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Structure Determination (structure + determination)
Kinds of Structure Determination Selected AbstractsSynthesis and Structure Determination of Selenium(IV) CyanidesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008Stefanie Fritz Abstract The reaction of SeF4 with Me3SiCN did not result in thepreparation of the designated Se(CN)4 but Se(CN)F3 and Se(CN)2F2 were obtained as first known selenium(IV)cyanide compounds and characterized by their NMR spectra. Se(CN)2F2 was crystallized as 1,2-dimethoxyethane solvate as well as the corresponding tellurium compound Te(CN)2F2 with very similar structures. NMR spectroscopic data of some more miscellaneous tellurium cyanides and the crystal structures of solvates of Se(CN)2 and oxygen-bridged TeO(CN)2 are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] NMR T1 -Relaxation Measurements on Paramagnetic Organolanthanides:An Alternative Tool for Structure Determination in SolutionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2005Laurent Brachais Abstract 1H NMR investigations were conducted on four paramagnetic organolanthanides, all bearing the tetraisopropylcyclopentadienyl ligand Cp4i (HC5iPr4) in order to verify whether or not interactions observed in the solid state are maintained in solution. In some cases variable-temperature experiments were necessary to enhance the resolution and determine the best conditions for the study. The 1D NMR spectrum could be interpreted in every case. Complementary 2D COSY experiments allowed the full attribution of the signals. T1 (1H) relaxation values were determined for all the paramagnetic complexes at the most suitable temperature, and compared with those of the diamagnetic KCp4i. The same tendency was observed, with particular features concerning the isopropyl groups. Among the four methyl groups, one exhibits a much higher T1 value and one a much lower value; the two others are intermediate. This was interpreted as the result of a privileged conformation of the Cp4i ligand: the two ,-isopropyl groups take up a spatial orientation with one methyl group in the exo position, opposite to the metal atom, whereas the methyl groups of the two ,-isopropyl groups are equidistant from the metal atom. Whatever the nature of the metal (Nd, Sm), the oxidation state (SmII, SmIII) or the temperature (298, 363 K), this conformation is retained. The structure in solution seems to be different from that previously determined in the solid state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Preparation and Structure Determination of a Stable cis -Bis-,-homobenzene Derivative,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2010Dieter Wullbrandt Abstract By cyclopropanation of tetramethyl[2.2]paracyclophane 9 the tetramethylene adduct 10 has been prepared. This hydrocarbon is the first stable cis -bis-,-homobenzene for which a structure has been determined by X-ray diffraction. [source] Isolation and Structure Determination of Aplidinones A,C from the Mediterranean Ascidian Aplidium conicum: A Successful Regiochemistry Assignment by Quantum Mechanical 13C NMR Chemical Shift CalculationsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2005Anna Aiello Abstract A chemical investigation of a Mediterranean ascidian, Aplidium conicum, has resulted in the isolation of the new metabolites aplidinone A (1), B (2), and C (3). The structures of aplidinones A,C were determined by interpretation of spectroscopic data, whereas the regiochemistry was determined by the comparison of experimental 13C NMR chemical shifts with those predicted by GIAO shielding calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Solid-state NMR Structure DeterminationIUBMB LIFE, Issue 9 2003Alison Drechsler Abstract Biological applications of solid-state NMR (SS-NMR) have been predominantly in the area of model membrane systems. Increasingly the focus has been membrane peptides and proteins. SS-NMR is able to provide information about how the peptides or proteins interact with the lipids or other peptides/proteins in the membrane, their effect on the membrane and the location of the peptides or proteins relative to the membrane surface. Recent developments in biological SS-NMR have been made possible by improvements in labelling and NMR techniques. This review discusses aligned systems and magic angle spinning techniques, bilayers and bicelles, and measurement of chemical shift anisotropy and dipolar coupling. A number of specific experiments such as cross polarization, rotational resonance, REDOR, PISEMA, MAOSS and multidimensional experiments are described. In addition to 2H, 13C and 15N, recent solid-sate 1H, 19F and 17O NMR work is discussed. Several examples of the use of SS-NMR to determine the structure of membrane peptides and proteins are given. IUBMB Life, 55: 515-523, 2003 [source] Structure Determination by X-ray Crystallography.JOURNAL OF SYNCHROTRON RADIATION, Issue 3 