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25 March 2008, Volume 24 Issue 2

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Content of Chemical Research in Chinese Universities Vol.24 No.2(2008)

2008, 24(2):  0-0.  doi:

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Articles

Synthesis and Spectroscopic Properties of a Series of New tetra-Substituted Metal Phthalocyanines

YU Hai-ling, YANG Jin, FU Qiang, MA Ji-cheng , LI Wei-li

2008, 24(2):  123-128.  doi:

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A new class of metal phthalocyanines(MPcs) containing four 8-quinolinol(8-QH) derivative moieties were successfully synthesized and characterized by mass spectroscopy, IR, UV-Vis and element analysis, the results of which were consistent with the proposed structures. All of them can dissolve in common organic solvents, such as dichloromethane, chloroform, and acetone. The effect of metal ion on the absorption of Q band was studied with UV-Vis spectra. The fluorescent properties for those complexes were also investigated.

New Inorganic-organic Hybrid Compound Containing One Dimensional Keggin Polyoxometalate [SiW₁₁O₃₉Co]⁶⁻ Chains: Preparation, Characterization and Application in Chemically Bulk-modified Electrode

WANG Xiu-li, LIN Hong-yan, LIU Guo-cheng, CHEN Bao-kuan , BI Yan-feng

2008, 24(2):  129-134.  doi:

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A new inorganic-organic hybrid compound based on polyoxometalate and organic ligand formulated as (H₂bpp)₃[SiW₁₁O₃₉Co]·~2H₂O(1)[bpp=1,3-bis(4-pyridyl)propane] was hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR, TG, and cyclic voltammetry. Single-crystal X-ray diffraction analysis reveals that compound 1 consists of interesting cobalt-monosubstituted POMs one dimensional chain together with protonated bpp ligands. Additionally, the polyoxoanions combined with the discrete organic substrates by hydrogen bond interactions to afford a supramolecular 3D network structure. The hybrid compound 1 was used as a bulk modifier to fabricate a three-dimensional chemically modified carbon paste electrode(1-CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1-CPE were studied in detail. The results indicate that 1-CPE has good electrocatalytic activities toward the reduction of nitrite or bromate in 1 mol/L H2SO4 aqueous solution. 1-CPE shows remarkable stability that can be ascribed to the insolubility of compound 1 and the supramolecular interactions existed between 1D POM anion chains and organic ligand bpp, which is very important for practical applications in electrode modification.

Synthesis of ZrSiO₄ and Coesite in SiO₂-ZrO₂ System Under High Pressure

XUE Yan-feng , XU Da-peng , ZHANG Guang-qiang , ZHOU Xian-feng , DING Zhan-hui , LIU Xiao-mei , SU Wen-hui,

2008, 24(2):  135-137.  doi:

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ZrSiO₄ and coesite were obtained under high-pressure and high-temperature from the nano precursor of α-SiO₂ and ZrO₂. XRD and Raman measurements indicate that ZrSiO₄ was formed at a temperature higher than 920 °C under a pressure of 3.6 GPa. As the pressure increased to 3.9 GPa, the ZrSiO₄ formation temperature was reduced to 815 °C. The formation temperature for coesite was 990 °C under 3.9 GPa. The lower formation temperature for ZrSiO₄, as compared to that for coesite, provided an experimental evidence that the coesite in the Earth’s surface usually occurs as inclusions in ZrSiO₄.

Aptamer-based Electrochemical Biosensors for Highly Selective and Quantitative Detection of Adenosine

ZHENG Fan, WU Zai-sheng, ZHANG Song-bai, GUO Meng-meng, CHEN Chen-rui, SHEN Guo-li , YU Ru-qin

2008, 24(2):  138-142.  doi:

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A new adenosine biosensor based on aptamer probe is introduced in this article. An amino-labeled aptamer probe was immobilized on the gold electrode modified with an o-phenylenediamine electropolymerized film. When adenosine is bound specifically to the aptamer probe, the interface of the biosensor is changed, resulting in the decrement of the peak current. The response current is proportional to the amount of adenosine in sample. The used electrode can be easily regenerated in hot water. The proposed biosensor represents a linear response to adenosine over a concentration range of 1.0×10⁻⁷—1.0×10⁻⁴ mol/L with a detection limit of 1.0×10⁻⁸ mol/L. The presented biosensor exhibits a nice specificity towards adenosine. It offers a promising approach for adenosine assay due to its excellent electrochemical properties that are believed to be very attractive for electrochemical studies and electroanalytical applications.

