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Table of Content

    10 April 2015, Volume 36 Issue 4
    Cover and Content of Chemical Journal of Chinese Universities Vol.36 No.4(2015)
    2015, 36(4):  0-0. 
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    Review
    Perovskite Solar Cells: Work Mechanism and Major Factors Affecting Their Performances
    QIAN Liu, DING Liming
    2015, 36(4):  595-607.  doi:10.7503/cjcu20140927
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    Hybrid organic-inorganic perovskites were first introduced to photovoltaic community in 2009. In subsequent years, the power conversion efficiency has increased from 3.8% to ~20%, leaving dye-sensitized solar cells and bulk-heterojunction solar cells far behind. “Perovskite” is a crystal possessing the same crystal structure as calcium titanate, namely, ABX3. Perovskites have unique properties, like broad absorption spectra, high absorption coefficient, ambipolar charge transport, long exciton lifetime and very low binding energy of exciton. Currently, the architecture of perovskite solar cells has been simplified from meso-structured solar cells to planar-heterojunction solar cells, getting closer to the low-cost, high-efficiency target for practical application. Many innovative researches are pushing the application of this new photovoltaic material to the climax. This review summarizes the working mechanism of perovskite solar cells and expounds several key factors affecting device performance, i.e. components, crystallization and morphology, transport layers, electrode materials and planted bulk-heterojunction. However, we should note that perovskites have some drawbacks impeding its commercialization. Perovskites are sensitive to oxygen and water vapor, making the solar cells unstable in the ambient; it is challenging to prepare large films because the morphology of perovskite film is difficult to control; the use of the toxic metal, lead, will also undermine the credit earned by their outstanding photovoltaic performance. It is very important for us to understand those mechanism and factors affecting device performance, and to find approaches to deal with instability, toxicity, and bad morphology.

    Articles: Inorganic Chemistry
    Aqueous Synthesis of CdTe Quantum Dots via Ascorbic Acid Reducing Sodium Tellurite
    XIE Xian, YU Meihua, ZHANG Huiping, WANG Yilin
    2015, 36(4):  608-613.  doi:10.7503/cjcu20141079
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    Cd-SCH2COO- complex was formed under basic condition, then the ascorbic acid reacted with Na2TeO3 to form Te2- ions that combined with Cd-SCH2COO- complex to give CdTe nucleus. With the CdTe nucleus growing under refluxing, CdTe quantum dots(QDs) with different emission colors were formed at last. The influence of experimental conditions, including refluxing time, thioglycolic acid to cadmium molar ratio and sodium tellurite to cadmium molar ratio, on the luminescent properties of the obtained CdTe QDs were systematically investigated. Furthermore, the obtained QDs were characterized by X-ray powder diffraction(XRD) and transmission electron microscopy(TEM). Experimental results showed that the proposed method enables us to obtain zinc-blended CdTe QDs with high photoluminescence quantum yield(up to 27.1%). The growth time and the relative quantities of reactants impacted the optical properties of QDs.

    High-transparent and Flexible Au Nanofiber Films
    KONG Zhuang, LU Xianyong, ZHU Ying, JIANG Lei
    2015, 36(4):  614-618.  doi:10.7503/cjcu20141072
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    High-transparent and flexible Au nanofiber films were successfully fabricated by a combination of electrospinning technique and ion sputtering technology, in the presence of polyvinylpyrrolidone(PVP) nanofiber films as template. The as-prepared Au nanofiber films show typical interconnected nonwoven nanofiber networks, and the average diameters of Au nanofibers range from 291 nm to 322 nm. When sputtering time is 75 s, the average transmittance of the as-prepared Au nanofiber film in visible region is 92%, the reflectance in near infrared region is about 7%, and the resistivity is 2.9×10-3 Ω·cm. Importantly, after 500 cycles of bending, the as-prepared Au nanofiber films show no obvious electrical degradation. The Au nanofiber films with transparent and near-IR reflective properties may provide promising applications for flexible liquid crystal displays, solar cells and flexible and transparent functional electronics.

    Preparation and Characterization of Composites of Amine-functionalized Carbon Dots and Zinc Phthalocyaine
    DING Yanli, HU Shengliang, CHANG Qing
    2015, 36(4):  619-624.  doi:10.7503/cjcu20140930
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    Amine-functionalized carbon dots(N-CDs) and zinc phthalocyaine(PcZn) were combined by electrostatic bonding under the mechanical stirring, resulting in a new composite, i.e. N-CDs/PcZn. The photoinduced excited electron transfer via the interface between N-CDs and PcZn was determined through fluorescence spectra, UV-Vis absorption spectra, infrared spectra and cyclic voltammetry. The excited electrons of N-CDS were transfered onto the PcZn molecules and then relaxed by radiative recombination, causing the enhanced fluorescence emission of PcZn. On the other hand, the separation of electron-hole pair on N-CDs was realized and thus limited the possibility of radiative combination on N-CDs. Therefore, the composite of N-CDs/PcZn showed a high photocatalytic activity. Moreover, the stability and the photon conversion ability of N-CDs/PcZn composites depended on the reaction temperature. The experimental results suggest that room temperature is the optimum to obtain composite with good performance.