2006By Mark Ladd, Rex Palmer. First page of article [source] Structure Determination in Colloidal Crystal Photonic Bandgap StructuresJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2002John Ballato Structure/optical property relationships in photonic bandgap structures are evaluated by a novel combination of sample sectioning, microscopy, and image analysis. Disordered colloidal crystals of solution-derived, monosized SiO2 particles were sectioned by focused ion beam (FIB) milling and then imaged using field emission scanning electron microscopy (FE-SEM). Pair correlation and radial distribution functions of the particulate arrangement were generated directly from a binary color scale rendering of the FE-SEM images, therein defining the level of order or disorder in the structure. These experimentally obtained spatial correlation functions were used to compute the scattering spectral properties in an analogous, although inverse (i.e., solving the inverse scattering problem), method to that used in X-ray diffraction for structure determination. Using a first-order approximation to the scattering from a disordered structure, the bandwidth and midgap values for the colloidal crystal photonic bandgap materials were within 15% of those measured. This new methodology promises to provide a simple and direct approach for quantifying the structure/optical property relationships in ordered and disordered photonic crystals directly from standard microstructural imaging techniques. [source] An Efficient Protocol for NMR-Spectroscopy-Based Structure Determination of Protein Complexes in Solution,ANGEWANDTE CHEMIE, Issue 11 2010Bernd Simon Dr. Puzzle-Arbeit: Eine effiziente, allgemein anwendbare Methode zur Bestimmung der Struktur von Proteinkomplexen und Mehrdomänenproteinen in Lösung mithilfe der NMR-Spektroskopie wird vorgestellt. Ausgehend von den bekannten hochaufgelösten Strukturen einzelner Domänen oder Untereinheiten wird die Domänenanordnung des Gesamtsystems aus NMR-Daten abgeleitet, die auch für hochmolekulare Komplexe zugänglich sind. [source] On the Treatment of Conformational Flexibility when Using Residual Dipolar Couplings for Structure Determination,ANGEWANDTE CHEMIE, Issue 36 2009Christina Mission possible! Die Bewegungsmittelung NMR-spektroskopischer Daten erschwert die Bestimmung der Konformation und relativen Konfiguration flexibler organischer Moleküle. Zwei Ansätze zur Behandlung des Konformationsgleichgewichts einer mäßig flexiblen Verbindung (siehe die Überlagerung der beiden Konformere des untersuchten Butyrolactons) mithilfe dipolarer Restkopplungen werden diskutiert. [source] Structure Determination by X-ray Crystallography.ACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2006By Mark Ladd, Rex Palmer. First page of article [source] ChemInform Abstract: Ab initio Structure Determination of Mg10Ir19B16.CHEMINFORM, Issue 42 2009Qiang Xu 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Structure Determination of Gold Clusters by Trapped Ion Electron Diffraction: Au - 14,Au - 19.CHEMINFORM, Issue 33 2009Anne Lechtken 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis, Structure Determination and Calorimetric Study of New Caesium Hydrogen Selenate Arsenate Cs4(SeO4)(HSeO4)2 (H3AsO4).CHEMINFORM, Issue 33 2009M. Amri 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Single-Crystal Structure Determination and Solid-State NMR Investigations of Lithium Nitridosilicate Li2SiN2 Synthesized by a Precursor Approach Employing Amorphous "Si(CN2)2".CHEMINFORM, Issue 28 2009Sandro Pagano 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Crystal Chemistry in the Ag2O,Nb2O5 System , AgNb3O8 Structure Determination.CHEMINFORM, Issue 25 2008Patrick Rozier 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis and Crystal Structure Determination by X-Ray Powder Diffraction of Nickel Tetrametaphosphimate Octahydrate Ni2(PO2NH)4×8H2O.CHEMINFORM, Issue 43 2005S. Rebecca Roemer Abstract For Abstract see ChemInform Abstract in Full Text. [source] Structure Determination of Hydroxytrypargine: A New Tetrahydro-,-carboline Toxin from the Venom of the Spider Parawixia bistriata.CHEMINFORM, Issue 37 2005Lilian M. M. Cesar No abstract is available for this article. [source] Synthesis, Crystal Structure Determination from X-Ray Powder Diffractometry and Vibrational Spectroscopic Properties of Mg[N(CN)2]2×4H2O.CHEMINFORM, Issue 36 2005Elisabeth Irran Abstract For Abstract see ChemInform Abstract in Full Text. [source] High-Pressure Synthesis, Crystal Structure Determination, and a Ca Substitution Study of the Metallic Rhodium Oxide NaRh2O4.CHEMINFORM, Issue 17 2005Kazunari Yamaura Abstract For Abstract see ChemInform Abstract in Full Text. [source] Crystal Growth and Crystal Structure Determination of K2[Pt(CN)4Cl2], K2[Pt(CN)4Br2], K2[Pt(CN)4I2] and K2[Pt(CN)4]Cl2×2H2O.CHEMINFORM, Issue 30 2004Claus Muehle Abstract For Abstract see ChemInform Abstract in Full Text. [source] A New