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10 July 2016, Volume 37 Issue 7

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Cover and Content of Chemical Journal of Chinese Universities Vol.37 No.7(2016)

2016, 37(7):  0-0. 

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Letter

New Tanshinone IIA Delivery System Using Chitosan Nanomicelles of Small Size^†

LI Hong, DU Libo, ZHANG Han, ZHAO Yuming, LIU Yang

2016, 37(7):  1229-1231.  doi:10.7503/cjcu20160288

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It is still a great challenge to design and synthesize ultra-small chitosan nanoparticles for encapsulating highly hydrophobic neuroprotectants, such as anti-stroke drug tanshinone IIA. To address the issue, a new amphiphilic polymeric micelle system(i.e. CS-g-TPS) was synthesized by covalent linking of D-α-tocopherol succinic acid ester with hydroxylethyl-chitosan in a green and effective approach. The results showed that the obtained CS-g-TPS can be self-assembled into ultra-small nanoparticles by hydrophilic-hydrophobic interaction in aqueous solution, which can be effectively loaded with tanshinone IIA. The particle size and morphology were characterized by scanning electron microscopy(SEM) and dynamic light scattering(DLS), respectively. Bioassays of cell viability and drug uptake further revealed that the CS-g-TPS/tanshinone IIA delivery system could achieve excellent in vitro biocompatibility, as well as high cellular uptake efficiency. It indicated that CS-g-TPS might be a promising drug delivery system for water insoluble neuroprotectant with the characteristics of high biosafety.



Articles: Inorganic Chemistry

Performance of Nano-porous β-Li₃PS₄ Prepared by Solvent Removing Method^†

PAN Yizhen, LI Yujie, CHEN Yimin, ZHENG Chunman

2016, 37(7):  1232-1238.  doi:10.7503/cjcu20160333

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Room temperature-stable and highly ionic conductive crystal electrolyte β-Li₃PS₄ was fabricated via solvent-removing method using Li₂S and P₂S₅ as reactants, tetrahydrofuran as solvent. Then β-Li₃PS₄ was analyzed through X-ray diffraction, differential thermal analysis and thermogravimetry analysis, Raman spectrometry, N₂ adsorption-desorption analysis and electrochemical impedance spectroscopy. Effects of heat treatment temperature on solvent removing, crystallization, specific surface area, porosity, and ionic conductivity were investigated. The results show that solvent-removing method successfully stabilizes β-Li₃PS₄ at room temperature. When heated at 160 ℃, Li₃PS₄ reaches its highest ionic conductivity, 7.44×10^-6 S/cm. During the heating treatment, tetrahydrofuran solvent was removed in 3 stages, generating numerous nanopores at both surface and interior of the Li₃PS₄ particles. Those nanopores increase surface energy, which helps new phase nucleate, expedites crystalline transition, reduces phase transition temperature, and stabilizes β-Li₃PS₄ to room temperature.



Preparation of GSH-Modified Au Nanorods and Their Interaction with Copper Ions^†

ZHANG Lingyue, CHI Yanan, SHAN Guiye, CHEN Yanwei, LIU Na

2016, 37(7):  1239-1244.  doi:10.7503/cjcu20160406

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Au nanorods(Au NRs) modified by glutathione(GSH) were prepared. Based on the dependence of localized surface plasmon resonance(LSPR) peak shift on their arrangement, the structure and optical properties of GSH-modified Au NRs was studied at different pH conditions. At pH=5, some metal ions were chosen to detect the effect of their interaction with GSH-Au NRs on the LSPR peak of Au NRs. The results demonstrate that Cu²⁺ can obviously induce red shift of LSPR peak comparing with other metal ions. The reason is the rearrangement of Au NRs induced by Cu²⁺. Meanwhile, the photothermal experiment for pure Au NRs and GSH-Au NRs with copper ions were carried out to detect the effect of copper ions on optical properties of Au NRs. Comparing with pure Au NRs, GSH-Au NRs with copper ions decreased the efficiency of phothothermal conversion. During photothermalcoversion process, copper maybe capture the electron of Au NRs and decrease the efficiency of nonirradiation. So, Au NRs modified by GSH show the selective detection for Cu²⁺. The results here maybe provide a new method for detection of heavy metal ions.



