Table of Content

10 April 2005, Volume 26 Issue 4

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Articles

Hydrothermal Synthesis and Characterization of LiNbO₃ Polycrystal Powder

YU Ji, LIU Xing-Quan

2005, 26(4):  595-598. 

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LiNbO₃ crystals were widely used in many fields because of their excellent ferric properties. In this work, LiNbO₃ powders were successfully prepared via a simple and convenient hydrothermal method with LiOH·H₂O and Nb₂O₅ as the starting materials. FTIR spectra and XRD patterns of the as-prepared samples showed good crystalline and high purity. At the same time, the effects of different Li sources, crystallization temperature and time on the as-prepared product were also investigated.

Preparation and Characterization of Patterned TiO₂ Microstructures on Silicon Surface

GUAN Fei, CHEN Miao, ZHANG Rui, LIANG Shan, XUE Qun-Ji

2005, 26(4):  599-602. 

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Micro-patterned TiO₂ films on Si wafers was fabricated by selective deposition and microcontact printing technique. X-ray photoelectron spectroscopy(XPS), scanning electron microscope(SEM) and atomic force microscopy(AFM) were used to examine the properties and microstructure of the patterned TiO₂ films. This patterned TiO₂ microstructures may be widely used in the field of photonics, optics, sensing and microelectromechanical system(MEMS).

Synthesis of Highly Ordered Large-pore Mesoporous Organosilicas by Non-aqueous Solvent Evaporation Method

ZHANG Zhen-Dong, YAN Xiao-Xia, TIAN Bo-Zhi, SHEN Shao-Dian, CHEN De-Hong, Fang Qian-Rong, ZHU Guang-Shan, QIU Shi-Lun, ZHAO Dong-Yuan

2005, 26(4):  603-606. 

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Highly ordered hexagonal mesoporous organosilicas with large pore size(>4 nm) were synthesized by non-aqueous solvent evaporation method using triblock copolymers as the structure-directing agents and 1,2-bis(triethoxysilyl)ethane as the organically bridged silica source. The mesoprous organosilicas were characterized by small-angle powder X ray diffraction(XRD), transmission electron microscopy(TEM), nitrogen adsorption, ²9 Si MAS NMR spectroscopy and scanning electron microscope(SEM).

Synthesis and Characterization of Nanosized Anatase TiO₂ Cuboids

WANG Hai, WU Yu, XU Bo-Qing

2005, 26(4):  607-310. 

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Anatase TiO₂ nanocrystals with cuboidal morphology were successfully prepared in the absence of any templates or shape-protectors by changing Ti(OH)₄ precipitate(hydrogel) into its corresponding ethanol-gels(viz., by extensive washing with absolute ethanol), followed by supercritical drying in ethanol medium and then calcination in air(named as AS preparation). The cuboidal crystals were subject to calcination at different temperatures and were characterized by N₂ physisorption, XRD, Raman spectroscopy, and TEM/HRTEM. The change of the calcination temperature in the range from 270 to 650 ℃ showed little effect on the surface area, pore volume and crystal/particle sizes of the sample. A further increase of the calcination temperature up to 800 ℃ resulted in a significant sintering of the TiO₂ nanocrystals but the sample crystal phase remained in the anatase structure. These results suggest that the as-prepared anatase TiO₂ cuboids are highly resistant to the well-known thermal effect on the phase transformation(anatase-to-rutile) of titania. However, the calcination of the sample at 1 000 ℃ resulted in a complete anatase-to-rutile phase transformation, which was companied by severe sintering growth of the TiO₂ crystals as well as a drastic change in the sample texture.

Biomemic Synthesis, Crystal Structure of Molybdenum and Tungsten Chiral Octahedral Complex(NH₃CH₂CH₂CH₂NH₂)₂[Mo_0.4W_0.6O₂(C₆H₄O₂)₂] and Its Interaction with ATP by ¹H, ¹³C,³¹P and ¹⁵N NMR

LU Xiao-Ming, DENG Yuan, LI Li, JIANG Ling, MAO Xi-An, YE Chao-Hui

2005, 26(4):  611-616. 

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A chiral octahedral molybdenum complex(NH₃CH₂CH₂CH₂NH₂)₂[Mo_<sup>0.4 W_<sup>0.6 O₂(C₆H₄O₂)₂] was obtained by the reaction of tetra-butyl ammonium β-octamolybdate with catechole and 1,3-diaminopropane in the mixed solvent of CH₃OH and CH₃CN, characterized by X-ray diffraction, and its interaction with ATP was studied by ¹H, ¹³ C, ³¹ P and ¹⁵ N NMR. The crystal is orthorhombic with space group Pcan, a=0.750 1(2) nm, b=2.399 4(7) nm, c=1.217 8(4) nm, Z=4. The central metal ion exhibits distorted octahedral coordination with cis dioxo catechole. The ¹H and ¹³ C NMR studies reveal that the central metals were reduced to M(Ⅴ) and a little catecholato ligand was hydrolyzed when the complex is dissolved in D₂O but were oxidized to M(Ⅵ) and almost part of catecholato ligands dissociated with the central metals while it is mixed with ATP in D₂O. The shift of the ¹H, ¹³ C, ³1 P and ¹⁵ N chemical shifts in adenine of ATP suggest that there is a coordinated interaction between central metal and the N atoms in adenine, and the coordination might be responsible for the anti-tumor and DNA cleavage activities of the title complex.

Synthesis of MoS₂/Carbon Composite Nanotubes

SONG Xu-Chun, ZHENG Yi-Fan, HAN Gui, YIN Hao-Yong, CAO Guang-Sheng

2005, 26(4):  617-619. 

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MoS₂/carbon composite nanotubes were fabricated by thermal decomposition of the precursor of CNTs supported with (NH₄)₂MoS₄ under H₂ atmosphere at 900 ℃. The morphologies, structure and composition of the product were thoroughly investigated by XRD, Raman spectroscopy, HRTEM coupled with EDS. The results revealed that a novel type of nanotubes composed of MoS₂ and carbon was synthesized.

Preface

Optical Properties and Synthesis of Copper Sulfide Nanorods by Solid-state Reaction at Low Heating Temperature

ZHOU Jie, JIA Dian-Zeng, LIU Lang

2005, 26(4):  620-622. 

