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71.
B. T. Ibragimov S. A. Talipov T. F. Aripov 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(4):317-324
The structures of gossypol complexes are extremely sensitive to the halogenomethane present as the guest; e.g. changing the number of Cl atoms in chloromethane derivatives changes the structure of the gossypol complex. The crystals of C30H30O8·CH2Cl2 are monoclinic, space groupC2/c,a=21.320(4),b=19.199(6),c=15.765(2)Å, =113.05(2)o,V=5916(2)Å3,Z=8,D
x=1.35 g/cm3,T=295 K. The structure has been solved by direct methods and refined to the finalR value of 0.084 for 1828 reflections. In the structure H-bonded gossypol molecules form columns, generating channels in the structure which are filled by guest molecules. After decomposition (desolvation) monocrystals of the complexes are conserved without destruction, in which there are rather wide and empty channels though slightly smaller than in the complex. An attempt is made to explain some peculiarities of the behavior of the gossypol polymorph formed on the basis of its structure with empty channels.
Supplementary data relevant to this article have been deposited with the British Library Publication No. SUP 82165 (17 pages). 相似文献
72.
A. N. Chekhlov 《Journal of Structural Chemistry》2005,46(1):182-184
The crystal and molecular structure of tris(m-chlorophenyl)phosphine selenide, C18H12Cl3PSe (I), was investigated by X-ray diffraction (XRD) analysis. The trigonal rhombohedral structure of I (space group \(R\overline 3 c\), a = 14.110(2) Å, c = 32.360(4) Å, Z = 12) was solved by direct methods and refined by least squares in an anisotropic approximation (R = 0.029) for 1319 averaged measured reflections (CAD-4 automatic diffractometer, λCuKα). 相似文献
73.
Haishan Bu Erqiang Chen Shengyong Xu Kexin Guo Bernhard Wunderlich 《Journal of Polymer Science.Polymer Physics》1994,32(8):1351-1357
Single-molecule single crystals were grown from amorphous droplets of fractionated isotactic polystyrene. The crystals were analyzed by electron microscopy and electron diffraction. The molecular mass distribution could be matched with a statistical analysis of single-molecule particles (amorphous and crystals). Proof was brought that single molecules of isotactic polystyrene do not reach equilibrium dimensions on crystallization, rather assume the lamellar morphology with chain-folded macroconformation, also known from crystallization of polymolecular crystals. © 1994 John Wiley & Sons, Inc. 1 This article is a US Government work and, as such, is in the public domain in the United States of America. US Government contract No. DE-AC05-840R-21400. 相似文献
74.
单分散纳米InVO4(正交相)的低温合成 总被引:1,自引:0,他引:1
InVO4 is a new developed visible light responding photocatalyst for water decomposition, which is obtained by a solid-state reaction at high temperature traditionally. In this paper, pure InVO4 nano-crystalline powder has been prepared by a hydrothermal process at low temperature and was characterized by TEM, IR, and X-ray diffraction. Many factors such as pH value, reaction time and temperature have been investigated. It is found that the optimal conditions for the preparation is: nInCl3∶nNaVO3=1∶2; temperature : 150 ℃; Reaction time: 4~8 h; pH=7.9~8.0. And the experimental result shows that it is a convenient way to get single dispersing InVO4 nano-crystalline powder by flux in alkyl alcohol. 相似文献
75.
Artificial cerebrospinal fluid (c.s.f.) containing 40 mmol/L excess calcium was perfus-ed through the lateral ventricles of New Zealand white rabbits in order to reduce the Na~+/Ca~(++) ratio in the brain and the effects on both the febrile response and adenosine cyclic mo-nophosphate (cAMP) concentration in plasma and c.s.f, during leucocytic pyrogen (LP)-induced fever were observed. The results showed that cAMP concentration in c.s.f, increas-ed significantly during LP-induced fever while the cAMP level in Plasma remained unchang-ed, and the perfusion of artificial c.s,f, containing 40 mmol/L excess calcium can signif-icantly inhibit not only the febrile response but also the increase in c.s.f, cAMP level,while there appears no effect on plasma cAMP concentration, thus demonstrating that theincrease of Na~+/Ca~(++) ratio causing the increase of cAMP content in the brain may be anessential link in the pathogenesis of LP-induced fever. 相似文献
76.
