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Crystalline State (crystalline + state)
Selected AbstractsGa24Br18Se2: A Highly Symmetrical Metalloid Cluster and Its One-Dimensional Arrangement in the Crystalline State as a Model for the Photoconductivity of Solid GaSe.CHEMINFORM, Issue 44 2007Jens Hartig Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] ChemInform Abstract: An Unexpected Paterno,Buechi Reaction in the Crystalline State.CHEMINFORM, Issue 11 2002Ting Kang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Crystal structure of a polar nematogen 4-(trans- 4-undecylcyclohexyl) isothiocyanatobenzeneCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2007S. Biswas Abstract Crystal and molecular structures of a nematogenic compound 4-(trans- 4-undecylcyclohexyl) isothiocyanatobenzene (11CHBT) have been determined by direct methods using single crystal X-ray diffraction data. The compound (C24H37N1S1) crystallizes in the monoclinic system with the space group P21/c and Z = 4. The unit cell parameters are a = 5.5539(11) Å, b = 8.1341(10) Å, c = 51.494(5) Å, and (= 91.127(14)0. The structure was refined to Rw = 0.051. The molecule is found to be slightly bow-shaped though the alkyl chain is in all- trans conformation. The phenyl ring and the alkyl chain are planar and the cyclohexyl group is in chair conformation. The isothiocyanato groups are almost linear. Parallel imbricated mode of packing of the molecules is found in the crystalline state which is precursor to the nematic phase structure. There are many van der Waals' interactions particularly in the isothiocyanato benzene part of the molecule. Of the various associated pairs of molecules the one having anti-parallel configuration with overlaps in the isothiocyanato phenyl group probably exists in both the crystalline and the nematic phases. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Raman spectroscopic and X-ray investigation of stressed states in diamond-like carbon filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1-2 2005R. Krawietz Abstract The non-destructive characterization of intrinsic stress is very important to evaluate the reliability of devices based on diamond-like carbon (DLC) films. Whereas the only requirement for the X-ray diffraction method is a crystalline state of specimen, Raman spectroscopic stress analysis is restricted to materials showing intensive and sharp Raman peaks. On the other hand, Raman spectroscopy offers the possibility to measure stress profiles with lateral resolution of about 1 micron. The results of stress measurements in DLC films using both X-ray diffraction and Raman spectroscopy are found in very good correspondence. Mean stress in carbon films consisting of very small crystallites on silicon substrates has been determined by measuring and fitting the stress profiles in the substrate near artificial vertical film edges. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Complexes of Yb3+ with EDTA and CDTA , Molecular and Electronic StructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2008Janicki Abstract Two Yb3+ compounds, [C(NH2)3]2[Yb(EDTA)(H2O)2]ClO4·6H2O and [C(NH2)3][Yb(CDTA)(H2O)2]·4H2O, where EDTA is the ethylenediaminetetraacetate anion and CDTA is the trans -1,2-diaminecyclohexane- N,N,N,,N, -tetraacetate anion, were obtained and their crystal structures and spectroscopic properties were determined. In both compounds, the coordination geometries of the eight-coordinate Yb3+ ion are very similar. In each case, the inner sphere of the metal ion consists of four carboxyl oxygen atoms, two nitrogen atoms and two water molecules. The complexes were characterized by UV/Vis/NIR absorption at different temperatures and IR spectroscopy. The spectroscopic results revealed high sensitivity of the electronic 4f13 configuration upon minor changes in the coordination geometry around the Yb3+ ion. These data also demonstrate that species present in solutions of Yb3+,EDTA are similar to those found in the crystal, whereas in solutions of Yb3+,CDTA an equilibrium between at least two different forms exists. For the Yb3+,EDTA complex in solution and in the crystalline state, a charge-transfer transition was detected. Theoretical calculations revealed its complicated (Yb , ligand and ligand , Yb) character.