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991.
992.
The title compound,3β-acetoxy-20(29)-lupen-28-aldehyde,is a pentacyclic triterpene which was first isolated from the acetyl acetate fraction of Platanus acerifolia Willd bark and characterized by 1 H-NMR and 13 C-NMR.Besides,the crystal of the compound was acquired,and the relative configuration of 3β-acetoxy-20(29)-lupen-28-aldehyde was determined by single-crystal X-ray diffraction analysis for the first time.It crystallizes in the monoclinic system,space group C2 with a=14.428(3),b=6.6620(13),c=30.399(6),β=103.73(3)°,Z=4,C32 H50 O3,M r=482.72,Dc =1.130 g/cm 3,V=2838.5(10)3,μ(MoKa)=0.070 mm-1,F(000)= 1064,the final R=0.0657 and wR=0.1855 for 2839 independent reflections (R int=0.0802)and 1963 observed ones (I>2(I)).Intramolecular van der waals force contributes to the stability of the structure. 相似文献
993.
The first synthesis and structural characterization by X-ray crystallography of racemic 2,2'-dihydroxy-[1,1']binaphthalenyl-3,3'-bis-hydroxamic acids were reported.The com-pound(C28H30N4O8,Mr = 550.56) crystallizes in orthorhombic system,Fdd2 space group with a = 13.055(3),b = 34.871(7),c = 12.570(3) ,V = 5722(2) 3,Z = 8,Dc = 1.278 g/cm3,λ = 0.71073 ,μ(MoKα) = 0.095 mm-1,F(000) = 2320,S = 1.021,R = 0.0349 and wR = 0.0802 for 1757 observed reflections with I > 2σ(I).The N-H and O atom are involved in two-dimensional intermolecular hydrogen bond nets,which further stabilize the structure. 相似文献
994.
Chuanzhou Tao Feng Liu Weiwei Liu Youmin Zhu Yafeng Li Xiaolang Liu Jing Zhao 《Tetrahedron letters》2012,53(52):7093-7096
A catalytic protocol was developed to synthesize N-aryl-d-glucosamines from the corresponding aryl halides. Cross-coupling of 1,3,4,6-tetra-O-benzyl-β-d-glucosamine with aryl iodides or bromides was catalyzed with copper. Subsequent deprotection of the benzyl group gave the arylation product N-aryl-d-glucosamines. 相似文献
995.
The stable dinuclear [Cu(μ‐C2O4)Cu]2+ entity is facially coordinated at each end by a N‐nitrile functionalized triazamacrocycle, 1, 4, 7‐tris(cyanomethyl)‐1, 4, 7‐triazacyclononane ( L ), to generate a centrosymmetric compound [Cu2 L 2(μ‐C2O4)](ClO4)2 · 4DMF ( 1 ) containing a bis‐bidentate oxalate bridge. The variable‐temperature magnetic measurement for the crystallographically characterized compound exhibits quite strong antiferromagnetic coupling interaction between two oxalate‐linked CuII atoms separated by 5.149 Å with a singlet‐triplet energy gap of –345.5 cm–1. On the other hand, a mononuclear CoIII compound [Co L (N3)3] · 2.5H2O ( 2 ) with monodentate azide terminal groups was synthesized. Structural elucidation by X‐ray diffraction shows that the compound has crystallographically imposed C3 symmetry. Enantiomerically pure crystals were obtained upon crystallization indicated by a Flack parameter of 0.04(5). 相似文献
996.
A microporous and noninterpenetrated metal-organic framework [Cu(3)(L)(2)(DABCO)(H(2)O)]·15H(2)O·9DMF (1) has been synthesized using two different ligands, [1,1':3',1″-terphenyl]-4,4″,5'-tricarboxylic acid (H(3)L) and 1,4-diazabicyclo[2.2.2]octane (DABCO). As revealed by variable-temperature powder X-ray diffraction (VT-PXRD) measurements, N,N'-ditopic DABCO plays an important role for stabilization of the Cu-L framework. The three-dimensional framework of 1 exhibits high stability and excellent adsorption capacity for H(2) (54.3 mg g(-1) at 77 K and 20 bar), CO(2) (871 mg g(-1) at 298 K and 20 bar), CH(4) (116.7 mg g(-1), 99 cm(3) (STP) cm(-3) at 298 K and 20 bar), and n-pentane (686 mg g(-1) at 298 K and 1 bar). Interestingly, the excellent selectivity toward CO(2) over N(2) at ambient temperature (273 and 298 K) and 1 bar makes complex 1 possess practical application in gas separation and purification. 相似文献
997.
