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Synthesis and surface properties
of polyurethane modified by polysiloxane
BAI Chenyan, FENG Linlin, ZHANG Xingyuan, DAI Jiabing, GE Zhen, CHAO Jing
Front. Chem. China. 2008, 3 (1): 1-5.
https://doi.org/10.1007/s11458-008-0001-8
A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50°C. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.
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Kinetic analysis of interaction
between lipopolysaccharide and biomolecules
YANG Fan, YANG Xiurong
Front. Chem. China. 2008, 3 (1): 14-17.
https://doi.org/10.1007/s11458-008-0005-4
Lipopolysaccharide (LPS) is a major component of the outer membrane of all gram-negative bacteria. It interacts with some biomolecules and triggers a toxic reaction. In this paper, we studied the interaction between LPS from Salmonella Minnesota and some biomolecules using a surface plasmon resonance (SPR) biosensor. Biomolecules were immobilized on a CM5 sensor chip using the amino coupling method and LPS was injected over the immobilized surfaces. The affinity constant KA of LPS with serum albumin, hemoglobin, chitosan and lysozyme was 2.36 × 107, 2.03 × 108, 7.58 × 106, 2.82 × 104 L·mol-1, respectively. However, LPS could not interact with ferritin.
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Synthesis, crystal structure and
magnetic properties of single-molecule magnet: [Mn(CFCOO)(hmp)]
WANG Bing, NA Liyan, ZHANG Fengjie, NING Guiling
Front. Chem. China. 2008, 3 (1): 23-26.
https://doi.org/10.1007/s11458-008-0015-2
The preparation, X-ray structure and magnetic properties are presented for a new mixed-valence tetranuclear manganese complex that functions as a single-molecule magnet (SMM): [Mn4(CF3COO)4(hmp)6], where hmp- is the anion of 2-(hydroxymethyl) pyridine and is a N,O bidentate chelate. The compound crystallizes in a monoclinic system, space group P21/c (No. 14) with unit cell parameters a = 13.663(3) Å, b = 14.705(3) Å, c = 14.734(3) Å, ? = 98.51(3)°, V = 2927.6 Å3 and Z = 2. The structure of the complex shows a novel coordination of the trifluoroacetate (TFA) anions, with one anion acting as a monodentate ligand while the second one coordinating through both oxygens to the same Mn center. Direct current magnetic susceptibility measurement in the 2–300 K temperature range supports a high-spin ground state. The presence of a frequency-dependent alternating current susceptibility signal indicates that the individual molecule is acting as magnet.
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Adsorption of reactive brilliant
red K-2BP on activated carbon developed from sewage sludge
XIE Jiankun, YUE Qinyan, YU Hui, YUE Wenwen, LI Renbo, ZHANG Shengxiao, WANG Xiaona
Front. Chem. China. 2008, 3 (1): 33-40.
https://doi.org/10.1007/s11458-008-0014-3
Activated carbon was prepared from the sewage sludge of municipal wastewater treatment plant by chemical activation (activation reagent is ZnCl2) and was used for the adsorption of dye (reactive brilliant red K-2BP). The impact of adsorbent amount, adsorption time and pH value on adsorption effect, the adsorption kinetics, and the adsorption thermodynamics were discussed according to batch adsorption tests. The results indicated that the activated carbon developed from sewage sludge (ACSS), which was mesoporous, possessed opened porous structures. The iodine number of the ACSS was 326 mg·g-1. The rate of achievement was 51.31%. The BET surface area was 298 m2·g-1 and the contents of heavy metals in the leachate didn’t exceed the contents limit. The adsorption kinetics of reactive brilliant red K-2BP on the ACSS was accorded with the two-step kinetics rate equation and pseudo-second-order kinetics equation. Compared to the Freundlich isotherm equation, the Langmuir isotherm equation showed better applicability for the adsorption. The adsorption which was favorable was an endothermic (enthalpy ?H > 0) and spontaneous (free energy ?G < 0) process and was accompanied by an increase in entropy (?S > 0).
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Research on multiphase synthesis
of 1,5-di(-anisidino)anthraquinone
YU Liqiu, HE Liang, ZHANG Shufen, YANG Jinzong
Front. Chem. China. 2008, 3 (1): 47-51.
https://doi.org/10.1007/s11458-008-0008-1
According to the Ullman reaction mechanism, the synthesis of 1,5-di(o-anisidino)anthraquinone was achieved by the multiphase reaction of 1,5-dichloroanthraquinone in xylene and o-anisidine in the presence of copper metal powder and potassium acetate. The effects of various factors on the reaction, such as the dosages of xylene and catalyst, molar ratios of raw materials, and reaction times were investigated. When the molar ratio of 1,5-dichloroanthraquinone to o-anisidine and potassium acetate is 1:10:2.5 and the catalyst dosage based on 1,5-dichloroanthraquinone is 5.3%, the conversion of 1,5-dichloroanthraquinone is 97.8% and the yield of 1,5-di(o-anisidino)anthraquinone is 80.6% after reflux for 10 h. Under these conditions, the recovery of the solvent is 86.0%. The target compound was identified by MS, 1H NMR, IR and DSC.
