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10 November 2013, Volume 34 Issue 11

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Cover and Content of Chemical Journal of Chinese Universities Vol.34 No.11(2013)

2013, 34(11):  0-0. 

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Article: Inorganic Chemistry

Preparation of High Stable Metal-organic Coordination Polymer Membrane with Xylene Isomers Separation Properties

KANG Zi-Xi, XUE Ming, FAN Li-Li, HUANG Lin, WEI Guo-Ying, QIU Shi-Lun

2013, 34(11):  2457-2461.  doi:10.7503/cjcu20130747

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High stable metal-organic coordination polymer membrane was prepared by a seeding-second growth method at solvothermal condition on porous silica substrate. The morphology, structure and properties of the synthesized membrane were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), single gas permeation test and separation test of xylene mixture. The pervaporation process gave the result that this porous membrane exhibited separation performance for xylene mixture by selective adsorption. Furthermore, the thermal stability and mechanical resistence of membrane were proved by heating, ultrasonic treatment and repeated separation test.



Oxidative DNA Cleavage Mediated by Water-soluble Carboxyl Iron(Ⅲ) Corrole

ZHANG Yang, CHEN Huan, WEN Jin-Yan, WANG Xiang-Li, WANG Hui, JI Liang-Nian, LIU Hai-Yang

2013, 34(11):  2462-2469.  doi:10.7503/cjcu20130610

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A new water-soluble iron corrole, 5,10,15-tris[4-(carboxy)phenyl] corrolato-iron(Ⅲ)(Fe^ⅢTCPC), was synthesized and characterized. UV-Vis, fluorescence and CD spectra, as well as relative viscosity were used to study the interaction between Fe^ⅢTCPC and ct-DNA. Agarose gel electrophrosis was also carried out to investigate the oxidative cleavage ability of Fe^ⅢTCPC to pBR322 DNA in the presence of hydrogen peroxide(H₂O₂) or tert an outside binding mode with intrinsic binding constant K_b of 1.96×10⁵ L·mol^-1. In the presence of H₂O₂ or TBPH, Fe^ⅢTCPC exhibits good oxidative cleavage activity toward pBR322 DNA, and TBPH shows a higher oxidative efficiency. Inhibitor tests reveal that neither the hydroxyl radicals nor singlet oxygen is involved in Fe^ⅢTCPC mediated DNA oxidative cleavage. It is suggested that (oxo)iron(V) corrole is the possible active intermediate involved in DNA oxidative damage.



Synthesis of ZnO/C/SNTs Using Zn-MOF as Template and Their Drug Delivery Ability

LI Zong-Qun, WANG Ai, GUO Chun-Yan, HU Wen-Na, TAI Yan-Fang

2013, 34(11):  2470-2477.  doi:10.7503/cjcu20130580

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Nanocrystallines of metal-organic framework [Zn₆(OH)₃(BTC)₃(H₂O)₃] ·7H₂O(Zn-MOF, BTC=benzene-1,3,5-tricarboxylate) coated with SiO₂ nanotubes(SNTs) were synthesized by a simple one-step ultrasonic route. ZnO/C/SNTs hybrid composites were produced by thermolysis of Zn-MOF/SNTs in N₂ environments, then the drug assemblies of Zn(IBU)₂/C/SNTs were synthesized by the reaction of ibuprofen(HIBU) and ZnO/C/SNTs. The morphology and structure of nanoparticle were characterized by transmission electron microscopy(TEM), high resolution transmission electron microscopy(HRTEM), Fourier transform infrared spectrometry(FTIR) and X-ray diffraction(XRD). The results show that the Zn-MOF/SNTs have clear core-shell structure with rod-like shape, same-sized and well-dispersed. The as-prepared SNTs have better structure stability and the morphologies remain unchangeable after calcination. The results demonstrated that the drug loading was about 752 mg/g, and the drug assemblies had an excellent pH responsive behavior.



Analytical Chemistry

Synthesis and Fluorescence Property of Novel AgInS₂@ZnS Quantum Dots

LV Jian-Quan, HU Qin-Qin, DING Ran, ZHANG Xia, ZHOU Xing-Wang

2013, 34(11):  2478-2482.  doi:10.7503/cjcu20130773

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A novel water-soluble AgInS₂@ZnS quantum dots(AgInS₂@ZnS QDs) in aqueous solution was synthesized. The preparation of AgInS₂@ZnS QDs includes the formation of AgInS₂ core with denatured bovine serum albumin(dBSA) as the stabilizer and the coating of ZnS on the surface of the core. The effects of ingredient and conditions on the fluorescence of AgInS₂@ZnS QDs were investigated. The characterizations of AgInS₂@ZnS QDs were studied via X-ray diffraction pattern(XRD), scanning tunneling microscopy(STM) and so on. The results show that AgInS₂@ZnS QDs are a core-shell nano-materials, the size range of the resultant particles is 5-7 nm, and the quantum yield is determined to be 35.3%.



Synthesis of N,N-Dimethyl Pyridine Benzaldehyde-4-dimethylaminobenzoylhydrazone and Its Application for Selective Recognizing Cu²⁺

HAN Bing-Xing, WU Fang-Ying

2013, 34(11):  2483-2487.  doi:10.7503/cjcu20130669

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A fluorescence chemosensor, N,N-dimethyl pyridine benzaldehyde-4-dimethylaminobenzoylhydrazone was synthesized and confirmed by means of ¹H NMR, ¹³C NMR and MS. The interactions between the metal ions and compound 1 were investigated via fluorescence spectrophotometry and UV-Vis spectroscopy. The results indicated that compound 1 showed a highly selective response to Cu²⁺. The addition of Cu²⁺ induced a dramatic enhancement in the fluorescence of compound 1 by 12.5 folds, whereas the other metal ions had little fluorescence quenching, for example Fe³⁺, Zn²⁺, Pb²⁺, Hg²⁺, Cd²⁺, Co²⁺, Ni²⁺, Li⁺, K⁺, Ca²⁺, Mg²⁺ and Ag⁺. Double reciprocal linear plot method showed that compound 1 coordinated with Cu²⁺ to form 1: 1 stable luminescent complex and the binding constants was ca. 2.0×10⁷ L/mol.



