br inter-action [3.134 (2) Å], while in the other ligand, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 72.1 (6)°. In the isotypic nickel(II) and palladium(II) complexes, namely bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}nickel(II), [Ni(C16H8Br3N2O)2], (II), and bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}palladium(II), [Pd(C16H8Br3N2O)2], (III), respectively, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries. The tri-bromo-benzene rings are inclined to the naphthalene ring systems by 80.79 (18)° in (II) and by 80.8 (3)° in (III). In the crystal of (I), mol-ecules are linked by C-H⋯Br hydrogen bonds, forming chains along [010]. The chains are linked by C-H⋯π inter-actions, forming sheets parallel to (011). In the crystals of (II) and (III), mol-ecules are linked by C-H⋯π inter-actions, forming slabs parallel to (10-1). For the copper(II) complex (I), a region of disordered electron density was corrected for using the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The formula mass and unit-cell characteristics of the disordered solvent mol-ecules were not taken into account during refinement.

  20. Predicting crystal structures of organic compounds.

    Science.gov (United States)

    Price, Sarah L

    2014-04-07

    Currently, organic crystal structure prediction (CSP) methods are based on searching for the most thermodynamically stable crystal structure, making various approximations in evaluating the crystal energy. The most stable (global minimum) structure provides a prediction of an experimental crystal structure. However, depending on the specific molecule, there may be other structures which are very close in energy. In this case, the other structures on the crystal energy landscape may be polymorphs, components of static or dynamic disorder in observed structures, or there may be no route to nucleating and growing these structures. A major reason for performing CSP studies is as a complement to solid form screening to see which alternative packings to the known polymorphs are thermodynamically feasible.

  1. Crystal structure of rac-(3a'R,9a'R)-3a'-(indol-3-yl)-1',2',3',3a',4',9a'-hexa-hydro-spiro-[cyclo-pentane-1,9'-penta-leno[1,2-b]indole] p-xylene hemisolvate.

    Science.gov (United States)

    Noland, Wayland E; Worth, Matthew A; Schneerer, Andrew K; Paal, Courtney L; Tritch, Kenneth J

    2015-05-01

    The title compound, C26H26N2·0.5C8H10, is the first reported characterized 2:2 product from acid-catalyzed condensation of indole with cyclo-penta-none and no other 2:2 products were observed. Recrystallization from p-xylene gave the title hemisolvate with the p-xylene mol-ecule located about an inversion center. The terminal penta-lene ring is envelope-flap disordered at the C atom farthest from the skeletal indole unit, with a refined occupancy ratio of 0.819 (4):0.181 (4). The major component has this C atom bent away from the spiro-fused cyclo-pentane ring. In the crystal, mol-ecules are connected by N-H⋯π inter-actions, forming chains along [100], and N-H⋯π and C-H⋯π inter-actions, forming chains along [001], which results in the formation of slabs parallel to (010).

  2. Crystal structure of hexa-aqua-nickel(II) bis-{5-bromo-7-[(2-hy-droxy-eth-yl)amino]-1-methyl-6-oxido-quinolin-1-ium-3-sulfonate} monohydrate.

    Science.gov (United States)

    Le Thi Hong, Hai; Nguyen Thi Ngoc, Vinh; Do Thi Van, Anh; Van Meervelt, Luc

    2016-09-01

    The asymmetric unit of the title compound, [Ni(H2O)6](C12H12BrN2O5S)2·H2O, contains a half hexa-aqua-nickel(II) complex cation with the Ni(II) ion lying on an inversion center, one 5-bromo-7-[(2-hy-droxy-eth-yl)amino]-1-methyl-6-oxido-quinolin-1-ium-3-sulfonate (QAO) anion and a half lattice water mol-ecule on a twofold rotation axis. In the crystal, QAO anions are stacked in a column along the c axis by π-π stacking inter-actions [centroid-centroid distances 3.5922 (10)-3.7223 (11) Å]. The columns are inter-linked by hexa-aqua-nickel(II) cations through O-H⋯O and N-H⋯O hydrogen bonds.

  3. Crystal structure analysis of intermetallic compounds

    Science.gov (United States)

    Conner, R. A., Jr.; Downey, J. W.; Dwight, A. E.

    1968-01-01

    Study concerns crystal structures and lattice parameters for a number of new intermetallic compounds. Crystal structure data have been collected on equiatomic compounds, formed between an element of the Sc, Ti, V, or Cr group and an element of the Co or Ni group. The data, obtained by conventional methods, are presented in an easily usable tabular form.

  4. (E)-1-Benzyl-idene-2,2-diphenyl-hydrazine.

    Science.gov (United States)

    Mendoza, Angel; Meléndrez-Luevano, Ruth; Cabrera-Vivas, Blanca M; Lozano-Márquez, Claudia D; Carranza, Vladimir

    2012-02-01

    The asymmetric unit of the title compound, C(19)H(16)N(2), contains two independent mol-ecules, both of which show an E configuration with respect to the C=N bond. The dihedral angles between the phenyl rings bonded to the hydrazine group are 81.00 (10) and 88.34 (8)° in the two mol-ecules. Inter-molecular C-H⋯π inter-actions are observed in the crystal structure.

  5. Crystal structure of tetra-kis-[μ2-2-(di-methyl-amino)-ethano-lato-κ(3) N,O:O]di-μ3-hydroxido-di-thio-cyanato-κ(2) N-dichromium(III)dilead(II) di-thio-cyanate aceto-nitrile monosolvate.

    Science.gov (United States)

    Rusanova, Julia A; Semenaka, Valentyna V; Omelchenko, Irina V

    2016-04-01

    The tetra-nuclear complex cation of the title compound, [Cr2Pb2(NCS)2(OH)2(C4H10NO)4](SCN)2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6 cage with a central four-membered Cr2O2 ring. The Cr(III) ion is coordinated in a distorted octa-hedron, which involves two N atoms of one bidentate ligand and one thio-cyanate anion, two μ2-O atoms of 2-(di-methyl-amino)-ethano-late ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the Pb(II) ion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb⋯S inter-actions involving the coordinating and non-coordinating thio-cyanate anions are observed. In the crystal, the complex cations are linked through the thio-cyanate anions via the Pb⋯S inter-actions and O-H⋯N hydrogen bonds into chains along the c axis. The chains are further linked together via S⋯S contacts. The contribution of the disordered solvent aceto-nitrile mol-ecule was removed with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON. The solvent is included in the reported mol-ecular formula, weight and density.

  6. THE CRYSTAL STRUCTURE OF ALPHA-DIMETHYLTELLURIUM DICHLORIDE,

    Science.gov (United States)

    TELLURIUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, CRYSTAL STRUCTURE , CRYSTAL STRUCTURE , CHLORIDES, SYMMETRY(CRYSTALLOGRAPHY), MOLECULAR STRUCTURE, CHEMICAL BONDS, X RAY DIFFRACTION, ANISOTROPY, FOURIER ANALYSIS.

  7. Crystal Structure of Isoquinoline Derivatives

    Institute of Scientific and Technical Information of China (English)

    LUO Mei; ZHANG Jia-Hai; ZHOU Shi-Ming; SUN Jie; YIN Hao; HU Ke-Liang

    2011-01-01

    The chiral compound 5H-imidazol[2,3-b]isoquinoline-l-ethanol-5-one-1,2, 3, 10b-tetrahydro- β(S)-phenyl-3(S)-phenyl was synthesized from the direct condensation of 2- cyanophenyacetonitrile with optically active (S)-(+)-2-phenylglycinol in chlorobenzene under dry, anaerobic conditions. ZnCl2 was used as a Lewis acid catalyst in this reaction, and the structure of this compound was determined by X-ray diffraction, NMR, MS and IR. Crystal data of the title compound: C25H22N2O2, Mr = 382.45, P 21 21 21, a = 5.341(5), b = 16.735(5), c = 22.129(5) A, γ = 90°, V = 1978(2)A^3, Z = 4, Dc = 1.284 g/cm^3, the final R = 0.0321 for 2269 observed reflections with I 〉 2 σ(I) and Rw = 0.0771 for all data.

  8. Crystal structure of 2-pentyloxybenzamide

    Directory of Open Access Journals (Sweden)

    Bernhard Bugenhagen

    2014-10-01

    Full Text Available In the title molecule, C12H17NO2, the amide NH2 group is oriented toward the pentyloxy substituent and an intramolecular N—H...O hydrogen bond is formed with the pentyloxy O atom. The benzene ring forms dihedral angles of 2.93 (2 and 5.60 (2° with the amide group and the pentyloxy group mean planes, respectively. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers with their molecular planes parallel, but at an offset of 0.45 (1 Å to each other. These dimers are ordered into two types of symmetry-related columns extended along the a axis, with the mean plane of one set of dimers in a column approximately parallel to (121 and the other in a column approximately parallel to (1-21. The two planes form a dihedral angle of 85.31 (2°, and are linked via C—H...O hydrogen bonds and C—H...π interactions, forming a three-dimensional framework structure.

  9. Method of fabricating patterned crystal structures

    KAUST Repository

    Yu, Liyang

    2016-12-15

    A method of manufacturing a patterned crystal structure for includes depositing an amorphous material. The amorphous material is modified such that a first portion of the amorphous thin-film layer has a first height/volume and a second portion of the amorphous thin-film layer has a second height/volume greater than the first portion. The amorphous material is annealed to induce crystallization, wherein crystallization is induced in the second portion first due to the greater height/volume of the second portion relative to the first portion to form patterned crystal structures.

  10. synthesis, characterization and crystal structure of a ...

    African Journals Online (AJOL)

    Preferred Customer

    Crystal and molecular structure of the complex ... Coordination chemistry of molybdenum(VI) has attracted considerable attention due to its biochemical significance [1-3] as well as for the efficient catalytic properties in several organic.

  11. Pattern information extraction from crystal structures

    Science.gov (United States)

    Okuyan, Erhan; Güdükbay, Uğur; Gülseren, Oğuz

    2007-04-01

    Determining the crystal structure parameters of a material is an important issue in crystallography and material science. Knowing the crystal structure parameters helps in understanding the physical behavior of material. It can be difficult to obtain crystal parameters for complex structures, particularly those materials that show local symmetry as well as global symmetry. This work provides a tool that extracts crystal parameters such as primitive vectors, basis vectors and space groups from the atomic coordinates of crystal structures. A visualization tool for examining crystals is also provided. Accordingly, this work could help crystallographers, chemists and material scientists to analyze crystal structures efficiently. Program summaryTitle of program: BilKristal Catalogue identifier: ADYU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYU_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: None Programming language used: C, C++, Microsoft .NET Framework 1.1 and OpenGL Libraries Computer: Personal Computers with Windows operating system Operating system: Windows XP Professional RAM: 20-60 MB No. of lines in distributed program, including test data, etc.:899 779 No. of bytes in distributed program, including test date, etc.:9 271 521 Distribution format:tar.gz External routines/libraries: Microsoft .NET Framework 1.1. For visualization tool, graphics card driver should also support OpenGL Nature of problem: Determining crystal structure parameters of a material is a quite important issue in crystallography. Knowing the crystal structure parameters helps to understand physical behavior of material. For complex structures, particularly, for materials which also contain local symmetry as well as global symmetry, obtaining crystal parameters can be quite hard. Solution method: The tool extracts crystal parameters such as primitive vectors, basis vectors and identify the space group from

  12. Photonic-crystal fibre: Mapping the structure

    DEFF Research Database (Denmark)

    Markos, Christos

    2015-01-01

    The demonstration of real-time and non-destructive Doppler-assisted tomography of the internal structure of photonic-crystal fibres could aid the fabrication of high-quality fibres with enhanced performance.......The demonstration of real-time and non-destructive Doppler-assisted tomography of the internal structure of photonic-crystal fibres could aid the fabrication of high-quality fibres with enhanced performance....

  13. Crystal structure of meteoritic schreibersites: determination of absolute structure

    Science.gov (United States)

    Skála, Roman; Císařová, Ivana

    Minerals of the schreibersite nickelphosphide series (Fe,Ni)3P crystallize in the non-centrosymmetric space group Ibar 4. As a consequence, they can possess two different spatial arrangements of the constituting atoms within the unit cell, related by the inversion symmetry operation. Here, we present the crystal structure refinements from single crystal X-ray diffraction data for schreibersite grains from iron meteorites Acuña, Carlton, Hex River Mts. (three different crystals), Odessa (two different crystals), Sikhote Alin, and Toluca aiming for the determination of the absolute structure of the examined crystals. The crystals studied cover the composition range from 58 mol% to 80 mol% Fe3P end-member. Unit-cell parameter a and volume of the unit cell V, as well as certain topological structural parameters tightly correlate with Fe3P content. Unit-cell parameter c, on the other hand, does not show such strong correlation. Eight of the nine crystal structure refinements allowed unambiguous absolute structure assignment. The single crystal extracted from Toluca is, however, of poor quality and consequently the structure refinement did not provide as good results as the rest of the materials. Also, this crystal has only weak inversion distinguishing power to provide unequivocal absolute structure determination. Six of the eight unambiguous absolute structure determinations indicated inverted atomic arrangement compared to that reported in earlier structure refinements (here called standard). Only two grains, one taken from Odessa iron and the other from the Hex River Mts. meteorite, reveal the dominance of standard crystal structure setting.

  14. Structures of cyano-biphenyl liquid crystals

    Science.gov (United States)

    Chu, Yuan-Chao; Tsang, Tung; Rahimzadeh, E.; Yin, L.

    1989-01-01

    The structures of p-alkyl- p'-cyano- bicyclohexanes, C(n)H(2n+1) (C6H10)(C6H10) CN (n-CCH), and p-alkyl- p'-cyano- biphenyls, C(n)H(2n+1) (C6H4)(C6H4) CN (n-CBP), were studied. It is convenient to use an x ray image intensification device to search for symmetric x ray diffraction patterns. Despite the similarities in molecular structures of these compounds, very different crystal structures were found. For the smectic phase of 2CCH, the structure is close to rhombohedral with threefold symmetry. In contrast, the structure is close to hexagonal close-packed with two molecules per unit cell for 4CCH. Since intermolecular forces may be quite weak for these liquid crystals systems, it appears that crystal structures change considerably when the alkyl chain length is slightly altered. Different structures were also found in the crystalline phase of n-CBP for n = 6 to 9. For n = 7 to 9, the structures are close to monclinic. The structures are reminiscent of the smectic-A liquid crystal structures with the linear molecules slightly tilted away from the c-axis. In contrast, the structure is quite different for n = 6 with the molecules nearly perpendicular to the c-axis.

  15. Nucleation and structural growth of cluster crystals

    CERN Document Server

    Leitold, Christian

    2016-01-01

    We study the nucleation of crystalline cluster phases in the generalized exponential model with exponent n=4. Due to the finite value of this pair potential for zero separation, at high densities the system forms cluster crystals with multiply occupied lattice sites. Here, we investigate the microscopic mechanisms that lead to the formation of cluster crystals from a supercooled liquid in the low-temperature region of the phase diagram. Using molecular dynamics and umbrella sampling, we calculate the free energy as a function of the size of the largest crystalline nucleus in the system, and compare our results with predictions from classical nucleation theory. Employing bond-order parameters based on a Voronoi tessellation to distinguish different crystal structures, we analyze the average composition of crystalline nuclei. We find that even for conditions where a multiply-occupied fcc crystal is the thermodynamically stable phase, the nucleation into bcc cluster crystals is strongly preferred. Furthermore, w...

  16. Crystal structure from one-electron theory

    DEFF Research Database (Denmark)

    Skriver, H. L.

    1985-01-01

    The authors have studied the crystal structure of all the 3d, 4d, and 5d transition metals at zero pressure and temperature by means of the linear muffin-tin orbital method and Andersen's force theorem. They find that, although the structural energy differences seem to be overestimated by the the......The authors have studied the crystal structure of all the 3d, 4d, and 5d transition metals at zero pressure and temperature by means of the linear muffin-tin orbital method and Andersen's force theorem. They find that, although the structural energy differences seem to be overestimated...... by the theory, the predicted crystal structures are in accord with experiment in all cases except 79Au. In addition, they have investigated the effect of pressure upon the alkali metals (3Li, 11Na, 37Rb, 55Cs) and selected lanthanide metals (57La, 58Ce, 71Lu) and actinide metals (90Th, 91Pa). In these cases...

  17. Structure of crystals of hard colloidal spheres

    Energy Technology Data Exchange (ETDEWEB)

    Pusey, P.N.; van Megen, W.; Bartlett, P.; Ackerson, B.J.; Rarity, J.G.; Underwood, S.M. (Royal Signals and Radar Establishment, Malvern, WR14 3PS, United Kingsom (GB) Department of Applied Physics, Royal Melbourne Institute of Technology, Melbourne, Victoria, Australia School of Chemistry, Bristol University, Bristol, BS8 1TS, United Kingdom Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078)

    1989-12-18

    We report light-scattering measurements of powder diffraction patterns of crystals of essentially hard colloidal spheres. These are consistent with structures formed by stacking close-packed planes of particles in a sequence of permitted lateral positions, {ital A},{ital B},{ital C}, which shows a high degree of randomness. Crystals grown slowly, while still containing many stacking faults, show a tendency towards face-centered-cubic packing: possible explanations for this observation are discussed.

  18. Crystal Structure of Macrocalyxin J

    Institute of Scientific and Technical Information of China (English)

    HE Shan; WU Bin; SHI Hao; SUN Cui-Rong

    2007-01-01

    The title compound, (1α,6β, 1 1β, 14α)-1,7:6,20-diepoxy-6,1 1-dihydroxy- 6,7-secoent- kaur-1 6-ene-7,15-dione-14-acetate (macrocalyxin J), is a diterpenoid which was isolated from the leaves of Rabdosia macrocalyx and characterized by single-crystal X-ray diffraction. It crystallizes in orthorhombic, spac e group P212121 with a = 9.3608(8), b = 14.9787(12), c = 15.5750(13)(A), Z = 4, V = 2183.8(3) (A)3, C22H30O9, Mr = 438.46, Dc = 1.334 g/m3, μ(MoKα) = 0.103 mm-1,F(000) = 936, the final R = 0.0532 and wR = 0.1262 for 2252 observed reflections (I > 2σ(I)). In the molecule, three six-membered rings adopt chair, boat and slightly distorted boat conformations,respectively, while both five-membered rings have approximate envelope conformations.

  19. Crystal structure of levomepromazine maleate

    Directory of Open Access Journals (Sweden)

    Gyula Tamás Gál

    2016-05-01

    Full Text Available The asymmetric unit of the title salt, C19H25N2OS+·C4H3O4− [systematic name: (S-3-(2-methoxyphenothiazin-10-yl-N,N,2-trimethylpropanaminium hydrogen maleate], comprises two (S-levomepromazine cations and two hydrogen maleate anions. The conformations of the two cations are similar. The major difference relates to the orientation of the methoxy substituent at the phenothiazine ring system. The crystal components form a three-dimensional supramolecular network via N—H...O, C—H...O and C—H...π interactions. A comparison of the conformations of the levomepromazine cations with those of the neutral molecule and similar protonated molecules reveals significant conformational flexibility of the phenothiazine ring system and the substituent at the phenothiazine N atom.

  20. Crystal structure of 3-(hydroxymethylchromone

    Directory of Open Access Journals (Sweden)

    Yoshinobu Ishikawa

    2015-07-01

    Full Text Available In the title compound, C10H8O3 (systematic name 3-hydroxymethyl-4H-chromen-4-one, the fused-ring system is slightly puckered [dihedral angle between the rings = 3.84 (11°]. The hydroxy O atom deviates from the heterocyclic ring by 1.422 (1 Å. In the crystal, inversion dimers linked by pairs of O—H...O hydrogen bonds generate R22(12 loops. The dimers are linked by aromatic π–π stacking [shortest centroid–centroid distance = 3.580 (3 Å], and C—H...O hydrogen bonds, generating a three-dimensional network.

  1. Crystal structure of 9-methacryloylanthracene

    Directory of Open Access Journals (Sweden)

    Aditya Agrahari

    2015-04-01

    Full Text Available In the title compound, C18H14O, with systematic name 1-(anthracen-9-yl-2-methylprop-2-en-1-one, the ketonic C atom lies 0.2030 (16 Å out of the anthryl-ring-system plane. The dihedral angle between the planes of the anthryl and methacryloyl moieties is 88.30 (3° and the stereochemistry about the Csp2—Csp2 bond in the side chain is transoid. In the crystal, the end rings of the anthryl units in adjacent molecules associate in parallel–planar orientations [shortest centroid–centroid distance = 3.6320 (7 Å]. A weak hydrogen bond is observed between an aromatic H atom and the O atom of a molecule displaced by translation in the a-axis direction, forming sheets of parallel-planar anthryl groups packing in this direction.

  2. Test techniques for mol ecul ar biol 0gy 0f entomopathogenic fungi%虫生真菌的分子生物学检测技术

    Institute of Scientific and Technical Information of China (English)

    林华峰; 胡萃

    2001-01-01

    线粒体DNA探针、核糖体RNA编码DNA序列分析、随机扩增多态性DNA-聚合酶链式反应、基因组DNA探针和电泳核型分析,五类分子生物学技术在虫生真菌研究中已有应用.本文对此作了介绍,着重阐述了RAPD-PCR技术的特点及其使用此技术的研究成果.

  3. The crystal structure and crystal chemistry of fernandinite and corvusite

    Science.gov (United States)

    Evans, H.T.; Post, J.E.; Ross, D.R.; Nelen, J.A.

    1994-01-01

    Using type material of fernandinite from Minasragra, Peru, and corvusite from the Jack Claim, La Sal Mountains, Utah, the properties and crystal chemistry of these minerals have been determined by Rietveld analysis of the powder X-ray-diffraction patterns. The crystal structure of both species is isotypic with the V2O5 -type layer first found for ??-Ag0.68V2O5; it consists of chains of VO6 octahedra linked by opposite corners (parallel to b) condensed by edge-sharing to form the layer. The vanadium has average valence 4.8, and the resulting layer-charge is balanced by varying amounts of Ca, Na, and K in the interlayer region accompanied by labile water. This study has confirmed the validity of fernandinite as a unique mineral species. It is closely related to corvusite, from which it is distinguished on the basis of the dominant interlayer cation: Ca for fernandinite, Na for curvusite. -Authors

  4. Redetermined structure, inter-molecular inter-actions and absolute configuration of royleanone.

    Science.gov (United States)

    Fun, Hoong-Kun; Chantrapromma, Suchada; Salae, Abdul Wahab; Razak, Ibrahim Abdul; Karalai, Chatchanok

    2011-05-01

    The structure of the title diterpenoid, C(20)H(28)O(3), {systematic name: (4bS,8aS)-3-hy-droxy-2-isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octa-hydro-phenanthrene-1,4-dione} is confirmed [Eugster et al. (1993 ▶). Private communication (refcode HACGUN). CCDC, Union Road, Cambridge] and its packing is now described. Its absolute structure was established by refinement against data collected with Cu radiation: the two stereogenic centres both have S configurations. One cyclo-hexane ring adopts a chair conformation whereas the other cyclo-hexane ring is in a half-chair conformation and the benzoquinone ring is slightly twisted. An intra-molecular O-H⋯O hydrogen bond generates an S(5) ring motif. In the crystal, mol-ecules are linked into chains along [010] by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions. The packing also features C⋯O [3.131 (3) Å] short contacts.

  5. Lessons from crystal structures of kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Frydenvang, Karla Andrea; Pickering, Darryl S

    2017-01-01

    structure and how they bind agonists, antagonists and ions. The first structure of the ligand-binding domain of the GluK1 subunit was reported in 2005, seven years after publication of the crystal structure of a soluble construct of the ligand-binding domain of the AMPA-type subunit GluA2. Today, a full......-length structure has been determined of GluK2 by cryo electron microscopy to 7.6 Å resolution as well as 84 high-resolution crystal structures of N-terminal domains and ligand-binding domains, including agonist and antagonist bound structures, modulatory ions and mutations. However, there are still many unanswered...

  6. Crystal structure of putrescine aspartic acid complex

    OpenAIRE

    Ramaswamy, S.; Murthy, MRN

    1990-01-01

    Polyamines, putrescine, spermidine and spermine are ubiquitous biogenic cations believed to be important for a variety of cellular processes. In order to obtain structural information on the interaction of these amines with other biomolecules, the structure of a complex of putrescine with aspartic acid was determined using single crystal X-ray diffraction methods. The crystals belong monoclinic space group $C_2$ with $a = 21.504 \\AA$, $b = 4.779 \\AA$, $c = 8.350 \\AA$ and $\\beta = {97.63}^{\\ci...

  7. Crystal structure of canagliflozin hemihydrate

    Directory of Open Access Journals (Sweden)

    Kai-Hang Liu

    2016-05-01

    Full Text Available There are two canagliflozin molecules (A and B and one water molecule in the asymmetric unit of the title compound, C24H25FO5S·0.5H2O [systematic name: (2S,3R,4R,5S,6R-2-(3-{[5-(4-fluorophenylthiophen-2-yl]methyl}-4-methylphenyl-6-(hydroxymethyl-3,4,5,6-tetrahydro-2H-pyran-3,4,5-triol hemihydrate]. The dihedral angles between the methylbenzene and thiophene rings are 115.7 (4 and 111.7 (4°, while the dihedral angles between the fluorobenzene and thiophene rings are 24.2 (6 and 20.5 (9° in molecules A and B, respectively. The hydropyran ring exhibits a chair conformation in both canagliflozin molecules. In the crystal, the canagliflozin molecules and lattice water molecules are connected via O—H...O hydrogen bonds into a three-dimensional supramolecular architecture.

  8. Crystal Structure of 8-Demethoxyrunanine

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Ling

    2008-01-01

    A new hasubanane-type alkaloid, 8-demethoxyrunanine, was isolated from Sino- menium acutum and characterized by melting point, HREIMS, 1H NMR, and X-ray diffraction analysis. X-ray diffraction reveals that the title compound crystallizes in the orthorhombic system, space group P212121 with a = 7.308(1), b = 21.742(5), c = 22.893(4) ?, V = 3637.5(11) ?3, Z = 8, Dx = 1.254 g/cm3, F(000) = 1472, μ(MoKα) = 0.087 mm-1, the final R = 0.0438 and wR = 0.0575 for 4497 independent reflections with Rint = 0.0192 and 2091 observed reflections with I > 2σ(I). Four rings (ring A: one benzene ring, ring B: one hexagon carbon ring in a half-chair conformation, ring C: one hexagon carbon ring with α,β-unsaturated ketone segment (-CR2=CR1-C=O) in a screw-boat conformation, and ring D: one nonplanar tetrahydropyrrole) form a hasubanane-type alkaloid.

  9. Crystal structure determination of Jatrorrhizine chloride

    Institute of Scientific and Technical Information of China (English)

    LEI XianRong; YANG JianHua; LIN Xiang; DAI Qin; CHENG Qiang; GUO LingHong; LI Hui

    2009-01-01

    Optimum resolution data of powder X-ray diffraction (PXRD) for Jatrorrhizine (Jat) were collected by an X' Pert Pro MPD diffractometer with an X'celerator detector under the stepwise scanning condition as 8.255 ms and 0.00836°per step,2θrange of 50°-80° and total scanning period of 8-10 min. Indexing of the crystal system and a search of the space group from the powder X-ray diffraction data were conducted by the computational crystallography method. The pilot crystal models of Jat were globally optimized with Monte Carlo method and then refined with the Rietveld method. In parallel with PXRD test,single crystals of Jat were cultured in an aqueous solution by a slow-decreasing temperature method,then its crystal structure was determined by single crystal X-ray diffraction (SCXRD). Both crystal structures from PXRD and SCXRD are identical. The results show that the crystal structure of Jat belongs to a monoclinic system and the space group P21/c. The parameters of cell dimensions from PXRD are a=7.69(A),b= 12.55(A),c=20.89(A),β=106.53°,Z=4,and V=1933.4(A)3,meanwhile the parameters from SCXRD are a=7.72(A),b=12.61(A),c=20.99(A),β=106.38°,Z=4,and V=1961.3(A)3.

  10. Crystal structure of the eukaryotic ribosome.

    Science.gov (United States)

    Ben-Shem, Adam; Jenner, Lasse; Yusupova, Gulnara; Yusupov, Marat

    2010-11-26

    Crystal structures of prokaryotic ribosomes have described in detail the universally conserved core of the translation mechanism. However, many facets of the translation process in eukaryotes are not shared with prokaryotes. The crystal structure of the yeast 80S ribosome determined at 4.15 angstrom resolution reveals the higher complexity of eukaryotic ribosomes, which are 40% larger than their bacterial counterparts. Our model shows how eukaryote-specific elements considerably expand the network of interactions within the ribosome and provides insights into eukaryote-specific features of protein synthesis. Our crystals capture the ribosome in the ratcheted state, which is essential for translocation of mRNA and transfer RNA (tRNA), and in which the small ribosomal subunit has rotated with respect to the large subunit. We describe the conformational changes in both ribosomal subunits that are involved in ratcheting and their implications in coordination between the two associated subunits and in mRNA and tRNA translocation.

  11. Modular crystals as modulated structures

    DEFF Research Database (Denmark)

    Elcoro, L.; Perez-Mato, J.M.; Friese, K.;

    2008-01-01

    The use of the superspace formalism is extended to the description and refinement of the homologous series of modular structures with two symmetry-related modules with different orientations. The lillianite homologous series has been taken as a study case. Starting from a commensurate modulated c...

  12. Shear induced structures in crystallizing cocoa butter

    Science.gov (United States)

    Mazzanti, Gianfranco; Guthrie, Sarah E.; Sirota, Eric B.; Marangoni, Alejandro G.; Idziak, Stefan H. J.

    2004-03-01

    Cocoa butter is the main structural component of chocolate and many cosmetics. It crystallizes in several polymorphs, called phases I to VI. We used Synchrotron X-ray diffraction to study the effect of shear on its crystallization. A previously unreported phase (phase X) was found and a crystallization path through phase IV under shear was observed. Samples were crystallized under shear from the melt in temperature controlled Couette cells, at final crystallization temperatures of 17.5^oC, 20^oC and 22.5^oC in Beamline X10A of NSLS. The formation of phase X was observed at low shear rates (90 s-1) and low crystallization temperature (17.5^oC), but was absent at high shear (720 s-1) and high temperature (20^oC). The d-spacing and melting point suggest that this new phase is a mixture rich on two of the three major components of cocoa butter. We also found that, contrary to previous reports, the transition from phase II to phase V can happen through the intermediate phase IV, at high shear rates and temperature.

  13. Structure analysis on synthetic emerald crystals

    Science.gov (United States)

    Lee, Pei-Lun; Lee, Jiann-Shing; Huang, Eugene; Liao, Ju-Hsiou

    2013-05-01

    Single crystals of emerald synthesized by means of the flux method were adopted for crystallographic analyses. Emerald crystals with a wide range of Cr3+-doping content up to 3.16 wt% Cr2O3 were examined by X-ray single crystal diffraction refinement method. The crystal structures of the emerald crystals were refined to R 1 (all data) of 0.019-0.024 and w R 2 (all data) of 0.061-0.073. When Cr3+ substitutes for Al3+, the main adjustment takes place in the Al-octahedron and Be-tetrahedron. The effect of substitution of Cr3+ for Al3+ in the beryl structure results in progressively lengthening of the Al-O distance, while the length of the other bonds remains nearly unchanged. The substitution of Cr3+ for Al3+ may have caused the expansion of a axis, while keeping the c axis unchanged in the emerald lattice. As a consequence, the Al-O-Si and Al-O-Be bonding angles are found to decrease, while the angle of Si-O-Be increases as the Al-O distance increases during the Cr replacement.

  14. Troublesome Crystal Structures: Prevention, Detection, and Resolution.

    Science.gov (United States)

    Harlow, Richard L

    1996-01-01

    A large number of incorrect crystal structures is being published today. These structures are proving to be a particular problem to those of us who are interested in comparing structural moieties found in the databases in order to develop structure-property relationships. Problems can reside in the input data, e.g., wrong unit cell or low quality intensity data, or in the structural model, e.g., wrong space group or atom types. Many of the common mistakes are, however, relatively easy to detect and thus should be preventable; at the very least, suspicious structures can be flagged, if not by the authors then by the referees and, ultimately, the crystallographic databases. This article describes some of the more common mistakes and their effects on the resulting structures, lists a series of tests that can be used to detect incorrect structures, and makes a strong plea for the publication of higher quality structures.

  15. Determining crystal structures through crowdsourcing and coursework

    OpenAIRE

    2016-01-01

    We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit pla...

  16. Determining crystal structures through crowdsourcing and coursework

    OpenAIRE

    Horowitz, Scott; Koepnick, Brian; Jain, Neha; Pikkanen, Petri; Shehzad, Raafay; Viosca, Randy; James Fraser, Robert; Leduc, Robert; Madala, Roman; Shnider, Scott; de Boisblanc, Sharon; Butkovich, Slava; Bliven, Spencer; Koldewey, Philipp; Hettler, Stephen

    2016-01-01

    We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit pla...

  17. Crystal Structure of Human Enterovirus 71

    Energy Technology Data Exchange (ETDEWEB)

    Plevka, Pavel; Perera, Rushika; Cardosa, Jane; Kuhn, Richard J.; Rossmann, Michael G. (Purdue); (Sentinext)

    2013-04-08

    Enterovirus 71 is a picornavirus associated with fatal neurological illness in infants and young children. Here, we report the crystal structure of enterovirus 71 and show that, unlike in other enteroviruses, the 'pocket factor,' a small molecule that stabilizes the virus, is partly exposed on the floor of the 'canyon.' Thus, the structure of antiviral compounds may require a hydrophilic head group designed to interact with residues at the entrance of the pocket.

  18. Crystal structure of racemic [(1R,2S,3R,4S,6S)-2,6-bis-(furan-2-yl)-4-hy-droxy-4-(thio-phen-2-yl)cyclo-hexane-1,3-di-yl]bis-(thio-phen-2-yl-methanone).

    Science.gov (United States)

    Çelik, Ísmail; Ersanlı, Cem Cüneyt; Akkurt, Mehmet; Gezegen, Hayrettin; Köseoğlu, Rahmi

    2016-07-01

    In the title compound, C28H22O5S3, the central cyclo-hexane ring adopts a chair conformation. The atoms of the furan ring attached to the 6-position of the central cyclo-hexane ring are disordered over two sets of sites with occupancies of 0.832 (5) and 0.168 (5). The hy-droxy group is disordered over two positions (at the 4- and 6-positions of the cyclo-hexane ring) in the ratio 0.832 (5):0.168 (5). In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming layers parallel to (100).

  19. THE CRYSTAL STRUCTURE OF 2,7-DIACETOXYTRANS-15,16-DIMETHYL-15,16-DIHYDROPYRENE,

    Science.gov (United States)

    AROMATIC COMPOUNDS, CRYSTAL STRUCTURE ), (*POLYCYCLIC COMPOUNDS, CRYSTAL STRUCTURE ), (* CRYSTAL STRUCTURE , POLYCYCLIC COMPOUNDS), ESTERS, MOLECULAR STRUCTURE, CHEMICAL BONDS, X RAY DIFFRACTION, SCINTILLATION COUNTERS, CANADA

  20. Photonic Crystal Laser-Driven Accelerator Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, Benjamin M.

    2007-08-22

    Laser-driven acceleration holds great promise for significantly improving accelerating gradient. However, scaling the conventional process of structure-based acceleration in vacuum down to optical wavelengths requires a substantially different kind of structure. We require an optical waveguide that (1) is constructed out of dielectric materials, (2) has transverse size on the order of a wavelength, and (3) supports a mode with speed-of-light phase velocity in vacuum. Photonic crystals---structures whose electromagnetic properties are spatially periodic---can meet these requirements. We discuss simulated photonic crystal accelerator structures and describe their properties. We begin with a class of two-dimensional structures which serves to illustrate the design considerations and trade-offs involved. We then present a three-dimensional structure, and describe its performance in terms of accelerating gradient and efficiency. We discuss particle beam dynamics in this structure, demonstrating a method for keeping a beam confined to the waveguide. We also discuss material and fabrication considerations. Since accelerating gradient is limited by optical damage to the structure, the damage threshold of the dielectric is a critical parameter. We experimentally measure the damage threshold of silicon for picosecond pulses in the infrared, and determine that our structure is capable of sustaining an accelerating gradient of 300 MV/m at 1550 nm. Finally, we discuss possibilities for manufacturing these structures using common microfabrication techniques.

