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Table of Content

    10 September 2006, Volume 27 Issue 9
    高等学校化学学报2006年第27卷第9期目次
    2006, 27(9):  0.  doi:
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    研究论文
    A Simple Method of Nano-zeolite Crystals Self-assembly and Its Application to Zeolite Membrane Synthesis by Secondary Growth
    YANG Guo-Hui1, ZHANG Xiong-Fu1*, LIU Hai-Ou2, WANG Jin-Qu1, YEUNG King-Lun3
    2006, 27(9):  1593-1598.  doi:
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    Zeolite A nano-crystals were readily self-assembled into uniform zeolite layers with high degrees of coverage on the surfaces of different substrates such as porous stainless steel(SS), ceramic and silicon wafer by a simple method mploying 3-aminopropyltriethoxysilane(AP-TMS) as linker reagent. The fabrication process involves two steps: (1) surface functionalization by immersion of the substrate into the ethanol solution with linker reagent in an autoclave at 373 K for 3 h; (2) zeolite deposition assembly by immersion of the functionalized substrate into the nano-zeolite suspension in ethanol under the same condition as above step. A continuous, intergrown, uniform zeolite membrane was obtained on the ssembled substrate by the secondary growth. The membrane pervaporation was carried out to evaluate the performance of NaA membrane for the separation of water-benzaldehyde mixture in the microreactor assembly at room temperature and 16.7 kPa vacuum pressure. It is shown that the membrane has an excellent selectivity for water. The separation factors for H2O/benzaldehyde as high as 31 033 and 11 018 were obtained for benzaldehyde feed mass fraction of 99.5% and 97.0%, respectively. Influence of three linkers including AP-TMS, 3-chloropropyltriethoxysilane(CP-TMS), and 3-mercaptopropyltriethoxysilane(SP-TMS) for the zeolite crystals assembly on the substrates was investigated. It is found that using CP-TMS as linker, only a closely packed zeolite layer can be formed on the SS, while SP-TMS as linker, a zeolite layer can not be formed on any of these substrates. The reaction mechanism of the self-assembly and role of the linker were discussed.

    Synthesis, Crystal Structure and Optical Properties of a Novel Co(Ⅱ) Complex Containing Imidazole Ligand

    JIN Feng1, MA Jian1, MA Ji-Long1, CUI Yu-Min1*, WU Jie-Ying2, TIAN Yu-Peng2,3
    2006, 27(9):  1599-1603.  doi:
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    A novel imidazole derivative with π-conjugated system, 1-[trans-4-(4-diethylaminostyryl)phenyl] imidazole(L) and its complex, CoL4(SCN)2, were prepared. The structure of the complex was determined by single crystal X-ray diffraction analysis. The crystal is of orthorhombic system, space group P1 with a=0.931 7(3) nm, b=1.275 3(4) nm, c=1.669 1(5) nm, α=89.521(5)°, β=84.591(5)°, γ=80.052(5)°, V=1.944 6(11) nm3, Z=1, μ=0.329 mm-1, Dc=1.234 Mg/m3, F(000)=765, R1=0.060 1, wR=0.138 1, GOF=1.030. In the molecular structure of Co(SCN)2L4, Co atom is six coordinated by four N atoms of the ligands(L) and two N atoms of thiocyanate to form an octahedral geometry. The untypical hydrogen bonds and π-π stacking interaction lead to three-dimensional supramolecular formation. The optical properties were experimentally studied.
    Synthesis and Characterization of Silicon Carbide Fibers by Chemical Vapor Growth
    XIE Zheng-Fang1, TAO De-Liang2, WANG Jun1, XIAO Jia-Yu1
    2006, 27(9):  1604-1607.  doi:
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    Silicon carbide(SiC) fibers were directly synthesized by chemical vapor growth(CVG). Methyltrichlorosilane(MTS) was selected as the SiC gaseous source and, ferrocence and thiophene as the catalyst and the cocatalyst, respectively. The influences of pyrolysis temperature, the contents of catalyst and the cocatalyst, and the molar ratio of H2 to MTS on the morphologies of the pyrolysis products were investigated, respectively. The products were identified by X-ray diffraction(XRD), scanning electron microscopy(SEM) coupled with energydispersive X-ray(EDX), respectively. The results show that, the products are composed of β-SiC. The growing of SiC fibers suggests a conditions-dependent process. SiC fibers with different diameters(20 nm--1.5 μm) and length(10 μm to several micrometers), therefore, can be synthesized directly by CVG under various conditions without the help of laser, high or reduced pressure.

    Synthesis and Characterization of Doped Mesoporous TiO2 Materials
    SANG Li-Xia1, MA Chong-Fang1, SUN Ji-Hong2, DAI Hong-Xing2, WANG Feng1, LI Jun1
    2006, 27(9):  1608-1611.  doi:
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    Using non-surfacatant organic compounds triethanolamine as the template, TiO2and Fe3+/V5+-TiO2 mesoporous materials were synthesized by solgel and hydrothermal method. The properties of the samples were investigated by XRD, TEM, BET and UV-Vis DRS. The XRD patterns and TEM images confirm that pure TiO2 have the wormhole-like mesoporous structure, which could be preserved by ethanol extraction and destroyed by calcination of template at 450 ℃. However, Fe3+/V5+-TiO2 removed template by calcination has the mesoporous structure, which suggests that the mesoporous structure can be steadied by the doped ion. The appropriate molar fraction of the doped ion is 0.5%. BET studies show that the N2 adsorption\|desorption isotherm plots of Fe3+/V5+-TiO2 exhibit type IV isotherms, and specific surface areas about 103.59 and 90.80 m2/g, respectively. The average pore diameter of Fe3+/V5+-TiO2 is about 10.5 and 9.6 nm, respectively. Based on the UV-Vis DRS, the gap adsorption edge in visible light region is revealed for the mesoporous Fe3+/V5+-TiO2, rather than in ultraviolet region of the commercial photocatalyst P25. It is also illuminated that the Fe or V ions are incorporated into the lattice positions of the TiO2 during the preparation.

