Chem. J. Chinese Universities

Cover and Content of Chemical Journal of Chinese Universities Vol.37 No.11(2016)

2016, 37(11): 0-0.

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Induced Growth of Micro/nano ZnO Powder via Glu-BF₄Ionic Liquid Aqueous Solution^†

TONG Laga, REN Guangsheng, DANG Xiaofeng, LIN Shijing, RONG Hua

2016, 37(11): 1939-1946. doi:10.7503/cjcu20160471

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In this study, pompon-like micro/nano ZnO powders have been synthesized via microwave assisted heating of the precursors which were prepared with Zn(OAc)₂·2H₂O and NaOH(molar ratio 1∶6) as reactants and Glu-BF₄ ionic liquid aqueous solution as reaction medium at room temperature. The products were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), specific surface area analysis, energy spectroscopy(EDS), Raman spectroscopy and transmission electron microscopy(TEM), respectively. The results show that the prepared product has hexagonal wurtzite structure with high purity, the average particle diameter is 20.4 nm, the size of pompon-like structure is about 1.6—3.0 μm and the BET surface area is 28.3 m²/g. When the concentration of the reactant was fixed, micro/nano ZnO with similar morphologies was synthesized using different dosages of ionic liquid, and with increase of the ionic liquid dosage, the size distribution of particles became more uniform. When the ionic liquid concentration was fixed, the morphology of product changed gradually with the decrease of the reactant concentration. Under the induction of Glu-BF₄ ionic liquid, ZnO crystal grains firstly formed irregular nanosheets, then those nanosheets further aggregated to form the pompon-like powder in certain range of reactants concentration. Only the core part of the pompon-like powder was synthesized when the reactants concentration was relatively lower, while the nano-array morphologies were generated at higher reactant concentrations. In addition, the growth mechanism of micro/nano ZnO powder induced by Glu-BF₄ ionic liquid aqueous solution under strong alkaline condition was discussed via morphology change tendency of nano ZnO powder under different conditions.

Preparation and Characterization of Amino-functionalized Magnetic Graphite Nanosheet Nanocomposites^†

XING Dan, MA Yingxia, RUAN Yongxin, DU Xueyan

2016, 37(11): 1947-1952. doi:10.7503/cjcu20160497

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Amino-functionalized magnetic graphite nanosheet(NH₂-GNS/Fe₃O₄) nanocomposites were prepared by one-pot solvothermal method with GNS as carrier, FeCl₃·6H₂O as precursor, ethylenediamine as modifier and reductant, ethanediol as surfactant and reductant and sodium acetate as stabilizer. The as-prepared sample was characterized by transmission electron microscope(TEM), X-ray diffractometer(XRD), Fourier transform infrared spectrometer(FTIR) and vibrating sample magnetometer(VSM). The adsorption property of the NH₂-GNS/Fe₃O₄ nanocomposites for Ag(Ⅰ) in aqueous solution was studied. The results indicate that the NH₂-GNS/Fe₃O₄ nanocomposites were successfully prepared, the magnetic property of NH₂-GNS/Fe₃O₄ nanocomposites could meet the requirement of the solid-liquid separation. The NH₂-GNS/Fe₃O₄ nanocomposites had adsorption property for Ag(Ⅰ) in aqueous solution, moreover, Ag(Ⅰ) was reduced into silver in the process of adsorption. The adsorption process of NH₂-GNS/Fe₃O₄ nanocomposites for Ag(Ⅰ) in aqueous solution was the monolayer adsorption on the homogeneous surface.

Preparation of Ce-Doped Graphitic Carbon Nitride with Enhanced Visible-light Photocatalytic Activity^†