Simple, Selective, and Sensitive Spectrophotometric Method for Determination of Trace Amounts of Nickel(II), Copper (II), Cobalt (II), and Iron (III) with a Novel Reagent 2-Pyridine Carboxaldehyde Isonicotinyl Hydrazone

Sajid H. Guzar , JIN Qin-han

2008, 24(2):  143-147.  doi:

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A selective and sensitive reagent of 2-pyridine carboxaldehyde isonicotinyl hydrazone(2-PYAINH) was synthesized and studied for the spectrophotometric determination of nickel, copper, cobalt, and iron in detail. At a pH value of 7.0, 9.0, 9.0, and 8.0, respectively, which greatly increased the selectivity; nickel, copper, cobalt, and iron reacted with 2-PYAINH to form a 1:2 yellow-orange, 1:2 yellow-green, 1:2 yellow and 1:1 yellow complexes, with absorption peaks at 363, 352, 346, and 359 nm, respectively. Under the optimal conditions, Beer’s law was obeyed over the ranges of 0.01―1.4, 0.01―1.5, 0.01―2.7, and 0.01―5.4 mg/L, respectively. The apparent molar absorptivity and Sandell’s sensitivities were 8.4×10⁴, 5.2×10⁴, 7.1×10⁴, and 3.9×10⁴ L·mol^-1·cm^-1, respectively, and 0.00069, 0.0012, 0.00078, and 0.0014 µg·cm^-2, respectively. The detection limits were found to be 0.001, 0.002, 0.003, and 0.01 mg/L, respectively. The detailed study of various interfering ions to make the method more sensitive was carried out and selective and several real samples were analyzed with satisfactory results.

Quality Analysis of Herbal Medicine Products Prepared from Herba Sarcandrae by Capillary Electrophoresis with Electrochemical Detection

ZHOU Xiao-guang , SUN Jin-ying , ZHU De-rong , YUAN Bai-qing , YOU Tian-yan

2008, 24(2):  148-153.  doi:

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A capillary electrophoresis with electrochemical detection(CE-ED) method was developed for the quality analysis of herbal medicine products prepared from the same herb of Herba Sarcandrae: Fufang Caoshanhu tablets, Qingrexiaoyanning capsules, and Xuekang oral liquids. Under the optimal analysis conditions, the low detection limit[1.0×10⁻⁷ mol/L(S/N=3)] and the wide linear range(1.0×10⁻⁷―1.0×10⁻⁴ mol/L) were obtained for quality standard compound of isofraxidin. The precisions of the peak current and the migration time(as RSDs) for the real sample analysis were 2.0%―2.6%, and 1.2%―1.8% for isofraxidin, respectively. The contents of isofraxidin detected were 15.77 μg/tablet, 0.48 mg/capsule, 1.2 mg/ampoule(Jiangxi), and 0.44 mg/ampoule(Dalian) for Fufang Caoshanhu tablets, Qingrexiaoyanning capsules, and Xuekang oral liquids from different manufacturers, respectively. Quality estimate was conducted by comparing the contents of isofraxidin in the herbal medicine products with the demanded values of Chinese pharmacopeia. In addition, based on their own unique CE-ED profiles(namely, CE-ED electropherograms) the Xuekang oral liquids from the different manufacturers could be easily identified.

Adsorption of Human Serum Albumin onto PVA-coated Affinity Microporous PTFE Capillary

JIN Gu, YAO Qi-zhi , ZHANG Lei

2008, 24(2):  154-161.  doi:

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Affinity dye-ligand Cibacron Blue F3GA(CB F3GA) was covalently coupled with poly(vinyl alcohol)(PVA) coated on the inner surface of microporous poly(tetra-fluoroethylene)(MPTFE) membranous capillary. The PVA-coated PTFE capillary surface was characterized by XPS and FESEM. The grafting degree of PVA and the amount of CB F3GA immobilized onto the membranous capillary were 23.5 mg/g and 89.6 μmol/g, respectively. These dyed membranous capillaries were chemically and mechanically stable, and could be reproducibly prepared. Human serum albumin(HSA) was selected as model protein. The saturation adsorbance of the dye attached membranous capillary was 85.3 mg HSA/g, while the capacity of non-specific adsorption for HSA was less than 0.3 mg/g.