Ultrasensitive Surface-enhanced Raman Scattering Detection with Nanoparticle-functionalized Amino Silica Monolith

LIU Chan, JIANG Qian, CHEN Lei, ZHANG Hou, CHEN Huai-Xia, ZHOU Ji, YE Yong

2013, 34(11):  2488-2492.  doi:10.7503/cjcu20130623

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A novel type of amino silica monolith was developed by the sol-gel reaction combined with a supramolecular template-based approach in a simple and rapid manner. By the co-condensation of tetraethoxysilane(TEOS) and (3-aminopropyl)triethoxysilane(APTES) in the presence of cetyltrimethylammonium bromide(CTMAB), the silica-based hybrid material with active amino groups bonded to the silicon atoms was obtained. After injecting a gold nanoparticles(AuNPs) colloid into the monolith, a very dense homogeneous coverage of AuNPs was obtained and all AuNPs were assembled directly on the monolith surface. The nanoparticle-functionalized monolith was then used for a surface-enhanced Raman scattering(SERS) substrate and it provided high enhancement activity and reproducibility. The minimum detectable concentration of this SERS column is 10^-9 mol/L for PATP and 10^-11 mol/L for crystal violet(CV). This nanoparticle-functionalized amino silica monolith will be powerful SERS substrate for ultrasensitive detection of toxins and contaminants in the field.



Liquid Crystal Biosensor Based on Growth of Gold Nanoparticles for Detection of Tyrosine

LI Guang, CHEN Long-Cong, CHEN Meng-Meng, GAO Bin, XIONG Xing-Liang

2013, 34(11):  2493-2498.  doi:10.7503/cjcu20130536

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A new-style liquid crystal(LC) biosensor based on enzymatic growth of gold nanoparticles(AuNPs) was developed for detection of tyrosine(Tyr). Tyrosinase(TR) was immobilized on the glass slides modified with APTES/DMOAP mixed self-assembled monolayers(SAM) and activated by glutaraldehyde, which, afterwards, were immersed in a growth solution containing different concentrations of Tyr. In this me-thod, TR stimulated the biocatalyzed hydroxylation of Tyr to L-Dopa which could reduce Au³⁺ in the growth solution into AuNPs. The formation of AuNPs could greatly change the surface topology and induce a homeotropic-to-tiled transition of the LC molecules, resulting in significant change in corresponding of optical appea-rances under the crossed polarized light. The results showed that the presented LC biosensor can highly sensitive to Tyr with a limit of detection of 6×10^-7 mol/L. Furthermore, this study offers a simple, high-specific and label-free method with naked eye for Tyr.



Rapid Determination of Diethanolamine by Field Asymmetric Ion Mobility Spectrometry(FAIMS) Technique

TAO Yu-Yu, LI Ling-Feng, LI Xin, LI Peng, WANG Xiao-Zhi

2013, 34(11):  2499-2504.  doi:10.7503/cjcu20130466

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The field asymmetric ion mobility spectrometry(FAIMS) technique was used for the rapid analysis of diethanolamine(DEA). The ion characteristic signal of DEA was acquired by FAIMS with the direct thermal desorption method for sampling, which was compared with the result of gas chromatograph-mass spectrometer(GC-MS). The concentration of DEA gas was controlled by the polytetrafluoroethene(PTFE) diffusion tube method. The DEA gas samples with different concentrations were detected by FAIMS technique. The dependence of the integrated ion current on DEA gas concentration was obtained, and the limit of detection for DEA gas is 0.02 μg/L. This study has laid a foundation for the application of FAIMS technique to on-site rapid detection of DEA.



SERS and EEM Fluorescence Spectral Distinction of Sudan Ⅰ and Paprika Red in Food

LIU Chun-Yu, WANG Shao-Yan, XU Shu-Ping, XU Wei-Qing

2013, 34(11):  2505-2510.  doi:10.7503/cjcu20130379

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Surface enhanced Raman scattering(SERS) and excitation-emission matrix(EEM) fluorescence spectroscopy were employed to determine an illegal food additive(Sudan Ⅰ) and legitimate food additive(paprika red). SERS spectra show that the torsion vibration modes of Sudan I is obviously enhanced in lower frequency range while the peaks of paprika red at 1521 and 1158 cm^-1 are great enhanced as well. EEM fluorescence spectra show that Sudan Ⅰ has two obvious characteristic fluorescence peaks at P₁(λ_ex=285 nm, λ_em=345 nm) and P₂(λ_ex=335 nm, λ_em=548 nm). Paprika red has three characteristic fluorescence peaks at P₁(λ_ex=545 nm, λ_em=580 nm), P₂(λ_ex=560 nm, λ_em=665 nm) and P₃(λ_ex=608 nm, λ_em=672 nm). The spectral information provided the references for accurate and rapid detection of Sudan Ⅰ in food.



