排序方式: 共有11条查询结果,搜索用时 62 毫秒
1.
Ian R. Pottie C. V. Krishnamohan Sharma Keith Vaughan Michael J. Zaworotko 《Journal of chemical crystallography》1998,28(1):5-10
The crystal and molecular structure of 1,2-bis-{1-(2-cyanophenyl)-3-methyltriazen-3-yl-}ethane (1) and 1,2-bis-{1-(2-methoxyphenyl)-3-methyltriazen-3-yl-}ethane (2) have been determined by single crystal X-ray diffraction analysis. Bis-triazene (1) exists as the staggered conformation in the solid state, with an anti-anti configuration around the N2–N3 bond of the triazene units, whereas 2 assumes a gauche conformation with the syn-syn configuration in the triazene units. Crystal data: 1 C18H18N8, triclinic, space group P –1, a = 6.108(2), b = 8.118(3), c = 9.600(4)Å, = 101.37(7)°, = 96.47(7)°, = 102.71(5)°, V = 449.1(3)Å3, Z = 2; 2 C18H24N6O2, monoclinic, space group P 21/n, a = 13.119(5), b = 7.745(2), c = 19.201(2)Å, = 96.47(7)°, V = 1910.3(9)Å3, Z = 4. 相似文献
2.
O. Morizot L. Longchambon R. Kollengode Easwaran R. Dubessy E. Knyazchyan P.-E. Pottie V. Lorent H. Perrin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):209-214
We discuss the quality required for the RF source used to trap neutral atoms in RF-dressed potentials. We illustrate this
discussion with experimental results obtained on a Bose-Einstein condensation experiment with different RF sources. 相似文献
3.
T Hamoir D Courtheyn H De Brabander P Delahaut L Leyssens G Pottie 《The Analyst》1998,123(12):2621-2624
Within several regional field laboratories and the national reference laboratory a harmonised methodology for the analysis of anabolic residues in faecal samples was developed. The method consists of a liquid-liquid and a solid-phase extraction step, followed by a high-performance liquid chromatography purification step. Using gas chromatography-mass spectrometry, currently illegally used anabolic steroids can be detected in faeces at the ppb level. Within this context acidification, followed by centrifugation under cooling, allows efficient, practical and rapid defatting of faecal samples. Furthermore, a combination of a silica and an aminopropyl solid-phase extraction column was found to give the best results as regards the sample purification process. 相似文献
4.
A convenient method for the sampling and total analysis of the propellents and active agents contained in aerosol irritant projectors has been developed. A gas chromatograph equipped with a column packed with 6% Carbowax 20M on Chromosorb G and coupled to a mass spectrometer provides both quantitative and qualitative analysis for the components of a typical irritant projector. The main lachrymator, bromoacetone, represented 1.5% and the propellents dichlorodifluoromethane and trichlorofluoromethane, comprised 97.7% of the aerosol mixture. 相似文献
5.
Trimethylsilyl methylenenitronate reacts with both aliphatic and aromatic aldehydes in the presence of catalytic amounts of scandium(III) triflate to form the Henry reaction products in low (25%) to good yields (77%). This is the first example of this silyl nitronate undergoing a nitro-aldol reaction under an acid environment. 相似文献
6.
7.
Pottie IR Nandaluru PR Benoit WL Miller DO Dawe LN Bodwell GJ 《The Journal of organic chemistry》2011,76(21):9015-9030
A set of coumarin-fused electron-deficient 1,3-dienes was synthesized, which differ in the nature of the electron-withdrawing group (EWG) at the terminus of the diene unit and (when EWG = CO(2)Me) the nature and position of substituents. These dienes reacted with the enamine derived from cyclopentanone and pyrrolidine to afford the corresponding cyclopenteno-fused 6H-dibenzo[b,d]pyran-6-ones, most likely via a domino inverse electron demand Diels-Alder (IEDDA)/elimination/transfer hydrogenation sequence. The parent diene (EWG = CO(2)Me, no substituents) was reacted with a range of electron-rich dienophiles (mostly enamines) to afford the corresponding 6H-dibenzo[b,d]pyran-6-ones or their nondehydrogenated precursors, which were aromatized upon treatment with a suitable oxidant. The enamines could either be synthesized prior to the reaction or generated in situ. The syntheses of 30 dibenzopyranones are reported. 相似文献
8.
Ian R. Pottie Keith Vaughan Michael J. Zaworotko 《Journal of chemical crystallography》2001,31(3):143-148
Diazotization of p-aminobenzonitrile and coupling of the resulting diazonium salt with N,N-dimethylethylenediamine affords a novel material that has been shown by X-ray crystallography to be a cocrystal (3) of the pentaazadiene (1) and the diaryltriazene (2). Crystal data: monoclinic, space group P21/c, a = 9.363(5), b = 21.509(3), c = 15.862(5) Å, = 98.86(5)°, V = 3156.3(18) Å3, Z = 4, R
w = 0.035, R
int = 0.037. The pairing of the two molecules 1 and 2 appears to represent a unique molecular recognition event involving a combination of hydrogen bonding and – stacking. The crystal structure shows that the N–H of the triazene is within hydrogen-bonding distance of the tertiary nitrogen atom in the alkyl side-chain of the pentazadiene; furthermore, the benzene rings of the triazene and the pentazadiene are stacked off-register and separated by 3.53 Å. The formation of the components of the cocrystal is rationalised in terms of the formation and decomposition of the 1-aryl-3-alkyltriazene, Ar–N=N–NH–CH2CH2NH2. 相似文献
9.
We present what is to our knowledge the first observation of spin-polarized atoms cooled within a reflecting cylinder in a high-power medium. A low-pressure vapor of cesium atoms is stored in a glass cell whose volume is 58 cm(3). Cooling laser light (lambda=852 nm) is injected into the cell by optical fibers and is recycled by multiple reflections from the walls of the cylinder. The technique used in this experiment greatly simplifies the generation of laser-cooled atoms. A maximum of 2.5 x 10(8) cold atoms was detected by a time-of-flight technique. The damping of atomic motion has lead to temperatures as low as 3.5muK . 相似文献
10.
Olivier Lopez Amale Kanj Paul-Eric Pottie Daniele Rovera Joseph Achkar Christian Chardonnet Anne Amy-Klein Giorgio Santarelli 《Applied physics. B, Lasers and optics》2013,110(1):3-6
In this work, we demonstrate for the first time that it is possible to transfer simultaneously an ultra-stable optical frequency and precise and accurate timing over 540 km using a public telecommunication optical fiber network with Internet data. The optical phase is used to carry both the frequency information and the timestamps by modulating a very narrow optical carrier at 1.55 μm with spread spectrum signals using two-way satellite time transfer modems. The results in terms of absolute time accuracy (250 ps) and long-term timing stability (20 ps) well outperform the conventional Global Navigation Satellite System or geostationary transfer methods. 相似文献