    研究简报
    Synthesis of BaTiO3 Nanorods by Reverse Microemulsion Method
    ZHU Qi-An, SONG Fang-Ping, CHEN Wan-Ping, WANG Shu-Feng, SUN Xu-Feng, ZHANG Qi
    2006, 27(9):  1612-1614.  doi:
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    BaTiO3 nanorods were synthesized in water/OP-10/n-hexanol/cyclohexane quaternary reverse microemulsion solution at 60 ℃. The effects of the molar ratio of water to surfactant and the concentration of reactants on the diameters and lengths of BaTiO3 nanorods were studied. The products were characterized by TEM, XRD and ICP. The results show that the diameters and lengths of the prepared BaTiO3 nanorods with a cubic phase and a single crystal are approximately 15~80 nm and 300~3 900 nm, respectively. And the molar ratio of barium to titanium of products is 1.0.
    Preparation and Structural Characterization of Carboxyl-functional Ionic
    Liquidsurface-modified TiO2 Nanoparticles
    ZHANG Sheng-Mao, LI Jian, WU Zhi-Shen, ZHANG Ping-Yu, ZHANG Zhi-Jun
    2006, 27(9):  1615-1617.  doi:
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    1-Methyl-3-carboxymethyl imidazolium chlorine([C2OOHmim]Cl) ionic liquid surface\|capped TiO2 nanoparticles were prepared by using tetra-n-butyl titanate ethanol solution as a precursor. The structure of nanoparticles was characterized by FTIR, TEM, XRD and XPS. The results confirmed that [C2OOHmim]·Cl ionic liquid combined with TiO2 nanoparticles by chelation, the average diameter of TiO2 nanoparticles was about 8 nm and anatase state was obtained. And only anatase existed even after calcinated at 750 ℃. As to the formation mechanism, we think that the inorganic-organic copolymerized surface-capped layer and repulsive force of positive charge played an important role in the formation and stabilization of TiO2 nanoparticles.
    Photoluminescence Property of Meso-structure Silica Film Doped with Laser Dye by Solvent Evaporation Method
    CHEN Yue1, LI Xiao-Tian2, GULI Mi-Na2, ZHAO Lan1, ZHU Guang-Shan1, QIU Shi-Lun1
    2006, 27(9):  1618-1620.  doi:
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    A simple process were applied to the preparation of transparent meso-structure silica film which doped with laser dye at room temperatrue by solvent evaporation method. The SAXRD pattern of the film doped with Cou 151 indicates that the film retain mesopores structures. In the composite, the dye molecules were mono-disperse in the channels of meso-structure silica which was determined by blue shift in UV spectra. Redshift in the PL spectrum was observed for the composite film compared with that of dye/CHCl3 solution and this strong fluorescence can take an important action in state dye laser and in optical sensors.
    研究论文
    A Microfluidic Chip-based Flow Injection System with Gas Diffusion
    Separation and Photometric Detection
    JIA Hong-Xin1,2, WANG Shi-Li1, XU Zhang-Run1, FANG Zhao-Lun1
    2006, 27(9):  1621-1625.  doi:
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    A microfluidic chip-based flow injection system with a three-layer structure for performing gas diffusion separation was developed, using a glass substrate to fabricate the reaction channels, and PDMS to fabricate the gas-permeable membrane as well as acceptor channel-structured layers. Gas generation reaction, gas-liquid separation and analyte detection were integrated on the same chip. Samples were introduced to the microfluidic chip by using a slotted vial array nanoliter flow injection system. The system was applied to the photometric detection of ammonium ion after transformation to ammonia gas in basic medium and collection in weakly acidic acceptor stream to change the color of the bromothymol blue indicator. Sampling throughput of 60 sample/h was achieved with a sample consumption of 200 nL for each cycle. A reproducibility of 3.7% RSD(n=9) was achieved with a detection limit of 140 μmol/L NH+4(3σ). The detection limit was improved to 35 μmol/L NH+4(3σ) by increasing sample volume to 800 nL and employing a stopped flow mode for the solution.
    Comparative Analysis of Volatile Constituents in Chenpi of Different Original Plants by GC-MS and AMWFA
    YI Lun-Zhao, LIANG Yi-Zeng, ZENG Zhong-Da, WANG Ping, YUAN Da-Lin
    2006, 27(9):  1626-1630.  doi:
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    Components in volatile oils of traditional Chinese medicine are very complex. Many of them are main active ingredients. So, the two-dimensional data of volatile oils obtained by GC-MS form a very complicated analysis system with many verlapped peaks. Alternative moving window factor analysis(AMWFA) is a new method using to comparison and resolution of two-dimensional data. In this paper, GC-MS and AMWFA was combined to analyze the commonness and otherness of volatile oils in three Chenpi samples whose original plants are different. Seventy-eight of the 138 separated constituents in essential oils of Chenpi were identified and quantified by the developed method. There are 44 common components among them.
    Studies on the Difference Between Combination Reaction Enantiomeric Drugs
    with Albumins by Using a New Home-made Surface Plasomon Resonance Sensor
    ZOU Xiang-Yu, ZHOU Jian-Guang, FENG Guo-Dong, ZHANG Lei, LI Ming, JIN Qin-Han
    2006, 27(9):  1631-1634.  doi:
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    Based on surface plasmon resonance(SPR), a novel optical chemical sensor for distinguishing enantiomeric drugs was developed. The difference between combination reaction of enantiomeric drugs with albumins was studied by using this setup. According to these differences the enantiomeric drugs can be distinguished. This method was shown to have many advantages in comparison with traditional methods. The major ones include the elimination of labeling and screening rapidly.
    Electrochemical Behavior of Resveratrol and Its Interaction with DNA
    ZHENG Jian-Bin, ZHANG Hong-Fang, ZHANG Xiu-Qi, GAO Hong
    2006, 27(9):  1635-1639.  doi:
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    Electrochemical techniques were employed to study the electrochemical behavior in a wider pH range, the antioxidative ability and the interaction with DNA of resveratrol. The experimental results show that wave P1 detected in 2.0<pH<7.1 solutions was an irreversible reduction wave of resveratrol involving 2e and 2H+; and wave P3 detected in 7.3<pH<10.9 solutions was caused by the same reason with P1, wave P2 located at less negative potential was produced by the reversible reduction of ionized resveratrol involving 2e and 2H+; as expected, the reduction waves P4 and P5 of bivalent and trivalent anion of further ionized resveratrol also present in the solution with pH>11. Under the optimum conditions, a linear relationship could be established between the peak current of wave P3 and the concentration of resveratrol in the range from 8.0×10-8 to 2.0×10-6 mol/L, and the detection limit was 4×10-8 mol/L. The determination result of content of resveratrol in Chinese traditional herbal medicine Polygonum cuspidatum by the proposed differential pulse polarography method was consistent with the result by the comparison HPLC method. The antioxidative a
    bility of resveratrol and the interaction mode of resveratrol with DNA were prov
    ed by electrochemical method.