Organic Chemistry

Synthesis and Catalytic Activity of Ferrocenyl-substituted N-Heterocyclic Carbene Silver Complexes

LI Qiang, SUN Bao-Chuan, SONG Hai-Bin, TANG Liang-Fu

2013, 34(11):  2511-2516.  doi:10.7503/cjcu20130254

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Ferrocenyl-substituted N-heterocyclic carbene(NHC) transition metal complexes have received considerable attention in recent years due to their extensive applications in homogenous catalysis or electrochemical investigation. In this work, four NHC-silver complexes(NHC)₂AgX(X=PF₆ or BF₄) were synthesized by the reactions of N-ferrocenylmethyl-N'-(pyridylmethyl)imidazolium salts with Ag₂O under the phase transfer catalytic conditions, and were characterized by elemental analysis, NMR and single-crystal X-ray crystallographic analysis. The silver atom in four complexes showed a two-coordinated linear structure. The pyridyl nitrogen atom didn't take part in the coordination to the silver center. Those complexes exhibited highly effective catalytic activity in the three-component coupling reaction of aldehyde, alkyne and amine.



Bioactive Change and Structural Change of Bacillus Amyloliquefaciens α-Amylases Induced by Ca²⁺

JI Xu, BIAN Liu-Jiao

2013, 34(11):  2517-2523.  doi:10.7503/cjcu20130226

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Based on the effect of bivalent calcium ions(Ca²⁺) on the biological activity of Bacillus amyloliquefaciens α-amylases, the structural change of Bacillus amyloliquefaciens α-amylases induced by Ca²⁺ was studied via fluorescence spectroscopy and Fourier-transformation infrared spectroscopy. The results showed that when the concentration of Ca²⁺ in solution was below 25 mmol/L, the enzyme molecules could be activated by Ca\+2+ in solution, when the concentration of Ca²⁺ was over 25 mmol/L, the biological activity of enzyme molecules could be inhibited by Ca²⁺. In the structural change of Bacillus amyloliquefaciens α-amylases induced by Ca²⁺, only their secondary structures rather than their tertiary structures were involved; and when Ca²⁺ showed an activation effect to the bioactivity of the enzyme molecules, the contents of disorder structures and β-sheet structures in the enzyme molecules decreased, and the α-helix ones and the β-turn ones increased. Whereas when Ca²⁺ showed an inhibition effect to the bioactivity of the enzyme molecules, the α-helix structures and β-turn structures in the enzyme molecules decreased, and disorder ones and the β-sheet ones in the enzyme molecules increased.



Synthesis of 6-Amino-2-alkylthio Adenosine and Their Anti-platelet Aggregation Activity

WEI Yong-Ji, LI Shun-Lai, YU Ming-Wu, DU Hong-Guang

2013, 34(11):  2524-2530.  doi:10.7503/cjcu20130198

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Some purine derivatives are effective inhibitors of platelet aggregation. Guanosine(1), as the starting material, was protected by acetic anhydride to get 2',3',5' -tri-O-acetyl-guanosine(2), then chlorinated with phosphorus oxychloride to obtain 2-amino-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purine(3). Compound 3 was diazotized with isoamyl nitrite and then reacted with dialkyl disulfides to afford 2-alkyl(aryl)thio-6-chloro-9-(2',3',5'-tri-O-acetyl-β-D-ribofuranosyl)purines(4a-4d). 6-Amino-2-alkylthio adenosine(5a-5l) were acquired by aminolysis and deprotection reaction of compounds 4a-4d. The structures of the compounds were identified by ¹H NMR, ¹³C NMR, IR and high resolution mass spectrometer(HRMS). In addition, the platelet aggregation rates(PAR) for the final compounds were measured. The results show that these compounds have a certain anti-platelet aggregation activity under 10 μmol/L. 6-(3-Phenyl propyl)azyl-2-propylthio adenosine has the most significant activity, the PAR was up to 9.8%.



Synthesis and Antitumor Activities of 3-Arylbenzofunanone Analogues

LV Ze-Liang, GAO Yang, LI Jun, HUANG Tong-Kun, HE Shu-Jie, ZOU Yong

2013, 34(11):  2531-2539.  doi:10.7503/cjcu20130185

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Starting from methoxyl-substituted benzaldehydes and chloroform, a series of methoxyl-substituted mandelic sodium salts were synthesized in the presence of sodium hydroxide and catalytic amount of tetrabuty-lammonium bromide(TBAB), the corresponding methoxyl-substituted mandelic acids could readily be obtained by acidification. These intermediates on reaction with various substituted phenols in the presence of boron trifluoride etherate via a sequential esterification-alkylation process to give 13 3-arylbenzofunanone analogues in high yields with simple procedures. The inhibitory effects of 11 compounds on cell proliferation were investigated by methylthiazolyldiphenyl-tetrazolium bromide(MTT) method using SW620, A549 and MNNG/HOS cell lines. The results showed that the 3-arylbenzofunanone analogues 4a, 4j and 4a, 4i exhibited some activities against the proliferation of the cell lines.



Active Peptide from Acetes Chinensis with Inhibitory Activity on Neuraminidase of Influenza Virus

WANG Hai-Tao, WANG Wei, CHEN Ming, YUAN Ning, ZHAO Yuan-Hui, MAO Xiang-Zhao

2013, 34(11):  2540-2545.  doi:10.7503/cjcu20130334

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Low-valued Acetes Chinensis was chosen to prepare the enzymatic hydrolysate with neuraminidase(NA) inhibitory activity by controlled hydrolysis. A novel NA inhibitory peptide was purified by gel chromatography and reversed phase high performance liquid chromatography. The IC₅₀ value of the peptide was only 96.1 μmol/L and it could also significantly inhibit influenza A virus replication in MDCK cells. The amino acid sequence of this peptide was EISYIHAEAYRRGELK which identified by LC-MS/MS and its binding with NA protein was proved by UV spectrum analysis. The accurate sites of NA protein that the peptide bind to were determined using the computer assisted software SYBYL. The largest non-toxic concentration(TC₀) was 1.26 mg/mL which assayed by cell cytotoxicity experiments. The hemagglutination essay showed that this pepetide could obviously decrease the agglutination titer influenza virus in a dose-dependent manner which suggested that the antiviral activity of this peptide might be attributed to its action on multiple targets.