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Monophosphanylcalix[6]arene Ligands: Synthesis Characterization, Complexation, and Their Use in CatalysisEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2006Yasushi Obora Abstract Novel phosphanylcalix[6]arenes having mono- O -diphenylphosphanylmethyl (3) and mono- O -(4-diphenylphosphanylphenyl)methyl substituents (5) have been synthesized. The structures of these monophosphanylcalix[6]arenes were determined by NMR spectroscopy, mass spectrometry, and X-ray crystal structure analysis. The X-ray structure reveals that 3 adopts a flattened 1,2,3-alternate conformation in the crystalline state, while the NMR spectra show that 3 and 5 have a cone conformation in solution. Structure optimization and energy calculations for 3 and 5 at the B3LYP/LANL2DZ-CONFLEX5/MMFF94s level of theory show that the cone conformation is slightly more stable than the 1,2,3-alternate conformation by 0.36 kcal,mol,1 for 3 and 0.96 kcal,mol,1 for 5. Complexation of 3 with [PtCl2(COD)] and [Rh(COD)2]BF4 gives cis -coordinated [PtCl2(3)2] and [Rh(COD)(3)2]BF4, respectively. The X-ray analysis of [PtCl2(3)2] shows that 3 adopts a cone conformation upon complexation. Combination of 3 and 5 with [Rh(COD)2]BF4 provides an active catalyst for the hydroformylation of a variety of terminal alkenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Towards Understanding of the Selective Precipitation of Alkali Metal Cations in Presence of Dipicrylamine AnionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Suresh Eringathodi Abstract Dipicrylamine anion (DPA,) precipitates out [K(DPA)] with high selectivity from salt bitterns containing Na+, K+, and Mg2+, whereas the same ligand shows poor selectivity towards K+ , and much higher selectivity towards Cs+ , in studies conducted with a mixture of K+, Rb+, and Cs+. Their single-crystal structures reveal that the K+ and Rb+ salts have similar layered structures, with 8 oxygen atoms from seven DPA, anions encapsulating the metal cation, whereas the Cs+ salt possesses a channel-like structure with the metal ion encapsulated by ten oxygen atoms from six DPA,. The conformation of DPA, in the [Cs(DPA)] single crystal matches closely that of DPA in crystalline state. M···O and intermolecular C,H···O interactions together stabilize the structures. The 133Cs NMR spectrum of the poorly soluble [Cs(DPA)] shows an upfield shift of the peak with respect to CsCl as a result of the interaction with the oxygen atoms of DPA,, whereas 23Na NMR spectrum of the highly soluble [Na(DPA)] shows no such upfield shift compared to NaCl. Powder XRD patterns of bulk [M(DPA)] (M = K+, Rb+, and Cs+) precipitates show that these are similar to the patterns obtained by simulation of the single-crystal X-ray data. The selectivity of precipitation correlates qualitatively with the size and hydration enthalpies of the ions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Three-dimensional structure of the histidine-containing phosphocarrier protein (HPr) from Enterococcus faecalis in solutionFEBS JOURNAL, Issue 3 2001Till Maurer The histidine-containing phosphocarrier protein (HPr) transfers a phosphate group between components of the prokaryotic phosphoenolpyruvate-dependent phosphotransferase system (PTS), which is finally used to phosphorylate the carbohydrate transported by the PTS through the cell membrane. Recently it has also been found to act as an intermediate in the signaling cascade that regulates transcription of genes related to the carbohydrate-response system. Both functions involve phosphorylation/dephosphorylation reactions, but at different sites. Using multidimensional 1H-NMR spectroscopy and angular space simulated annealing calculations, we determined the structure of HPr from Enterococcus faecalis in aqueous solution using 1469 distance and 44 angle constraints derived from homonuclear NMR data. It has a similar overall fold to that found in HPrs from other organisms. Four , strands, A, B, C, D, encompassing residues 2,7, 32,37, 40,42 and 60,66, form an antiparallel , sheet lying opposite the two antiparallel , helices, a and c (residues 16,26 and 70,83). A short , helix, b, from residues 47,53 is also observed. The pairwise root mean square displacement for the backbone heavy atoms of the mean of the 16 NMR structures to the