Qualitative and Semi-quantitative Analysis of Quaternary Alkaloids in Coptis-scute Herb Couple by Electrospray Mass Spectrometry

LI Wei , SONG Feng-rui , LIU Zhi-qiang , LIU Shu-ying

2008, 24(2):  162-166.  doi:

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A practical solution of qualitatively analyzing quaternary alkaloids in coptis-scute herb couple by electrospray ionization mass spectrometry(ESI-MS) was developed. Without the complicated pretreatment of sample, the active ingredients including berberine, palmatine, coptisine, jatrorrhizine, epiberberine, and columbamine were identified and some relative content changing rules of alkaloids in coptis-scute couple were summarized in this article. The overall profiles of the complex extracts were obtained. After adding an internal standard(rutaecarpine), semi-quantitative analysis was performed and the result indicates that the actual content of alkaloids was decreased by increasing the amount of scute. Based on the data obtained by high-performance capillary electrophoresis(HPCE), the feasibility of semi-quantitative analysis by ESI-MS was further proved.

Component Analysis and Free Radicals Scavenging Activity of Physalis alkekengi L. Polysaccharide

CHENG Ying-kun, LI Lei, MENG Zhao-kun, HOU A-li, WU Yu-jie , TENG Li-rong

2008, 24(2):  167-170.  doi:

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A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide(PAP) was composed of rhamnose, xylose, arabinose, galactose, and glucose. Free radicals scavenging activity of PAP was studied through 3 free radicals scavenging tests. PAP exhibited high scavenging effects on ^·OH and DPPH radicals, and both the scavenging rates were about 80%. The scavenging rate of ^·O₂⁻ radical was about 22%.

New Active Organic Substance in Oyster Shell Capable of Scavenging Oxygen Free Radicals with High Efficiency

MA Jian-hua

2008, 24(2):  171-174.  doi:

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A light purple organic active substance capable of scavenging hydroxyl radical(^·OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge ^·OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical(O₂^−·) although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.

Diels-Alder Addition of Dicyclopentadiene with Cyclopentadiene in Polar Solvents

ZHANG Xiang-wen, JIANG Qiang, XIONG Zhong-qiang, ZOU Ji-jun, WANG Li , MI Zhen-tao

2008, 24(2):  175-179.  doi:

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Diels-Alder addition of dicyclopentadiene and cyclopentadiene in polar solvents has been studied to produce tricyclopentadiene(TCPD) that is a potential high-density fuel precursor. GC and MS analysis shows that the adducts contain two isomers, namely exo- and endo-TCPD. Theoretical simulation shows that although the transition state of endo-TCPD has a lower activation energy, exo-TCPD is thermodynamically preferred. Polar solvents can accelerate the reaction rate and improve the exo/endo ratio of TCPD because the transition state of exo-TCPD has a higher polarity than that of endo-TCPD. The solvent effect follows the order of polarity: benzyl methanol>cyclohexanone>toluene. The conversion rises when the temperature ranges from 120 to 150 °C, but the selectivity of TCPD slightly decreases. Increasing the pressure can improve the conversion but the exo/endo ratio of TCPD is unchanged. The apparent kinetics in different solvents was determined via nonlinear regression. The activation energies are 99.47, 101.15, and 107.32 kJ/mol for benzyl methanol, cyclohexanone, and toluene, respectively. The optimal reaction conditions are as follows: benzyl methanol as solvent, temperature 150 °C, and pressure 900 kPa. After an 11-hour reaction, a conversion of 58.0%, a TCPD selectivity of 95.7%, and an exo/endo ratio of 1/5.3 has been obtained.