Physical Chemistry

NLO Property for the Multi Li-doped Chain Molecules H(HC=N-Li)_nH(n=1-6) and Dependence of Chain Length

BAI Yang, WANG Jia-Jun, ZHOU Zhong-Jun, LI Ying, WU Di, LI Zhi-Ru, SUN Chia-Chung

2013, 34(11):  2546-2550.  doi:10.7503/cjcu20130696

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The alkali-metal doped system with excess electron is a new kind of potential materials having large non-linear optical(NLO) response. The structures and properties of the multi Li-doped chain molecules H(HCN-Li)_nH(n=1-6) were reported in this paper. Interestingly, with the increasing of chain length n, two kinds of molecules emerge. For n=1 and 2, the Li-salt molecules are formed because the excess electron orbitals are unoccupied. But for n=3-6, excess electron orbitals are occupied and multi-Li electrides with wide-range excess electron cloud are formed. For the multi Li-doped chain system, the dependence on NLO properties is unordinary stepped increase, 2179, 2776(n=1, 2)<5492, 5487(n=3, 4)<15235, 15377(n=5, 6). It demonstrates that multi-Li doping can generate wide-range excess electron cloud and large NLO response. The new knowledge enriches the design ideas for NLO materials.



Photodimerization of Cinnamoyl Moiety in the Hydrophobic Chains of Gemini Surfactant

FAN Hai-Ming, ZHU Xiao-Ming, YAN Yun, HUANG Jian-Bin, KANG Wan-Li

2013, 34(11):  2551-2557.  doi:10.7503/cjcu20130582

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The photochemistry processes and products of Gemini surfactant sodium N,N'-di(4-n-butyloxy cinnamoyl)-L-cystine(SDBCC) were investigated by UV absorption spectra, IR spectra and mass spectrum. The influences of SDBCC concentration on the photochemical reaction products distribution and photodimerization yield were analyzed. The photodimerization takes place more favorably for the photochemistry processes of cinnamoyl moiety in the hydrophobic chains of SDBCC at different concentrations and the photodimerizaiton product all formed by intramolecular reaction. However, the variation trends of cinnamoyl moiety photodime-rization yield with SDBCC concentrations are different. The dimerization yield increases with concentration before aggregates formation, whereas the dimerization yield decreases with concentration after aggregates formation. The effects of micelle and vesicle formation on the photodimerization of cinnamoyl moieties in SDBCC hydrophobic chains were further analyzed by combination of photochemistry processes, topochemical stipulated condition and aggregate structures.



Sensitivity Criterion and Mechanical Properties Prediction of HMX and RDX Crystals at Different Temperatures Comparative Study with Molecular Dymamics Simulation

LIU Dong-Mei, ZHAO Li, XIAO Ji-Jun, CHEN Jun, JI Guang-Fu, ZHU Wei, ZHAO Feng, WU Qiang, XIAO He-Min

2013, 34(11):  2558-2565.  doi:10.7503/cjcu20130568

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In order to explore and compare the progressive changes of structure, energetic and mechanical properties of RDX(cyclotrimethylene trinitramine) and HMX(cyclotetramethylene tetranitramine) crystals with temperature, molecular dynamics simulation was conducted for their suitable models containing the same number of atoms. COMPASS force field was applied in the simulation in NPT ensemble. Five different temperatures, i.e., 195, 245, 295, 345 and 395 K, were considered. The simulation results show that the maximum bond length(L_max) of their N-N trigger bond increases, the interaction energy(E_N-N) between two N atoms of the N-N trigger bond decreases and the cohesive energy density(CED)decreases as the temperature increases. These results agree with the experimental fact that both RDX and HMX become more sensitive as the temperature increases. Moreover, the L_max value of RDX is larger than that of HMX, and the values of E_N-N and CEDof RDX are lower than those of HMX at all temperatures. These also agree with the fact that RDX is more sensitive than HMX. It is thus suggested that the L_max, E_N-N and CED indeed can be used as theoretical criteria to predict the relative degree of heat and impact sensitivity of high energy materials under certain conditions. The mechanical properties were obtained with static analysis method. The results show that the engineering modulus such as tensile modulus, bulk modulus and shear modulus decrease with the increasing temperature, which agrees with the experimental results.



Theoretical Research on Self-assembly System of Molecular Imprinted Polymers Formed by Ciprofloxacin and Trifluoromethacrylic Acid

LIU Jun-Bo, TANG Shan-Shan, SUN Jia-Ni, JIN Rui-Fa

2013, 34(11):  2566-2573.  doi:10.7503/cjcu20130514

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Long range corrections are applied to simulations of the self-assembly system of the molecularly imprinted polymers(CIP-MIPs) formed by ciprofloxacin(CIP) and trifluoromethacrylic acid(TFMAA). CIP was taken as the template molecule and TFMAA was taken as the monomer. The geometry optimization, the bon-ding situation, and the binding energies of CIP with TFMAA in different proportions were studied. The selecti-vity had also been discussed. The results indicate that CIP and TFMAA form ordered compounds via the hydrogen bonding. The compounds were mutual remedy in the molecular structure. The polymer with the molar ratio of CIP-TFMAA(1: 6) had the lowest binding energy. By simulating the rebinding energies between the ENR, NOR, OFL and CIP-MIPS after the elution of CIP, the selectivity of the CIP-MIPs to CIP imprinting molecules was predicted. The selectivity of CIP-MIPs to CIP is excellent with the presence of both CIP and OFL. In addition, the CIP-MIPs of different imprinting ratios of CIP and TFMAA were prepared to study the binding capacity of the polymers. The experimental results show that the CIP-MIPs synthesized by CIP and TFMAA with the molar ratio of 1: 6 have the best binding capacity, and the selective factor of the CIP-MIPs to OFL is the largest. The conclusion of experiment was consistent with the results of calculation.