    Analytical Chemistry
    Novel Label-free Assay of Telomerase Based on DNAzyme
    FAN Hongliang, ZHANG Tao, JIN Wei, JIN Qinhan
    2015, 36(4):  625-630.  doi:10.7503/cjcu20141048
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    A novel method for telomerase detection based on DNAzyme and toehold-mediated strand displacement was developed. Optimal designing of a hairpin probe ensured efficient inhibition of DNAzyme activity by preventing it from forming the G-quadruplex structure. After the substrate TS was elongated by telomerase, the original hairpin structure could be destroyed through toehold-mediated strand displacement, so that the free DNAzyme was released, which catalyzed the oxidation of ABTS2- to generate an absorbance increase at 415 nm. The results indicated that the proposed method could detect the telomerase as low as 500 Hela cells equi-valent. Besides, this method is simple and requires no fluorescence labeling or complicated surface modification, and thus is expected to have a wide use in routine telomerase analysis of tumor cells.

    Preparation of Open Tubular Capillary Electrochromatography Column with Nano-chitosan Coating and Its Application for Basic Proteins Analyzing
    ZHANG Huanhuan, CHEN Jiyun, ZHOU Sunying
    2015, 36(4):  631-637.  doi:10.7503/cjcu20140978
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    Nano-chitosan particles(N-CS) prepared by ionic crosslinking technology were coated onto the inner wall of fused silica capillary via electrostatic adsorption to get a nano-chitosan coating capillary column. N-CS particles were successfully coated on the inner wall of the capillary as hillocks observed by field emission scanning electron microscopy. The electroosmotic flow(EOF) was tested in buffer at different pH values and compared to an uncoated capillary. The result showed that it was definitely inhibited after modification and reversed when pH<4.7. It was also found that EOF RSD of the prepared column was less than 6% in different acidity buffer and RSD of intra-day, inter-day and column to column were 1.46%, 4.64% and 14.4%, respectively. Those results indicated that the stability of N-CS coated column was good. The chromatographic behavior of the coated column was tested by separating three neutral analytes namely toluene, phenol and thiourea, the eluotropic sequence was consistent with their polarity, which indicated the nano-chitosan coatings played the role of hydrophilic stationary phase. Three basic proteins including lysosomes, cytochrome C and ribonuclease A were successfully separated with the resulting column, and their column efficiency were 39481, 42610 and 245373 Plate/m, respectively. The results showed that the adsorption between basic proteins and fused silica capillary is prevented effectively in the N-CS coated capillary.

    Novel Method Based on Colloidal Gold for Detection of Oligonucleotide Aptamer with Protein Interacting
    LIU Zhongcheng, ZHAO Lijian, LIU Lipeng, ZHANG Yanfen, WANG Nannan, CHEN Yao, WANG Xianghuan
    2015, 36(4):  638-645.  doi:10.7503/cjcu20140951
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    A novel method was developed for assaying affinity of aptamer with target protein and detecting the protein, which was based on the specific recognition of aptamers toward targets and high sensitivity of colloidal gold colorimetric. Oligonucleotide aptamer can protect colloid gold from coagulation in high salt conditions. When the aptamer bound to the target protein, the naked gold nanoparticles aggregated and the color of the solution changed. Then the affinity of target protein with aptamer and the concentration of target protein could be detected by monitoring A520 value. The best detection system was established, while the principal influence factors, such as the amount of aptamer and target protein, incubation time, competitive reaction time and the concentration of sodium chloride, were optimized.

    Dicyanostilbene-derived Two-photon Fluorescence Probe for Free Zinc Ions in Live Cells and Living Tissues
    HUANG Chibao, LIANG Xing, ZENG Qihua, CHEN Huashi, ZENG Boping, YI Daosheng, CHEN Xiaoyuan
    2015, 36(4):  646-653.  doi:10.7503/cjcu20140891
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    A novel two-photon fluorescence probe for Zn2+ derived from dicyanostilbene as a two-photon fluorophore and 4-(pyridine-2-ylmethyl)piperazine as a novel Zn2+ ligand was developed, and its structure was characterized by 1H NMR, IR and elemental analysis. By UV-Vis absorption and absorption-titration experiments, one- and two-photon excited fluorescence experiments in femtosecond pulses, as well as cell-imaging and tissue-imaging experiments, the probe showed a 72.5-fold fluorescence enhancement in response to Zn2+, a large two-photon action cross-section(580 GM), a noncytotoxic effect, and pH insensitivity in the biolo-gically relevant range, with a dissociation constant(KdTP) of (0.52±0.01) μmol/L. The probe could detect free Zn2+ ions selectively in live cells for about 1500 s and in living tissues at a depth of 80—150 μm without interference from other metal ions or membrane-bound probes.