LIANG Ruiyu, XU Dongdong, ZHA Wenying, QI Jizhen, HUANG Langhuan

2016, 37(11): 1953-1959. doi:10.7503/cjcu20160273

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Graphite carbon nitride(g-C₃N₄) doped with different amounts of Ce were prepared with Ce(NO₃)₃ and melamine as raw materials. The as-prepared samples were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR), ultraviolet visible diffuse reflectance spectroscopy(DRS), photoluminescence(PL) and X-ray photoelectron spectroscopy(XPS). The results showed that the Ce doped into g-C₃N₄ exists in the form of Ce³⁺ and Ce⁴⁺. Ce dopant could decrease the grain size, increase the electron/hole separation rate and affect the energy band structure. Because of these properties, the obtained Ce doped g-C₃N₄ exhibited an enhanced visible light photocatalytic activity toward degradation of methylene blue when compared with pure g-C₃N₄. In particular, the 0.10-Ce-C₃N₄ sample exhibited the highest activity. The degradation rate of MB over 0.10-Ce-C₃N₄ was 98.51% in 80 min. The rate constant for 0.10-Ce-C₃N₄ reached 0.0506 min^-1, which was 4.9 times that of pure g-C₃N₄. 0.10-Ce-C₃N₄ also displayed good stability with slight decrease of photocatalytic efficiency after five times recycles. A possible mechanism of the improvement of visible light photocatalytic activity was proposed.

Optical Resolution of D,L-Phenylglycine and Chiral Separation Mechanism Using an Enantioselective Membrane of Vancomycin^†

YUAN Liming, SU Yingqiu, DUAN Aihong, ZHENG Ying, AI Ping, CHEN Xuexian

2016, 37(11): 1960-1965. doi:10.7503/cjcu20160460

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Using vancomycin and 1,6-diisocyanatohexane as the monomers, an enantioselective composite membrane was prepared by interfacial polymerization on a polysulfone support and was analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy. The composite membrane was used for enantioseparation of D,L-phenylglycine which is an indispensable reagent in the syntheses of penicillins and cephalosporins. By optimizing the molar ratio of vancomycin and 1,6-diisocyanatohexane, the time of polymerization and the feed concentration of the racemate, an enantiomeric excess[e.e.(%)] of over 70% D-phenylglycine could be obtained. Comparing the membrane adsorption, solid extraction, membrane chromatography, dialysis and ultrafiltration of vancomycin optical resolution membrane, the L-phenylglycine was prior adsorbed, while, the D-phenylglycine was first permeated the membrane. Based on the association characteristic of racemate of D,L-phenylglycine, we suggested, in the first time, that the enantioseparation mechanism of membrane was “adsorption-association-diffusion”.

Calix[4]crown-based 1,3,4-Oxadiazoles as Fluorescent Chemosensors:Synthesis and Ion Recognition^†

XIE Dihuan, SUN Chun, WANG Xiaojing, HAN Jie

2016, 37(11): 1966-1971. doi:10.7503/cjcu20160542

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Two fluorescent chemosensors, 1a and 1b, were synthesized by appending 2-phenyl-5-(2-pyridyl)-1,3,4-oxadiazole or 2,5-diphenyl-1,3,4-oxadiazole moieties on a calix[4]crown skeleton, respectively. Their molecular structures were characterized by proton and carbon nuclear magnetic resonance spectroscopy(¹H NMR and ¹³C NMR) and high resolution mass spectroscopy(HRMS). The recognition behaviors of probes 1a and 1b in CH₂Cl₂ solution to alkali metal ions(Na⁺, K⁺, Cs⁺), alkaline earth metal ions(Mg²⁺, Ca²⁺) and transition metal ions(Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺) were investigated by UV-Vis spectrum and fluorescence spectrum. The results showed that Na⁺enhanced the fluorescence intensity of probe 1a significantly, while K⁺ and Cs⁺ only resulted in negligible changes in the fluorescence. In contrast, Ca²⁺and all the transition metal ions may quench the fluorescence greatly due to the photo-induced electron transfer mechanism. The recognition behaviors of probe 1b to alkali metal ions are similar to those of probe 1a, and com-plexation between probe 1b and the transition metal ions is weaker than that of probe 1a and the transition metal ions. The complexation has been investigated by means of ¹H NMR titration.

Absolute Configuration Determination of One New Compound Trichoderol A from Trichoderma sp. Fungus^†

XU Lanlan, ZHAO Qiqi, YU He, WANG Jingchen, WANG Huijun, YANG Qin, ZHU Huajie, LI Yan

2016, 37(11): 1972-1976. doi:10.7503/cjcu20160499

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One new compound, trichoderol A(1), was isolated from cultures of the fungus Trichoderma sp. The structure of compound 1 was established by means of NMR and mass spectrometry. The absolute configuration(AC) was determined by means of comparing experimental electronic circular dichroism(ECD) and optical rotation(OR) of compound 1 with the calculated ECD and OR data of compound 1 using quantum methods, also using matrix model. Compound 1 was evaluated for antibacterial activities against three species of pathogenic bacteria, and the results showed that compound 1 had weak antibacterial activities(MIC=25 μmol/L).