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Well-dispersed copper acetamide sulfide nanorods were prepared by means of the solid-state reaction of copper acetate and thioacetamide in the presence of surfactant PEG-400 at a low heating temperature. The powder X-ray diffraction pattern and EDX indicated that the product was pure hexagonal phase copper sulfide nanorods. The morphology of the nanorods was characterized by transmission electron microscopy(TEM) and scanning electron microscopy(SEM). The diameter and length of CuS nanorods obtained are 80-100 nm and 200-500 nm, respectively. And the maximum peak positions of absorption spectrum and excited spectrum of CuS nanorods were observed to shift towards higher wave number compared with those of the bulk CuS. The results clearly show the fine optical properties of CuS nanorods.

Articles

Preparation of Nano-iron Nitride by Temperature-programmed Reaction from Nano-iron Oxides

ZHENG Ming-Yuan, CHENG Rui-Hua, CHEN Xiao-Wei, LI Ning, CONG Yu, WANG Xiao-Dong, ZHANG Tao

2005, 26(4):  623-627. 

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A series of nano-iron oxides with different particle sizes or bulk phases were firstly prepared from cheap inorganic iron salts by precipitation or sol-gel methods. Then, the nano-iron nitride samples were prepared from the as-synthesized nano-iron oxides by temperature-programmed reaction(TPR) method under ammonia atmosphere. The characterizations of X-ray diffraction and transmission electron microscope demonstrate that nano-iron nitride can be produced from the nano-iron oxides by TPR method. There are apparent differences in the particle sizes of iron nitride prepared from different precursors. Within some range of sizes, smaller iron oxide precursor leads to larger iron nitride particles. For the γ phase and α phase iron oxides with similar particle sizes, the former is more likely to agglomerate during the nitridation. The iron nitride particles retain the morphology of the oxide precursors.

Synthesis of Ultrafine γ-Bi₂O₃ Powder at Low Temperature

ZHENG Bo, PANG Ai-Hong, GU Jian-Sheng

2005, 26(4):  628-630. 

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In this paper, the electrochemical synthesis method was used to prepare γ-Bi₂O₃. Ultrafine Bi metal powder was first synthesized by electrochemical method at room temperature in a single cell .The anode comprised the sacrificial metal Bi; the cathode was Pt; the NaOH solution was used as the electrolyte. The ultrafine Bi metal powder had a special chemical reactivity. Then γ-Bi₂O₃ was prepared by the reaction of ultrafine Bi and NaOH solution. The effect of the concentration of NaOH solution, reaction temperature and additive were studied. The principle of the reaction was discussed. The component of the product was determined by atomic emission spectrometry and EDTA titration analysis. XRD, SEM ,TEM and DTA were employed for the characterization of the obtained products.

Synthesis, Characterization and Crystal Structure of Dimer Organotin Complex {[n-Bu₂SnO₂CCH(CS₂NEt₂)₂]₂O}₂

YIN Han-Dong, XUE Sheng-Cai, WANG Qi-Bao

2005, 26(4):  631-633. 

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The title complex {[nBu₂SnO₂CCH(CS₂NEt₂)₂]₂O}₂ was synthesized and characterized by elemental analysis, IR, NMR and Xray single crystal diffraction. The results show that the complex belongs to a monoclinic system with space group C₂/c, and unit cell dimensions: a=2.848(5) nm, {b=1.381(2) nm}, c=3.239(6) nm, β=111.11(2)°, Z=4, V=11.884(35) nm³, D-c=1.329 g/cm³, {F(000)}=4 912, S=0.991, R-1=0.053 5, wR₂=0.116 6. The complex has a centrosymmetric dimer structure mode with a fourmembered central endocyclic Sn₂O₂ unit. The endocyclic tin atoms are sixcoordination and have coordition geometry of distorted octahedron. The exocyclic tin atoms are fivecoordination and have coordination geometry of distorted trigonal bipyramid. This complex was tested in vitro against human tumour cell lines, MCF-7 and WiDr, and displayed the higher activity.

Starch Nanoparticle as Transgenic Vehicle Mediated by Ultrasound

LIU Jun, LIU Xuan-Ming, XIAO Su-Yao, TONG Chun-Yi, TANG Dong-Ying, ZHAO Li-Jian

2005, 26(4):  634-637. 

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A method in which poly-L-lysine-starch nanoparticle(PLL-StNP) could act as gene vehicle mediated by ultrasound was described in this paper. It was found that when pIRGFP plasmid DNA-PLL-StNP complexes were treated with ultrasound for different time, electrophoresis analysis showed that the biological characteristics of DNA could be well-kept, when DNA-PLL-StNP complexes were transferred into COS-7 cells mediated by ultrasound for 2 min at 120 W and 40 kHz, the cells were expressed GFP at a frequency of about 70. This method may(will) provide a wide application not only in animal transgenic technique and in human gene therapy, but also in plant transgenic technique.

Analysis of Norditerpenoid Alkaloids in Roots of Aconitum kusnezoffii by Electrospray Ionization Tandem Mass Spectrometry

XU Qing-Xuan, WANG Yong, LIU Zhi-Qiang, LIU Shu-Ying, TIAN Cheng

2005, 26(4):  638-641. 

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Electrospray ionization tandem mass spectrometry(ESI-MSn) was applied for simultaneous determination of norditerpenoid alkaloids in the roots of Aconitum kusnezoffii without any chemical isolation. The structure information of the alkaloids was gotten by electrospray ionization tandem mass spectrometry(ESI-MSn). Accordingly, four kinds of norditerpenoid alkaloids, such as monoester alkaloids, dierster alkaloids, triester alkaloids and lipo-alkaloids, were simultaneously determined in the roots of Aconitum kusnezoffii. Also, triester alkaloids and lipo-alkaloids are firstly found in the roots of Aconitum kusnezoffii.

Molecular Imprinting-{chemiluminescence} Determination of Analgin

HE Yun-Hua, LV Jiu-Ru, ZHANG Hong-Ge, DU Jian-Xiu

2005, 26(4):  642-646. 

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Chemiluminescence(CL) reaction of manganese(Ⅳ)-formaldehyde-analgin was carried out. Molecular imprinted polymer of analgin was prepared by using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The binding characteristic of the analgin-imprinted polymer was evaluated by Scatchard analysis. A new chemiluminescence method for the determination of analgin was proposed by the combination of analgin-imprinted polymer and manganese(Ⅳ)-formaldehyde-analgin CL system. The linear range is 1.0×10^-7 -1.0×10^-5 mol/L, the detection limit is 4×10^-8 mol/L, the relative standard deviation is 2.4(1.0×10^-6 mol/L analgin, n=7 ). The method was applied to the determination of analgin in human urine samples directly.

Functional Gold Nanoparticles-enhanced Electrochemical Detection of Glutathione Cross-linking Reaction and Sulfhydryl-specific Identification

LI Jin-Hua, HU Jin-Bo, LI Qi-Long

2005, 26(4):  647-650. 