    Organic Chemistry
    Excited-state Proton Transfer of 2-(2-Hydroxyphenyl)benzothiazole in the Confined Nanocavity
    XIANG Junfeng, YI Pinggui, YU Xianyong, CHEN Jian, HAO Yanlei, REN Zhiyong
    2015, 36(4):  654-659.  doi:10.7503/cjcu20141071
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    Proton transfer as one of the basic reaction exists in a large variety of chemical and biochemical process. And the organic molecules that exist the proton transfer process offten existence potential applications in biological and chemical industry. In this work, the supramolecular interaction of 2-(2-hydroxyphenyl)benzothiazole(HBT) with different concentrations cucurbit[7]uril(CB7) and its influences on the exited state intramolecular proton transfer(ESIPT) of HBT were studied with stead-state and transient fluorescence spectra in the different solvents. Furthermore, the inclusion ratio of CB7 and HBT were obtained according to Benesi-Hildebrand equation based on the fluorescence data. The results show that the stoichiometric ratio 1:1 host-guest complex of CB7 with HBT is formed in the N,N-dimethyeformamide(DMF) or dichloromethane solution, and the proton transfer of HBT is very sensitive to solvent. When the concentration of CB7 was increased, the fluorescence lifetime and quantum yield of HBT were decreased and increased respectively. The phenolic oxygen negative ion was formed in DMF, and the ESIPT of HBT was decreased in dichloromethane. The quantum chemical calculations show that CB7 can form the 1:1 HBT@CB7 complexes for the enol or keto tautomer of HBT.

    Synthesis of 3,5-Disubstituted Isoxazolines Mediated by Catalytic Alkyl Iodide
    FANG Yingguo, ZHU Min
    2015, 36(4):  660-664.  doi:10.7503/cjcu20141016
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    A new method for the preparation of 3,5-disubstituted isoxazolines using a catalytic amount of 1-iodopropane was developed and the optimization of the reaction conditions was obtained. The possible mechanism for the cycloaddition was suggested as followed: 1-iodopropane was first oxidized by oxone into the hypervalent iodine intermediate, then it decomposed at once to form hypoiodous acid, the in situ generated hypoiodous acid reacted with oxime and alkene, and after an elimination of HI, the reaction provided the desired isoxazoline. The new method has some advantages such as mild reaction conditions, simple procedure and good yields.

    Synthesis and Characterization of Task-specific Ionic Liquids with Alkyl Phosphate Cations and for U(Ⅵ) Extraction
    LI Hongyu, WANG Bo, LIU Shuming
    2015, 36(4):  665-671.  doi:10.7503/cjcu20140991
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    Three task-specific ionic liquids with tributyl phosphates(TBP) functional group covalently tethered to the cationic part, [Phos-C3-MIM][PF6], [Phos-C3-MIM][NTf2] and [Phos-C3-Pyr][NTf2], were synthesized. Their structures were confirmed by FTIR, 1H NMR and element analysis. Physical properties, such as phase transition temperatures, thermal stability, density and viscosity were also studied. The results of extraction perfermance as a single component, in the specific task of U(Ⅵ) extraction in nitric acid medium showed that they could be efficiently used to extract U(Ⅵ) in nitric acid medium at room temperature. The distribution ratio D(U) and the extraction efficience E could be achieved more than 10 and 90%, respectively, especially in high acidity environment.

    Design, Synthesis and Biological Activity of Novel Sulfonylurea Derivatives Containing Phenyl-substituted Pyrimidine Moiety
    CHEN Wei, WEI Wei, ZHOU Sha, LI Yonghong, ZHANG Xiao, TONG Jun, LI Yuxin, LI Zhengming
    2015, 36(4):  672-681.  doi:10.7503/cjcu20140955
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    Acetolactate synthase(ALS) has been regarded as an attractive target for fungicide and herbicide discovery. Furthermore, sulfonylurea(SU) as one of the most active ALS inhibitors were used as herbicides in crops protect. In order to discuss the multi-biological activity of SU, two series of novel SU derivatives containing phenyl-substituted pyrimidine moiety were designed, synthesized and their antifungal activity and herbicidal activity were evaluated. The bioassay results indicated that some title compounds showed excellent antifungal activity against Physalospora piricola and Rhizoctonia cerealis in vitro at the dosage of 50 mg/L. Particularly, compound 9f exhibited more than 65% inhibitory activity against five phytopathogens. On the basis of advanced screening test, the EC50 value of compound 8f against P. piricola was 8.63 mg/L, which was a little higher than Chlorothalonil(EC50=7.33 mg/L), the EC50 value of compounds 8k(5.48 mg/L) and 9k(6.09 mg/L) against R. cerealis were similar to Chlorothalonil(EC50=4.26 mg/L). In addtion, the title compounds showed favorable pre-emergence treatment herbicidal activity against Brassica napus and Amaranthus retroflexus at the dosage of 75 g/ha. For example, compounds 8d and 9d showed 86% and 73% inhibition activity respectively against Brassica napus; compound 9h exhibited 100% herbicidal activity against Amaranthus retroflexus, which was better than that of Chlorsulfuron(96%). The results provided useful information for designing new SU with highly fungicidal activity and herbicidal activity.