Design, Synthesis and Biological Activity of Novel Aphid Alarm Pheromone Analogues Containing Isonicotinic Acid^†

QIN Yaoguo, ZHANG Jingpeng, SONG Dunlun, DUAN Hongxia, LING Yun, JIANG Biaobiao, WANG Di, YANG Xinling

2016, 37(11): 1977-1986. doi:10.7503/cjcu20160434

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A series of new aphid alarm pheromone[(E)-β-farnesene, EBF] analogues containing isonicotinic acid was designed based on the principles of connecting sub-structure and bioisosterism. With EBF as a lead compound, 20 EBF analogues were prepared via four steps starting from geraniol. Their structures were confirmed by ¹H NMR, ¹³C NMR, IR and HRMS. The preliminary bioassay suggested that all the analogues showed repellent and aphicidal activities against Myzus persicae(Sulzer). Among them, compounds 7d, 8f and 8n showed good repellent activity with the repellent rate of 62.6%, 62.0% and 61.0% respectively; and the analogues 8a, 8b and 8d exhibited better aphicidal mortality of 73.6%, 81.1% and 70.2% than lead EBF. The primary structure-activity relationship(SAR) analysis indicated that introducing of ester group was favorable to repellent activity while introducing amide was conducive to aphicidal activity. Moreover, N-substituted carbon chain length, number of branched chain as well as aromaticity played roles in repellent activity. This study provides useful clues for further development of novel aphid control agent.

Chemical Synthesis of K33 Acetylated SUMO Protein^†

WANG Yehai, KONG Yifu, CHEN Chenchen, LI Yiming

2016, 37(11): 1987-1992. doi:10.7503/cjcu20160417

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Sumoylated protein was found to reduce the protein binding force with the SUMO-interaction motif(SIM) of effector protein when K33 of SUMO was acetylated. To further study the structures and mechanism, a large amount of uniformity acetylated SUMO protein was greatly needed. In this work, SUMO protein and K33 acetylated SUMO protein was efficiently obtained using high temperature assisted solid-phase peptide synthesis(SPPS) technology combined with peptide hydrazide ligation. SUMO and K33 acetylated SUMO was identified with corrected molecular weight by the SDS-PAGE. It was also confirmed that the chemically synthe-tic protein and biologically expressed SUMO2 own similar homogeneity and secondary structure by the CD analysis. These results provided a foundation for the follow-up study of K33 acetylated SUMO protein.

Absolute Configuration Determination for Natural Products(Ⅱ)^†-Absolute Configuration Determination for Alkaloids by Comparing Computed Optical Rotations, ¹³C NMR and ¹H NMR with the Experimental Results

HU Dongbao, ZHOU Beidou

2016, 37(11): 1993-1998. doi:10.7503/cjcu20160228

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In order to study the absolute configuration of natural product, some compounds of undetermined absolute configuration were screened, the optical rotation(OR), ¹³C NMR and ¹H NMR data were gotten by density functional theory(DFT) at different computational levels. The computational results matched the experimental results well. The results show that the PCM solvent model could improve the accuracy of computed optical rotation for the rigid alkaloid molecules but not be applicable to flexible ones. Therefore, the chira-lity centers of these alkaloids were determined.