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Studies on CMC and thermodynamic
function of anionic surfactants in DMA/long-chain alcohol systems
using microcalorimetric method
ZHANG Honglin, KONG Zhe, YAN Yongmei, YU Li, LI Zhen
Front. Chem. China. 2008, 3 (1): 57-63.
https://doi.org/10.1007/s11458-008-0016-1
The critical micelle concentration (CMC) and the thermodynamic function of the anionic surfactant, sodium laurate (SLA) and sodium dodecyl sulfate (SDS) in the N,N-dimethyl acetamide (DMA)/long-chain alcohol systems were studied using titration microcalorimetric method. The power-time curves of SLA and SDS in the presence of a long-chain alcohol (n-heptanol, n-octanol, n-nonanol, n-decanol) in the DMA medium were determined. Then, from the curves, the critical micelle concentration (CMC) and the thermodynamic standard formation functions (?H?m, ?G?m and ?S?m) were obtained through thermodynamic theories. The relationships between temperature, alcohol’s carbon number, concentration and thermodynamic properties were discussed. For SLA or SDS in a DMA solution, under the same concentration of alcohol, the values of CMC, ?H?m and ?S?m increase, while the values of ?G?m decrease with the increase of temperature. Under the same condition of identical temperature and alcohol concentration, the values of CMC, ?H?m, ?G?m and ?S?m decrease with the increase of the alcohol’s carbon number. In the presence of the same kind of alcohol, the values of CMC and ?G?m increase, but the values of ?H?m and ?S?m decrease with the concentration increases in alcohol series at the same temperature.
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Effect of TiO-coating on structure and electrochemical performance of LiCoNiMnO
ZHANG Xinxiang, YANG Xiao, HUANG Youyuan, ZHOU Henghui, CHEN Jitao
Front. Chem. China. 2008, 3 (1): 64-69.
https://doi.org/10.1007/s11458-008-0020-5
LiCo0.2Ni0.4Mn0.4O2, as the cathode material for lithium ion batteries, was modified by TiO2-coating. The effect of TiO2-coating on the structure and electrochemical performance of LiCo0.2Ni0.4Mn0.4O2 was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and galvanostatic charge-discharge tests. The results suggest that a small amount of TiO2-coating does not change the crystalline structure, but considerably improves the electrochemical performance of LiCo0.2Ni0.4Mn0.4O2 in terms of capacity delivery and cyclability. XPS measurements confirm that the improved electrochemical performance is most possibly attributed to a decrease in interaction between the layered material and non-aqueous electrolyte during the charge-discharge processes.
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Study on eruption of heat for B aroused by lanthanum nitrate
and its mechanism
LU Yan, LIU Guosheng, LIU Yi, RAN Zhilin, WANG Hailei, SHEN Ping
Front. Chem. China. 2008, 3 (1): 70-75.
https://doi.org/10.1007/s11458-008-0010-7
Biological effect of rare-earth lanthanum nitrate on the growth of Escherichia coli B was studied using the calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentrations of lanthanum nitrate. For example, the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) are evidently increased when compared with normal E. coli B cultures. When the concentration of lanthanum nitrate was at 300 mg/L and 500 mg/L, the Q of the cultures reached 3.89 and 2.54 times of normal cultures, respectively. The survivability of cells and the biomass of the cultures were measured using biological methods and the results show that the growth and multiplication of cells were inhibited and that the biomass decreased at high concentration of lanthanum nitrate. These revealed that the inhibiting cells discharged more quantity of heat than the normal growing cells. We named this phenomenon as “eruption of heat”. It was suggested that the mechanism for the eruption of heat was that La3+ ion damages the outer cell membrane and increases its permeability and the proton-electron potential energy across the cell membrane was reduced or couldn’t even be initiated. Energy could not be translated into ATP effectively in the course of oxidative phosphorylation resulting in heat release. So, the growth of the cells was inhibited due to scarceness of energy ATP.