Organometallic Gold(III) Derivatives with Anionic Oxygen Ligands-mononuclear Hydroxo, Alkoxo, and Acetato Complexes: Synthesis and Spectral Study

Prithwiraj Byabartta

2008, 24(2):  180-186.  doi:

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A variety of gold(III) adducts having σ-ligated oxygen-donor ligands have been prepared from [Au(ppy)Cl₂](ppy·phenylpyridine)(1) either by partial or total replacement of the chloride ions. The new species comprise hydroxo-[Au(ppy)(OH)Cl](2), and [Au(ppy)(OH)₂](3), oxo-[Au₂(ppy)₂(μ-O)₂](4), acetate-[Au(ppy)(O₂CMe₂)] (5), and alkoxo complexes-[Au(ppy)(OR)Cl](6, 7) and [Au(ppy)(OR)₂](8―10)(R=Me, 6 and 8; Et, 7 and 9; Prⁱ, 10). The dihydroxo and the oxo complexes can be interconverted by refluxing the former in anhydrous THF and the latter in water. The hydroxides 2 and 3 and the acetato complex 5 undergo σ-ligand metathesis in ROH solution(R=Me, Et or Prⁱ) to give the corresponding alkoxides.

Activation of CFTR-mediated Cl⁻ Transport by Magnolin

JIN Ling-ling , LIU Xin , SUN Yan , LIN Sen , ZHOU Na , XU Li-na , YU Bo , HOU Shu-guang , YANG Hong

2008, 24(2):  187-191.  doi:

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Magnolin is a herbal compound from Magnolia biondii Pamp. It possesses numerous biological activities. Cystic fibrosis transmembrane conductance regulator(CFTR) is an epithelial chloride channel that plays a key role in the fluid secretion of various exocrine organs. In the present study, the activation of CFTR-mediated chloride transport by magnolin is indentified and characterized. In CFTR stably transfected FRT cells, magnolin increases CFTR Cl⁻ currents in a concentration-dependent manner. The activation of magnolin on CFTR is rapid, reversible, and cAMP-dependent. Magnolin does not elevate cellular cAMP level, indicating that it activates CFTR by direct binding and interaction with CFTR protein. Magnolin selectively activates wildtype CFTR rather than mutant CFTR. Magnolin may present a novel class of therapeutic lead compound for the treatment of diseases associated with reduced CFTR function such as keratoconjunctivitis sicca, idiopathic chronic pancreatiti, and chronic constipation.

Expression, Purification and Spectral Characterization of p21^Waf1/Cip1

SHI Qiao-yun , ZHENG Yong-chen , REN Jin-song , QU Xiao-gang

2008, 24(2):  192-195.  doi:

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p21^Waf1/Cip1, best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, can interact with various target proteins, and this ability relies on its structural plasticity. Therefore, studies on the structural properties of p21 are very important to understand its structure-function relationship. However, detailed studies on its secondary structure and biophysical properties have been comparatively sparse. A human p21 gene was cloned into the temperature expression vector pBV220 and transformed into Escherichia coli strain JM109. Recombinant protein was expressed as a non-fusion protein and purified by gel filtration and anion exchange chromatography. The purified protein was verified by Western blot and the functional activity was recognized by pull-down assay. Furthermore, circular dichroism, fluorescence spectroscopy, and fluorescence quenching methods were used to characterize the conformational properties of the purified protein. The results indicate that it was largely unstructured under the native solution conditions, and its tryptophan residues were exposed and located in a positively charged microenvironment. This study lays a good foundation for further study of p21 binding to its different partners.

Preparation, Characterization, and in vitro Release of Biodegradable Erythromycin-gelatin Microspheres

WANG Fei , LIU Pai , JIANG Dan , LIU Cheng-bai , ZHANG Feng-chun , CHEN Xia

2008, 24(2):  196-199.  doi:

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Blank and erythromycin-loaded gelatin microspheres were successfully fabricated via emulsion chemical- crosslinking technique. The surface morphology of the microspheres was characterized by scanning electron microscope(SEM) and optical microscope. The results show that the microspheres were spherical and smooth. The particle average size of erythromycin-loaded microspheres was found to be 20.6 μm, with a high purity of more than 90% and with a good dispersibility. The microspheres could be obtained in a high yield. Erythromycin released from the microspheres was monitored in buffer and artificial body fluid at 37 °C. Average drug content was 27.2%, and erythromycin-loaded gelatin microspheres showed good release profiles with a nearly constant release during 4―8 h in artificial body fluid in vitro degradation studies. These gelatin microspheres are useful for studying and developing various drug-delivery systems.