Fabrication of Soy Protein Isolate-soluble Soy Polysaccharide Core-shell Nanogels via Maillard Reaction and Self-assembly^†

FENG Jilu, QI Junru, LIU Qianru

2016, 37(11): 1999-2005. doi:10.7503/cjcu20160364

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A “two-step” method, which involved Maillard reaction in macromolecular crowding environment and self-assembly approach, has been adopted to fabricate the novel and safe core-shell nanogels. First, amphiphilic graft copolymers were synthesized by soluble soy polysaccharide(SSPS) covalently attaching to soy protein isolate(SPI) via Maillard wet-heating reaction. Second, the resultant conjugates(SSC) were induced by both hydrophobic and electrostatic interaction to self-assemble soy protein isolate-soluble soy polysaccharide(SPI-SSPS) nanogels. Microscopic technology indicated that the SPI-SSPS nanogels were well-separated and spherical in shape with obvious core-shell structures: the hydrophilic soy polysaccharide constituted the shell and the cross-linked soy protein constituted the core. Spectroscopy investigation revealed that the tertiary structure of protein in nanogels was changed and the non-polar groups were exposed to the surface of soy protein to develop the hydrophobic compartments in the core of SPI-SSPS nanogels, which might offer a promising potential for drugs encapsulating via hydrophobic attraction. The SPI-SSPS nanogels exhibited remarkable stability against pH and NaCl concentration change, and they were pretty stable against 120 d storage at 4 ℃. All of these valuable properties provide a great potential for practical application in the field of biomedicine.

Theoretical Studies on the [Y—C₈H₈—Y]²⁺ and L[Y—C₈H₈—Y]L (L=F, Cl, Br, I, Cp) Inverse Sandwiches with Y—Y Bond Passing Through the Ligand^†

LIU Nannan, YU Shuang, DING Yihong

2016, 37(11): 2006-2011. doi:10.7503/cjcu20160586

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The inverse sandwiches [Y—C₈H₈—Y]²⁺ and L[Y—C₈H₈—Y]L(L=F, Cl, Br, I) were theoretically investigated. The calculated results show that the singlet isomers with inverse sandwich configuration are the ground states, which are relatively stable against isomerization. [Y—C₈H₈—Y]²⁺and L[Y—C₈H₈—Y]L(M=Cl, Br, I) have distinct Y—Y metallic bond passing through the center hole of C₈H₈ ligand, yet the Y—Y interaction in F[Y—C₈H₈—Y]F is very weak. Besides, the multiple-decker sandwich Cp[Y—C₈H₈—Y]Cp(Cp=C₅H₅) also has Y—Y metallic bond passing through the center ligand. The results also show that the stronger the Y—Y bond is, the higher the dissociation energy of coordinated complex is. The bond passing through the ligand makes a noticeable contribution to the stability of inverse sandwiches.

Post-synthetic Modification of UMCM-1-NH₂ as a Catalyst to Prepare β-Amino Alcohols^†

LIU Hong, WANG Zhengren, CHEN Hengze, ZHANG Ruichang, CHEN Chao, ZHANG Ning

2016, 37(11): 2012-2017. doi:10.7503/cjcu20160551

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By the method of post-synthetic modification of MOFs, salicylaldehyde was anchored to UMCM-1-NH₂ to give a Schiff base functionalized porous compound UMCM-1-NH-Sal. The copper ion can coordinate with N atoms and O atoms inside the channels of the compound to give another compound UMCM-1-NH-Sal-Cu. The compound could catalyze the ring-opening reaction of epoxides with amines to yield β-amino alcohols, and showed good catalytic performance in such reactions.

Theoretical Studies on the Structure and Adsorption Properties of Isomorphously Substituted FAU Zeolite^†

YANG Bingxing, YE Liping, GU Huijie, XU Huasheng, LUO Yong, LI Huiying

2016, 37(11): 2018-2024. doi:10.7503/cjcu20160449

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The adsorption of oxygenated chemicals(methanol, dimethyl ether, propionaldehyde) in channel structure of FAU type zeolite β cage, as well as the modification mechanism of Zn/Ca isomorphous substitution were investigated by means of density functional theory(DFT) calculations. The results indicate that methanol, dimethyl ether and propionaldehyde can chemisorb at the top site of the Al atom, while they can barely adsorb at the Si atom. For Zn-/Ca-doped β cage, Al³⁺ was substituted by Zn²⁺/Ca²⁺, a hole was formed on the adjacent Si atom due to the loss of one electron, therefore the adsorption of methanol, dimethyl ether and propionaldehyde were enhanced. However, the dopant atom itself doesn’t serve as adsorption site.