    Homologous Modeling of Transketolase AtTKL1 and Its Combination with α-Terthienyl in Arabidopsis Thaliana
    ZHAO Bin, HUO Jingqian, XING Jihong, QI Meng, ZHANG Jinlin, DONG Jingao
    2015, 36(4):  682-686.  doi:10.7503/cjcu20140934
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    Transketolase is the key enzyme of photosynthesis pathways. It is of great importance for herbicide seeking through new herbicidal substance targeting transketolase. In this study, homologous protein of transketolase was obtained through Modeler and optimized using Amber12, its binding sites of pivotal amino acids were identified with bioinformatics tools. Interaction between AtTKL1 and α-terthienyl finally got verified by spectroscopy and enzyme activity analysis. The three dimensional frame model of transketolase protein AtTKL1 in Arabidopsis thaliana was homologically modeled according to Maize transketolase protein 1ITZ, revised by dynamic molecular methods. With bioinformatics tools, the sites in AtTKL1 were determined, His143, Gly234, Asn263, Arg434, Ser461, Gln488, Phe515, His539, Asp547and Arg598 for binding, His103 and His340 for catalysis. The molecular docking of AtTKL1 and α-terthienyl was performed by computer simulation, and the results confirmed the perfect match of α-terthienyl with active cleavage of AtTKL1. The binding sites His143 and Gly234, and the catalytic sites His103 and His340 were the responsible binding sites of α-terthienyl. Prokaryotic expression of the protein and fluorescence quenching spectroscopy have verified the combination of α-terthienyl and AtTKL1. The reduction on the activity of transketolase treatmented with α-terthienyl gave a further confirmation about the interaction between AtTKL1 and α-terthienyl. The results will contribute to exploiting new efficient and low toxic herbicides.

    Synthesis, Antifungal Activity and Structure-activity Relationship of -Fluorophenyl-2,3-dihydro-1,5-benzothiazepines Derivatives
    ZHANG Jing, MU Boshuai, WU Meng, BIAN Yanqing, LI Yuan
    2015, 36(4):  687-697.  doi:10.7503/cjcu20140875
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    Twenty-six 4-fluoropheny-2,3-dihydro-l,5-benzothiazepine derivatives 2a—2z were synthesized and characterized by 1H NMR, 13C NMR, IR and high resolution mass spectrum(HRMS). The antifungal activities of those compounds were screened using the disk diffusion method against C. albicans and C. neoformans. The results showed that benzothiazepines 2a—2f had high antifungal activities against C. neoformans, while all of the benzothiazepines 2a—2z were almost inactive against C. albicans. Furthermore, the 1,5-benzothiazepines 2a—2f, which had high antifungal activities, were subjected to further pharmacological evaluation, including minimum inhibitory concentration(MIC, MIC80) and minimum fungicidal concentration(MFC) against C. neoformans. The results revealed that the MIC and MFC values for the above compounds were much lower than those of fluconazole. In order to study the structural features responsible for the antifungal activity of compounds 2a—2f, four series of analogues 3a—3f, 4a—4f, 5a—5f and 6a—6c were synthesized and tested for their antifungal activities against C. neoformans. The results suggested that the sulfur atoms, C=N structure on the seven-membered ring and the methoxycarbonyl/ethoxycarbonyl group at the 2 position are essential for antifungal activity.

    Application of L-2-Haloacid Dehalogenase from Thermophilic Archaea Sulfolobus Tokodaii in the Production of D-Lactic Acid
    XIE Guiqiu, PAN Dong, He Wenlong, GAO Gui, GAO Renjun
    2015, 36(4):  698-703.  doi:10.7503/cjcu20140739
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    Optical pure lactic acid is a useful chiral intermediate in the synthesis of chiral drugs and materials engineering. For the purpose of environmental-friendly and high stereoselectivity, enzymes were used to resolve racemic mixtures. In this study, we cloned and expressed L-2-haloacid dehalogenase(ST2570) from thermophilic Archaea Sulfolobus tokodaii in Escherichia coli BL21(DE3). The recombinant enzyme was purified to a single band using heat treatment and Ni2+-NTA affinity chromatography. The optimum temperature and pH value of ST2570 were 70 ℃ and 9.5, respectively. The specific activity of purified ST2570 for the hydrolysis of 2-chloropropionic acid was 2963.33 U/mg. For the high enatioselectivity of ST2570, only L-2-chloropropionic acid can be hydrolyzed to produce D-lactic acid during the reaction. With the optimization, the best conditions to produce D-lactic acid were pH of 9.5, temperature of 60 ℃, 3 mol/L of buffer, 0.5 mol/L of 2-chloropropionic acid and 3×104 U/L of ST2570.