Natural Compound Curcumin—a Channel Potentiator Rather Than a Corrector of the Defective Intracellular Processing of ∆F508 Mutant Cystic Fibrosis Transmembrane Conductance Regulator

LIU Xin , GUAN Li , HE Cheng-yan , ZHANG Xiao-jing , XU Li-na , SHANG De-jing , MA Tong-hui , YANG Hong

2008, 24(2):  200-203.  doi:

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Cystic fibrosis(CF) is a severe genetic disease caused by the gene mutation of the cystic fibrosis transmembrane conductance regulator(CFTR) chloride channel. The most common point mutation ∆F508, which leads to impaired intracellular processing and channel gating of CFTR, appears in about 90% CF patients. The natural compound curcumin was reported to correct the processing defect of ∆F508-CFTR and proposed as a potential therapeutic drug to cure CF. In the present study, we analyzed the effect of curcumin on ∆F508-CFTR and demonstrated that curcumin can restore the impaired chloride conductance of ∆F508 mutant CFTR. The activity is rapid, reversible and cAMP-dependent. However, we couldn’t reproduce the previously reported correction of the defective membrane trafficking of ∆F508-CFTR by curcumin. Therefore, curcumin may not be a superior lead compound for developing anti-CF drugs.

Osmotic Regulation of Betaine Content in Leymus chinensis Under Saline-alkali Stress and Cloning and Expression of Betaine Aldehyde Dehydrogenase(BADH) Gene

CUI Xi-yan , WANG Yong , GUO Ji-xun

2008, 24(2):  204-209.  doi:

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The potted Leymus chinensis seedlings were treated with saline-alkali solution of six different(from I to VI) concentrations. The results demonstrate that the betaine content and Betaine-aldehyde dehydrogenase(BADH: EC 1.2.1.8) activities have a direct relation with increased stressing time in the same treatment; both exhibit a single peak with increasing the concentration of saline-alkali solution, and number V shows the highest value. The BADH gene of Leymus chinensis was cloned by RT-PCR and RACE technology and was designated as LcBADH. The cDNA sequence of LcBADH was 1774bp including the open reading frame(ORF) of 1521bp(coding 506 amino acids). The vector of prokaryotic expression was constructed by inserting the LcBADH gene fragment into pET30a(+) and transformed into E. coli BL21(DE3). The result of SDS-PAGE shows that the idio-protein with a molecular mass of 56.78 kDa was effectively expressed in the recombinant bacteria induced by isopropyl β-D-thiogalactoside(IPTG).

Nonisothermal Kinetics of Dehydration Process of [Sm(m-ClBA)₃phen]₂·2H₂O and [Sm(p-ClBA)₃phen]₂·2H₂O

REN Ning , WANG Xi-e , ZHANG Jie , ZHANG Jian-jun , XU Su-ling , ZHANG Hai-yan

2008, 24(2):  210-214.  doi:

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Compounds [Sm(m-ClBA)₃phen]₂·2H₂O and [Sm(p-ClBA)₃phen]₂·2H₂O(m-ClBA=m-chlorobenzoate, p-ClBA=p-chlorobenzoate, phen=1,10-phenanthroline) were prepared. The dehydration processes and kinetics of these compounds were studied from the analysis of the DSC curves using a method of processing the data of thermal analysis kinetics. The Arrhenius equation for the dehydration process can be expressed as lnk=38.65−243.90×10³/RT for [Sm(m-ClBA)₃phen]₂·2H₂O, and ln k=38.70−172.22×10³/RT for [Sm(p-ClBA)₃phen]₂·2H₂O. The values of ΔH^≠, ΔG^≠, and ΔS^≠ of dehydration reaction for the title compounds are determined, respectively.