Synthesis and Anti-corrosion Properties of Polyaniline/Polypyrrole-nano Silicon Dioxide Composite Membrane^†

LI Chuanxian, SHI Enhua, YANG Shuang, YAO Bo, YANG Fei, YAN Qun

2016, 37(11): 2025-2033. doi:10.7503/cjcu20160390

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In this article, polyaniline/polypyrrole-nanosilicon dioxide(PAni/PPy-SiO₂) composite membrane was prepared by cyclic voltammetry(CV) method on the surface of 316 stainless steel(316SS). The electrochemical polymerization process, structural and morphological characteristics of polyaniline(PAni), polyaniline/polypyrrole(PAni/PPy) and PAni/PPy-SiO₂ membranes were investigated by cyclic voltammetry(CV), Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM), respectively. The antiseptic properties of PAni, PAni/PPy and PAni/PPy-SiO₂ membranes to stainless steel were studied by the Tafel polarization curve and electrochemical impedance spectroscopy(EIS) in 3.5%(mass fraction) NaCl aqueous solution. The results show that PAni/PPy-SiO₂ composite membrane can form on the surface of 316 stainless steel by electrochemical process. Compared with PAni and PAni/PPy membranes, PAni/PPy-SiO₂ composite membrane has tighter surface structure. The metal protection ability of PAni/PPy-SiO₂ is better than those of PAni/PPy and PAni membranes. The anti-corrosion ability of membrane is improved because of the strengthening mechanical shielding effect of membrane with nano SiO₂ and the inhibition of charge transfer during the corrosion reaction process.

Synthesis of Highly Dispersed Au Nanoparticles Modified N-Doped TiO₂ Nanotubes by the Assist of Lysine and Their Photocatalytic Activity^†

AN Huiqin, YU Yucai, YAN Lin, WU Tingting, LI Xiaofeng, HE Xiaoling, ZHAO Lizhi, HUANG Weiping

2016, 37(11): 2034-2042. doi:10.7503/cjcu20160377

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N-doped TiO₂ nanotubes were synthesized by the combination of sol-gel and hydrothermal methods firstly; and then Au nanoparticles were deposited on the N-doped TiO₂ nanotubes by a simple one-pot process with lysine as both the linker and capping agent. The morphology, structure, optical absorption and composition of the samples were characterized by means of TEM, XRD, UV-Vis and XPS. The photodegradation rates of methyl orange under UV light irradiation were used to evaluate the photocatalytic activities of samples. The effects of N content, Au content, lysine and calcination on the photocatalytic activities of Au/N-doped TiO₂ nanotubes were discussed. The results exhibit that Au nanoparticles capped by lysine are highly dispersed on the support without any aggregation and the obtained sample exhibits higher photocatalytic activity in comparison with pure TiO₂ nanotubes. The improved photocatalytic activity is attributed to the narrower band gap of N-doped TiO₂, the high dispersion of Au nanoparticles and the reduced recombination of photogenerated electrons and holes caused by the formation of metal-semiconductor Schottky junction between Au and TiO₂.

Kinetic Studies of All-carbon Porous Structure on the Adsorption of Methylene Blue^†

SUO Lulu, LI Shengjuan, LI Yingtao, ZHANG Li, ZHANG Xi

2016, 37(11): 2043-2049. doi:10.7503/cjcu20160366

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The three-dimensional all-carbon porous structures(ACPs) were synthesized via low-temperature calcination which used carbon nanotubes(CNTs) as a skeleton, polymethyl methacrylate(PMMA) as pore former. ACPs were investigated by means of scanning electron microscope(SEM), transmission electron microscope(TEM), X-ray diffraction(XRD), Raman analysis(RAMAN) and specific surface area test(BET). The adsorbent activities of the ACPs were evaluated for the reduction of methylene blue(MB). The results show that adsorption rates fit well with pseudo second order kinetics model. Maximum adsorption capacity of the structure to MB was estimated by extrapolating equilibrium adsorption amounts at different dye concentrations using the Langmuir isotherm. It was found to be about 151.3 mg/g.

