基于有机羧酸配体的Co(Ⅲ)/Cu(Ⅱ)配合物的合成、结构及表征

在溶剂热条件下,以含卤素有机羧酸3-溴-吡啶-2,6-二甲酸(H₂L)为配体,以硝酸钴、硝酸铜为金属源,合成了两例配合物:[Co(L′)₃](1)和[Cu(L′)₂]_n(2)(HL′=5-溴-吡啶-2-甲酸),通过元素分析(EA)、X射线单晶衍射(SXRD)、X射线粉末衍射(PXRD)、红外光谱(IR)和热重分析(TGA)进行结构表征。X射线单晶衍射结果表明,配体H₂L在反应过程中发生脱羧现象,生成单羧酸配体5-溴-吡啶-2-甲酸。在配合物1中,每个Co(Ⅲ)都位于略微扭曲的八面体几何构型中,不对称单元中含有两个单核单元,单核单元通过C—H…O氢键形成三维超分子结构。配合物2的不对称单元中含有一个Cu(Ⅱ),两个脱质子的L′^-配体,每个Cu(Ⅱ)都是六配位的,位于扭曲的八面体几何构型中。Cu(Ⅱ)由配体连接生成1D链结构,通过C—H…O氢键形成三维超分子结构。此外,研究了两例配合物的热稳定性能。     

Neutrino Production via e-e+ Collision at Z-Boson Peak

The production of the three normal neutrinos via e^-e⁺ collision at Z-boson peak (neutrino production in a Z-factory) is investigated thoroughly. The differences of v_e-pair production from v_μ-pair and v_τ-pair production are presented in various aspects. Namely the total cross sections, relevant differential cross sections and the forward-backward asymmetry etc. for these neutrinos are presented in terms of figures as well as numerical tables. The restriction on the room for the mixing of the three species of light neutrinos with possible externals (heavy neutral leptons and/or sterile neutrinos) from refined measurements of the invisible width of Z-boson is discussed.     

Single-step synthesis of layered double hydroxides ultrathin nanosheets

A novel single-step approach was developed to prepare large-scale MgAl-LDHs ultrathin nanosheets. The key point of the successful realization was that we employed a high concentration of H(2)O(2). Oxygen molecules, derived from in situ decomposition of H(2)O(2), were speculated to be the decisive factor leading to complete separation of LDHs layers. The ultrathin nanosheets were characterized by XRD, TEM, AFM, FT-IR, and TG-DSC. The results indicated that the thickness of these nanosheets was about 1.44 nm, which was almost in perfect agreement with the theoretical thickness of two LDHs layers. From the TG-DSC curves, the weight loss of these exfoliated MgAl-LDHs ultrathin nanosheets at 500°C was 18.5%, which was much smaller compared to the 32.3% weight loss of unexfoliated MgAl-LDHs.     

电子商务与传统商务发展趋势的博弈分析

在消费者对商品价格与供货时间的偏好假设下,建立一个厂商关于电子商务与传统商务交易方式选择的完全信息静态博弈模型,其纳什均衡表明了电子商务与传统商务潜在的发展趋势,特别是两者可能的市场剖分关系.确切而言,若市场满足既定假设,均衡条件下的电子商务交易方式表现为较长的供货时间及低于传统商务约40%的市场交易价格,将获得三分之一的市场份额.     

Solid-phase Extraction for Analysis of Short-Chain Chlorinated Paraffins in Water Samples

A method for analysis of short-chain chlorinated paraffins (SCCPs) in water based on solid-phase extraction (SPE) was established using electron capture negative chemical ionization mass spectrometry (GC-ENCI-MS). The SPE parameters, including the sorbent, eluent and elution volume were optimized. The Agilent Bond Elut-C₁₈ was precleaned with 3 mL of hexane and 3 mL of methanol, and subsequently conditioned with 3 mL H₂O prior to use. After the water samples were enriched by the cartridge, the sample was washed with 3 mL of 10% (V/V) methanol and eluted with 3 mL of hexane-dichloromethane (1:1, V/V) solution. The results indicated that the limits of detection (LOD) for SCCPs were 18 ng L^?1, while the corresponding limits of quantitation (LOQ) were 60 ng L^?1. The spiked recovery range was 90%–135%, with a relative standard deviation of less than 10%. Finally, 20 surficial water samples around Beijing were collected and SCCPs contents were analyzed using the proposed method. The SCCPs concentrations ranged from less than LOD to 682 ng L^?1 with a mean concentration of 216 ng L^?1.     