New Type ZMOFs for the Separation of CO₂ in Natural Gas

ZHENG Cheng-Cheng

2013, 34(11):  2574-2579.  doi:10.7503/cjcu20130490

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We reported a molecular simulation study for the separation of industrially gas mixtures in different ion-exchanged(Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Al³⁺) usf zeolite-like metal-organic framework(usf-ZMOF). The selectivities of the three systems(CO₂/CH₄, CO₂/N₂, CO₂/H₂) are higher than the average. For the different ion-exchanged usf-ZMOF, the selectivity enhances when the ion valences go up from positive one to three. In the same main group, the selectivity decreased with the atom number increasing. In our research, the highest one is Al-usf-ZMOF, in which at ambient temperature and pressure, the CO₂ adsorption selectivity is 290 for the CO₂/CH₄ mixture, 1.68×10⁴ for the CO₂/H₂ mixture, and 1.7×10³ for the CO₂/N₂ mixture. We find that the much higher selectivity is due to the strong interaction between CO₂ and ions. CO₂ assemble clusters around the ions to make the density even higher than liquid density in the nearest areas.



CuO/CeO₂ Catalysts Prepared by Iodic Acid Improved Sol-gel Method for Preferential CO Oxidation

SHEN Pan, CHEN Chao, WANG Rui, JIANG Wan, ZHANG Ning

2013, 34(11):  2580-2586.  doi:10.7503/cjcu20130468

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CuO/CeO₂ catalysts were prepared by iodic acid improved sol-gel method, and the catalytic performances for the preferential oxidation of CO in excess hydrogen were evaluated. Compared with the conventional catalysts, the catalytic activities of iodic acid modified catalysts were markedly improved. The catalysts were characterized by a series of techniques such as temperature-programmed reduction in H₂(H₂-TPR), X-ray diffraction(XRD), transmission electron microscope(TEM), X-ray photoelectron spectroscopy analysis(XPS) and energy dispersive spectrometer(EDS). It was found that the improved method offered catalysts with smaller crystallite size, higher dispersion, more surface actual content of Ce³⁺ and reduced CuO species, which led to improving the performance of catalysts.



Effect of Cu-Co Loading on Catalytic Performance of Cu-Co/TiO₂ Catalysts in Step-wise Conversion of CH₄ and Syngas

PENG Fen, HUANG Wei, HAN Tao

2013, 34(11):  2587-2593.  doi:10.7503/cjcu20130442

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A series of Cu-Co/TiO₂ catalysts with different Cu-Co loadings and Cu/Co mass ratio was prepared by equal volume impregnation. The catalysts performances were investigated for the direct synthesis of C₂⁺ oxygenates from CH₄ and syngas by a step-wise reaction technology. Several techniques, including N₂ physical adsorption-desorption(BET), temperature-programmed reduction of hydrogen(H₂-TPR), X-ray diffraction(XRD), temperature-programmed desorption of hydrogen nitride(NH₃-TPD) and temperature-programmed desorption of CO(CO-TPD) were used to characterize the catalysts. The results show that among all the catalysts, 18%(Cu₁₂-Co₆)/TiO₂ has the highest catalytic activity, the formation rate and selectivity of C₂⁺ oxygenates reached 19.92 mg·g_cat^-1·h^-1 and 67.76%, respectively. It is concluded that there is the interaction between the TiO₂ and the active metal Co-Cu as well as the good dispersion in the catalyst, the catalyst has high activity; Highly dispersed micro-crystal CuO that is conducive to catalytic hydrogenation and dehydrogenation reaction can promote the conversion of CH₄ and syngas. Besides, weak acid and mediate strong acid are beneficial to the conversion of CH₄ and syngas, but strong acid produces inhibitory action to the reaction.



Effects of Lithium Content on the Structural Properties and Catalytic Activities of CuLi/AC Catalysts in the Oxidative Carbonylation of Methanol to Dimethyl Carbonate

REN Jun, WANG Dong-Lei, PEI Yong-Li, QIN Zhi-Feng, LIN Jian-Ying, LI Zhong

2013, 34(11):  2594-2600.  doi:10.7503/cjcu20130429

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The CuLi/AC(active carbon) catalysts with different lithium contents were prepared by microwave heating and tested in the oxidative carbonylation of methanol to dimethyl carbonate(DMC). The bulk and surface properties of the catalysts were characterized by means of X-ray diffraction(XRD), H₂-temperature program reduction(H₂-TPR), X-ray photoelectron spectrum(XPS), scanning electron microscope(SEM), and CO-temperature programe desorption(CO-TPD) techniques. The results show that the addition of moderate content of lithium into the Cu/AC catalyst enhances the auto-reduction of copper species to Cu⁰, leading to more well-dispersed Cu nanoparticles with more uniform grain size on the surface of active carbon. The cataly-tic performance is related to the concentration of Cu⁰ in the surface of CuLi/AC catalysts, indicating that Cu⁰ species is the main active centers for the synthesis of DMC. The addition of lithium enhances CO weak adsorption centers, which favors the insertion reaction between CO molecules and Cu-OCH₃ intermediates, and thus effectively improve the catalytic activity of CuLi/AC catalysts. The STY(space time yield) of DMC firstly increases and then decreases with the content of lithium, and reaches the maximum of 540.6 mg·g^-1·h^-1 when the mass fraction of lithium is up to 0.15% in the catalysts, and the corresponding MeOH conversion and DMC selectivity are 4.5% and 81.4%, respectively.



