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991.
Two polymeric silver(I) complexes, [Ag4(TAA)2(TA)2] · 2[Ag(TA)2] (I) and [Ag2(TA)(BA)]
n
(II), where TAA is tris(2-aminoethyl)amine, TA is terephthalic acid, BA is butane-1,4-diamine, were synthesized and structurally
characterized by elemental analyses and X-ray diffraction. Complex I consists of mononuclear [Ag(TA)2] units and TA-bridged tetranuclear [Ag4(TAA)2(TA)2] units, which are further linked via Ag…Ag interactions to form chains. In complex II, the silver atoms are linked by the TA and BA groups to form chains, which are further linked via Ag…Ag interactions to form
layers. In both complexes, molecules are finally linked through intermolecular hydrogen bonds to form three-dimensional networks. 相似文献
992.
Yang Cai Zhenzhen Mo Nalaka S. Rannulu Bing Guan Srinivasan Kannupal Bruce C. Gibb Richard B. Cole 《Journal of mass spectrometry : JMS》2010,45(3):235-240
Electrospray‐generated precursor ions usually follow the ‘even‐electron rule’ and yield ‘closed shell’ fragment ions. We characterize an exception to the ‘even‐electron rule.’ In negative ion electrospray mass spectrometry (ES‐MS), 2‐(ethoxymethoxy)‐3‐hydroxyphenol (2‐hydroxyl protected pyrogallol) easily formed a deprotonated molecular ion (M‐H)? at m/z 183. Upon low‐energy collision induced decomposition (CID), the m/z 183 precursor yielded a radical ion at m/z 124 as the base peak. The radical anion at m/z 124 was still the major fragment at all tested collision energies between 0 and 50 eV (Elab). Supported by computational studies, the appearance of the radical anion at m/z 124 as the major product ion can be attributed to the combination of a low reverse activation barrier and resonance stabilization of the product ions. Furthermore, our data lead to the proposal of a novel alternative radical formation pathway in the protection group removal of pyrogallol. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
Hurth C Smith SD Nordquist AR Lenigk R Duane B Nguyen D Surve A Hopwood AJ Estes MD Yang J Cai Z Chen X Lee-Edghill JG Moran N Elliott K Tully G Zenhausern F 《Electrophoresis》2010,31(21):3510-3517
The microfluidic integration of an entire DNA analysis workflow on a fully integrated miniaturized instrument is reported using lab‐on‐a‐chip automation to perform DNA fingerprinting compatible with CODIS standard relevant to the forensic community. The instrument aims to improve the cost, duration, and ease of use to perform a “sample‐to‐profile” analysis with no need for human intervention. The present publication describes the operation of the three major components of the system: the electronic control components, the microfluidic cartridge and CE microchip, and the optical excitation/detection module. Experimental details are given to characterize the level of performance, stability, reliability, accuracy, and sensitivity of the prototype system. A typical temperature profile from a PCR amplification process and an electropherogram of a commercial size standard (GeneScan 500?, Applied Biosystems) separation are shown to assess the relevance of the instrument to forensic applications. Finally, we present a profile from an automated integrated run where lysed cells from a buccal swab were introduced in the system and no further human intervention was required to complete the analysis. 相似文献
994.
Sun HY Xiao CF Cai YC Chen Y Wei W Liu XK Lv ZL Zou Y 《Chemical & pharmaceutical bulletin》2010,58(11):1492-1496
The practical synthesis of important natural polyphenolic stilbenes, including resveratrol, piceatannol and oxyresveratrol, through Perkin methodology is described. Starting from 3,5-dihydoxyacetophenone (1), the common intermediate 3,5-dimethoxyphenylacetic acid (3) can be obtained via methylation and Willgerodt-Kindler reaction. Perkin condensations between (3) and substituted phenylaldehydes 4 furnished E-2,3-diarylacrylic acids 5, followed by decarboxylation in Cu/quinoline giving stilbene intermediates 6 which bear the Z-configuration. Finally, through a simultaneous demethylation/isomerization process in AlI?/CH?CN system, the target compounds 7a-c can be obtained respectively in good to high overall yields. The synthetic method proved to be more concise, trans-specific, mild, economical and commonly applicable. 相似文献
995.
Dual-functional materials with AIE behavior and mech-anoresponsive behavior have attracted considerable attention due to their promising applications in mechano... 相似文献
996.