Effect of Tb³⁺ on the Stability of Ovalbumin^†

SONG Zhen, DONG Jinlong, REN Yuehong, YUAN Wen, ZHANG Caifeng, YANG Binsheng

2016, 37(7):  1245-1249.  doi:10.7503/cjcu20160259

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The binding properties of Tb³⁺ with ovalbumin were measured by fluorescence spectra at room temperature in pH=7.4, 10 mmol/L 4-(2-hydroxyethyl)-1-piperazinecthanesulfonic acid(Hepes). The effect of Tb³⁺ on the hydrophobic region of ovalbumin was measured by hydrophobic probe 2-p-toluidino-6-naphthalenesalfonic acid(TNS). The effects of Ca²⁺ and Tb³⁺ on the stability of ovalbumin were analyzed by chemical unfolding methods. The results suggested that ovalbumin can form 1∶2 complexes with Tb³⁺. The binding of Tb³⁺ increased the hydrophobic surface of ovalbumin, and the fluorescence intensity of TNS increased. The unfolding curves of ovalbumin showed two transition, N?I and I?U. Ca²⁺ can increase the stability of transition I?U and Tb³⁺ can increase the stability of transitions N?I and I?U.



Synthesis and Characterization of Novel Ni(Ⅱ) Metal-organic Frameworks with Helical Crystal Structure^†

ZHAO Lun, BAI Helong, SUN Erjun, WANG Xiaofeng, WANG Zichen

2016, 37(7):  1250-1256.  doi:10.7503/cjcu20150903

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The multidenate 4,4'-(phenylazanediyl)dibenzoic acid(H₂L) ligand and nickel(Ⅱ) ions reacted with 1,3-bis(imidazol-l-yl)benzene(bib) or 4,4-bipyridine or 1,4-bis[4-(1H-imidazol-l-yl)benzyl]piperazine(bibpip) under the solvothermal reactions, three new metal-organic frameworks with helical structure, namely{[Ni₂L₂(bib)₂·2H₂O]·5H₂O}_n(1), [Ni(HL)₂(bpy)]_n(2) and {[Ni₂L₂(bibpip)₂·2H₂O]·6H₂O}_n(3), were presented along with an analysis of the structural features by single-crystal X-ray diffraction. Complexes 1—3 were also characterized by FTIR spectroscopy, elemental analyses, thermal analysis and power X-ray diffraction(PXRD). The results showed that the complex 1 crystallizes in the monoclinic space group C2/c, exhibited two-dimensional(2D) layer with {4²·6⁵·8} topology structure; complex 2 crystallizes in the orthorhombic space group Fdd2, gave a 3D framework with {4⁸·5⁴·6³} topology structure; complex 3 exhibits a 5-fold interpenetrating 3D framework with a {4⁴·6²} topology.



Analytical Chemistry

Study on Apoptosis Process of CaSki via Fast Line-scanning Raman Imaging^†

ZHANG Jinliang, MA Xin, XU Mengxi, ZONG Cheng, REN Bin

2016, 37(7):  1257-1261.  doi:10.7503/cjcu20160265

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Cisplatin-induced apoptosis of CaSki cell was studied via Raman imaging technique. Fast line-scanning Raman imaging method could reveal the high temporal and spatial information of biomolecules including cytochrome c, protein and lipid during the apoptosis process. The results indicate that the relative intensity of cytochrome c to protein(I₇₅₀/I₁₆₆₀) could reflect the stage of apoptosis. Compared with the traditional methylthiazoletetrazolium(MTT) method, Raman imaging could investigate the apoptosis of single living cell at a much higher temporal resolution and provide the molecular fingerprint information for revealing the cell-drug interaction.