    Effects of Chemical Modification with Chitooligosaccharides on Catalytic Activity and Enzymological Properties of Laccase from Trametes versicolor
    LI Chunyi, HUANG Zhuolie, WANG Chunxiao
    2015, 36(4):  704-712.  doi:10.7503/cjcu20140771
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    Chemical modification is an important pathway to transform the catalytic activity and enzymological properties of enzymes. In order to improve the catalytic activity and enzymological stability of laccase from Trametes versicolor(EC 1.10.3.2, TvL), the enzyme was purified by DEAE 52 weak anion exchange resin chromatography. The pure enzyme was activated by NaIO4. The activated enzyme was chemically modified with chitooligosaccharides(COS, average relative molecular weight 5000). The optimal modification conditions by single factor and orthogonal experiments were: temperature 5 ℃, pH=4.0, 100 mg NaIO4, 20 mg COS. Under these conditions the activity of modified enzyme(COS-TvL, 456.00 U/mg) was 145.04% of that of unmodified enzyme(TvL, 314.39 U/mg). The results of SDS-PAGE experiments indicated that the relative molecular weights of 3 polypeptides of TvL were 58100, 45200 and 21600, respectively. But the relative molecular weights of 3 polypeptides of COS-TvL were 62900, 53300 and 39700, respectively. This meant that the modification experiments were successful. The amino modification rates changed from 0 of TvL to 30.7% of COS-TvL. The optimal pH values of TvL and COS-TvL were 4.0 and 3.5—4.0, respectively. The optimal temperatures of TvL and COS-TvL were 40 and 45 ℃, respectively. The results of kinetic study indicated that Km and vmax of TvL were 9.929 mmol/L and 714.29 mmol/(mg·min). But the Km and vmax of COS-TvL were 8.989 mmol/L and 1250 mmol/(mg·min), respectively. The infrared spectra, the ultraviolet absorption spectra, the ultraviolet differential spectra, and fluorescence emission spectra of TvL and COS-TvL were also studied and analyzed.

    Physical Chemistry
    Controllable Detemplation of Nanozeolites and Research of Molecular Diffusing Limitation
    GUO Xiao, LIN Shaoying, QIN Kai, ZHANG Yahong, TANG Yi
    2015, 36(4):  713-719.  doi:10.7503/cjcu20150001
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    Zeolites are microporous crystalline materials with large surface area and high hydrothermal stability, which have been widely applied in areas like petrochemical industry, fine chemistry and environmental protection. However, their small and long micropore channels result in larger diffusion resistance in catalytic reaction and consequent coke deposition and fast deactivation of catalysts. Here, β nanozeolites were hydrothermally synthesized under microwave irradiation, followed with a microwave-assisted Fenton-like oxidation step to rapidly and controllably remove the template of as-prepared β nanozeolites. Consequently, a series of β nanozeolites with different pore depths and available acid sites was obtained. Still, dehydration of fructose into 5-HMF(5-hydroxymethylfurfural) catalyzed by acid catalyst was used to study the influence of different pore depths and acid sites of β nanozeolites on their catalytic performances. It is found that diffusing limitation displays more important effects than those of the active sites numbers in the reactions catalyzed by microporous zeolites, which further implies the significance of diffusing limitation of reactants/products in catalytic reactions with microporous catalysts, and the necessity of preparing catalysts with hierarchical pores and short pore length, which will make favorable effects on the reaction results by both the influence of acid sites and micropore depths for as-prepared catalyst.

    Functionalized Graphene Oxide Supported Pd Nanoparticles Catalyzed Heck Coupling Reaction
    YIN Jie, DING Shunmin, ZENG Le, XIA Hui, CHEN Chao, ZHANG Ning
    2015, 36(4):  720-724.  doi:10.7503/cjcu20140997
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    Pd nanoparticles were immobilized on a graphene oxide(GO) functionalized by 3-(2-aminoethyl)-aminopropyl trimethoxysilane support. The catalyst was characterized by Fourier transform infrared(FTIR), X-ray diffraction, thermal analysis, elementary analysis, and transmission electron microscopy. The catalyst exhibited a superior catalytic performance in Heck coupling reaction, and was applicable to a wide range of substrates. Recycling experiments showed that the catalyst could be easily recovered by simple centrifugation and reused for up to three cycles without losing its activity.

    Preparation of Hierarchical Porous HZSM-5 and Its Application in Light Paraffin Aromatization
    ZHANG Ruizhen, WANG Cui, XING Pu, WEN Shaobo, WANG Jian, ZHAO Liangfu, LI Yuping
    2015, 36(4):  725-732.  doi:10.7503/cjcu20140987
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    The HZSM-5 molecular sieves were modified by 0.2 mol/L NaOH aqueous solution for 30, 120 and 300 min, respectively and the as-prepared catalysts were characterized by the X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy, ammonia temperature-programmed desorption(NH3-TPD) and Fourier transform infrared spectroscopy of adsorbed pyridine. The catalytic activity, stability and BTEX selectivity of alkali-treated HZSM-5 in the light paraffin aromatization were also investigated. The results showed that the degree of crystallization decreased and the mesopores were produced in the HZSM-5 molecular sieves with the increase of alkali-treatment time, and at the same time the acidic properties of HZSM-5 could also be tuned by alkali treatment, the Brönsted acid sites were decreased while the Lewis acid sites were increased with the increase of alkali modification time. Catalytic evaluation of light paraffin aromatization over modified HZSM-5 revealed that HZSM-5 treated by NaOH for 120 min exhibited the best aromatization activity, stability and BTEX selectivity due to its suitable pore structure and acidic distribution.