Li-Juan Jia Yuan-Yuan Wang Hui Chen Yong-Kui Shan Li-Yi Dai 《Reaction Kinetics and Catalysis Letters》2005,86(2):267-273
Summary The alkylation of benzene with 1-hexene has been investigated in different triethylamine hydrochloride-ferric chloride (Et3NHCl-FeCl3) and triethylamine hydrochloride-aluminium chloride (Et3NHCl-AlCl3) ionic liquids. Both high catalyst activity and monoalkylation selectivity were observed for these two type of ionic liquids.
Systems prepared by modification with HCl in Et3NHCl-FeCl3ionic liquids prove to be very suitable solvents and catalysts for the reaction. When employing Et3NHCl-AlCl3ionic liquids as catalysts, the reaction takes place in biphasic mode with facile catalyst separation and catalyst recycling. 相似文献
77.
Itsuo Furuoya 《Catalysis Surveys from Japan》1999,3(1):71-73
The vapor phase catalytic reaction between aromatic carboxylic acid and acetic acid was investigated. Many metal oxides catalyzed the reaction between 2methylbenzoic acid (OTA) and acetic acid (AA) to produce 2methylacetophenone (OMA), and weakly acidic oxides such as Th, U, Ce, and La oxide exhibited higher yield of OMA. The OMA yield depended on the catalyst support. SiO2, Al2O3, TiO2, and ZrO2 with a surface area of less than 200 m2 g–1 appeared to be suitable as industrial catalyst supports. CeO2 on Al2O3was chosen as an industrial catalyst for the synthesis of OMA because of higher productivity, longer catalyst life, and lifting of legal restrictions on catalyst handling. This catalyst system can also be applied to the syntheses of acetophenone, nitroacetophenone, and chloroacetophenone. 相似文献
78.
Sylvia Jeney Ernst H K Stelzer Helmut Grubmüller Ernst-Ludwig Florin 《Chemphyschem》2004,5(8):1150-1158
A new method combining three-dimensional (3D) force measurements in an optical trap with the analysis of thermally induced (Brownian) position fluctuations of a trapped probe was used to investigate the mechanical properties of a single molecule, the molecular motor kinesin. One kinesin molecule attached to the probe was bound in a rigorlike state to one microtubule. The optical trap was kept weak to measure the thermal forces acting on the probe, which were mainly counterbalanced by the kinesin tether. The stiffness of kinesin during stretching and compression with respect to its backbone axis were measured. Our results indicate that a section of kinesin close to the motor domain is the dominating element in the flexibility of the motor structure. The experiments demonstrate the power of 3D thermal fluctuation analysis to characterize mechanical properties of individual motor proteins and indicate its usefulness to study single molecule in general 相似文献
79.
Single Crystal Investigations on Fluoroperovskites MPdF3 (M = Rb, K) and PdF2 Single crystal investigations on PdF2 (violet) confirm the tetragonale rutile structure [1, 2] with a = 495.44(3) pm, c = 338.48(3) pm, Z = 2, space group P42/mnm-D (No. 136) (xF = 0.3058(8)). RbPdF3 and KPdF3 have been obtained. RbPdF3 and KPdF3 both ruby-red single crystals crystallize cubic (perovskite-structure), space group Pm3m-O (No. 221) with a = 429.41(8) pm (RbPdF3) respectively a = 424.30(4) pm (KPdF3). 相似文献
80.
Single crystals of (NMe4)(HF2) were obtained during attempted recrystallization of NMe4F from fluoroolefin. X‐ray diffraction data show that (NMe4)(HF2) crystallizes in the orthorhombic space group Pmmn with unit cell dimensions a = 6.535(2), b = 8.688(3), and c = 5.333(2) Å. The symmetric and virtually linear HF2 anions exhibit a short F···F distance of 2.256(2) Å. The both crystal structures of (NMe4)(H2F3) (orthorhombic, Pbca, a = 8.509(1), b = 11.273(2), and c = 14.880(2) Å) and CsH2F3 (orthorhombic, P212121, a = 7.345(3), b = 9.126(4), and c = 11.444(4) Å) contain dihydrogentrifluoride anions, H2F3?, which have a bent shape and F···F distances of 2.30‐2.34Å. 相似文献