    Studies on the Stripping Regularity of Ginsenosides in Aqueous Solutions with Different pH Values by HPLC-ESI-MSn
    ZHANG-Xu1,2, SONG Feng-Rui1, LIU Zhi-Qiang1, LIU Shu-Ying1
    2006, 27(9):  1640-1644.  doi:
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    HPLC-ESI-MSn was used for the analyses of the stripping of gingsenosides in values aqueous solutions with different pH(pH=2.4~11.2). Using tandem mass spectrometry, the characteristics fragment ions of ginsenosides were obtained. The experimental results showed that the stripping of ginsenosides were different in aqueous solutions with different pH values. Acidity is a main factor for influencing the stripping of ginsenoside, and the stripping of ginsenosides are inhibitied in a high acidity(pH<4.4).
    Enrichment of Pb, Cu and Zn on Ferromanganese Oxides from Surface Coatings Collected in Natural Water

    ZHAO Xing-Min1, HUA Xiu-Yi1, FU Yao2, DONG De-Ming1, LIU Jin-Fu1

    2006, 27(9):  1645-1649.  doi:
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    Selective extraction technology was used to extract Fe oxides and Mn oxides from surface coatings. The concentrations of Fe, Mn, Pb, Cu and Zn after extracting were measured to study the enrichment of Pb, Cu and Zn on Fe oxides, Mn oxides and other components. The results show that Mn oxides contribute most to Pb enrichment and the contributions of Fe oxides and other components are relatively small. For Cu enrichment on each component, the contributions of other components are significantly higher and the contributions of Fe oxides are similar to the that of Mn oxides. The contributions of Mn oxides to Zn enrichment are higher, while the contributions of Fe oxides are close to the contributions of other components. The Pb, Cu and Zn enrichment abilities of Mn oxides are bigger than the enrichment abilities of Fe oxides. The Pb, Cu and Zn enrichment abilities of Fe oxides and Mn oxides follow this order respectively: Zn>Cu>Pb, Zn>Pb≥Cu.
    研究快报
    A Novel Optical Molecular Probe for Organophosphorus Pesticides
    YU Chun-Wei, LI Shun-Hua, XU Jin-Gou
    2006, 27(9):  1650-1652.  doi:
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    A tetranuclear cyclometalated palladium-azo complex(MOP) was synthesized according to our previous work and applied as a differential colorimetric molecular chemosensor for organophosphorus pesticides(OPPs) for the first time. This molecular probe was found to have selective recognition ability to OPPs. In a DMF-acetone mixed solvent, it showed no spectral response to oxophosphate pesticides, but exhibited differential absorption spectra in the presence of different sulfur phosphorus pesticides(SPPs). In MOP sensing solutions, concentrations of different SPPs could be detected down to a level of 10-3 g/L by spectrophotometry, which could be used for the determination of SPPs.
    研究论文
    Preparation and Characterization of β-Cyclodextrin Modified by 5-Alkyl-2-amino-1,3,4-thiadiazoles
    SUN Le, FAN Xiao-Dong, LIU Yu-Yang
    2006, 27(9):  1653-1655.  doi:
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    Five kinds of novel β-cyclodextrin derivatives modified by thiadiazole were synthesized by the reaction of 5-alkyl-2-amino-1,3,4-thiadiazole and mono-6-deoxy-6-(p-tolylsulfonyl)-β-cyclodextrin at 80 ℃ under a nitrogen atmosphere for 2 d. The method had high yields and good separation effect. The structures of the compounds were confirmed by IR, 1H NMR, 13C NMR, UV, MS and elemental analysis. In 1H NMR spectra of cyclodextrin modified by 2-amino-1,3,4-thiadiazole, it was found that the chemical shift of thiadiazole ring shifted to upfield due to diamagnetic shielding effect caused by cyclodextrin. Other spectroscopic results were also in accordance with the theoretical value. The results indicate that this method affords a general way to synthesize β-cyclodextrin derivatives modified by thiadiazole. The biological activities of compounds 1 and 2 were screened. The results show that some compounds(2d, 2e) have strong antibacterial activities.
    Synthesis of Chiral Pyrrolidinylmethanol Derivatives and Its Catalysis in the Asymmetric Addition of Diethylzinc to Aldehydes
    LIU Wen-Min, WANG Ping-An, JIANG Ru, ZHANG Sheng-Yong
    2006, 27(9):  1656-1659.  doi:
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    Chiral β-amino alcohols, using L-proline as raw material, were synthesized by esterization, protection of amino-group, Grignard reaction and catalytic hydrogenolysis. They were used as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. The effects of the amount structure of and the catalysts, solvent and reaction temperature on enantioselectivity were also studied. When the molar fraction of catalyst 5% was relative to aldehyde was used, with toluene as solvent at -10 ℃, (S)-N-benzyl-2-(di-α-naphthylhydroxymethyl)pyrrolidine(3) was successfully applied to the catalytic enantioselective addition of diethylzinc to aldehydes to give secalcohols in a good to high yields up to 82% enantiomeric excesses.
    Synthesis and in vivo Antiinflammatory Activity of Novel E-1-substituted Phenyl-3-(3'-substituted indolyl)-2-propenones
    GUO Xiao-He1,2, CHENG Sen-Xiang3, CHENG Gui-Fang4, XIE Jing-Xi3, CHANG Jun-Biao1,2
    2006, 27(9):  1660-1663.  doi:
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    A series of novel propenylone compounds 3a—3p were designed and synthesized. The title compounds were characterized by 1H NMR, IR and LC/MS. Antiinflammatory activity of compounds 3a—3i were evaluated with a in vivo model of mice ear acute inflammation edema induced by croton oil. Compounds 3d, 3f, 3g exhibited a potent antiinflammatory activity and their inhibition ratios were 19.5%, 27.6% and 16.1%, respectively.
    Design and Synthesis of Novel Chiral Imidazolium Cyclophanes and Their Enantioselective Recognition for α-Amino Acids and Their Derivatives
    GUO Sheng-Jin1,2, LUO Kui1, WANG Wen-Hai1, ZHANG Shi-Yong1, JIANG He-Yan1,
    LAN Jing-Bo1, XIE Ru-Gang1*
    2006, 27(9):  1664-1668.  doi:
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    A series of novel chiral imidazolium cyclophanes were synthesized from natural amino acids. (S)-2-(1-Imidazolyl)alkanoates(2) were prepared by cyclization and esterification. In the presence of DMAP and Et3N. Alkanoates(2) reacted with ethylenediamine to yield compounds 3 with satisfactory yields. Compounds 3 reacted with 2,6-bis(bromomethyl)-4-chlorphenol, 1,3-bis(bromomethyl)benzene or 2,6-bis(bromomethyl)pyridine to afford dibromide salts under high dilution and anhydrous condition. Finally, the hexafluorophosphates (46) were obtained by treating the corresponding dibromide salts with a saturated aqueous solution of NH4PF6. The structures of the target compounds were confirmed by IR, 1H NMR, MS, HRMS, and elemental analysis. These compounds featured large cavities and multipoint binding sites. UV spectroscopic titration experiments showed these chiral imidazolium cyclophanes exhibited good enantioselective recognition toward L- and D-amino acids and their derivatives.
    Synthesis of Novel Isoxazole Contained Glycyrrhetinic Acid Derivatives

