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891.
Helmut Spreitzer Edith Rodinger Andrea Pichler Gerhard Buchbauer 《Monatshefte für Chemie / Chemical Monthly》1990,121(11):955-961
Summary The bicyclo[2.2.1]- and [2.2.2]-systems are part of numerous biological active substances. Continuing our syntheses in the isocamphane series the homologous isocamphanes of mecamylamine (1 a) and of the fungicidal bicyclic compound2 were synthesized. Furthermore the syntheses ofE-homoisosantalene (15) andE,E-homoisosantalol (16) are described. 相似文献
892.
Haoshuang Gu Yongming Hu Hao Wang Xiangrong Yang Zhenglong Hu Ying Yuan Jin You 《Journal of Sol-Gel Science and Technology》2007,42(3):293-297
Single crystalline nanowires of lead titanate (PbTiO3) were fabricated by hydrothermal method at 200°C using lead acetate and n-tetrabutyl titanate as starting materials, where sodium hydroxide was served as a mineralizer. Crystalline phases, microstructure
and optical properties of PbTiO3 nanowires were investigated. The PbTiO3 nanowires were uniform and continuous along the long axis, and were composed of single crystalline PbTiO3 with a tetragonal perovskite structure. The diameter of a single nanowire was around 12 nm and the length reached up to 3 μm.
The chemical composition of the samples and the valence states of elements were determined by X-ray photoelectron spectroscopy
(XPS). The ultraviolet/visible absorption spectroscopic investigation suggested that the absorption edge of optical transition
of the first excitonic state occurred at around 320 nm. A blue-green light emission peaking at about 471 nm (2.63 eV) is observed
at room temperature, and the intensity of this emission increased with increasing excitation wavelength. Oxygen vacancies
are responsible for the light emission of PbTiO3 nanowires. 相似文献
893.
Treatment of 1-alkyl-4,5-dichloro-3-nitropyridazin-6-one with C-nucleophiles and with ambident nucleophiles (2-azahetarylacetonitriles)
leads to a selective substitution of a chorine atom by the quaternary carbon atom of the carbanion formed from a substituted
acetonitrile. The pKa of the CH-acid 2-(1-alkyl-5-chloro-3-nitro-6-oxo-1,6-dihydro-4-pyridazinyl)malononitrile was determined by potentiometric
titration. Reaction of 2-(1-alkyl-5-chloro-3-nitro-6-oxo-1,6-dihydro-4-pyridazinyl)-2-hetarylacetonitriles with primary amines
gives 6,7-dihydro-1H-pyrrolo[2,3-d]pyridazin-7-ones.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 556–564, April, 2006. 相似文献
894.
Ya. L. Garazd T. N. Panteleimonova M. M. Garazd V. P. Khilya 《Chemistry of Natural Compounds》2003,39(4):330-336
Mannich bases containing the dialkylaminomethyl group in the 6- and 8-positions of 2,3-di-hydrocyclopenta[c]chromen-4-ones were prepared by condensation of 7- and 9-hydroxy-2,3-dihydrocyclopenta[c]chromen-4-ones with substituted 1,1-diaminomethanes. The effects of 8-chloro-7-hydroxy-6-(1-pyrrolidinylmethyl)-2,3-dihydrocyclopenta[c]chromen-4-one and 8-chloro-7-hydroxy-6-(morpholinomethyl)-2,3-dihydrocyclopenta[c]chromen-4-one on the central and peripheral nervous systemwere defined and enable the presence of tranquilizing and neuroleptic properties to be predicted. 相似文献
895.
Resorc[4]arenes are compounds with interesting properties, mainly because of their ability to form host-guest complexes with the guest located inside the cavity. The size of the guest limits the complexation, as shown by a competition experiment with tetraalkylammonium ions of different size. By electroscopy ionization tandem mass spectrometric experiments on resorc[4]arene heterodimers bearing an alkali metal ion as guest, it was found that there must be two different binding mechanisms for alkali metal ions with high surface charge density (Li(+) and Na(+)) on the one hand compared with those with a lower surface charge density on the other hand (K(+), Rb(+), Cs(+)). 相似文献
896.