Preparation and Decontamination Capability of Hollow Zn-Cr Ferrite/Titanium Dioxide Composites^†

SUN Daihong, LIU Huarong, LI Ruizhe

2016, 37(11): 2050-2059. doi:10.7503/cjcu20160340

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Homogeneous and dispersive carbon nanosphere was synthesized by hydrothermal method using glucose as the material. Hollow Cr-Zn ferrite was prepared by coprecipitation method and thermal treatment technology using carbon sphere as template. Ferrite/titanium dioxide composites were obtained by coating titanium dioxide on the ferrite using tetrabutyltitanate as titanic source. The structure, morphology, electromagnetic performance of as-prepared samples and their absorptivity and degradability on dye wastewater were studied by modern analytical techniques. The results showed that the hollow ZnCr_0.25Fe_1.75O₄ has preferable photocatalytic property on dye wastewater, and its removal efficiency on methyl orange and Rhodamine B are about 87% and 83%, respectively. The coating of TiO₂ on the ferrite could improve photocatalytic activity of as-prepared sample, the ZnCr_0.25Fe_1.75O₄/TiO₂ composite with 23.08% of TiO₂ content has excellent photo-catalytic activity, and is equivalent to pure TiO₂.

Oligomerization of Biomass Cracking Gas to Gasoline Distillates over Amorphous Silica-alumina^†

ZHANG Qian, DING Mingyue, ZHANG Yulan, LI Yuping, WANG Chenguang, WANG Tiejun, MA Longlong

2016, 37(11): 2060-2067. doi:10.7503/cjcu20160309

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The oligomerization performances of biomass cracking gas over amorphous silica-alumina(ASA) were investigated in a fixed bed in the region of 100—320 ℃ and 2.0—4.0 MPa. NH₃-TPD, Py-IR, TG, SEM, BET and XRD were used to characterize the surface structures, acidity properties and carbon deposition of catalysts. The results showed that there were different degrees of acid amount loss and carbon deposition for ASA during oligomerization under different reaction conditions. The loss of Lewis acid amount decreased gra-dually with increasing temperature, and reached the minimum at 280 ℃, and then begun to increase with continual increase of temperature. The increase of pressure is beneficial to reduce the Lewis acid loss. The change trend of carbon deposition was consistent with that of Lewis acid loss. During oligomerization, the conversion of light olefins and yield of gasoline range products increased gradually with the increase of temperature and pressure, and reached the maximum at 4.0 MPa and 280 ℃. The conversions of ethylene, propylene and butylene reached 19.2%, 37.3% and 58.7%, respectively. The yield of gasoline range product reached 22.9%(molar fraction), and the selectivity of C⁵⁺olefins reached 73.5%.

Synthesis and Gel Properties of a Novel Amide Gelator with Melamine Moieties and Rationalizing Gelation Behavior by Hansen Solubility Parameters^†

WANG Xiao, YANG Xinguo, SHEN Qili

2016, 37(11): 2068-2075. doi:10.7503/cjcu20160268

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A novel amide gelator with melamine moieties(AMOG) was designed and synthesized. Gelator AMOG is capable of forming gel in various common organic solvents and the critical gelation concentration(CGC) of the gels formed in toluene and xylene are as low as 1 mmol/L. Tube inversion method is adopted to define the sol-gel transition temperature(T_gel) and the scanning electron microscope(SEM) is used to investigate micro-morphology of gels. The results of these tests exhibit obvious solvent effect on gelation behavior of AMOG. Further investigation for gelation behavior based on Hansen solubility parameters(HSPs) of solvents reveals that hydrogen bonding parameter(δ_h) has significant influence on the micro-morphology and properties of gels. 1.0 MPa^1/2<δ_h<4.1 MPa^1/2 for organic solvents is the favorable domain for transparent gels formation, opaque gels occur in the range of 4.1 MPa^1/2<δ_h<8.0 MPa^1/2 and solution/precipitation remain if δ_h is larger than 8.0 MPa^1/2. HSPs values for tested solvents are plotted as a point in Hansen space, which is constructed with δ_d, δ_p and δ_h as its three-dimensional coordinates. Most of the solvents that could form gels cluster in a certain region in above Hansen space. Sol-gel transition temperature is related to parameter δ_d and δ_p.