Quantitative Multi-targeted Imaging of Metastatic Colorectal Cancer Cells Using Aptamer Probes in Combination^†

LI Wanming, FANG Jin

2016, 37(7):  1262-1268.  doi:10.7503/cjcu20160254

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We developed seven aptamer probes towards metastatic colorectal cancer cells by conjugating the aptamers to quantum dots(QD605) for multi-targeted cancer cell imaging. The results of competitive assay showed that the seven aptamers could recognize their individual targets on the same cell without any mutual interference, revealing that they may be applied in combination for multi-target cancer cell imaging. The results of quantitative assay of the fluorescence images showed that compared with a single probe, the seven probes in combination can significantly increase the fluorescent intensity on the cell surface, and the detection rate of positive cells increased significantly, resulting in a higher detection sensitivity. Further, the probes were used to detect several colorectal cancer cell lines using flow cytometry. The results showed that seven probes used in combination could effectively evaluate colorectal cancer metastatic potential. This study demonstrated that usage of multiple aptamer probes in combination could effectively improve the sensitivity and accuracy of target imaging which provides a novel approach for targeted diagnosis of colorectal cancer.



Detection of Copper Ion Based on the Interaction Between DNA Molecules and Copper Ions^†

LI Min, KONG Huifang, GUO Zhihui

2016, 37(7):  1269-1275.  doi:10.7503/cjcu20160116

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Copper ion(Cu²⁺) is one of the essential trace elements of human, which plays an important role in life. However, excessive amounts of copper ions may cause serious damage to health. In this work, Cu²⁺ ions were determined by differential pulse voltammetry(DPV) based on its concentration on DNA modified electrode due to the complexation of Cu²⁺ ions with the base of DNA. Furthermore, because ethylenediaminetetraacetic acid(EDTA) shows stronger complexing ability to Cu²⁺ ions than DNA, Cu²⁺ concentrated on DNA modified electrode can be eluted with EDTA. Thus, the modified electrode was reusable. The results showed that under optimum conditions, the relative reduction current(I-I₀) was linear with the concentration of copper ions in the range of 2.0×10^-6—1.0×10^-5 mol/L and 2.0×10^-5—1.0×10^-4 mol/L. The proposed electrochemical sensor for Cu²⁺ ions was simple, stable and reusable.



Simultaneous Determination of 7 Components in Functional Food for Anti-hangover and Hepatoprotection by Capillary Electrophoresis^†

ZOU Haimin, ZHOU Chen, SUN Chengjun, LI Yongxin, YANG Xiaosong, WEN Jun, ZENG Hongyan

2016, 37(7):  1276-1281.  doi:10.7503/cjcu20150980

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A rapid method of micellar electrokinetic capillary electrophoresis(CE) coupled with diode array detection was developed for simultaneous determination of catechin, epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, dihydromyricetin and glycyrrhizic acid in functional food for anti-hangover and hepatoprotection. The parameters of capillary electrophoresis, including buffer concentration, concentration of sodium dodecyl sulfate(SDS), volume ratio of acetonitrile, and pH of the buffer, were optimized with orthogonal design. Under the optimal analytical conditions, the peak area of each analyte and its concentration had a good correlation within the linear range(r≥0.9989). Limit of detection(LOD) and quantification(LOQ) of the method were in the range of 0.26—2.22 μg/g(S/N=3) and 0.87—7.39 μg/g(S/N=10), respectively. The intra- and inter-day relative standard deviations(RSDs) of the mixed standard solution were 1.3%—2.5% and 1.9%—3.9%, respectively. While the spiked recoveries of the analytes were 91.4%—104.9% and the RSDs of the spiked samples were 1.4%—3.2%. The method of capillary electrophoresis for determination of the 7 components in functional food for anti-hangover and hepatoprotection was proposed in this study and could achieve baseline separation for all the target components within 8 min. The results show that the method could meet the requirement for routine analysis and quality control and evaluation.



