Crystal-structure and Mössbauer studies of Li1.746Nd4.494FeO9.493

The Li_1.746Nd_4.494FeO_9.493 (LNF) ternary phase, located in the Li₂O-rich part of the Li₂O-Nd₂O₃-Fe₂O₃ system, crystallizes with a cubic unit cell of dimension and the space group Im3m. Refinement on F resulted in R=1.9%. The structure is comprised of a network of corners, edges and faces sharing the coordination polyhedra of neodymium. In between this skeleton the regular octahedra of oxygen-coordinated iron and trigonal prisms of lithium are located. The Mössbauer spectra revealed the presence of Fe³⁺, Fe⁴⁺ and Fe⁵⁺ ions distributed on two symmetry-independent lattice positions.     

Swiemahogins A and B, two novel limonoids from Swietenia mahogani

Two novel limonoids, swiemahogins A (1) and B (2) isolated from the twigs and leaves of Swietenia mahogany, are the first examples of andirobin and phragmalin types of limonoids, of which the D-ring δ-lactone is demolished and a rare γ-lactone is fused to the C-ring at C-8 and C-14. Their structures were elucidated by extensive spectroscopic means, and that of 1 was confirmed by single-crystal X-ray diffraction.     

High energy density compounds from cyclophosphazene. II. The preparation, structural characterization, and theoretical studies of 1,1-spiro(ethylenediamino)-3,3,5,5-tetrachlorocyclotriphosphazene and its nitration product

In this paper, the synthesis principles and methods of 1,1-spiro(ethylenediamino)-3,3,5,5-tetrachlorocyclotriphosphazene (ETCCTP) and its nitration product of 1,1-spiro(N,N′-dinitroethylenediamino)-3,3,5,5-tetrachlorocyclotriphosphazene (DNETCCTP) have been reported. Their structures were demonstrated by elemental analysis, NMR, MS, and FTIR methods. Besides, the crystal of the title compound was obtained and characterized by X-ray single-crystal diffraction technique. The obtained results showed that the crystal belongs to Crystal system of Monoclinic with space group of C2/c. Based on the crystal data, geometries and normal vibrations have been obtained by using the B3LYP method with the 6-31G**, 6-311G**, and 6-31++G** basis sets. The calculation results further demonstrate the molecular structure of the title compound.     

Synthesis,X-ray crystallography characterization,vibrational spectroscopy,and DFT theoretical studies of a new organic–inorganic hybrid material

A new hybrid material based on polyoxomolybdate, [C₂H₆N₂O–H]₃[(PO₄)Mo₁₂O₃₆] · 3H₂O (1), has been synthesized and characterized by elemental analysis, infrared and mass spectroscopy, proton nuclear magnetic resonance and single-crystal X-ray diffraction. Compound 1 crystallizes in the hexagonal system, space group R-3, a = 19.0833(6) Å, c = 20.8672(13) Å, V = 581.1(5) ų, Z = 6, R1 = 0.0202, wR2 = 0.0508. The methyluronium moiety and 12-molybdophosphate anion are held together in a network through hydrogen-bonding and electrostatic interactions. Each methylurea molecule, which is protonated, is stabilized via present strong hydrogen bonding with water molecules in the unit cell. Since this strong hydrogen bonding can play an important role in the formation of unique novelty of titled supramolecular network, we have carried out theoretical calculations on geometrical parameters, stabilization energies, and atomic charges based on natural bond orbital (NBO) analyses and then have compared with those of the neutral methylurea molecule. Our calculations have been done with the B3LYP method of density functional theory (DFT).     

Single-crystal X-ray diffraction analysis of pyrene II at 93 K

The crystal and molecular structure of the low temperature phase of the polycyclic aromatic hydrocarbon pyrene has been determined for the first time by single-crystal X-ray diffraction methods. The crystal structure at 93 K is shown to be in excellent agreement with that obtained by the refinement of powder neutron diffraction data for pyrene II obtained at 4.2 K.     