Theoretical Study on Adsorption of 1,3,5-Trinitrobenzene Molecule on Kaolinite Surface

WANG Xing, QIAN Ping

2013, 34(11):  2601-2608.  doi:10.7503/cjcu20130413

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The cluster models Si₁₃O₃₇H₂₂ and Al₆O₂₄H₃₀ for tetrahedral(Si-O) and octahedral(Al-O) surfaces of kaolinite were constructed, respectively. The properties of interaction between 1,3,5-trinitrobenzene(TNB) molecule and kaolinite surface have been studied at the levels of B3LYP/6-31G(d), MP2/6-31G(d)//B3LYP/6-31G(d) and B3LYP/6-311++G(d,p)//B3LYP/6-31G(d), respectively. The computed properties characterizing complexes include optimal structures, structural parameters, adsorption energies, vibration frequencies, electrostatic potential maps, molecular orbitals, and so on. The results show that the interaction of TNB with the Si-O surface is governed by the electrostatic and van der Waals' interactions, and the interaction between TNB and Al-O surface is mainly provided by the hydrogen bonds. Simultaneously the binding energy between TNB molecule and Al-O surface is lower than that between TNB molecule and Si-O surface.



Effect of Pt on Hydrodesulfurization Performance of the Ni₂P/MCM-41 Catalyst

SONG Hua, XU Xiao-Wei, DAI Min, SONG Hua-Lin

2013, 34(11):  2609-2616.  doi:10.7503/cjcu20130406

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Nickel phosphide catalysts, Ni-P/MCM-41 adding with small amounts of Pt, were made by means of temperature programmed reduction method. The catalysts were characterized by hydrogen temperature programmed reduction(H₂-TPR), X-ray diffraction(XRD), N₂-adsorption specific surface area measurements, X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). The effects of different P/Ni molar ratio and amounts of Pt added on catalyst activity for dibenzothiophene(DBT) hydrodesulfurization(HDS) were studied. The results showed that the addition of Pt into the catalyst can decrease the reduction temperature of the Ni₂P catalysts, contribute to the formation of Ni₂P phase, inhibit reunite phenomenon and improve the HDS catalytic activity of Ni₂P catalysts. The HDS activity of the catalyst containing 0.6%Pt, with P/Ni molar ratio of 2 was found to be optimal. At reaction temperature of 340 ℃, pressure of 3.0 MPa, hydrogen/oil volume ratio of 500, and weight hourly space velocity(WHSV) of 2.0 h^-1, the conversion of dibenzothiophene HDS was 100%, and the HDS activity could remain stable within 120 h.



Preparation of Hydrophobic Cosalen/SBA-15 and Its Application in the Selective Oxidation of Toluene

DENG Ying, YUAN Pei, YUAN Xia, WU Jian, LUO He-An

2013, 34(11):  2617-2622.  doi:10.7503/cjcu20130370

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The mesoporous SBA-15 was functionalized by(3-aminopropyl)-triethoxysilane(APTES), and then hydrophobic modified with methyltriethoxysilane(MTES). The obtained material was used as carrier to immobilize N,N-bis(salicylidene)ethylenediiminocobalt(Cosalen) complex. The supported catalyst Cosalen/SBA-15 was characterized by means of Fourier transform infrared spectroscopy, diffuse reflectance ultroviolet visible spectroscopy, X-ray photoelectron spectrograph, elementary analysis, inductive coupled high frequency plasma, X-ray diffraction, N₂ adsorption-desorption techniques. The adsorption properties of samples for toluene, benzaldehyde and benzyl alcohol and catalytic performance for liquid-phase oxidation of to-luene were investigated. The results showed that the ordered mesoporous structure of SBA-15 carrier after mo-dification were retained; Cosalen was highly dispersed on the surface of SBA-15 by the coordination effect of NH₂ ligand. The hydrophobicity of samples with amino functionalization and methyl modification was obviously enhanced, and their adsorptive capacity for benzaldehyde and benzyl alcohol decreased. The liquid-phase solvent-free oxidation of toluene with molecular oxygen catalyzed by hydrophobic Cosalen/SBA-15 and NHPI effectively improves the products selectivity of benzaldehyde and benzyl alcohol to 32.0% with the conversion of toluene 16.0% at 130 ℃ for 2 h, which resulted from the prevention of deep oxidation of benzaldehyde and benzyl alcohol to benzonic acid to some extend. The investigation of temperature effect showed that high temperature was not good for the improvement of selectivity of benzaldehyde and benzyl alcohol. Lower tempe-rature to 110 ℃, the selectivity of benzaldehyde and benzyl alcohol was up to 43.9% with the conversion of toluene 12.9%.



Preparation of Bio-inspired NiO Nanowires/nanofibers Hierarchical Structures and Their Photocatalytic Properties

PAN Chao, DONG Li, MA Ling, YANG Gui-Juan

2013, 34(11):  2623-2628.  doi:10.7503/cjcu20130352

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Novel NiO nanowires/nanofibers(NWNFs) hierarchical structures were fabricated employing bottom-up strategy and electrospinning method. The synthesized hierarchical structures were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and nitrogen adsorption-desorption analysis methods. The catalytic efficiency of the NiO nanomaterials developed was evaluated by the photocatalytic degradation of methyleneblue(MB). In comparison with sphere-like and fiber-like structures, the photocatalytic removal rate of MB remains above 97% on the hierarchical NiO NWNFs catalyst under ultraviolet light irradiation for 180 min, which is 1.24 times and 2.16 times that of pure NiO fibers and nanoparticals, respectively. The NiO hierarchical structures show an excellent ability to degrade rapidly a MB pollutant, which may be attributed to its unique hierarchical and porous surface structures.