  1. Crystal structure of [1,1':3',1''-ter-phenyl]-2',3,3''-tri-carb-oxy-lic acid.

    Science.gov (United States)

    Decato, Daniel A; Berryman, Orion B

    2015-09-01

    The asymmetric unit of the title compound, C21H14O6, com-prises two symmetrically independent mol-ecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carb-oxy-lic acid groups rotated by 15.8 (1) and 17.5 (1)° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being inter-connected by hydrogen bonds involving the remaining carb-oxy-lic acid groups. The plane of the central carb-oxy-lic acid group forms dihedral angles of 62.5 (1) and 63.0 (1)° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it inter-connects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The 'distal' carb-oxy-lic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1) and 7.1 (1)°. These groups also form intra- and inter-layer hydrogen bonds, but with 'reversed' functionality, as compared with the central carb-oxy-lic acid groups.

  2. Crystal structure of 3-(thio-phen-2-yl)-5-p-tolyl-4,5-di-hydro-1H-pyrazole-1-carbo-thio-amide.

    Science.gov (United States)

    Naveen, S; Pavithra, G; Abdoh, Muneer; Ajay Kumar, K; Warad, Ismail; Lokanath, N K

    2015-07-01

    In the title compound, C15H15N3S2, the central pyrazole ring adopts a twisted conformation on the -CH-CH2- bond. Its mean plane makes dihedral angles of 7.19 (12) and 71.13 (11)° with those of the thio-phene and toluene rings, respectively. The carbothi-amide group [C(=S)-N] is inclined to the pyrazole ring mean plane by 16.8 (2)°. In the crystal, mol-ecules are linked by N-H⋯S hydrogen bonds, forming chains propagating along [010]. Within the chains, there are N-H⋯π inter-actions present. Between the chains there are weak parallel slipped π-π inter-actions involving inversion-related thio-phene and pyrazole rings [inter-centroid distance = 3.7516 (14) Å; inter-planar distance = 3.5987 (10) Å; slippage = 1.06 Å].

  3. Synthesis and Crystal Structure of Dehydroandrographolide Dipolycyclophosphate

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The title compound was synthesized and characterized by IR, NMR, H R S I-M S and MS, and its crystal structure was determined by single-crystal X-ray diffraction. The crystal is of orthorhombic system (C4oH52O11P2, Mr= 770.76), space group P21212, with a = 22.562(5), b =29.224(6), c = 7.1953(14) A, V = 4744.2(16) A3, Z = 4, Dc = 1.079 g/cm3, F(000) = 1640 andμ =0.141 mm-1. The final R = 0.0758 and wR = 0.1778 for 2794 observed reflections with I > 2o(I).Intermolecular hydrogen bonds are found between the O atom of carbonyl group and H atoms of olefinic carbon. The absolute configuration of this molecule was confirmed by comparison with that of the original material.

  4. Crystal structure of N-(4-hydroxybenzylacetone thiosemicarbazone

    Directory of Open Access Journals (Sweden)

    Saray Argibay-Otero

    2017-09-01

    Full Text Available The structure of the title compound, C11H15N3OS, shows the flexibility due to the methylene group at the thioamide N atom in the side chain, resulting in the molecule being non-planar. The dihedral angle between the plane of the benzene ring and that defined by the atoms of the thiosemicarbazide arm is 79.847 (4°. In the crystal, the donor–acceptor hydrogen-bond character of the –OH group dominates the intermolecular associations, acting as a donor in an O—H...S hydrogen bond, as well as being a double acceptor in a centrosymmetric cyclic bridging N—H...O,O′ interaction [graph set R22(4]. The result is a one-dimensional duplex chain structure, extending along [111]. The usual N—H...S hydrogen-bonding association common in thiosemicarbazone crystal structures is not observed.

  5. Crystal structure of low-symmetry rondorfite

    Science.gov (United States)

    Rastsvetaeva, R. K.; Zadov, A. E.; Chukanov, N. V.

    2008-03-01

    The crystal structure of an aluminum-rich variety of the mineral rondorfite with the composition Ca16[Mg2(Si7Al)(O31OH)]Cl4 from the skarns of the Verkhne-Chegemskoe plateau (the Kabardino-Balkarian Republic, the Northern Caucasus Region, Russia) was solved in the triclinic space group with the unit-cell parameters a = 15.100(2) Å, b = 15.110(2) Å, c = 15.092(2) Å, α = 90.06(1)°, β = 90.01(1)°, γ = 89.93(1)°, Z = 4, sp. gr. P1. The structural model consisting of 248 independent atoms was determined by the phase-correction method and refined to R = 3.8% with anisotropic displacement parameters based on all 7156 independent reflections with 7156 F > 3σ( F). The crystal structure is based on pentamers consisting of four Si tetrahedra linked by the central Mg tetrahedron. The structure can formally be refined in the cubic space group ( a = 15.105 Å, sp. gr. Fd overline 3 , seven independent positions) with anisotropic displacement parameters to R = 2.74% based on 579 reflections with F > 3σ( F) without accounting for more than 1000 observed reflections, which are inconsistent with the cubic symmetry of the crystal structure.

  6. Structure sensitive properties of KTP-type crystals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Adding various dopants during the growth of the parent KTiOPO4 (KTP) crystal has given rise to an extensive series of KTP-type crystals. The doped KTP or KTP-type crystals often have very subtle structural variations from pure KTP crystals. As a result of these structural changes the KTP-type crystals often exhibit different physical properties, which may be referred to as structure sensitive properties. It is possible to fine-tune the nonlinear optical properties of KTP crystals through doping. This results in a broad range of applications for KTP-type crystals.

  7. Lessons from crystal structures of kainate receptors

    DEFF Research Database (Denmark)

    Møllerud, Stine; Frydenvang, Karla Andrea; Pickering, Darryl S;

    2017-01-01

    synaptic transmission and modulate network excitability by regulating neurotransmitter release. Dysfunction of kainate receptors has been implicated in several neurological disorders such as epilepsy, schizophrenia and depression. Here we provide a review on the current understanding of kainate receptor...... structure and how they bind agonists, antagonists and ions. The first structure of the ligand-binding domain of the GluK1 subunit was reported in 2005, seven years after publication of the crystal structure of a soluble construct of the ligand-binding domain of the AMPA-type subunit GluA2. Today, a full...

  8. Crystal structure of tris(hydroxylammonium orthophosphate

    Directory of Open Access Journals (Sweden)

    Malte Leinemann

    2015-11-01

    Full Text Available The crystal structure of the title salt, ([H3NOH]+3·[PO4]3−, consists of discrete hydroxylammonium cations and orthophosphate anions. The atoms of the cation occupy general positions, whereas the anion is located on a threefold rotation axis that runs through the phosphorus atom and one of the phosphate O atoms. In the crystal structure, cations and anions are linked by intermolecular O—H...O and N—H...O hydrogen bonds into a three-dimensional network. Altogether, one very strong O—H...O, two N—H...O hydrogen bonds of medium strength and two weaker bifurcated N—H...O interactions are observed.

  9. Crystal Structures of New Ammonium 5-Aminotetrazolates

    Directory of Open Access Journals (Sweden)

    Martin Lampl

    2014-11-01

    Full Text Available The crystal structures of three salts of anionic 5-aminotetrazole are described. The tetramethylammonium salt (P forms hydrogen-bonded ribbons of anions which accept weak C–H···N contacts from the cations. The cystamine salt (C2/c shows wave-shaped ribbons of anions linked by hydrogen bonds to screw-shaped dications. The tetramethylguanidine salt (P21/c exhibits layers of anions hydrogen-bonded to the cations.

  10. Crystal Structure of a New Cembranolide Diterpene

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new cembranoide deterpene was isolated from the soft coral Sinularia Tenella. The crystal and chemical structure of the title compound were determined by means of spectroscopic methods and X-ray diffraction analysis as (1R* , 4R* , 5S* , 12S* , 12R* )-9-acetoxy-cembr-8E, 15 (17)-dien-16,4-olide. It shows a moderate cytotoxicity against P 388 and L 1210 cell lines.

  11. Crystal structure of an archaeal actin homolog.

    Science.gov (United States)

    Roeben, Annette; Kofler, Christine; Nagy, István; Nickell, Stephan; Hartl, F Ulrich; Bracher, Andreas

    2006-04-21

    Prokaryotic homologs of the eukaryotic structural protein actin, such as MreB and ParM, have been implicated in determination of bacterial cell shape, and in the segregation of genomic and plasmid DNA. In contrast to these bacterial actin homologs, little is known about the archaeal counterparts. As a first step, we expressed a predicted actin homolog of the thermophilic archaeon Thermoplasma acidophilum, Ta0583, and determined its crystal structure at 2.1A resolution. Ta0583 is expressed as a soluble protein in T.acidophilum and is an active ATPase at physiological temperature. In vitro, Ta0583 forms sheets with spacings resembling the crystal lattice, indicating an inherent propensity to form filamentous structures. The fold of Ta0583 contains the core structure of actin and clearly belongs to the actin/Hsp70 superfamily of ATPases. Ta0583 is approximately equidistant from actin and MreB on the structural level, and combines features from both eubacterial actin homologs, MreB and ParM. The structure of Ta0583 co-crystallized with ADP indicates that the nucleotide binds at the interface between the subdomains of Ta0583 in a manner similar to that of actin. However, the conformation of the nucleotide observed in complex with Ta0583 clearly differs from that in complex with actin, but closely resembles the conformation of ParM-bound nucleotide. On the basis of sequence and structural homology, we suggest that Ta0583 derives from a ParM-like actin homolog that was once encoded by a plasmid and was transferred into a common ancestor of Thermoplasma and Ferroplasma. Intriguingly, both genera are characterized by the lack of a cell wall, and therefore Ta0583 could have a function in cellular organization.

  12. Crystal Structure Refinement of Synthetic Pure Gyrolite

    Directory of Open Access Journals (Sweden)

    Arūnas Baltušnikas

    2015-03-01

    Full Text Available Pure calcium silicate hydrate – gyrolite was prepared under the saturated steam pressure at 473 K temperature in rotating autoclave. The crystal structure of synthetic gyrolite was investigated by X-ray diffraction and refined using Le Bail, Rietveld and crystal structure modelling methods. Background, peak shape parameters and verification of the space group were performed by the Le Bail full pattern decomposition. Peculiarities of interlayer sheet X of gyrolite unit cell were highlighted by Rietveld refinement. Possible atomic arrangement in interlayer sheet X was solved by global optimization method. Most likelihood crystal structure model of gyrolite was calculated by final Rietveld refinement. It was crystallographically showed, that cell parameters are: a = 0.9713(2 nm, b = 0.9715(2 nm, c = 2.2442(3 nm and alfa = 95.48(2 º, beta = 91.45(2 °, gamma = l20.05(3 °.DOI: http://dx.doi.org/10.5755/j01.ms.21.1.5460

  13. Lessons from crystal structures of kainate receptors.

    Science.gov (United States)

    Møllerud, Stine; Frydenvang, Karla; Pickering, Darryl S; Kastrup, Jette Sandholm

    2017-01-01

    Kainate receptors belong to the family of ionotropic glutamate receptors. These receptors assemble from five subunits (GluK1-5) into tetrameric ion channels. Kainate receptors are located at both pre- and postsynaptic membranes in the central nervous system where they contribute to excitatory synaptic transmission and modulate network excitability by regulating neurotransmitter release. Dysfunction of kainate receptors has been implicated in several neurological disorders such as epilepsy, schizophrenia and depression. Here we provide a review on the current understanding of kainate receptor structure and how they bind agonists, antagonists and ions. The first structure of the ligand-binding domain of the GluK1 subunit was reported in 2005, seven years after publication of the crystal structure of a soluble construct of the ligand-binding domain of the AMPA-type subunit GluA2. Today, a full-length structure has been determined of GluK2 by cryo electron microscopy to 7.6 Å resolution as well as 84 high-resolution crystal structures of N-terminal domains and ligand-binding domains, including agonist and antagonist bound structures, modulatory ions and mutations. However, there are still many unanswered questions and challenges in front of us. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.

  14. A DIRECT DETERMINATION OF THE CRYSTAL STRUCTURE OF 2,3,4,6-TETRANITROANILINE,

    Science.gov (United States)

    ORGANIC NITROGEN COMPOUNDS, CRYSTAL STRUCTURE ), (* CRYSTAL STRUCTURE , EXPLOSIVES), (*EXPLOSIVES, CRYSTAL STRUCTURE ), AROMATIC COMPOUNDS, AMINES, NITRATES, LEAST SQUARES METHOD, FOURIER ANALYSIS, CHEMICAL BONDS.

  15. Methyl-phospho-nic acid, CH3PO(OH)2.

    Science.gov (United States)

    Reuter, Hans; Reichelt, Martin

    2014-03-01

    The asymmetric unit of the title compound, CH5O3P, contains two independent mol-ecules with nearly identical bond lengths and angles. In the crystal, each of the mol-ecules acts as acceptor (P=O) and donor (P-OH) of four hydrogen bonds to three adjacent mol-ecules, resulting in the formation of two different bilayers (one for each mol-ecule) stacked perpendicular to the a axis in the crystal.

  16. Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.

    Science.gov (United States)

    Chesick, John P.

    1989-01-01

    Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)

  17. Relative substituent orientation in the structure of cis-3-chloro-1,3-dimethyl-N-(4-nitro-phen-yl)-2-oxo-cyclo-pentane-1-carboxamide.

    Science.gov (United States)

    Zeller, Matthias; Warneke, Jonas; Azov, Vladimir

    2014-09-01

    The structure of the title compound, C14H15ClN2O4, prepared by reaction of a methacryloyl dimer with nitro-aniline, was determined to establish the relative substituent orientation on the cyclo-penta-none ring. In agreement with an earlier proposed reaction mechanism, the amide group and the methyl group adjacent to the chloro substituent adopt equatorial positions and relative cis orientation, whereas the Cl substituent itself and the methyl group adjacent to the amide have axial orientations relative to the mean plane of the five-membered ring. The conformation of the mol-ecule is stabilized by one classical N-H⋯O (2.18 Å) and one non-classical C-H⋯O (2.23 Å) hydrogen bond, each possessing an S(6) graph-set motif. The crystal packing is defined by several non-classical intra-molecular hydrogen bonds, as well as by partial stacking of the aromatic rings.

  18. THE CRYSTAL STRUCTURE OF 2-(4’-AMINO-5’AMINO PYRIMIDY) -2-PENTENE-4-ONE.

    Science.gov (United States)

    NITROGEN HETEROCYCLIC COMPOUNDS, CRYSTAL STRUCTURE ), (*AMINES, CRYSTAL STRUCTURE ), (*KETONES, CRYSTAL STRUCTURE ), CRYSTAL LATTICES, FOURIER ANALYSIS, LEAST SQUARES METHOD, MOLECULAR STRUCTURE, PYRIMIDINES, CHEMICAL BONDS

  19. Crystal structure of natural phaeosphaeride A

    Directory of Open Access Journals (Sweden)

    Victoria V. Abzianidze

    2015-08-01

    Full Text Available The asymmetric unit of the title compound, C15H23NO5, contains two independent molecules. Phaeosphaeride A contains two primary sections, an alkyl chain consisting of five C atoms and a cyclic system consisting of fused five- and six-membered rings with attached substituents. In the crystal, the molecules form layered structures. Nearly planar sheets, parallel to the (001 plane, form bilayers of two-dimensional hydrogen-bonded networks with the hydroxy groups located on the interior of the bilayer sheets. The network is constructed primarily of four O—H...O hydrogen bonds, which form a zigzag pattern in the (001 plane. The butyl chains interdigitate with the butyl chains on adjacent sheets. The crystal was twinned by a twofold rotation about the c axis, with refined major–minor occupancy fractions of 0.718 (6:0.282 (6.

  20. Determining crystal structures through crowdsourcing and coursework

    Science.gov (United States)

    Horowitz, Scott; Koepnick, Brian; Martin, Raoul; Tymieniecki, Agnes; Winburn, Amanda A.; Cooper, Seth; Flatten, Jeff; Rogawski, David S.; Koropatkin, Nicole M.; Hailu, Tsinatkeab T.; Jain, Neha; Koldewey, Philipp; Ahlstrom, Logan S.; Chapman, Matthew R.; Sikkema, Andrew P.; Skiba, Meredith A.; Maloney, Finn P.; Beinlich, Felix R. M.; Caglar, Ahmet; Coral, Alan; Jensen, Alice Elizabeth; Lubow, Allen; Boitano, Amanda; Lisle, Amy Elizabeth; Maxwell, Andrew T.; Failer, Barb; Kaszubowski, Bartosz; Hrytsiv, Bohdan; Vincenzo, Brancaccio; de Melo Cruz, Breno Renan; McManus, Brian Joseph; Kestemont, Bruno; Vardeman, Carl; Comisky, Casey; Neilson, Catherine; Landers, Catherine R.; Ince, Christopher; Buske, Daniel Jon; Totonjian, Daniel; Copeland, David Marshall; Murray, David; Jagieła, Dawid; Janz, Dietmar; Wheeler, Douglas C.; Cali, Elie; Croze, Emmanuel; Rezae, Farah; Martin, Floyd Orville; Beecher, Gil; de Jong, Guido Alexander; Ykman, Guy; Feldmann, Harald; Chan, Hugo Paul Perez; Kovanecz, Istvan; Vasilchenko, Ivan; Connellan, James C.; Borman, Jami Lynne; Norrgard, Jane; Kanfer, Jebbie; Canfield, Jeffrey M.; Slone, Jesse David; Oh, Jimmy; Mitchell, Joanne; Bishop, John; Kroeger, John Douglas; Schinkler, Jonas; McLaughlin, Joseph; Brownlee, June M.; Bell, Justin; Fellbaum, Karl Willem; Harper, Kathleen; Abbey, Kirk J.; Isaksson, Lennart E.; Wei, Linda; Cummins, Lisa N.; Miller, Lori Anne; Bain, Lyn; Carpenter, Lynn; Desnouck, Maarten; Sharma, Manasa G.; Belcastro, Marcus; Szew, Martin; Szew, Martin; Britton, Matthew; Gaebel, Matthias; Power, Max; Cassidy, Michael; Pfützenreuter, Michael; Minett, Michele; Wesselingh, Michiel; Yi, Minjune; Cameron, Neil Haydn Tormey; Bolibruch, Nicholas I.; Benevides, Noah; Kathleen Kerr, Norah; Barlow, Nova; Crevits, Nykole Krystyne; Dunn, Paul; Silveira Belo Nascimento Roque, Paulo Sergio; Riber, Peter; Pikkanen, Petri; Shehzad, Raafay; Viosca, Randy; James Fraser, Robert; Leduc, Robert; Madala, Roman; Shnider, Scott; de Boisblanc, Sharon; Butkovich, Slava; Bliven, Spencer; Hettler, Stephen; Telehany, Stephen; Schwegmann, Steven A.; Parkes, Steven; Kleinfelter, Susan C.; Michael Holst, Sven; van der Laan, T. J. A.; Bausewein, Thomas; Simon, Vera; Pulley, Warwick; Hull, William; Kim, Annes Yukyung; Lawton, Alexis; Ruesch, Amanda; Sundar, Anjali; Lawrence, Anna-Lisa; Afrin, Antara; Maheshwer, Bhargavi; Turfe, Bilal; Huebner, Christian; Killeen, Courtney Elizabeth; Antebi-Lerrman, Dalia; Luan, Danny; Wolfe, Derek; Pham, Duc; Michewicz, Elaina; Hull, Elizabeth; Pardington, Emily; Galal, Galal Osama; Sun, Grace; Chen, Grace; Anderson, Halie E.; Chang, Jane; Hewlett, Jeffrey Thomas; Sterbenz, Jennifer; Lim, Jiho; Morof, Joshua; Lee, Junho; Inn, Juyoung Samuel; Hahm, Kaitlin; Roth, Kaitlin; Nair, Karun; Markin, Katherine; Schramm, Katie; Toni Eid, Kevin; Gam, Kristina; Murphy, Lisha; Yuan, Lucy; Kana, Lulia; Daboul, Lynn; Shammas, Mario Karam; Chason, Max; Sinan, Moaz; Andrew Tooley, Nicholas; Korakavi, Nisha; Comer, Patrick; Magur, Pragya; Savliwala, Quresh; Davison, Reid Michael; Sankaran, Roshun Rajiv; Lewe, Sam; Tamkus, Saule; Chen, Shirley; Harvey, Sho; Hwang, Sin Ye; Vatsia, Sohrab; Withrow, Stefan; Luther, Tahra K.; Manett, Taylor; Johnson, Thomas James; Ryan Brash, Timothy; Kuhlman, Wyatt; Park, Yeonjung; Popović, Zoran; Baker, David; Khatib, Firas; Bardwell, James C. A.

    2016-09-01

    We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality.

  1. Synthesis and structural characterization of a single-crystal to single-crystal transformable coordination polymer.

    Science.gov (United States)

    Tian, Yuyang; Allan, Phoebe K; Renouf, Catherine L; He, Xiang; McCormick, Laura J; Morris, Russell E

    2014-01-28

    A single-crystal to single-crystal transformable coordination polymer compound was hydrothermally synthesized. The structural rearrangement is induced by selecting a ligand that contains both strong and weaker coordinating groups. Both hydrated and dehydrated structures were determined by single crystal X-ray analysis.

  2. Crystal structure of Cryptosporidium parvum pyruvate kinase.

    Directory of Open Access Journals (Sweden)

    William J Cook

    Full Text Available Pyruvate kinase plays a critical role in cellular metabolism of glucose by serving as a major regulator of glycolysis. This tetrameric enzyme is allosterically regulated by different effector molecules, mainly phosphosugars. In response to binding of effector molecules and substrates, significant structural changes have been identified in various pyruvate kinase structures. Pyruvate kinase of Cryptosporidium parvum is exceptional among known enzymes of protozoan origin in that it exhibits no allosteric property in the presence of commonly known effector molecules. The crystal structure of pyruvate kinase from C. parvum has been solved by molecular replacement techniques and refined to 2.5 Å resolution. In the active site a glycerol molecule is located near the γ-phosphate site of ATP, and the protein structure displays a partially closed active site. However, unlike other structures where the active site is closed, the α6' helix in C. parvum pyruvate kinase unwinds and assumes an extended conformation. In the crystal structure a sulfate ion is found at a site that is occupied by a phosphate of the effector molecule in many pyruvate kinase structures. A new feature of the C. parvum pyruvate kinase structure is the presence of a disulfide bond cross-linking the two monomers in the asymmetric unit. The disulfide bond is formed between cysteine residue 26 in the short N-helix of one monomer with cysteine residue 312 in a long helix (residues 303-320 of the second monomer at the interface of these monomers. Both cysteine residues are unique to C. parvum, and the disulfide bond remained intact in a reduced environment. However, the significance of this bond, if any, remains unknown at this time.

  3. Diterbium heptanickel: a crystal structure redetermination

    Directory of Open Access Journals (Sweden)

    Volodymyr Levytskyy

    2014-08-01

    Full Text Available The crystal structure of the title compound, Tb2Ni7, was redetermined from single-crystal X-ray diffraction data. In comparison with previous studies based on powder X-ray diffraction data [Lemaire et al. (1967. C. R. Acad. Sci. Ser. B, 265, 1280–1282; Lemaire & Paccard (1969. Bull. Soc. Fr. Mineral. Cristallogr. 92, 9–16; Buschow & van der Goot (1970. J. Less-Common Met. 22, 419–428], the present redetermination affords refined coordinates and anisotropic displacement parameters for all atoms. A partial occupation for one Tb atom results in the non-stoichiometric composition Tb1.962 (4Ni7. The title compound adopts the Ce2Ni7 structure type and can also be derived from the CaCu5 structure type as an intergrowth structure. The asymmetric unit contains two Tb sites (both site symmetries 3m. and five Ni sites (.m., mm2, 3m., 3m., -3m.. The two different coordination polyhedra of Tb are a Frank–Kasper polyhedron formed by four Tb and 12 Ni atoms and a pseudo Frank–Kasper polyhedron formed by two Tb and 18 Ni atoms. The four different coordination polyhedra of Ni are Frank–Kasper icosahedra formed by five Tb and seven Ni atoms, four Tb and eight Ni atoms, three Tb and nine Ni atoms, and six Tb and six Ni atoms, respectively.

  4. Crystal structure prediction from first principles: The crystal structures of glycine

    Science.gov (United States)

    Lund, Albert M.; Pagola, Gabriel I.; Orendt, Anita M.; Ferraro, Marta B.; Facelli, Julio C.

    2015-04-01

    Here we present the results of our unbiased searches of glycine polymorphs obtained using the genetic algorithms search implemented in MGAC, modified genetic algorithm for crystals, coupled with the local optimization and energy evaluation provided by Quantum Espresso. We demonstrate that it is possible to predict the crystal structures of a biomedical molecule using solely first principles calculations. We were able to find all the ambient pressure stable glycine polymorphs, which are found in the same energetic ordering as observed experimentally and the agreement between the experimental and predicted structures is of such accuracy that the two are visually almost indistinguishable.

  5. Tailoring quantum structures for active photonic crystals

    DEFF Research Database (Denmark)

    Kuznetsova, Nadezda

    This work is dedicated to the tailoring of quantum structures, with particular attention to the integration of selective area grown (SAG) active material into photonic crystal (PhC) slabs. The platform based on active PhC is vital to the realization of highly efficient elements with low energy...... consumption for on-chip and chip-to-chip optical communication. In order to develop metal-organic vapor phase epitaxial selective area etching and growth, a mask was fabricated in the HSQ e-beam resist including optimization of exposure and development conditions. By use of CBr4 as an etchant, in situ etching...... area and between the structures oriented along the [0-1-1] and [0-11] directions. Strong wavelength dependence with variations of the mask width of a few μm and opening sizes of hundreds of nanometers was observed. Incorporation of an active medium into PhC structures has showed promising results...

  6. Isolation and Crystal Structure of Horminone

    Institute of Scientific and Technical Information of China (English)

    陈晓; 廖仁安; 翁林红; 谢庆兰; 邓锋杰

    2000-01-01

    The horminone (C20H28O4, Mr= 332.85) was first isolated from the leaves of Rabdosia Serra (Maxim) Hara and its crystal structure was determined by X-ray diffraction method. Horminone is orthorhombic with space group P21P21P21, a=7.7186(7), b=9.5506(9), c=24.227(2) A, V=1785.9(3) A3, Z=4, Dc=1.236g/cm3, λ=0. 71073 A , μ(MoKα)=0. 085mm-1, F(000)=720. The structure was refined to R=0. 0369, wR=0.0978 for 2446 reflections with I>2σ(Ⅰ). X-ray diffraction analysis reveals that there are three six-membered rings in the title molecule. Ring A is in the chair conformation, ring C has the structure of quinone and there are two intermolecular hydrogen bonds between two molecules.

  7. Crystal structure of (ferrocenylmethyldimethylammonium hydrogen oxalate

    Directory of Open Access Journals (Sweden)

    Mamadou Ndiaye

    2015-08-01

    Full Text Available The crystal structure of the title salt, [Fe(C5H5(C8H13N](HC2O4, consists of discrete (ferrocenylmethyldimethylammonium cations and hydrogen oxalate anions. The anions are connected through a strong O—H...O hydrogen bond, forming linear chains running parallel to [100]. The cations are linked to the anions through bifurcated N—H...(O,O′ hydrogen bonds. Weak C—H...π interactions between neighbouring ferrocenyl moieties are also observed.

  8. [Crystal and molecular structure of cytisine salts].

    Science.gov (United States)

    Niedźwiecka, Julia; Przybył, Anna K; Kubicki, Maciej

    2012-01-01

    Cytisine is an alkaloid of plant origin. It is a toxic substance, obtained on an industrial scale from Laburnum anagyroides also known as common laburnum. Today is used in the preparation of anti-smoking products as an agonist of nicotinic receptors nAChR-alpha4beta2. Thanks to crystallographic methods we can examine and describe with high accuracy the actual structure of complex chemical compounds. This work aims to present a series of tests carried out on crystals of cytisine salts, after a prior isolation of cytisine from the seeds of laburnum anagyroides.

  9. Crystal structure of hexaaquadichloridoytterbium(III chloride

    Directory of Open Access Journals (Sweden)

    Kevin M. Knopf

    2015-06-01

    Full Text Available The crystal structure of the title compound, [YbCl2(H2O6]Cl, was determined at 110 K. Samples were obtained from evaporated acetonitrile solutions containing the title compound, which consists of a [YbCl2(H2O6]+ cation and a Cl− anion. The cations in the title compound sit on a twofold axis and form O—H...Cl hydrogen bonds with the nearby Cl− anion. The coordination geometry around the metal centre forms a distorted square antiprism. The ytterbium complex is isotypic with the europium complex [Tambrornino et al. (2014. Acta Cryst. E70, i27].

  10. Crystal Structure of Marburg Virus VP24

    OpenAIRE

    Zhang, Adrianna P. P.; Bornholdt, Zachary A.; Abelson, Dafna M.; Saphire, Erica Ollmann

    2014-01-01

    The VP24 protein plays an essential, albeit poorly understood role in the filovirus life cycle. VP24 is only 30% identical between Marburg virus and the ebolaviruses. Furthermore, VP24 from the ebolaviruses is immunosuppressive, while that of Marburg virus is not. The crystal structure of Marburg virus VP24, presented here, reveals that although the core is similar between the viral genera, Marburg VP24 is distinguished by a projecting β-shelf and an alternate conformation of the N-terminal p...

  11. Crystal structure of Marburg virus VP24.

    Science.gov (United States)

    Zhang, Adrianna P P; Bornholdt, Zachary A; Abelson, Dafna M; Saphire, Erica Ollmann

    2014-05-01

    The VP24 protein plays an essential, albeit poorly understood role in the filovirus life cycle. VP24 is only 30% identical between Marburg virus and the ebolaviruses. Furthermore, VP24 from the ebolaviruses is immunosuppressive, while that of Marburg virus is not. The crystal structure of Marburg virus VP24, presented here, reveals that although the core is similar between the viral genera, Marburg VP24 is distinguished by a projecting β-shelf and an alternate conformation of the N-terminal polypeptide.

  12. Elasticity of some mantle crystal structures. II.

    Science.gov (United States)

    Wang, H.; Simmons, G.

    1973-01-01

    The single-crystal elastic constants are determined as a function of pressure and temperature for rutile structure germanium dioxide (GeO2). The data are qualitatively similar to those of rutile TiO2 measured by Manghnani (1969). The compressibility in the c direction is less than one-half that in the a direction, the pressure derivative of the shear constant is negative, and the pressure derivative of the bulk modulus has a relatively high value of about 6.2. According to an elastic strain energy theory, the negative shear modulus derivative implies that the kinetic barrier to diffusion decreases with increasing pressure.

  13. Crystal structure of a DNA catalyst.

    Science.gov (United States)

    Ponce-Salvatierra, Almudena; Wawrzyniak-Turek, Katarzyna; Steuerwald, Ulrich; Höbartner, Claudia; Pena, Vladimir

    2016-01-14

    Catalysis in biology is restricted to RNA (ribozymes) and protein enzymes, but synthetic biomolecular catalysts can also be made of DNA (deoxyribozymes) or synthetic genetic polymers. In vitro selection from synthetic random DNA libraries identified DNA catalysts for various chemical reactions beyond RNA backbone cleavage. DNA-catalysed reactions include RNA and DNA ligation in various topologies, hydrolytic cleavage and photorepair of DNA, as well as reactions of peptides and small molecules. In spite of comprehensive biochemical studies of DNA catalysts for two decades, fundamental mechanistic understanding of their function is lacking in the absence of three-dimensional models at atomic resolution. Early attempts to solve the crystal structure of an RNA-cleaving deoxyribozyme resulted in a catalytically irrelevant nucleic acid fold. Here we report the crystal structure of the RNA-ligating deoxyribozyme 9DB1 (ref. 14) at 2.8 Å resolution. The structure captures the ligation reaction in the post-catalytic state, revealing a compact folding unit stabilized by numerous tertiary interactions, and an unanticipated organization of the catalytic centre. Structure-guided mutagenesis provided insights into the basis for regioselectivity of the ligation reaction and allowed remarkable manipulation of substrate recognition and reaction rate. Moreover, the structure highlights how the specific properties of deoxyribose are reflected in the backbone conformation of the DNA catalyst, in support of its intricate three-dimensional organization. The structural principles underlying the catalytic ability of DNA elucidate differences and similarities in DNA versus RNA catalysts, which is relevant for comprehending the privileged position of folded RNA in the prebiotic world and in current organisms.

  14. Syntheses and Crystal Structures of Pyrazoline Derivants

    Institute of Scientific and Technical Information of China (English)

    SHI Hai-Bin; JI Shun-Jun; ZHANG Yong

    2005-01-01

    Two pyrazoline derivants 1-(2-benzothiazole)-3-phenyl-5-(3-thiophene)-2- pyrazoline (BPTP) and 1-(2-benzothiazole)-3-(2-thiophene)-5-phenyl-2-pyrazoline (BTPP) have been synthe- sized and their crystal structures were determined by X-ray single-crystal diffraction.Crystal of BPTP belongs to triclinic, space group P with a = 9.4430(11), b = 9.9384(13), c = 9.9394(13) (A), α = 83.107(10), β = 79.947(10), γ = 70.221(7)o, V = 862.42(19) (A)3, Z = 2, Dc = 1.392 g/cm3, μ(MoKα) = 0.316 mm-1, F(000) = 376, λ = 0.71070 (A), (Δρ)max = 0.348, (Δρ)min = -0.481 e/(A)3, the final R = 0.0407 and wR = 0.1055 for 2844 observed reflections with I > 2σ(I).Crystal of BTPP is of monoclinic, space group P21/c with a = 11.6158(17), b = 11.2796(18), c = 13.082(2) (A), α = 90, β = 91.087(4), γ = 90o, V = 1713.7(5) (A)3, Z = 4, Dc = 1.401 g/cm3, μ(MoKα) = 0.318 mm-1, Mr = 361.07, F(000) = 752, λ = 0.71070 (A), (Δρ)max = 0.322, (Δρ)min = -0.330 e/(A)3, the final R = 0.0563 and wR = 0.1058 for 3434 observed reflections with I > 2σ(I).

  15. 1-[(Anthracen-9-yl)carbon-yl]-2,7-di-meth-oxy-naphthalene: a chain-like structure composed of face-to-face type dimeric mol-ecular aggregates.

    Science.gov (United States)

    Siqingaowa; Tsumuki, Takehiro; Ogata, Kazuki; Yonezawa, Noriyuki; Okamoto, Akiko

    2016-12-01

    The asymmetric unit of the title compound, C27H20O3, contains two independent mol-ecules (A and B). The anthracene ring system is connected to the 2,7-di-meth-oxy-naphthalene core in a twisted manner, with dihedral angles of 86.38 (5) and 79.36 (8)°, respectively, for conformers A and B. In the crystal, face-to-face type dimeric mol-ecular aggregates of each conformer are observed. The dimer of conformer A is formed by two pairs of C-H⋯π inter-actions, and that of conformer B by a pair of (sp(2))C-H⋯O hydrogen bonds. The dimers of conformer A are linked to each other via a π-π stacking inter-action between the anthracene rings to form a chain along the b axis and the chains are aligned along the c axis, forming a sheet structure. The dimers of conformer B are connected to each other via a couple of C-H⋯π inter-actions to form a chain along the b axis. The chains are aligned along the c axis through (sp(2))C-H⋯O=C hydrogen bonds, forming a sheet parallel to the bc plane. The sheets of conformers A and B are alternately stacked along the a axis via two kinds of inter-molecular (sp(2))C-H⋯O=C hydrogen bonds.

  16. Band structure characteristics of T-square fractal phononic crystals

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Jian; Fan You-Hua

    2013-01-01

    The T-square fractal two-dimensional phononic crystal model is presented in this article.A comprehensive study is performed for the Bragg scattering and locally resonant fractal phononic crystal.We find that the band structures of the fractal and non-fractal phononic crystals at the same filling ratio are quite different through using the finite element method.The fractal design has an important impact on the band structures of the two-dimensional phononic crystals.

  17. Crystal structure of yeast Sco1

    Energy Technology Data Exchange (ETDEWEB)

    Abajian, Carnie; Rosenzweig, Amy C. (NWU)

    2010-03-05

    The Sco family of proteins are involved in the assembly of the dinuclear CuA site in cytochrome c oxidase (COX), the terminal enzyme in aerobic respiration. These proteins, which are found in both eukaryotes and prokaryotes, are characterized by a conserved CXXXC sequence motif that binds copper ions and that has also been proposed to perform a thiol:disulfide oxidoreductase function. The crystal structures of Saccharomyces cerevisiae apo Sco1 (apo-ySco1) and Sco1 in the presence of copper ions (Cu-ySco1) were determined to 1.8- and 2.3-{angstrom} resolutions, respectively. Yeast Sco1 exhibits a thioredoxin-like fold, similar to that observed for human Sco1 and a homolog from Bacillus subtilis. The Cu-ySco1 structure, obtained by soaking apo-ySco1 crystals in copper ions, reveals an unexpected copper-binding site involving Cys181 and Cys216, cysteine residues present in ySco1 but not in other homologs. The conserved CXXXC cysteines, Cys148 and Cys152, can undergo redox chemistry in the crystal. An essential histidine residue, His239, is located on a highly flexible loop, denoted the Sco loop, and can adopt positions proximal to both pairs of cysteines. Interactions between ySco1 and its partner proteins yeast Cox17 and yeast COX2 are likely to occur via complementary electrostatic surfaces. This high-resolution model of a eukaryotic Sco protein provides new insight into Sco copper binding and function.