    LIU Li-Jun2, YONG Jian-Ping2, DAI Xiao-Jun2, JIA Jiong1, WANG Xi-Zhao1, WANG Jian-Wu1

    2006, 27(9):  1669-1672.  doi:
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    In order to obtain the high anti-inflammatory, anti-ulcer and anti-viral drugs, using glycyrrhetinic acid, 11-deoxylglycyrrhetinic acid and 3-Ar-5-isoxazolemethylamine derivatives as the starting material, a series of novel isoxazole contained glycyrrhetinic acid derivatives were firstly synthesized and their chemical structures were confirmed by the methods of IR, 1H NMR, 13C NMR and MS. At the same time, the optimum conditions for the amidation of glycyrrhetinic acid were confirmed by L9(34) orthogonal experiments, that is to say: with acetonitrile as the solvent, DCC/NMM as the catalytic reagent, the orders of the adding materials were as followings: adding 0.5 mmol GTA and 0.55 mmol DCC in 8 mL acetonitrile first, stirring in cold bath for 30 min and then adding 0.55 mmol 3-Ar-5-isoxazolemethylamine and 0.55 mmol NMM in 6 mL acetonitrile, and adding these mixtures to the reaction system by syringe; reaction time was 8 h. The success of this synthetic route indicates that the optimum conditions are higly reliable. Thus a facile and effective method is provide for synthesizing the isoxazole contained glycyrrhetinic acid derivatives.
    Interaction Between Lysozyme and Three Flavones by Fluorescence Spectroscopy
    YANG Ran1, CHEN Xiao-Lan2, LI Ping1, QU Ling-Bo2
    2006, 27(9):  1673-1676.  doi:
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    The interaction between lysozyme and three flavones, including Apigenin, Luteocin and Quercetin, were studied by fluorescence spectroscopy. The influence of C3—OH and C3'—OH on the interaction of flavones-Lys were compared. The results showed that C3'—OH could enhance the binding affinity greatly; while C3—OH weakened the affinity largely. According to the structure parameters of assay flavones, the effect of hydrogen group on the flavones-protein were discussed, and the main reason resulting in the weaker binding affinity of Quercetin-Lys were explored. The results obtained from the work could supply beneficial reference for the further study of Flavone-Protein interactions.
    研究简报
    Synthesis and Characterization of 2,5-Bis(2-phenanthrenyl)-thieno[3,2-b]thiophene and Its Application in Organic Thin-film Transistors
    TIAN Hong-Kun1,2, SHI Jian-Wu1,2, YAN Dong-Hang1, WANG Li-Xiang1, GENG Yan-Hou1, WANG Fo-Song1
    2006, 27(9):  1677-1679.  doi:
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    Synthesis and characterization of 2,5-bis(2-phenanthrenyl)-thieno[3,2-b]thiophene(PhTT) were reported. The compound exhibits a great thermal stability. Absorption measurements and electrochemical characterization revealed that PhTT has a relative broad bandgap and low HOMO(the highest occupied molecular orbital) level. The field-effect mobility(μFET) of PhTT from top-contact thin film transistors was 0.021 cm2/(V·s). The thin film transistors of PhTT show a good environmental stability.
    Synthesis of N-Aroyl-N'-arylselenoureas under Phase Transfer Catalysis Conditions and Its Crystal Structure
    WEI Tai-Bao, WANG Hai, LIN Qi, ZHANG You-Ming
    2006, 27(9):  1680-1682.  doi:
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    A series of N-aroyl-N'-arylselenoureas(2a—2l) were synthesized at room temperature under phase transfer catalysis conditions by using polyethylene glycol-400 as the catalyst and the structure of compound 2a was confirmed by X-ray crystallographic analysis. In the crystal, compound 2a was assembled to a three-dimensional supramolecular structure by intermolecular hydrogen bonds. The crystal belongs to the monoclinic crystal system, P21/c space group with a=0.607 1(8) nm, b=2.605(3) nm, c=0.918 9(12) nm, β=92.43(2)°, V=1.452(3) nm3, Z=4, Dc=1.525 g/cm3; F(000)=672, μ=2.589 mm-1.
    Prediction of Saccharomyces Cerevisiae Growth Phenotypes Based on Elementary Flux Mode Analysis
    JIANG Da1, WANG Yong-Hua2, LI Yan1, ZHANG Shu-Wei1, YANG Sheng-Li2, YANG Ling2
    2006, 27(9):  1683-1685.  doi:
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    The purpose of this work is to illustrate the relationship between genotype and phenotype in the complex cellular network of saccharomyces cerevisiae. As a structureoriented method, using elementary flux mode(EFM) analysis can obtain its popularity in analysis of the robustness of the central metabolism, as well as network function of some organisms. However, this method has not been widely used for modeling gene deletion phenotype. By enumerating all the metabolic pathways, the EFM analysis presented herein can be used to identify the functional features and predict the growth phenotype of the S. cerevisiae. In comparison with the flux balance analysis(FBA), the performance of EFM analysis was superior to FBA in prediction of gene deletion phenotype. EFM analysis is demonstrated to be an effective tool for bridging the gap between metabolic network and growth phenotype.
    Light-control Asymmetric Reduction of Acetophenone by Microorganism
    WANG Meng-Liang, DU Gang, LIU Dian-Sheng
    2006, 27(9):  1686-1688.  doi:
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    Rhodobacter sphaeroide as a new biocatalysts were investigated in the asymmetric reduction of ketones to chiral alcohols. The cells were used in an aqueous system for the asymmetric reduction of acetophenone to prepare (S)-1-phenyl-ethanol by photo-electron-transfer reactions. It is found that higher product yield and product enantiomeric excess could be achieved. The results show that the enantiomer excess of the chiral alcohols was up to 99%(e.e.) and the yield is more than 90%. The effects of DCMU and the optimal reaction conditions on the reaction were investigated. The results show that the reaction was controlled by light completely, the optimal substrate concentration is 17.0 mmol/L, the optimal cell mass concentration is 0.2 g/mL, the optimal pH is 7—8, the optimal reaction time was 72 h.
    研究论文
    Studies on Molecular Recognition of Chiral Asymmetry Salen Ni to Guests Imidazole and Diamine Derivatives
    LI Xiao-Li, DUAN Ran, ZHANG Ying-Hui, RUAN Wen-Juan, ZHU Zhi-Ang
    2006, 27(9):  1689-1694.  doi:
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    By method of UV-Vis spectraophotometric titration molecular recognition behavior of novel chiral asymmetry Salen Ni complexes(Host 1 and Host 2) with imidazoles and diamines in CHCl3 were studied. The results showed that the association constants decreased in the orders of Kθ(ethane-1,2-diamine)>Kθ(propane-1,2-diamine)(diamine derivatives) and Kθ(Im)>Kθ(N-MeIm)>Kθ(2-MeIm)>Kθ(2-Et-4-MeIm)(imidazole derivatives). When Salen Ni(host 1) reacts with 2-Et-4-MeIm, the coordination number is 1. In other systems the coordination number is 2. The thermodynamic functions ΔrHθm, ΔrSθm were also measured. The results indicated the processes were exothermic and entropy decreasing. The CD spectra of host-guest system was studied and the results were consistent with those of thermodynamics. Moreover, the lowest energy configurations of host-guest system were obtained by simulated annealing, and quantum chemical calculation was performed based on the configuration to explain the experimental results.
    Theoretical Study of Reaction Mechanism of Silicon Single Crystal Epitaxial Growth in SiHCl3-H2 Gas Phase
    SUN Ren-An1,2, ZHANG Xu3, HAN Ke-Li4
    2006, 27(9):  1695-1698.  doi:
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    According to the experimental condition, we projected three possible paths a, b, c of the reaction between SiHCl3 and H2 and path d of SiHCl3 decomposition in gas phase. The substrate silicon-participating reactions that include SiHCl3-H2-Si, SiHCl3-H2-Si2, SiHCl3-H2-Si9-H12 were also discussed and the substrate silicon is simulated by using clusters of Si, Si2, Si9H12 respectively. The geometries, vibrational frequencies and energies of every stable point of the system were calculated by using Gaussian 98 program at B3LYP/6-311G* level. It is shown that the decomposition paths d and c of the reaction between SiHCl3 and H2 can be considered as the competing reaction in gas phase, but silicon atoms were not formed. So we consider that single crystalline silicon can deposit on the substrate silicon only under the condition of reaction between SiHCl3-H2 and the substrate silicon.
    EQCM Study of Effect of Allyl Thiourea on Anodic Dissolution and Cathodic Deposition of Cu in Acidic Media
    CHEN Guo-Liang1,2, ZHOU Jian-Zhang1, LIN Zhong-Hua1, LU Jiang-Hong2, LIN Jin-Mei2
    2006, 27(9):  1699-1702.  doi:
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    The anodic dissolution and cathodic deposition of Cu and effect of allyl thiourea on the processes in acidic media were investigated by using cyclic voltammetry and EQCM. The experimental results demonstrated that there is only one current peak in the anodic dissolution and cathodic deposition of Cu, the M/n value of which is 32.0 and 34.2 g/mol, respectively, showing that the anodic dissolution and cathodic deposition of Cu correspond to the two-electron processes. No Cu+ ions, adsorbed Cu(Ⅰ) species or intermediate Cu+ was evidenced by in situ EQCM measurements, allyl thiourea may change the mechanism of the anodic dissolution and cathodic deposition of Cu. The M/n values of the anodic dissolution and cathodic deposition of Cu in the presence of allyl thiourea are 61.9 and 65.4 g/mol, respectively, indicating the one-electron processes and producing Cu(Ⅰ) species. The mechanism of the anodic dissolution and cathodic deposition of Cu can be considered as: AT(solution)=AT(suface); Cu=Cu+(solution)+e; Cu++AT=(CuAT)+(solution). The EQCM studies provided quantitative results of surface mass changes during cathodic deposition and anodic dissolution of Cu, and threw a new light in the elucidating electrodeposition and anodic dissolution of Cu.