Effect of Microwave Irradiation on Physical Properties and Photocatalytic Activities of ZnO Nano-material

GAO Yu, LI Li, ZHANG Xiu-Li, WANG Li-Li, ZHANG Wen-Zhi, HUANG Xian-Dan

2013, 34(11):  2629-2634.  doi:10.7503/cjcu20130270

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A series of ZnO nano-materials was prepared by sedimentation method under different microwave power(100, 150, 200, 250 and 300 W) irradiation. The crystal structures, morphologies and surface physicochemical properties of the as-prepared samples were characterized by X-ray diffraction(XRD), UV-Vis diffuse reflectance spectrum(UV-Vis/DRS), scanning electron microscopy(SEM) and N₂ adsorption/desorption determination. The results indicate that the crystalline phase of ZnO sample with different microwave power irradiation is hexagonal wurtzite, moreover, compared with the ZnO prepared by conventional sedimentation, there are blue shift or red shift in the absorption spectra, and the specific surface area is increased more or less. The morphology of each ZnO sample is much distinctive because of the different microwave power, which shows many kinds of shape including nano-grain, oval nano-clusters, nano-plane, spherical nano-clusters and so on. Photocatalytic properties of the ZnO nano-materials were tested by the UV irradiation and microwave-assisted photodegradation of Rhodamine B(RhB). The results show that the photocatalytic activities of ZnO prepared under different microwave power irradiation are enhanced in different degrees, which are much higher than that of P25 and ZnO sample without microwave irradiation.



Preparation of Ag/AgCl-TiO₂ Hollow Nanoparticles by Co-precipitation and Their Photocatalytic Property

WANG Jin-Gang, JI Ping-Li, KONG Xiang-Zheng

2013, 34(11):  2635-2643.  doi:10.7503/cjcu20130219

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Anionic polystyrene(PSt) latex particles were prepared through emulsion polymerization of methacrylic acid and styrene(St). The PSt particles were surface-treated using vinyl trimethoxysilane in a mixed solvent of ethanol and water. PSt-AgCl-TiO₂ composite particles were then prepared through hydrolysis of tetrabutyl titanate and the reaction of AgNO₃ with NaCl using the surface treated PSt particles as templates. Ag/AgCl-TiO₂ hollow particles were obtained by pre-treating the PSt-AgCl-TiO₂ composite microspheres at 180 ℃ followed by drying and calcination at 500 ℃ for 4 h. XRD characterization of the final Ag/AgCl-TiO₂ particles reveals that anatase crystal structure in pure TiO₂ is unchanged with AgCl doping. EDS analysis shows that part of the added AgCl is transformed to Ag element, leading to the formation of the hollow Ag/AgCl doped TiO₂ composite particles. Surface area test indicates that average pore size in the Ag/AgCl-TiO₂ particles is about 12 nm with a specific surface varied from 125 m²/g to 190 m²/g, depending on the amount of AgCl. These specific surface values are much higher than that observed in commercial TiO₂, P25 for instance. Photocatalytic activity of the Ag/AgCl-TiO₂ hollow particles in degradation of Rhodamine B(RhB) was tested under UV and visible light. The results show that, compared with RhB degradation with pure TiO₂ hollow particles under UV light, RhB degradation at 30 min increases by about 13% when Ag/AgCl-TiO₂ particles with Ag content at n(Ag)/n(Ti)=0.1% is used as the catalyst; whereas an increase of about 38% is observed under visible light with Ag/AgCl-TiO₂ composite particles[n(Ag)/n(Ti)=2.0%] at 120 min of the photodegradation. In addition, the photocatalytic activity of the Ag/AgCl-TiO₂ particles under visible light is increasing with Ag amount up to n(Ag)/n(Ti)=2.0%, and this catalytic activity starts to decrease when Ag amount reaches n(Ag)/n(Ti)=4.0%. Nevertheless, all the Ag/AgCl-TiO₂ particles demonstrate a higher photocatalytic performance than P25, regardless of their AgCl content. The photocatalysis mechanism of the Ag/AgCl-TiO₂ particles was provided, and the results were interpreted based on the mechanism.



Effect of Polyelectrolyte Structure and Salt Concentration on the Porous Architecture of Self-assembled DNA/Polycations Macroporous Multilayer Thin Films

YU Yong-Jiang, WEI Guang-Yao, ZHOU Ying, LI Wen-Chao, LI Qiu-Shun, WANG Jun-Nan, YAO Wei-Guo, DONG Wen-Fei

2013, 34(11):  2644-2649.  doi:10.7503/cjcu20130165

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Two different polycations, one is the strong polyelectrolyte of poly(diallyldimethylammonium chloride)(PDDA) and the other is the weak one of polyallylamine hydrochloride(PAH), were utilized to form multilayer thin films with deoxyribonucleic acid(DNA). Atomic force microscopy(AFM) and ultraviolet-visible spectroscopy(UV-Vis) were used to investigate the effects of polycation structure and salt concentration on the macroporous architecture and growing behaviors. The results demonstrate that in the case of DNA/PDDA multilayer thin films, salt concentration effect plays an important role on the formation of macroporous structure; however, in the case of DNA/PAH multilayer thin films, there is no porous structure even at higher salt concentration in the DNA or PAH solution. This is mainly due to the inherent weak electrolyte characteristics of PAH. Therefore, in addition to the effects of molecular weight mismatch and persistent length mismatch as-mentioned, the effects of salt concentration and polyelectrolyte structure are the key factors for controlling the formation of the macroporous architectures.