Fluorite Type Compound Pb5Bi17X5O43: Synchrotron and Neutron Structure Determination (X: P) and Conduction Properties (X: P, V and As).CHEMINFORM, Issue 3 2003Pascal Roussel Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of Enantiopure Sulfonimidamides and Elucidation of Their Absolute Configuration by Comparison of Measured and Calculated CD Spectra and X-Ray Crystal Structure DeterminationCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010Christin Worch Abstract Straightforward syntheses of enantiopure N -benzoyl- and N - tert -butyloxycarbonyl-protected sulfonimidamides, which can be used as building blocks in newly designed catalysts, are presented. Key synthetic step is a dynamic resolution of a racemic sulfinic acid sodium salt. All subsequent transformations proceed stereospecifically. The absolute configurations at the sulfur atoms of both sulfonimidamides were determined by comparison of measured and calculated CD spectra. An X-ray crystal structure determination of a sulfonimidoylguanidine derivative confirmed this result. [source] Synthesis, X-ray Single-Crystal Structure Determination, and Magnetic Properties of [Rb(benzo[18]crown-6)]+ Salts Containing Well-Ordered Fulleride Trianions C603,,CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2009Bele Boeddinghaus Dipl.-Chem. Abstract Finally, a structure with well-resolved C603,ions and S=1/2 spin system: The two novel title compounds have clearly S=1/2 and not S=3/2 electronic states, as expected for the occupation of the triply degenerate LUMO of C60. These structures with well-ordered fullerene trianions show that the expected Jahn,Teller distortion is not observable in X-ray diffraction experiments. Crystals of the composition [Rb(benzo[18]crown-6)]3[,3 -C60](C7H8)(C3H7NO)4.5 (1) and [Rb(benzo[18]crown-6)]3[C60](C3H7NO)5.33(C4H8O)1.66 (2) were synthesized by reduction of C60 with elemental rubidium in a mixture of dimethylformamide/tetrahydrofuran in the presence of benzo[18]crown-6. X-ray single-crystal structure determinations reveal well-ordered C60 trianions in both compounds. In contrast to previously reported structures of compounds containing C603, ions the present structure refinements allow the description of the buckyballs with good resolution (R1/wR2 for I>2,(I) (all data) are 0.030/0.069 (0.051/0.071) and 0.042/0.101 (0.076/0.108) for 1 and 2, respectively). In 1 the C603, unit coordinates in an ,3 -fashion to one Rb atom, whose coordination sphere is completed by one benzo[18]crown-6 and one dimethylformamide molecule. In 2 no coordination of the alkali metal atom to the C60 trianion is observed. Magnetic measurements for 1 reveal a magnetic moment of 1.74,,B, as expected for an isolated S=1/2 spin system. The high-quality data of the present studies allowed a comparison of structural details of C603, ions with other C60n, units (n=0, 2, 3) and a discussion of the structural Jahn,Teller distortions. [source] The Stuffed Framework Structure of SrP2N4: Challenges to Synthesis and Crystal Structure DeterminationCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2007Friedrich Abstract SrP2N4 was obtained by high-pressure high-temperature synthesis utilizing the multianvil technique (5,GPa, 1400,°C) starting from mixtures of phosphorus(V) nitride and strontium azide. SrP2N4 turned out to be isotypic with BaGa2O4 and is closely related to KGeAlO4. The crystal structure (SrP2N4, a=17.1029(8), c=8.10318(5),Å, space group P63 (no. 173), V=2052.70(2),Å3, Z=24, R(F2)=0.0633) was solved from synchrotron powder diffraction data by applying a combination of direct methods, Patterson syntheses, and difference Fourier maps adding the unit cell information derived from electron diffraction and symmetry information obtained from 31P solid-state NMR spectroscopy. The structure of SrP2N4 was refined by the Rietveld method by utilizing both neutron and synchrotron X-ray powder diffraction data, and has been corroborated additionally by 31P solid-state NMR spectroscopy by employing through-bond connectivities and distance relations. [source] Strategies and Tools for Structure Determination of Natural Products Using Modern Methods of NMR SpectroscopyCHEMISTRY & BIODIVERSITY, Issue 2 2005Nadja Bross-Walch First page of article [source] Structure Determination of an Organometallic 1-(Diazenylaryl)ethanol: A Novel Toxin Subclass from the Web of the Spider Nephila clavipesCHEMISTRY & BIODIVERSITY, Issue 6 2004Maurício, Ribeiro Marques A novel chemical subclass of toxin, [1-(3-diazenylphenyl)ethanol]iron, was identified among the compounds present in the web of the spider Nephila clavipes. This type of compound is not common among natural products, mainly in spider-venom toxins; it was shown to be a potent paralytic and/or lethal toxin applied by the spider over its web to ensure prey capture only by topical application. The structure was elucidated by means of ESI mass spectrometry, 1H-NMR spectroscopy, high-resolution (HR) mass