ADVANCES IN STUDY OF A NEW CLASS OF PILLARED LAYERED MICROPOROUS MATERIALS?¤?¤POLYOXOMETALATE-TYPE HYDROTALCITE-LIKE CATALYSTS

In the present paper, on the basis of our work. advances in study of the catalysts of polyacid-type hydrotalcite-like are reported and reviewed. Using polyoxometalates (POM) as pillaring species and layered double hydroxides (LDH) as host matter, a new class of catalytic materials, LDHPOM, has been synthesized by five different methods. Their acidic and oxidative catalytic properties have been investigated by several research groups. The above mentioned information is given in this review.     

铜(Ⅰ)配合物[Cu(C8H4O2F3S)(PPh3)2]合成、性质、晶体结构及反应机理的探讨

Reaction of copper powder with 2-thenoyltrifluoroacetone and PPh₃ yielded the complex [Cu(C₈H₄O₂F₃S)(PPh₃)₂], which have been characterized by elemental analysis and IR spectra. The crystal is monoclinic, space group P2₁/n , a=1.0584(1), b=1.6738(1), c=2.2728(9) nm; β =94.22(2); V =4.0152 nm 3; Z=4; D_c=1.299 g·cm^-3; R=0.048, R_W=0.054. Copper (Ⅰ) ion is coordinated by two O and two P atoms forming distorted tetrahedron.     

测接触角法确定偶联剂的最佳用量

偶联剂是一类能在无机填料和聚合物基材之间形成“分子桥”、改善两者之间相容性或提高两者之间相互作用能力的化合物。将经偶联剂改性的无机填料填充到聚合物中可以制得成本低、性能好的复合材料。由于偶联剂用量多少将对复合材料的性能产生较大影响,因此建立一种准确、简便地确定偶联剂最佳用量的方法有着十分重要的理论和实际应用意义。     

新马兜铃内酯的晶体结构

从绵毛马兜铃的根茎中分离出一种新的倍半萜内酯, 它的分子式由高分辨质谱数据确定为C~1~5H~2~0O~2, 它的结构用单晶X射线衍射法测定, 晶体属三斜晶系, 空间群为P1, a=0.6275(3)nm, b=0.8057(4)nm, c=1.3622(6)nm; α=88.78(4)°,β=91.44(4)°, γ=105.20(4)°; Z=2.3107。     

Structural changes by sulfoxidation of phenothiazine drugs

Summary The side-chain conformations of psychoactive phenothiazine drugs in crystals are different from those of biologically inactive ring sulfoxide metabolites. This study examines the potential energies, molecular conformations and electrostatic potentials in chlorpromazine, levomepromazine (methotrimeprazine), their sulfoxide metabolites and methoxypromazine. The purpose of the study was to examine the significance of the different crystal conformations of active and inactive phenothiazine derivatives, and to determine why phenothiazine drugs lose most of their biological activity by sulfoxidation. Quantum mechanics and molecular mechanics calculations demonstrated that conformations with the side chain folded over the ring structure had lowest potential energy in vacuo, both in the drugs and in the sulfoxide metabolites. In the sulfoxides, side chain conformations corresponding to the crystal structure of chlorpromazine sulfoxide were characterized by stronger negative electrostatic potentials around the ring system than in the parent drugs. This may weaken the electrostatic interaction of sulfoxide metabolites with negatively charged domains in dopamine receptors, and cause the sulfoxides to be virtually inactive in dopamine receptor binding and related pharmacological tests.     

Ein Beitrag über Oxide vom Typ AMO4 (A = Ti3+, Cr3+; M = Nb5+, Ta5+)

A Contribution on Ternary Oxides of the AMO₄-Type (A = Ti³⁺, Cr³⁺; M = Nb⁵⁺, Ta⁵⁺ ) CrNbO₄, CrTaO₄, TiNbO₄, and TiTaO₄ were prepared by CO₂-laser technique. X-ray single crystal investigations show a random distribution of the metal ions in Rutil type structure, space group D–P4₂/mnm. Calculations of the free energy of reaction between Ti₂O₃ and Nb₂O₅ show higher stability of TiO₂ beside NbO₂. In TiNbO₄ both metals exhibit the oxidation state +4.     

离聚体的结构表征——Ⅴ.含氟离聚体中离子微区稳定性的研究

本文用DSC方法研究了羟酸型含氟离聚体中不同金属离子种类、可离子化基团含量、配位结构单元构型及离子微区大小对离聚体中离子微区稳定性的影响。实验表明:离聚体中金属离子配位能力愈强,羟酸含量愈高,离子微区尺寸愈大,则相应离聚体中离子微区稳定性愈大。铅高聚体>锌离聚体>钙离聚体>钠离聚体。     

Semicarbazones and thiosemicarbazones,XII: Crystal structure of salicylaldehyde semicarbazone

Summary The crystal and molecular structure of salicylaldehyde semicarbazone was obtained by single crystal X-ray diffraction. The O atom of the semicarbazone fragment isanti to the N atom of the hydrazinic group. The distribution of bond lengths in the semicarbazone fragment indicates delocalization of the -electrons. The crystal structure is stabilized by intra- and intermolecular hydrogen bonds.

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Semicarbazone und Thiosemicarbazone, 12. Mitt.: Die Kristallstruktur des Salicylaldehyd-Semicarbazons

Zusammenfassung Die Kristallstruktur und die molekulare Struktur des Salicylaldehyd-Semicarbazons wurde über Einkristall-Röntgenstreuung ermittelt. Das O-Atom des Semicarbazonteils stehtanti zum N-Atom der Hydrazin-Gruppierung. Die Bindungslängen in der Semicarbazoneinheit zeigen eine Delokalisierung der -Elektronen an. Die Geometrie der Verbindung wird durch stabilisierende intra- und intermolekulare Wasserstoffbrückenbindungen bestimmt.

     

Investigation of gas chromatographic interaction mechanism on permethylated cyclodextrins by molecular modelling

Summary The capillary gas chromatographic retention behavior of -pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before -pinene; only permethylated -cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated -cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.