  18. Crystal structure of (1S,3R,8R,9S,10R)-10-bromo-methyl-2,2-di-chloro-9,10-ep-oxy-3,7,7-tri-methyl-tri-cyclo-[6.4.0.0(1,3)]dodeca-ne.

    Science.gov (United States)

    Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2015-05-01

    The title compound, C16H23BrCl2O, was synthesized in three steps from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (cedrus atlantica). The mol-ecule is built up from two fused six- and seven-membered rings, each linked to a three-membered ring. The six-membered ring has a screw-boat conformation, whereas the seven-membered ring displays a twist-boat conformation. The absolute structure was established unambiguously from anomalous dispersion effects.

  19. Modeling of photonic crystal waveguide structures

    Science.gov (United States)

    Richter, Ivan; Kwiecien, Pavel; Šiňor, Milan; Haiduk, Adam

    2007-05-01

    Photonic crystal (PhC) structures and photonic structures based on them represent nowadays very promising structures of artificial origin. Since they exhibit very specific properties and characteristics that can be very difficult (or even impossible) to realize by other means, they represent a significant part of new artificially made metamaterial classes. For studying and modeling properties of PhC structures, we have applied, implemented and partially improved various complementary techniques: the 2D plane wave expansion (PWE) method, and the 2D finite-difference time-domain (FDTD) method with perfectly matched layers. Also, together with these in-house methods, other tools available in the field have been applied, including, e.g. MIT MPB (PWE), F2P (FDTD) and CAMFR (bidirectional expansion and propagation mode matching method) packages. We have applied these methods to several PhC waveguide structure examples, studying the effects of varying the key parameters and geometry. Such a study is relevant for proper understanding of physical mechanisms and for optimization and fabrication recommendations. Namely, in this contribution, we have concentrated on several examples of PhC waveguide structure simulations, of two types of guides (dielectric-rode type and air-hole type), with several geometries: rectangular lattice with either rectangular or chessboard inclusions. The modeling results are compared and discussed.

  20. Temperature dependent spin structures in Hexaferrite crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chao, Y.C. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan (China); Lin, J.G., E-mail: jglin@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan (China); Chun, S.H.; Kim, K.H. [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2016-01-01

    In this work, the Hexaferrite Ba{sub 0.5}Sr{sub 1.5}Zn{sub 2}Fe{sub 12}O{sub 22} (BSZFO) is studied due to its interesting characteristics of long-wavelength spin structure. Ferromagnetic resonance (FMR) is used to probe the magnetic states of BSZFO single crystal and its temperature dependence behavior is analyzed by decomposing the multiple lines of FMR spectra into various phases. Distinguished phase transition is observed at 110 K for one line, which is assigned to the ferro(ferri)-magnetic transition from non-collinear to collinear spin state. - Highlights: • For the first time Ferromagnetic Resonance is used to probe the local magnetic structure of Ba{sub 0.5}Sr{sub 1.5}Zn{sub 2}Fe{sub 12}O{sub 22.} • The multiphases in the single crystal is identified, which provides important information toward its future application for the magnetoelectric devices.

  1. Syntheses and Crystal Structures of Ferrocenoindenes

    Directory of Open Access Journals (Sweden)

    Gerhard Laus

    2013-02-01

    Full Text Available Ferrocenoindenes display planar chirality and thus represent valuable ligands for asymmetric catalysis. Here, we report on the synthesis of novel 3-(1,1-dibromomethyleneferroceno[1,2-a]indene, (Z-3-(1-bromomethylene-6-iodoferroceno[1,2-a]indene, and benzo[5,6-f]ferroceno[2,3,a]inden-1-one. Any application-oriented design of chiral catalysts requires fundamental knowledge about the ligands involved, not only in terms of atom-connectivity, but also in terms of their three-dimensional structure and steric demand. Therefore, the crystal structures of 2-ferrocenylbenzoic acid, ferroceno[1,2-a]indene, and (Z-3-(1-bromomethylene-6-iodoferroceno[1,2-a]indene have been determined. The bond-lengths that can be retrieved therefrom also allow for an estimation of the reactivity of the aryl-iodo, bromo-methylidene and dibromomethylidene moieties.

  2. Crystal structure of human nicotinamide riboside kinase.

    Science.gov (United States)

    Khan, Javed A; Xiang, Song; Tong, Liang

    2007-08-01

    Nicotinamide riboside kinase (NRK) has an important role in the biosynthesis of NAD(+) as well as the activation of tiazofurin and other NR analogs for anticancer therapy. NRK belongs to the deoxynucleoside kinase and nucleoside monophosphate (NMP) kinase superfamily, although the degree of sequence conservation is very low. We report here the crystal structures of human NRK1 in a binary complex with the reaction product nicotinamide mononucleotide (NMN) at 1.5 A resolution and in a ternary complex with ADP and tiazofurin at 2.7 A resolution. The active site is located in a groove between the central parallel beta sheet core and the LID and NMP-binding domains. The hydroxyl groups on the ribose of NR are recognized by Asp56 and Arg129, and Asp36 is the general base of the enzyme. Mutation of residues in the active site can abolish the catalytic activity of the enzyme, confirming the structural observations.

  3. Crystal Structure of Human Nicotinamide Riboside Kinase

    Energy Technology Data Exchange (ETDEWEB)

    Khan,J.; Xiang, S.; Tong, L.

    2007-01-01

    Nicotinamide riboside kinase (NRK) has an important role in the biosynthesis of NAD{sup +} as well as the activation of tiazofurin and other NR analogs for anticancer therapy. NRK belongs to the deoxynucleoside kinase and nucleoside monophosphate (NMP) kinase superfamily, although the degree of sequence conservation is very low. We report here the crystal structures of human NRK1 in a binary complex with the reaction product nicotinamide mononucleotide (NMN) at 1.5 {angstrom} resolution and in a ternary complex with ADP and tiazofurin at 2.7 {angstrom} resolution. The active site is located in a groove between the central parallel {beta} sheet core and the LID and NMP-binding domains. The hydroxyl groups on the ribose of NR are recognized by Asp56 and Arg129, and Asp36 is the general base of the enzyme. Mutation of residues in the active site can abolish the catalytic activity of the enzyme, confirming the structural observations.

  4. The Crystal Structure of Human Argonaute2

    Energy Technology Data Exchange (ETDEWEB)

    Schirle, Nicole T.; MacRae, Ian J. (Scripps)

    2012-07-18

    Argonaute proteins form the functional core of the RNA-induced silencing complexes that mediate RNA silencing in eukaryotes. The 2.3 angstrom resolution crystal structure of human Argonaute2 (Ago2) reveals a bilobed molecule with a central cleft for binding guide and target RNAs. Nucleotides 2 to 6 of a heterogeneous mixture of guide RNAs are positioned in an A-form conformation for base pairing with target messenger RNAs. Between nucleotides 6 and 7, there is a kink that may function in microRNA target recognition or release of sliced RNA products. Tandem tryptophan-binding pockets in the PIWI domain define a likely interaction surface for recruitment of glycine-tryptophan-182 (GW182) or other tryptophan-rich cofactors. These results will enable structure-based approaches for harnessing the untapped therapeutic potential of RNA silencing in humans.

  5. Structural Transitions in Cholesteric Liquid Crystal Droplets

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ye; Bukusoglu, Emre; Martinez-Gonzalez, Jose A.; Rahimi, Mohammad; Roberts, Tyler F.; Zhang, Rui; Wang, Xiaoguang; Abbott, Nicholas L.; de Pablo, Juan J.

    2016-07-01

    Confinement of cholesteric liquid crystals (ChLC) into droplets leads to a delicate interplay between elasticity, chirality, and surface energy. In this work, we rely on a combination of theory and experiments to understand the rich morphological behavior that arises from that balance. More specifically, a systematic study of micrometer-sized ChLC droplets is presented as a function of chirality and surface energy (or anchoring). With increasing chirality, a continuous transition is observed from a twisted bipolar structure to a radial spherical structure, all within a narrow range of chirality. During such a transition, a bent structure is predicted by simulations and confirmed by experimental observations. Simulations are also able to capture the dynamics of the quenching process observed in experiments. Consistent with published work, it is found that nanoparticles are attracted to defect regions on the surface of the droplets. For weak anchoring conditions at the nanoparticle surface, ChLC droplets adopt a morphology similar to that of the equilibrium helical phase observed for ChLCs in the bulk. As the anchoring strength increases, a planar bipolar structure arises, followed by a morphological transition to a bent structure. The influence of chirality and surface interactions are discussed in the context of the potential use of ChLC droplets as stimuli-responsive materials for reporting molecular adsorbates.

  6. Crystal structure of bis-(2,2'-bi-pyridine)[N'-(quino-lin-2-ylmethylidene)pyridine-2-carbohydrazide]ruthenium(II) bis(tetra-fluorido-borate) di-chloro-methane tris-olvate.

    Science.gov (United States)

    Mori, Asami; Suzuki, Takayoshi; Nakajima, Kiyohiko

    2015-02-01

    The title compound, [Ru(C10H8N2)2(C16H12N4O)](BF4)2·3CH2Cl2, crystallizes with one complex dication, two BF4 (-) counter-anions and three di-chloro-methane solvent mol-ecules in the asymmetric unit. The central Ru(II) atom adopts a distorted octa-hedral coordination sphere with two 2,2'-bi-pyridine (bpy) and one quinoline-2-carbaldehyde (pyridine-2-carbon-yl)hydrazone (HL) ligand. The hydrazone ligand has a Z form and coordinates to the Ru(II) atom via the amide-O and imine-N atoms, affording a planar five-membered chelate ring, while its pyridine-N and quinoline-N donor atoms in the substituents are non-coordinating. The hydrazone N-H group forms an intra-molecular hydrogen bond with the quinoline-N atom. In the crystal, the quinoline moiety of HL shows the shortest π-π stacking inter-action with the pyridine substituent of HL in a neighbouring complex, the centroid-to-centroid distance being 3.793 (3) Å.

  7. Crystal structure of strontium dinickel iron orthophosphate

    Directory of Open Access Journals (Sweden)

    Said Ouaatta

    2015-10-01

    Full Text Available The title compound, SrNi2Fe(PO43, synthesized by solid-state reaction, crystallizes in an ordered variant of the α-CrPO4 structure. In the asymmetric unit, two O atoms are in general positions, whereas all others atoms are in special positions of the space group Imma: the Sr cation and one P atom occupy the Wyckoff position 4e (mm2, Fe is on 4b (2/m, Ni and the other P atom are on 8g (2, one O atom is on 8h (m and the other on 8i (m. The three-dimensional framework of the crystal structure is built up by [PO4] tetrahedra, [FeO6] octahedra and [Ni2O10] dimers of edge-sharing octahedra, linked through common corners or edges. This structure comprises two types of layers stacked alternately along the [100] direction. The first layer is formed by edge-sharing octahedra ([Ni2O10] dimer linked to [PO4] tetrahedra via common edges while the second layer is built up from a strontium row followed by infinite chains of alternating [PO4] tetrahedra and FeO6 octahedra sharing apices. The layers are held together through vertices of [PO4] tetrahedra and [FeO6] octahedra, leading to the appearance of two types of tunnels parallel to the a- and b-axis directions in which the Sr cations are located. Each Sr cation is surrounded by eight O atoms.

  8. Crystal structures of five 6-mercaptopurine derivatives

    Directory of Open Access Journals (Sweden)

    Lígia R. Gomes

    2016-03-01

    Full Text Available The crystal structures of five 6-mercaptopurine derivatives, viz. 2-[(9-acetyl-9H-purin-6-ylsulfanyl]-1-(3-methoxyphenylethan-1-one (1, C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-ylsulfanyl]-1-(4-methoxyphenylethan-1-one (2, C16H14N4O3S, 2-[(9-acetyl-9H-purin-6-ylsulfanyl]-1-(4-chlorophenylethan-1-one (3, C15H11ClN4O2S, 2-[(9-acetyl-9H-purin-6-ylsulfanyl]-1-(4-bromophenylethan-1-one (4, C15H11BrN4O2S, and 1-(3-methoxyphenyl-2-[(9H-purin-6-ylsulfanyl]ethan-1-one (5, C14H12N4O2S. Compounds (2, (3 and (4 are isomorphous and accordingly their molecular and supramolecular structures are similar. An analysis of the dihedral angles between the purine and exocyclic phenyl rings show that the molecules of (1 and (5 are essentially planar but that in the case of the three isomorphous compounds (2, (3 and (4, these rings are twisted by a dihedral angle of approximately 38°. With the exception of (1 all molecules are linked by weak C—H...O hydrogen bonds in their crystals. There is π–π stacking in all compounds. A Cambridge Structural Database search revealed the existence of 11 deposited compounds containing the 1-phenyl-2-sulfanylethanone scaffold; of these, only eight have a cyclic ring as substituent, the majority of these being heterocycles.

  9. Crystal Structures of Respiratory Pathogen Neuraminidases

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, Y.; Parker, D; Ratner, A; Prince, A; Tong, L

    2009-01-01

    Currently there is pressing need to develop novel therapeutic agents for the treatment of infections by the human respiratory pathogens Pseudomonas aeruginosa and Streptococcus pneumoniae. The neuraminidases of these pathogens are important for host colonization in animal models of infection and are attractive targets for drug discovery. To aid in the development of inhibitors against these neuraminidases, we have determined the crystal structures of the P. aeruginosa enzyme NanPs and S. pneumoniae enzyme NanA at 1.6 and 1.7 {angstrom} resolution, respectively. In situ proteolysis with trypsin was essential for the crystallization of our recombinant NanA. The active site regions of the two enzymes are strikingly different. NanA contains a deep pocket that is similar to that in canonical neuraminidases, while the NanPs active site is much more open. The comparative studies suggest that NanPs may not be a classical neuraminidase, and may have distinct natural substrates and physiological functions. This work represents an important step in the development of drugs to prevent respiratory tract colonization by these two pathogens.

  10. Extraction and Crystal Structure of Karounidiol

    Institute of Scientific and Technical Information of China (English)

    巢志茂; 王诚

    2003-01-01

    The title compound of karounidiol (C30H48O2), a main active triterpene component of snakegourd seed, was isolated from unsaponifiable matter of the seed oil of Trichosanthes kirilowii Maxim., and characterized by X-ray diffraction analysis. It crystallizes in orthorhombic system, space group P212121 with C30H48O2·CH3OH·H2O (C31H54O4), a = 7.515(1), b = 14.407(1), c = 27.799(2) (A。), V = 3009.8(5)(A。)3, Z = 4, Dx = 1.087 g/cm3, Mr = 490.77, F(000) = 1088 and μ = 0.086 mm-1. The final R = 0.0840 and wR = 0.2289 for 2752 observed reflections (|F|2 ≥ 2σ|F|2). The molecular crystal structure of karounidiol shows relative stereochemistry of (3α,13α,14β, 20α)-3,29-dihydroxy-13-methyl-26-norolean-7,9(11)-diene. The molecule is composed of five six- membered rings with ring junctures of A/B trans, C/D trans and D/E cis.

  11. Crystal and molecular structure of aflatrem

    Directory of Open Access Journals (Sweden)

    Bruno N. Lenta

    2015-11-01

    Full Text Available The crystal structure of the title compound, C32H39NO4, confirms the absolute configuration of the seven chiral centres in the molecule. The molecule has a 1,1-dimethylprop-2-enyl substituent on the indole nucleus and this nucleus shares one edge with the five-membered ring which is, in turn, connected to a sequence of three edge-shared fused rings. The skeleton is completed by the 7,7-trimethyl-6,8-dioxabicyclo[3.2.1]oct-3-en-2-one group connected to the terminal cyclohexene ring. The two cyclohexane rings adopt chair and half-chair conformations, while in the dioxabicyclo[3.2.1]oct-3-en-2-one unit, the six-membered ring has a half-chair conformation. The indole system of the molecule exhibits a tilt of 2.02 (1° between its two rings. In the crystal, O—H...O hydrogen bonds connect molecules into chains along [010]. Weak N—H...π interactions connect these chains, forming sheets parallel to (10-1.

  12. The crystal structure Escherichia coli Spy.

    Science.gov (United States)

    Kwon, Eunju; Kim, Dong Young; Gross, Carol A; Gross, John D; Kim, Kyeong Kyu

    2010-11-01

    Escherichia coli spheroplast protein y (EcSpy) is a small periplasmic protein that is homologous with CpxP, an inhibitor of the extracytoplasmic stress response. Stress conditions such as spheroplast formation induce the expression of Spy via the Cpx or the Bae two-component systems in E. coli, though the function of Spy is unknown. Here, we report the crystal structure of EcSpy, which reveals a long kinked hairpin-like structure of four α-helices that form an antiparallel dimer. The dimer contains a curved oval shape with a highly positively charged concave surface that may function as a ligand binding site. Sequence analysis reveals that Spy is highly conserved over the Enterobacteriaceae family. Notably, three conserved regions that contain identical residues and two LTxxQ motifs are placed at the horizontal end of the dimer structure, stabilizing the overall fold. CpxP also contains the conserved sequence motifs and has a predicted secondary structure similar to Spy, suggesting that Spy and CpxP likely share the same fold.

  13. Crystal structure of zirconia by Rietveld refinement

    Institute of Scientific and Technical Information of China (English)

    王大宁; 郭永权; 梁开明; 陶琨

    1999-01-01

    The crystal structures and phase transformation of zirconia ceramics have been investigated by means of X-ray powder diffraction and Rietveld powder diffraction profile fitting technique. A structural transition from monoclinic to tetragonal occurs when Y2O3 and CeO2 are doped into zirconia. The space group of the tetragonal structure is P42/nmc, Z=2. The lattice parameters are α=0.362 6(5) nm, c=0.522 6(3)nm for CeO2 doped zirconia and α=0. 360 2(8)nm, c=0. 517 9(1)nm for Y2O3 doped zirconia, respectively. In each unit cell, there are two kinds of equivalent positions, i. e. 2b and 4d, which are occupied by Zr4+, M(M=Y3+, Ce4+) cations and O2- anions, respectively. The crystallographic correlation among the cubic, tetragonal and monoclinic structures of ZrO2 is discussed.

  14. Crystal structure of phenyl N-(4-nitrophenylcarbamate

    Directory of Open Access Journals (Sweden)

    Y. AaminaNaaz

    2015-12-01

    Full Text Available The asymmetric unit of the title compound, C13H10N2O4, contains two independent molecules (A and B. The dihedral angle between the aromatic rings is 48.18 (14° in molecule A and 45.81 (14° in molecule B. The mean plane of the carbamate N—C(=O—O group is twisted slightly from the attached benzene and phenyl rings, making respective dihedral angles of 12.97 (13 and 60.93 (14° in A, and 23.11 (14 and 59.10 (14° in B. In the crystal, A and B molecules are arranged alternately through N—H...O hydrogen bonds and C—H...π interactions, forming chains along the a axis. The chains are further linked by C—H...O hydrogen bonds into a double-chain structure.

  15. New Tricks of the Trade for Crystal Structure Refinement.

    Science.gov (United States)

    Li, Jinjin; Abramov, Yuriy A; Doherty, Michael F

    2017-07-26

    Accurate crystal structures and their experimental uncertainties, determined by X-ray diffraction/neutron diffraction techniques, are vital for crystal engineering studies, such as polymorph stability and crystal morphology calculations. Because of differences in crystal growth and data measurement conditions, crystallographic databases often contain multiple entries of varying quality of the same compound. The choice of the most reliable and best quality crystal structure from many very similar structures remains an unresolved problem, especially for nonexperts. In addition, while crystallographers can make use of some professional software (i.e., Materials Studio) for structure refinement, noncrystallographers may not have access to it. In the present paper, we propose a simple method to study the sensitivity of the crystal lattice energy to changes in the structural parameters, which creates a diagnostic tool to test the quality of crystal structure files and to improve the low-quality structures based on lattice energy distribution. Thus, noncrystallographers could take the proposed idea and program/optimize crystal structure by themselves. They can have their in-house program to determine the reliability of the selected crystal data and then use the best quality data or carry out structural optimization for low-quality data. The proposed method will benefit a broad cross-section of scientific researchers, especially those in solid-state and physical chemistry.

  16. Stability of orientationally disordered crystal structures of colloidal hard dumbbells.

    Science.gov (United States)

    Marechal, Matthieu; Dijkstra, Marjolein

    2008-06-01

    We study the stability of orientationally disordered crystal phases in a suspension of colloidal hard dumbbells using Monte Carlo simulations. For dumbbell bond length L/sigmafcc structure for a large part of the stable plastic crystal regime. In addition, we study the stability of an orientationally disordered aperiodic crystal structure in which the spheres of the dumbbells are on a random-hexagonal-close-packed lattice, and the dumbbells are formed by taking random pairs of neighboring spheres. Using free-energy calculations, we determine the fluid-aperiodic crystal and periodic-aperiodic crystal coexistence regions for L/sigma>0.88 .

  17. Affine structures and a tableau model for E_6 crystals

    CERN Document Server

    Jones, Brant

    2009-01-01

    We provide the unique affine crystal structure for type E_6^{(1)} Kirillov-Reshetikhin crystals corresponding to the multiples of fundamental weights s Lambda_1, s Lambda_2, and s Lambda_6 for all s \\geq 1 (in Bourbaki's labeling of the Dynkin nodes, where 2 is the adjoint node). Our methods introduce a generalized tableaux model for classical highest weight crystals of type E and use the order three automorphism of the affine E_6^{(1)} Dynkin diagram. In addition, we provide a conjecture for the affine crystal structure of type E_7^{(1)} Kirillov-Reshetikhin crystals corresponding to the adjoint node.

  18. Isomorph invariance of the structure and dynamics of classical crystals

    DEFF Research Database (Denmark)

    Albrechtsen, Dan; Olsen, Andreas Elmerdahl; Pedersen, Ulf Rørbæk

    2014-01-01

    of a defective fcc crystal is also shown to be isomorph invariant. In contrast, a NaCl crystal model does not exhibit isomorph invariances. Other systems simulated, though in less detail, are the Wahnström binary Lennard-Jones crystal with the MgZn2 Laves crystal structure, monatomic fcc crystals of particles......This paper shows by computer simulations that some crystalline systems have curves in their thermodynamic phase diagrams, so-called isomorphs, along which structure and dynamics in reduced units are invariant to a good approximation. The crystals are studied in a classical-mechanical framework......, which is generally a good description except significantly below melting. The existence of isomorphs for crystals is validated by simulations of particles interacting via the Lennard-Jones pair potential arranged into a face-centered cubic (fcc) crystalline structure; the slow vacancy-jump dynamics...

  19. 4-Amino-pyridinium 5-carb-oxy-penta-noate monohydrate.

    Science.gov (United States)

    Raj, S Alfred Cecil; Sinthiya, A; Varghese, Babu

    2012-07-01

    In the title hydrated salt, C(5)H(7)N(2) (+)·C(6)H(9)O(4) (-)·H(2)O, the carb-oxy H atom is disordered over two positions with equal occupancy. In the crystal, O atoms of the 5-carb-oxy-penta-noate anion link the 4-amino-pyridinium cations and water mol-ecules into a three-dimensional network via N-H⋯O hydrogen bonds. The crystal structure is further consolidated by O-H⋯O hydrogen bonds involving the anion and the solvent water mol-ecule.

  20. N-(2,5-Dimethyl-phen-yl)-2-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-12-01

    In the crystal structure of the title compound, C14H14N2O4S, the N-H bond is syn to the ortho-nitro group in the sulfonyl benzene ring and anti to the ortho- and syn to the meta-methyl groups in the aniline ring. The mol-ecule is twisted at the S-N bond with a torsion angle of 71.41 (18)°. The dihedral angle between the planes of the benzene rings is 51.07 (8)°. In the crystal, pairs of N-H⋯Osulfonamide hydrogen bonds link the mol-ecules into inversion dimers.

  1. N-(4-Chloro-phenyl-sulfon-yl)-2-methyl-propanamide.

    Science.gov (United States)

    Nirmala, P G; Foro, Sabine; Gowda, B Thimme

    2011-09-01

    In the crystal structure of the title compound, C(10)H(12)ClNO(3)S, the N-C bond in the C-SO(2)-NH-C segment has a gauche torsion with respect to the S=O bonds. The mol-ecule is twisted at the S atom with a C-S-N-C torsion angle of -62.3 (3)°. The benzene ring and the SO(2)-NH-CO-C segment form a dihedral angle of 89.3 (1)°. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds into inversion dimers.

  2. Revisiting the blind tests in crystal structure prediction: accurate energy ranking of molecular crystals.

    Science.gov (United States)

    Asmadi, Aldi; Neumann, Marcus A; Kendrick, John; Girard, Pascale; Perrin, Marc-Antoine; Leusen, Frank J J

    2009-12-24

    In the 2007 blind test of crystal structure prediction hosted by the Cambridge Crystallographic Data Centre (CCDC), a hybrid DFT/MM method correctly ranked each of the four experimental structures as having the lowest lattice energy of all the crystal structures predicted for each molecule. The work presented here further validates this hybrid method by optimizing the crystal structures (experimental and submitted) of the first three CCDC blind tests held in 1999, 2001, and 2004. Except for the crystal structures of compound IX, all structures were reminimized and ranked according to their lattice energies. The hybrid method computes the lattice energy of a crystal structure as the sum of the DFT total energy and a van der Waals (dispersion) energy correction. Considering all four blind tests, the crystal structure with the lowest lattice energy corresponds to the experimentally observed structure for 12 out of 14 molecules. Moreover, good geometrical agreement is observed between the structures determined by the hybrid method and those measured experimentally. In comparison with the correct submissions made by the blind test participants, all hybrid optimized crystal structures (apart from compound II) have the smallest calculated root mean squared deviations from the experimentally observed structures. It is predicted that a new polymorph of compound V exists under pressure.

  3. Some Lower Valence Vanadium Fluorides: Their Crystal Distortions, Domain Structures, Modulated Structures, Ferrimagnetism, and Composition Dependence.

    Science.gov (United States)

    Hong, Y. S.; And Others

    1980-01-01

    Describes some contemporary concepts unique to the structure of advanced solids, i.e., their crystal distortions, domain structures, modulated structures, ferrimagnetism, and composition dependence. (Author/CS)

  4. Polymorphic crystal structures of an all-AT DNA dodecamer.

    Science.gov (United States)

    Acosta-Reyes, Francisco J; Subirana, Juan A; Pous, Joan; Sánchez-Giraldo, Raquel; Condom, Núria; Baldini, Roberto; Malinina, Lucy; Campos, J Lourdes

    2015-03-01

    In this work, we explore the influence of different solvents and ions on the crystallization behavior of an all-AT dodecamer d(AATAAATTTATT)2 In all cases, the oligonucleotides are found as continuous columns of stacked duplexes. The spatial organization of such columns is variable; consequently we have obtained seven different crystal forms. The duplexes can be made to crystallize in either parallel or crossed columns. Such versatility in the formation of a variety of crystal forms is characteristic for this sequence. It had not been previously reported for any other sequence. In all cases, the oligonucleotide duplexes have been found to crystallize in the B form. The crystallization conditions determine the organization of the crystal, although no clear local interactions have been detected. Mg(2+) and Ni(2+) can be used in order to obtain compact crossed structures. DNA-DNA interactions in the crystals of our all-AT duplexes present crossovers which are different from those previously reported for mixed sequence oligonucleotides. Our results demonstrate that changes in the ionic atmosphere and the crystallization solvent have a strong influence on the DNA-DNA interactions. Similar ionic changes will certainly influence the biological activity of DNA. Modulation of the crystal structure by ions should also be explored in DNA crystal engineering. Liquid crystals with a peculiar macroscopic shape have also been observed.

  5. Crystallization and Structure Determination of Superantigens and Immune Receptor Complexes.

    Science.gov (United States)

    Rödström, Karin E J; Lindkvist-Petersson, Karin

    2016-01-01

    Structure determination of superantigens and the complexes they form with immune receptors have over the years provided insight in their modes of action. This technique requires growing large and highly ordered crystals of the superantigen or receptor-superantigen complex, followed by exposure to X-ray radiation and data collection. Here, we describe methods for crystallizing superantigens and superantigen-receptor complexes using the vapor diffusion technique, how the crystals may be optimized, and lastly data collection and structure determination.

  6. Crystal structure refinement a crystallographers guide to SHELXL

    CERN Document Server

    2006-01-01

    A crystallographers guide to SHELXL, covering various aspects of practical crystal structure refinement, from the treatment of hydrogen atoms to the assignment of atom types, and more. After an introduction to SHELXL, a brief survey of crystal structure refinement is provided.

  7. The Crystal Structure of Cu4Bi4Se9

    DEFF Research Database (Denmark)

    Makovicky, E.; Søtofte, Inger; Karup-Møller, S.

    2002-01-01

    The crystal structure Of Cu4Bi4Se9,, synthesized at 400 degreesC, was determined from single crystal X-ray diffraction data and refined to the R, value of 0.05. The compound is orthorhombic, with a = 32.692 Angstrom, b = 4.120 Angstrom, and c = 12.202 Angstrom, space group Pnma. The structure...

  8. Undergraduates Improve upon Published Crystal Structure in Class Assignment

    Science.gov (United States)

    Horowitz, Scott; Koldewey, Philipp; Bardwell, James C.

    2014-01-01

    Recently, 57 undergraduate students at the University of Michigan were assigned the task of solving a crystal structure, given only the electron density map of a 1.3 Å crystal structure from the electron density server, and the position of the N-terminal amino acid. To test their knowledge of amino acid chemistry, the students were not given the…

  9. The Crystal Structure of Cu4Bi4Se9

    DEFF Research Database (Denmark)

    Makovicky, E.; Søtofte, Inger; Karup-Møller, S.

    2002-01-01

    The crystal structure Of Cu4Bi4Se9,, synthesized at 400 degreesC, was determined from single crystal X-ray diffraction data and refined to the R, value of 0.05. The compound is orthorhombic, with a = 32.692 Angstrom, b = 4.120 Angstrom, and c = 12.202 Angstrom, space group Pnma. The structure...

  10. CCDC 1416891: Experimental Crystal Structure Determination : Methyl-triphenyl-germanium

    KAUST Repository

    Bernatowicz, Piotr

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  11. 4-(4-Chloro-phen-yl)-6-hydr-oxy-5-(2-thienyl-carbonyl)-6-(trifluoro-meth-yl)-3,4,5,6-tetra-hydro-pyrimidin-2(1H)-one monohydrate.

    Science.gov (United States)

    Mosslemin, Mohammad Hossein; Nateghi, Mohammad Reza; Sadoughi, Hesamaddin; Lamei, Asal

    2009-05-20

    The asymmetric unit of the title compound, C(16)H(12)ClF(3)N(2)O(3)S·H(2)O, contains two crystallographically independent organic mol-ecules and two water mol-ecules. The organic species are linked by an inter-molecular O-H⋯O hydrogen bond, while the water mol-ecules are connected to them through inter-molecular O-H⋯N hydrogen bonds. The thio-phene and phenyl rings are oriented at dihedral angles of 62.35 (4) in the first independent mol-ecule and 60.74 (5)° in the second, while the pyrimidine rings adopt twisted conformations in both molecules. Intra-molecular N-H⋯F inter-actions result in the formation of two five-membered rings having envelope conformations. In the crystal structure, further inter-molecular O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules into chains.

  12. Use of Pom Pons to Illustrate Cubic Crystal Structures.

    Science.gov (United States)

    Cady, Susan G.

    1997-01-01

    Describes a method that uses olefin pom pons to illustrate cubic crystal structure. Facilitates hands-on examination of different packing arrangements such as hexagonal close-packed and cubic close-packed structures. (JRH)

  13. High-speed prediction of crystal structures for organic molecules

    Science.gov (United States)

    Obata, Shigeaki; Goto, Hitoshi

    2015-02-01

    We developed a master-worker type parallel algorithm for allocating tasks of crystal structure optimizations to distributed compute nodes, in order to improve a performance of simulations for crystal structure predictions. The performance experiments were demonstrated on TUT-ADSIM supercomputer system (HITACHI HA8000-tc/HT210). The experimental results show that our parallel algorithm could achieve speed-ups of 214 and 179 times using 256 processor cores on crystal structure optimizations in predictions of crystal structures for 3-aza-bicyclo(3.3.1)nonane-2,4-dione and 2-diazo-3,5-cyclohexadiene-1-one, respectively. We expect that this parallel algorithm is always possible to reduce computational costs of any crystal structure predictions.

  14. Crystal structure of di-chlorido-{4-[(E)-(meth-oxy-imino-κN)meth-yl]-1,3-thia-zol-2-amine-κN (3)}palladium(II).

    Science.gov (United States)

    Dyakonenko, Viktorita V; Zholob, Olga O; Orysyk, Svitlana I; Pekhnyo, Vasily I

    2015-01-01

    In the title compound, [PdCl2(C5H7N3OS)], the Pd(II) atom adopts a distorted square-planar coordination sphere defined by two N atoms of the bidentate ligand and two Cl atoms. The mean deviation from the coordination plane is 0.029 Å. The methyl group is not coplanar with the plane of the metallacycle [torsion angle C-O-N-C = 20.2 (4)°]. Steric repulsion between the methyl group and atoms of the metallacycle is manifested by shortened intra-molecular H⋯C contacts of 2.27, 2.38 and 2.64 Å, as compared with the sum of the van der Waals radii of 2.87 Å. The amino group participates via one H atom in the formation of an intra-molecular N-H⋯Cl hydrogen bond. In the crystal, the other H atom of the amino group links mol-ecules via bifurcated N-H⋯(Cl,O) hydrogen bonds into chains parallel to [001].

  15. Crystal structure of ethyl (2S,2'R)-1'-benzyl-3-oxo-3H-di-spiro-[1-benzo-thio-phene-2,3'-pyrrolidine-2',11''-indeno[1,2-b]quinoxaline]-4'-carboxyl-ate.

    Science.gov (United States)

    Govindaraj, J; Raja, R; Suresh, M; Raghunathan, R; SubbiahPandi, A

    2015-03-01

    In the title compound, C35H27N3O3S, the spiro-linked five-membered rings both adopt twisted conformations. The pyrrolidine ring makes dihedral angles of 80.5 (1) and 77.4 (9)° with the benzo-thio-phene ring system and the quinoxaline ring system, respectively. The S atom and C=O unit of the benzo-thio-phene ring system are disordered over two opposite orientations in a 0.768 (4):0.232 (4) ratio. The atoms of the ethyl side chain are disordered over two sets of sites in a 0.680 (16):0.320 (16) ratio. In the crystal, mol-ecules are linked by C-H⋯O, C-H⋯N and π-π inter-actions [shortest centroid-centroid distance = 3.4145 (19) Å], resulting in a three-dimensional network.

  16. Evolutionary crystal structure prediction and novel high-pressure phases

    OpenAIRE

    Oganov, A. R.; Ma, Y.; Lyakhov, A. O.; Valle, M.; C. Gatti

    2010-01-01

    Prediction of stable crystal structures at given pressure-temperature conditions, based only on the knowledge of the chemical composition, is a central problem of condensed matter physics. This extremely challenging problem is often termed "crystal structure prediction problem", and recently developed evolutionary algorithm USPEX (Universal Structure Predictor: Evolutionary Xtallography) made an important progress in solving it, enabling efficient and reliable prediction of structures with up...

  17. PLANAR OPTICAL WAVEGUIDES WITH PHOTONIC CRYSTAL STRUCTURE

    DEFF Research Database (Denmark)

    2003-01-01

    Planar optical waveguide comprising a core region and a cladding region comprising a photonic crystal material, said photonic crystal material having a lattice of column elements, wherein at least a number of said column elements are elongated substantially in an axial direction for said core reg...