    Quantum Chemistry Calculation on Structures and NLO Cofficients of H3PAuR Type Mononucleus Au(Ⅰ) Complex
    QIU Yong-Qing1, MOU Li2, SU Zhong-Min1, SUN Shi-Ling1, QIN Chun-Sheng1, WANG Rong-Shun1
    2006, 27(9):  1703-1707.  doi:
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    Different quantum chemical ab initio methods and basis sets were adopted to investigate the structures and second-order nonlinear optical properties of H3PAuR type mononuclear Au(Ⅰ) complexes. The influence of different calculation methods and basis sets of Au on the calculation results were also discussed systematically. The results indicate that different methods give rise to a great effect on the structures and secondorder nonlinear optical properties of mononuclear Au(Ⅰ) complexes. Herein, the length of coordinative bond of Au—P from HF method is shorter than that from DFT B3LYP and MP2 methods. Moreover, the second-order NLO coefficients obtained by DFT B3LYP and MP2 methods are two times larger than that by HF method. Based on the same methods, the coordinative bond length of Au—P decreased with increasing the number of d orbitals in the basis set of Au. Meanwhile, with increasing the basis sets of Au, the energy gap of frontier molecular orbitals decreased, which can be observed clearly for the SDD and CEP-121G basis sets. However, different basis sets have little influence on the second-order NLO coefficients. The difference of βμ value with different basis sets of Au for most of the molecules is less than 10%.

    Template Preparation and Magnetic Properties of Cobalt Nanowires
    WEN Ge-Hui, REN Fang-Xing, DENG Yong-Feng, ZHAO Qiang, ZOU Guang-Tian
    2006, 27(9):  1708-1710.  doi:
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    Porous anodic aluminium oxide(AAO) template was fabricated by two-step anodization. Cobalt nanowires were formed in the pores of AAO template by using dc electrochemical deposition. The structure and magnetic properties of the sample were studied by scanning electron microscopy(SEM), X-ray diffraction(XRD) and vibrating sample magnetometer(VSM). The results show that the pores of the template were straight and had nearly the same diameter. Cobalt nanowires are hcp polycrystal. The cobalt nanowires show a clear magnetic anisotropy. This is mainly due to shape anisotropy.

