A New Ketone Derivative from Victoria amazonica

Chemistry of Natural Compounds - A new ketone, vicamazone (4-(2-butoxyethoxy)-4-methylpentan-2-one) (1), was isolated from the leaves of Victoria amazonica (Nymphaeaceae). The structure of the new...     

Secondary Metabolites of Elaeagnus thunbergii

Chemistry of Natural Compounds -     

Synthesis of 4‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)phenyl‐hydrazine derivatives from 3‐(4‐hydrazinocarbonyl‐phenyl)sydnones

The synthesis of potential fluorescent active 4‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)phenylhydrazine derivatives was accomplished in three steps. The key step was the dehydration cyclization of 1,2‐diacylhydrazines to form the 1,3,4‐oxadiazole ring by use of acetic anhydride/perchloric acid mixture as the dehydrating agent. The sydnone moiety served as the masked hydrazines, which could be demasked by HCl for further application. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:438–442, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20318     

Electrophoresis of a rigid sphere in a Carreau fluid normal to a large charged disk

The electrophoresis of a rigid sphere in a Carreau fluid normal to a large disk is analyzed theoretically under the conditions of low surface potential and weak applied electric field. Previous analyses are extended to the case where a disk can be charged, and a more realistic electrostatic force formula is applied. We show that the qualitative behavior of a sphere depends largely on its distance from a disk, the thickness of double layer, and the nature of a fluid. In general, the presence of a disk has the effect of increasing the conventional hydrodynamic drag on a sphere, and a decrease in the thickness of the double layer surrounding a sphere has the effect of enhancing the shear-thinning effect. However, this might not be the case if a sphere is uncharged and a disk is charged, where the osmotic pressure field and the induced charge on the sphere surface can be significant. The shear-thinning effect is important only if the thickness of double layer is sufficiently thick. This result can play a significant role in practice such as in electrophoretic deposition, where the deposition electrode is charged and the fluid medium is usually of shearing-thinning nature.     

Topological analysis of some special graphs: III. Regular polyhedra

A regular polyhedron is isomorphic to a cluster on which every face has same number of bonds and every atom has an equal number of coordinating atoms. A general strategy for generating the eigenvectors and the eigenvalues of regular polyhedra is given. Not sign analyses are also performed on the eigenvectors of regular polyhedra. The results provide us a quick way to grasp the topological feature of the electronic structure of clusters having interesting topology.     

3-Substituted Sydnone Derivatives. Structures of 3-Cyclohexylsydnone and of Two Forms of 3-(3-Pyridyl)sydnone

The crystal and molecular structures of three sydnone derivatives are reported. The compound 3-cyclohexylsydnone crystallizes in space group C2/c of the monoclinic system with sixteen molecules in a cell of dimensions a = 19.326 (3), b = 9.471 (2), c = 20.005 (4)Å, β = 106.85(1)°. The structure has been refined to a final value of 0.0581 for the conventional R-factor based on 2222 independent observed intensities. Form I of 3-(3-pyridyl)sydnone crystallizes in space group P2/n of the monoclinic system with eight molecules in a cell of dimensions a = 7.317(2), b = 9.283 (2), c = 20.891 (6) Å, β = 99.61(2)°. The structure has been refined to a final value of 0.0514 for the conventional R-factor based on 1208 independent observed intensities. Form II of 3-(3-pyridyl)sydnone crystallizes in space group P2₁/c of the monoclinic system with eight molecules in a cell of dimensions a=9.073 (2), b = 22.267 (5). c = 7.494(2)Å, β = 112.15 (2)°. The structure has been refined to a final value of 0.0462 for the conventional R-factor based on 1330 independent observed intensities. Each of the three structures contains two crystallographically independent molecules in the cell. In the case of 3-cyclohexylsydnone, one of the independent molecules exhibits disorder around the exocyclic bond at N(3). A comparison of bond lengths indicates that the (electron donating) cyclohexyl group brings about enhanced electron density in the N(3)-C(4) bond, and possibly in the N(3)-N(2) bond. All three structures studied here exhibit intermolecular hydrogen bonding involving C(4)-H(4)…O(6) interactions. Although there are no stacking interactions in the cyclohexyl derivative, there is evidence for such interactions in the 3-pyridyl derivatives.     

Acyl and α-Ketoacyl Complexes of Pt(II) with Weak Donor Ligands

Treatment of trans-Pt(COCOPh)(Cl)(PPh₃)₂ (1a) with AgBF₄in THF led to the formation of a metastatic complex trans-[Pt(COCOPh)(THF)(PPh₃)₂](BF₄) (2) which readily underwent ligand substitution to give a cationic aqua complex trans-[Pt(COCOPh)(OH₂)(PPh₃)₂](BF₄) (5a). Complex 5a has been characterized spectroscopically and crystallographically. Analogous reaction of trans-Pt(COCOOMe)(Cl)(PPh₃)₂ (1b) with Ag(CF₃SO₃) in dried CH₂C1₂ was found first to yield a methoxyoxalyl triflato complextrans-Pt(COCOOMe)(OTf)(PPh₃)₂ (6). Attempts to crystallize the triflato product in CH₂-cl₂hexane under ambient conditions also afforded an aqua complex of the triflate salt f/wu-[Pt(COCOOMe)(OH₂)(PPhj)₂](CF₃SO₃) (5b). Complex 5a in a noncoordinating solvent such as CH₂C1₂ or CHCl₃ suffered spontaneous decarbonylation to form first cis-[Pt(COPh)(CO)(PPh₃)₂l(BF₄) (3a) then the thermodynamically stable isomer trans-[Pt(COPh)(CO)(PPh₃)₂](BF₄) (3b). Crystallization of complex 3b under ambient conditions resulted in an aqua benzoyl complex trans-[Pt(COPh)(OH₂)(PPh₃)₂](BF₄) (7). The replacement of the H_2O ligand in complex 7 by CO was done simply by bubbling CO into the solution of 7. The single crystal structures of 5b and 7 have been determined by X-ray diffraction. The distances of the Pt-O bonds in 5a, 5b, and 7 support that the aqua ligand is a weak donor in such cationic aquaorganoplatinum(lI) complexes, in agreement with their lability to the substitution reactions.     

On the first excited state of137Ba

The first excited state of¹³⁷Ba has been excited by the inelastic scattering of accelerator-produced neutrons. The energy of this state at 283.5 keV is not in agreement with the generally accepted value of 279.2 keV, but is in accord with other recent measurements. No evidence for a doublet of states near this energy is found.     

TiO_2纳米管阵列的多重改性及其在超级电容器中应用的最新进展

阳极氧化法制备的TiO_2纳米管阵列因其简单的制备方法、可控的形貌以及环境友好等优点而成为超级电容器领域重点研究的电极材料之一。本文介绍了TiO_2纳米管的多重改性方法,包括引入氧空位、金属或非金属修饰或掺杂、金属化合物(氧化物、氢氧化物、硫化物、氮化物)以及导电聚合物修饰等,以进一步提高TiO_2纳米管的电化学性能。介绍了近年来阳极氧化法制备的TiO_2纳米管阵列在超级电容器中应用的研究进展,为进一步拓展TiO_2纳米管阵列的实际应用提供参考。