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An electrochemical detection method for the cross-linking reaction and sulfhydryl-specific identification of GSH using ferrocene-capped gold nanoparticles/streptavidin conjugates was developed in this paper. Disulfide C11-NHS organic molecules were covalently immobilized on a gold electrode via {Au-S} bonds(-S-S-is reduced to-SH easily in ethyl acetate solution) and formed compact self-assembled monolayers(SAMs). Then GSH is attached to C11-NHS through the amide formation and continues to cross-link Biotin-maleimide by forming a stable thioether bond between the sulfhydryl group and double bond of the maleimide group. Finally, the ferrocene-capped functional gold nanoparticles were introduced via strong interaction effect between biotin and streptavidin. The binding events were monitored by electrochemical signal of ferrocene covering on the gold nanoparticles by voltammetry. The signal differences permit to distinguish whether there is free sulfhydryl groups in the surface-bound biomolecules. The ferrocene signal is enlarged greatly because of quantities of ferrocene moieties covering on the nanogold surface. The well-defined redox peaks attribute to that of ferrocene immobilized through the cross-linking reaction between sulfhydryl groups in GSH and maleimide groups in Biotin-maleimide. The sensitivity of this electrochemical biosensor was detected and an excellent linearity of 5 μmol/L-0.1 mmol/L for GSH concentration with the oxidation current and a detection limit of 1 mmol/L were also achieved.

Water-soluble Gold Nanoscale Network Fabricated by Host-guest Interaction and Self-assembly Method

LI Di, HUANG Yun-Jie, SUN Chun-Yan, WANG Mei-Jia, LI Jun, LI Jing-Hong

2005, 26(4):  651-653. 

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Water-soluble nanoscale network with a good stability was fabricated by cross-linking the gold nanoparticles with β-cyclodextrin and 1,8-octanedithiol inclusion complexes (ICs) through host-guest interaction and self-assembly method. Three-dimensional network with the scale of the porous range from 20 nm to 100 nm was measured by transmission electron microscopy (TEM). The fate of the ICs in the nanoscale network was examined by FT-IR. The stability of the ICs linked network was much better than that of 1,8-octanedithiol linked one, which was determined by the damping of the surface plasmon absorbance in UV-Vis spectra. This discovery is of great interest in the fields such as the nano-electronics and biological applications.

Construction of a New Method for Mobilizing the Zones of CIEF and Its Application

ZHU Gui-Jie, YANG Chun, LIU He-Chun, ZHANG Li-Hua, ZHANG Wei-Bing, ZHANG Yu-Kui

2005, 26(4):  654-656. 

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A simple method for mobilizing the focused zones of capillary isoelectric focusing(CIEF) for single-point detectors was developed, in which a linear polyacrylamide(LPA) coated capillary was connected with an uncoated capillary by an etched porous joint. The etched section allows electrical conductivity but blocks the hydrodynamic flow. The focused zones of mixed proteins was mobilized by this method successfully. Compared with the traditional gravity mobilization step, it was found that this method can mobilize the focused zones more effectively without sacrificing separation efficiency.

Determination of Quercetin in Chinese Herbal Medicine by Capillary Electrophoresis

ZHOU Xin, WANG Zi-Ming, ZHENG Jian, ZHAO Li-Wei, LIU Zhong-Ying, LI Xu-Wen, BI Shu-Yun, YAN Guo-Quan, ZHANG Han-Qi

2005, 26(4):  657-659. 

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A method for determination of quercetin in 8 kinds of Chinese herbal medicines by capillary electrophoresis(CE) with microwave assisted extraction(MAE) was developed. These medicines include Hypericum periforatum, Semen cuscuta, Flos sophorae buds, Flos sophorae flowers, Herba euphorbiae humifusae, Acanthopanax, Ginkgo biloba L. leaves and Rhododendron dauricuml. The method is simple, rapid and with satisfactory recoveries and good reproducibilities.

Improvement of Signal to Noise Ratio in MALDI-TOF MS with Addition of Salts to the Matrix

FANG Cai-Yun, ZHAI Jian-Jun, LIU Feng, YANG Peng-Yuan

2005, 26(4):  660-662. 

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CHCA as a matrix facilitates the ionization of proteins and peptides in a matrix-assisted laser desorption/ionization(MALDI) time-of-flight(TOF) mass spectrometer. The matrix itself also ionizes and so do its adducts. Matrix clusters and adducts interfere with peptide ionization and peptide mass spectrum interpretation, especially at low sample concentrations and within m/z 500-1000 range. These matrix adducts, especially within m/z 500-1000, are significantly reduced with addition of ammonium citrate, ammonium sulfate, ammonium benzoate, ammonium bicarbonate, ammonium citrate and potassium dihydrogen phosphate to the matrix and the samples were deposited onto the MALDI target. The reduction of matrix adducts improves peptide ionization and signal-to-noise ratio, which enhances the reliability of database searching.

Voltammetric and Circular Dichroism Studies on Interaction Between 1, 4-Dihydropyridine Derivatives and DNA

DU Jiang-Yan, WANG Bing-Xiang, XU Fei, CHEN Ting-Ting, SHEN Zhu-Ying, SHEN Yong-Miao, XING Wei, LU Tian-Hong

2005, 26(4):  663-666. 

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The interactions of five kinds of 1,4-dihydropyridine(1,4-DHP) derivatives with calf thymus DNA(CT-DNA) were investigated by the electrochemical method and circular dichroism(CD). The results indicated that the interaction between 1,4-DHP derivatives and CT-DNA was in the intercalative mode. The strength of the interaction increases with the decrease in the steric hindrance of 1,4-DHP derivatives. DNA double helix in solution become more loose in the presence of non-planar structure 1,4-DHP derivatives.

Synthesis of 1,8-Dihydroxy-9,10-dihydroanthracene

SHI Zheng-Wei, LI Ying, LU Guo-Yuan

2005, 26(4):  667-670. 

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Dihydroxy-9,10-dihydroanthracene has a strong potential as the intermediate in the synthesis of organic opto-electronic materials. It was synthesized from 1,8-dihydroxy-9,10-anthraquinone by the methylation, reduction(zinc/acetic acid, sodium/ethanol)and demethylation. The total yield was 37. The reduction of 1,8-dimethoxy-9,10-anthraquinone with sodium borohydride/trifluroacetic acid generated novel anthrone dimer, and its crystal structure was determined by X-ray diffraction. The crystal data indicate that anthrone dimer adopts a less overlapped transoid conformation and the two methoxyl groups and carbonyl group exist in the different sides of the dimer.