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Synthesis of ZnS hollow nanospheres
with holes using different amine templates
TANG Yu, ZHANG Yuanming, YANG Jun, DU Biying, LI Lingang
Front. Chem. China. 2008, 3 (1): 76-80.
https://doi.org/10.1007/s11458-008-0022-3
ZnS hollow nanospheres with holes were prepared by reacting ZnSO4 with H2S, the sulfide source formed in the reaction of CS2 with ethylenediamine, 1,3-propylenediamine, butylamine or 2-(2-aminoethylamino) ethanol, which also acted as a template agent, at 50°C under agitation. The shape, particle size of about 100–850 nm and hole size of about 150–600 nm of ZnS hollow nanospheres with holes were shown by SEM and TEM images. These ZnS nanospheres with ? cubic ZnS phase and composed of 2–5 nm nanocrystals were characterized by XRD and HRTEM. The blue shift of maximum absorption in UV-vis displayed the effect of quantum size. The two amino groups of amine templates reacted favorably with Zn2+ to form uniform and relatively smooth ZnS nanospheres with holes, while hydroxyethyl played a disadvantageous role. A reasonable mechanism of hole formation by H2S rushing out is suggested.
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Interaction between bovine serum
albumin and Indo-1 using fluorescence spectroscopic method
Haixin BAI, BAI Haixin, YANG Cheng, YANG Xiurong
Front. Chem. China. 2008, 3 (1): 105-111.
https://doi.org/10.1007/s11458-008-0013-4
This work attempts to calculate the binding-site number using fluorescence spectroscopic method with bovine serum albumin (BSA) and Indo-1 as protein and ligand models, respectively. The method for calculating the binding-site number in BSA for Indo-1 was developed based on the relationships between changes in Indo-1 fluorescence intensity and the analytical concentration of BSA. The interaction between BSA with Indo-1 was investigated comprehensively using fluorescence techniques as well as fluorescence resonance energy transfer, and the thermodynamic parameters were calculated according to the effect of enthalpy on temperature. Three binding sites in BSA for Indo-1 were revealed, and the distances from Trp212 in BSA to the three binding sites were 2.93, 2.57 and 2.40 nm, respectively. It was also proven that Indo-1 embedded into the three hydrophobic cavities of BSA by hydrophobic association. This paper provides a reference on calculating the binding-site number in proteins for ligands and studying their interactions by fluorescence spectroscopic methods. In fluorescent quenching experiments, fluorescence changes were automatically recorded in real time by combining the Microlab 500 Series Dispenser and PTI fluorescence apparatus.
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Effect of solvents on propylene
epoxidation over TS-1 catalyst
MI Zhentao, SU Xueli, WU Yulong, LIU Qingshan
Front. Chem. China. 2008, 3 (1): 112-117.
https://doi.org/10.1007/s11458-008-0007-2
Solvents have an important effect on the epoxidation of propylene catalyzed by TS-1. The experimental results show that, in different solvents, the catalytic activity of epoxidation is in the following order: methanol > 2-propanol > 2-butanol > acetonitrile > acetone > tetrahydrofuran. Based on the reaction mechanism, the effects of solvents on the epoxidation were studied from eight aspects, which included the electronic effect, the steric effect, the polarity of solvent, the effect of solvent on sorption and diffusion of reactant, the oxidation of alcohol, the etherification of PO, the deactivation of TS-1 and the solubility of propylene in the solvents. The electronic effect, steric effect and the polarity of solvent were considered to be the main aspects. This work may provide theoretical guidance for choosing solvents for these kinds of reactions and also may serve as basis for further industrialization.
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Design, synthesis and hypoglycemic
activity of 3-methyl-1-phenyl-4-{4-[(5-methyl-2-phenyloxazol-4-yl)methoxy]benzylene(benzyl)}-2-pyrazol-5-one
LIU Xing, WANG Yalou, WU Guanzhong, LI Jiangchuan, WU Xiaoyan
Front. Chem. China. 2008, 3 (1): 118-123.
https://doi.org/10.1007/s11458-008-0006-3
Based on the SAR (structure activity relationship) of TZDs (thiazolidinediones), 3-methyl-1-phenyl-2-pyrazoline-5-one was selected as a substitute for TZD. Compounds of 3-methyl-1-phenyl-4-{4-[(5-methyl-2-phenyloxazol-4-yl)methoxy]benzylene(benzyl)}-2-pyrazol-5-one were designed and synthesized to find some more hypoglycemic active agents and further investigate the SAR of this class of compounds. Butanedione monoxime reacted with (substituted) benzaldehyde via cyclization and chlorination to give 4-(chloromethyl)-5-methyl-2-phenyloxazole derivatives, which condensed with 4-hydroxybenzaldehyde or vanillin, and was followed by the Knoevenagel reaction with 3-methyl-1-phenyl-2-pyrazol-5-one to give compounds Ia–Ih. Compounds Ia–Ih were hydrogenated with Pd–C to give IIa–IIh, and their hypoglycemic activity was evaluated with a glucose oxidase kit and insulin load test on normal mice. Sixteen new target compounds were synthesized. All the compounds were characterized by 1H NMR, IR, MS and elemental analysis. The preliminary pharmacological tests show that the compounds have good hypoglycemic activity and can enhance the action of insulin, especially Ib, Id and If.
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22 articles
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