    Preparation and Characterizations of Zn-doped Li1.13Ni0.3-xMn0.57ZnxO2 Cathode Materials for Lithium Ion Batteries
    WANG Xue, YANG Lili, WANG Chunzhong, CHEN Gang, WEI Yingjin
    2015, 36(4):  733-738.  doi:10.7503/cjcu20140905
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    Zn-doped Li1.13Ni0.3-xMn0.57ZnxO2 samples were synthesized by co-precipitation method. X-ray diffraction shows that Zn doping decreases the Li+/Ni2+ cation mixing of the material, increases the structure stability and expands the lattice volume of the material which provides more space for lithium ion intercalation/de-intercalation. Electrochemical experiments show that Zn doping decreases the charge transfer resistance of the electrode, improves the reversibility of lithium intercalation and de-intercalation, thus the electrochemical properties of the material are improved. Especially, the Li1.13Ni0.29Mn0.57Zn0.01O2 material with Zn doping of x=0.01 shows the best electrochemical performance with the largest discharge capacity, best rate capability, excellent capacity retention and thermal stability.

    Influence of LiBOB on the Electrochemical Performance of Li1.15Ni0.68Mn1.32O4 Electrode
    JIANG Xue, SHI Nannan, ZHANG Ying, CHENG Kui, YE Ke, WANG Guiling, CAO Dianxue
    2015, 36(4):  739-744.  doi:10.7503/cjcu20140836
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    The influence of electrolyte additive lithium bis(oxalate)borate(LiBOB) on the electrochemistry performance of Li1.15Ni0.68Mn1.32O4 electrode was studied by means of galvanostatic charge-discharge. X-ray diffraction(XRD), Fourier transform infrared attenuated total reflectance(FTIR-ATR) spectroscopy, inductively coupled plasma-atomic emission spectrometry(ICP-AES), scanning electron microscopy(SEM) and electrochemical impedance spectroscopy(EIS) were used to investigate the influence. The results show that the cyclic performance of Li1.15Ni0.68Mn1.32O4 electrode is improved apparently by the addition of LiBOB, and the reason is that LiBOB may decompose during the charge-discharge process and the decomposition product further deposites on the surface of Li1.15Ni0.68Mn1.32O4 electrode, forming solid electrolyte interface(SEI) film, inhibiting the dissolution of Mn and keeping the crystal structure of Li1.15Ni0.68Mn1.32O4 stable, therefore, the cyclic performance of Li1.15Ni0.68Mn1.32O4 is improved.

    Controllable Synthesis and Performance of Micro-nano Structure MFe2O4(M=Zn, Co) in Lithium-ion Batteries
    YUE Hongyun, WANG Qiuxian, ZHANG Xue, HUA Shuang, MA Hua, YUE Dongyuan, YANG Shuting
    2015, 36(4):  745-750.  doi:10.7503/cjcu20140728
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    Micro-nano structure MFe2O4(M=Zn, Co) materials were synthesized directly by hydrothermal method. The structural and morphological properties of the samples were investigated by means of X-ray diffraction(XRD) and transmission electron microscopy(TEM). The electrochemical performance of MFe2O4(M=Zn, Co) was examined by galvanostatic charge-discharge test and electrochemical alternate current(AC) impedance technique. The results show that hollow sphere CoFe2O4 and ZnFe2O4 have a reversible capacity of 1180 and 655 mA·h/g after 50 cycles, which are higher than those of solid sphere materials. At the same time, the formation mechanism of different morphology was studied.

    Polymer Chemistry
    Effect of Anisotropic Photo-crosslinking on Liquid Crystal Alignment with Duplicated Surface-relief-gratings
    GUO Miaocai, HE Yaning, WANG Xiaogong
    2015, 36(4):  751-757.  doi:10.7503/cjcu20141141
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    Surface-relief-gratings with further photo-crosslinkable property were prepared by softlithography using photo-sensitive polyimide containing cinnamate groups as “ink”. The effect of anisotropic photo-crosslinking on the thermos-stability of gratings and the alignment of liquid crystal(LC) on gratings was studied. The thermos-stability of the photo-cured gratings was significantly increased. No shape deformation was observed for the gratings after treated at a temperature 31 ℃ above the glass transition temperature of the un-cured polyimide. Both the un-exposed and exposed gratings induced uniform LC alignment on their surfaces. By irradiation with linear polarized UV light perpendicular to the gratings grooves, the LC alignment was enhanced. By changing the polarized direction of the UV light and controlling the depths of gratings, the LC alignment direction on the gratings was adjusted. This study result shows that the photo-crosslinkable gratings can achieve better thermo-stability, better LC alignment and adjustable aligned direction to achieve multi-domain alignment. The above research can lead to further understanding of the LC alignment mechanism.

    Fabrication and Characterization of Alginate/Chitosan Polyelectrolyte Complex Elastic Scaffolds
    ZHANG Weijun, ZHANG Kunxi, LI Guifei, ZHANG Danqing, YIN Jingbo
    2015, 36(4):  758-764.  doi:10.7503/cjcu20141094
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    Elastic scaffolds composed of sodium alginate(SA) and chitosan(CS) were fabricated via electrostatic interaction between —COOH, —NH2 groups and phase separation technique. This study presented the influence of freezing temperature, solid content on pore size and molar ratio on mechanical strength, hydrophilicity, biodegradability and biocompatibility. The results showed that average pore size of alginate/chitosan scaffolds fabricated from 2%(mass fraction) solid content and at a freezing temperature of -24 ℃ was between 110 and 170 μm. High swelling ratio of more than 1400% showed the excellent hydrophilic performance of these scaffolds. Degradation of the alginate/chitosan scaffolds could be modified by varying the molar ratio(—COOH/—NH2). The mechanical strength of the scaffolds could be controlled by different molar ratios and solid contents. The scaffolds exhibited good elastic behavior and fatigue durability by cyclic mechanical test in wet state. In vitro culture of rabbit adipose-derived stem cells(rASCs) indicated that aggregated rASCs were formed in the scaffolds when the molar ratios were 2:1 and 1:1, while adherent rASCs were found in the scaffolds with molar ratio of 1:2. Hence cellular adhesion behavior can be regulated by varying scaffold component.