Polymer Chemistry

Preparations and Properties of the Phosphorus-containing Polyimide Fibers

DING Xiang, QIU Xue-Peng, MA Xiao-Ye, LI Guo-Min, GAO Lian-Xun

2013, 34(11):  2650-2654.  doi:10.7503/cjcu20130785

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The phosphorus-containing diamine compound, bis(4-aminophenoxy)-phenyl phosphine oxide(DAPOPO) was synthesized. The solutions of polyamic acid(PAA) prepared from DAPOPO and 4,4'-oxydianiline(ODA) with pyromellitic dianhydride(PMDA) and 3,3',4,4'-biphenyl tertracarboxylic dianhydride(BPDA) were used for PAA fiber spinning with two-step process by dry-jet wet spinning. The polyimide(PI) fibers were obtained from PAA fibers by the process of the thermal imidization and hot dra-wing. The morphologies, mechanical properties, thermal properties and flame retardant properties of PI fibers were systematically investigated by the scanning electron microscopy(SEM), fiber mechanical property tester, thermogravimetric analyzer(TGA) and limiting oxygen index(LOI) value tester, respectively. The results indicate that thermal stability of the PI fibers is obviously enhanced with increasing phosphorus content. The value of LOI is increased from 35 to 45. These powerfully demonstrate that the flame retardant of PI fibers have been significantly enhanced.



Synthesis and Properties of Soluble Polyimides Containing Naphthalene in the Side Chain

XIA Wei-Qing, XIAO Cai-Hua, JIA Xiao-Le, WANG Lei

2013, 34(11):  2655-2660.  doi:10.7503/cjcu20130732

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Two kinds of diamine monomers containing naphthalene were synthesized by 1-naphthaldehyde and 2,6-dimethylaniline or aniline. Novel polyimides containing naphthalene in the side chain were synthesized via a one-step high-temperature polycondensation. The structures of the polyimides were characterized by ¹H NMR and FTIR. The resultant polyimides show high glass transition temperature, excellent thermal stability, good solubility in common organic solvents and excellent mechanical properties. In addition, the polyimide fibers were prepared by electrospinning, and the films and fibers show good hydrophobic property.



Synthesis and Properties of Proton Exchange Membranes Based on Cross-linked Block Sulfonated Poly(arylene ether sulfone)s

TANG Wei-Fen, LING Ying, CHEN Shan-Shan, HU Zhao-Xia, CHEN Shou-Wen

2013, 34(11):  2661-2666.  doi:10.7503/cjcu20130695

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In order to improve the proton conductivity and stability of proton exchange membranes based on sulfonated poly(arylene ether sulfone)(SPAES), a series of cross-linked block SPAES membranes(cbSPAES) was prepared. The block SPAES copolymers were synthesized through block copolymerization and subsequently subjected to cross-linking modification in the presence of P₂O₅, where the cross-linking reaction taken place between -SO₃H groups and active hydrogen atoms attached to the polymer backbones. Proton conductivity of the cbSPAES membranes were obtained by electrochemical impedance spectroscopy(EIS), dimensional and hydrolytic stabilities were evaluated by the membrane size changes in the in-plane/through-plane directions and accelerating aging test in water, respectively. The results indicate: (1) cbSPAES membranes have obvious better dimensional and hydrolytic stabilities than SPAES membranes; (2) at the same cross-linking degree, water uptakes and proton conductivities of cbSPAES membranes increase with the increase in repeat units of sulfonated moieties. For example, the membrane of cbSPAES(30/10)-10 exhibits water uptake of 65%, size changes in the in-plane/through-plane directions of 0.16/0.18 and proton conductivity of 163 mS/cm in water at 60 ℃.



Preparation of PVA/DTC Nanofibers and Their Adsorption Performance of Lead Ion

ZHANG Qian, XIA Ke, LIU Li, LIU You-Chang, ZHANG Cui, LIU Xuan, XU Huan, CHEN Shi-Jin, CHEN Ji-Da

2013, 34(11):  2667-2673.  doi:10.7503/cjcu20130693

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Polyvinyl alcohol/polyetherimide(PVA/PEI) nanofibers were fabricated by electrospinning. Subsequently, the nanofibers were functionalized with carbon disulfide to form polyvinyl alcohol/dithiocarbamates(PVA/DTC) nanofibers with higher adsorption capacity for heavy metal ions. The adsorption performance of PVA/DTC nanofibers for lead as well as the crosslinking and functionalization reaction PVA/PEI were investigated. The experimental data show that the fibers have diameters in hundreds nanometers and good appea-rance. The microstructure of nanofiber almost kept unchanged after crosslinking process and functionalization. The PVA/DTC nanofibers with good regeneration power possess much rapid adsorption and higher adsorption capacity. It is potential adsorption material for efficently removal heavy metal ions from waste water.



Preparation of Modified Expandable Graphite and Its Flame Retardant Application in Rigid Polyurethane Foam

XU Dong-Mei, DING Fei, HAO Jian-Wei, DU Jian-Xin

2013, 34(11):  2674-2680.  doi:10.7503/cjcu20130686

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The modified expandable graphite(MEG) was prepared by grafting silane coupling agent and then loading boric acid on the surface of expandable graphite(EG), then investigate the flame retardant application of MEG in rigid polyurethane foam(RPUF). The morphology, elemental composition and structure, properties of MEG were characterized by scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared(FTIR), expansion test and thermogravimetric analysis(TG), the thermal stability and combustion behaviour of RPUF/MEG were investigated by TG, limiting oxygen index(LOI) test and cone calorimeter. The results show that boric silicon compound is deposited on the surface of EG as ceramic precursor. The expansion char layer of MEG and RPUF/MEG become denser, and the mount of residual char of MEG and RPUF/MEG are increased by 8.7% and 3.7% at 800 ℃, respectively. Compare to RPUF/EG, the LOI of RPUF/MEG system is somewhat increased, the peak value of heat release is reduced by 10%, smoke production rate and CO release rate are also decreased significantly. Improving of RPUF/MEG system in flame retardation is related to participation of boric silicon ceramic precursor which promotes the effect of each component and enhanced the barrier property of char layer.