crystal structure is 0.164 nm. In contrast with the crystalline state, in which a torsion angle strain in the active-center loop has been described [Jia, Z., Vandonselaar, M., Quail, J.W. & Delbaere, L.T.J. (1993) Nature (London) 361, 94,97], in the solution structure, the active-site His15 rests on top of helix a, and the phosphorylation site N,1 of the histidine ring is oriented towards the surface, making it easily accessible to the solvent. Back calculation of the 2D NOESY NMR spectra from both the NMR and X-ray structures shows that the active-center structure derived by X-ray crystallography is not compatible with experimental data recorded in solution. The observed torsional strain must either be a crystallization artefact or represents a conformational state that exists only to a small extent in solution. [source] Solid-state conformation of the 1,3,2-oxazaphospholane ring in 2-dialkylamino-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholane sulfidesHETEROATOM CHEMISTRY, Issue 3 2001Rafal Kruszynski Dialkylamino-3,4-dimethyl-5-phenyl-1,3,2-oxazaphospholane sulfides (where the alkyl is an isopropyl, ethyl or methyl group) was obtained by sulfurization of the respective phospholanes. The structures of these compounds were determined by X-ray crystal structure analysis. Five-membered rings exist in the envelope conformation in the crystalline state. The planar part of the 1,3,2-oxazaphospholane rings undergoes twisting with the enlargement of a substituent. The environment of the P atom has the geometry of a distorted tetrahedron. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:146,150, 2001 [source] Effect of Molecular Morphology on Amplified Spontaneous Emission of Bis-Styrylbenzene DerivativesADVANCED MATERIALS, Issue 40 2009Ryota Kabe Molecular aggregation greatly affects the fluorescence quantum efficiency, transient lifetime, and amplified spontaneous emission (ASE) of bis-styrylbenzene derivatives. We compare the optical properties for various morphologies (solution, film, doped film, and single crystalline state) (see figure) and demonstrate that ambipolar operation of a 1,4-bis(4-methylstyryl) benzene layer in field-effect transistors leads to intense blue electroluminescence with a rather sharp emission width. [source] The Dependence of Crystal Structure of Te-Based Phase-Change Materials on the Number of Valence Electrons,ADVANCED MATERIALS, Issue 5 2004M. Luo A simple criterion to identify potential phase-change materials is developed using density functional theory. These compounds rely on the switching between an amorphous and a crystalline state. Here it is demonstrated that suitable alloys have an average valence electron number larger than 4.1 and show p-electron bonding leading to a six-fold coordination, while materials with a smaller number of valence electrons favor sp3 -bonding (see Figure). [source] Wave functions derived from experiment.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2003Abstract The constrained Hartree,Fock method using experimental X-ray diffraction data is extended and applied to the case of noncentrosymmetric molecular crystals. A new way to estimate the errors in derived properties as a derivative with respect to added Gaussian noise is also described. Three molecular crystals are examined: ammonia [NH3], urea [CO(NH2)2], and alloxan [(CO)4(NH)2]. The energetic and electrical properties of these molecules in the crystalline state are presented. In all cases, an enhancement of the dipole moment is observed upon application of the experimental constraint. It is found that the phases of the structure factors are robustly determined by the constrained Hartree,Fock model, even in the presence of simulated noise. Plots of the electron density, electrostatic potential, and the electron localization function for the molecules in the crystal are displayed. In general, relative to the Hartree,Fock model, there is a depletion of charge around hydrogen atoms and lone pair regions, and a build-up of charge within the molecular framework near nuclei, directed along the bonds. The electron localization function plots reveal an increase in the pair density between vicinal hydrogen atoms. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 470,483, 2003 [source] Quantitation of crystalline and amorphous forms of anhydrous neotame using 13C CPMAS NMR spectroscopyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2005Thomas J. Offerdahl Abstract Although most drugs are formulated in the crystalline state, amorphous or other crystalline forms are often generated during the formulation process. The presence of other forms can dramatically affect the physical and chemical stability of the drug. The identification and quantitation of different forms of a drug is a significant analytical challenge, especially in a formulated product. The ability of solid-state 13C NMR spectroscopy with cross polarization (CP) and magic-angle spinning (MAS) to quantify the amounts of three of the multiple crystalline and amorphous forms of the artificial sweetener neotame is described. It was possible to quantify, in a mixture of two anhydrous polymorphic forms of neotame, the amount of each polymorph within 1,2%. In mixtures of amorphous and crystalline forms of neotame, the amorphous content could be determined within 5%. It was found that the crystalline standards that were used to prepare the mixtures were not pure crystalline forms, but rather a mixture of crystalline and amorphous forms. The effect of amorphous content in the crystalline standards on the overall quantitation of the two crystalline polymorphic forms is discussed. The importance of differences in relaxation parameters and CP efficiencies on quantifying mixtures of different forms using solid-state NMR spectroscopy is also addressed. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:2591,2605, 2005 [source] Improvement of dissolution and oral absorption of ER-34122, a poorly water-soluble dual 5-lipoxygenase/cyclooxygenase inhibitor with anti-inflammatory activity by preparing solid dispersionJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Ikuo Kushida Abstract Several formulation approaches were attempted to improve the dissolution and the oral absorption of ER-34122, which is a novel dual 5-lipoxygenase/cyclooxygenase inhibitor with potent anti-inflammatory activity. The solid dispersion of ER-34122 with hydroxypropylmethylcellulose (TC-5RW), which is an inert solid carrier, resulted in a significant improvement in the dissolution rate of ER-34122. The solid dispersion was prepared by a solvent evaporation method using ethanol and water. The solid-state characteristics of the solid dispersion, the corresponding physical mixture, and ER-34122 alone were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy (FTIR), and an automated controlled-atmosphere microbalance. The X-ray powder diffraction patterns suggest that the solid dispersion exists in a totally amorphous state and the others exist in a crystalline state. The FTIR spectra results suggest that ER-34122 can interact with TC-5RW through intermolecular hydrogen bonding in the solid dispersion. This interaction may cause a stabilization of ER-34122 in the higher-energy, faster-dissolving amorphous state. The dissolution rate of ER-34122 from the solid dispersion was significantly greater than that from the physical mixture or the pure drug. Furthermore, when orally administrated to beagle dogs, ER-34122 showed about a 100-fold increase in both maximum concentration (Cmax) and area under the curve of concentration versus time (AUC) compared with the pure drug. Consequently, it was determined that the solid dispersion technique with TC-5RW provides a promising way to increase the dissolution rate and the oral absorption of poorly water-soluble drugs such as ER-34122. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:258,266, 2002 [source] Enhanced solubility and dissolution rate of lamotrigine by inclusion complexation and solid dispersion techniqueJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2008Vikram R. Shinde ABSTRACT The solid-state properties and dissolution behaviour of lamotrigine in its inclusion complex with ,-cyclodextrin (,CD) and solid dispersions with polyvinylpyrrolidone K30 (PVP K30) and polyethyl-eneglycol 6000 were investigated. The phase solubility profile of lamotrigine with ,CD was classified as AL -type, indicating formation of a 1:1 stoichiometry inclusion complex, with a stability constant of 369.96 ± 2.26 M,1. Solvent evaporation and kneading methods were used to prepare solid dispersions and inclusion complexes, respectively. The