Resistivity-Temperature Behavior of CB-Filled HDPE Foaming Composites

LI Ji-xin, , ZHANG Guo , LI Zhuo-shi , WANG Xin-lei , LIU Xiu-qi

2008, 24(2):  215-219.  doi:

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High-density polyethylene/carbon black foaming conductive composites were prepared from acetylene black(ACET) and super conductive carbon black(HG-1P) as conductive filler, low-density polyethylene(LDPE) as the second component, ethylene-vinyl acetate(EVA) and ethylene propylene rubber(EPR) as the third component, azobisformamide(AC) as foamer, and dicumyl peroxide(DCP) as cross-linker. The structure and resistivity-temperature behavior of high-density polyethylene(HDPE)/CB foaming conductive composites were investigated. Influences of carbon black, LDPE, EVA, EPR, AC, and DCP on the foaming performance and resistivity-temperature behavior of HDPE/CB foaming conductive composites were also studied. The results reveal that HDPE/CB foaming conductive composite exhibits better switching characteristic; ACET-filled HDPE foaming conductive composite displays better positive temperature coefficient(PTC) effect; whereas super conductive carbon black(HG-1P)-filled HDPE foaming conductive composite shows better negative temperature coefficient(NTC) effect.

Theoretical Studies on Structures and Properties of Endohedral Fullerenes Complexes: XH_n@C₃₂(X=F, O, N, C; n=1―4)

CHANG Ying-fei, HONG Bo, SUN Li-li, TANG Shu-wei , WANG Rong-shun

2008, 24(2):  220-222.  doi:

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Theoretical studies on structures and properties of endohedral fullerene complexes formed by encapsulating small molecules of HF, H₂O, NH₃, and CH₄ in a C₃₂ fullerene cage, were carried out by ab initio method. Current calculations reveal that these processes to encase them in fullerene are energetically unfavorable because of the small cavity size of C₃₂. The red shift in the F―H stretching frequency indicates the potential existence of hydrogen bonding between the HF molecule and the carbon cage.

Quasi-Classical Trajectory Study of the Chemical Reaction Ca+CH₃I

ZHANG Zhi-hong , CHEN Mao-du , CONG Shu-lin

2008, 24(2):  223-225.  doi:

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The Ca+CH₃I→CaI+CH₃ reaction system has been studied with the quasi-classical trajectory method on the extended Lond-Eyring-Polanyi-Sato(LEPS) potential energy surface. At collision energy E_col=10.78 kJ/mol, the calculated results show that the CaI vibrational population peaks are located at ν=2. The calculated cross section decreases slowly with the collision energy increasing. The angle product distributions tend toward backward scattering. The calculated〈P₂(J′·K)〉values deviate slightly from −0.5 and decrease with increasing collision energy. The Quasiclassical trajectory calculation(QCT) results are in reasonable agreement with experimental data. Moreover, the dynamics of the reaction has been discussed.

Cerium Salt Promoted Homocoupling Reaction of Dialkylanilines in Water

YANG Xiang-hua, LU Wen-chao, LIAO Qian , XI Chan-juan

2008, 24(2):  226-230.  doi:

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Highly regioselective homocoupling of N,N-dialkylanilines can be achieved in water with cerium reagents, in which various N,N,N′,N′-tetraalkylbenzidines are obtained from N,N-dialkylanilines either by direct oxidation by cerium(IV) reagents or by cerium(III) reagents in the presence of hydroperoxide.

Immobilization and Properties of Lipase from Candida rugosa on Electrospun Nanofibrous Membranes with Biomimetic Phospholipid Moities

HUANG Xiao-jun, YU An-guo, GE Dan , XU Zhi-kang

2008, 24(2):  231-237.  doi:

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Reported here is a protocol to fabricate a biocatalyst with high enzyme loading and activity retention, from the conjugation of electrospun nanofibrous membrane having biomimetic phospholipid moiety and lipase. To improve the catalytic efficiency and activity of the immobilized enzyme, poly(acrylonitrile-co-2-methacryloyloxyethyl phosphorylcholine)s(PANCMPCs) were, respectively, electrospun into nanofibrous membranes with a mean diameter of 90 nm, as a support for enzyme immobilization. Lipase from Candida rugosa was immobilized on these nanofibrous membranes by adsorption. Properties of immobilized lipase on PANCMPC nanofibrous membranes were compared with those of the lipase immobilized on the polyacrylonitrile(PAN) nanofibrous and sheet membranes, respectively. Effective enzyme loading on the nanofibrous membranes was achieved up to 22.0 mg/g, which was over 10 times that on the sheet membrane. The activity retention of immobilized lipase increased from 56.4% to 76.8% with an increase in phospholipid moiety from 0 to 9.6%(molar fraction) in the nanofibrous membrane. Kinetic parameter K_m was also determined for free and immobilized lipase. The K_m value of the immobilized lipase on the nanofibrous membrane was obviously lower than that on the sheet membrane. The optimum pH was 7.7 for free lipase, but shifted to 8.3―8.5 for immobilized lipases. The optimum temperature was determined to be 35 °C for the free enzyme, but 42―44 °C for the immobilized ones, respectively. In addition, the thermal stability, reusability, and storage stability of the immobilized lipase were obviously improved compared to the free one.

Mixed Pyridine-phenol Boron Complex Encapsulated in Polymer/Silica Hybrid Sol-gel Matrix

DONG Wei , TANG Jun , WANG Yue

2008, 24(2):  238-240.  doi:

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A novel pyridine-phenol boron complex[(dppy)BF] was encapsulated into polymer/silica composite matrix by sol-gel process. UV-Vis absorption spectra show that this process can control the aggregation structure of complex (dppy)BF. The results of photoluminescence of (dppy)BF in sol-gel composite film indicate that both fluorescence intensity and photostability are markedly increased using this method compared with other methods, which increases the practical significance of such composite film.

Theoretical Study on the Conformational Conversion of 1,3-Dioxane Inside a Capsular Host

WANG Ju, YANG Zuo-yin, WANG Xiu-li, ZHANG Jing-chang , CAO Wei-liang

2008, 24(2):  241-245.  doi:

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The mechanism for the conformational conversion of 1,3-dioxane guest encapsulated inside a capsular host was theoretically investigated using semiempirical PM3 method and DFT methods. The free-state process of the conformational conversion of 1,3-dioxane was also investigated to make a comparison between the two different states using the same theory. The influences of the inner phase of the capsule on the conformational conversion of guest molecule were discussed via analyzing the comparative results. It was found that the capsular host could accommodate 1,3-dioxane within its cavity by the weak attractive interactions between host and guest, and it responds to the conformational conversion of guest by the deformation of hydrogen-bonding seam at the middle of the capsule. When entrapped in the capsule, the guest molecule undergoes the conformational conversion from chair form to twist-boat form slower than that under the free condition. The deformation of the capsule is favorable to maximize the attractive interactions between host and guest.

Letter

One-step Synthesis of ε-Caprolactam by the Liquid Phase Nitrosation of Cyclohexane over the Catalysts Containing CH3COO− or —COOH

MAO Li-qiu , CHEN Lei , WU Bo-hua , YIN Du-lin , YOU Kui-yi , LIU Ping-le , LUO He-an

2008, 24(2):  246-248.  doi:

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The nitrosation reaction of cyclohexane with nitrosyl sulfuric acid in the presence of fuming sulfuric acid in one-step to form ε-caprolactam has been studied using catalysts containing acetate or carboxy group in this work. To our delight, ε-caprolactam was for the first time directly obtained by such one-step catalytic process. While the conversion and selectivity are too low at this time to be commercially viable, this discovery establishes a potential new single step process for making ε-caprolactam from cyclohexane. A reaction mechanism is proposed.

Research Note

Fabrication and Optical Property of Cu₇S₄ Hollow Nanoparticles Formed Through Kirkendall Effect

WANG Chen-guang, XU Zhu-de , LIU Run

2008, 24(2):  249-250.  doi:

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Hollow nanoparticles can be synthesized through a mechanism analogous to the Kirkendall effect in aqueous solution. Cu₂O nanoparticles are first prepared. When the suspension of Cu₂O nanoparticles melt with Na₂S solution, Cu₇S₄ Hollow Nanoparticles are produced at room temperarure. Their crystal structures are different, but their size and morphology are similar. In addition, the UV-vis absorption peaks are not the same and the red-shift is obvious. This method is very simple and easy to produce hollow structures.