    Potential Controlled Self-assembly of ZnO-surfactant Hybrid Multilayers on Solid-liquid Interface
    JING Huai-Yu, LI Ming, MAI Zhen-Hong
    2006, 27(9):  1711-1715.  doi:
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    We synthesized highly oriented zinc oxide-surfactant multilayers on silicon substrates from Zn(NO3)2 solutions containing extremely low concentration of sodium dodecyl sulfate. The structure of the multilayers was investigated by X-ray photoelectron spectrum, X-ray technologies and scan electron microscopy. Two methods were used to control the electrode potential. The results show that in the multi-potential step deposition mode one can change the period of the lamellar structure only when the concentration of the surfactant is below the saturated concentration at the corresponding potential. In the potentiostatic deposition mode, the films exhibit well-defined and homogeneous lamellar structure only at low potential. All the results indicate that the assembly of the surfactant molecules and metal ions on the solid-liquid interface is determined by the electrode potential, which controls the relative speed of the reduction of the zinc ions and the aggregation of the surfactant.
    Synthesis and Characterization of Puerarin Derivatives and the Mechanism of Derivation Reaction
    HAN Rui-Min1, TIAN Yu-Xi1, WANG Peng1, XIANG Jun-Feng2, AI Xi-Cheng1, ZHANG Jian-Ping1
    2006, 27(9):  1716-1720.  doi:
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    7,4'-Dipropyl(Ⅰ), 7-propyl(Ⅱ) and 4'-propyl(Ⅲ) derivatives of puerarin were synthesized and characterized by using 1H NMR, NOESY and HRMS. Among the derivatives, Ⅱ is a new-type substituted compound of puerarin. 1H NMR spectroscopic analysis of aromatic protons combined with theoretical analysis of molecular structures proved the existence of two rotational isomers at 300 K, as well as a rapid interconversion equilibrium at 330 K for both compounds Ⅰ and Ⅱ. However, only one conformer exists for compound Ⅲ and puerarin containing 7-phenolic hydroxyl instead of propyl in A-ring as the case of compounds Ⅰ and Ⅱ. Based on UV-Visible absorption data of neutral and basic solutions, and on the density function calculations, the 7-phenolic hydroxyl group in A-ring was found to be more acidic than the 4'-phenolic hydroxyl group in B-ring. The mechanism of derivation reaction and the structure-reactivity relationship of puerarin as an antioxidant were further discussed.
    Effect of Synthesis Media on Fluorescence Intensity of Organic Complex of Rare Earth Terbium and o-Phchalic Acid
    CUI Dan1, CAI Wei-Min1, JIANG Kun2, ZHANG Ming-Yan3, CHEN Ye2
    2006, 27(9):  1721-1724.  doi:
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    A series of rare earth complexes were synthesized by changing reaction medium(methanol, ethanol, n-propanol and n-butanol sequentially) for the first time, with Tb3+ as the central ion, o-phthalic acid as the ligand. Coordination condition, probable coordination structure and composition of the rare earth complexes were determined by elemental analysis, IR spectra and UV absorption. Fluorescence spectra were determined also. The results showed that fluorescence intensity of the complexes was reduced with the sequence of methanol, ethanol, n-propanol and n-butanol. This may be due to the space effect of the solvent. Magnetic property was measured at 2—300 K and the complex belongs to the antiferromagnetic.
    Synthesis Property Characterization of Coreshell Co@SiO2 Magnetic Nanoparticle and Its Biomedical Applications to Cell Separation and Cell Chip
    GUO Xiao-Ying1, WANG Yong-Ning2, GU Lin-Gang3, HE Yan-Feng4, ZHANG Chun-Xiu1, TANG Zu-Ming1, LU Zu-Hong1
    2006, 27(9):  1725-1728.  doi:
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    In this paper, Co@SiO2 nanoparticles with the apparent coreshell magnetic nanostructure were synthesized by reducing and hydrolysis in aqueous solutions. The TEM, VSM, SEM, and the confocal fluorescence microscope were utilized to characterize the morphology, size, magnetism of the Co@SiO2 nanoparticles, and the coreshell materials were applied to the cell separation, immunophenotyping of leukemias and lymphomas diagnostics chip, in which strenuous procedures were omitted by the use of the magnetic coreshell nanoparticles, and separation. These core-shell nanoparticles were proved to have obvious cores and shell, and the cores have strong magnetism, and the shell protected these nanosized metal particles from coagulation due to anistropic dipolar attraction and oxidation very well. However this method could not limited the original cores below the size of 10 nm, which is the critical size of superparamagnetisizm, as a result coagulation due to remanent magnetism limited this core-shell particles from further applications in bioseparation.
    XPS Study on Adsorptive Desulfurization of Thiophene over Rapidly Quenched Skeletal Ni
    XIE Fu-Zhong1, HU Hua-Rong1, QIAO Ming-Hua1, YAN Shi-Run1, FAN Kang-Nian1, LEI Hao2, TAN Da-Li2, BAO Xin-He2, ZONG Bao-Ning3, ZHANG Xiao-Xin3
    2006, 27(9):  1729-1732.  doi:
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    The adsorptive desulfurization of thiophene on rapidly quenched skeletal Ni(RQ Ni) was investigated by XPS. At 298 K, thiophene in direct contact with RQ Ni undergoes C—S bond scission, forming metallocycle-like species and atomic sulfur on metallic nickel. Further exposure to thiophene leads to physisorbed thiophene. At 373 K, most of the physisorbed thiophene desorbs, with a small portion undergoing sulfur abstraction on the newly exposed nickel surface. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species at higher temperatures, which has been considered to be the dominant reaction pathway on Ni single crystals. At 473 K, the C1s peak disappears, leaving nickel sulfide on the surface.
    Micro-dynamics of Hydrogen Abstraction Reaction Between CH4-nFn(n=1—3) and CH3
    FENG Li-Xia1, WANG Wen-Liang1, LI Lin1, WANG Wei-Na1, LUO Qiong1,2, LI Qian-Shu1,2
    2006, 27(9):  1733-1737.  doi:
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    QCISD(T)/6-311+G(d,p)//BHandHLYP/6-311G(d,p) method was employed to reveal the reaction mechanism and to predict the micro-kinetic character of the hydrogen abstraction reactions of H4-nFn(n=1~3) with CH3. The rate constants of the reactions were evaluated by means of the canonical variational transition-state theory(CVT) conjunction with small-curvature tunneling(SCT) correction in the temperature range of 200—3 000 K. In this study, the reaction energies ΔE of R1a, R2a and R3 are -12.7, -9.5 and 11.8 kJ/mol, the potential barriers ΔEwere 67.0, 62.2 and 67.5 kJ/mol, respectively. At 437 K, the CVT/SCT rate constants were 6.72×10-19, 8.01×10-18 and 8.82×10-20 cm3/(molecule·s), which were in agreement with the experimental values 3.31×10-19, 1.05×10-18 and 8.33×10-20 cm3/(molecule·s). The results indicate that the tunneling effect was considerable at the lower temperatures, while the variational effect was almost negligible in the entire process.
    Effects of LiCF3SO3 Dioxolane-based Electrolytes on the Electrochemical Properties of the Sulfur Cathode for Rechargeable Li/S Batteries
    YUAN Ke-Guo, WANG An-Bang, YU Zhong-Bao, WANG Wei-Kun, YANG Yu-Sheng
    2006, 27(9):  1738-1741.  doi:
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    In order to study the effects of electrolytes on the electrochemical properties of sulfur cathode for rechargeable lithium sulfur batteries, viscosities, ionic conductivities and sulfur solubilities of binary and multiple solvent 1 mol/L LiCF3SO3 electrolytes based on 1,3-dioxolane(DOL) were measured. The results from cyclic voltammograms and various discharge profiles indicated that the electrolyte with the lower viscosity and the higher donor number could favor to improve the redox reaction activity and reversibility of the sulfur cathode, and correspondingly to improve the low discharge voltage plateau and the discharge rate. Furthermore, an electrolyte with the lower viscosity preferred to improve the surface layer microstructure of the sulfur electrode, to increase the ionic diffusion rate of electroactive species and to decrease the charge transfer resistance. At the charge/discharge current density of 0.1/0.2 mA/cm2, sulfur cathode achieved an initial discharge specific capacity of 792 mA·h/g and the specific capacity of 412 mA·h/g of the 29th discharge.
    Electrocatalytic Properties of Nano-crystalline Tungsten Carbide Thin Film Electrode for Nitromethane Electroreduction
    ZHENG Hua-Jun, GU Zheng-Hai, ZHAO Feng-Ming, HUANG Jian-Guo, WANG Wei, MA Chun-An
    2006, 27(9):  1742-1745.  doi:
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    The nano-crystalline tungsten carbide thin film was deposited on Ni substrate by magnetron sputtering physical vapor deposition. The morphology and crystal structure of the thin films were characterized by SEM and XRD. The results show that these thin films have nano-crystalline structure, the size of the uniformly grains ranges between 20—35 nm. The main components of the thin film were WC1-x. Electrocatalytic properties and reaction mechanism of nitromethane electroreduction on nano-crystalline tungsten carbide thin film electrode were investigated by electrochemical methods. The experiment result indicates that these electrodes showed a good electro-catalytic activity. Current peak of 14.9 mA/cm2 of nitromethane electroreduction appeared at -0.89 V(vs. SCE) and the reaction activation energy was 12.3 kJ/mol. The electrocatalytic reduction of nitromethane on these electrodes was a one-step reaction, and the reactions was irreversible. The control step of nitromethane eleroreduction on WC thin film electrode was electron exchange process.
    研究简报
    Effect of Pt on Co3O4 Reduction via Electrical Conductance Method
    XU Dong-Yan, DUAN Hong-Min, LI Wen-Zhao, GE Qing-Jie, YU Chun-Ying, XU Heng-Yong
    2006, 27(9):  1746-1748.  doi:
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    The reduction features of Co3O4 and Pt/Co3O4 were studied by electrical conductivity in this paper. Combined with the TPR results, it is concluded that the presence of noble metal Pt could significantly decrease the reduction temperature of Co3O4. In addition, the electrical conductance ratios of Co3O4 and Pt/Co3O4 under different atmospheres, which are in a consecutively changing sequence of hydrogen, oxygen and syngas, were also investigated. It is found that the cobalt oxides resulted from the oxidation of Co metal under oxygen atmosphere can be re-reduced by the syngas in the presence of Pt noble metal. Because the electrical conductance study was conducted at 493 K, which is close to the typical reaction temperature of FischerTropsch synthesis with cobalt based catalysts. It is reasonably speculated that the presence of Pt is beneficial to inhibiting the oxidation of cobalt metal during the Fischer-Tropsch synthesis, and thus eliminating the deactivation of cobalt catalyst.
    Preparation and Performance of Na2Ta2O6 Photocatalyst
    SUN Chao, HUANG Lang-Huan, LIU Ying-Liang
    2006, 27(9):  1749-1751.  doi:
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    Na2Ta2O6 photocatalyst was prepared by a combination of solid-state reaction with hydrothermal approach. The samples were characterized by XRD, SEM, FT IR, DRS and BET. Powder X-ray diffraction data revealed that it had well crystallized, belongs to cubic structure and pure phase. SEM images showed that the photocatalyst were clava with floccule in the middle of it. The band gap of Na2Ta2O6 was estimated to be 4.6 eV from the UV-Vis diffuse reflectance spectra. Under UV-light irradiation, it showed a photocatalytic activity for degradation of Congo Red solution.