spectrometry, and ICP spectrometry. The structure of [1-(3-diazenylphenyl)ethanol]iron and the study of its insecticidal action may be used as a starting point for the development of new drugs for pest control in agriculture. [source] Structure Determination of Resorcinol Rotamers by High-Resolution UV SpectroscopyCHEMPHYSCHEM, Issue 10 2005Grzegorz Myszkiewicz Abstract The rotationally resolved S1,S0 electronic origins of several deuterated resorcinol rotamers cooled in a molecular beam have been recorded. An automated assignment of the observed spectra has been performed using a genetic algorithm approach with an asymmetric rotor Hamiltonian. The structures of resorcinol A and resorcinol B were derived from the rotational constants of twenty deuterated species for both electronic states. The lifetimes of different resorcinol isotopomers in the S1 state are also reported. As is the case for phenol, these lifetimes mainly depend on the position of deuteration. A nearly perfect additivity of the zero-point energies after successive deuterations in resorcinol rotamers has been discovered and subsequently used in the full assignment of the previously reported low-resolution spectra of deuterated resorcinol A. An analogous spectrum is also predicted for the resorcinol B rotamer. [source] Syntheses, Crystal Structures and Magnetic Properties of Carboxylato-Bridged Polymeric Networks of MnIIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006Subal Chandra Manna Abstract Three new carboxylato-bridged polymeric networks of MnII having,molecular formula [Mn(ox)(dpyo)]n (1), {[Mn2(mal)2(bpee)(H2O)2]·0.5(bpee)·0.5(CH3OH)}n (2) and {[Mn3(btc)2(2,2,-bipy)2(H2O)6]·4H2O}n (3) [dpyo, 4,4,-bipyridine N,N,-dioxide; bpee, trans -1,2 bis(4-pyridyl)ethylene; 2,2,-bipy, 2,2,-bipyridine; ox = oxalate dianion; mal = malonate dianion; btc = 1,3,5-benzenetricarboxylate trianion] have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature magnetic measurements. Structure determination of complex 1 reveals a covalent bonded 2D network containing bischelating oxalate and bridging dpyo; complex 2 is a covalent bonded 3D polymeric architecture, formed by bridging malonate and bpee ligands, resulting in an open framework with channels filled by uncoordinated disordered bpee and methanol molecules. Whereas complex 3, comprising btc anions bound to three metal centers, is a 1D chain which further extends its dimensionality to 3D via - and H-bonding interactions. Low temperature magnetic measurements reveal the existence of weak antiferromagnetic interaction in all these complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Structure determination of diclofenac in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction dataJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2004Nongnuj Muangsin The structure determination of diclofenac embedded in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data is demonstrated. It reveals that sodium diclofenac, the starting material in the preparation of a controlled-release diclofenac-containing chitosan matrix, changes to diclofenac acid in space group C2/c in the matrix. Simple methods were employed for handling the sample to obtain X-ray powder diffraction data of sufficiently high quality for the determination of the crystal structure of diclofenac embedded in chitosan. These involved grinding and sieving several times through a micro-mesh sieve to obtain a suitable particle size and a uniformly spherical particle shape. A traditional technique for structure solution from X-ray powder diffraction data was applied. The X-ray diffraction intensities were extracted using Le Bail's method. The structure was solved by direct methods from the extracted powder data and refined using the Rietveld method. For comparison, the single-crystal structure of the same drug was also determined. The result shows that the crystal structure solved from conventional X-ray powder diffraction data is in good agreement with that of the single crystal. The deviations of the differences in bond lengths and angles are of the order of 0.030,Å and 0.639°, respectively. [source] Structure determination of N -methyl-tetrahydro-5H -indazol-5-onesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2006Kurt A. Josef This paper communicates the (regio) synthesis and a convenient NMR structural assignment method for N -methyl-tetrahydro-5H -indazol-5-one isomers. The cyclization reaction of 7-(hydroxymethylene)-1,4-dioxaspiro[4,5]decan-8-one (3) with methylhydrazine yields, after de-protection predominately the N-2 methyl isomer 2. Analysis of the product ratio and structural assignments are based on NMR data including NOE difference experiments and subsequently confirmed with X-ray crystallography. These findings are in sharp contrast with the literature. The experimental conditions used to optimize the synthesis of the individual isomers are discussed. [source] | |||||||||||||||||||||||||||||||