Hu YX Ma HB Zheng B Zhang WW Xiang S Zhai L Wang LF Chen B Ren XM Bai J 《Inorganic chemistry》2012,51(13):7066-7074
Three porous supramolecular isomers (IZE-1, IZE-2, and IZE-3) with the same framework component [Zn(2)(EBTC)(H(2)O)(2)] (EBTC = 1,1'-ethynebenzene-3,3',5,5'-tetracarboxylate) were successfully constructed by finely tuning the reaction condition. Although both IZE-1 and IZE-2 are constructed from the linear EBTC subunits and one kind of regular [Zn(2)(CO(2))(4)] paddlewheels, their frameworks exhibit two different (3,4)-c net of fof (sqc1575) and sqc1572, respectively, resulting in cavities with different size and shape. However, as for isomer IZE-3, the EBTC ligands are bent and one-half of the [Zn(2)(CO(2))(4)] paddlewheels are distorted, leading to a novel (3,4,4)-c hyx net with point symbol (6.7(2))(4)(6(2).8(2).10(2))(7(2).8(2).11(2)) and vertex symbol (6.7.7)(4)(7(2).7(2).8.8.12.12)(6.6.8.8.10(2).10(2)). Quantum chemical calculations by DFT indicate that the three isomers have very close thermodynamic stabilities, which may explain that subtle condition change leads to variation of the frameworks. Further theoretical semiempirical investigation on the interactions between solvent molecules and compounds shows different hydrogen binding patterns in good agreement with the experimental observations. Furthermore, they exhibit good solid-state luminescence properties with long lifetime. 相似文献
998.
State-to-state photodissociation dynamics of H(2)O in its B band has been investigated quantum mechanically on a new set of non-adiabatically coupled potential energy surfaces for the lowest two (1)A' states of H(2)O, which are developed at the internally contracted multi-reference configuration interaction level with the aug-cc-pVQZ basis set. Quantum dynamical calculations carried out using the Chebyshev propagator yield absorption spectra, product state distributions, branching ratios, and differential cross sections, which are in reasonably good agreement with the latest experimental results. Particular focus is placed here on the dependence of various dynamical observables on the photon energy. Detailed analyses of the dynamics have assigned the diffuse structure in absorption spectrum to short-time recurring dynamics near the HOH conical intersection. The non-adiabatic dissociation to the ground state OH product via the HOH conical intersection is facile, direct, fast, and produces rotationally hot OH(X?) products. On the other hand, the adiabatic channel on the excited state leading to the OH(A?) product is dominated by long-lived resonances, which depend sensitively on the potential energy surfaces. 相似文献
999.
Biodiesel, chemically consists of fatty acid methyl ester (FAME) produced by methanolysis of natural triglycerides, such as animal fats and vegetable oils, is a kind of biomass energy, which is renewable and ecofriendly. In this article, KF/CaO was used as solid base catalyst for transesterification of soya bean oil and methanol, while ultrasound as supplementary means. Compared to mechanical stirring, ultrasound treatment is an effective method to increase the yield of FAME and shorten reaction time. By single-factor method, the optimisation of reaction conditions has been studied. The research showed that the optimum reaction conditions were: w(catalyst)/w(oil): 3%, reaction temperature: 65°C, n(methanol)/n(oil): 12, reaction time: 1?h, sound intensity: 1.01?W?cm(-2), frequency: 20?kHz, the yield of FAME could be 97%. 相似文献
1000.
The title compound was prepared by the solid state reaction of stoichiometric amounts of CdCl2·H2O and 4-nitroaniline . The crystal used for X-ray analysis was obtained by slow evaporation of an ethanol-aqueous solution of the solid state reaction at room temperature. The structure of compound was characterized by X-ray diffraction analysis. The crystal belongs to orthorhombic, space group Pbca, a=0.77864(7)nm,b=0.72547(6)nm,c=3.3126(2)nm,Z=4,V=1.8712(3)nm3,Dc=1.890g·cm-3,μ=1.763mm-1, F(000)=1048,R=0.0300,wR=0.0697. The title compound is a typical two-dimensional organic intercalated compound. The inorganic layers of the compound are formed by CdCl6 octahedra sharing corner Cl atoms (i.e. catena-poly[dihlorocadmium-di-μ-chloro]). The organic ammonium cations are intercalated between every two metal-halogen layers and formed the organic layers of the compound through hydrogen bonding. 相似文献