interaction of lamotrigine with these hydrophilic carriers was evaluated by powder X-ray diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry. These studies revealed that the drug was no longer present in crystalline state but was converted to an amorphous form. Among the binary systems tested, PVP K30 (1:5) showed greatest enhancement of the solubility and dissolution of lamotrigine. [source] Synthesis and characterization of new alternating, amphiphilic, comblike copolymers of poly(ethylene oxide) macromonomer and N -phenylmaleimideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2005Luminita Cianga Abstract A surface-active p -vinyl benzyloxy-,-hydroxy-poly(ethylene oxide) macromonomer containing 22 pendant structural units of ethylene oxide (St,PEO22) was synthesized with an initiation method. Because of its solubility in a large variety of solvents, the free-radical copolymerization with electron-acceptor N -phenylmaleimide (NPMI) was performed at 60 °C in benzene and tetrahydrofuran (THF) as isotropic media and in a water,THF mixture or water as a heterogeneous medium. Oil-soluble 2,2,-azobisisobutyronitrile and water-soluble 4,4,-azobis(4-cyanovaleric acid) were used as the initiators at fixed concentrations. Two different St,PEO22/NPMI comonomer ratios (1/1 and 3/7) at a fixed total comonomer concentration in the polymerization system were used. The structures, compositions, and microstructure peculiarities of the obtained alternating, amphiphilic, comblike copolymers were determined by NMR analysis. For the copolymers synthesized in hydrophilic media, differential scanning calorimetry showed, near the endothermic peak attributed to the melting of the poly(ethylene oxide) side chains, the presence of a second peak due to the partially ordered phase that could exist between the crystalline state and the isotropic melt. Also, the thermal stability of the obtained copolymers was studied with thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 479,492, 2005 [source] X-ray induced reduction of the crystal of high-molecular-weight cytochrome c revealed by microspectrophotometryJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2004Midori Sato The crystal structures of high-molecular-weight cytochrome c (HMC) from Desulfovibrio vulgaris Hildenborough in the transient and reduced states have been determined at 2.8 Å resolution. An absorption spectrum measured with microspectrophotometor indicated that about 86% of the hemes were reduced after 45 min irradiation of the X-ray beam. Further exposure for 90 min did not significantly change the spectrum. These results suggest that HMC in the crystalline state is easily reduced by illumination of the X-ray beam from synchrotron radiation. [source] X-ray analyses of d(GCGAXAGC) containing G and T at X: the base-intercalated duplex is still stable even in point mutants at the fifth residueJOURNAL OF SYNCHROTRON RADIATION, Issue 1 2004Jiro Kondo DNA fragments containing the sequence d(GCGAAAGC) prefer to adopt a base-intercalated (zipper-like) duplex in the crystalline state. To investigate effects of point mutation at the 5th residue on the structure, two crystal structures of d(GCGAGAGC) and d(GCGATAGC) have been determined by X-ray crystallography. In the respective crystals, the two octamers related by a crystallographic two-fold symmetry are aligned in an anti-parallel fashion and associated to each other to form a duplex, suggesting that the base-intercalated duplex is stable even when the 5th residue is mutated with other bases. The sheared G3:A6 pair formation makes the two phosphate backbones closer and facilitates formation of the A-X*-X-A* base-intercalated motif. The three duplexes are assembled around the three-fold axis, and their 3rd and 4th residues are bound to the hexamine cobalt chloride. The central 5th residues are bound to another cation. [source] Titanium-Catalyzed Norbornene Oligomerization.MACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 20063- exo -Disyndiotactic Structure, Isolation of a Crystalline Heptamer with a Abstract Summary: Norbornene (NB) was oligomerized at 0,°C using AlEt2Cl-TiCl4 at a monomer/titanium molar ratio of about 11. The oligomerization product consists of a fraction soluble in diethyl ether, amorphous by X-ray examination, and of a crystalline