    Dilution Enthalpies of Formamide in Aqueous Ethylene Glycol Solutions
    WANG Xu, XU Li, ZHANG Rui, LIN Rui-Sen
    2006, 27(9):  1752-1754.  doi:
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    The dilution enthalpies of formamide in aqueous ethylene glycol solutions were determined by using a CSC-4400 isothermal calorimeter at 298.15 K. The homogeneous enthalpic interaction coefficients in the range of ethylene glycol mass fraction(0%—40%) were calculated according to the excess enthalpy concept. The results show that enthalpic pair interaction coefficients h2 of formamide are negative in aqueous ethylene glycol solutions and pass through a minimum at w≈0.20 of ethylene glycol in mixed solvents.
    研究论文
    A Rheological Study on Wall Slip of Polymer Melts
    LIAO Hua-Yong, FAN Yu-Run
    2006, 27(9):  1755-1761.  doi:
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    Wall slip of the melts of polydimethylsiloxane(PDMS), polymethylvinylsiloxane(PMVS), high-density polyethylene(HDPE) and polypropylene(iPP) were studied experimentally by using a rotational rheometer with parallel plate fixtures and checking the gap dependence of the stress/strain data. In the steady shearing flow it was found that, contrast to HDPE, there seems to be no critical shear stress for the onset of slip of PMVS. In the dynamic oscillatory shear flow, as the strain amplitude increasing, the stress data obtained at different gaps first overlapped well in the linear and the early part of nonlinear regions, then, at a certain strain amplitude, started to diverge, indicating that wall slip or strain stratification occurred. Employing the elastic/viscous stress-decomposition technique proposed by Cho et al.'s, we have examined possible candidates among various parameters that could be used to determine the onset of wall slip. The dimensionless parameter τ'max/|G*|, i.e., the ratio of the maximum elastic stress in a cycle to the linear complex modulus, was found to vary in the range from 0.26 to 0.49 for the four kinds of polymer melts when the wall slip or strain stratification occurred. In that range, the onset value decreases weakly as the angular frequency increases and is almost independent of the temperature in considerable large ranges. Thus elastic stress is the key factor causing the wall slip or strain stratification of polymer melts, which supports the conclusion of Vinogradov and Insarova′s earlier investigation.