    Stability of a Novel Poly(amide-urea-imide) Composite Reverse Osmosis Membrane
    WU Lixiang, CAI Zhibin, CHEN Xiaolin, LIU Lifen, ZHU Lifang, GAO Congjie
    2015, 36(4):  765-771.  doi:10.7503/cjcu20141084
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    A novel poly(amide-urea-imide) composite reverse osmosis membrane was fabricated via two-step interfacial polymerization. First, 5-isocyanato-isophthaloyl chloride(ICIC) as a key functional monomer reacted with m-phenylenediamine(MPD) to prepare the initial substrate MPD-ICIC membrane by single interfacial polymerization technology. Then, the other key functional monomer N,N'-dimethyl-m-phenylenediamine(DMMPD) was polymerized with the remaining ICIC and acyl chlorine group(—COCl) or isocyanato group(—N=C=O) of the substrate membrane to obtain the new poly(amide-urea-imide) composite reverse osmosis membrane(MPD-ICIC@ICIC-DMMPD) after heat-curing and water rinse. The surface chemical structure of membrane active layer was analyzed by combination of attenuated total reflectance infrared and X-ray photoelectronic spectroscopy, and the separation performance of membrane was also measured. Then, the stability of the obtained membrane MPD-ICIC@ICIC-DMMPD was further analyzed microscopically by molecular dynamic simulation method.

    Preparation and Electromagnetic Wave-absorbing Properties of Micro-polyaniline/Fe3O4 Hollow Spheres
    LI Tao, ZHANG Long, CHEN Ying, GUO Yajun, DU Xueyan
    2015, 36(4):  772-780.  doi:10.7503/cjcu20141000
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    Doped polyaniline/Fe3O4(D-PANI/Fe3O4) with hollow spheres were prepared by the combination of interfacial polymerization and Pickering emulsion polymerization method with toluene as soft template, Fe3O4 nanoparticles as cosurfactant, sodium dodecyl benzene sulfonate(SDBS) as emulsifier, ammonium persulfate(APS) as oxidant, hydrochloric acid(HCl) as the doping agent. And as a comparison, the polyaniline/Fe3O4(PANI/Fe3O4) with hollow spheres were prepared without acid doping. The morphology, structure, integrant, magnetic and electrical properties of the composite material were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), thermogravimetric(TG), vibration sample magnetism(VSM) and the four-probe method, respectively. The results indicate that the D-PANI/Fe3O4 with hollow spheres structures were prepared successfully. The diameter of D-PANI/Fe3O4 hollow spheres was about 2.8 μm, the conducti-vity and saturation magnetization(Ms) of D-PANI/Fe3O4 hollow spheres were 2.75×10-2 S/cm and 54.26A·m2/kg, respectively.The quality of Fe3O4 nanoparticles accounted for about 28% of D-PANI/Fe3O4 hollow spheres. Electromagnetic properties and wave absorption performance of D-PANI/Fe3O4 hollow spheres and PANI/Fe3O4 hollow spheres were analyzed by vector network analyzer(VNA). The results showed that the best absorbing property and minimum reflection loss(RL) of D-PANI/Fe3O4 composites were -43.3 dB at 12.64 GHz with the matching thickness of 2 mm, and the wave absorption performance was superior to PANI/Fe3O4 composites.

    Preparation and Fuel Cell Performance of Carbonyl and Sulfone Groups Co-crosslinked Sulfonated Polyimide Proton Exchange Membranes
    CHEN Kangcheng, BAI Wenxin, ZHAO Zhiping, LIU Wenfang, YANG Zhi
    2015, 36(4):  781-787.  doi:10.7503/cjcu20140989
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    A series of six-membered ring type SPI PEMs was synthesized with 3,5-bis(4-aminophenoxy) benzoic acid(BAPBa). Carbonyl and sulfone co-crosslinked SPI PEMs were prepared by methanesulfonic acid/phosphorus pentoxide solution(PPMA). Their properties including proton conductivity, hydrolysis resistance, mechanical properties and fuel cell performance were investigated. The results showed that the crosslinking degree of carbonyl and sulfone co-crosslinked SPI PEMs increased, while the consumption of sulfonic acid group decreased, which kept the SPI PEMs maintaining high proton conductivity when compared to the sulfone groups crosslinked ones. For example, the proton conductivity of the carbonyl and sulfone co-crosslinked SPI PEM was 7.8 mS/cm at 50%RH, which increased by 28%. After aging in water at 130 ℃ for 500 h, elongation at break of the carbonyl and sulfone co-crosslinked SPI PEM was 18% and no obvious reduction in proton conductivity. Fuel cell performance showed that, the maximum power output of the carbonyl and sulfone co-crosslinked SPI PEM reached 0.85 W/cm2, which was 1.3 times higher than that of sulfone crosslinked one.