Triangular antiferromagnetic order in the honeycomb layer lattice of

ErCl₃ crystallizes in the AlCl₃-type layer structure. The crystal structure was refined in the paramagnetic state by powder neutron diffraction. The monoclinic lattice parameters at 1.5 K are a = 6.8040(3)?, b = 11.7456(5)?, c = 6.3187(3)? and . The space group is C2/m. Short-range, predominantly in-plane, magnetic ordering occurs above 350 mK up to several Kelvin. Below mK a three-dimensional antiferromagnetic order with a propagation vector of sets in. The magnetic structure of ErCl₃ was determined by powder and single-crystal neutron diffraction at temperatures down to 45 mK. The Er³⁺ ions are located on two-dimensional honeycomb layers in the a–b plane. There are two antiferromagnetically coupled triangular sublattices which form right- and left-handed helices along the c-axis. The magnetic moments are oriented in the a–b plane and amount to 3.3(1) at saturation. From the temperature dependence of the integrated neutron magnetic peak intensity a critical exponent (2) was derived for the magnetic phase transition. Received 1 December 1999 and Received in final form 21 July 2000     

Ordering phenomena in C<Subscript>60</Subscript>-tetraphenylphosphonium bromide

The fulleride salt C₆₀-tetraphenylphosphonium bromide is investigated as a function of temperature by single crystal X-ray diffuse scattering and diffraction. At room temperature, the C₆₀ orientational disorder is found to be more complex than previously expected. Moreover, a structural phase transition, due to the C₆₀ orientational ordering, is evidenced around 120 K. Its relation with the stabilization of a static Jahn-Teller effect is discussed. Received 3 November 1999     

(Z)-3,3-二甲基-1-(1H-1,2,4-三唑-1-基)-2-丁酮肟(5-芳基-1,3,4-噁二唑-2-基)甲基醚的合成和抑菌活性

以3,3-二甲基-1-（1H-1,2,4-三唑基）-2-丁酮肟为原料,经醚化、肼解及腙化3步反应得到（E）-N'-（取代苯亚甲基）-2-[（Z）-3,3-二甲基-1-（1H-1,2,4-三唑-1-基）丁基-2-亚甲氨氧基]乙酰肼（3a~3u）,化合物3与二乙酸碘苯（IBD）反应,合成了21个（Z）-3,3-二甲基-1-（1H-1,2,4-三唑-1-基）-2-丁酮肟-（5-芳基-1,3,4-噁二唑-2-基）甲基醚（4a~4u）,化合物4的化学结构经核磁共振谱、高分辨质谱和元素分析确证.采用单晶X射线衍射仪测定了化合物4c的晶体结构.抑菌活性测试结果表明,在500 mg/L浓度下,化合物4k,4f,4j和4n对纹枯病菌的防效率分别为70.9%,60.2%,60.0%和60.6%;在25 mg/L浓度下,化合物4b,4c,4d和4e对菌核病菌的抑制率为71.8%~76.9%.     

Structure investigation of fluorinated aluminophosphate ULM-3 Al templated by 3-methylaminopropylamine

A single-crystal X-ray diffraction analysis of an open-framework aluminophosphate ULM-3 Al prepared by 3-methylaminopropylamine (MAPA) as structure-directing agent revealed an orthorhombic Pcab symmetry (a=9.9949(4) Å, b=15.8229(7) Å, c=18.1963(5) Å, R=0.0648, Z=8, unit cell formula [Al₂₄P₂₄O₉₆F₁₆·C₃₂H₁₁₂N₁₆]), which differs from the Pbc2₁ symmetry of the structural analogue prepared in the presence of 1,4-diaminobutane. The ²⁷Al, ³¹P, ¹⁹F, ¹³C and ¹H NMR investigations, which were performed to study in detail MAPA arrangement inside the framework as well as the interactions of MAPA with the aluminophosphate host, confirmed the crystal symmetry and the proposed hydrogen bonding scheme between the template and the framework.     

Growth of single-crystalline sodium titanate and sodium tungstate one-dimensional nanostructures: Bio-inspired approach using oyster shell

Using oyster shell, single-crystalline Na₂Ti₆O₁₃ and Na₂W₄O₁₃ one-dimensional nanostructures (ODNS) were simply synthesized from granular TiO₂ and WO₃ particles by thermal heating at 700 °C. The oyster shell was used as a source of both sodium and carbon dioxide, which have an effect on unidirectional growth of single-crystalline Na₂Ti₆O₁₃ and Na₂W₄O₁₃ from TiO₂ and WO₃. The growth of sodium metal oxide ODNS from metal oxide particles was reproduced by replacing oyster shell with chemical reagents (NaCl, CaCO₃) or gas (CO₂), allowing identification of the main factors for the growth of ODNS. The characteristics of biological material (i.e., oyster shell) lend certain advantages in the fabrication of sodium metal oxide ODNS: (a) low processing temperature with high yield; (b) an eco-friendly method; and (c) no requirement of additional processes such as separation or washing. This work suggests a new approach for using biological material for the crystal growth of nanostructured materials.