Effects of Soil Organic Matters on Adsorption-desorption Equilibria of Phenanthrene

LIANG Chong-Shan, DANG Zhi, LIU Cong-Qiang, HUANG Wei-Lin

2005, 26(4):  671-676. 

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Sorption-desoprtion to natural soil is an underlying process affecting the transport, degradation, and biological activity of hydrophobic organic contaminants(HOCs) in the environment. Mineral fractions and organic matters in soil play important roles in determining the sorption and desorption patterns of hydrophobic organic contaminants. For these contaminants, the mineral fractions of soil play minor roles than organic matter. A study was carried out to determine the relationship between organic matter content and composition of soil and the sorption-desorption of phenanthrene. Hydrogen peroxide was used to reduce the content of soil organic matter(SOM). An examination of soil sample under scanning electron microscope suggested that the pore structure of soil was slightly destroyed amd even 60 of SOM was oxidized. Elemental analysis and solid state ¹³ C NMR indicated that the proportion of alkyl C increased, but he proportion of O-alkyl C decreased with reducing the content of SOM. Phenanthrene sorption capacity and isotherm nonlinearity both decreased with increasing the degrees of SOM oxidation, supporting the viewpoint that sorption equlibrium properties of hydrophobic organic contaminants can directly related to the content of SOM. The apparent sorption-desorption hysteresis was quantified for each sample. Sorption-desorption hysteresis index varies from sample to sample, and they also appear to correlate with the chemical characteristics of SOM. The more condensed the soil organic matter is, the more geologically old the soil organic matter is, and the more apparent the sorption-desoprtion hysteresis is. We suggest that the content of SOM is a major determinant of phenanthrene sorption capacity, isotherm nonlinearity and hysteresis.

Separation and Identification of the Uremic Middle Molecules

YANG Mei, ZHANG Jian-Da, WANG Peng, LIU Xiao-Hang, YUAN Zhi, LIU Hong-Fu, YANG Hong-Tao, YANG Shu-Fen, ZHAO Jing-Li

2005, 26(4):  677-679. 

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Sera and urine from patients with severe uremia and healthy persons were separated by means of gel permeation chromatography on Sephadex G-15 column with N(C₂H₅)₃-H₂CO₃ buffer as the eluent. Two middle molecular peaks(A and B) were detected at 206 nm in normal urine, uremic serum and uremic urine, but these two peaks were hardly observed in the profile of normal sera. In contrast, the absorption at 206 nm of fractions A and B from uremic urine were smaller than that of fractions A and B from normal urine. Fractions A from normal urine, uremic serum and urine were collected and resolved into 3 subpeaks at 254 nm by high performance liquid chromatography. Two of these subpeaks, A-Ⅰ and A-Ⅱ, were detected in uremic serum, normal urine and uremic urine. The results of MALDI-TOF-MS revealed that the fraction A-Ⅰ from both uremic serum and normal urine contained a component with molecular weight 1214, which could hardly be seen in the fraction A-Ⅰ of uremic urine.

Adsorbents for Endotoxin Based on Chitosan Matrix

WANG Hui-Yan, HOU Guang-Hui, YU Mei, YUAN Zhi, LIU Bin, ZHAO Cheng-Mei

2005, 26(4):  680-682. 

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The endotoxin adsorbents were prepared by coupling divinyl amine ligands on crosslinked chitosan matrix. Their adsorption ability to endotoxin was compared. It was found that the adsorbent with polyethylene polyamine ligand had the highest adsorption capacity and its clearance percent for endotoxin in endotoxemia plasma was over 80. The results also showed that the adsorbent has good blood compatibility and clinical application foreground.

Synthesis of the Derivatives of Tetramethylpyrazine and Screening for 5-HT₃ Receptor Antagonistic Activity

JIANG Xiang-Qing, HUANG Chuan-Man, ZHU Li-Ping, YE De-Yong

2005, 26(4):  683-685. 

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According to the principle of bioisosterism and the Evans'pharmacophore model of 5-HT₃ receptor antagonists, twelve derivatives of tetramethylpyrazine were synthesized. The structures of the compounds were confirmed by MS, ¹H NMR and HRMS. All the target compounds are unreported. The preliminary activity test showed that most of the compounds had fairly potent 5-HT₃ receptor antagonistic activities, especially compound 3c. And the conformational analysis showed that the active conformation of the compounds was quite fitted to the Evans'pharmacophore model. This indicates that besides the three pharmacophoric elements, the aromatic ring and the substituents attached may affect the bioactivities of the compounds.

Synthesis, Structure and Characterization of Biphenyl-2,2'-dicarboxylic Acid-2-methyl Ester

GAO Hong-Ling, CHENG Cai, CHENG Peng, LIAO Dai-Zheng, YAN Shi-Ping, JIANG Zong-Hui

2005, 26(4):  686-688. 

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Biphenyl compounds have potential applications in coordination chemistry, bioinorganic chemistry, materials and medicine. A new biphenyl compound(biphenyl-2,2'-dicarboxylic acid-2-methyl ester) was synthesized by refluxing biphenyl-2,2'-dicarboxylic acid with Ln(ClO₄)₃·6H₂O in the mixed-solvent of methanol and water for 5 h. The crystals were characterized by X-ray single crystal diffraction, elemental analysis, IR, and ¹H NMR. It belongs to monoclinic system with space group P2₁/n and cell parameters a=1.237 7(5) nm, b=0.808 2(3) nm, c=1.404 8(6) nm, β=114.410(6)° and Z=2. The strong intermolecular hydrogen bonds observed leads to a centrosymmetric dimmer. The oxygen atoms of carboxylic groups in the title compound have strong coordination abilities. It can perhaps be employed to aggregate with transitional metal atoms or lanthanide atoms and generate new complexes, which may have potential applications in many fields. To the best of our knowledge, the synthesis, structure and characterization of biphenyl-2,2'-dicarboxylic acid-2-methyl ester were first reported.

Three Dimensional Homology Modeling of Cytochrome P450 2s1(CYP2s1) and Docking Study on CYP2s1-retinoid Acid

SUN Miao, LI Ze-Sheng, ZHANG Yuan, ZHENG Qing-Chuan, SUN Chia-Chung

2005, 26(4):  689-692. 