    Rheological Properties of Two-component Silicon Rubber During Cross-linking by Addition Reaction
    ZHANG Huanhuan, XU Donghua, GUAN Dongbo, YAO Weiguo, SHI Tongfei
    2015, 36(4):  788-793.  doi:10.7503/cjcu20140857
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    The kinetic for two-component silicon rubber formed by addition reaction was studied by the rheological method. The influence of reaction temperature on reaction rate was also explored. The Oscillatory frequency has no influence on the study for the cross-linking process of two-component silicon rubber with rheological method. As the addition reaction going on, the cross-linking degree becomes bigger and the properties of system change from liquid properties dominate to solid properties dominate. With reaction temperature increasing, the cross-linking rate of silicon rubber quickens and less time is needed to finish the cross-linking reaction. Based on the relation between cross-linking velocity and the reaction temperature, the apparent activation energy of system can be obtained. Rheological method is suitable for studying the silicon rubber cross-linking process.

    Synthesis, Characterization of Methoxyl-bridged Aluminium-lithium Heterobimetallic Complex and Catalysis for the Ring-opening Polymerization of ε-Caprolactone
    WANG Lei, YANG Li, GAO Chengyong
    2015, 36(4):  794-798.  doi:10.7503/cjcu20140849
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    The methoxyl-bridged aluminium-lithium heterobimetallic complex [(L)Al(μ2-OMe)Li(THF)3]2(1) was synthesized and structurally characterized. Reaction of 2,6-bis(3,5-bis-t-butyl-2-hydroxybenzyl)-4-t-butyl phenol(H3-L) with n-BuLi and Al(CH3)3 in a molar of ratio 1:1:1 in THF provides methyl-aluminium-lithium phenoxide [(L)Al(CH3)Li]. Oxidation of the phenoxide by O2 in air gives target product 1 in quantitative yield. Catalysis by complex 1 for ring-opening of ε-caprolactone(ε-CL) was studied. Experimental results indicate that complex 1 could catalyze ε-CL with high conversion and narrow polydispersity even in an air atmosphere.

    Effect of Modified Sodium Alginate Aggregation Behavior on Electrospun Nanofiber Morphology
    GAO Pengbo, FENG Yuhong, LI Jiacheng, YAN Huiqiong, HUANG Junhao, WU Tiantian, HUANG Wenhong
    2015, 36(4):  799-807.  doi:10.7503/cjcu20140842
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    Using the potassium persulfate(KPS) as an initiator, through modified reaction of diacetone acrylamide(DAA) and sodium alginate(SA), the amphiphilic SA-PDAA block copolymer was synthesized. By electrospinning the mixture of SA-PDAA and polyvinyl alcohol(PVA) solution, SA-PDAA/PVA electrospun fibers were prepared. The structure and properties of SA-PDAA were characterized by means of Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC) and fluorescence spectrum. Furthermore. The physical properties of SA-PDAA spinning solution were determined by viscometer, surface tensiometer and electrical conductivity meter, the morphology of SA-PDAAA/PVA electrospun fibers were determined by scanning electron microscopy(SEM). And the drug release studies of SA-PDAAA/PVA electrospun fibers were also investigated. Experimental results showed that DAA had successfully grafted onto the sodium alginate molecular chains. The critical aggregation concentration measured by fluorescence spectrum was reduced to 0.072 g/L, which demonstrated the good amphipathy of SA-PDAA. The morphology of SA-PDAA/PVA electrospun fiber exhibited more uniform size. The drug release properties show that SA-PDAA can effectively slow the drug release rate, thus improving the retarded releasing characteristics of SA-PDAA/PVA electrospun fibers.

    Interfacial Interaction Mechanism of Etherified PBS and CMC Liquid Composites
    ZHANG Min, XU Xiaoling, SONG Jiqing, HE Wenqing
    2015, 36(4):  808-814.  doi:10.7503/cjcu20140792
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    Poly(butylene succinate)(PBS) was etherified by polyethylene glycol(PEG), and blended with carboxymethylcellulose(CMC). A novel liquid composite(PEG/PBS)-CMC was successfully prepared in water solution. The interaction mechanism of (PEG/PBS)-CMC composite was investigated by molecular simulation. The results showed that the desired structure of PEG/PBS with good hydrophilicity was achieved. Molecular simulation displayed that the polarity and flexibility of PEG/PBS was enhanced by introducing PEG to PBS. The interactions of (PEG/PBS)-CMC were hydrogen bonding, van der Waals, hydrophobic bond and adsorption. This results were explained by the deviation of absorption peak frequency on functional groups such as —OH, —OCO—, —COOH and —C—O—C— in Fourier transform infrared(FTIR) and the binding energy transfer of C and O element in X-ray photoelectron spectroseopy(XPS). Non-covalent interaction existed between composites displayed in polarizing optical microscope(POM) and X-ray diffraction(XRD). The closely integrated interface of (PEG/PBS)-CMC in scanning electron microscope(SEM) showed that the binding forces and the compatibility were enhanced after etherification modification.