Preparation of Cyclodextrin-based Mesoporous Carbon and Its Catalytic Performance^†

WANG Huichun, WANG Fachun, LI Baolin

2016, 37(11): 2076-2084. doi:10.7503/cjcu20160216

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Mesoporous carbons with tailored pore size were prepared by technologies of ammonium perchlorate oxidation and hard template with hydroxypropyl-β-cyclodextrin as the structure-director and tetraethoxysilane as the silica precursor. The structures and surface chemistry properties of these carbon materials were characterized by N₂ adsorption, TEM, XRD and FTIR measurements. Their catalytic performances were investigated through the reduction of nitroaromatic using hydrazine hydrate as the reducing agent. The results showed that mesoporous carbon materials prepared using hydroxypropyl-β-cyclodextrin-based silicas as inorganic templates synthesized by ammonium perchlorate oxidation have worm-like pore structure and higher catalytic activity, especially mesoporous carbon prepared through oxidation under room temperature, the yield of p-methylaniline is 88.48% in the presence of the catalyst, and it still keeps higher activity after being reused for 4 times through a simple filtration, washed with ethanol and dried. Higher surface area and pore volume, and the presence of abundant surface oxygen-containing functional groups, which originates from the special preparation process of carbon material, are likely responsible for the high catalytic property of these mesoporous carbon materials.

Cobalt-mediated Radical Polymerization(CMRP) of Chloroprene by Co^Ⅱ(salen*)^†

LI Weiwei, SHI Yan, YANG Wantai, FU Zhifeng

2016, 37(11): 2085-2091. doi:10.7503/cjcu20160496

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Radical polymerization of chloroprene(CP) in the presence of N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine [Co^Ⅱ(salen*)], as a mediator was investigated. The results show that the induction time is shortened and the polymerization rate is increased with the increase of ABVN concentrations. The linear increase in molecular weight with conversion, and molecular weight close to the theoretical value at low conversion in benzene, demonstrating the living process of CP radical polymerization mediated by [Co^Ⅱ(salen*)]. In order to determine what effect, if any, the solvents had upon the control of the polymerization, various solvents were used in the CMRP of chloroprene, and the process in benzene efficiently controls the molar mass(characterized by size exclusion chromatography, SEC) at low monomer conversion. Then, the effect of electron donors(ED) on the [Co^Ⅱ(Salen*)]-mediated radical polymerization of CP was examined by the addition of electron donors, water, pyridine(Py), NEt₃, tetrahydrofuran(THF) and dimethylsulfoxide(DMSO) to the complex in the molar ratio [CP]/[Co]/[ABVN]/[ED]=400/1/3/25. The induction periods became shorter with the addition of electron donors(ED). Obviously, the control of polymerization increased with the addition of THF, which was demonstrated by molecular weight close to the theoretical value and a relatively narrow molecular weight distribution at low monomer conversion.

Utilizing Macromolecular Chain as Functional Monomer and Crosslinker to Imprint BSA with Preserving the Structural Integrity of Template^†

QIAN Liwei, LI Ji, SONG Wenqi, HU Xiaoling, GUAN Ping

2016, 37(11): 2092-2100. doi:10.7503/cjcu20160437

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Protein imprinted hydrogels were prepared via redox initiated polymerization by utilizing bovine serum albumin(BSA) as a template and poly(hydroxyethylacrylate-vinylimidazole-[1-(allylacetate)-3-vinyl-imidazolium]chloride) [P(HEA-co-VIM-co-[AVIM]Cl)] as the macromolecularly functional monomer and crosslinker. The analytical results of circular dichroism and synchronous fluorescence spectrum demonstrated that P(HEA-co-VIM-co-[AVIM]Cl) could effectively maintain the structural stability of BSA, while the equivalent HEA, VIM and [AVIM]Cl denatured the template protein. The selective and competitive adsorption experiments showed that the imprinted hydrogels made by P(HEA-co-VIM-co-[AVIM]Cl) obtained better selectivity and recognition ability compared with those made by HEA, VIM and [AVIM]Cl. Therefore, the above results suggested the significant advantage of maintaining the structural and conformational stability of template protein during the preparation of imprinted polymers. The strategy of using macromolecule monomer to imprint protein could effectively overcome the difficulty of mutability of protein, therefore would promote the development and application of protein imprinting technology.