Syntheses,Structural Characterization and Thermoanalysis of Transition-Metal Compounds Derived from 3,5-Dinitropyridone 总被引:1,自引:0,他引:1
Rong Fan Qiu-Ping Zhou Guo-Fang Zhang Mei-Yu Cai Ping Li Li-Hua Gan Feng-Qi Zhao Ji-Zhen Li Xue-Zhong Fan Seik Weng Ng 《Journal of chemical crystallography》2010,40(3):266-271
Abstract
Nine metal compounds of Mn(II), Zn(II) and Cd(II) derived from dinitropyridone ligands (3,5-dinitropyrid-2-one, 2HDNP; 3,5-dinitropyrid-4-one, 4HDNP and 3,5-dinitropyrid-4-one-N- hydroxide, 4HDNPO) were characterized by elemental analysis, FT-IR and partly by TG-DSC. Three of which were further structurally characterized by X-ray single-crystal diffraction analysis. The structures of the three compounds, Mn(4DNP)2(H2O)4, 4, Zn(4DNPO)2(H2O)4, 8, and Cd(4DNPO)2(H2O)4, 9, crystallize in the monoclinic space group P2(1)/n and Z = 2, with a = 8.9281(9), b = 9.1053(9), c = 10.6881(11) Å, β = 97.9840(10)° for 4; a = 8.4154(7), b = 9.9806(8), c = 10.5695(8) Å, β = 97.3500(10)° for 8; a = 8.5072(7), b = 10.2254(8), c = 10.5075(8) Å, β = 96.6500(10)° for 9. All three complexes are octahedral consisting of four equatorial water molecules, and two nitrogen or oxygen donor ligands (DNP or DNPO). The abundant hydrogen-bonding and π-π stacking interactions seem to contribute to stabilization of the crystal structures of the compounds. The TG-DTG results revealed that the complexes showed a weight loss sequence corresponding to all coordinated water molecules, nitro groups, the breaking of the pyridine rings and finally the formation of metal oxides. 相似文献997.
In this work, we investigated the fluorescence emission spectra and diffusion properties of dye molecules confined in different
positions of conical nanopore channels using a laser scanning confocal fluorescence microscope. The results showed that a
red shift of the emission spectra is observed from the tip section to the bottom section and the diffusion rate is slower
in the channel than that in bulk solution, indicating a single conical nanopore channel can be used as a convenient tool for
investigating the effect of confined space on the behaviors of molecules. 相似文献
998.
High resolution and scalable parallel algorithms for the shallow water equations on the sphere are very important for modeling the global climate. In this paper, we introduce and study some highly scalable multilevel domain decomposition methods for the fully implicit solution of the nonlinear shallow water equations discretized with a second-order well-balanced finite volume method on the cubed-sphere. With the fully implicit approach, the time step size is no longer limited by the stability condition, and with the multilevel preconditioners, good scalabilities are obtained on computers with a large number of processors. The investigation focuses on the use of semismooth inexact Newton method for the case with nonsmooth topography and the use of two- and three-level overlapping Schwarz methods with different order of discretizations for the preconditioning of the Jacobian systems. We test the proposed algorithm for several benchmark cases and show numerically that this approach converges well with smooth and nonsmooth bottom topography, and scales perfectly in terms of the strong scalability and reasonably well in terms of the weak scalability on machines with thousands and tens of thousands of processors. 相似文献
999.
We report an x-ray photoelectron spectroscopy study of the oxidation of Al(111) surfaces at room temperature, which reveals that the limiting thickness of an aluminum oxide film can be tuned by using oxygen pressure. This behavior is attributed to a strong dependence of the kinetic potential on the oxygen gas pressure. The coverage of oxygen anions on the surface of the oxide film depends on the gas pressure leading to a pressure dependence of the kinetic potential. Our results indicate that a significantly large oxygen pressure (>1 Torr) is required to develop the saturated surface coverage of oxygen ions, which results in the maximum kinetic potential and therefore the saturated limiting thickness of the oxide film. 相似文献
1000.
Cai HL Zhang W Ge JZ Zhang Y Awaga K Nakamura T Xiong RG 《Physical review letters》2011,107(14):147601
A new organic ferroelectric compound, 4-(cyanomethyl)anilinium perchlorate, proceeds a second-order phase transition from a paraelectric phase (P2(1)/m) to a ferroelectric phase (P2(1)) at 184 K. A perfect ferroelectric hysteresis loop was observed even at 10 KHz. It is the first example of a molecule-based organic ferroelectric whose polarization can be switched at such a high frequency. The temperature dependent second harmonic generation effect shows that the second-order nonlinear coefficient is nearly zero above T(c) and proportional to the spontaneous polarization below T(c), suggesting the occurrence of symmetry breaking, in good agreement with crystal structural determination. The origin of ferroelectricity was ascribed to the displacements of -NH(3)(+) cations and ClO(4)(-) anions from the symmetric positions including a small part of the order-disorder behaviors of the ClO(4)(-) anions. 相似文献