  18. Crystal structure of Clostridium difficile toxin A

    Energy Technology Data Exchange (ETDEWEB)

    Chumbler, Nicole M.; Rutherford, Stacey A.; Zhang, Zhifen; Farrow, Melissa A.; Lisher, John P.; Farquhar, Erik; Giedroc, David P.; Spiller, Benjamin W.; Melnyk, Roman A.; Lacy, D. Borden

    2016-01-11

    Clostridium difficile infection is the leading cause of hospital-acquired diarrhoea and pseudomembranous colitis. Disease is mediated by the actions of two toxins, TcdA and TcdB, which cause the diarrhoea, as well as inflammation and necrosis within the colon. The toxins are large (308 and 270 kDa, respectively), homologous (47% amino acid identity) glucosyltransferases that target small GTPases within the host. The multidomain toxins enter cells by receptor-mediated endocytosis and, upon exposure to the low pH of the endosome, insert into and deliver two enzymatic domains across the membrane. Eukaryotic inositol-hexakisphosphate (InsP6) binds an autoprocessing domain to activate a proteolysis event that releases the N-terminal glucosyltransferase domain into the cytosol. Here, we report the crystal structure of a 1,832-amino-acid fragment of TcdA (TcdA1832), which reveals a requirement for zinc in the mechanism of toxin autoprocessing and an extended delivery domain that serves as a scaffold for the hydrophobic α-helices involved in pH-dependent pore formation. A surface loop of the delivery domain whose sequence is strictly conserved among all large clostridial toxins is shown to be functionally important, and is highlighted for future efforts in the development of vaccines and novel therapeutics.

  19. Anisotropic domain structure of KTiOPO4 crystals

    Science.gov (United States)

    Urenski, P.; Lesnykh, M.; Rosenwaks, Y.; Rosenman, G.; Molotskii, M.

    2001-08-01

    Highly anisotropic ferroelectric domain structure is observed in KTiOPO4 (KTP) crystals reversed by low electric field. The applied Miller-Weinreich model for sidewise motion of domain walls indicates that this anisotropy results from the peculiarities of KTP crystal lattice. The domain nuclei of dozen nanometer size, imaged by atomic force microscopy method, demonstrate regular hexagonal forms. The orientation of domain walls of the elementary nuclei coincides with the orientation of the facets of macroscopic KTP crystals. The observed strong domain elongation along one principal crystal axis allows us to improve tailoring of ferroelectric domain engineered structures for nonlinear optical converters.

  20. Spectroscopic, thermal and structural studies on manganous malate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, J., E-mail: smartlabindia@gmail.com; Lincy, A., E-mail: lincymaria@gmail.com; Mahalakshmi, V.; Saban, K. V. [Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College (India)

    2013-01-15

    Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal X-ray diffraction. The crystals are orthorhombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG-DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG-DTA studies is in conformity with the single crystal XRD data.

  1. Crystal structures of the two epimers from the unusual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octa-hydro-7,9a-ep-oxy-pyrrolo-[2,1-a]iso-indole-6-carb-oxy-lic acid, 5a(RS),6(SR),7(RS),9a(SR),9b(SR) and 5a(RS),6(RS),7(RS),9a(SR),9b(SR).

    Science.gov (United States)

    Poplevin, Dmitry S; Zubkov, Fedor I; Dorovatovskii, Pavel V; Zubavichus, Yan V; Khrustalev, Victor N

    2016-10-01

    The isomeric title compounds, C12H13NO4 (Ia) and C12H13NO4 (IIa), the products of an usual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octa-hydro-7,9a-ep-oxy-pyrrolo-[2,1-a]iso-indole-6-carb-oxy-lic acid, represent the two different diastereomers and have very similar mol-ecular geometries. The mol-ecules of both compounds comprise a fused tetra-cyclic system containing four five-membered rings (pyrrolidine, pyrrolidinone, di-hydro-furan and tetra-hydro-furan), all of which adopt the usual envelope conformations. The dihedral angle between the basal planes of the pyrrolidine and pyrrolidinone rings are 14.3 (2) and 16.50 (11)°, respectively, for (Ia) and (IIa). The nitro-gen atom has a slightly pyramidalized geometry [bond-angle sum = 355.9 and 355.3°, for (Ia) and (IIa)], respectively. In the crystal of (Ia), mol-ecules form zigzag-like hydrogen-bonded chains along [010] through strong O-H⋯O hydrogen bonds and are further linked by weak C-H⋯O hydrogen bonds into complex two-tier layers parallel to (100). Unlike (Ia), the crystal of (IIa) contains centrosymmetric cyclic hydrogen-bonded dimers [graph set R(2)2(14)], formed through strong O-H⋯O hydrogen bonds and are further linked by weak C-H⋯O hydrogen bonds into ribbons extending across [101].

  2. SiBr4--prediction and determination of crystal structures.

    Science.gov (United States)

    Wolf, Alexandra K; Glinnemann, Jürgen; Schmidt, Martin U; Tong, Jianwei; Dinnebier, Robert E; Simon, Arndt; Köhler, Jürgen

    2009-06-01

    For SiBr4 no crystal structures have been reported yet. In this work the crystal structures of SiBr4 were predicted by global lattice-energy minimizations using force-field methods. Over an energy range of 5 kJ mol(-1) above the global minimum ten possible structures were found. Two of these structures were experimentally determined from X-ray synchrotron powder diffraction data: The low-temperature beta phase crystallizes in P2(1)/c, the high-temperature alpha phase in Pa3. Temperature-dependant X-ray powder diffraction shows that the phase transition occurs at 168 K.

  3. SiBr4 - Prediction and Determination of Crystal Structures

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, A.; Glinnemann, J; Schmidt, M; Tong, J; Dinnebier, R; Simon, A; Kohler, J

    2009-01-01

    For SiBr4 no crystal structures have been reported yet. In this work the crystal structures of SiBr4 were predicted by global lattice-energy minimizations using force-field methods. Over an energy range of 5 kJ mol-1 above the global minimum ten possible structures were found. Two of these structures were experimentally determined from X-ray synchrotron powder diffraction data: The low-temperature [beta] phase crystallizes in P21/c, the high-temperature [alpha] phase in Pa overline3. Temperature-dependant X-ray powder diffraction shows that the phase transition occurs at 168 K.

  4. Crystallization and Characterization of Galdieria sulphuraria RUBISCO in Two Crystal Forms: Structural Phase Transition Observed in P21 Crystal Form

    Directory of Open Access Journals (Sweden)

    Boguslaw Stec

    2007-10-01

    Full Text Available We have isolated ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCOfrom the red algae Galdieria Sulphuraria. The protein crystallized in two different crystalforms, the I422 crystal form being obtained from high salt and the P21 crystal form beingobtained from lower concentration of salt and PEG. We report here the crystallization,preliminary stages of structure determination and the detection of the structural phasetransition in the P21 crystal form of G. sulphuraria RUBISCO. This red algae enzymebelongs to the hexadecameric class (L8S8 with an approximate molecular weight 0.6MDa.The phase transition in G. sulphuraria RUBISCO leads from two hexadecamers to a singlehexadecamer per asymmetric unit. The preservation of diffraction power in a phasetransition for such a large macromolecule is rare.

  5. Origin and structure of polar domains in doped molecular crystals

    Science.gov (United States)

    Meirzadeh, E.; Azuri, I.; Qi, Y.; Ehre, D.; Rappe, A. M.; Lahav, M.; Kronik, L.; Lubomirsky, I.

    2016-11-01

    Doping is a primary tool for the modification of the properties of materials. Occlusion of guest molecules in crystals generally reduces their symmetry by the creation of polar domains, which engender polarization and pyroelectricity in the doped crystals. Here we describe a molecular-level determination of the structure of such polar domains, as created by low dopant concentrations (<0.5%). The approach comprises crystal engineering and pyroelectric measurements, together with dispersion-corrected density functional theory and classical molecular dynamics calculations of the doped crystals, using neutron diffraction data of the host at different temperatures. This approach is illustrated using centrosymmetric α-glycine crystals doped with minute amounts of different L-amino acids. The experimentally determined pyroelectric coefficients are explained by the structure and polarization calculations, thus providing strong support for the local and global understanding of how different dopants influence the properties of molecular crystals.

  6. Structural Color Patterns by Electrohydrodynamic Jet Printed Photonic Crystals.

    Science.gov (United States)

    Ding, Haibo; Zhu, Cun; Tian, Lei; Liu, Cihui; Fu, Guangbin; Shang, Luoran; Gu, Zhongze

    2017-02-09

    In this work, we demonstrate the fabrication of photonic crystal patterns with controllable morphologies and structural colors utilizing electrohydrodynamic jet (E-jet) printing with colloidal crystal inks. The final shape of photonic crystal units is controlled by the applied voltage signal and wettability of the substrate. Optical properties of the structural color patterns are tuned by the self-assembly of the silica nanoparticle building blocks. Using this direct printing technique, it is feasible to print customized functional patterns composed of photonic crystal dots or photonic crystal lines according to relevant printing mode and predesigned tracks. This is the first report for E-jet printing with colloidal crystal inks. Our results exhibit promising applications in displays, biosensors, and other functional devices.

  7. Novel photonic crystal cavities and related structures.

    Energy Technology Data Exchange (ETDEWEB)

    Luk, Ting Shan

    2007-11-01

    The key accomplishment of this project is to achieve a much more in-depth understanding of the thermal emission physics of metallic photonic crystal through theoretical modeling and experimental measurements. An improved transfer matrix technique was developed to enable incorporation of complex dielectric function. Together with microscopic theory describing emitter radiative and non-radiative relaxation dynamics, a non-equilibrium thermal emission model is developed. Finally, experimental methodology was developed to measure absolute emissivity of photonic crystal at high temperatures with accuracy of +/-2%. Accurate emissivity measurements allow us to validate the procedure to treat the effect of the photonic crystal substrate.

  8. Crystal fingerprint space--a novel paradigm for studying crystal-structure sets.

    Science.gov (United States)

    Valle, Mario; Oganov, Artem R

    2010-09-01

    The initial aim of the crystal fingerprint project was to solve a very specific problem: to classify and remove duplicate crystal structures from the results generated by the evolutionary crystal-structure predictor USPEX. These duplications decrease the genetic diversity of the population used by the evolutionary algorithm, potentially leading to stagnation and, after a certain time, reducing the likelihood of predicting essentially new structures. After solving the initial problem, the approach led to unexpected discoveries: unforeseen correlations, useful derived quantities and insight into the structure of the overall set of results. All of these were facilitated by the project's underlying idea: to transform the structure sets from the physical configuration space to an abstract, high-dimensional space called the fingerprint space. Here every structure is represented as a point whose coordinates (fingerprint) are computed from the crystal structure. Then the space's distance measure, interpreted as structure 'closeness', enables grouping of structures into similarity classes. This model provides much flexibility and facilitates access to knowledge and algorithms from fields outside crystallography, e.g. pattern recognition and data mining. The current usage of the fingerprint-space model is revealing interesting properties that relate to chemical and crystallographic attributes of a structure set. For this reason, the mapping of structure sets to fingerprint space could become a new paradigm for studying crystal-structure ensembles and global chemical features of the energy landscape.

  9. Di-μ-acetato-μ-aqua-bis-[acetatobis(1H-benzimidazole)cobalt(II)].

    Science.gov (United States)

    Zimmermann, Iwan; Keene, Tony D; Neels, Antonia; Decurtins, Silvio

    2008-05-30

    In the title compound, [Co(2)(C(2)H(3)O(2))(4)(C(7)H(6)N(2))(4)(H(2)O)], the half-mol-ecule in the asymmetric unit is completed by a crystallographic twofold rotation axis to give the full mol-ecule. The Co(II) ions are approximately octahedrally coordinated with a cis-N(2)O(4) coordination sphere. The compound features intra-molecular O-H⋯O hydrogen bonds between the non-bridging acetate groups and the bridging water mol-ecule, and inter-molecular N-H⋯O hydrogen bonds between the acetates and amine H atoms of the benzimidazoles which determine the mol-ecular packing in the crystal structure.

  10. Nanoconfinement-Induced Structures in Chiral Liquid Crystals

    OpenAIRE

    2013-01-01

    We employ Monte Carlo simulations in a specialized isothermal-isobaric and in the grand canonical ensemble to study structure formation in chiral liquid crystals as a function of molecular chirality. Our model potential consists of a simple Lennard-Jones potential, where the attractive contribution has been modified to represent the orientation dependence of the interaction between a pair of chiral liquid-crystal molecules. The liquid crystal is confined between a pair of planar and atomicall...

  11. Crystal structure and characterization of pyrroloquinoline quinone disodium trihydrate

    Directory of Open Access Journals (Sweden)

    Ikemoto Kazuto

    2012-06-01

    Full Text Available Abstract Background Pyrroloquinoline quinone (PQQ, a tricarboxylic acid, has attracted attention as a growth factor, and its application to supplements and cosmetics is underway. The product used for these purposes is a water-soluble salt of PQQ disodium. Although in the past, PQQ disodiumpentahydrates with a high water concentration were used, currently, low hydration crystals of PQQ disodiumpentahydrates are preferred. Results We prepared a crystal of PQQ disodium trihydrate in a solution of ethanol and water, studied its structure, and analyzed its properties. In the prepared crystal, the sodium atom interacted with the oxygen atom of two carboxylic acids as well as two quinones of the PQQ disodium trihydrate. In addition, the hydration water of the prepared crystal was less than that of the conventional PQQ disodium crystal. From the results of this study, it was found that the color and the near-infrared (NIR spectrum of the prepared crystal changed depending on the water content in the dried samples. Conclusions The water content in the dried samples was restored to that in the trihydrate crystal by placing the samples in a humid environment. In addition, the results of X-ray diffraction (XRD and X-ray diffraction-differential calorimetry (XRD-DSC analyses show that the phase of the trihydrate crystal changed when the crystallization water was eliminated. The dried crystal has two crystalline forms that are restored to the original trihydrate crystals in 20% relative humidity (RH. This crystalline (PQQ disodium trihydrate is stable under normal environment.

  12. Clarithromycin monohydrate: a synchrotron X-ray powder study.

    Science.gov (United States)

    Noguchi, Shuji; Fujiki, Sadahiro; Iwao, Yasunori; Miura, Keiko; Itai, Shigeru

    2012-03-01

    In the crystal structure of the title compound, clarithromycin (CAM) monohydrate, C(38)H(69)NO(13)·H(2)O, the water mol-ecule behaves as a proton donor and is hydrogen bonded to the hy-droxy O atom of the CAM cladinose ring. The hy-droxy O atom also behaves as a proton donor, forming an inter-molecular hydrogen bond with one of the hy-droxy groups of the 14-membered aglycone ring. The CAM mol-ecules are linked through these hydrogen bonds into chains running parallel to the c axis.

  13. catena-Poly[[aqua-(ethyl anilinophospho-nato-κO)sodium(I)]-di-μ-aqua].

    Science.gov (United States)

    Fu, Zhiyong; Bai, Shuqiong

    2008-08-13

    In the title compound, [Na(C(8)H(11)NO(3)P)(H(2)O)(3)](n), the sodium cation is octa-hedrally coordinated by five water mol-ecules and one O-bonded ethyl anilinophospho-nate anion. Four of the water mol-ecules bridge to adjacent sodium ions, resulting in an infinite chain of edge-sharing NaO(6) polyhedra. A network of N-H⋯O and O-H⋯O hydrogen bonds helps to stabilize the crystal structure.

  14. Structure and Properties of Liquid Crystals

    CERN Document Server

    Blinov, Lev M

    2011-01-01

    This book by Lev M. Blinov is ideal to guide researchers from their very first encounter with liquid crystals to the level where they can perform independent experiments on liquid crystals with a thorough understanding of their behaviour also in relation to the theoretical framework. Liquid crystals can be found everywhere around us. They are used in virtually every display device, whether it is for domestic appliances of for specialized technological instruments. Their finely tunable optical properties make them suitable also for thermo-sensing and laser technologies. There are many monographs written by prominent scholars on the subject of liquid crystals. The majority of them presents the subject in great depth, sometimes focusing on a particular research aspect, and in general they require a significant level of prior knowledge. In contrast, this books aims at an audience of advanced undergraduate and graduate students in physics, chemistry and materials science. The book consists of three parts: the firs...

  15. The crystal structure of some rhenium and technetium dichalcogenides

    NARCIS (Netherlands)

    Lamfers, H.J; Meetsma, A.; Wiegers, G.A; deBoer, J.L.

    1996-01-01

    The crystal structures of ReSe2,ReS2, ReSSe and TcS2 are determined using single crystal X-ray diffraction. The compounds are triclinic with space group P (1) over bar. ReSe2, Res(2) and ReSSe have a distorted CdCl2-type structure; TcS2 has a distorted Cd(OH)(2)-type structure. In the case of Res,

  16. Photonic Crystal Structures with Tunable Structure Color as Colorimetric Sensors

    Directory of Open Access Journals (Sweden)

    Ke-Qin Zhang

    2013-03-01

    Full Text Available Colorimetric sensing, which transduces environmental changes into visible color changes, provides a simple yet powerful detection mechanism that is well-suited to the development of low-cost and low-power sensors. A new approach in colorimetric sensing exploits the structural color of photonic crystals (PCs to create environmentally-influenced color-changeable materials. PCs are composed of periodic dielectrics or metallo-dielectric nanostructures that affect the propagation of electromagnetic waves (EM by defining the allowed and forbidden photonic bands. Simultaneously, an amazing variety of naturally occurring biological systems exhibit iridescent color due to the presence of PC structures throughout multi-dimensional space. In particular, some kinds of the structural colors in living organisms can be reversibly changed in reaction to external stimuli. Based on the lessons learned from natural photonic structures, some specific examples of PCs-based colorimetric sensors are presented in detail to demonstrate their unprecedented potential in practical applications, such as the detections of temperature, pH, ionic species, solvents, vapor, humidity, pressure and biomolecules. The combination of the nanofabrication technique, useful design methodologies inspired by biological systems and colorimetric sensing will lead to substantial developments in low-cost, miniaturized and widely deployable optical sensors.

  17. Studies on growth, crystal structure and characterization of novel organic nicotinium trifluoroacetate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dhanaraj, P.V. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Rajesh, N.P., E-mail: rajeshnp@hotmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Sundar, J. Kalyana; Natarajan, S. [Department of Physics, Madurai Kamaraj University, Madurai 625 021 (India); Vinitha, G. [Department of Physics, Crescent Engineering College, Chennai 600 048 (India)

    2011-09-15

    Highlights: {yields} Good quality crystals of nicotinium trifluoroacetate in monoclinic system were grown for first time. {yields} Nicotinium trifluoroacetate crystal exhibits third order nonlinear optical properties. {yields} The optical spectrum of nicotinium trifluoroacetate crystal reveals the wide transmission in the entire range with cutoff wavelength at 286 nm. {yields} Nicotinium trifluoroacetate is a low dielectric constant material. - Abstract: An organic material, nicotinium trifluoroacetate (NTF) was synthesized and single crystals in monoclinic system were grown from aqueous solution for the first time. Its solubility and metastable zone width were estimated. The crystal structure of NTF was analyzed to reveal the molecular arrangements and the formation of hydrogen bonds in the crystal. High-resolution X-ray diffraction rocking curve measurements were performed to analyze the structural perfection of the grown crystals. Functional groups in NTF were identified by Fourier transform infrared spectral analysis. Thermal behaviour and stability of NTF were studied by thermogravimetric and differential thermal analysis and differential scanning calorimetry. Mechanical and dielectric properties of NTF crystals were analyzed. Optical studies reveal that NTF crystals are transparent in the wavelength range 286-1100 nm. The third order nonlinear optical parameters of NTF were derived by the Z-scan technique.

  18. Crystal structure of hexa-aqua-nickel(II) bis{2-[(5,6-di-hy-droxy-3-sul-fon-ato-quino-lin-1-ium-7-yl)oxy]acetate} dihydrate.

    Science.gov (United States)

    Le Thi Hong, Hai; Nguyen Thi Ngoc, Vinh; Tran Thi, Da; Nguyen Bich, Ngan; Van Meervelt, Luc

    2015-09-01

    The asymmetric unit of the title compound, [Ni(H2O)6](C11H8NO8S)2·2H2O, features a half-hexa-aqua-nickel(II) complex cation with the Ni(II) ion on an inversion center, one deprotonated 5,6-dihy-droxy-3-sulfoquinolin-7-yloxyacetic acid (QOH) molecule appearing in its zwitterionic form and one lattice water mol-ecule. The sulfonate group is disordered over two positions with occupancy factors of 0.655 (5) and 0.345 (5). The hexa-aqua-nickel(II) cation inter-acts through hydrogen bonding with eight QOH mol-ecules and two water mol-ecules. The six-membered rings of quinoline show π-π stacking [centroid-to-centroid distances of 3.679 (2) Å and 3.714 (2) Å].

  19. Functional substitution of coordination polyhedron in crystal structure of silicates

    Institute of Scientific and Technical Information of China (English)

    叶大年; 马哲生; 赫伟; 李哲; 施倪承; D.Pushcharovsky

    2002-01-01

    On the bases of the study of comparative crystal chemistry of silicates it has been concluded that the octahedra and square pyramids of Ti-0 and Zr-O play functional role of tetrahedra of Si-O in the construction of crystal structures. Therefore, those silicates may be named titano-and zircono-silicates. Because of the functional similarity of coordination polyhedra, the structures of cristobalite and feldspar have been compared with those of perovskite and garnet, respectively. As a new concept, the functional replacement of tetrahedra by octahedra and/or pyramids is defined by the authors of this paper for favorable comparison of relative crystal structures.

  20. Optically induced structural phase transitions in ion Coulomb crystals

    DEFF Research Database (Denmark)

    Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    , such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...

  1. X-Ray structural investigation of VAS-393 crystals

    CERN Document Server

    Martirosian, A H; Harurtjunian, V S

    2001-01-01

    X-ray structural study of VAS-393 crystals was performed. Investigations were carried out with the use of the Weissenberg rotating and powder (employing the Bjornstrem diagrams) methods. The lattice constants ''c'' and ''a''are calculated. The crystal is shown to belong to the trigonal syngony (medium category)

  2. Missing strings of residues in protein crystal structures.

    Science.gov (United States)

    Djinovic-Carugo, Kristina; Carugo, Oliviero

    2015-01-01

    A large fraction of the protein crystal structures deposited in the Protein Data Bank are incomplete, since the position of one or more residues is not reported, despite these residues are part of the material that was analyzed. This may bias the use of the protein crystal structures by molecular biologists. Here we observe that in the large majority of the protein crystal structures strings of residues are missing. Polar residues incline to occur in missing strings together with glycine, while apolar and aromatic residues tend to avoid them. Particularly flexible residues, as shown by their extremely high B-factors, by their exposure to the solvent and by their secondary structures, flank the missing strings. These data should be a helpful guideline for crystallographers that encounter regions of flat and uninterpretable electron density as well as end-users of crystal structures.

  3. Growth morphology and structural characteristic of C70single crystals

    Institute of Scientific and Technical Information of China (English)

    周维亚; 解思深; 吴源; 常保和; 王刚; 钱露茜

    1999-01-01

    Large size C70 single crystals with the dimension of more than 5 mm are grown from the vapor phase by controlling nucleation. X-ray diffraction and electron diffraction confirm that in the C70 single crystal a phase of the hexagonal close-packed (hcp) structure coexists with a minor face-center-cubic (fcc) phase at room temperature. The morphologies and their formation mechanism of the C70 single crystals are investigated by means of scanning electron microscopy and optical microscopy. The influence of growth conditions on the morphologies of C70 single crystals is discussed.

  4. Structural and mechanical studies of cadmium manganese thiocyanate crystal

    Science.gov (United States)

    Manikandan, M. R.; Vijayaprasath, G.; babu, G. Anandha; Bhagavannarayan, G.; Vijayan, N.; Ravi, G.

    2012-06-01

    Single crystals of cadmium manganese thiocyanate (CMTC) have been synthesized successfully and grown by slow evaporation method. The structural perfection of the grown crystals has been analyzed by High resolution X-ray diffraction (HRXRD), which shows the crystalline perfection of the grown crystal is quite good. Optical behavior was assessed by UV-Vis analysis and found that no absorption in the UV visible region and it may be useful for second harmonic applications. The mechanical hardness of the grown crystals was studied and Vicker's microhardness, Stiffness constant was calculated.

  5. Construction of crystal structure prototype database: methods and applications.

    Science.gov (United States)

    Su, Chuanxun; Lv, Jian; Li, Quan; Wang, Hui; Zhang, Lijun; Wang, Yanchao; Ma, Yanming

    2017-04-26

    Crystal structure prototype data have become a useful source of information for materials discovery in the fields of crystallography, chemistry, physics, and materials science. This work reports the development of a robust and efficient method for assessing the similarity of structures on the basis of their interatomic distances. Using this method, we proposed a simple and unambiguous definition of crystal structure prototype based on hierarchical clustering theory, and constructed the crystal structure prototype database (CSPD) by filtering the known crystallographic structures in a database. With similar method, a program structure prototype analysis package (SPAP) was developed to remove similar structures in CALYPSO prediction results and extract predicted low energy structures for a separate theoretical structure database. A series of statistics describing the distribution of crystal structure prototypes in the CSPD was compiled to provide an important insight for structure prediction and high-throughput calculations. Illustrative examples of the application of the proposed database are given, including the generation of initial structures for structure prediction and determination of the prototype structure in databases. These examples demonstrate the CSPD to be a generally applicable and useful tool for materials discovery.

  6. Construction of crystal structure prototype database: methods and applications

    Science.gov (United States)

    Su, Chuanxun; Lv, Jian; Li, Quan; Wang, Hui; Zhang, Lijun; Wang, Yanchao; Ma, Yanming

    2017-04-01

    Crystal structure prototype data have become a useful source of information for materials discovery in the fields of crystallography, chemistry, physics, and materials science. This work reports the development of a robust and efficient method for assessing the similarity of structures on the basis of their interatomic distances. Using this method, we proposed a simple and unambiguous definition of crystal structure prototype based on hierarchical clustering theory, and constructed the crystal structure prototype database (CSPD) by filtering the known crystallographic structures in a database. With similar method, a program structure prototype analysis package (SPAP) was developed to remove similar structures in CALYPSO prediction results and extract predicted low energy structures for a separate theoretical structure database. A series of statistics describing the distribution of crystal structure prototypes in the CSPD was compiled to provide an important insight for structure prediction and high-throughput calculations. Illustrative examples of the application of the proposed database are given, including the generation of initial structures for structure prediction and determination of the prototype structure in databases. These examples demonstrate the CSPD to be a generally applicable and useful tool for materials discovery.

  7. Molecular and Crystal Structures of Three Berberine Derivatives

    OpenAIRE

    Jiří Dostál; Zdirad Žák; Marek NeÄÂas; Milan PotáÄÂek; Stanislav Man

    2001-01-01

    Berberine azide, berberine thiocyanate, and 8-cyano-8H-berberine were prepared from berberine chloride, a quaternary protoberberine alkaloid. The molecular and crystal structures of all compounds are reported and discussed.

  8. Determination of channeling perspectives for complex crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Allen, W.R.

    1993-03-01

    Specification of the atomic arrangement for axes and planes of high symmetry is essential for crystal alignment using Rutherford backscattering and for studies of the lattice location of impurities in single crystals. By rotation of an inscribed orthogonal coordinate system, a visual image for a given perspective of a crystal structure can be specified. Knowledge of the atomic arrangement permits qualitative channeling perspectives to be visualized and calculation of continuum potentials for channeling. Channeling angular-yield profiles can then be analytically modeled and, subsequently, shadowing by host atoms of positions within the unit cell predicted. Software to calculate transformed atom positions for a channeling perspective in a single crystal are described and illustrated for the spinel crystal structure.

  9. Crystal structure of the new hybrid material bis-(1,4-diazo-niabi-cyclo-[2.2.2]octa-ne) di-μ-chlorido-bis-[tetra-chlorido-bis-muthate(III)] dihydrate.

    Science.gov (United States)

    Chouri, Marwen; Boughzala, Habib

    2015-11-01

    The title compound bis-(1,4-diazo-niabi-cyclo-[2.2.2]octa-ne) di-μ-chlorido-bis-[tetra-chlorido-bis-muthate(III)] dihydrate, (C6H14N2)2[Bi2Cl10]·2H2O, was ob-tain-ed by slow evaporation at room temperature of a hydro-chloric aqueous solution (pH = 1) containing bis-muth(III) nitrate and 1,4-di-aza-bicyclo-[2.2.2]octane (DABCO) in a 1:2 molar ratio. The structure displays a two-dimensional arrangement parallel to (100) of isolated [Bi2Cl10](4-) bi-octa-hedra (site symmetry -1) separated by layers of organic 1,4-diazo-niabi-cyclo-[2.2.2]octane dications [(DABCOH2)(2+)] and water mol-ecules. O-H⋯Cl, N-H⋯O and N-H⋯Cl hydrogen bonds lead to additional cohesion of the structure.

  10. Improving nanocavity switching using Fano resonances in photonic crystal structures

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Kristensen, Philip Trøst; Elesin, Yuriy;

    2013-01-01

    We present a simple design for achieving Fano resonances in photonic crystal coupled waveguide-cavity structures. A coupled mode theory analysis shows an order of magnitude reduction in switching energy compared to conventional Lorentz resonances.......We present a simple design for achieving Fano resonances in photonic crystal coupled waveguide-cavity structures. A coupled mode theory analysis shows an order of magnitude reduction in switching energy compared to conventional Lorentz resonances....

  11. Crystal structure of S-(4-methylbenzyl piperidinedithiocarbamate

    Directory of Open Access Journals (Sweden)

    Z. A. Rahima

    2015-09-01

    Full Text Available The title compound, C14H19NS2, crystallizes in the thione form with the presence of a C=S bond. The piperidine ring adopts a chair conformation. The dihedral angle between the essentially planar dithiocarbamate and p-tolyl fragments is 74.46 (10°

  12. Allophycocyanin and phycocyanin crystal structures reveal facets of phycobilisome assembly.

    Science.gov (United States)

    Marx, Ailie; Adir, Noam

    2013-03-01

    X-ray crystal structures of the isolated phycobiliprotein components of the phycobilisome have provided high resolution details to the description of this light harvesting complex at different levels of complexity and detail. The linker-independent assembly of trimers into hexamers in crystal lattices of previously determined structures has been observed in almost all of the phycocyanin (PC) and allophycocyanin (APC) structures available in the Protein Data Bank. In this paper we describe the X-ray crystal structures of PC and APC from Synechococcus elongatus sp. PCC 7942, PC from Synechocystis sp. PCC 6803 and PC from Thermosynechococcus vulcanus crystallized in the presence of urea. All five structures are highly similar to other PC and APC structures on the levels of subunits, monomers and trimers. The Synechococcus APC forms a unique loose hexamer that may show the structural requirements for core assembly and rod attachment. While the Synechococcus PC assembles into the canonical hexamer, it does not further assemble into rods. Unlike most PC structures, the Synechocystis PC fails to form hexamers. Addition of low concentrations of urea to T. vulcanus PC inhibits this proteins propensity to form hexamers, resulting in a crystal lattice composed of trimers. The molecular source of these differences in assembly and their relevance to the phycobilisome structure is discussed.

  13. 3-Acetyl-1-(2,3-dichloro-phen-yl)thio-urea.

    Science.gov (United States)

    Gowda, B Thimme; Foro, Sabine; Kumar, Sharatha

    2012-08-01

    In the crystal structure of the title compound, C(9)H(8)Cl(2)N(2)OS, there are two mol-ecules in the asymmetric unit which are connected by a pair of N-H⋯S hydrogen bonds. An intra-molecular N-H⋯O hydrogen bond stabilizes the mol-ecular conformation of each molecule.

  14. Icosahedral symmetry described by an incommensurately modulated crystal structure model

    DEFF Research Database (Denmark)

    Wolny, Janusz; Lebech, Bente

    1986-01-01

    A crystal structure model of an incommensurately modulated structure is presented. Although six different reciprocal vectors are used to describe the model, all calculations are done in three dimensions making calculation of the real-space structure trivial. Using this model, it is shown that both...

  15. Homodiselenacalix[4]arenes: Molecules with Unique Channelled Crystal Structures.

    Science.gov (United States)

    Thomas, Joice; Dobrzańska, Liliana; Van Meervelt, Luc; Quevedo, Mario Alfredo; Woźniak, Krzysztof; Stachowicz, Marcin; Smet, Mario; Maes, Wouter; Dehaen, Wim

    2016-01-18

    A synthetic route towards homodiselenacalix[4]arene macrocycles is presented, based on the dynamic covalent chemistry of diselenides. The calixarene inner rim is decorated with either alkoxy or tert-butyl ester groups. Single-crystal X-ray analysis of two THF solvates with methoxy and ethoxy substituents reveals the high similarity of their molecular structures and alterations on the supramolecular level. In both crystal structures, solvent channels are present and differ in both shape and capacity. Furthermore, the methoxy-substituted macrocycle undergoes a single-crystal-to-single-crystal transformation during which the molecular structure changes its conformation from 1,3-alternate (loaded with THF/water) to 1,2-alternate (apohost form). Molecular modelling techniques were applied to explore the conformational and energetic behaviour of the macrocycles.

  16. Chiral Liquid Crystals: Structures, Phases, Effects

    Directory of Open Access Journals (Sweden)

    Ingo Dierking

    2014-06-01

    Full Text Available The introduction of chirality, i.e., the lack of mirror symmetry, has a profound effect on liquid crystals, not only on the molecular scale but also on the supermolecular scale and phase. I review these effects, which are related to the formation of supermolecular helicity, the occurrence of novel thermodynamic phases, as well as electro-optic effects which can only be observed in chiral liquid crystalline materials. In particular, I will discuss the formation of helical superstructures in cholesteric, Twist Grain Boundary and ferroelectric phases. As examples for the occurrence of novel phases the Blue Phases and Twist Grain Boundary phases are introduced. Chirality related effects are demonstrated through the occurrence of ferroelectricity in both thermotropic as well as lyotropic liquid crystals. Lack of mirror symmetry is also discussed briefly for some biopolymers such as cellulose and DNA, together with its influence on liquid crystalline behavior.

  17. Synthesis and Crystal Structure of a New Manganese Complex

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; LIU Ping; CHEN Yun

    2003-01-01

    @@ In order to study the relationship between the manganese ion and the biological coordination agent, the role ofmanganese ion in the active sites and the structure of the active sites in the manganese enzymes, small molecule complexes are often applied to modeling the structure and the properties of reaction in the active centers. In this pa per, we will report the synthesis and crystal structure of a new manganese(Ⅱ) complex, catena[ aqua-(p-methoxybenzoato- O, O′ ) - (p-methoxybenzoato- O )- (2,2′-bipyridine)-manganese (Ⅱ) ] (p-methoxybenzoic acid). The crystal structure was confirmeded by X-ray crystallography analysis.

  18. Anisotropic crystal structure of magnetized neutron star crust

    Science.gov (United States)

    Baiko, D. A.; Kozhberov, A. A.

    2017-09-01

    Although crystallized neutron star crust is responsible for many fascinating observational phenomena, its actual microscopic structure in tremendous gravitational and magnetic fields is not understood. Here we show that in a non-uniform magnetic field, three-dimensional ionic Coulomb crystals comprising the crust may stretch or shrink while their electrostatic pressure becomes anisotropic. The pressure depends non-linearly on the magnitude of the stretch, so that a continuous magnetic field evolution may result in an abrupt crystal elongation or contraction. This may provide a trigger for magnetar activity. A phonon mode instability is revealed, which sets the limits of magnetic field variation beyond which the crystal is destroyed. These limits sometimes correspond to surprisingly large deformations. It is not known what happens to crust matter subject to a pressure anisotropy exceeding these limits. We hypothesize that the ion system then possesses a long-range order only in one or two dimensions, that is becomes a liquid crystal.

  19. Structure of initial crystals formed during human amelogenesis

    Science.gov (United States)

    Cuisinier, F. J. G.; Voegel, J. C.; Yacaman, J.; Frank, R. M.

    1992-02-01

    X-ray diffraction analysis revealed only the existence of carbonated hydroxyapatite (c.HA) during amelogenesis, whereas conventional transmission electron microscopy investigations showed that developing enamel crystals have a ribbon-like habit. The described compositional changes could be an indication for the presence of minerals different from c.HA. However, the absence of identification of such a mineral shows the need of studies by high resolution electron microscopy (HREM) of initial formed human enamel crystals. We demonstrate the existence of two crystal families involved in the early stages of biomineralization: (a) nanometer-size particles which appeared as a precursor phase; (b) ribbon-like crystals, with a structure closely related to c.HA, which by a progressive thickening process tend to attain the mature enamel crystal habit.