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By means of homology modeling and molecular dynamics simulation, the three dimensional (3D) structure of CYP2s1 was constructed on the basis of the crystal structure of CYP2c5 (PDB∶1DT6). The components and conformation of CYP2s1 binding site were proposed by using binding-site program and analyzing the binding site of the CYP family binding and catalysis characters. The ligand (retinoid acid) was docked to CYP2s1 by using the affinity program, and five conformations with lower energies were collected. By analyzing the complex of CYP2s1-retinoid acid which has the lowest energy among the five collected conformations, we know that nonbonding interaction is the major interaction in the complex, and the residues Glu 411 and Ala 414 play an important role in the binding and catalysis for this enzyme.

Time-resolved Fluorescence Spectroscopic Studies on Interaction Mechanism of Dansyl-L-serine with Bridged-bicyclodextrins

CHEN Kai, JIA Shu-Yan, HAO Ya-Qiong, WU Li-Xin, WU Yu-Qing, LIU Jun-Qiu, LIU Rui-Bin, ZHANG Jian-Ping, AI Xi-Cheng

2005, 26(4):  693-696. 

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Time-resolved fluorescence spectra were applied to study the binding of dansyl-L-serine(DLS) with β-cyclodextrin(β-CD), 2-selenium bridged β-cyclodextrin(1) and 2-tellurium bridged β-cyclodextrin(2). The differentiations of DLS in binding with three kinds of cyclodextrins were performed. The results suggest that compound 1 cannot bind with DLS efficiently. However, compound 2 can enhance the binding ability with DLS greatly in comparison with that of β-CD.

Theoretical Study on the Reaction of Ethynyl Radical with HO₂ Radical by Density Functional Theory

BAI Hong-Tao, HUANG Xu-Ri, YU Jian-Kang, LI Ji-Lai, SUN Chia-Chong

2005, 26(4):  697-701. 

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Using DFT/UB3LYP and CCSD(T) methods, the reaction ethynyl radical with HO₂ radical was studied. At UB3LYP/6-311G^** level, the geometries of stationary points(reactants, transition states, intermediates and products) were optimized, respectively, and single-point calculations are performed at the CCSD(T)/6-311G^** level by using the UB3LYP/6-311G^** optimized geometries. All the energies of the species were obtained at the CCSD(T)/6-311G^** level with inclusion of UB3LYP/6-311G^** zero-point vibrational energies(ZPVE). The calculated results suggest that the attacking of the end C atom of C₂H radical to the end O atom of HO₂ radical is the most predominant initial step for the title reaction. From intermediate 1(HCCOOH) formed in the initial step, the main product P1^CO+H₂CO can be produced, as well as the secondary important products, P2, P3, P5. The reaction heat of generating P1 is -814.40 kJ/mol. While the middle C of the ethynyl radical attacking the end O of the HO₂ radical should be the secondary, and the products P4 and P6 are obtained. By the analysis of the potential energy surface, we can draw the conclusion that all the reactions are exothermic reactions.

Preparation and Structure of Silica Membrane Supported by Hollow Fiber

LI Jian-Sheng, WANG Lian-Jun, MIAO Li-Na, HAO Yan-Xia, MIAO Xiao-YuCHENG Yue, SUN Xiu-Yun, LIU Xiao-Dong

2005, 26(4):  702-705. 

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The silica membranes supported by α-alumina hollow fibers were prepared, and their structures, appearance and pore size distribution were characterized by small X-ray diffraction(SXRD), high-resolution transmission electron microscopy(HRTEM), FTIR, SEM and nitrogen adsorption isotherm measurement. The results of SXRD and HRTEM show that the obtained membranes are partially ordered materials. SEM images indicate that the membranes supported by α-alumina hollow fibers are defect-free. Gas permeability test suggests that the membranes possess gas selectivity, and the separation factors for H₂/N₂ and CH₄/N₂ are 2.25 and 1.56 at 0.1 MPa, respectively. It is shown that the gas diffusion through the membrane is governed by Knudsen diffusion mechanism. Nitrogen adsorption isotherm measurement indicates that the most concentrative pore diameter is smaller than 3.34 nm, pore volume and specific surface area of an unsupported membrane after calcinations at 500 ℃ is 0.43 mL/g and 919.8 m²/g, respectively.

Kinetics and Mechanism of Oxidation of Glutamic Acid by Dihydroxydipriodatoargentate(Ⅲ) with Spectro-photometry in Alkaline Medium

SHAN Jin-Huan, HUO Shu-Ying, SHEN Shi-Gang, SUN Han-Wen, WANG An-Zhou

2005, 26(4):  706-709. 

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In recent years, the study of the highest oxidation state of transition metals has intrigued many researchers, which can provide new and valuable information in some fields. The kinetics of oxidation of glutamic acid by DPA in alkaline medium was studied with spectrophotometry in the temperature range of 250 ℃. The reaction was found to be pseudo-first order with respect to DPA and to be the first order to glutamic acid. At a low concentration of OH^-, the reaction rate decreased with increasing the concentration of OH^-, but when increased to an enough extent, the reaction rate increased with increasing the concentration of OH^-. The rate decreased with increasing the concentration of IO₄ and increased with the increase of μ and no free radical was detected. We bring forward the mechanism of the reaction, which can be used to explain all the experimental results. The activation parameters of the rate-determining step and the equilibrium constant were calculated at 298.2 K.

Preparation of Nanostructured Films on Surface of Pd Microelectrode Array by Square Wave Potential and Their Anomalous IR Properties

LI Jun-Tao, CHEN You-Jiang, SU Zhang-Fei, ZOU Zhi-You, CHEN Sheng-Pei, SUN Shi-Gang

2005, 26(4):  710-714. 

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An individually addressable array of Pd microelectrodes was combined with in situ microscope FTIR reflection spectroscopy in the current paper to carry out surface combinatorial studies. Pd film of different nanostructures on the array was prepared electrochemically by applying the method of square wave potential. The electrochemical behavior and surface structure of the Pd film were investigated respectively by using cyclic voltammetry and scanning electron microscopy. It revealed that, through the surface combinatorial studies, with the increase of treatment time of the square wave potential, the spectral IR characteristics of bridge bonded CO on the array was transformed successively from normal absorption band to Fano-like spectral line shape, and finally to abnormal IR features. The results demonstrate that the anomalous IR properties of Pd thin film depend strongly on the nanostructure of the film.

Electrochemical Impedance Spectroscopy of Methanol Electrooxidation on PtRu/C Catalysts

WU Gang, LI Li, XU Bo-Qing

2005, 26(4):  715-718. 