Organic Chemistry

Citrinin Derivatives from Marine-derived Fungus Penicillim Grisefulvum and Antibacterial Activity^†

GAO Tong, CAI Siyuan, XU Lanlan, CAO Fei, ZHU Huajie

2016, 37(7):  1282-1286.  doi:10.7503/cjcu20160315

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The marine fungus Penicillim grisefulvum was cultivated with 43 d at 28 ℃, bioassay-guide fractionation of the marine fungus Penicillim grisefulvum led to the isolation of three citrinin derivatives(1—3), which were separated by silica gel column chromatography, C₁₈ column chromatography, Sephadex LH-20, and semi-preparative HPLC. Based on the HR-ESI-MS, 1D and 2D NMR, compounds 1—3 were assigned as 7-methyl-penicitrinone A(1), citrinin(2) and penicitrinone A(3), respectively. The absolute configuration of compound 1 was determined by comparision of experimental and calculated electronic cicular dichroism(ECD) data. Compound 1 displayed strong antibacterial activity against Vibrio parahemolyticus(MIC=0.8 μmol/L), which was stronger than the positive control of ciprofloxacin(MIC=1.3 μmol/L).



Design, Sythesis and Biological Evaluation of Polyphenol-α-helical Peptide Conjugates as Potent HIV-1 Fusion Inhibitors^†

CHENG Siqi, LIANG Guodong, JIANG Xifeng, WANG Chao, LIU Keliang

2016, 37(7):  1287-1292.  doi:10.7503/cjcu20160295

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De novo-designed peptide sequences with an α-helical conformation can prevent fusogenic gp41 six-helical bundle(6HB) formation by specifically interacting with the Human Immunodificiency virus type 1(HIV-1) gp41 N-terminal heptad repeat(NHR) region, thus inhibiting HIV-1-cell membrane fusion. Meanwhile, polyphenols, such as hydroxytyrosol(HT) and (-)-epigallocatechin gallate(EGCG), are a major group of natural compounds with a broad spectrum of antiviral activity. In this paper, mHT were designed and obtained based on 3,4-dihydroxymethylacetic acid. Then, mHT and other bioactive polyphenols, were covalently conjugated to a certain α-helical peptide through specific linkers with different lengths and flexibilities. These conjugates interacted with the gp41 NHR region and exhibited promising fusion inhibitory activity, with IC₅₀ values in the low micromolar range. This study provides a promising strategy for the development of fusion inhibitors against viruses with class I fusion proteins.



Design and Synthesis of Pyrimido[4, 5-d] pyrimidin-4(3H)-ones as Selective L3MBTL1 Binders

ZHOU Hao, CHE Xin, PENG Li, WANG Na, BAI Xu

2016, 37(7):  1293-1301.  doi:10.7503/cjcu20160203

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Histone methylation is a key epigenetic mark, and its deregulation is linked to many diseases. Malignant brain tumor(MBT) domain protein is one of the proteins that could read methylated lysine(Kme) of histones. Lethal 3 malignant brain tumor 1(L3MBTL1), a member of the MBT family, is related to transcriptional repression, erythroid differentiation and tumor formation. Developing a potent and selective inhibitor of L3MBTL1 can help explain the regulatory mechanisms and validate its drugability. UNC669 was reported as the first small molecule ligands for a methyl-lysine binding domain. A series of compounds was synthesized by replacing its aromatic component with pyrimido[4, 5-d] pyrimidin-4(3H)-ones. Screening these compounds by AlphaScreen^® led to a hit compound 8a(IC₅₀=1.21 μmol/L). Exploring 5-position of compound 8a generated three selective and potent L3MBTL1 binders(compounds 8g, 8o and 8p), which showed no significant activity against the other Kme reader proteins in the panel, even its closely related MBT containing proteins, L3MBTL3.