  20. Single-Crystal Structure of a Covalent Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, YB; Su, J; Furukawa, H; Yun, YF; Gandara, F; Duong, A; Zou, XD; Yaghi, OM

    2013-11-06

    The crystal structure of a new covalent organic framework, termed COF-320, is determined by single-crystal 3D electron diffraction using the rotation electron diffraction (RED) method for data collection. The COF crystals are prepared by an imine condensation of tetra-(4-anilyl)methane and 4,4'-biphenyldialdehyde in 1,4-dioxane at 120 degrees C to produce a highly porous 9-fold interwoven diamond net. COF-320 exhibits permanent porosity with a Langmuir surface area of 2400 m(2)/g and a methane total uptake of 15.0 wt % (176 cm(3)/cm(3)) at 25 degrees C and 80 bar. The successful determination of the structure of COF-320 directly from single-crystal samples is an important advance in the development of COF chemistry.

  1. Crystal structure of 4-(4-methoxyphenoxybenzaldehyde

    Directory of Open Access Journals (Sweden)

    Andreas Schäfer

    2015-12-01

    Full Text Available The title compound, C14H12O3, was synthesized via the nucleophilic addition of 4-methoxyphenol to 4-fluorobenzaldehyde. The dihedral angle between the least-squares planes of the benzene rings is 71.52 (3° and the C—O—C angle at the central O atom is 118.82 (8°. In the crystal, weak C—H...O hydrogen bonds link the molecules to generate supramolecular layers in the bc plane. The layers are linked by weak C—H...π interactions.

  2. The different conformations and crystal structures of dihydroergocristine

    Science.gov (United States)

    Mönch, B.; Kraus, W.; Köppen, R.; Emmerling, F.

    2016-02-01

    The identification of different forms of dihydroergocristine (DHEC) was carried out by crystallization from different organic solvents. DHEC was identified as potential template for molecularly imprinted polymers (MIPs) for the epimeric specific analysis of ergot alkaloids (EAs) in food. DHEC was crystallized from different solvents in order to mimic the typical MIP synthesis conditions. Four new solvatomorphs of DHEC were obtained. All solvatomorphs contain a water molecule in the crystal structure, whereas three compounds contain an additional solvent molecule. Based on the conformation of DHEC a comparison with typical EA molecules was possible. The analysis showed that DHEC is a suitable template for MIPs for EAs.

  3. Crystal structure of ethyl 2,4-dichloroquinoline-3-carboxylate

    Directory of Open Access Journals (Sweden)

    Alberto Cabrera

    2015-12-01

    Full Text Available In the crystal structure of the title compound, C12H9Cl2NO2, the mean planes through the quinoline and carboxylate groups have r.m.s. deviations of 0.006 and 0.021 Å, respectively, and form a dihedral angle of 87.06 (19°. In the crystal, molecules are linked via very weak C—H...O hydrogen bonds, forming chains, which propagate along the c-axis direction.

  4. Band structures and localization properties of aperiodic layered phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yan Zhizhong, E-mail: zzyan@bit.edu.cn [Department of Applied Mathematics, Beijing Institute of Technology, Beijing 100081 (China); Zhang Chuanzeng [Department of Civil Engineering, University of Siegen, D-57078 Siegen (Germany)

    2012-03-15

    The band structures and localization properties of in-plane elastic waves with coupling of longitudinal and transverse modes oblique propagating in aperiodic phononic crystals based on Thue-Morse and Rudin-Shapiro sequences are studied. Using transfer matrix method, the concept of the localization factor is introduced and the correctness is testified through the Rytov dispersion relation. For comparison, the perfect periodic structure and the quasi-periodic Fibonacci system are also considered. In addition, the influences of the random disorder, local resonance, translational and/or mirror symmetries on the band structures of the aperiodic phononic crystals are analyzed in this paper.

  5. Band structures and localization properties of aperiodic layered phononic crystals

    Science.gov (United States)

    Yan, Zhi-Zhong; Zhang, Chuanzeng

    2012-03-01

    The band structures and localization properties of in-plane elastic waves with coupling of longitudinal and transverse modes oblique propagating in aperiodic phononic crystals based on Thue-Morse and Rudin-Shapiro sequences are studied. Using transfer matrix method, the concept of the localization factor is introduced and the correctness is testified through the Rytov dispersion relation. For comparison, the perfect periodic structure and the quasi-periodic Fibonacci system are also considered. In addition, the influences of the random disorder, local resonance, translational and/or mirror symmetries on the band structures of the aperiodic phononic crystals are analyzed in this paper.

  6. Protein dynamics derived from clusters of crystal structures.

    OpenAIRE

    van Aalten, D M; Conn, D A; de Groot, B L; Berendsen, H J; Findlay, J B; Amadei, A

    1997-01-01

    A method is presented to mathematically extract concerted structural transitions in proteins from collections of crystal structures. The "essential dynamics" procedure is used to filter out small-amplitude fluctuations from such a set of structures; the remaining large conformational changes describe motions such as those important for the uptake/release of substrate/ligand and in catalytic reactions. The method is applied to sets of x-ray structures for a number of proteins, and the results ...

  7. Crystal Structure of the Vanadate-Inhibited Ca2+-ATPase

    DEFF Research Database (Denmark)

    Clausen, Johannes D.; Bublitz, Maike; Arnou, Bertrand Jean-Paul;

    2016-01-01

    Vanadate is the hallmark inhibitor of the P-type ATPase family; however, structural details of its inhibitory mechanism have remained unresolved. We have determined the crystal structure of sarcoplasmic reticulum Ca2+-ATPase with bound vanadate in the absence of Ca2+. Vanadate is bound...

  8. Optimization of liquid crystal structures for real time holography applications.

    Science.gov (United States)

    Sahraoui, B; Anczykowska, A; Bartkiewicz, S; Mysliwiec, J

    2011-11-21

    In this paper we present results of experiments designed to increase our understanding of the photorefractive effect occurring during processes of dynamic hologram generation in Hybrid Photorefractive Liquid Crystal Structures (HPLCS). We also propose equivalent mathematical model which can be used to optimize those structures in order to obtain the highest diffraction efficiency in possibly shortest time.

  9. Heterogeneous Crystallization on Pairs of Pre-Structured Seeds.

    Science.gov (United States)

    Jungblut, Swetlana; Dellago, Christoph

    2016-09-01

    Studying the effects of small pre-structured seeds on the crystallization transition in an undercooled monodisperse Lennard-Jones fluid with transition interface path sampling combined with molecular dynamics simulations, we analyze the impact of the simultaneous presence of two seeds with various structures. In the presence of seeds with face- and body-centered cubic structures, we find that decreasing the seed-to-seed distance enhances the probability of the crystalline clusters formed on one of the seeds to grow beyond the critical size, thus, increasing the crystal nucleation rates. In contrast, when seeds have an icosahedral structure, the crystalline clusters form mostly in the bulk. The crystal nucleation rate, however, is also determined by the distance between the seeds with regular structure in which the lattice spacing is equal to the bulk lattice constant, pointing to a heterogeneous crystal nucleation that occurs away from the icosahedrally structured seeds. For slightly squeezed seeds, the effects of the presence of seeds with face- and body-centered cubic structures are reduced in comparison to the regular seeds, and we do not see any effect of the presence of the second seed for seeds with squeezed icosahedral structure.

  10. Crystal structure of 1-(4-formylbenzylidenethiosemicarbazone

    Directory of Open Access Journals (Sweden)

    Rosa Carballo

    2014-09-01

    Full Text Available The asymmetric unit of the title compound, C9H9N3OS, contains two approximately planar molecules (r.m.s. deviations for 14 non-H atoms = 0.094 and 0.045 Å, with different conformations. In one of them, the C=O group is syn to the S atom and in the other it is anti. Each molecule features an intramolecular N—H...N hydrogen bond, which generates an S(5 ring. In the crystal, molecules are linked by N—H...O and N—H...S hydrogen bonds, generating discrete networks; the syn molecules form [010] chains and the anti molecules form (100 sheets.

  11. Crystal structure of 4-methylsulfanyl-2-phenylquinazoline

    Directory of Open Access Journals (Sweden)

    Mohammed B. Alshammari

    2014-08-01

    Full Text Available In the title compound, C15H12N2S, the methylthioquinazoline group is planar with the methyl C displaced by only 0.116 (3 Å from the plane of the quinazoline moiety. The dihedral angle between the phenyl ring and the quinazoline ring system is 13.95 (5°. In the crystal, each molecule is linked by π–π stacking between to two adjacent inversion-related molecules. On one side, the inverted quinazoline groups interact with a centroid–centroid distance of 3.7105 (9 Å. On the other side, the quinazoline group interacts with the pyrimidine and phenyl rings of the second neighbour with centroid–centroid distances of 3.5287 (8 and 3.8601 (9 Å, respectively.

  12. Crystal structure of 1-bromo-2-(phenylselenylbenzene

    Directory of Open Access Journals (Sweden)

    Bronte J. Charette

    2015-03-01

    Full Text Available In the title compound, C12H9BrSe, the Se atom exhibits a bent geometry, with a C—Se—C bond angle of 99.19 (6°. The ortho Se and Br atoms are slightly displaced from opposite faces of the mean plane of the benzene ring [by 0.129 (2 and 0.052 (2 Å, respectively]. The planes of the benzene and phenyl rings form a dihedral angle of 72.69 (5°. In the crystal, π-stacking interactions between inversion-related phenyl rings are observed, with a centroid–centroid distance of 3.630 (1 Å.

  13. Crystal structure of 2-aminopyridinium 6-chloronicotinate

    Directory of Open Access Journals (Sweden)

    N. Jeeva Jasmine

    2015-09-01

    Full Text Available In the title salt, C5H7N+·C6H3ClNO−, the 2-aminopyridinium cation interacts with the carboxylate group of the 6-chloronicotinate anion through a pair of independent N—H...O hydrogen bonds, forming an R22(8 ring motif. In the crystal, these dimeric units are connected further via N—H...O hydrogen bonds, forming chains along [001]. In addition, weak C—H...N and C—H...O hydrogen bonds, together with weak π–π interactions, with centroid–centroid distances of 3.6560 (5 and 3.6295 (5 Å, connect the chains, forming a two-dimensional network parallel to (100.

  14. Structure and properties of MTiOXO sub 4 crystals

    CERN Document Server

    Latham, T J

    2000-01-01

    linked to chains of particular atoms along the three crystallographic axes. Dielectric measurements of a series of arsenate crystals and various doped phosphate crystals demonstrate that MTiOXO sub 4 isomorphs exhibit dielectric relaxation of a non-Debye type and appear to conform to the hopping charge-carrier and low frequency dispersion response models. A reduction in the ionic conductivity is observed in the arsenate crystals and phosphate crystals doped with trivalent ions. Arrhenius plots indicate that the activation energies of the mixed cation arsenate crystals are significantly higher than the other KTiOPO sub 4 isomorphs. This observation suggests that the modified oxygen framework in these mixed arsenate crystals contributes intrinsically to the large activation energies required for ionic conduction. This thesis is a study of the structural, optical and electrical properties of MTiOXO sub 4 crystals, where M is a monovalent cation such as K, Rb etc and X is P or As. Low and high-temperature single-...

  15. Functional substitution of coordination polyhedron in crystal structure of silicates

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    On the bases of the study of comparative crystal chemistry of silicates it has been concluded that the octahedra and square pyramids of Ti-O and Zr-O play functional role of tetrahedra of Si-O in the construction of crystal structures.Therefore,those silicates may be named titano- and zircono-silicates.Because of the functional similarity of coordination polyhedra,the structures of cristobalite and feldspar have been compared with those of perovskite and garnet,respectively.As a new concept,the functional replacement of tetrahedra by octahedra and/or pyramids is defined by the authors of this paper for favorable comparison of relative crystal structures.

  16. Electron Crystallographic Study on Structure Determination for Minute Crystals

    Institute of Scientific and Technical Information of China (English)

    LI Fanghua; FAN Haifu; WAN Zhenghua; HU Jianjun; TANG Dong

    2007-01-01

    @@ In the 1970s the development of high-resolution electron microscopy (HREM) provided a new approach to structure determination for minute crystals, which is thoroughly different from the diffraction methods.However, the previous method of trial and error has its own limits, such as some preliminary structural information must be known in advance; the crystals must be sufficient strong under the electron beam irradiation;and not all atoms can be seen in the image. Two ideas were proposed to initiate the present research project:one is to transform an arbitrary image into the crystal structure map, and the other is to enhance the image resolution by combining the information contained in the image and the corresponding electron diffraction pattern. These ideas have been realized via the combination of electron microscopy and diffraction crystallography.

  17. A crystal structure prediction enigma solved

    DEFF Research Database (Denmark)

    Hoser, Anna Agnieszka; Sovago, Ioana; Lanzac, A.

    2017-01-01

    The seemingly unpredictable structure of gallic acid monohydrate form IV has been investigated using accurate X-ray diffraction measurements at temperatures of 10 and 123 K. The measurements demonstrate that the structure is commensurately modulated at 10 K and disordered at higher temperatures. ...

  18. Solving Crystal Structures from Powder Diffraction Data

    DEFF Research Database (Denmark)

    Christensen, A. Nørlund; Lehmann, M. S.; Nielsen, Mogens

    1985-01-01

    High resolution powder data from both neutron and X-ray (synchrotron) sources have been used to estimate the possibility of direct structure determination from powder data. Two known structures were resolved by direct methods with neutron and X-ray data. With synchrotron X-ray data, the measured...... range of data was insufficient for a structure analysis, but the R-factor calculations showed the intensities extracted from the profile data to be of acceptable quality. The results were used to estimate the largest structure that might be solved using routine techniques. It was found that the limit...... would be near twenty atoms in the asymmetric part of a centro-symmetric structure....

  19. Crystal structure of aspartame anhydrate from powder diffraction data. Structural aspects of the dehydration process of aspartame

    NARCIS (Netherlands)

    Guguta, C.; Meekes, H.L.M.; Gelder, R. de

    2006-01-01

    Aspartame has three pseudo-polymorphic forms, two hydrates and a hemi-hydrate, for which crystal structures were determined from single-crystal diffraction data. This paper presents the crystal structure of the anhydrate, which was obtained by dehydrating the hemi-hydrate. The crystal structure of a

  20. Polymorph identification and crystal structure determination by a combined crystal structure prediction and transmission electron microscopy approach.

    Science.gov (United States)

    Eddleston, Mark D; Hejczyk, Katarzyna E; Bithell, Erica G; Day, Graeme M; Jones, William

    2013-06-10

    Electron diffraction offers advantages over X-ray based methods for crystal structure determination because it can be applied to sub-micron sized crystallites, and picogram quantities of material. For molecular organic species, however, crystal structure determination with electron diffraction is hindered by rapid crystal deterioration in the electron beam, limiting the amount of diffraction data that can be collected, and by the effect of dynamical scattering on reflection intensities. Automated electron diffraction tomography provides one possible solution. We demonstrate here, however, an alternative approach in which a set of putative crystal structures of the compound of interest is generated by crystal structure prediction methods and electron diffraction is used to determine which of these putative structures is experimentally observed. This approach enables the advantages of electron diffraction to be exploited, while avoiding the need to obtain large amounts of diffraction data or accurate reflection intensities. We demonstrate the application of the methodology to the pharmaceutical compounds paracetamol, scyllo-inositol and theophylline. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Crystal-Size-Dependent Structural Transitions in Nanoporous Crystals: Adsorption-Induced Transitions in ZIF-8

    KAUST Repository

    Zhang, Chen

    2014-09-04

    © 2014 American Chemical Society. Understanding the crystal-size dependence of both guest adsorption and structural transitions of nanoporous solids is crucial to the development of these materials. We find that nano-sized metal-organic framework (MOF) crystals have significantly different guest adsorption properties compared to the bulk material. A new methodology is developed to simulate the adsorption and transition behavior of entire MOF nanoparticles. Our simulations predict that the transition pressure significantly increases with decreasing particle size, in agreement with crystal-size-dependent experimental measurements of the N2-ZIF-8 system. We also propose a simple core-shell model to examine this effect on length scales that are inaccessible to simulations and again find good agreement with experiments. This study is the first to examine particle size effects on structural transitions in ZIFs and provides a thermodynamic framework for understanding the underlying mechanism.

  2. Photonic crystals, light manipulation, and imaging in complex nematic structures

    Science.gov (United States)

    Ravnik, Miha; Å timulak, Mitja; Mur, Urban; Čančula, Miha; Čopar, Simon; Žumer, Slobodan

    2016-03-01

    Three selected approaches for manipulation of light by complex nematic colloidal and non-colloidal structures are presented using different own custom developed theoretical and modelling approaches. Photonic crystals bands of distorted cholesteric liquid crystal helix and of nematic colloidal opals are presented, also revealing distinct photonic modes and density of states. Light propagation along half-integer nematic disclinations is shown with changes in the light polarization of various winding numbers. As third, simulated light transmission polarization micrographs of nematic torons are shown, offering a new insight into the complex structure characterization. Finally, this work is a contribution towards using complex soft matter in optics and photonics for advanced light manipulation.

  3. Synthesis, crystal structure and biological activity of novel diester cyclophanes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Yang, Bingqin; Fang, Xianwen; Cheng, Zhao; Yang, Meipan, E-mail: yangbq@nwu.edu.cn [Department of Chemistry, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Northwest University, Shaanxi (China)

    2012-10-15

    A series of novel diester cyclophanes was synthesized by esterification of 1,2-benzenedicarbonyl chloride with eight different diols under high dilution conditions. The structures of the compounds were verified by elemental analysis, {sup 1}H nuclear magnetic resonance (NMR), IR spectroscopy and high resolution mass spectrometry (HRMS). The crystal structures of two compounds were characterized by single crystal X-ray diffractometry (XRD). All the new cyclophanes were evaluated for biological activities and the results showed that some of these compounds have low antibacterial or antifungal activities (author)

  4. Synthesis and Crystal Structure of Metronidazole-derived Compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A MET-OH derivative, MET-OTs 1, was designed, prepared and structurally charac- terized by single-crystal X-ray diffraction. X-ray structure analysis reveals that 1 crystallizes in the monoclinic system, space group P21/c, with a = 16.1178(14), b = 7.5473(6), c = 13.4161(11) (A), V = 1520.3(2) (A)3, β = 111.3210(10)o, Z = 4, Dc = 1.421 g/cm3 and F(000) = 680.

  5. Fine structure of fields in 2D photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Volkov, V. S.; Bozhevolnyi, S. I.

    2006-01-01

    We resolve fine structure of fields in a single-row missing photonic crystal waveguide by finite-difference time-domain modelling and SNOM measurements. Both linear dispersion and slow-light regimes in proximity of the cutoff are addressed in the analysis.......We resolve fine structure of fields in a single-row missing photonic crystal waveguide by finite-difference time-domain modelling and SNOM measurements. Both linear dispersion and slow-light regimes in proximity of the cutoff are addressed in the analysis....

  6. Clathrate Structure Determination by Combining Crystal Structure Prediction with Computational and Experimental (129) Xe NMR Spectroscopy.

    Science.gov (United States)

    Selent, Marcin; Nyman, Jonas; Roukala, Juho; Ilczyszyn, Marek; Oilunkaniemi, Raija; Bygrave, Peter J; Laitinen, Risto; Jokisaari, Jukka; Day, Graeme M; Lantto, Perttu

    2017-01-23

    An approach is presented for the structure determination of clathrates using NMR spectroscopy of enclathrated xenon to select from a set of predicted crystal structures. Crystal structure prediction methods have been used to generate an ensemble of putative structures of o- and m-fluorophenol, whose previously unknown clathrate structures have been studied by (129) Xe NMR spectroscopy. The high sensitivity of the (129) Xe chemical shift tensor to the chemical environment and shape of the crystalline cavity makes it ideal as a probe for porous materials. The experimental powder NMR spectra can be used to directly confirm or reject hypothetical crystal structures generated by computational prediction, whose chemical shift tensors have been simulated using density functional theory. For each fluorophenol isomer one predicted crystal structure was found, whose measured and computed chemical shift tensors agree within experimental and computational error margins and these are thus proposed as the true fluorophenol xenon clathrate structures.

  7. High resolution crystal structure of human β-glucuronidase reveals structural basis of lysosome targeting

    National Research Council Canada - National Science Library

    Hassan, Md Imtaiyaz; Waheed, Abdul; Grubb, Jeffery H; Klei, Herbert E; Korolev, Sergey; Sly, William S

    2013-01-01

    ...). Here we report a high resolution crystal structure of human GUS at 1.7 Å resolution and present an extensive analysis of the structural features, unifying recent findings in the field of lysosome targeting and glycosyl hydrolases...

  8. High Resolution Crystal Structure of Human [beta]-Glucuronidase Reveals Structural Basis of Lysosome Targeting

    National Research Council Canada - National Science Library

    Hassan, Md; Waheed, Abdul; Grubb, Jeffery; Klei, Herbert; Korolev, Sergey; Sly, William

    2013-01-01

    ...). Here we report a high resolution crystal structure of human GUS at 1.7 Å resolution and present an extensive analysis of the structural features, unifying recent findings in the field of lysosome targeting and glycosyl hydrolases...

  9. Synthesis, crystal structure, crystal growth and physical properties of N,N-diethyl anilinium picrate

    Science.gov (United States)

    Subramaniyan @ Raja, R.; Anandha Babu, G.; Ramasamy, P.

    2011-11-01

    Crystalline substance of N,N-diethyl anilinium picrate (NNDEAP) has been synthesized and single crystals of NNDEAP were successfully grown for the first time by the slow evaporation solution growth technique at room temperature with dimensions 14×10×10 mm3. The formation of the new crystal has been confirmed by single crystal X-ray diffraction studies. The structural perfection of the grown crystal was analyzed by high resolution X-ray diffraction (HRXRD) measurements. The functional groups of NNDEAP have been identified by Fourier transform infrared spectral studies. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have also been carried out and the thermal behavior of NNDEAP has been studied. The UV-vis-NIR studies have been carried out to identify the optical transmittance and the cut off wavelength of NNDEAP is identified. The dielectric loss and the dielectric constant as a function of frequency and temperature were measured for the grown crystal and the nature of variation of dielectric constant εr and dielectric losses (tan δ) were studied. Vicker's hardness test has been carried out on NNDEAP to measure the load dependent hardness. The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser.

  10. Crystal structure of 2-methoxy-1-nitronaphthalene

    Directory of Open Access Journals (Sweden)

    Hasna Yassine

    2015-10-01

    Full Text Available The asymmetric unit of the title compound, C11H9NO3, contains two molecules, A and B. In molecule A, the dihedral angle between the planes of the naphthalene ring system (r.m.s. deviation = 0.003 Å and the nitro group is 89.9 (2°, and the C atom of the methoxy group deviates from the naphthyl plane by 0.022 (2 Å. Equivalent data for molecule B are 0.008 Å, 65.9 (2° and −0.198 (2 Å, respectively. In the crystal, molecules are linked by weak C—H...O interactions, forming [100] chains of alternating A and B molecules. Weak aromatic π–π stacking contacts, with a range of centroid–centroid distances from 3.5863 (9 to 3.8048 (9 Å, are also observed.

  11. Synthesis and Crystal Structure of Isosteviol Derivatives

    Institute of Scientific and Technical Information of China (English)

    Tao Jing-Chao; Tian Guo-Qiang; Zhang Yan-Bing; Wu Ya; Liu Hong-Min

    2004-01-01

    Isosteviol (ent-16-ketobeyeran-19-oic acid, I) is a tetracyclic diterpenoid with a beyerane skeleton obtained by acid hydrolysis of stevioside.1 Several tetracyclic diterpenoids, specially the kaurenes, have important biological activities. Recent studies on the microbial transformation of isosteviol have revealed that it is metabolized by Cunninghamella bainieri, Actinoplanes sp., Mucor recurvatus, and Cunninghamella blackesleeana to yield five new metabolites.2 The hydroxylation pattern of these bioactive compounds may influence their binding on to the receptors, as was proposed for the Rabdosia diterpenoids. Therefore, the introduction of hydroxyl groups or unsaturated bonds in saturated and non-hydroxylated diterpenoids, like isosteviol, may enhance existing properties or lead to new biological activities. Although some beyeranes have been subjected to biotransformations by fungi,4 there are few report in the literature related the chemical transformation of Isosteviol. In the present study, we try to develop the chemical transformation of isosteviol and other beyeranes in order to obtaining some bioactive compounds with beyerane skeleton. Seven isosteviol derivatives, Ⅱ-Ⅷ, were therefore synthesized and characterized. The X-ray crystal strcture of H(R = H) was also determined.

  12. Photonics of liquid-crystal structures: A review

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P., E-mail: palto@online.ru; Blinov, L. M.; Barnik, M. I.; Lazarev, V. V.; Umanskii, B. A.; Shtykov, N. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2011-07-15

    The original results of studies of the electro-optical and laser effects which have been performed at the Laboratory of Liquid Crystals of the Institute of Crystallography, Russian Academy of Sciences, over the last few years are reviewed. Cholesteric liquid crystals as vivid representatives of photonic structures and their behavior in an electric field are considered in detail. The formation of higher harmonics in the periodic distribution of the director field in a helical liquid crystal structure and, correspondingly, the new (anharmonic) mode of electro-optical effects are discussed. Another group of studies is devoted to bistable light switching by an electric field in chiral nematics. Polarization diffraction gratings controlled by an electric field are also considered. The results of studies devoted to microlasers on various photonic structures with cholesteric and nematic liquid crystals are considered in detail. Particular attention is given to the new regime: leaky-mode lasing. Designs of liquid crystal light amplifiers and their polarization, field, and spectral characteristics are considered in the last section.

  13. The crystal structure and twinning of neodymium gallium perovskite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ubizskii, S.B.; Vasylechko, L.O.; Savytskii, D.I.; Matkovskii, A.O.; Syvorotka, I.M. [Res. Production Amalgamation Carat, L' viv (Ukraine)

    1994-10-01

    By means of X-ray structure analysis, the crystal structure of neodymium gallium perovskite (NGP) single crystals (NdGaO{sub 3}) being used as a substrate for HTSC film epitaxy has been refined and the position of atoms has been determined. The possibility of YBa{sub 2}Cu{sub 3}O{sub 7-x} film epitaxy on the plane (110) of NGP crystal as well as its advantages and pitfalls are analysed from structural data. The twinning types in the NGP crystal were established. The twinning structure of NGP substrates is found to be stable up to a temperature of 1173 K, as differentiated from the LaGaO{sub 3} and LaAlO{sub 3} substrates. It is intimated that the twinning in the NGP substrates oriented as (001) can result in creation of 90 degrees twin bonds in a film, and in the case of (110)-oriented plates it is possible to ignore the twinning presence in substrate completely. (author)

  14. CRYSTAL STRUCTURE ANALYSIS OF A PUTATIVE OXIDOREDUCTASE FROM KLEBSIELLA PNEUMONIAE

    Energy Technology Data Exchange (ETDEWEB)

    Baig, M.; Brown, A.; Eswaramoorthy, S.; Swaminathan, S.

    2009-01-01

    Klebsiella pneumoniae, a gram-negative enteric bacterium, is found in nosocomial infections which are acquired during hospital stays for about 10% of hospital patients in the United States. The crystal structure of a putative oxidoreductase from K. pneumoniae has been determined. The structural information of this K. pneumoniae protein was used to understand its function. Crystals of the putative oxidoreductase enzyme were obtained by the sitting drop vapor diffusion method using Polyethylene glycol (PEG) 3350, Bis-Tris buffer, pH 5.5 as precipitant. These crystals were used to collect X-ray data at beam line X12C of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). The crystal structure was determined using the SHELX program and refi ned with CNS 1.1. This protein, which is involved in the catalysis of an oxidation-reduction (redox) reaction, has an alpha/beta structure. It utilizes nicotinamide adenine dinucleotide phosphate (NADP) or nicotine adenine dinucleotide (NAD) to perform its function. This structure could be used to determine the active and co-factor binding sites of the protein, information that could help pharmaceutical companies in drug design and in determining the protein’s relationship to disease treatment such as that for pneumonia and other related pathologies.

  15. STRUCTURE FORMATION OF COLLOIDS IN NEMATIC LIQUID CRYSTALS

    Directory of Open Access Journals (Sweden)

    B.I.Lev

    2003-01-01

    Full Text Available We investigated the behaviour of colloidal particles suspended in nematic liquid crystals. These colloidal particles interact through elastic deformation of the nematic director field which can result in nontrivial collective behavior, leading to the formation of spatially modulated structures. In this paper, the formation of lattice structures is described both by computer simulations and by analytical theory. Effective interactions of the pairs of spherical macroparticles suspended in nematic liquid crystals have been suggested by many authors. Using these pairwise interactions, spatial structures are obtained by means of dynamic simulations. We have suggested a number of possible structures, which may be formed in multi-macroparticle systems. Regions of temperatures and concentrations are determined in which such a structure might appear.

  16. The crystal structure of samarosporin I at atomic resolution.

    Science.gov (United States)

    Gessmann, Renate; Axford, Danny; Evans, Gwyndaf; Brückner, Hans; Petratos, Kyriacos

    2012-11-01

    The atomic resolution structures of samarosporin I have been determined at 100 and 293 K. This is the first crystal structure of a natural 15-residue peptaibol. The amino acid sequence in samarosporin I is identical to emerimicin IV and stilbellin I. Samarosporin is a peptide antibiotic produced by the ascomycetous fungus Samarospora rostrup and belongs to peptaibol subfamily 2. The structures at both temperatures are very similar to each other adopting mainly a 3₁₀-helical and a minor fraction of α-helical conformation. The helices are significantly bent and packed in an antiparallel fashion in the centered monoclinic lattice leaving among them an approximately 10-Å channel extending along the crystallographic twofold axis. Only two ordered water molecules per peptide molecule were located in the channel. Comparisons have been carried out with crystal structures of subfamily 2 16-residue peptaibols antiamoebin and cephaibols. The repercussion of the structural analysis of samarosporin on membrane function is discussed.

  17. Temperature dependence of crystal structure and digestibility of roasted diaspore

    Institute of Scientific and Technical Information of China (English)

    周秋生; 李小斌; 彭志宏; 刘桂华

    2004-01-01

    Through X-ray diffraction patterns and scanning electronic micrographs, temperature dependence of the crystal structure of roasted diasporic bauxite at different temperatures and the digestibility of roasting production were investigated systematically. The lattice parameters of unit cell for chemically purified diaspore and unequilibrium alumina-contained oxide obtained from the diaspore roasted at different temperatures were determined. It is found that, with roasting temperature increasing, the roasting production changes from the original dense and perfect diaspore crystal into imperfect corundum with many microcracks and small pores on its surface and then into perfect corundum with low digestibility. The optimum roasting temperature with best digestibility is approximately 525 ℃ when residence time is about 25 min. It is thought that the change of crystal structure, formation of microcracks and small pores in the temperature field are the main essential reasons for improving digestibility of diasporic bauxite and its roasting production.

  18. Preparation, structural, and calorimetric characterization of bicomponent metallic photonic crystals

    Science.gov (United States)

    Kozlov, M. E.; Murthy, N. S.; Udod, I.; Khayrullin, I. I.; Baughman, R. H.; Zakhidov, A. A.

    2007-03-01

    We report preparation and characterization of novel bicomponent metal-based photonic crystals having submicron three-dimensional (3D) periodicity. Fabricated photonic crystals include SiO2 sphere lattices infiltrated interstitially with metals, carbon inverse lattices filled with metal or metal alloy spheres, Sb inverse lattices, and Sb inverse lattices filled with Bi spheres. Starting from a face centered SiO2 lattice template, these materials were obtained by sequences of either templating and template extraction or templating, template extraction, and retemplating. Surprising high fidelity was obtained for all templating and template extraction steps. Scanning electron microscopy (SEM), small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to characterize the structure and the effects of the structure on calorimetric properties. To the best of our knowledge, SAXS data on metallic photonic crystals were collected for first time.

  19. Preparation, structural, and calorimetric characterization of bicomponent metallic photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, M.E.; Baughman, R.H.; Zakhidov, A.A. [The University of Texas at Dallas, NanoTech Institute, Richardson, TX (United States); Murthy, N.S. [University of Vermont, Department of Physics, Burlington, VT (United States); Udod, I. [Teva Pharmaceuticals USA, Fairfield, NJ (United States); Khayrullin, I.I. [eMagin Corporation, Hopewell Junction, NY (United States)

    2007-03-15

    We report preparation and characterization of novel bicomponent metal-based photonic crystals having submicron three-dimensional (3D) periodicity. Fabricated photonic crystals include SiO{sub 2} sphere lattices infiltrated interstitially with metals, carbon inverse lattices filled with metal or metal alloy spheres, Sb inverse lattices, and Sb inverse lattices filled with Bi spheres. Starting from a face centered SiO{sub 2} lattice template, these materials were obtained by sequences of either templating and template extraction or templating, template extraction, and retemplating. Surprising high fidelity was obtained for all templating and template extraction steps. Scanning electron microscopy (SEM), small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) were used to characterize the structure and the effects of the structure on calorimetric properties. To the best of our knowledge, SAXS data on metallic photonic crystals were collected for first time. (orig.)

  20. Crystal Structure Representations for Machine Learning Models of Formation Energies

    CERN Document Server

    Faber, Felix; von Lilienfeld, O Anatole; Armiento, Rickard

    2015-01-01

    We introduce and evaluate a set of feature vector representations of crystal structures for machine learning (ML) models of formation energies of solids. ML models of atomization energies of organic molecules have been successful using a Coulomb matrix representation of the molecule. We consider three ways to generalize such representations to periodic systems: (i) a matrix where each element is related to the Ewald sum of the electrostatic interaction between two different atoms in the unit cell repeated over the lattice; (ii) an extended Coulomb-like matrix that takes into account a number of neighboring unit cells; and (iii) an Ansatz that mimics the periodicity and the basic features of the elements in the Ewald sum matrix by using a sine function of the crystal coordinates of the atoms. The representations are compared for a Laplacian kernel with Manhattan norm, trained to reproduce formation energies using a data set of 3938 crystal structures obtained from the Materials Project. For training sets consi...

  1. Synthesis and crystal structures of three new benzotriazolylpropanamides

    Directory of Open Access Journals (Sweden)

    Donna S. Amenta

    2017-06-01

    Full Text Available The base-catalyzed Michael addition of 2-methylacrylamide to benzotriazole afforded 3-(1H-benzotriazol-1-yl-2-methylpropanamide, C10H12N4O (1, in 32% yield in addition to small amounts of isomeric 3-(2H-benzotriazol-2-yl-2-methylpropanamide, C10H12N4O (2. In a similar manner, 3-(1H-benzotriazol-1-yl-N,N-dimethylpropanamide, C11H14N4O (3, was prepared from benzotriazole and N,N-dimethylacrylamide. All three products have been structurally characterized by single-crystal X-ray diffraction. The crystal structures of 1 and 2 comprise infinite arrays formed by N—H...O and N—H...N bridges, as well as π–π interactions, while the molecules of 3 are aggregated to simple π-dimers in the crystal.

  2. Diamond-Structured Photonic Crystals with Graded Air Spheres Radii

    Directory of Open Access Journals (Sweden)

    Dichen Li

    2012-05-01

    Full Text Available A diamond-structured photonic crystal (PC with graded air spheres radii was fabricated successfully by stereolithography (SL and gel-casting process. The graded radii in photonic crystal were formed by uniting different radii in photonic crystals with a uniform radius together along the Г‑Х direction. The stop band was observed between 26.1 GHz and 34.3 GHz by reflection and transmission measurements in the direction. The result agreed well with the simulation attained by the Finite Integration Technique (FIT. The stop band width was 8.2 GHz and the resulting gap/midgap ratio was 27.2%, which became respectively 141.4% and 161.9% of the perfect PC. The results indicate that the stop band width of the diamond-structured PC can be expanded by graded air spheres radii along the Г‑Х direction, which is beneficial to develop a multi bandpass filter.

  3. Single crystal surface structure by bragg scattering

    DEFF Research Database (Denmark)

    Nielsen, Mogens

    1985-01-01

    X-ray diffraction is becoming an important tool in the measurements of surface structures. Single crystalline samples are used as in Low Energy Electron Diffraction (LEED)-studies. The X-ray technique is somewhat more involved due to the need of bright, collimated photon sources, in general...... synchrotron X-rays, and of very accurate angular settings in the ultrahigh-vacuum environment of the sample. We present the technique and discuss examples of experimental results....

  4. Fine structure of fields in 2D photonic crystal waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Volkov, V. S.; Bozhevolnyi, S. I.

    2006-01-01

    We resolve fine structure of fields in a single-row missing photonic crystal waveguide by finite-difference time-domain modelling and SNOM measurements. Both linear dispersion and slow-light regimes in proximity of the cutoff are addressed in the analysis....