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The kinetic parameters of methanol electrooxidation on PtRu/C catalysts were investigated by electrochemistry impedance spectroscopy(EIS). The results from EIS at various potentials reveal that the cathodic polarization would contribute to enhancing methanol electrooxidation activity. The impedance behavior of methanol electrooxidation on PtRu/C catalysts at different potentials can be well explained by using the deduced kinetic theory involving one intermediate adsorbate. At low potentials, splitting of the first C-H bond of CH₃OH molecule with the first electron transfer is rate-determining step on various PtRu/C electrocatalysts, while at higher potentials, the oxidation reaction of CO_<sup>ads gradually becomes rate-determining step. The change of intermediate CO_<sup>ads-coverage and its effect on faradic current of methanol electrooxidation were also discussed according to experimental and theoretical results from EIS.

Synthesis of C₆₀ Fullerene Derivatives by Azide Alkyl Cyclo-addition and Their Optoelectronic Performance

WANG Fei, ZHOU Qing-Mei, ZHENG Li-Ping, CAO Yong

2005, 26(4):  719-722. 

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A series of imino C₆₀ fullerene derivatives was synthesized through the cycloaddition reaction between C₆₀ and a long chain alkyl azide. The electrochemical properties and UV-Vis absorption spectra of these compounds were investigated. Polymer photovoltaic cells with these imino C₆₀ fullerene derivatives as the electron acceptor and MEH-PPV as the electron donor were fabricated and their performance was studied. The solubility in organic solvents and compatibility of these derivatives with conjugated polymer electron donor phase increases with the increasing of the length and number of alkyl linked to C₆₀ fullerene core. The energy conversion efficiency(ECE) and the short circuit current(I_<sup>sc ) also increase in the same sequence. The maximum short circuit current density(I_<sup>sc ) reached 1.77 mA/cm², close to that of the device fabricated from PCBM. Extremely high photo to dark current ratio makes these devices a good candidate for sensor application.

Dynamics of Biradical Micro-reaction Between HCCO and CH(²Π)

LIU Peng-Jun, CHANG Ying-Fei, SUN Hao, SU Zhong-Min, WANG Rong-Shun

2005, 26(4):  723-726. 

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The mechanism for the biradical reaction beween HCCO and CH(^2Π) was investigated theoretically by using the DFT-UB3LYP/6-311+G^** and the high-level electron-correlation UQCISD(T)/6-311+G^** at single-point. The dual-level direct dynamics method was employed to gain the information of potential energy surface for the title reaction. The rate constants were calculated over the range of temperature 1 000-2 500 K by using variational transition-state theory. The results show that the reaction mechanism of the title reaction involves three channels, producing C₂H₂+CO product. Channels 2 and 1 are the favorable routes. It is found that the variational effect for the rate constant calculation is very small in the studied temperature range. The reaction is exothermic.

Photocatalytic Activity and Mechanism of Heterojunction Thin Films

LIN Xi, LI Dan-Zhen, WU Qing-Ping, FU Xian-Zhi, WANG Xu-Xu

2005, 26(4):  727-730. 

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The thin films of TiO₂, ZnO, Fe₂O₃ and heterojunction thin films of ZnO/TiO₂, Fe₂O₃/TiO₂ were prepared on quartz glass by dip-coating technique. The photocatalytic degradation of methylene blue on these films(λ=254 nm) showed that the photocatalytic activities of three films were in the following sequence: TiO₂>ZnO>Fe₂O₃, TiO₂/ZnO>TiO₂>TiO₂/Fe₂O₃. Compared with the films of pure ZnO and Fe₂O₃, heterojunction films of ZnO/TiO₂ and Fe₂O₃/TiO₂ had smaller contact angles, while Fe₂O₃/TiO₂ film showed super-hydrophilic property. To explain this result, a model of heterojunction band of Fe₂O₃/TiO₂, TiO₂/Fe₂O₃ and ZnO/TiO₂, TiO₂/ZnO were set up. The heterojunction band formed between the two seminconductors interface changed the transfer process of photogenerated electron-hole. Time-resolved photoconductivity spectra and Auger electron spectra results approved this explanation.

Amphiphilic HZSM-5 Zeolite Catalyst for Hydration of Cyclohexene on Phase-boundary Interface

MA Bing-Li, CHUN Yuan, ZHOU Wei, PAN Jian, XU Qin-Hua, DONG Jia-Lu

2005, 26(4):  731-736. 

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Amphiphilic HZSM-5 zeolite particles were prepared by a partial modification of the external surface of HZSM-5 zeolite with trimethylchlorosilane. These amphiphilic zeolite particles were oriented at the water-organic boundary when they were added to the mixture of cyclohexene and water or water with CCl₄. IR spectra indicated that the intensity of the band for the terminal silanols decreased significantly and the band for the methyl groups(C_H stretching vibration) emerged after modification, which gave a direct evidence that partial hydrophilic silanol groups on the surface of the zeolite were replaced by the hydrophobic alkylsilyl groups. This amphiphilic HZSM-5 zeolite exhibited a much higher catalytic activity than the parent HZSM-5 zeolite in the hydration of cyclohexene phase-boundary reaction without adding co-solvents and stirring. Because this phase-boundary reaction was proceeding through a channel-reaction mechanism, the hydrophobic HZSM-5 particles modified by trimethylchlorosilane also showed the better catalytic performance than the parent zeolite.

Specific Effect of Surfactant on the Viscosity of Dispersion System

WANG Hai-Bo, LIU De-Shan, LI Yan-Mei

2005, 26(4):  737-741. 

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A novel way for analyzing the effect of surfactant on the viscosity of dispersion system was proposed. In the proposed method the effects of the films formed by surfactant molecules on the viscosity of dispersion system was taken into account. And it was suggested that the viscosity of the dispersion system was hardly affected by micelles in the system. It was the film formed by surfactant molecules that was the important factor to affect the viscosity of the dispersion system. The states of the film changed greatly with increasing the amount of surfactant added in the system. There was a maximum value for the viscosity of the dispersion system with the changing of the film states. The film formed by ordered surfactant molecules on the interface of oil and water was beneficial to the increasing of viscosity of the dispersion system. And this kind of film was very useful to the stability of the dispersion system.

Adsorption Behavior of Poly(acrylic acid) on the Surface of Nanoparticulate Titanium Dioxide

LIUFU Sheng-Cong, XIAO Han-Ning, LI Yu-Ping

2005, 26(4):  742-746. 