Preparation, Structure and Properties of PLLA-TMC/PDLA-TMC Stereocomplexes^†

WU Xiaomeng, CHEN Xiaoyu, Shi LI, FAN Zhongyong

2016, 37(11): 2101-2107. doi:10.7503/cjcu20160363

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A series of copolymers with high molecular weight(M_n>1×10⁵) based on 1, 3-trimethylene carbonate(TMC) and L-lactide(L-LA) or D-lactide(D-LA) was synthesized by ring-opening polymerization using stannous octoate as catalyst. Then the stereocomplex sc-PLA films were prepared by mixing equal amount of the corresponding PLLA-TMC and PDLA-TMC solution and followed by solution casting. The chemical structure, thermal properties and enzymatic degradation behavior of sc-PLA films were characterized respectively. The results show that crystallinity of homochiral crystals in sc-PLA-TMC samples decreases with the increase of TMC content. Only stereocomplex crystals exist in sc-PLA-TMC samples when TMC contents beyond 5%. The enzymatic degradation results show that the degradation rate of samples is accelerated when TMC unit is introduced.

Properties of CeO₂/PTFE/Nafion Composite Membranes Prepared by Magnetron Sputtering^†

XIA Qingcheng, MAO Fei, YANG Yong, HAN Jing, LIU Xiaohui, YANG Jiazhi, SUN Dongping

2016, 37(11): 2108-2116. doi:10.7503/cjcu20160282

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CeO₂/PTFE composite membranes(PTFE=polytetrafluoroethylene) were prepared by magnetron sputtering CeO₂ on the surface of PTFE microporous membranes. The membranes were characterized by XPS and SEM. The properties of the membranes, such as contact angle, tensile strength were investigated. It was found that high quality CeO₂/PTFE composite membranes were obtained under the optimized magnetron sputtering: sputtering time of 120 s and magnetic sputtering power of 40 W. The CeO₂/PTFE composite membranes exhibited better comprehensive performance: favorable hydrophibility and tensile strength. In order to improve the performance of CeO₂/PTFE composite membranes, CeO₂/PTFE/Nafion composite membranes were prepared by Nafion casting. The properties of the composite membrane such as water uptake, ion conductivity were investigated. The water uptake and ion conductivity of CeO₂/PTFE /Nafion composite membranes were 30%, 0.071 S/cm, respectively.

Preparation of Hierarchically Structured AOPAN@Mg(OH)₂ Composite Nanofibrous Membrane and Cr(Ⅵ)-removal Capacity^†

ZHANG Fan, WANG Bin, WANG Jiaona, LI Xiuyan, LI Congju

2016, 37(11): 2117-2124. doi:10.7503/cjcu20160217

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The hierarchial aminated polyacrylonitrile(AOPAN)@Mg(OH)₂ composite nanofibrous membrane was obtained by electrospinning technique and surface modification with hydroxylamine chloride prior to hydrothermal method. The composite nanofibrous membranes were characterized by Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), X-ray diffraction(XRD) and transmission electron microscope(TEM) to confirm the formation of Mg(OH)₂ nanoparticles on the AOPAN nanofibers. The results revealed that 40 ℃/7 h was the best hydrothermal condition and Mg(OH)₂ nanoparticles were effectively loaded on the surface of AOPAN nanofibrous membrane. The adsorption process showed pH dependence and the maximum Cr(Ⅵ) adsorption occurred at pH=2. The Langmuir adsorption model described well the experimental adsorption data and estimated a maximum loading capacity of 123.5 mg/g. This is mainly due to the protonation of —NH₂ groups and Mg(OH)₂ nanoparticles under the acid condition, which is benefit for adsorbing HCr $O 4 -$ . The kinetics studies indicated that the adsorption equilibrium was attained after 5 h and the experimental data followed the pseudo-second order model. Meanwhile, the AOPAN@Mg(OH)₂ composite nanofibrous membrane can be easily separated from liquid solutions and shows excellent cyclic utilization performance. The composite membrane maintained over 50% removal rate after rinsing with dilute NaOH solution by four cycles. Therefore, the AOPAN@Mg(OH)₂ composite nanofibrous membrane could be a good candidate for removing Cr(Ⅵ) from wastewater, and the study provides a simple and effective route for the development of new environmental remediation nanomaterials.

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