  5. Crystal and molecular structure of lancerodiol-p-hydroxybenzoate

    Directory of Open Access Journals (Sweden)

    Mohamed H Abd El-Razek

    2010-01-01

    Full Text Available Lancerodiol-p-hydroxybenzoate was isolated from the leaves of Ferula sinaica L. (Apiaceae as light needle crystals. This work reports for the first time the molecular structure and relative configuration of compound 1, established by X-ray analysis.

  6. Ultrafast investigations of slow light in photonic crystal structures

    NARCIS (Netherlands)

    Engelen, Rob Jacques Paul

    2008-01-01

    Optical structures with dimensions down to nanometer length scales have been a topic for investigation for an increasing number of researchers, due to their intriguing physical properties and their possible new optical applications. In this thesis, waveguides in two-dimensional photonic crystals are

  7. Topology optimization for transient response of photonic crystal structures

    DEFF Research Database (Denmark)

    Matzen, René; Jensen, Jakob Søndergaard; Sigmund, Ole

    2010-01-01

    An optimization scheme based on topology optimization for transient response of photonic crystal structures is developed. The system response is obtained by a finite-element time-domain analysis employing perfectly matched layers as an absorbing boundary condition. As an example a waveguide...

  8. Redetermination of the Crystal Structure of Al2Br6

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Poulsen, Finn W.; Nielsen, Kurt

    1997-01-01

    The structure of aluminium bromide has been reinvestigated by X-ray diffraction in three different ways: (a) on a single crystal grown in a glass capillary, (b) on powder in a Debye-Scherrer glass capillary and (c) on an area of powder placed in a protective container for Bragg-Brentano geometry....

  9. Crystal structure of sucrose phosphorylase from Bifidobacterium adolescentis.

    NARCIS (Netherlands)

    Sprogoe, D.; Broek, van den L.A.M.; Mirza, O.; Kastrup, J.S.; Voragen, A.G.J.; Gajhede, M.; Skov, L.K.

    2004-01-01

    Around 80 enzymes are implicated in the generic starch and sucrose pathways. One of these enzymes is sucrose phosphorylase, which reversibly catalyzes the conversion of sucrose and orthophosphate to d-Fructose and a-d-glucose 1-phosphate. Here, we present the crystal structure of sucrose phosphoryla

  10. Crystal structure of the sodium-potassium pump

    DEFF Research Database (Denmark)

    Morth, J Preben; Pedersen, Bjørn Panyella; Toustrup-Jensen, Mads S;

    2007-01-01

    The Na+,K+-ATPase generates electrochemical gradients for sodium and potassium that are vital to animal cells, exchanging three sodium ions for two potassium ions across the plasma membrane during each cycle of ATP hydrolysis. Here we present the X-ray crystal structure at 3.5 A resolution of the...

  11. Optically induced structural phase transitions in ion Coulomb crystals

    DEFF Research Database (Denmark)

    Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael

    2012-01-01

    , such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit...

  12. Materials research at Stanford University. [composite materials, crystal structure, acoustics

    Science.gov (United States)

    1975-01-01

    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  13. Unusual Features of Crystal Structures of Some Simple Copper Compounds

    Science.gov (United States)

    Douglas, Bodie

    2009-01-01

    Some simple copper compounds have unusual crystal structures. Cu[subscript 3]N is cubic with N atoms at centers of octahedra formed by 6 Cu atoms. Cu[subscript 2]O (cuprite) is also cubic; O atoms are in tetrahedra formed by 4 Cu atoms. These tetrahedra are linked by sharing vertices forming two independent networks without linkages between them.…

  14. A unified picture of the crystal structures of metals

    Science.gov (United States)

    Söderlind, Per; Eriksson, Olle; Johansson, Börje; Wills, J. M.; Boring, A. M.

    1995-04-01

    THE crystal structures of the light actinides have intrigued physicists and chemists for several decades1. Simple metals and transition metals have close-packed, high-symmetry structures, such as body-centred cubic, face-centred cubic and hexagonal close packing. In contrast, the structures of the light actinides are very loosely packed and of low symmetry-tetragonal, orthorhombic and monoclinic. To understand these differences, we have performed total-energy calculations, as a function of volume, for both high-and low-symmetry structures of a simple metal (aluminium), a non-magnetic transition metal (niobium), a ferromagnetic transition metal (iron) and a light actinide (uranium). We find that the crystal structure of all of these metals is determined by the balance between electrostatic (Madelung) interactions, which favour high symmetry, and a Peierls distortion of the crystal lattice, which favours low symmetry. We show that simple metals and transition metals can adopt low-symmetry structures on expansion of the lattice; and we predict that, conversely, the light actinides will undergo transitions to structures of higher symmetry on compression.

  15. VO{sub 2} (A): Reinvestigation of crystal structure, phase transition and crystal growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Rao Popuri, Srinivasa [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Plautius Andronescu Str. No. 1, 300224 Timisoara (Romania); Artemenko, Alla [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); Labrugere, Christine [CeCaMA, University of Bordeaux 1, ICMCB, 87 Avenue du Dr. A. Schweitzer, F-33608 Pessac (France); Miclau, Marinela [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Plautius Andronescu Str. No. 1, 300224 Timisoara (Romania); Villesuzanne, Antoine [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); Pollet, Michaël, E-mail: pollet@icmcb-bordeaux.cnrs.fr [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France)

    2014-05-01

    Well crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal reaction in the presence of V{sub 2}O{sub 5} and oxalic acid. With the advantage of high crystalline samples, we propose P4/ncc as an appropriate space group at room temperature. From morphological studies, we found that the oriented attachment and layer by layer growth mechanisms are responsible for the formation of VO{sub 2} (A) micro rods. The structural and electronic transitions in VO{sub 2} (A) are strongly first order in nature, and a marked difference between the structural transition temperatures and electronic transitions temperature was evidenced. The reversible intra- (LTP-A to HTP-A) and irreversible inter- (HTP-A to VO{sub 2} (M1)) structural phase transformations were studied by in-situ powder X-ray diffraction. Attempts to increase the size of the VO{sub 2} (A) microrods are presented and the possible formation steps for the flower-like morphologies of VO{sub 2} (M1) are described. - Graphical abstract: Using a single step and template free hydrothermal synthesis, well crystallized VO{sub 2} (A) microrods were prepared and the P4/ncc space group was assigned to the room temperature crystal structure. Reversible and irreversible phase transitions among different VO{sub 2} polymorphs were identified and their progressive nature was highlighted. Attempts to increase the microrods size, involving layer by layer formation mechanisms, are presented. - Highlights: • Highly crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal process. • The P4/ncc space group was determined for VO{sub 2} (A) at room temperature. • The electronic structure and progressive nature of the structural phase transition were investigated. • A weak coupling between structural and electronic phase transitions was identified. • Different crystallite morphologies were discussed in relation with growth mechanisms.

  16. Crystal structure and magnetization of a Co3B2O6 single crystal

    Science.gov (United States)

    Kazak, N. V.; Platunov, M. S.; Ivanova, N. B.; Knyazev, Yu. V.; Bezmaternykh, L. N.; Eremin, E. V.; Vasil'ev, A. D.; Bayukov, O. A.; Ovchinnikov, S. G.; Velikanov, D. A.; Zubavichus, Ya. V.

    2013-07-01

    The crystal structure and magnetic properties of Co3B2O6 single crystals are studied. Orthorhombic symmetry with space group Pnnm is detected at room temperature. The measurements of static magnetization and dynamic magnetic susceptibility reveal two magnetic anomalies at T 1 = 33 K and T 2 = 10 K and an easy-axis magnetic anisotropy. The effective magnetic moment indicates a high-spin state of the Co2+ ion. A spin-flop transition is found at low temperatures and H sf = 23 kOe. EXAFS spectra of the K-edge absorption of Co are recorded at various temperatures, the temperature-induced changes in the parameters of the local environment of cobalt are analyzed, and the effective Co-Co and Co-O distances are determined. The magnetic interactions in the crystal are analyzed in terms of an indirect coupling model.

  17. Band structures in Sierpinski triangle fractal porous phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai; Liu, Ying, E-mail: yliu5@bjtu.edu.cn; Liang, Tianshu

    2016-10-01

    In this paper, the band structures in Sierpinski triangle fractal porous phononic crystals (FPPCs) are studied with the aim to clarify the effect of fractal hierarchy on the band structures. Firstly, one kind of FPPCs based on Sierpinski triangle routine is proposed. Then the influence of the porosity on the elastic wave dispersion in Sierpinski triangle FPPCs is investigated. The sensitivity of the band structures to the fractal hierarchy is discussed in detail. The results show that the increase of the hierarchy increases the sensitivity of ABG (Absolute band gap) central frequency to the porosity. But further increase of the fractal hierarchy weakens this sensitivity. On the same hierarchy, wider ABGs could be opened in Sierpinski equilateral triangle FPPC; whilst, a lower ABG could be opened at lower porosity in Sierpinski right-angled isosceles FPPCs. These results will provide a meaningful guidance in tuning band structures in porous phononic crystals by fractal design.

  18. Crystal structure and stereochemistry study of 2-substituted benzoxazole derivatives.

    Science.gov (United States)

    Mabied, Ahmed F; Shalaby, Elsayed M; Zayed, Hamdia A; El-Kholy, Esmat; Farag, Ibrahim S A; Ahmed, Naima A

    2014-01-01

    The structure of 2-[(4-chlorophenylazo) cyanomethyl] benzoxazole, C15H9ClN4O (I), has triclinic ([Formula: see text]) symmetry. The structure displays N-H ⋯ N hydrogen bonding. The structure of 2-[(arylidene) cyanomethyl] benzoxazoles, C17H10N2O3 (II), has triclinic ([Formula: see text]) symmetry. The structure displays C-H ⋯ N, C-H ⋯ C hydrogen bonding. In (I), the chlorophenyl and benzoxazole groups adopt a trans configuration with respect to the central cyanomethyle hydrazone moiety. Compound (II) crystallized with two molecules in the asymmetric unit shows cisoid conformation between cyano group and benzoxazole nitrogen, contrary to (I). In (II) the benzodioxole has an envelope conformation (the C17 atom is the flap atom). The molecular geometry obtained using molecular mechanics (MM) calculations has been discussed along with the results of single crystal analysis.

  19. Domain Structures in Nematic Liquid Crystals on a Polycarbonate Surface

    Directory of Open Access Journals (Sweden)

    Vasily F. Shabanov

    2013-08-01

    Full Text Available Alignment of nematic liquid crystals on polycarbonate films obtained with the use of solvents with different solvations is studied. Domain structures occurring during the growth on the polymer surface against the background of the initial thread-like or schlieren texture are demonstrated. It is established by optical methods that the domains are stable formations visualizing the polymer surface structures. In nematic droplets, the temperature-induced transition from the domain structure with two extinction bands to the structure with four bands is observed. This transition is shown to be caused by reorientation of the nematic director in the liquid crystal volume from the planar alignment to the homeotropic state with the pronounced radial configuration of nematic molecules on the surface. The observed textures are compared with different combinations of the volume LC orientations and the radial distribution of the director field and the disclination lines at the polycarbonate surface.

  20. Microprobe of structure of crystal/liquid interface boundary layers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The molecular structures and its evolutive regularities within the boundary layers in the crystal growth of KDP and DKDP have been studied in real time by using holography and Raman microprobe. The experiments show that the molecular structure of mother solution within the boundary layers is distinctly different from that of the solutions alone. In this paper, the effects of cations within the boundary layers on the structure of solution are considered. Within the characteristic boundary layers, the effects of cations cause the changes in O-P-O bond angle, electronic density redistribution of the phosphate groups, and significant changes in the bond intensity, thus leading to the breaking of partial hydrogen bonds of the phosphate associations, the readjustment of geometry of anionic phosphate groups and desolvation, and the forming of the smectic ordering structure of the anions_cations. Finally, the crystallization unit of anion_cation should be formed at the proximate interface.

  1. Crystal structures at high pressures and temperatures

    Science.gov (United States)

    Caldwell, Wendel Alexander

    2000-10-01

    The diamond anvil cell (DAC) is a unique instrument that can generate pressures equivalent to those inside planetary interiors (pressures on the order of 1 million atmospheres) under sustained conditions. When combined with a bright source of collimated x-rays, the DAC can be used to probe the structure of materials in-situ at ultra-high pressures. An understanding of the high-pressure structure of materials is important in determining what types of processes may take place in the Earth at great depths. Motivated by previous studies showing that xenon becomes metallic at pressures above ˜1 megabar (100 GPa), we examined the stable structures and reactivity of xenon at pressures approaching that of the core-mantle boundary in the Earth. Our findings indicate the transformation of xenon from face-centered cubic (fcc) to hexagonal close-packed (hcp) structures is kinetically hindered at room temperature, with the equilibrium fcc--hcp phase boundary at 21 (+/-3) gigapascals, a pressure lower than was previously thought. Additionally, we find no tendency on the part of xenon to form a metal alloy with iron or platinum to at least 100 to 150 gigapascals, making it unlikely that the Earth's core serves as a reservoir for primordial xenon. Measurements of the compressibility of natural (Mg.75,Fe .25)2SiO4 gamma-spinel at pressures of the Earth's transition zone yield a pressure derivative of the bulk modulus K0 ' = 6.3 (+/-0.3). As gamma-spinel is considered to be a dominant mineral phase of the transition-zone of the Earth's mantle (400--670 km depth), the relatively high value of K0' for gamma-spinel may help explain the rapid increase with depth of seismic velocities through the transition zone. The thermodynamics, mechanisms and kinetics of pressure-induced amorphization are not well understood. We report here new studies indicating little or no entropy difference between the crystalline and glassy states of Ca(OH) 2 (portlandite). Additional work on the pressure

  2. Crystal Structure of Cold Compressed Graphite

    Science.gov (United States)

    Amsler, Maximilian; Flores-Livas, José A.; Lehtovaara, Lauri; Balima, Felix; Ghasemi, S. Alireza; Machon, Denis; Pailhès, Stéphane; Willand, Alexander; Caliste, Damien; Botti, Silvana; San Miguel, Alfonso; Goedecker, Stefan; Marques, Miguel A. L.

    2012-02-01

    Through a systematic structural search we found an allotrope of carbon with Cmmm symmetry which we predict to be more stable than graphite for pressures above 10 GPa. This material, which we refer to as Z-carbon, is formed by pure sp3 bonds and it provides an explanation to several features in experimental x-ray diffraction and Raman spectra of graphite under pressure. The transition from graphite to Z-carbon can occur through simple sliding and buckling of graphene sheets. Our calculations predict that Z-carbon is a transparent wide band-gap semiconductor with a hardness comparable to diamond.

  3. Single Crystal Structure Determination of Alumina to 1 Mbar

    Science.gov (United States)

    Dong, H.; Zhang, L.; Prakapenka, V.; Mao, H.

    2014-12-01

    Aluminum oxide (Al2O3) is an important ceramic material and a major oxide in the earth. Additionally, alumina is a widely used pressure standard in static high-pressure experiments (Cr3+-bearing corundum, ruby). The changes of its crystal structure with pressure (P) and temperature (T) are important for its applications and understanding its physical properties in the deep Earth. There have been numerous reports on the high P-T polymorphs of alumina. Previous theoretical calculations and experiments suggest that the crystal structure of Al2O3 evolves greatly at high P-T. In this study, we used the newly developed multigrain crystallography method combined with single-crystal x-ray diffraction analysis technique for the structure determination of alumina at high P-T to provide single-crystal structure refinement for high-pressure phases of Al2O3. Alumina powder was mixed with ~10% Pt and Ne was used as both pressure transmitting media and thermal insulating layers during laser-heating. Coarse-grained aggregates of Al2O3 were synthesized in a laser-heated diamond anvil cell. The structure change of Al2O3 was monitored by in situ x-ray diffraction at ~1 Mbar and 2700 K. The results allow us to distinguish the structural differences between the Rh2O3 (II) structure (space group Pbcn) and perovskite structure (space group Pbnm) for the first high-pressure phase of Al2O3. More detailed results will be discussed in the later work.

  4. Thermodynamics of sublimation, crystal lattice energies, and crystal structures of racemates and enantiomers: (+)- and (+/-)-ibuprofen.

    Science.gov (United States)

    Perlovich, German L; Kurkov, Sergey V; Hansen, Lars Kr; Bauer-Brandl, Annette

    2004-03-01

    Thermodynamic differences between ibuprofen (IBP) racemate and the (+)-enantiomer were studied by X-ray diffraction, thermoanalysis, and crystal energy calculations. The thermodynamic functions of sublimation (as a measure of crystal lattice energy) were obtained by the transpiration method. The sublimation enthalpies (DeltaH(sub)) of (+/-)-IBP and (+)-IBP are 115.8 +/- 0.6 and 107.4 +/- 0.5 kJ. mol(-1), respectively. Using the temperature dependency of the saturated vapor pressure, the relative fractions of enthalpy and entropy of the sublimation process were calculated, and the sublimation process for both the racemate and the enantiomer was found to be enthalpy driven (62%). Two different force fields, Mayo et al. (M) and Gavezzotti (G), were used for comparative analysis of crystal lattice energies. Both force fields revealed that the van der Waals term contributes more to the packing energy in (+)-IBP than in (+/-)-IBP. The hydrogen bonding energy, however, contributes at 29.7 and 32.3% to the total crystal lattice energy in (+)-IBP and (+/-)-IBP (M), respectively. Furthermore, different structure fragments of the IBP molecule were analyzed with respect to their contribution to nonbonded van der Waals interactions. The effect of the C-H distance on the van der Waals term of the crystal lattice energy was also studied.

  5. Coefficient of crystal lattice matching as a parameter of substrate - crystal structure compatibility in silumins

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2009-07-01

    Full Text Available Adding high-melting point elements (Mo, Nb, Ni, Ti, W to complex silumins results in hardening of the latter ones, owing to the formation of new intermetallic phases of the AlxMey type, with refinement of dendrites in α solution and crystals in β phase. The hardening is also due to the effect of various inoculants. An addition of the inoculant is expected to form substrates, the crystal lattice of which, or some (privileged lattice planes and interatomic spaces should bear a strong resemblance to the crystal nucleus. To verify this statement, using binary phase equilibria systems, the coefficient of crystal lattice matching, being one of the measures of the crystallographic similarity, was calculated. A compatibility of this parameter (up to 20% may decide about the structure compatibility between the substrate and crystal which, in turn, is responsible for the effectiveness of alloy modification. Investigations have proved that, given the temperature range of their formation, the density, the lattice type, and the lattice parameter, some intermetallic phases of the AlxMey type can act as substrates for the crystallisation of aluminium and silicon, and some of the silumin hardening phases.

  6. Structural evolution in the crystallization of rapid cooling silver melt

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Z.A., E-mail: ze.tian@gmail.com [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Dong, K.J.; Yu, A.B. [Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2015-03-15

    The structural evolution in a rapid cooling process of silver melt has been investigated at different scales by adopting several analysis methods. The results testify Ostwald’s rule of stages and Frank conjecture upon icosahedron with many specific details. In particular, the cluster-scale analysis by a recent developed method called LSCA (the Largest Standard Cluster Analysis) clarified the complex structural evolution occurred in crystallization: different kinds of local clusters (such as ico-like (ico is the abbreviation of icosahedron), ico-bcc like (bcc, body-centred cubic), bcc, bcc-like structures) in turn have their maximal numbers as temperature decreases. And in a rather wide temperature range the icosahedral short-range order (ISRO) demonstrates a saturated stage (where the amount of ico-like structures keeps stable) that breeds metastable bcc clusters. As the precursor of crystallization, after reaching the maximal number bcc clusters finally decrease, resulting in the final solid being a mixture mainly composed of fcc/hcp (face-centred cubic and hexagonal-closed packed) clusters and to a less degree, bcc clusters. This detailed geometric picture for crystallization of liquid metal is believed to be useful to improve the fundamental understanding of liquid–solid phase transition. - Highlights: • A comprehensive structural analysis is conducted focusing on crystallization. • The involved atoms in our analysis are more than 90% for all samples concerned. • A series of distinct intermediate states are found in crystallization of silver melt. • A novelty icosahedron-saturated state breeds the metastable bcc state.

  7. Tailor-made force fields for crystal-structure prediction.

    Science.gov (United States)

    Neumann, Marcus A

    2008-08-14

    A general procedure is presented to derive a complete set of force-field parameters for flexible molecules in the crystalline state on a case-by-case basis. The force-field parameters are fitted to the electrostatic potential as well as to accurate energies and forces generated by means of a hybrid method that combines solid-state density functional theory (DFT) calculations with an empirical van der Waals correction. All DFT calculations are carried out with the VASP program. The mathematical structure of the force field, the generation of reference data, the choice of the figure of merit, the optimization algorithm, and the parameter-refinement strategy are discussed in detail. The approach is applied to cyclohexane-1,4-dione, a small flexible ring. The tailor-made force field obtained for cyclohexane-1,4-dione is used to search for low-energy crystal packings in all 230 space groups with one molecule per asymmetric unit, and the most stable crystal structures are reoptimized in a second step with the hybrid method. The experimental crystal structure is found as the most stable predicted crystal structure both with the tailor-made force field and the hybrid method. The same methodology has also been applied successfully to the four compounds of the fourth CCDC blind test on crystal-structure prediction. For the five aforementioned compounds, the root-mean-square deviations between lattice energies calculated with the tailor-made force fields and the hybrid method range from 0.024 to 0.053 kcal/mol per atom around an average value of 0.034 kcal/mol per atom.

  8. Crystal structure of alpha poly-p-xylylene.

    Science.gov (United States)

    Kubo, S.; Wunderlich, B.

    1971-01-01

    A crystal structure of alpha poly-p-xylylene is proposed with the help of data of oriented crystals grown during polymerization. The unit cell is monoclinic with the parameters a = 8.57 A, b = 10.62 A, c = 6.54 A (chain axis), and beta = 101.3 deg. Four repeating units per cell lead to a calculated density of 1.185 g/cu cm and a packing density of 0.71. The probable space group is P2 sub 1/m.

  9. Modulation mechanism and disorder structure in hollandite-type crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wu Xiaojing; Fujiki, Yoshiki; Horiuchi, Shigeo (National Inst. for Research in Inorganic Materials, Ibaraki (Japan)); Ishigame, Mareo (Research Inst. for Scientific Measurements, Tohoku Univ., Sendai (Japan))

    1991-07-01

    The structural modulation in some hollandite-type crystals is explained by a vacancy-displacive modulation model. In this model the large cations located in the tetragonal channels along the c axis deviate from the average position to form a modulation wave. Three types of disorder in the initial phase of the modulation wave have been introduced to interpret apparently different diffraction patterns in hollandite-type crystals. A mathematical analysis as well as optical diffraction give results similar to those experimentally observed. High-resolution transmission electron microscope images have been observed to confirm the discussion further. (orig.).

  10. Crystal structure of bis-(9H-6-amino-purin-1-ium) hexa-fluorido-silicate(IV) dihydrate.

    Science.gov (United States)

    Belhouas, Ratiba; Bouacida, Sofiane; Boudaren, Chaouki; Daran, Jean-Claude; Chtoun, El Hossain

    2015-02-01

    The asymmetric unit of the title compound, 2C5H6N5 (+)·SiF6 (2-)·2H2O, contains one adeninium cation, half of a hexa-fluorido-silicate anion located on an inversion centre and one lattice water mol-ecule. The adeninium cations are connected through N-H⋯N hydrogen bonds involving one H atom of the -NH2 group and the H atom of the protonated N atom of the adenine ring system, forming centrosymmetric ring motifs of the type R 2 (2)(10) and R 2 (2)(8), respectively. The overall connection of the cation leads to the formation of planar ribbons parallel to (122). In the ribbons, slipped π-π stacking inter-actions, with a centroid-to-centroid distance of 3.6938 (9) Å, an inter-planar distance of 3.455 Å and a slippage of 1.306 Å is observed. The hexa-fluorido-silicate anion and the water mol-ecule are linked through O-H⋯F hydrogen bonds [ring motif R 4 (4)(12)] into chains parallel to [100]. The cationic ribbons and anionic chains are finally connected through additional N-H⋯O, N-H⋯F and O-H⋯F hydrogen bonds into a three-dimensional network in which layers of adeninium cations and fluorido-silicate anions alternate parallel to (001).

  11. Crystal structure of bis-(di-methyl-ammonium) hexa-aqua-nickel(II) bis-(sulfate) dihydrate.

    Science.gov (United States)

    Held, Peter

    2014-11-01

    In the title salt, (C2H8N)2[Ni(H2O)6)](SO4)2·2H2O, the Ni(II) cation is located on a centre of inversion and exhibits a slightly distorted octa-hedral arrangement of water mol-ecules. The Ni-O bond lengths in the complex [Ni(H2O)6](2+) cation show a distribution as in the related Tutton salt (NH4)2[Ni(H2O)6](SO4)2, but are longer in average [2.056 (13) versus 2.037 (12) Å]. The noncoordinating water mol-ecules and di-methyl-ammonium cations connect the sulfate and [Ni(H2O)6](2+) octa-hedra via O-H⋯O and N-H⋯O hydrogen bonds from weak up to medium strength into a three-dimensional framework whereby the complex metal cations and sulfate anions are arranged in sheets parallel (001).

  12. Crystal Structure of Triosephosphate Isomerase from Trypanosoma cruzi in Hexane

    Science.gov (United States)

    Gao, Xiu-Gong; Maldonado, Ernesto; Perez-Montfort, Ruy; Garza-Ramos, Georgina; Tuena de Gomez-Puyou, Marietta; Gomez-Puyou, Armando; Rodriguez-Romero, Adela

    1999-08-01

    To gain insight into the mechanisms of enzyme catalysis in organic solvents, the x-ray structure of some monomeric enzymes in organic solvents was determined. However, it remained to be explored whether the structure of oligomeric proteins is also amenable to such analysis. The field acquired new perspectives when it was proposed that the x-ray structure of enzymes in nonaqueous media could reveal binding sites for organic solvents that in principle could represent the starting point for drug design. Here, a crystal of the dimeric enzyme triosephosphate isomerase from the pathogenic parasite Trypanosoma cruzi was soaked and diffracted in hexane and its structure solved at 2- angstrom resolution. Its overall structure and the dimer interface were not altered by hexane. However, there were differences in the orientation of the side chains of several amino acids, including that of the catalytic Glu-168 in one of the monomers. No hexane molecules were detected in the active site or in the dimer interface. However, three hexane molecules were identified on the surface of the protein at sites, which in the native crystal did not have water molecules. The number of water molecules in the hexane structure was higher than in the native crystal. Two hexanes localized at <4 angstrom from residues that form the dimer interface; they were in close proximity to a site that has been considered a potential target for drug design.

  13. Modeling liquid crystal bilayer structures with minimal surfaces.

    Science.gov (United States)

    Enlow, J D; Enlow, R L; McGrath, K M; Tate, M W

    2004-01-22

    This paper describes a new convenient and accurate method of calculating x-ray diffraction integrated intensities from detailed cubic bilayer structures. The method is employed to investigate the structure of a particular surfactant system (didodecyldimethylammonium bromide in a solution of oil and heavy water), for which single-crystal experimental data have recently been collected. The diffracted peak intensities correlate well with theoretical structures based on mathematical minimal surfaces. Optimized electron density profiles of the bilayer are presented, providing new insight into key features of the bilayer structure.

  14. Crystal structure of (1S,3R,8R,9R,10S)-2,4,6-tris-(2,2-di-chloro-3,7,7,10-tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodec-9-yl)cyclo-triboroxane.

    Science.gov (United States)

    Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Mazoir, Noureddine; Berraho, Moha

    2015-08-01

    The title compound, C48H75B3Cl6O3, was synthesized in two steps from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-hept-ene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule consists of an almost planar cyclo-triboroxane ring [maximum deviation = 0.036 (2) Å] linked to three identical fused ring systems with different conformations. Each of the three attached ring systems is built up from a seven-membered ring to which a six- and a three-membered ring are fused. The three six-membered rings have a twist-boat conformation, whereas the seven-membered rings display boat, chair and twist-boat conformations. The dihedral angles between the central boroxane ring and the mean planes of the attached six-membered rings are 63.67 (18), 54.89 (2) and 56.57 (19)°. The crystal packing is governed only by van der Waals inter-actions.

  15. Crystal structure of N-(quinolin-6-ylhydroxylamine

    Directory of Open Access Journals (Sweden)

    Anuruddha Rajapakse

    2014-11-01

    Full Text Available The title compound, C9H8N2O, crystallized with four independent molecules in the asymmetric unit. The four molecules are linked via one O—H...N and two N—H...N hydrogen bonds, forming a tetramer-like unit. In the crystal, molecules are further linked by O—H...N and N—H...O hydrogen bonds forming layers parallel to (001. These layers are linked via C—H...O hydrogen bonds and a number of weak C—H...π interactions, forming a three-dimensional structure. The crystal was refined as a non-merohedral twin with a minor twin component of 0.319.

  16. Crystal structure and density of helium to 232 kbar

    Science.gov (United States)

    Mao, H. K.; Wu, Y.; Jephcoat, A. P.; Hemley, R. J.; Bell, P. M.; Bassett, W. A.

    1988-01-01

    The properties of helium and hydrogen at high pressure are topics of great interest to the understanding of planetary interiors. These materials constitute 95 percent of the entire solar system. A technique was presented for the measurement of X-ray diffraction from single-crystals of low-Z condenses gases in a diamond-anvil cell at high pressure. The first such single-crystal X-ray diffraction measurements on solid hydrogen to 26.5 GPa were presented. The application of this technique to the problem of the crystal structure, equation of state, and phase diagram of solid helium is reported. Crucial for X-ray diffraction studies of these materials is the use of a synchrotron radiation source which provides high brillance, narrow collimation of the incident and diffracted X-ray beams to reduce the background noise, and energy-dispersive diffraction techniques with polychromatic (white) radiation, which provides high detection efficiency.

  17. Crystal structure of bis(1-ethylpyridinium dioxonium hexacyanidoferrate(II

    Directory of Open Access Journals (Sweden)

    Rikako Tanaka

    2017-02-01

    Full Text Available The title compound, (C7H10N2(H3O2[Fe(CN6] or (Etpy2(H3O2[Fe(CN6] (Etpy+ is 1-ethylpyridinium, crystallizes in the space group Pnnm. The FeII atom of the [Fe(CN6]4− anion lies on a site with site symmetry ..2/m, and has an octahedral coordination sphere defined by six cyanido ligands. Both the Etpy+ and the oxonium cations are located on a mirror plane. In the crystal, electron-donor anions of [Fe(CN6]4− and electron-acceptor cations of Etpy+ are each stacked parallel to the b axis, resulting in a columnar structure with segregated moieties. The crystal packing is stabilized by a three-dimensional O—H...N hydrogen-bonding network between the oxonium ions and the cyanide ligands of [Fe(CN6]4−.

  18. Crystal Growth, Structure and Morphology of Rifapentine Methanol Solvate

    Institute of Scientific and Technical Information of China (English)

    周堃; 李军; 罗建洪; 金央

    2012-01-01

    Rifapentine, an important antibiotic, was crystallized from methanol solvent in the form of its methanol solvate. The crystal structure of rifapentine methanol solvate belongs to monoclinic, space group P21, with the unit cell parameters of a = 1.2278(3) nm, b = 1.9768(4) rim, c = 1.2473(3) nm, Z= 2, and β = 112.35(3). The parallelepiped.morphology was also predicted by Materials Studio simulation program.. The influence of intermolecular in-teraction was taken into account in the attachment energy model. The crystal shape fits the calculated morphology well, which was performed on the potential energy minimized model using a generic DREIDING 2.21 force fieldand developed minimization protocol with derived'partial charges.

  19. Synthesis and Crystal Structure of Tetranuclear Zinc Benzoate

    Institute of Scientific and Technical Information of China (English)

    YIN Ming-cai; WANG Chi-wei; AI Chang-chun; YUAN Liang-jie; SUN Ju-tang

    2004-01-01

    A tetranuclear zinc benzoate Zn4O(C6H5CO2)6 was synthesized and characterized by X-ray single crystal determination. It crystallizes in cubic, space group Ia-3d. Its crystal cell is very large, a=4.100 63(18) nm, V=68.953(5) nm3 and Z = 48. The structure is composed of discrete Zn4O(C6H5CO2)6 molecules. In each molecule, four zinc atoms are held together by a central oxygen atom, which results in the formation of a regular tetrahedron. All benzoate ligands coordinate to zinc atoms in a bidentate bridging mode. Each zinc atom is in a slightly distorted tetrahedral geometry, coordinated by three benzoate oxygen atoms and the central oxygen atom. The intermolecular interactions result in the formation of a three-dimensional supramolecular framework, with non-intersecting parallel channels.

  20. GPCR crystal structures: Medicinal chemistry in the pocket.

    Science.gov (United States)

    Shonberg, Jeremy; Kling, Ralf C; Gmeiner, Peter; Löber, Stefan

    2015-07-15

    Recent breakthroughs in GPCR structural biology have significantly increased our understanding of drug action at these therapeutically relevant receptors, and this will undoubtedly lead to the design of better therapeutics. In recent years, crystal structures of GPCRs from classes A, B, C and F have been solved, unveiling a precise snapshot of ligand-receptor interactions. Furthermore, some receptors have been crystallized in different functional states in complex with antagonists, partial agonists, full agonists, biased agonists and allosteric modulators, providing further insight into the mechanisms of ligand-induced GPCR activation. It is now obvious that there is enormous diversity in the size, shape and position of the ligand binding pockets in GPCRs. In this review, we summarise the current state of solved GPCR structures, with a particular focus on ligand-receptor interactions in the binding pocket, and how this can contribute to the design of GPCR ligands with better affinity, subtype selectivity or efficacy.

  1. Crystal structure of cytotoxin protein suilysin from Streptococcus suis.

    Science.gov (United States)

    Xu, Lingfeng; Huang, Bo; Du, Huamao; Zhang, Xuejun C; Xu, Jianguo; Li, Xuemei; Rao, Zihe

    2010-01-01

    Cholesterol-dependent cytolysins (CDC) are pore forming toxins. A prototype of the CDC family members is perfringolysin O (PFO), which directly binds to the cell membrane enriched in cholesterol, causing cell lysis. However, an exception of this general observation is intermedilysin (ILY) of Streptococcus intermedius, which requires human CD59 as a receptor in addition to cholesterol for its hemolytic activity. A possible explanation of this functional difference is the conformational variation between the C-terminal domains of the two toxins, particularly in the highly conserved undecapeptide termed tryptophan rich motif. Here, we present the crystal structure of suilysin, a CDC toxin from the infectious swine pathogen Streptococcus suis. Like PFO, suilysin does not require a host receptor for hemolytic activity; yet the crystal structure of suilysin exhibits a similar conformation in the tryptophan rich motif to ILY. This observation suggests that the current view of the structure-function relationship between CDC proteins and membrane association is far from complete.

  2. Determination of organic crystal structures by X ray powder diffraction

    CERN Document Server

    McBride, L

    2000-01-01

    The crystal structure of Ibuprofen has been solved from synchrotron X-ray powder diffraction data using a genetic algorithm (GA). The performance of the GA is improved by incorporating prior chemical information in the form of hard limits on the values that can be taken by the flexible torsion angles within the molecule. Powder X-ray diffraction data were collected for the anti-convulsant compounds remacemide, remacemide nitrate and remacemide acetate at 130 K on BM 16 at the X-ray European Synchrotron Radiation Facility (ESRF) at Grenoble. High quality crystal structures were obtained using data collected to a resolution of typically 1.5 A. The structure determinations were performed using a simulated annealing (SA) method and constrained Rietveld refinements for the structures converged to chi sup 2 values of 1.64, 1.84 and 1.76 for the free base, nitrate and acetate respectively. The previously unknown crystal structure of the drug famotidine Form B has been solved using X-ray powder diffraction data colle...

  3. Structural engineering of three-dimensional phononic crystals

    Science.gov (United States)

    Delpero, Tommaso; Schoenwald, Stefan; Zemp, Armin; Bergamini, Andrea

    2016-02-01

    Artificially-structured materials are attracting the research interest of a growing community of scientists for the possibility to develop novel materials with advantageous properties that arise from the ability to tailor the propagation of elastic waves, and thus energy, through them. In this work, we propose a three-dimensional phononic crystal whose unit cell has been engineered to obtain a strong wave-attenuation band in the middle of the acoustic frequency range. The combination of its acoustic properties with the dimensions of the unit cell and its static mechanical properties makes it an interesting material for possibly several applications in civil and mechanical engineering, for instance as the core of an acoustically insulating sandwich panel. A sample of this crystal has been manufactured and experimentally tested with respect to its acoustic transmissibility. The performance of the phononic crystal core is remarkable both in terms of amplitude reduction in the transmissibility and width of the attenuation band. A parametric study has been finally conducted on selected geometrical parameters of the unit cell and on their effect on the macroscopic properties of the crystal. This work represents an application-oriented example of how the macroscopic properties of an artificially-structured material can be designed, according to specific needs, by a conventional engineering of its unit cell.