From the changes in energy band, density of state (DOS) and electronic structure calculated by the DFT/B3LYP method, the conductivity of carbon doped boron‐nitride nanotube (BNNT), which is formed by C‐C bond substituting B‐N bond, was discussed. The results indicate that the substitution will strengthen the conductivity of the tube, and its semi‐conductivity might be adjusted by controlling the substitution. 相似文献
897.
Shyh‐Jong Chen Cheng Chen Yaw‐Shun Hong 《International journal of quantum chemistry》2005,103(2):198-214
This investigation conducted reaction channels of weakly bound complexes CO2…HF, CO2…HF…NH3, CO2…HF…NH2CH3, CO2…HF…NH(CH3)2, and CO2…HF…N(CH3)3 systems, using the Gaussian 98 package at the B3LYP/6‐311++G(3df,2pd) level. The syn‐fluoroformic acid or syn‐fluoroformic acid plus NH3 or amine conformers are more stable than the related anti‐fluoroformic acid or anti‐fluoroformic acid plus NH3 or amine conformers. However, the above‐mentioned weakly bound complexes are more stable than both the related syn‐ and anti‐type fluoroformic acid or acid plus NH3 or amine conformers and their related decomposed into CO2 + HF or CO2 + NHR3F (R?H, CH3) combined molecular systems. Five reaction channels of the weakly bound complexes exist. Each channel includes weakly bound complexes and their related above‐mentioned systems. Moreover, each reaction channel contains two transition states. The transition state between the weakly bound complex and anti‐fluoroformic acid type structure (T13) is significantly higher than that of internal rotation (T23) between syn‐ and anti‐FCO2H (or FCO2H…NR3) structures. However, the above‐mentioned T13 can significantly decrease its energy by adding the third molecule NH3 or NR3 (R?H or CH3). The more CH3 that is substituted in NR3 of the reaction channel, the lower the activation energy of the transition state in the system is affected. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
898.
F. I. Zubkov E. V. Nikitina K. F. Turchin A. A. Safronova R. S. Borisov A. V. Varlamov 《Russian Chemical Bulletin》2004,53(4):860-872
The intramolecular Diels—Alder reaction of readily accessible 4-substituted 4-(N-furfuryl)aminobut-1-enes was studied and a new one-step method was developed for the synthesis of 6,8a-epoxy-1,2,3,4,4a,5,6,8a-octahydroisoquinoline (3-aza-11-oxatricyclo[6.2.1.01,6]undec-9-ene) derivatives. The [4+2]-cycloaddition proceeds stereoselectively to form exo-adducts. The influence of substituents at the nitrogen atom in 4-(N-furfuryl)aminobut-1-enes on the cycloaddition pathway was examined. 相似文献
899.
用~1HNMR方法研究了溶液中大环化合物1,12-二氮杂-3,4:9,10-二本并-5,8-二氧杂环十五烷-N,N’-二乙酸盐的构象.NMR变温实验表明,在溶液中大环与Zn(Ⅱ)、Ni(Ⅱ)、Co(Ⅱ)的配合物环上醚氧不参与配位,其中Ni(Ⅱ)配合物为低自旋反磁性的平面四方形配位. 相似文献
900.
<正> 聚酯聚醚嵌段共聚物具有十分良好的物理和机械性能,能加工成橡胶、纤维、塑料胶粘剂等,近年来也有作为医用高分子材料的报道。所以对聚酯聚醚嵌段共聚物的研究十分活跃。然而,有关其光物理性质的研究还很少见。本文报道了混合聚醚-聚酯嵌段共聚物(MPEE)与反式1,4-二咔唑环丁烷(1,4-DCC)在激发态和基态下的相互络合作用。结果表明,MPEE可以猝灭1,4-DCC的荧光,同时形成激基复合物。在分散 相似文献