CHARACTERIZATION OF SOME SCHIFF BASES OF HETEROCYCLIC COMPOUNDS AND THEIR TRANSITION METAL COMPLEXES

Some new Schiff bases were synthesized by the condensation ofequimolar quantities of salicylaldehyde and 2-amino-5-phenylazo-pyridine orits derivatives in dry benzene(1):Metal complexes of the type ML_2and M'L_3where M=Cu~(2+),Co~(2+),Ni~(2+),Mn~(2+)Pd~(2+),M'=Fe~(3+)and L=different newly synthesizedmonobasic Schiff bases were prepared in absolute ethanolic medium(2)andcharacterized by elementary analysis,conductance measurements,infraredspectra,electronic spectra,magnetic moments studies.     

THE CRYSTAL STRUCTURE OF RARE EARTH COMPLEX WITH AMINO ACIDS Ⅱ The Crystal Structure of Gtutamate Comptex of Erbium Perchtorate

The crystat structure of {[Er_2(L—Glu)_2(H_2O)_6](ClO_4)_2·3H_2O)_2 has been studied by X-ray diffraction. The crystal is monoctinic with space group P2_1 and cell parameters a=19.987(3) , b=16.505(3) , c=11.040(2) , β=104.69(1)~o, V=3538(1) , Z=2, Dc=2.29 g. cm~(-3), μ=53.2 cm~(-1), F(000)=2384. The asymmetric unit contains two complex motecules and four centre ions. Each erbium (Ⅲ) is coordinated by five oxygen donors from four different glutamates and four oxygen donors from the aqua ligand to form a nine coordination potyhedron. The mean distances of Er—0 (carboxylate) and Er—Ow are 2.439 and 2.41 respectivety. The finat R and Rw are 0.043 and 0. 058, respectivety.     

Dimension-Controllable and Photo-Responsive Supramolecular Organic Framworks through Cucurbit[8]uril-based Self-Assembly

Dimension-controllable supramolecular organic frameworks (SOFs) with aggregation-enhanced fluorescence are hierarchically fabricated through the host-guest interactions of cucurbit[8]uril (CB[8]) and coumarin-modified tetraphenylethylene derivatives (TPEC). The three-dimensional layered SOFs could be constructed from the further stacking of two-dimensional mono-layered structures via simply regulating the self-assembly conditions including the culturing time and concentration. Upon light irradiation under the wavelength of 365 nm, the photodimerization of coumarin moieties occurred, which resulted in the transformation of the resultant TPEC\begin{document}$ _n $\end{document}/CB[8]\begin{document}$ _{4n} $\end{document} two-dimensional SOFs into robust covalently-connected 2D polymers with molecular thickness. Interestingly, the supramolecular system of TPEC\begin{document}$ _n $\end{document}/CB[8]\begin{document}$ _{4n} $\end{document} exhibited intriguing multicolor fluorescence emission from yellow to blue in the time range of 0\begin{document}$ - $\end{document}24 h at 365 nm irradiation, possessing potential applicability for photochromic fluorescence ink.     

Qualitative and quantitative analysis of Alpiniae Oxyphyllae Fructus by high-performance liquid chromatography coupled to Fourier transform-ion cyclotron resonance mass spectrometry

Alpiniae Oxyphyllae Fructus, as a homology of medicine and food, has been widely used in China for thousands of years. However, the existing qualitative and quantitative methods are difficult to evaluate the quality of Alpiniae Oxyphyllae Fructus samples from multiple sources. In this paper, an high-performance liquid chromatography fingerprint was established for assessing the quality of Alpiniae Oxyphyllae Fructus from different areas. Then, high-performance liquid chromatography was coupled to Fourier transform-ion cyclotron resonance mass spectrometry for characterization of the chemical compositions in Alpiniae Oxyphyllae Fructus. In fingerprint analysis, 54 common peaks were confirmed and six chromatographic peaks of them were identified. The similarity of 14 samples from different areas was between 0.990 and 1.000. Moreover, a total of 30 chemical components were characterized by high-performance liquid chromatography coupled to Fourier transform-ion cyclotron resonance mass spectrometry method, six compounds of which were decisively identified. Finally, the content of nootkatone was determined by high-performance liquid chromatography. In conclusion, the methods used in this study are efficient for qualitative and quantitative analysis of Alpiniae Oxyphyllae Fructus. Also, these methods can be used to control the quality of other traditional Chinese medicines.