  4. One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2016-11-01

    Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.

  5. Crystal structure of hexagonal RE(CO{sub 3})OH

    Energy Technology Data Exchange (ETDEWEB)

    Michiba, Kiyonori; Tahara, Takeshi; Nakai, Izumi [Tokyo Univ. of Science, Shinjuku (Japan). Faculty of Science; Miyawaki, Ritsuro; Matsubara, Satoshi [National Museum of Nature and Science, Tokyo (Japan). Dept. of Geology and Paleontology

    2011-07-01

    Hexagonal rare earth carbonate hydroxides, RE(CO{sub 3})OH, where RE = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er, were hydrothermally synthesized from formic acid and hydroxide gels of rare earth elements. The crystals exhibited bicephalous hexagonal prisms with lengths of several tens of micrometers. The crystal structures of a series of hexagonal RE(CO{sub 3})OH were solved using the single crystal CCD-XRD intensity data sets. The space groups of the synthetic hexagonal RE(CO{sub 3})OH crystals are all P- anti 6. The present study has cast doubt upon the space group P- anti 62c previously reported for the natural Ce(CO{sub 3})OH, hydroxylbastnaesite-(Ce). The cell parameters decreased linearly with decreases in the ionic radii of the rare earth elements. La(CO{sub 3})OH showed the largest unit cell (a = 12.6752(6), c = 10.0806(10) A), while Er(CO{sub 3})OH showed the smallest (a = 11.8977(4), c = 9.6978(8) A). The rare earth atoms are in ninefold coordination with oxygen atoms to form a tricapped trigonal prism. The structure consists of layers of {sup 2}{infinity}[(OH)RE{sub 3/3}]{sup 2+} ions linked by carbonate ions. Raman spectra indicate the presence of carbonate and hydroxide groups. An evolutionary shift was observed from La to Er towards higher frequency, which was associated with a decreasing RE-O bond length. (orig.)

  6. Photonic crystal type structure in bivalve ligament of Pinctada maxima

    Institute of Scientific and Technical Information of China (English)

    ZHANG GangSheng

    2007-01-01

    The dry ligament of Pinctada maxima normally appears black; however, it can exhibit striking blue structural colors after being wetted by water. The field-mission SEM investigation shows that the ligament is made of lamellae, which, about 35 μm thick, are made of proteins and aragonite fibers of about 78 nm in diameter. In each single lamella, the fibers are highly aligned characterized by a 2D photonic crystal type structure. According to measured reflective spectra and theoretical simulations, the dry and wet ligaments possess photonic stop band at ultraviolet and blue wavelengths, respectively, which are responsible for structural colorations of ligament.

  7. Crystal structure of inactive form of Rab3B

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Shen, Yang; Jiao, Ronghong; Liu, Yanli; Deng, Lingfu; Qi, Chao (Hebei); (Toronto); (Huazhong)

    2012-06-28

    Rab proteins are the largest family of ras-related GTPases in eukaryotic cells. They act as directional molecular switches at membrane trafficking, including vesicle budding, cargo sorting, transport, tethering, and fusion. Here, we generated and crystallized the Rab3B:GDP complex. The structure of the complex was solved to 1.9 {angstrom} resolution and the structural base comparison with other Rab3 members provides a structural basis for the GDP/GTP switch in controlling the activity of small GTPase. The comparison of charge distribution among the members of Rab3 also indicates their different roles in vesicular trafficking.

  8. Crystal structure of four-stranded Oxytricha telomeric DNA

    Science.gov (United States)

    Kang, C.; Zhang, X.; Ratliff, R.; Moyzis, R.; Rich, A.

    1992-01-01

    The sequence d(GGGGTTTTGGGG) from the 3' overhang of the Oxytricha telomere has been crystallized and its three-dimensional structure solved to 2.5 A resolution. The oligonucleotide forms hairpins, two of which join to make a four-stranded helical structure with the loops containing four thymine residues at either end. The guanine residues are held together by cyclic hydrogen bonding and an ion is located in the centre. The four guanine residues in each segment have a glycosyl conformation that alternates between anti and syn. There are two four-stranded molecules in the asymmetric unit showing that the structure has some intrinsic flexibility.

  9. Improved switching using Fano resonances in photonic crystal structures

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Kristensen, Philip Trøst; Elesin, Yuriy;

    2013-01-01

    We present a simple and robust structure for realizing asymmetric Fano transmission characteristics in photonic crystal waveguide-cavity structures. The use of Fano resonances for optical switching is analyzed using temporal coupled mode theory in combination with three-dimensional finite...... difference time domain simulations taking into account the signal bandwidth. The results suggest a significant energy reduction by employing Fano resonances compared to more well established Lorentzian resonance structures. A specific example of a Kerr nonlinearity shows an order of magnitude energy...

  10. Crystal structure optimisation using an auxiliary equation of state.

    Science.gov (United States)

    Jackson, Adam J; Skelton, Jonathan M; Hendon, Christopher H; Butler, Keith T; Walsh, Aron

    2015-11-14

    Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy-volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular, for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other "beyond" density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS, and ZnTe using nine density functionals and applied to the quaternary semiconductor Cu2ZnSnS4 and the magnetic metal-organic framework HKUST-1.

  11. Crystal structure optimisation using an auxiliary equation of state

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Adam J.; Skelton, Jonathan M.; Hendon, Christopher H.; Butler, Keith T. [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Walsh, Aron, E-mail: a.walsh@bath.ac.uk [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Global E" 3 Institute and Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2015-11-14

    Standard procedures for local crystal-structure optimisation involve numerous energy and force calculations. It is common to calculate an energy–volume curve, fitting an equation of state around the equilibrium cell volume. This is a computationally intensive process, in particular, for low-symmetry crystal structures where each isochoric optimisation involves energy minimisation over many degrees of freedom. Such procedures can be prohibitive for non-local exchange-correlation functionals or other “beyond” density functional theory electronic structure techniques, particularly where analytical gradients are not available. We present a simple approach for efficient optimisation of crystal structures based on a known equation of state. The equilibrium volume can be predicted from one single-point calculation and refined with successive calculations if required. The approach is validated for PbS, PbTe, ZnS, and ZnTe using nine density functionals and applied to the quaternary semiconductor Cu{sub 2}ZnSnS{sub 4} and the magnetic metal-organic framework HKUST-1.

  12. Isolation and Crystal Structure of Xanthones from Swertia Chirayita

    Institute of Scientific and Technical Information of China (English)

    史高峰; 鲁润华; 杨云裳; 李春雷; 杨爱梅; 蔡立祥

    2004-01-01

    In order to study the relationship between biological and pharmacological activities with their structures, a series of tri- and tetra-oxygenated xanthones including 1-hydroxyl-2,3,4,7- tetramethoxy xanthone 1, 1-hydroxyl-2,3,4,5-tetramethoxyl xanthone 2, 1-hydroxyl-3,5-dimethoxy- xanthone 3, 1,8-dihydroxyl-3,5-dimethoxyl xanthone 4 and 1,5,8-trihydroxyl-3-methoxy xanthone 5 have been isolated from Swertia chirayita. Their structures were established on the basis of spectral and chemical evidences. The crystal structure of 5 was also investigated by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic system, space group Pī with a = 7.1540(10), b = 7.520(2), c = 10.671(2) (A), V = 562.7(2) (A)3 , α = 86.50(3), β = 80.06(3) , γ = 85.00(3)°, Z = 2, Dc = 1.618 g/m3, R = 0.0405, wR = 0.1028 and F(000) = 284. The molecular structure of 5 is nearly planar and four substituents are much closer to the plane. Compound 5 contains three intermolecular hydro- gen bonds. A recent study shows that phenolic hydroxyls in xanthones are the main active groups capable of scavenging ·OH and O2·.

  13. The crystal structure of synthetic kutinaite, Cu14Ag6As7

    DEFF Research Database (Denmark)

    Karanovic, Ljiljana; Poleti, Dejan; Makovicky, Emil;

    2002-01-01

    kutinaite, X-ray diffraction, powder method, crystal structure, icosahedral alloy, arsenide, metal clusters......kutinaite, X-ray diffraction, powder method, crystal structure, icosahedral alloy, arsenide, metal clusters...

  14. 'Weird' crystal structures of elements at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Kolobyanina, Tat' yana N [L.F. Vereshchagin Institute of High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

    2002-12-31

    New crystal structures, in particular incommensurate composite crystals, discovered in the high-pressure phases of Group I, II, IV, and V elements are described, and their intermetallic and other binary structural analogs are discussed. (reviews of topical problems)

  15. How evolutionary crystal structure prediction works--and why.

    Science.gov (United States)

    Oganov, Artem R; Lyakhov, Andriy O; Valle, Mario

    2011-03-15

    Once the crystal structure of a chemical substance is known, many properties can be predicted reliably and routinely. Therefore if researchers could predict the crystal structure of a material before it is synthesized, they could significantly accelerate the discovery of new materials. In addition, the ability to predict crystal structures at arbitrary conditions of pressure and temperature is invaluable for the study of matter at extreme conditions, where experiments are difficult. Crystal structure prediction (CSP), the problem of finding the most stable arrangement of atoms given only the chemical composition, has long remained a major unsolved scientific problem. Two problems are entangled here: search, the efficient exploration of the multidimensional energy landscape, and ranking, the correct calculation of relative energies. For organic crystals, which contain a few molecules in the unit cell, search can be quite simple as long as a researcher does not need to include many possible isomers or conformations of the molecules; therefore ranking becomes the main challenge. For inorganic crystals, quantum mechanical methods often provide correct relative energies, making search the most critical problem. Recent developments provide useful practical methods for solving the search problem to a considerable extent. One can use simulated annealing, metadynamics, random sampling, basin hopping, minima hopping, and data mining. Genetic algorithms have been applied to crystals since 1995, but with limited success, which necessitated the development of a very different evolutionary algorithm. This Account reviews CSP using one of the major techniques, the hybrid evolutionary algorithm USPEX (Universal Structure Predictor: Evolutionary Xtallography). Using recent developments in the theory of energy landscapes, we unravel the reasons evolutionary techniques work for CSP and point out their limitations. We demonstrate that the energy landscapes of chemical systems have an

  16. Crystal structure of Pb3(IO4(OH22

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2014-07-01

    Full Text Available The structure of the title compound, trilead(II bis[dihydroxidotetraoxidoiodate(VII], was determined from a crystal twinned by non-merohedry with two twin domains present [twin fraction 0.73 (1:0.27 (1]. It contains three Pb2+ cations and two IO4(OH23− anions in the asymmetric unit. Each of the Pb2+ cations is surrounded by eight O atoms (cut-off value = 3.1 Å in the form of a distorted polyhedron. The octahedral IO4(OH23− anions are arranged in rows extending parallel to [021], forming a distorted hexagonal rod packing. The cations and anions are linked into a framework structure. Although H-atom positions could not be located, O...O distances suggest medium-strength hydrogen-bonding interactions between the IO4(OH2 octahedra, further consolidating the crystal packing.

  17. Solid State Synthesis and Crystal Structure of K3SI

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhen-Qian; LIU Xi; CHEN Wen-Tong; LI Yan; WU A-Qing; ZENG Hui-Yi; GUO Guo-Cong; HUANG Jin-Shun

    2006-01-01

    A new ternary alkali metal chalcogenide halide, K3SI, has been synthesized by solid state reaction method and structurally characterized by X-ray crystallography. The crystal belongs to hexagonal, space group P63cm with a = 11.699(1), c = 5.8279(9) (A), Mr = 276.26, V = 690.8(1)(A)3, Z = 6, Dc = 3.985 g/cm3, F(000) = 756, μ= 9.913 mm-1, S = 1.004, R = 0.0719 and wR = 0.2204. The title compound is the first example containing S anion in the ternary alkali metal chalcogenide halides family M3QX (M = alkali metal, Q = chalcogenide, X = halide), which crystallizes in the hexagonal anti-perovskite structure type.

  18. Crystal structure of tris-(hydroxyl-ammonium) orthophosphate.

    Science.gov (United States)

    Leinemann, Malte; Jess, Inke; Boeckmann, Jan; Näther, Christian

    2015-11-01

    The crystal structure of the title salt, ([H3NOH](+))3·[PO4](3-), consists of discrete hydroxyl-ammonium cations and ortho-phos-phate anions. The atoms of the cation occupy general positions, whereas the anion is located on a threefold rotation axis that runs through the phospho-rus atom and one of the phosphate O atoms. In the crystal structure, cations and anions are linked by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional network. Altogether, one very strong O-H⋯O, two N-H⋯O hydrogen bonds of medium strength and two weaker bifurcated N-H⋯O inter-actions are observed.

  19. Crystal Structure of the Human Laminin Receptor Precursor

    Energy Technology Data Exchange (ETDEWEB)

    Jamieson,K.; Wu, J.; Hubbard, S.; Meruelo, D.

    2008-01-01

    The human laminin receptor (LamR) interacts with many ligands, including laminin, prions, Sindbis virus, and the polyphenol (-)-epigallocatechin-3-gallate (EGCG), and has been implicated in a number of diseases. LamR is overexpressed on tumor cells, and targeting LamR elicits anti-cancer effects. Here, we report the crystal structure of human LamR, which provides insights into its function and should facilitate the design of novel therapeutics targeting LamR.

  20. Crystal structure of dichloridobis(dimethyl N-cyanodithioiminocarbonatezinc

    Directory of Open Access Journals (Sweden)

    Mouhamadou Birame Diop

    2016-03-01

    Full Text Available The ZnII atom in the title complex, [ZnCl2(C4H6N2S22], is coordinated in a distorted tetrahedral manner by two Cl atoms and two terminal N atoms of two dimethyl N-cyanodithioiminocarbonate ligands. In the crystal, the complex molecules are connected through C—H...Cl hydrogen bonds and Cl...S contacts, leading to a two-dimensional structure extending parallel to the ab plane.

  1. Dispersion Based Photonic-Crystal Structures for RF Applications

    Science.gov (United States)

    2006-06-01

    dimensional FDTD simulation. In our experiment, we fabricated the device using a computer numerically controlled ( CNC ) router . A tapered planar structure is...millimeter-wave photonic crystals are fabricated in Rexolite slabs by a computer numerically controlled ( CNC ) micro-milling system. Using the millimeter...loss, and low cost. In particular, it can be fabricated using a CNC micro-milling machine. Also, its low index provides a weaker confinement in the

  2. Programmatic conversion of crystal structures into 3D printable files using Jmol

    OpenAIRE

    Scalfani, Vincent F.; Williams, Antony J.; Tkachenko, Valery; Karapetyan, Karen; Pshenichnov, Alexey; Hanson, Robert M; Liddie, Jahred M.; Bara, Jason E.

    2016-01-01

    Background Three-dimensional (3D) printed crystal structures are useful for chemistry teaching and research. Current manual methods of converting crystal structures into 3D printable files are time-consuming and tedious. To overcome this limitation, we developed a programmatic method that allows for facile conversion of thousands of crystal structures directly into 3D printable files. Results A collection of over 30,000 crystal structures in crystallographic information file (CIF) format from...

  3. Crystal Structures of Aedes Aegypt Alanine Glyoxylate Aminotransferase

    Energy Technology Data Exchange (ETDEWEB)

    Han,Q.; Robinson, H.; Gao, Y.; Vogelaar, N.; Wilson, S.; Rizzi, M.; Li, J.

    2006-01-01

    Mosquitoes are unique in having evolved two alanine glyoxylate aminotransferases (AGTs). One is 3-hydroxykynurenine transaminase (HKT), which is primarily responsible for catalyzing the transamination of 3-hydroxykynurenine (3-HK) to xanthurenic acid (XA). Interestingly, XA is used by malaria parasites as a chemical trigger for their development within the mosquito. This 3-HK to XA conversion is considered the major mechanism mosquitoes use to detoxify the chemically reactive and potentially toxic 3-HK. The other AGT is a typical dipteran insect AGT and is specific for converting glyoxylic acid to glycine. Here we report the 1.75{angstrom} high-resolution three-dimensional crystal structure of AGT from the mosquito Aedes aegypti (AeAGT) and structures of its complexes with reactants glyoxylic acid and alanine at 1.75 and 2.1{angstrom} resolution, respectively. This is the first time that the three-dimensional crystal structures of an AGT with its amino acceptor, glyoxylic acid, and amino donor, alanine, have been determined. The protein is dimeric and adopts the type I-fold of pyridoxal 5-phosphate (PLP)-dependent aminotransferases. The PLP co-factor is covalently bound to the active site in the crystal structure, and its binding site is similar to those of other AGTs. The comparison of the AeAGT-glyoxylic acid structure with other AGT structures revealed that these glyoxylic acid binding residues are conserved in most AGTs. Comparison of the AeAGT-alanine structure with that of the Anopheles HKT-inhibitor complex suggests that a Ser-Asn-Phe motif in the latter may be responsible for the substrate specificity of HKT enzymes for 3-HK.

  4. Crystal structures of Aedes aegypti alanine glyoxylate aminotransferase.

    Science.gov (United States)

    Han, Qian; Robinson, Howard; Gao, Yi Gui; Vogelaar, Nancy; Wilson, Scott R; Rizzi, Menico; Li, Jianyong

    2006-12-01

    Mosquitoes are unique in having evolved two alanine glyoxylate aminotransferases (AGTs). One is 3-hydroxykynurenine transaminase (HKT), which is primarily responsible for catalyzing the transamination of 3-hydroxykynurenine (3-HK) to xanthurenic acid (XA). Interestingly, XA is used by malaria parasites as a chemical trigger for their development within the mosquito. This 3-HK to XA conversion is considered the major mechanism mosquitoes use to detoxify the chemically reactive and potentially toxic 3-HK. The other AGT is a typical dipteran insect AGT and is specific for converting glyoxylic acid to glycine. Here we report the 1.75A high-resolution three-dimensional crystal structure of AGT from the mosquito Aedes aegypti (AeAGT) and structures of its complexes with reactants glyoxylic acid and alanine at 1.75 and 2.1A resolution, respectively. This is the first time that the three-dimensional crystal structures of an AGT with its amino acceptor, glyoxylic acid, and amino donor, alanine, have been determined. The protein is dimeric and adopts the type I-fold of pyridoxal 5-phosphate (PLP)-dependent aminotransferases. The PLP co-factor is covalently bound to the active site in the crystal structure, and its binding site is similar to those of other AGTs. The comparison of the AeAGT-glyoxylic acid structure with other AGT structures revealed that these glyoxylic acid binding residues are conserved in most AGTs. Comparison of the AeAGT-alanine structure with that of the Anopheles HKT-inhibitor complex suggests that a Ser-Asn-Phe motif in the latter may be responsible for the substrate specificity of HKT enzymes for 3-HK.

  5. Structural considerations on acridine/acridinium derivatives: Synthesis, crystal structure, Hirshfeld surface analysis and computational studies

    Science.gov (United States)

    Wera, Michał; Storoniak, Piotr; Serdiuk, Illia E.; Zadykowicz, Beata

    2016-02-01

    This article describes a detailed study of the molecular packing and intermolecular interactions in crystals of four derivatives of acridine, i.e. 9-methyl-, 9-ethyl, 9-bromomethyl- and 9-piperidineacridine (1, 2, 3 and 4, respectively) and three 10-methylacridinium salts containing the trifluoromethanesulphonate anion and 9-vinyl-, 9-bromomethyl, and 9-phenyl-10-methylacridinium cations (5, 6 and 7, respectively). The crystal structures of all of the compounds are stabilized by long-range electrostatic interactions, as well as by a network of short-range C-HṡṡṡO (in hydrates and salts 3 and 5-7, respectively), C-Hṡṡṡπ, π-π, C-Fṡṡṡπ and S-Oṡṡṡπ (in salts 5-7) interactions. Hirshfeld surface analysis shows that various intermolecular contacts play an important role in the crystal packing, graphically exhibiting the differences in spatial arrangements of the acridine/acridinium derivatives under scrutiny here. Additionally, computational methods have been used to compare the intermolecular interactions in the crystal structures of the investigated compounds. Computations have confirmed the great contribution of dispersive interactions for crystal lattice stability in the case of 9-substituted acridine and electrostatic interactions for the crystal lattice stability in the case of 9-substituted 10-methylacridinium trifluoromethanesulphonates. The value of crystal lattice energy and the electrostatic contribution in the crystal lattice energy of monohydrated acridine derivatives have confirmed that these compounds have behave as acridinium derivatives.

  6. Crystal structure of lead(II tartrate: a redetermination

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2015-01-01

    Full Text Available Single crystals of poly[μ4-tartrato-κ6O1,O3:O1′:O2,O4:O4′-lead], [Pb(C4H4O6]n, were grown in a gel medium. In comparison with the previous structure determination of this compound from laboratory powder X-ray diffraction data [De Ridder et al. (2002. Acta Cryst. C58, m596–m598], the redetermination on the basis of single-crystal data reveals the absolute structure, all atoms with anisotropic displacement parameters and a much higher accuracy in terms of bond lengths and angles. It could be shown that a different space group or incorporation of water as reported for similarly gel-grown lead tartrate crystals is incorrect. In the structure, each Pb2+ cation is bonded to eight O atoms of five tartrate anions, while each tartrate anion links four Pb2+ cations. The resulting three-dimensional framework is stabilized by O—H...O hydrogen bonds between the OH groups of one tartrate anion and the carboxylate O atoms of adjacent anions.

  7. Pressure effects on crystal and electronic structure of bismuth tellurohalides

    Science.gov (United States)

    Rusinov, I. P.; Menshchikova, T. V.; Sklyadneva, I. Yu; Heid, R.; Bohnen, K.-P.; Chulkov, E. V.

    2016-11-01

    We study the possibility of pressure-induced transitions from a normal semiconductor to a topological insulator (TI) in bismuth tellurohalides using density functional theory and tight-binding method. In BiTeI this transition is realized through the formation of an intermediate phase, a Weyl semimetal, that leads to modification of surface state dispersions. In the topologically trivial phase, the surface states exhibit a Bychkov-Rashba type dispersion. The Weyl semimetal phase exists in a narrow pressure interval of 0.2 GPa. After the Weyl semimetal-TI transition occurs, the surface electronic structure is characterized by gapless states with linear dispersion. The peculiarities of the surface states modification under pressure depend on the band-bending effect. We have also calculated the frequencies of Raman active modes for BiTeI in the proposed high-pressure crystal phases in order to compare them with available experimental data. Unlike BiTeI, in BiTeBr and BiTeCl the topological phase transition does not occur. In BiTeBr, the crystal structure changes with pressure but the phase remains a trivial one. However, the transition appears to be possible if the low-pressure crystal structure is retained. In BiTeCl under pressure, the topological phase does not appear up to 18 GPa due to a relatively large band gap width in this compound.

  8. Nanoconfinement-induced structures in chiral liquid crystals.

    Science.gov (United States)

    Melle, Michael; Theile, Madlona; Hall, Carol K; Schoen, Martin

    2013-08-28

    We employ Monte Carlo simulations in a specialized isothermal-isobaric and in the grand canonical ensemble to study structure formation in chiral liquid crystals as a function of molecular chirality. Our model potential consists of a simple Lennard-Jones potential, where the attractive contribution has been modified to represent the orientation dependence of the interaction between a pair of chiral liquid-crystal molecules. The liquid crystal is confined between a pair of planar and atomically smooth substrates onto which molecules are anchored in a hybrid fashion. Hybrid anchoring allows for the formation of helical structures in the direction perpendicular to the substrate plane without exposing the helix to spurious strains. At low chirality, we observe a cholesteric phase, which is transformed into a blue phase at higher chirality. More specifically, by studying the unit cell and the spatial arrangement of disclination lines, this blue phase can be established as blue phase II. If the distance between the confining substrates and molecular chirality are chosen properly, we see a third structure, which may be thought of as a hybrid, exhibiting mixed features of a cholesteric and a blue phase.

  9. Nanoconfinement-Induced Structures in Chiral Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Carol K. Hall

    2013-08-01

    Full Text Available We employ Monte Carlo simulations in a specialized isothermal-isobaric and in the grand canonical ensemble to study structure formation in chiral liquid crystals as a function of molecular chirality. Our model potential consists of a simple Lennard-Jones potential, where the attractive contribution has been modified to represent the orientation dependence of the interaction between a pair of chiral liquid-crystal molecules. The liquid crystal is confined between a pair of planar and atomically smooth substrates onto which molecules are anchored in a hybrid fashion. Hybrid anchoring allows for the formation of helical structures in the direction perpendicular to the substrate plane without exposing the helix to spurious strains. At low chirality, we observe a cholesteric phase, which is transformed into a blue phase at higher chirality. More specifically, by studying the unit cell and the spatial arrangement of disclination lines, this blue phase can be established as blue phase II. If the distance between the confining substrates and molecular chirality are chosen properly, we see a third structure, which may be thought of as a hybrid, exhibiting mixed features of a cholesteric and a blue phase.

  10. Crystal structural studies of destripeptide (B28-B30) insulin

    Institute of Scientific and Technical Information of China (English)

    叶军; 茅毓新; 桂璐璐; 常文瑞; 梁栋材

    2000-01-01

    Single crystals of destripeptide (B28-B30) insulin (DTRI) in three forms were obtained by hanging-drop vapor diffusion method. Form 1 belongs to P21 space group with cell parameters a-4.77 nm, b=6.19 nm, c=6.12 nm, β=110.3°. Form 2 belongs to P4122 or P4322 space group with cell parameters a= 6.45 nm, c=12.07 nm. Form 3 belongs to P212121 space group with cell parameters a=4.98 nm, b=5.16 nm, c=10.06 nm. The structure of form 1 crystal was determined by molecular replacement method and refined at 0.23 nm resolution. The R-factor of the final model is 18.8% with r.m.s. deviations of 0.001 5 nm and 3.3?for the bond lengths and the bond angles, respectively. Studies on the crystal structure show that the removal of B28 Pro has brought DTRI structural changes which made it dissociate more easily than native insulin although DTRI can still form a hexamer.

  11. Crystal structure of lead(II) tartrate: a redetermination.

    Science.gov (United States)

    Weil, Matthias

    2015-01-01

    Single crystals of poly[μ4-tartrato-κ(6) O (1),O (3):O (1'):O (2),O (4):O (4')-lead], [Pb(C4H4O6)] n , were grown in a gel medium. In comparison with the previous structure determination of this compound from laboratory powder X-ray diffraction data [De Ridder et al. (2002 ▶). Acta Cryst. C58, m596-m598], the redetermination on the basis of single-crystal data reveals the absolute structure, all atoms with anisotropic displacement parameters and a much higher accuracy in terms of bond lengths and angles. It could be shown that a different space group or incorporation of water as reported for similarly gel-grown lead tartrate crystals is incorrect. In the structure, each Pb(2+) cation is bonded to eight O atoms of five tartrate anions, while each tartrate anion links four Pb(2+) cations. The resulting three-dimensional framework is stabilized by O-H⋯O hydrogen bonds between the OH groups of one tartrate anion and the carboxyl-ate O atoms of adjacent anions.

  12. A novel characterization of organic molecular crystal structures for the purpose of crystal engineering.

    Science.gov (United States)

    Thomas, Noel W

    2015-08-01

    A novel analytical approach is proposed for the characterization of organic molecular crystal structures where close packing is an important factor. It requires the identification of a unique reference axis within the crystal, along which three-dimensional space is divided into close-packed blocks (CPB) and junction zones (JZ). The degree of close packing along the reference axis is quantified by a two-dimensional packing function, ϕ2D, of symmetry determined by the space group. Values of ϕ2D reflect the degree of area-filling in planes perpendicular to this axis. The requirement of close packing within CPB allows the planar structures perpendicular to the reference axis to be analysed as tessellations of area-filling molecular-based cells (MBC), which are generally hexagonal. The form of these cells reflects the molecular shape in the cross-section, since their vertices are given by the centres of the voids between molecules. There are two basic types of MBC, Type 1, of glide or pseudo-glide symmetry, and Type 2, which is formed by lattice translations alone and generally requires a short unit-cell axis. MBC at layers of special symmetry are used to characterize the structures in terms of equivalent ellipses with parameters aell, bell and χell. The ratio aell/bell allows the established α, β, γ classification to be integrated into the current framework. The values of parameters aell and bell arising from all the structures considered, polynuclear aromatic hydrocarbons (PAH), substituted anthracenes and anthraquinones (SAA) and 2-benzyl-5-benzylidene (BBCP) are mapped onto a universal curve. The division of three-dimensional space into CPB and JZ is fundamentally useful for crystal engineering, since the structural perturbations brought about by substitution at hydrogen positions located within JZ are minimal. A contribution is also made to ongoing debate concerning the adoption of polar space groups, isomorphism and polymorphism.

  13. Ab initio molecular crystal structures, spectra, and phase diagrams.

    Science.gov (United States)

    Hirata, So; Gilliard, Kandis; He, Xiao; Li, Jinjin; Sode, Olaseni

    2014-09-16

    Conspectus Molecular crystals are chemists' solids in the sense that their structures and properties can be understood in terms of those of the constituent molecules merely perturbed by a crystalline environment. They form a large and important class of solids including ices of atmospheric species, drugs, explosives, and even some organic optoelectronic materials and supramolecular assemblies. Recently, surprisingly simple yet extremely efficient, versatile, easily implemented, and systematically accurate electronic structure methods for molecular crystals have been developed. The methods, collectively referred to as the embedded-fragment scheme, divide a crystal into monomers and overlapping dimers and apply modern molecular electronic structure methods and software to these fragments of the crystal that are embedded in a self-consistently determined crystalline electrostatic field. They enable facile applications of accurate but otherwise prohibitively expensive ab initio molecular orbital theories such as Møller-Plesset perturbation and coupled-cluster theories to a broad range of properties of solids such as internal energies, enthalpies, structures, equation of state, phonon dispersion curves and density of states, infrared and Raman spectra (including band intensities and sometimes anharmonic effects), inelastic neutron scattering spectra, heat capacities, Gibbs energies, and phase diagrams, while accounting for many-body electrostatic (namely, induction or polarization) effects as well as two-body exchange and dispersion interactions from first principles. They can fundamentally alter the role of computing in the studies of molecular crystals in the same way ab initio molecular orbital theories have transformed research practices in gas-phase physical chemistry and synthetic chemistry in the last half century. In this Account, after a brief summary of formalisms and algorithms, we discuss applications of these methods performed in our group as compelling

  14. Fourier transform infrared transmission microspectroscopy of photonic crystal structures.

    Science.gov (United States)

    Kilby, Gregory R; Gaylord, Thomas K

    2009-07-01

    The detailed microscopic characterization of photonic crystal (PC) structures is challenging due to their small sizes. Generally, only the gross macroscopic behavior can be determined. This leaves in question the performance at the basic structure level. The single-incident-angle plane-wave transmittances of one-dimensional photonic crystal (PC) structures are extracted from multiple-incident-angle, focused-beam measurements. In the experimental apparatus, an infrared beam is focused by a reflecting microscope objective to produce an incident beam. This beam can be modeled as multiple, variable-intensity plane waves incident on the PC structure. The transmittance of the structure in response to a multiple-incident-angle composite beam is measured. The composite beam measurement is repeated at various incident angle orientations with respect to the sample normal so that, at each angular orientation, the included set of single-angle plane-wave components is unique. A set of measurements recorded over a range of angular orientations results in an underspecified matrix algebra problem. Regularization techniques can be applied to the problem to extract the single-angle plane-wave response of the structure from the composite measurements. Experimental results show very good agreement between the measured and theoretical single-angle plane-wave transmittances.

  15. Crystal structure of inactive form of Rab3B

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Shen, Yang [Structural Genomics Consortium, University of Toronto, 101 College St., Toronto, Ontario, Canada M5G 1L7 (Canada); Jiao, Ronghong [Department of Function Inspection, Hebei Provincial People' s Hospital, Shijiazhuang 050051 (China); Liu, Yanli; Deng, Lingfu [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Qi, Chao, E-mail: qichao@mail.ccnu.edu.cn [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer This is the first structural information of human Rab3B. Black-Right-Pointing-Pointer To provides a structural basis for the GDP/GTP switch in controlling the activity of Rab3. Black-Right-Pointing-Pointer The charge distribution of Rab3B indicates its unique roles in vesicular trafficking. -- Abstract: Rab proteins are the largest family of ras-related GTPases in eukaryotic cells. They act as directional molecular switches at membrane trafficking, including vesicle budding, cargo sorting, transport, tethering, and fusion. Here, we generated and crystallized the Rab3B:GDP complex. The structure of the complex was solved to 1.9 A resolution and the structural base comparison with other Rab3 members provides a structural basis for the GDP/GTP switch in controlling the activity of small GTPase. The comparison of charge distribution among the members of Rab3 also indicates their different roles in vesicular trafficking.

  16. Effect of Crystal Growth Direction on Domain Structure of Mn-Doped (Na,K)NbO3 Crystal

    Science.gov (United States)

    Tsuchida, Kohei; Kakimoto, Ken-ichi; Kagomiya, Isao

    2013-09-01

    Single crystals of (Na0.55K0.45)(Nb0.995Mn0.005)O3 have been grown by a floating zone method in N2 and decompression atmosphere to avoid alkaline metal volatilization on the SrTiO3 material base. The variation of their ferroelectric domain structure and the chemical composition of the grown crystal in the growth direction were evaluated. In the crystal grown in N2 atmosphere, the Na and K are not distributed homogeneously. In addition, the phase transition temperature TC and TO-T showed different values between the grown crystal and raw material. By using laser scanning confocal microscope, the domain structures of the grown crystal revealed random patterns in the initial growth stage and lamellar patterns in the progressing crystal growth. In decompression atmosphere, the TC and TO-T values of the grown crystal were similar to those of the raw material and the domain structures showed a constant domain size. The electrical property of the crystal became stable and the domain structure was easily switched against applied electrical field because the oriented lamellar domain was created during cooling of the crystal.

  17. Iron-Ion Implantation into the Structure of Rock Crystal

    Directory of Open Access Journals (Sweden)

    A.V. Mukhametshin

    2017-03-01

    Full Text Available Iron ions with the energy of 40 keV have been implanted into colorless natural rock crystals to high fluencies of 1.0∙1017 and 1.5∙1017 ion/cm2. These crystals were selected from Svetlinsky deposits of the Southern Urals, which are well-known as minerals with high quality and low content of impurities. A radical change in the color of the crystals after iron-ion implantation and subsequent high-temperature annealing in air has been revealed. The origin of color changes has been studied by using optical methods, as well as Mössbauer and X-ray photoelectron spectroscopy. It has been established that the high-dose and high-energy flow of ions results in the formation of various kinds of structural defects on the surface layer of the matrix, such as electron-hole centers, as well as in the formation at a specific depth of the irradiated matrix of the ultrafine iron-containing phases with a structure, which is non-coherent to the structure of the original matrix. The subsequent high-temperature annealing of the implanted quartz has changed the color of the samples to orange-yellow. This color is similar to the color of natural citrine. The orange color richness of the heat-treated samples grew with increasing amounts of embedded iron impurity in the crystal. The nature of orange-yellow coloration of the implanted and annealed quartz plates can be explained by the formation of ultrafine hematite nanoparticles located in a layer at a depth of ~15 nm. The possibility of refining the color of minerals by ion-beam exposure has been discussed.

  18. Crystal Structure of an Ammonia-Permeable Aquaporin

    DEFF Research Database (Denmark)

    Kirscht, Andreas; Kaptan, Shreyas S; Bienert, Gerd Patrick;

    2016-01-01

    the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals...... an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity...

  19. Unified approach for determining tetragonal tungsten bronze crystal structures.

    Science.gov (United States)

    Smirnov, M; Saint-Grégoire, P

    2014-05-01

    Tetragonal tungsten bronze (TTB) oxides are one of the most important classes of ferroelectrics. Many of these framework structures undergo ferroelastic transformations related to octahedron tilting deformations. Such tilting deformations are closely related to the rigid unit modes (RUMs). This paper discusses the whole set of RUMs in an ideal TTB lattice and possible crystal structures which can emerge owing to the condensation of some of them. Analysis of available experimental data for the TTB-like niobates lends credence to the obtained theoretical predictions.

  20. Holographic liquid crystal polarization grating with Fabry-Perot structure.

    Science.gov (United States)

    Sakamoto, Moritsugu; Yamaguchi, Haruki; Noda, Kohei; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2016-03-15

    A holographic liquid crystal polarization grating with a Fabry-Perot structure was developed. Because of its resonant structure, the device offers high levels of control of the diffraction properties of incident-polarized light beams, depending on the resonance conditions. The diffracted light beams are emitted in both the reflection and transmission directions, and the device thus works as a multibranch polarization grating with double optical paths, unlike a conventional polarization grating. These device features were experimentally demonstrated and were also explained theoretically.