fraction, insoluble in diethyl ether. The crystalline fraction was shown by powder X-ray diffraction to consist of a NB heptamer. Single-crystal X-ray analysis indicated that the heptamer had a stereoregular 2,3- exo -disyndiotactic structure. The heptamer adopts a strained, highly irregular, folded conformation in the crystalline state. Structural differences with respect to NB oligomers obtained with zirconocene catalysts are discussed. A view of the molecular structure of the crystalline NB heptamer. [source] Conformational states of human H-Ras detected by high-field EPR, ENDOR, and 31P NMR spectroscopy ,MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2005Michael Spoerner Abstract Ras is a central constituent of the intracellular signal transduction that switches between its inactive state with GDP bound and its active state with GTP bound. A number of different X-ray structures are available. Different magnetic resonance techniques were used to characterise the conformational states of the protein and are summarised here. 31P NMR spectroscopy was used as probe for the environment of the phosphate groups of the bound nucleotide. It shows that in liquid solution additional conformational states in the GDP as well as in the GTP forms coexist which are not detected by X-ray crystallography. Some of them can also be detected by solid-state NMR in the micro crystalline state. EPR and ENDOR spectroscopy were used to probe the environment of the divalent metal ion (Mg2+ was replaced by Mn2+) bound to the nucleotide in the protein. Here again different states could be observed. Substitution of normal water by 17O-enriched water allowed the determination of the number of water molecules in the first coordination sphere of the metal ion. In liquid solution, they indicate again the existence of different conformational states. At low temperatures in the frozen state ENDOR spectroscopy suggests that only one state exists for the GDP- and GTP-bound form of Ras, respectively. Copyright © 2005 John Wiley & Sons, Ltd. [source] Dependence of magnetoimpedance effect on nanocrystalline structure of Fe-based amorphous ribbonsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004I. Z. Rahman Abstract This study investigates the magnetoimpedance (MI) behaviour and its dependence on the nanocrystalline structure due to annealing of nominal composition Fe73.5Cu1Nb3Si13.5B9 metallic glass ribbons. Differential Thermal Analyses have shown two distinct stages of primary and secondary crystallisations at ,532 °C and ,703 °C, respectively. XRD, SEM and AFM have shown the evidence of nanocrystallization and surface roughness initiated by changes from glassy to primary crystalline state. Coercivity has decreased near the primary crystallisation temperature and a monotonous increase between the two stages of crystallisation. Beyond the secondary crystallization temperature, the coercivity value remained practically unchanged. Magnetoimpedance ratio (MIR) is found to be sensitive to the annealing temperature. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and Characterization of a New Class of Energetic Compounds , Ammonium NitriminotetrazolatesPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2008Thomas Abstract 1-Methyl-5-nitriminotetrazole (1) and 2-methyl-5-nitraminotetrazole (2) obtained by nitration of 1-methyl-5-aminotetrazole (3) and 2-methyl-5-aminotetrazole (4) were deprotonated using aqueous ammonia solution yielding the energetic compounds, ammonium 1-methyl-5-nitriminotetrazolate (5) and ammonium 2-methyl-5-nitriminotetrazolate (6). The nitrogen-rich salts were tested and characterized comprehensively using vibrational spectroscopy (Infrared (IR) and Raman), multinuclear (1H, 13C, 14N, and 15N) NMR spectroscopy, and elemental analysis. The molecular structures in the crystalline state were determined using low temperature single crystal X-ray diffraction. The thermal behavior and the decompositions were investigated using differential scanning calorimetry (DSC) and gas IR spectroscopy. The heats of formation were calculated using bomb calorimetric measurements. In addition, the relevant detonation parameters, like the detonation pressure and velocity of detonation were calculated using the software EXPLO5 outperforming the values of TNT. Last but not least