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1.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
2.
Gene‐Hsiang Lee Hsin‐Ta Wang 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):m216-m219
N,N′‐Bis(4‐pyridylmethyl)oxalamide, C14H14N4O2, exists as a dimer which is extended into a two‐dimensional network with other dimers through pyridine–amide hydrogen bonds. The crystal structure of the title coordination polymer, {[CoCl2(C14H14N4O2)]·0.5H2O}n, features a one‐dimensional zigzag chain, in which the cobalt ion sits at a twofold symmetry position and adopts a tetrahedral geometry, and the bridging ligand lies on an inversion center and connects to CoII ions in a bis‐monodentate mode. Furthermore, two interwoven chains create a cavity of ca 8.6 × 8.6 Å, which produces a three‐dimensional channel. Water molecules are held in the channel by hydrogen bonds. 相似文献
3.
Dominick J Lambrecht M Sanghera S Shelkov V Skwarnicki T Stroynowski R Volobouev I Wei G Zadorozhny P Artuso M Goldberg M He D Horwitz N Kennett R Mountain R Moneti GC Muheim F Mukhin Y Playfer S Rozen Y Stone S Thulasidas M Vasseur G Zhu G Bartelt J Csorna SE Egyed Z Jain V Kinoshita K Edwards KW Ogg M Britton DI Hyatt ER MacFarlane DB Patel PM Akerib DS Barish B Chadha M Chan S Cowen DF Eigen G Miller JS O'Grady C Urheim J Weinstein AJ Acosta D Athanas M Masek G Paar HP Sivertz M Gronberg J 《Physical review D: Particles and fields》1994,50(5):3027-3037
4.
Ta Chi Chiang Quang-Tho Pham Alain Guyot 《Journal of polymer science. Part A, Polymer chemistry》1977,15(9):2173-2191
Constant-composition copolymers of methyl methacrylate and vinylidene chloride produced by radical copolymerization are studied by 1H-NMR at 60 and 250 MHz. The different methods of the literature for the derivation of reactivity ratios from either the copolymer composition or the sequence average lengths, or even the diad distribution, are applied but lead to rather dispersed results. A new graphical method is proposed, based on the use of peculiar values of the triad distribution functions. It allows us to detect a penultimate effect for the vinylidene chloride-rich region. In the same range, a change in tacticity of the diads and triads on the methylmethacrylate sequences, as compared with homopolymers, is observed; it suggests that the anomaly is caused by the competition of the depropagation reaction. 相似文献
5.
In this study, Co(II), Ni(II) and Cu(II) complexes of 3-[(2,4-dinitrophenyl)hydrazono]butane-2-one oxime were synthesized
and characterized by means of IR, UV-Vis, 1H NMR spectroscopic techniques, magnetic measurements, and elemental analyses. The ligand (HL) behaves as a monoanionic bidentate
ligand coordinating via azomethine nitrogen of the hydrazone and the oxime oxygen with the displacement of a hydrogen atom
from the oxime group.
The text was submitted by the authors in English. 相似文献
6.
Frost RL Duong L Weier M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(8-9):1853-1859
A series of tungstate bearing minerals including scheelite, stolzite, ferberite, hübnerite, wolframite, russellite, tungstenian wulfenite and cuprotungstite have been analyzed by Raman microscopy. The results of the Raman spectroscopic analysis are compared with published data. These minerals are closely related and often have related paragenesis. Raman microscopy enables the selection of individual crystals of these minerals for spectroscopic analysis even though several of the minerals can be found in the same matrix because of the pargenetic relationships between the minerals. The Raman spectra are assigned according to factor group analysis and related to the structure of the minerals. These minerals have characteristically different Raman spectra. The nu1(Ag) band is observed at 909 cm(-1) and although the corresponding nu1(Bu) vibration should be inactive a minor band is observed around 894 cm(-1). The bands at 790 and 881 cm(-1) are associated with the antisymmetric and symmetric Ag modes of terminal WO2. The band at 695 cm(-1) is interpreted as an antisymmetric bridging mode associated with the tungstate chain. The nu4(Eg) band was absent for scheelite. The bands at 353 and 401 cm(-1) are assigned as either deformation modes or as r(Bg) and delta(Ag) modes of terminal WO2. The band at 462 cm(-1) has an equivalent band in the infrared at 455 cm(-1) assigned as delta(as)(Au) of the (W2O4)n chain. The band at 508 cm(-1) is assigned as nu(sym)(Bg) of the (W2O4)n chain. 相似文献
7.
James P. Kutney Peter Grice Krystyna Piotrowska Steven J. Rettig Jerzy Szykula James Trotter Loc Van Chu 《Helvetica chimica acta》1983,66(6):1820-1826
The thujone-derived enone 1 , upon base-catalyzed reaction with 2-methyl-6-vinylpyridine is converted to the pyridine analogue 5 (Scheme 1). Catalytic reduction of the latter to 6 generates two new centers of chirality which eventually become C(8) and C(14) in the ultimate synthetic steroid analogue 12 . An X-ray analysis of 6 establishes the structure and absolute configuration so as to determine its suitability in subsequent synthetic studies. The acetal derivative 7 , via Birch reduction, hydrolysis, and internal aldol cyclization, is converted into the cyclohexenone analogue 10 (Scheme 2). This ‘one-pot’ process affords an efficient conversion of the pyridine ring into a cyclohexenone system required for A-ring construction of the steroid skeleton. Finally, conversion of 10 , via the unsaturated diketone 11 , provides the chiral steroid analogue 12 . 相似文献
8.
E. M. Köksal N. Çelebi B. Ataksor A. Ulug M. Taşdelen G. Kopuz B. Akar M. T. Karabulut 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):213-216
As part of a national program to determine public exposure to natural radiation, indoor air 222Rn concentrations were determined in dwellings of Turkey. The 222Rn concentrations were measured with time-integrating passive nuclear etched track detectors in 27 provincial centers. The
indoor radon concentrations were found to be in the range of 10-380 Bq.m-3.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
The dynamic processes of N(1s) core-hole excitation in gas-phase CH3CN molecule have been studied at both Hartree-Fock and hybrid density-functional theory levels. The vibrational structure is analyzed for fully optimized core-excited states. Frank-Condon factors are obtained using the linear coupling model for various potential surfaces. It is found that the vibrational profile of the N-K absorption can be largely described by a summation of two vibrational progressions: a structure-rich profile of nu(CN) stretching mode and a large envelope of congestioned vibrational levels related to the strong (-C-CN) terminal bending bond. Excellent agreement between theoretical and experimental spectra is obtained. 相似文献
10.
The ligand has been
prepared from ω-chloroisonitrosoacetophenone and 1,4-phenylenediamine
in the presence of NaHCO3. The ligand have a C=O group
and an –NH–R group adjacent to the oxime group. The Ni(II), Cu(II)
and Co(II) complexes of the synthesized ligand were prepared and their structures
were identified using FTIR, UV-Vis spectral data, elemental analysis, thermal
analysis and magnetic moment measurements. The metal-ligand ratios were found
to be 3:2. The ligands were found to coordinate to the metal ions via the
oxime nitrogen, oxime oxygen, one of the carbonyl group and amide nitrogen
atoms. Thermal analyses data reveals that the water in the complexes was found
to be non-coordinated to the metal ions. In the trinuclear structures, the
metals have the tetrahedral environments. 相似文献