    Generalization of in-|situ Polymerization New Method for Preparing Core-shell Polymeric Nanospheres and Hollow Spheres
    ZHANG You-Wei1,2, ZHAO Jiong-Xin2, JIANG Ming1, WANG Jia-Ye2
    2006, 27(9):  1762-1766.  doi:
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    According to the new method for preparing core-shell nanospheres developed in our group, using two monomers of 2-hydroxypropyl methacrylate(HPMA) and vinyl acetate(VAc), two kinds of core-shell nanospheres with poly(ε-caprolactone)(PCL) as the core and crosslinked PHPMA or PVAc as the shell were successfully prepared under the similar conditions. After degrading the PCL cores of the obtained two nanospheres by lipase, the corresponding cross-linked poly(methyl acrylic acid) hollow spheres and cross-linked poly-(vinyl alcohol) hollow spheres were obtained. The results indicate that the new method which we proposed for preparing core-shell polymeric nanospheres via in-situ polymerization can be generalized to a certain extent, and it is suitable for the system in which the monomer is soluble in the water while its corresponding polymer is insoluble in the water.
    Synthesis and Liquid Crystalline Behaviour of Benzoic Acid Derivatives Containing Methoxyazobenzene
    BAI Bing-Lian, LI Min
    2006, 27(9):  1767-1770.  doi:
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    A novel type of H-bonded liquid crystals, namely 3,4,5-{4-[(4-methoxy-phenyl)-azo]-phen-oxy}-alkoxy-benzoic acid(Dn, n=3,6,10), was synthesized and characterized. The FT IR spectra of D10 in the range of 1670—1650 cm-1 at different temperatures were examined. The results show that the carboxyl acid groups in D10 are associated to form intermolecular double hydrogen bonding between —C=O and —OH groups in crystalline up to the isotropic phase. The benzoic acid derivatives exhibiting nematic phase were obtained through molecular design by preventing segregation and modulating intermolecular interactions effectively.
    Self-assembly of Amphiphilic Linear-hyperbranched Multi-arm Copolymer into Cationic Vesicles
    TIAN Hua-Yu, XIA Jia-Liang, LIN Hao, CHEN Lei, CHEN Xue-Si, LI Yue-Sheng, JING Xia-Bin
    2006, 27(9):  1771-1774.  doi:
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    Amphiphilic linear-hyperbranched multi-arm copolymer poly(ethylene glycol)-polyethylenimine-poly(γ-benzyl L-glutamate)(PEG-PEI-PBLG) can self-assemble into cationic vesicles in aqueous solution. TEM, DLS, SLS and zeta potential measurement were used to characterize the structure of the PEG-PEI-PBLG vesicles. The vesicles were constituted of 5—10 nm bimolecular layers with average diameter in 100 nm and surface zeta potential of +25.2 mV. The positive charges on vesicles surface were caused by the protonation of PEI in aqueous solution. The cationic vesicles have an ability to carry negatively charged proteins.

    Phenylethynyl End-capped Polyimide Oligomers Derived from BTDA
    RAO Xian-Hua, DANG Guo-Dong, ZHOU Hong-Wei, DENG Yong-Qiang, LU Ying-Bin, CHEN Chun-Hai, WU Zhong-Wen
    2006, 27(9):  1775-1778.  doi:
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    A diamine monomer[2,5-bis(4-aminophenoxy)biphenyl(p-TPEQ)] was synthesized by four-step routes, and 4-(1-phenyl ethynyl)-1,8-naphthalic anhydride(PENA) was synthesized and characterized as well. Two series of phenylethynyl\|terminated imide oligomers were prepared by reacting BTDA with p-TPEQ, and end-capped with 4-phenylethynylphthalic anhydride(PEPA) or P
    ENA. The thermal curing processes of the oligomers were investigated by FTIR, differential scanning calorimetry. As a result of undergoing a complex reaction of the phenylethynyl in the heating run, Tg increased with the increase of content of
    phenylethynyl. The obtained imide oligomers were molded into films. The cured
    films exhibited excellent mechanical properties and thermo-oxidative stability. All the results indicate that the incorporation of p-TPEQ monomer can increase the solubility and processing ability of the oligomers.

    研究简报

    Van der Waals Condensed Behavior of Polymer Fluids

    QIAO Bao-Fu, ZHAO De-Lu
    2006, 27(9):  1779-1781.  doi:
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    The condensed behavior of polymer fluids were studied based on the van der Waals interaction. By comparing the phase diagram of pure polymer fluids and that of van der Waals non-ideal fluids, it is found that (1) pure polymer fluids show a similar phase diagram to van der Waals non-ideal fluids; (2) the differences between the phase diagrams were caused by the difference of chain lengths. It is explained that why the vapor pressure of polymer is hard to detect and why the negative pressure can exist in polymer liquids. It is also found that some scaling relations exist between the reduced critical pressure and the chain length, and the reduced critical volume and the chain length.
    Studies on Unstable Structures in Urea\-ormaldehyde Resins Prepared in Strong Acid Medium
    LI Ai-Ping, KAN Cheng-You, DU Yi, LIU De-Shan
    2006, 27(9):  1782-1784.  doi:
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    The variations of unstable structures in the synthesized urea-formaldehyde (UF) resin systems with the change of the molar ratios of formaldehyde to urea were discussed by 13C NMR spectroscopy. The results show that the relative contents of dimethylene ether groups, methylols and unreactive formaldehyde increased gradually with the increase of the molar ratios of formaldehyde to urea from 0.5 to 3.0, which implied that the structure of UF resins can be optimized by controlling the molar ratios of formaldehyde to urea in the process of synthesizing UF resin. It is optimal for the molar ratios of formaldehyde to urea in the range of 1.5 to 2.0, as evidenced by small amounts of unstable structures and significant amounts of stable structures in UF resins prepared.
    Preparation and Characterization of ZnS∶Mn/PVA Composite Nanofibers via Electrospinning
    WANG Hai-Ying, YANG Yang, LU Xiao-Feng, WANG Ce
    2006, 27(9):  1785-1787.  doi:
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    ZnS∶Mn/poly(vinyl alcohol)(PVA) composite nanofibers were successfully prepared by using electrospinning technique and gas-solid reaction. The composites were characterized by means of TEM, SEM, FTIR, XRD, UV, PL measurements. The results indicate that the Mn\|doped ZnS nanocrystals with diameter about 3 nm were well-dispersed in PVA nanofibers through the coordination between —OH and Zn2+∶Mn, which prevented the ZnS∶Mn nanoparticles from aggregating in the nanofibers. Furthermore, the PL measurement demonstrates that the luminescence properties of Mn-doped samples changed significantly compared with the un-doped sample, which was caused by the influence of Mn centers.
    Influences of Intramolecular Cyclization on PVA Crosslinked System
    ZHAO Da-Cheng, GAO Ge, LI Zhi-Ying, LIU Feng-Qi
    2006, 27(9):  1788-1790.  doi:
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    The influences of intramolecular cyclization on the crosslinking reaction processes and the gel's swelling ratio in polyvinyl alcohol (PVA)-glutaraldehyde(GA) system were studied. The results show that the intramolecular cyclization is a very important factor that has influence on the formation of PVA networks. The lower PVA concentration, the higher intramolecular cyclization degree and higher critical gelation mixing molecular molar ratio of CHO to OH(rc) were obtained. The intramolecular cyclization fractions were increased with the decrease of PVA concentration. Equilibrium swelling ratio decreased with the increase of PVA concentration at the same extent of reaction and the increase of crosslinker concentration at the same PVA concentration. The formation of network can be adjusted with the change of the PVA concentration or the crosslinker concentration.