the sensitivities were determined using BAM methods showing moderate values against impact and friction (drophammer and friction tester) and the long-term stabilities were tested using Flexy Thermal safety calorimetry (TSC). X-ray crystallography: 5: monoclinic, P21/c, a=370.06(2),pm, b=2079.06(9),pm, c=859.69(5),pm, ,=99.120(5)°, V=65306(6),pm3, Z=4, ,calc=1.639,g cm,3; 6: monoclinic, P21, a=365.39(2),pm, b=,788.82(5),pm, c=1124.95(7),pm, ,=91.818(6), V=32408(3),pm3, Z=2, ,calc=1.651,g cm,3. [source] Mistic: Cellular localization, solution behavior, polymerization, and fibril formation,PROTEIN SCIENCE, Issue 7 2009Hay Dvir Abstract Mistic represents a family of unique membrane-associating proteins originally found in Bacillus subtilis (M110). As a fusion partner, it has been shown to assist overexpression of foreign integral membrane proteins in E. coli. We have expressed shorter Mistic homologs from other Bacillus species and surprisingly, unlike M110, found them abundant in the cytoplasm. These Mistic homologs including the corresponding shorter sequence (amino acids 27 through 110 of M110) exist as multimeric assemblies in solution in the absence of detergent. Crystals of Mistic from B. leicheniformis (M2) diffracted to 3.2 Å resolution, indicating that it exists as a multimer in the crystalline state as well. Moreover, we show that although M2 is mostly ,-helical, it tends to polymerize and form fibrils. Such oligomerization could potentially mask the charged surface of the monomeric Mistic to assist membrane integration. [source] Simultaneous fitting of X-ray and neutron diffuse scattering dataACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2007D. J. Goossens Conventional crystallographic refinement uses the Bragg-peak intensities and gives the single-site average crystal structure. Information about short-range order and local order is contained in the diffuse scattering that is distributed throughout reciprocal space. Models of the short-range order in materials can now be automatically refined. The complementarity of X-ray and neutron diffraction data, and the value of simultaneously refining a structural model against both types of data, has long been known. This paper presents the first refinement of a short-range-order model against comprehensive X-ray and neutron diffuse scattering data simultaneously. The sample is the organic molecular crystal benzil, C14H10O2 (for neutron work H is replaced by D). The technique gives new insights into local order in crystalline materials, including the dynamic correlation structure indicative of the dynamics of molecules in the crystalline state, and successfully overcomes limitations of using only the X-ray data set. [source] Structure of Ce2RhIn8: an example of complementary use of high-resolution neutron powder diffraction and reciprocal-space mapping to study complex materialsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2006J. L. Sarrao The room-temperature crystal structure of the heavy fermion antiferromagnet Ce2RhIn8, dicerium rhodium octaindide, has been studied by a combination of high-resolution synchrotron X-ray reciprocal-space mapping of single crystals and high-resolution time-of-flight neutron powder diffraction. The structure is disordered, exhibiting a complex interplay of non-periodic, partially correlated planar defects, coexistence and segregation of polytypic phases (induced by periodic planar `defects'), mosaicity (i.e. domain misalignment) and non-uniform strain. These effects evolve as a function of temperature in a complicated way, but they remain down to low temperatures. The room-temperature diffraction data are best represented by a complex mixture of two polytypic phases, which are affected by non-periodic, partially correlated planar defects, differ slightly in their tetragonal structures, and exhibit different mosaicities and strain values. Therefore, Ce2RhIn8 approaches the paracrystalline state, rather than the classic crystalline state and thus several of the concepts of conventional single-crystal crystallography are inapplicable. The structural results are discussed in the context of the role of disorder in the heavy-fermion state and in the interplay between superconductivity and magnetism. [source] A novel chelatofore functionalized spiropyran of the 2-oxaindane seriesACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Antony O. Bulanov A novel chelatofore functionalized spiropyran of the 2-oxaindane series, namely 8-formyl-7-hydroxy-3,,3,-dimethylspiro[2H -chromene-2,1,(3,H)-2-benzofuran], C19H16O4, is reported. In the crystalline state, dimers are formed as a result of the ,,, stacking of aromatic groups of the 2H -chromene part of the molecule and C,H...O interactions. The Cspiro,O bond length in the pyran ring is 1.4558,(10),Å, which is longer than or equal to the bond length in thermo- and photochromic 2-oxaindane spiropyrans synthesized previously, except for the 7,8-benzo/6-NO2 derivative, in which this bond length is 1.465,(2),Å. [source] 2,-Deoxy-5-propynyluridine: a nucleoside with two conformations in the asymmetric unitACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Simone Budow The title compound, 1-(2-deoxy-,- d - erythro -pentofuranosyl)-5-(prop-1-ynyl)pyrimidin-2,4(1H,3H)-dione, C12H14N2O5, shows two conformations in the crystalline state: conformer 1 adopts a C2,- endo (close to 2E; S -type) sugar pucker and an anti nucleobase orientation [, = ,134.04,(19)°], while conformer 2 shows an S sugar pucker (twisted C2,- endo,C3,- exo), which is accompanied by a different anti base orientation [, = ,162.79,(17)°]. Both molecules show a +sc (gauche, gauche) conformation at the exocyclic C4,,C5, bond and a coplanar orientation of the propynyl group with respect to the pyrimidine ring. The extended structure is a three-dimensional hydrogen-bond network involving intermolecular N,H...O and O,H...O hydrogen bonds. Only O atoms function as H-atom acceptor sites. [source] The surprising sp rotameric structure of 9-methyl-9-pivaloylfluoreneACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2000Cal Y. Meyers Methylation of 9-lithiated ap -9-pivaloylfluorene, (I), as well as pivaloylation of 9-lithiated 9-methylfluorene provided rotationally stable sp -9-methyl-9-pivaloylfluorene, (III), C19H20O, which lies about a crystallographic mirror plane. Fluorene (I) exists exclusively in the ap configuration in solution (NMR) as well as in the crystalline state, reflecting the unfavorable interaction between the tert -butyl and fluorene-ring , electrons in the sp configuration. The existence of (III) exclusively in the sp configuration indicates that, in this case, the interaction between the tert -butyl group and the fluorene-ring , electrons provides relatively more thermodynamic stability than the steric interaction between the tert -butyl and 9-methyl groups (ap configuration). [source] 2-(1,3-Dithian-2-yl)benzaldehyde and N -{2-[2-(1,3-dioxan-2-yl)phenoxy]ethyl}phthalimideACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2000Paul G. Jene The crystal structures of two elaborated-porphyrin precursors have been determined. In the crystalline state, 2-(1,3-dithian-2-yl)benzaldehyde, C11H12OS2, has its dithiane ring in a slightly distorted chair conformation. The molecules pack in anti-parallel chains. N -{2-[2-(1,3-Dioxan-2-yl)phenoxy]ethyl}phthalimide, C20H19NO5, is in a folded conformation. The dihedral angle between the phthalimide and phenyl planes is 80.07,(3)°. In the crystalline states, molecules stack on top of one another. [source] Temperature-dependent macromolecular X-ray crystallographyACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010Martin Weik X-ray crystallography provides structural details of biological macromolecules. Whereas routine data are collected close to 100,K in order to mitigate radiation damage, more exotic temperature-controlled experiments in a broader temperature range from 15,K to room temperature can provide both dynamical and structural insights. Here, the dynamical behaviour of crystalline macromolecules and their surrounding solvent as a function of cryo-temperature is reviewed. Experimental strategies of kinetic crystallography are discussed that have allowed the generation and trapping of macromolecular intermediate states by combining reaction initiation in the crystalline state with appropriate temperature profiles. A particular focus is on recruiting X-ray-induced changes for reaction initiation, thus unveiling useful aspects of radiation damage, which otherwise has to be minimized in macromolecular crystallography. [source] | |||||||||||||||||||||||||||||||