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The adsorption of poly(acrylic acid) on the surface of titanium dioxide nanoparticles was investigated in aqueous suspensions. IR analysis and adsorption experimental results indicated the adsorption behavior was related to PAA mass concentration, pH value and molecular weight. Part of the PAA initially added to the suspension was adsorbed onto the particles surface after which there was a gradual attainment of adsorption plateau. The saturation amount would be higher for the higher PAA molecular weight. The quantity of adsorbed PAA decreased with increasing pH value of the suspension. The thickness of PAA adsorbed layers was calculated based on the measurements of the suspension viscosity in comparison with the viscosity of the polymer solution. It was proved that the adsorption layers thickness increased with the increase of PAA molecular weight, pH and concentration of PAA. The surface charge density and the measured ζ potential of TiO₂ particles varied distinctly after PAA adsorption. The shift of pH_<sup>iep of titanium dioxide towards lower pH value was observed in the presence of PAA. The calculated results of free energy of adsorption indicated that adsorption of PAA on the surface of titanium dioxide was a spontaneous behavior.

Theoretical Study of the Photoisomerization of 2-Methylthiophene to 3-Methylthiophene

WANG Yan-Xia, CHEN Yi-Shan, YE Song

2005, 26(4):  747-750. 

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The photoisomerization of 2-methylthiophene to 3-methylthiophene was studied at the CASSCF level with a 6-31G* basis set. The reaction channels on the ground state(S₀) and excited state(T₁) were investigated. The reaction proceeds via two diradical intermediates, one intermediate product and four transitions states on the T₁ surface. The two-diradical T₁/S₀ intersystem crossing points were located along the reaction path. It is most likely that the intersystem crossing from T₁ to S₀ occurs near the second crossing point because 3-methylthiophene can be formed very easily. Based on the computation we come to the conclusion that the intersystem crossing from T₁ to S₀ is the rate-determining step in the reaction.

Electricity Characterization of Metalloprotein at Molecular Level by Conducting Atomic Force Microscopy

ZHAO Jian-Wei, WANG Nan

2005, 26(4):  751-753. 

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The electric and dielectric properties of metalloprotein, azurin, were studied at real molecular level by using conducting atomic force microscopy(C-AFM). Under a force lower than 2 nN, dielectric breakdown was observed. When reliable electrical contact between electrodes and protein is achieved under a force greater than 5 nN, well-behaved current-voltage characters are revealed, and dependent on the force load.

Relationship Between Surface Charge Density and Surface Potential of Spherical Colloidal Particle

WANG Hao-Ping, LUO Gen-Xiang, LIU Chun-Sheng, HOU Chuang-Ye, JIN Jun

2005, 26(4):  754-756. 

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The electrical potential distribution for a charged surface in an electrolyte solution at equilibrium is described by the Poisson-Boltzmann equation. For spherical particle, it is (d²y)/(dX²)+²/X(dy)/(dX) =sinhy, where y is a normalized electrostatic potential, defined as y=eψ/(kT), and ψ is the electrostatic potential. X is a normalized distance from the sphere center with radius a. X=ka+kx=ka+ξ. In this paper a flat-plate approximation method is proposed for the resolution of the PB equation. By using the extended Langmuir's method, PB equation is changed to (d²y)/(dζ²)=1/2e^y-2/(ka)√e^y-1. Performing the integration we obtain the relationship between the surface charge density and surface potential for a spherical colloidal particle with a high surface potential. I=-(dy/dζ)_<sup>ζ=0 =e^y_0/2 +{4/(ka)}. Thus the surface excess of co-ions and the double-layer free energy are easily derived. The success of the flat-plate approximation depends so strongly on the value of surface potential y₀ and the radius of curvature of the spherical particle. When the surface potential increases even if the radius of curvature is relatively small, the flat-plate approximation is also satisfactory approximations for the sphere. It explains why the present expressions are applicable to spherical particles with a high surface potential. These expressions are shown to be satisfactory approximations to exact numerical values.

Direct Construction of Poly-L-lysine Nanostructure by Dip-pen Nanolithography

ZHOU Hua-Lan, WEI Gang, LIU Zhi-Guo, WANG Li, SONG Yong-Hai, LI Zhuang

2005, 26(4):  757-759. 

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Dip-pen nanolithography(DPN) has been developed to pattern monolayer film of various molecules in submicrometer dimensions through the controlled movement of ink-coated atomic force microscopy(AFM) tip on a desired substrate, which makes DPN a potentially powerful tool for making the functional nanoscale devices. In this letter, using direct-write dip-pen nanolithography to generate nanoscale patterns of poly-L-lysine on mica was described. Poly-L-lysine molecules can anchor themselves to the mica surface through electrostatic interaction force, so stable poly-L-lysine patterns, such as square, line, circle and cross, could be obtained on freshly cleaved mica surface. From AFM image of the patterned poly-L-lysine nanostructures on mica, we know that poly-L-lysine was flatly bound to the mica surface. These oriented patterns of poly-L-lysine on mica can provide the prospect of building functional nanodevices and offer new options for this technique in a variety of other significant biomolecules.

Preparation and Reaction Mechanism of PS/SiO₂ Composite Nanoparticles

ZENG Zhong, LIU Wen-Fang, GUO Zhao-Xia, YU Jian

2005, 26(4):  760-764. 

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A novel method, i.e., batch process was used to prepare PS/SiO₂ composite nanoparticles with both yield and binding efficiency high above 95. Compared with traditional pre-treated method, it was easy and had a good repeatability in batch process. There was little difference in average particle sizes, morphologies and dispersibility of the final composite nanoparticles obtained between two methods. The reaction mechanism of 3-methacryloxypropyltrimethoxysilane(MPTMS) in batch process was described in this report, proving that the role of MPTMS could be coupling agent, crosslinking agent or both by controlling its amount. The kinetics, which was opponent to that of some similar system reported previously, was investigated and well explained by the schematic model. The morphology and structure of composite particles were discussed as well. There are about 5-6 primary silica beads per composite particles, which formed a cluster. The core of the composite nanoparticles was made up of the cluster and PS grafted and encapsulating the cluster to form the shell.

Preparation and Sieving Property of Adsorbing Resin with Homogeneous Pore Diameter and Controllable Large Pore

ZHANG Jin-Rong, CHEN Yan-Li, ZHANG Jing-Ze, GAO Ju, SHI Rong-Fu, YANG Yi-Zhong, SHI Zuo-Qing, WANG Chun-Hong

2005, 26(4):  765-768. 

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The new type polymeric adsorbing resin with homogeneous pore diameter and sieving controllable large pore was synthesized. The method of synthesis of the resin was different from that of the normal macro porous polymeric adsorbent. By altering the initiative cross-linking degree, the pore diameter of the adsorbent could be controlled. The sieving effect of the resin was represented by separating different molecules with different sizes, such as phenol, rutin and panaxtriol Re. For the mixture of phenol and rutin and the mixture of phenol and panaxtriol Re, the ratio of wiping off phenol is 88.44 and 73.09, respectively.