  1. Crystal structure of 3-bromo-2-hydroxybenzoic acid

    Directory of Open Access Journals (Sweden)

    Gerhard Laus

    2015-05-01

    Full Text Available Mutual carboxyl–carboxyl O—H...O hydrogen bonds link the molecules of the title compound, C7H5BrO3, into centrosymmetric dimers which display a central R22(8 ring motif. In addition, there is an intramolecular hydroxyl–carboxyl O—H...O interaction present. A comparison with the crystal structures of 59 other substituted derivatives of salicylic acid shows that both the centrosymmetric carboxyl–carboxyl O—H...O dimer and the stacking mode of molecules along the short a axis observed in the title structure are frequent packing motifs in this set.

  2. Fusion proteins as alternate crystallization paths to difficult structure problems

    Science.gov (United States)

    Carter, Daniel C.; Rueker, Florian; Ho, Joseph X.; Lim, Kap; Keeling, Kim; Gilliland, Gary; Ji, Xinhua

    1994-01-01

    The three-dimensional structure of a peptide fusion product with glutathione transferase from Schistosoma japonicum (SjGST) has been solved by crystallographic methods to 2.5 A resolution. Peptides or proteins can be fused to SjGST and expressed in a plasmid for rapid synthesis in Escherichia coli. Fusion proteins created by this commercial method can be purified rapidly by chromatography on immobilized glutathione. The potential utility of using SjGST fusion proteins as alternate paths to the crystallization and structure determination of proteins is demonstrated.

  3. Crystal structure of seleno-l-cystine dihydrochloride

    OpenAIRE

    Carl Henrik Görbitz; Vladimir Levchenko; Jevgenijs Semjonovs; Mohamed Yusuf Sharif

    2015-01-01

    Numerous crystal structures are available for the dimeric amino acid cystine. In proteins it is formed by oxidation of the –SH thiol groups of two closely spaced cysteine residues, resulting in the formation of a familiar disulfide bridge. The title compound [systematic name: (R,R)-1,1′-dicarboxy-2,2′-(diselanediyl)diethanaminium dichloride], C6H14N2O4Se22+·2Cl−, is the first example of a small molecule structure of the biologically important analogue with a —CH2—Se—Se—CH2— bridging unit. Bon...

  4. Band structures in the nematic elastomers phononic crystals

    Science.gov (United States)

    Yang, Shuai; Liu, Ying; Liang, Tianshu

    2017-02-01

    As one kind of new intelligent materials, nematic elastomers (NEs) represent an exciting physical system that combines the local orientational symmetry breaking and the entropic rubber elasticity, producing a number of unique physical phenomena. In this paper, the potential application of NEs in the band tuning is explored. The band structures in two kinds of NE phononic crystals (PCs) are investigated. Through changing NE intrinsic parameters, the influence of the porosity, director rotation and relaxation on the band structures in NE PCs are analyzed. This work is a meaningful try for application of NEs in acoustic field and proposes a new intelligent strategy in band turning.

  5. The Cambridge Structural Database: a quarter of a million crystal structures and rising.

    Science.gov (United States)

    Allen, Frank H

    2002-06-01

    The Cambridge Structural Database (CSD) now contains data for more than a quarter of a million small-molecule crystal structures. The information content of the CSD, together with methods for data acquisition, processing and validation, are summarized, with particular emphasis on the chemical information added by CSD editors. Nearly 80% of new structural data arrives electronically, mostly in CIF format, and the CCDC acts as the official crystal structure data depository for 51 major journals. The CCDC now maintains both a CIF archive (more than 73,000 CIFs dating from 1996), as well as the distributed binary CSD archive; the availability of data in both archives is discussed. A statistical survey of the CSD is also presented and projections concerning future accession rates indicate that the CSD will contain at least 500,000 crystal structures by the year 2010.

  6. Crystal structure and crystal chemistry of melanovanadite, a natural vanadium bronze.

    Science.gov (United States)

    Konnert, J.A.; Evans, H.T.

    1987-01-01

    The crystal structure of melanovanadite from Minas Ragra, Peru, has been determined in space group P1. The triclinic unit cell (non-standard) has a 6.360(2), b 18.090(9), c 6.276(2) A, alpha 110.18(4)o, beta 101.62(3)o, gamma 82.86(4)o. A subcell with b' = b/2 was found by crystal-structure analysis to contain CaV4O10.5H2O. The subcell has a layer structure in which the vanadate sheet consists of corner-shared tetrahedral VO4 and double square-pyramidal V2O8 groups, similar to that previously found in synthetic CsV2O5. Refinement of the full structure (R = 0.056) showed that the Ca atom, which half-occupies a general position in the subcell, is 90% ordered at one of these sites in the whole unit cell. Bond length-bond strength estimates indicate that the tetrahedra contain V5+, and the square pyramids, V4+.-J.A.Z.

  7. N-(4-Methyl-benzo-yl)-2-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Suchetan, P A; Foro, Sabine; Gowda, B Thimme

    2012-03-01

    The asymmetric unit of the title compound, C(14)H(12)N(2)O(5)S, contains two independent mol-ecules. The dihedral angles between the aromatic rings are 82.03 (9) and 79.47 (8)° in the two independent mol-ecules. In the crystal, the two mol-ecules in the asymmetric unit are linked into dimers via pairs of N-H⋯O(S) hydrogen bonds to generate C(4) chains.

  8. Crystal structure of eukaryotic ribosome and its complexes with inhibitors.

    Science.gov (United States)

    Yusupova, Gulnara; Yusupov, Marat

    2017-03-19

    A high-resolution structure of the eukaryotic ribosome has been determined and has led to increased interest in studying protein biosynthesis and regulation of biosynthesis in cells. The functional complexes of the ribosome crystals obtained from bacteria and yeast have permitted researchers to identify the precise residue positions in different states of ribosome function. This knowledge, together with electron microscopy studies, enhances our understanding of how basic ribosome processes, including mRNA decoding, peptide bond formation, mRNA, and tRNA translocation and cotranslational transport of the nascent peptide, are regulated. In this review, we discuss the crystal structure of the entire 80S ribosome from yeast, which reveals its eukaryotic-specific features, and application of X-ray crystallography of the 80S ribosome for investigation of the binding mode for distinct compounds known to inhibit or modulate the protein-translation function of the ribosome. We also refer to a challenging aspect of the structural study of ribosomes, from higher eukaryotes, where the structures of major distinctive features of higher eukaryote ribosome-the high-eukaryote-specific long ribosomal RNA segments (about 1MDa)-remain unresolved. Presently, the structures of the major part of these high-eukaryotic expansion ribosomal RNA segments still remain unresolved.This article is part of the themed issue 'Perspectives on the ribosome'.

  9. Crystal structure of the 80S yeast ribosome.

    Science.gov (United States)

    Jenner, Lasse; Melnikov, Sergey; Garreau de Loubresse, Nicolas; Ben-Shem, Adam; Iskakova, Madina; Urzhumtsev, Alexandre; Meskauskas, Arturas; Dinman, Jonathan; Yusupova, Gulnara; Yusupov, Marat

    2012-12-01

    The first X-ray structure of the eukaryotic ribosome at 3.0Å resolution was determined using ribosomes isolated and crystallized from the yeast Saccharomyces cerevisiae (Ben-Shem A, Garreau de Loubresse N, Melnikov S, Jenner L, Yusupova G, Yusupov M: The structure of the eukaryotic ribosome at 3.0 A resolution. Science 2011, 334:1524-1529). This accomplishment was possible due to progress in yeast ribosome biochemistry as well as recent advances in crystallographic methods developed for structure determination of prokaryotic ribosomes isolated from Thermus thermophilus and Escherichia coli. In this review we will focus on the development of isolation procedures that allowed structure determination (both cryo-EM and X-ray crystallography) to be successful for the yeast S. cerevisiae. Additionally we will introduce a new nomenclature that facilitates comparison of ribosomes from different species and kingdoms of life. Finally we will discuss the impact of the yeast 80S ribosome crystal structure on perspectives for future investigations.

  10. From Protein Structure to Function via Single Crystal Optical Spectroscopy

    Directory of Open Access Journals (Sweden)

    Luca eRonda

    2015-04-01

    Full Text Available The more than 100.000 protein structures determined by X-ray crystallography provide a wealth of information for the characterization of biological processes at the molecular level. However, several crystallographic artifacts, including conformational selection, crystallization conditions and radiation damages, may affect the quality and the interpretation of the electron density map, thus limiting the relevance of structure determinations. Moreover, for most of these structures no functional data have been obtained in the crystalline state, thus posing serious questions on their validity in the inference for protein mechanisms. In order to solve these issues, spectroscopic methods have been applied for the determination of equilibrium and kinetic properties of proteins in the crystalline state. These methods are UV-vis spectrophotometry, spectrofluorimetry, IR, EPR, Raman and resonance Raman spectroscopy. Some of these approaches have been implemented with on-line instruments at X-ray synchrotron beamlines. Here, we provide an overview of investigations predominantly carried out in our laboratory by single crystal polarized absorption UV-vis microspectrophotometry, the most applied technique for the functional characterization of proteins in the crystalline state. Studies on hemoglobins, pyridoxal 5’-phosphate dependent enzymes and green fluorescent protein in the crystalline state have addressed key biological issues, leading to either straightforward structure-function correlations or limitations to structure-based mechanisms.

  11. The crystal structure of human GDP-L-fucose synthase.

    Science.gov (United States)

    Zhou, Huan; Sun, Lihua; Li, Jian; Xu, Chunyan; Yu, Feng; Liu, Yahui; Ji, Chaoneng; He, Jianhua

    2013-09-01

    Human GDP-l-fucose synthase, also known as FX protein, synthesizes GDP-l-fucose from its substrate GDP-4-keto-6-deoxy-d-mannose. The reaction involves epimerization at both C-3 and C-5 followed by an NADPH-dependent reduction of the carbonyl at C-4. In this paper, the first crystal structure of human FX protein was determined at 2.37 Å resolution. The asymmetric unit of the crystal structure contains four molecules which form two homodimers. Each molecule consists of two domains, a Rossmann-fold NADPH-binding motif and a carboxyl terminal domain. Compared with the Escherichia coli GDP-l-fucose synthase, the overall structures of these two enzymes have four major differences. There are four loops in the structure of human FX protein corresponding to two α-helices and two β-sheets in that of the E. coli enzyme. Besides, there are seven different amino acid residues binding with NAPDH comparing human FX protein with that from E. coli. The structure of human FX reveals the key catalytic residues and could be useful for the design of drugs for the treatment of inflammation, auto-immune diseases, and possibly certain types of cancer.

  12. Natural Cr3+-rich ettringite: occurrence, properties, and crystal structure

    Science.gov (United States)

    Seryotkin, Yurii V.; Sokol, Ella V.; Kokh, Svetlana N.; Murashko, Mikhail N.

    2017-08-01

    Cr3+-rich ettringite with Cr3+→Al substitution and Cr/(Cr + Al) ratios up to 0.40-0.50 was found in mineral assemblages of the Ma'aleh Adumim area of Mottled Zone (Judean Desert). The Cr3+-rich compositions were the latest in the thaumasite → ettringite-thaumasite solid solution → ettringite → ettringite-bentorite solid solution series. The mineral-forming solution was enriched in Cr3+ and had a pH buffered by afwillite at 11-12. Chromium was inherited from larnite rocks produced by high-temperature combustion metamorphic alteration of bioproductive calcareous sediments. The Cr/(Cr + Al) ratios are within 0.10-0.15 in most of the analysed crystals. This degree of substitution imparts pink colouration to the crystals, but does not affect their habit (a combination of monohedra and a prism). The habit changes to pyramid faces in coarse and later Cr3+-bearing crystals as Cr/(Cr + Al) ratios increase abruptly to 0.40-0.50. Single-crystal XRD analysis of one Cr-free and two Cr3+-rich samples and their structure determination and refinement indicate that the Cr-rich crystals (with Cr/(Cr + Al) to 0.3) preserve the symmetry and metrics of ettringite. The Ca-O bonding network undergoes differentiation with increase of Cr3+ concentration at octahedral M sites. The compression of Ca2 and expansion of Ca1 polyhedra sub-networks correlates with the degree of Cr3+→Al substitution.

  13. Relation between photochromic properties and molecular structures in salicylideneaniline crystals.

    Science.gov (United States)

    Johmoto, Kohei; Ishida, Takashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

    2012-06-01

    The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

  14. Synthesis and Crystal Structure of a New Adamantane Amide Derivative

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ying-Hua; LV Qi-Chun; ZHANG Qian; CHENG Yong; SHENG En-Hong

    2012-01-01

    A novel adamantane acyl amide derivative containing two phthalimido pendant groups(C31H31N3O5) has been synthesized,and its structure was characterized by elemental analysis,IR,1 H NMR spectra,and single-crystal X-ray diffraction.The crystal belongs to triclinic,space group P1 with a=7.3158(10),b=13.2405(18),c=14.378(2),α=72.419(2),β=84.496(2),γ=81.799(2)o,V=1312.0(3)3,Z=2,Dc=1.330 g/cm 3,μ=0.09 mm-1,Mr=525.59,F(000)=556,S=1.001,R=0.0523 and wR=0.0707 for 5901 unique reflections with 2363 observed ones(I〉2σ(I)).π-π stacking interactions(offset face-to-face) exist between the two rings of phthalimides from the neighboring molecules in the title crystal structure.The intermolecular dihedral angle between the two rings of neighboring phthalic amides is 6.26° and the distance is 4.008.

  15. Crystal structure of the Fe-member of usovite

    Directory of Open Access Journals (Sweden)

    Matthias Weil

    2015-06-01

    Full Text Available Crystals of the title compound, with the idealized composition Ba2CaFeAl2F14, dibarium calcium iron(II dialuminium tetradecafluoride, were obtained serendipitously by reacting a mixture of the binary fluorides BaF2, CaF2 and AlF3 in a leaky steel reactor. The compound crystallizes in the usovite structure type (Ba2CaMgAl2F14, with Fe2+ cations replacing the Mg2+ cations. The principal building units are distorted [CaF8] square-antiprisms (point group symmetry 2, [FeF6] octahedra (point group symmetry -1 and [AlF6] octahedra that are condensed into undulating 2∞[CaFeAl2F14]4− layers parallel (100. The Ba2+ cations separate the layers and exhibit a coordination number of 12. Two crystal structure models with a different treatment of the disordered Fe site [mixed Fe/Ca occupation, model (I, versus underoccupation of Fe, model (II], are discussed, leading to different refined formulae Ba2Ca1.310 (15Fe0.690 (15Al2F14 [model (I] and Ba2CaFe0.90 (1Al2F14 [model (II].

  16. Effect of crystal packing on the structures of polymeric metallocenes.

    Science.gov (United States)

    Dinnebier, R E; van Smaalen, Sander; Olbrich, F; Carlson, S

    2005-02-21

    The pressure dependencies of the crystal structures of the polymeric metallocenes lithium cyclopentadienide (LiCp) and potassium cyclopentadienide (KCp) have been determined by synchrotron X-ray powder diffraction. The decrease of the volume of LiCp by 34% up to a pressure of p = 12.2 GPa and of KCp by 23% at p = 5.3 GPa as well as the bulk moduli of K = 7.7 GPa for LiCp and 4.9 GPa for KCp indicate a high compressibility for these compounds. The crystal structures of KCp have been determined up to p = 3.9 GPa. An increase of the bend angle is found from 45 degrees at p = 0 GPa up to 51 degrees at p = 3.9 GPa. This variation is completely explained by a model invoking attractive K+ Cp- interaction and repulsive nonbonded carbon-carbon interactions. It is proposed that the bend angle in the polymeric alkali metal metallocenes is the result of the optimization of the crystal packing.

  17. Crystal structure of dichloridobis(dimethyl N-cyanodithioiminocarbonatecobalt(II

    Directory of Open Access Journals (Sweden)

    Mouhamadou Birame Diop

    2016-01-01

    Full Text Available The structure of the mononuclear title complex, [{(H3CS2C=NC[triple-bond] N}2CoCl2], consists of a CoII atom coordinated in a distorted tetrahedral manner by two Cl− ligands and the terminal N atoms of two dimethyl N-cyanodithioiminocarbonate ligands. The two organic ligands are almost coplanar, with a dihedral angle of 5.99 (6° between their least-squares planes. The crystal packing features pairs of inversion-related complexes that are held together through C—H...Cl and C—H...S interactions and π–π stacking [centroid-to-centroid distance = 3.515 (su? Å]. Additional C—H...Cl and C—H...S interactions, as well as Cl...S contacts < 3.6 Å, consolidate the crystal packing.

  18. Crystal Structure of Ethanolamine 5-Nitrosalicylic Acid Organic Adduct

    Institute of Scientific and Technical Information of China (English)

    金轶; 车云霞; 魏荣敏; 郑吉民

    2004-01-01

    The title adduct (C18H24N4O12, Mr = 488.41) crystallizes in monoclinic, space group P21/c with a = 4.0514(19), b = 25.193(11), c = 10.751(5)(A), β = 95.070(8)o, V = 1093.0(9)(A)3, Z = 4, Dc = 1.484 g/cm3, F(000) = 512, μ(MoKα) = 1.26 cm-1, T = 293 K, the final R = 0.0593 and wR = 0.0862 for 956 observed reflections with I > 2(I). The compound is a 1:1 adduct of ethanolamine and 5-nitrosalicylic acid. The nitrogen atom of ethanolamine is protonated. In this crystal there exist a number of hydrogen bonds which link the ethanolamine and 5-nitrosalicylic acid molecules to form a three-dimensional infinite network structure.

  19. Synthesis and crystal structure of ethyl benzimidazole-2-yl phosphonate

    Institute of Scientific and Technical Information of China (English)

    HU, Fang-Zhong; WENG, Lin-Hong; YANG, Hua-Zheng; ZOU, Xiao-Mao

    2000-01-01

    When N-cyanoimido- ( O, O-diethyl ) phosphonyl/ S-methyl thiocarbonate (1) was treated with o-phenylenediamine in the presence of Et3N in ethanol, diethyl benzimidazole-2-yl recrys phonate(2) was obtained and hydrolyzed during the recrys tallization in MeOH/H2O, generating ethyl benzimidazole-2-yl phosphonate(3). The crystal structure of compound 3 was determined by X-ray diffraction method. The crystals belong to monoclinic, space rgoup C2/c, a=1.78408(18), b=O. 83725(9), c=1.67401(18) nm, β= 118.997(2)°, v=2. 1870(4) nm3, z=8, Dc=1.374g/cm3, F(000)=944.The final R and wR are 0.0499 and 0.1436, respectively. The mechanism of the above reaction is also discussed.

  20. SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF BIS-(2-HYDROXYBENZALDEHYDEDIAMINOGUANIZONE

    Directory of Open Access Journals (Sweden)

    Diana Dragancea, Vladimir B. Arion, Sergiu Shova

    2008-12-01

    Full Text Available The new ligand, bis(2-hydroxybenzaldehydediaminoguanizone (1 has been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopies. The crystal structure of the compound was determined by X-ray diffraction. The ligand C15H15N5O2·C2H5OH crystallizes in the monoclinic space group P21/c with unit cell parameters a = 8.9102(3, b = 10.0357(3, c = 19.7618(6 Å, β = 98.385(2°, Z = 4, V = 1748.21(9 Å3, R1 = 0.040. The amino form of the ligand adopts a planar conformation stabilized by two intramolecular hydrogen bonds of the type O–H···N, in which the H atoms of the central amino group are directed to the lone-pair regions of the azomethine nitrogen atoms.

  1. Crystal structure and magnetism of UOsAl

    Science.gov (United States)

    Andreev, A. V.; Daniš, S.; Šebek, J.; Henriques, M. S.; Vejpravová, J.; Gorbunov, D. I.; Havela, L.

    2017-04-01

    Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn2 type, space group P63/mmc, with lattice parameters a=536.4 pm, c=845.3 pm. Shortest inter-uranium distance 313 pm (along the c-axis) is considerably smaller than the Hill limit (340 pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10-8 m3 mol-1 (at T=2 K), which is slightly higher with magnetic field along the a-axis compared to the c-axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ=36 mJ mol-1 K-2.

  2. Morphology, crystal structure and hydration of calcined and modified anhydrite

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing Niu; Ji-chun Chen

    2014-01-01

    The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight in-crease in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 min, respectively. The com-pressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material.

  3. Crystal structures and conformers of CyMe4-BTBP

    Directory of Open Access Journals (Sweden)

    Lyczko Krzysztof

    2015-12-01

    Full Text Available The crystal structure of new conformation of the CyMe4-BTBP ligand (ttc has been presented. The ttt conformer of this compound in a form of THF solvate has been also crystallized. The geometries of six possible conformations (ttt, ttc, tct, tcc, ctc and ccc of the CyMe4-BTBP ligand have been modeled in the gas phase and in solutions (MeOH and H2O by DFT calculations using B3LYP/6-31G(d,p method. According to the calculations, in the three different media the conformers with trans orientation of the N atoms in the bipyridyl moiety are the most stable.

  4. Crystal structure of isoflavone reductase from alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Wang, Xiaoqiang; He, Xianzhi; Lin, Jianqiao; Shao, Hui; Chang, Zhenzhan; Dixon, Richard A

    2006-05-19

    Isoflavonoids play important roles in plant defense and exhibit a range of mammalian health-promoting activities. Isoflavone reductase (IFR) specifically recognizes isoflavones and catalyzes a stereospecific NADPH-dependent reduction to (3R)-isoflavanone. The crystal structure of Medicago sativa IFR with deletion of residues 39-47 has been determined at 1.6A resolution. Structural analysis, molecular modeling and docking, and comparison with the structures of other NADPH-dependent enzymes, defined the putative binding sites for co-factor and substrate and potential key residues for enzyme activity and substrate specificity. Further mutagenesis has confirmed the role of Lys144 as a catalytic residue. This study provides a structural basis for understanding the enzymatic mechanism and substrate specificity of IFRs as well as the functions of IFR-like proteins.

  5. Crystal Structure of the Japanese Encephalitis Virus Envelope Protein

    Energy Technology Data Exchange (ETDEWEB)

    Luca, Vincent C.; AbiMansour, Jad; Nelson, Christopher A.; Fremont, Daved H. (WU-MED)

    2012-03-13

    Japanese encephalitis virus (JEV) is the leading global cause of viral encephalitis. The JEV envelope protein (E) facilitates cellular attachment and membrane fusion and is the primary target of neutralizing antibodies. We have determined the 2.1-{angstrom} resolution crystal structure of the JEV E ectodomain refolded from bacterial inclusion bodies. The E protein possesses the three domains characteristic of flavivirus envelopes and epitope mapping of neutralizing antibodies onto the structure reveals determinants that correspond to the domain I lateral ridge, fusion loop, domain III lateral ridge, and domain I-II hinge. While monomeric in solution, JEV E assembles as an antiparallel dimer in the crystal lattice organized in a highly similar fashion as seen in cryo-electron microscopy models of mature flavivirus virions. The dimer interface, however, is remarkably small and lacks many of the domain II contacts observed in other flavivirus E homodimers. In addition, uniquely conserved histidines within the JEV serocomplex suggest that pH-mediated structural transitions may be aided by lateral interactions outside the dimer interface in the icosahedral virion. Our results suggest that variation in dimer structure and stability may significantly influence the assembly, receptor interaction, and uncoating of virions.

  6. Crystal structure and conformational analysis of angiotensinogen fragments.

    Science.gov (United States)

    Benkoulouche, M; Cotrait, M; Geoffre, S; Precigoux, G

    1989-12-01

    The tripeptide acetyl-L-prolyl-L-phenylalanyl-L-histidine crystallizes in the orthorhombic space group P2(1)2(1)2(1) with eight molecules in a unit cell of dimensions a = 9.028(2), b = 140.54(6) and c = 42.41(1)A. The structure has been solved by direct methods and refined to an R value of 0.056 for 2904 observed reflections. The molecule exists as a zwitterion with terminal (His)CO2- and (imidazole)H+ as charged groups. The two peptide molecules in the structure adopt a type I beta-turn with Pro and Phe as the corner residues. The main conformational difference between the two crystallographically independent molecules is seen to be in the histidine side-chain orientations. The molecules arrange themselves in sheets perpendicular to the c axis. All hydrophobic side chains lie on one side of the sheets thus generated, whereas the hydrophilic groups are located on the other side. An interesting feature of the crystal structure is the existence of a water layer between adjacent peptide sheets. The conformational study of the isolated Ac-His-Pro-Phe-His-MA using energy calculations gives a rather limited number of stable conformers. The most stable corresponds to a type I beta-turn stabilized through two hydrogen bonds, followed by a less stable type II beta-turn (delta E = 2.0 kcal) and a partly helical structure (delta E = 2.6 kcal).

  7. The optical Tamm states in a photonic-crystal Structure based on the cholesteric liquid crystal

    CERN Document Server

    Vetrov, Stepan Ya; Timofeev, Ivan V

    2015-01-01

    We investigate the localized surface modes in a structure consisting of the cholesteric liquid crystal layer, a phase plate, and a metal layer. These modes are analogous to the optical Tamm states. The anisotropy of transmission of light propagating the forward and backward directions is established. It is demonstrated that the transmission spectrum can be controlled by external fields acting on the cholesteric and by varying the plane of polarization of the incident light. [The text is presented both in English (pp 1-10) and in Russian (pp 11-20)

  8. Structure, Hydrodynamics, and Phase Transition of Freely Suspended Liquid Crystals

    Science.gov (United States)

    Clark, Noel A.

    2000-01-01

    Smectic liquid crystals are phases of rod shaped molecules organized into one dimensionally (1D) periodic arrays of layers, each layer being between one and two molecular lengths thick. In the least ordered smectic phases, the smectics A and C, each layer is a two dimensional (2D) liquid. Additionally there are a variety of more ordered smectic phases having hexatic short range translational order or 2D crystalline quasi long range translational order within the layers. The inherent fluid-layer structure and low vapor pressure of smectic liquid crystals enable the long term stabilization of freely suspended, single component, layered fluid films as thin as 30A, a single molecular layer. The layering forces the films to be an integral number of smectic layers thick, quantizing their thickness in layer units and forcing a film of a particular number of layers to be physically homogeneous with respect to its layer structure over its entire area. Optical reflectivity enables the precise determination of the number of layers. These ultrathin freely suspended liquid crystal films are structures of fundamental interest in condensed matter and fluid physics. They are the thinnest known stable condensed phase fluid structures and have the largest surface-to-volume ratio of any stable fluid preparation, making them ideal for the study of the effects of reduced dimensionality on phase behavior and on fluctuation and interface phenomena. Their low vapor pressure and quantized thickness enable the effective use of microgravity to extend the study of basic capillary phenomena to ultrathin fluid films. Freely suspended films have been a wellspring of new liquid crystal physics. They have been used to provide unique experimental conditions for the study of condensed phase transitions in two dimensions. They are the only system in which the hexatic has been unambiguously identified as a phase of matter, and the only physical system in which fluctuations of a 2D XY system and

  9. Structural chemistry and number theory amalgamized: crystal structure of Na11Hg52.

    Science.gov (United States)

    Hornfeck, Wolfgang; Hoch, Constantin

    2015-12-01

    The recently elucidated crystal structure of the technologically important amalgam Na11Hg52 is described by means of a method employing some fundamental concept of number theory, namely modular arithmetical (congruence) relations observed between a slightly idealized set of atomic coordinates. In combination with well known ideas from group theory, regarding lattice-sublattice transformations, these allow for a deeper mutual understanding of both and provide the structural chemist with a slightly different kind of spectacles, thus enabling a distinct viw on complex crystal structures in general.

  10. Bismuth zinc vanadate, BiZn2VO6 : new crystal structure type and electronic structure.

    OpenAIRE

    Nunes, Sayonara Eliziario; Wang, Chun-Hai; So, Karwei; Evans, John S. O.; Evans, Ivana Radosavljevic

    2015-01-01

    We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn2VO6, known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn2VO6 adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO4 tetrahedra, ZnO6 octahedra and VO4 tet...

  11. Study of crystal structure at high temperature phase in KIO sub 3 crystal by synchrotron powder X-ray diffraction

    CERN Document Server

    Kasatani, H; Kuroiwa, Y; Yagi, K; Katayama, R; Terauchi, H

    2003-01-01

    The accurate crystal structure of the I-phase in KIO sub 3 crystal has been obtained at 530 K, for the first time, by the MEM/Rietveld analysis from high-energy X-ray powder-diffraction data. The crystal structure of the I-phase is the rhombohedral perovskite structure (space group R3m; Z=1). The MEM charge-density distributions reveal that the shorter I-O bond exhibits a covalent bonding character and others (I-K, K-O and longer I-O bonds) an ionic.

  12. In situ proteolysis to generate crystals for structure determination: an update.

    Directory of Open Access Journals (Sweden)

    Amy Wernimont

    Full Text Available For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13-15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trials--in situ proteolysis--significantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate. Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 A resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects.

  13. Exploring Solid-State Structure and Physical Properties: A Molecular and Crystal Model Exercise

    Science.gov (United States)

    Bindel, Thomas H.

    2008-01-01

    A crystal model laboratory exercise is presented that allows students to examine relations among the microscopic-macroscopic-symbolic levels, using crystalline mineral samples and corresponding crystal models. Students explore the relationship between solid-state structure and crystal form. Other structure-property relationships are explored. The…

  14. Exploring Solid-State Structure and Physical Properties: A Molecular and Crystal Model Exercise

    Science.gov (United States)

    Bindel, Thomas H.

    2008-01-01

    A crystal model laboratory exercise is presented that allows students to examine relations among the microscopic-macroscopic-symbolic levels, using crystalline mineral samples and corresponding crystal models. Students explore the relationship between solid-state structure and crystal form. Other structure-property relationships are explored. The…

  15. Crystal Structure of Borophosphate with 61 Screw Axis Helices

    Institute of Scientific and Technical Information of China (English)

    石恒真; 单永奎; 戴立益; 刘煜炎; 翁林红

    2003-01-01

    A brilliant purple octahedral single crystal is hydrothermally synthesized by the reaction of CoCl2·6H2O, H3BO3 and H3PO4 in NaOH aqueous solution of CH3(CH2)15N(CH3)3Br, and its crystal structure has been characterized by single-crystal X-ray diffraction. The compound, NaCo(H2O)2BP2O8·H2O (Mr = 336.72), belongs to hexagonal, space group P6122 with a = 9.447(5), c = 15.83(1) (A。), V = 1223(1) (A。)3, Dc = 2.742 g/cm3, Z = 6, F(000) = 1002 and β= 2.606 mm-1. The three-dimensional framework in the compound is built up from the linkage tetrahedral ribbons, in which the BO4 and PO4 tetrahedra alternate with CoO6 octahedra. The sodium ions and water molecules are located within the free thread of the helical ribbons.

  16. Structural and magnetic studies on copper succinate dihydrate single crystals

    Indian Academy of Sciences (India)

    M P BINITHA; P P PRADYUMNAN

    2017-09-01

    Single crystals of copper succinate dihydrate were grown in silica gel by slow diffusion of copper chloride tosodium metasilicate gel impregnated with succinic acid. The grown crystal was subjected to single crystal X-ray diffractionstudies. In its structure each copper atom is penta co-ordinated to oxygen atoms of four succinate oxygens and oxygenof co-ordinated water molecule. The four bis-bidendate succinate anions form syn–syn bridges among two copper atomsto form a polymeric two-dimensional chain. From room temperature vibrating sample magnetometer (VSM) studies themagnetic moment of the material is calculated as 1.35 Bohr magneton (BM), indicating antiferromagnetic interaction betweencopper atoms and can be explained as due to the orbital overlap of the bridging ligand and the two copper atoms in syn-synorientation. A strong bonding of the magnetic orbital of equatorially oriented Cu atom on both sides of the exchange pathway(Cu–O-C-O–Cu) leads to the anti-ferromagnetic interaction.

  17. Crystal structures of ethylene glycol and ethylene glycol monohydrate.

    Science.gov (United States)

    Fortes, A Dominic; Suard, Emmanuelle

    2011-12-21

    We have carried out a neutron powder diffraction study of deuterated ethylene glycol (1,2-ethanediol), and deuterated ethylene glycol monohydrate with the D2B high-resolution diffractometer at the Institut Laue-Langevin. Using these data, we have refined the complete structure, including all hydrogen atoms, of the anhydrous phase at 220 K. In addition, we have determined the structure of ethylene glycol monohydrate at 210 K using direct space methods. Anhydrous ethylene glycol crystallizes in space-group P2(1)2(1)2(1) with four formula units in a unit-cell of dimensions a = 5.0553(1) Å, b = 6.9627(1) Å, c = 9.2709(2) Å, and V = 326.319(8) Å(3) [ρ(calc)(deuterated) = 1386.26(3) kg m(-3)] at 220 K. Ethylene glycol monohydrate crystallizes in space-group P2(1)/c with four formula units in a unit-cell of dimensions a = 7.6858(3) Å, b = 7.2201(3) Å, c = 7.7356(4) Å, β = 92.868(3)°, and V = 428.73(2) Å(3) [ρ(calc)(deuterated) = 1365.40(7) kg m(-3)] at 210 K. Both the structures are characterized by the gauche conformation of the ethylene glycol molecule; however, the anhydrous phase contains the tGg' rotamer (or its mirror, g'Gt), whereas the monohydrate contains the gGg' rotamer. In the monohydrate, each water molecule is tetrahedrally coordinated, donating two hydrogen bonds to, and accepting two hydrogen bonds from the hydroxyl groups of neighboring ethylene glycol molecules. There are substantial differences in the degree of weak C-D···O hydrogen bonding between the two crystals, which calls into question the role of these interactions in determining the conformation of the ethylene glycol molecule.

  18. Crystal structure of the bacteriophage P2 integrase catalytic domain.

    Science.gov (United States)

    Skaar, Karin; Claesson, Magnus; Odegrip, Richard; Högbom, Martin; Haggård-Ljungquist, Elisabeth; Stenmark, Pål

    2015-11-30

    Bacteriophage P2 is a temperate phage capable of integrating its DNA into the host genome by site-specific recombination upon lysogenization. Integration and excision of the phage genome requires P2 integrase, which performs recognition, cleavage and joining of DNA during these processes. This work presents the high-resolution crystal structure of the catalytic domain of P2 integrase, and analysis of the structure-function relationship of several previously identified non-functional P2 integrase mutants. The DNA binding area is characterized by a large positively charged patch, harboring key residues. The structure reveals potential for large dimer flexibility, likely essential for rearrangement of DNA strands upon integration and excision of the phage DNA.

  19. Crystal structure of Homo sapiens protein LOC79017

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Euiyoung; Bingman, Craig A.; Aceti, David J.; Phillips, Jr., George N. (UW)

    2010-02-08

    LOC79017 (MW 21.0 kDa, residues 1-188) was annotated as a hypothetical protein encoded by Homo sapiens chromosome 7 open reading frame 24. It was selected as a target by the Center for Eukaryotic Structural Genomics (CESG) because it did not share more than 30% sequence identity with any protein for which the three-dimensional structure is known. The biological function of the protein has not been established yet. Parts of LOC79017 were identified as members of uncharacterized Pfam families (residues 1-95 as PB006073 and residues 104-180 as PB031696). BLAST searches revealed homologues of LOC79017 in many eukaryotes, but none of them have been functionally characterized. Here, we report the crystal structure of H. sapiens protein LOC79017 (UniGene code Hs.530024, UniProt code O75223, CESG target number go.35223).

  20. The crystal structure and superconducting properties of monatomic bromine.

    Science.gov (United States)

    Duan, Defang; Meng, Xing; Tian, Fubo; Chen, Changbo; Wang, Liancheng; Ma, Yanming; Cui, Tian; Liu, Bingbing; He, Zhi; Zou, Guangtian

    2010-01-13

    The crystal structure and superconducting properties of monatomic bromine under high pressure have been studied by first-principles calculations. We have found the following phase transition sequence with increasing pressure: from body-centered orthorhombic (bco, phase II) to body-centered tetragonal structure (bct, phase III) at 126 GPa, then to face-centered cubic structure (fcc, phase IV) at 157 GPa, which is stable at least up to 300 GPa. The calculated superconducting critical temperature T(c) = 1.46 K at 100 GPa is consistent with the experimental value of 1.5 K. In addition, our results of T(c) decrease with increasing pressure in all the monatomic phases of bromine, similar to monatomic iodine. Further calculations show that the decrease of λ with pressure in phase IV is mainly attributed to the weakening of the 'soft' vibrational mode caused by pressure.