Influence of Polymers on Luminesence Property of Eu(TTA)₃·2NMP

LIU Xing-Yu, GUAN Xiao-Lin, SU Zhi-Xing

2005, 26(4):  769-772. 

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The influence of three types of blending polymer including polyvinylpyrrolidone(PVP), polyvinyl alcohol(PVA) and polymethyl methacrylate(PMMA) on the luminescence property of ^Eu/thenoyl trifluoroacetone/^N-methyl -2-pyrrolidone [Eu(TTA)₃·2NMP] was studied. From the results, we found that the fluoresence intensity of ternary complex compounded with polymer was stronger than that of ternary complex, no matter that the ternary complex was either liquid or film. This paper offered the important experment foundation for membrane-forming and processing of luminescent rare earths. These systems were characterized by elementary analysis, FT-IR and fluorescent spectrometry. {Eu(TTA)}₃·2NMP keeps the coordination structure of β-diketones to Eu³⁺ , but some supramolecular interactions exist between the complex and polymers, leading to the slight change of the luminescent characteristics of the composites compared to complex.

Pseudopolyrotaxane Prepared by Supramolecular Self-assembly of Cucurbituril with Polyviologen and Its Properties

HOU Zhao-Sheng, TAN Ye-Bang, WANG Cheng-Wei, HUANG Yu-Ling, ZHOU Qi-Feng

2005, 26(4):  773-777. 

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A new kind of pseudopolyrotaxane(PPeVCB) was prepared by supramolecular self-assembly of cucurbituril(CB) with pentamethylene polyviologen(poly(N-4,4'-bipyridinium-N-pentamethylene dibromide, PPeV) in water at room temperature. The chemical structure of PPeVCB was confirmed by elemental analysis, ¹HNMR, IR and X-ray powder diffraction(XRD). The results show that CB beads are localized in the aliphatic chain and combine N+ of PPeV by non-covalent bonds; the molar ratio of CB to repeat unit of PPeV is 1∶1. The properties of pseudopolyrotaxane PPeVCB were researched by thermogravimetry analysis(TGA), UV-Vis measurements and chemical reduction. The results show that PPeVCB has a higher thermal stability, stronger absorption band and higher oxidation ability than the parent polymer.

Photoresponse Behavior of a New Photochromic Liquid Crystalline Dendrimer of the Zero Generation

ZHANG Qi-Zhen, LIU Jian-Qiang, TANG Xin-De, ZHANG Jing-Zhi

2005, 26(4):  778-781. 

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The photoresponsive behavior of a new photochromic liquid crystalline(LC) dendrimer of the zero generation(G0) in CHCl₃ and THF was described. Four 4-hexyloxyazobenzene mesogenic fragments were attached in its periphery. The intensity of light absorbed, molar extinction coefficient, maximum absorption wave length, quantum yield and activation energy were determined. The reaction rate constants of trans/cis of photochemical isomerization, photo back-isomerization and thermal back-isomerization and the equilibrium constant of photochemical back-isomerization reaction were discussed. The rate constant of the photochromic reaction of G0 is 10^-1 s^-1 , but that of photochromic LC polysiloxanes containing the azobenzene moieties is 10^-8 s^-1 , thus the photoresponsive rate of the LC dendrimer G0 is 107 times larger than that of the latter.

Free-volume, Microstructure and Solvent Diffusion Behavior of Polyolefine Based Polyurethane Studied by Positron Annihilation Lifetime Spectroscopy

YANG Yu-Run, WANG Zhi-Fen, CHEN Yong-Lin, WANG De-Ning, HU Chun-Pu, WANG Bo

2005, 26(4):  782-786. 

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A series of polyurethane(PU) films made from TDI, 1,4-BDO and hydroxyl-terminated polybutadiene(HTPB) or hydroxy-terminated polybutadiene/acrylonitrile(HTBN) was synthesized by solution polymerization. Positron annihilation lifetime(PAL) spectroscopy and DSC were applied to investigate their free volume and morphology. The free volume fraction(f_v) decreased with the increase of hard segment content. The HTBN based PUs showed smaller values of f_v, which may be attributed to its lower degree of microphase separation, while the HTPB based PUs were antithetical. Sorption experiments showed that the diffusion coefficients(D₀) of the "infinitely diluted" benzene and ethanol vapor through the PU film exhibited positive correlation with free volume fraction, but did not fit to the Fujita free-volume theory, which might be attributed to the ethanol and benzene having complicated effect of swelling.

Critical Concentration Effect During the Preparation of Self-assembled PSS/PDDA Multilayer Films

CHEN You-Fang, QIAN Jin-Wen, YANG Ping, LIN Xian-Fu

2005, 26(4):  787-789. 

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UV absorbance(A) of self-assembled films of poly(dimethyldiallyl ammonium chloride)(PDDA) and poly(styrene sulfonate)(PSS) with various concentrations of polyelectrolyte(c_P) at different concentrations of sodium chloride was investigated. It was found that the A～c_P curves display a discontinuous phenomenon. And the turning point concentration, at which the A～c_P curve starts to display a discontinuous phenomenon, is in good agreement with the critical concentration c of PSS or PDDA polyelectrolyte solutions. The results above attribute to the change of chain shape of polyelectrolytes in solutions caused by c_P and c(NaCl). Thus, it is inferred that chain shape of polyelectrolyte in solutions affects the thickness of PSS/PDDA multilayer films.

Non-viral Gene Delivery System for Glutathione-response

WANG You-Xiang, SHEN Jia-Cong

2005, 26(4):  790-792. 

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A series of cross-linking PEI were synthesized by low molecular weight PEI-{1800} and dimethyl-3,3'-dithio-bis(propionimidate) dihydrochloride(DTBP). The properties of the cross-linking PEI/DNA gene supramolecular assembly were influenced by the structure of gene support and assembly conditions, such as the N/P, pH value and salt concentration. Under the conditions of c(NaCl)=20 mmol/L, N/P=5, pH=7.4, CLPEI_<sup>50 /DNA gene assembly shows uniform spheres with particle size about 170 nm determined by AFM, better than the CLPEI_<sup>100 and CLPEI_<sup>33 as gene supports. In the presence of GSH at a concentration comparable to the intracellular environment, the -S-S-bonds of CLPEI_<sup>50 were cleavaged and the gene assembly was unpacked. Glutathione-response gene supramolecular assembly was developed via the complex of DNA and DTBP cross-linked PEI.