Tripeptide Containing Selenium with Glutathione Peroxidase Activity^†

YIN Juxin, LI Zuhong, MU Ying, LÜ Shaowu, LUO Guimin

2016, 37(7):  1302-1306.  doi:10.7503/cjcu20160101

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Six selenium-containing tripeptides(QUW, QWU, WQU, WUQ, UWQ and UQW) were synthesized by solid-phase synthesis technology based on the catalytic triad of native glutathione peroxidase(GPx). The GPx activities and the kinetics of the tripeptide were determined by the enzyme coupling method. The effects of tripeptide on HepG2 cells growth and migration were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay, wound assay and Western blot method. The results showed that the GPx activity of the tripeptide with U at the amino terminal was higher than that of U at the middle position or the carboxyl terminal. Among the six tripeptide, the activity of UWQ catalyzed by glutathione(GSH) reduced by hydrogen peroxide(H₂O₂) was higher than those of other tripeptides, and its catalytic mechanism was Ping-Pong mechanism. UWQ can dosedependently discrease migration speed of HepG2 cells to exercise, and reduce the invasion and metastasis of HepG2 cells.



Synthesis and Anti-HBV Activity Evaluation of the Galactopyranosyl Derivatives of MTS Based on Click Reaction^†

YUAN Jie, LIU Qingchuan, XU Guangcan, LIANG Guangyi, XU Bixue

2016, 37(7):  1307-1319.  doi:10.7503/cjcu20160098

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Matijin-Su [N-(N-benzoyl-L-phenylalanyl)-O-acetyl-L-phenylalanol, MTS], a dipeptide derivative, was isolated from a Chinese ethnic drug Matijin(Dichondra repens Forst.) which has been widely used in the treatment of chronic liver disease as folk medicine in China. A series of MTS derivatives with anti-hepatitis B virus(HBV) activitiy was synthesized by structural modification of MTS. One of MTS derivatives named “Tyrophentide” had been finished pre-clinical research and has been approved to do clinical study of phase Ⅰ by China Food and Drug Administration(CFDA). The preliminary pharmacokinetic experiments showed that it was widely distributed in many organs, and the concentration in liver was low. To improve the concentration in liver lesion tissue and increase the anti-HBV activity of MTS derivatives, a series of hepatic targeting galactopyranosyl derivatives of MTS 15a—15f was designed according to asialoglycoprotein receptor(ASGP-R) mediation and synthesized. Starting from unexpensive and commercially available galactose and triethylene glycol, the glycosyl donor with azide linker was achieved via acetylation, glycosylation and azidation reaction. At the same time, propargylated MTS derivatives using L-phenylalaninol, L-tyrosine methyl ester hydrochloride, benzoic acid and its derivatives as the starting materials were prepared by acylation, hydrolysis, alkylation, condensation reactions and so on. Then compounds 15a—15f with a 1,2,3-triazole unit were obtained from “click” chemistry reaction using copper(Ⅰ) catalyst in high yield(over 85%), which were deacetylated in the 0.41 mol/L solution of sodium methoxide to give target compounds. The structures of target compounds were confirmed by ¹H NMR, ¹³C NMR, ¹H-¹H COSY, HMQC, DEPT and ESI-MS. The anti-HBV activities of target compounds were evaluated in HepG2 2.2.15 cells. The screening results showed that all target compounds had inhibitory effect on HBV DNA replication in HepG2 2.2.15 cells. Compound 15f showed inhibition rate anti-HBV activity of 83% at 50 μg/mL and could be worthy of further research.



Conservative and Variability of the Important Functional Sites in a Laccase from Bacillus Subtilis^†

JIAO Jing, YANG Xue, JIN Lanna, GAO Jian, ZHOU Yang, XIAO Yazhong, ZHANG Yingjiu

2016, 37(7):  1320-1327.  doi:10.7503/cjcu20160092

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A laccase from Bacillus subtilis has more than 96% residue identity to most other bacterial laccases, but has lower catalytic activity. Four mutant laccases were designed and their catalytic properties and functions were investigated. The results demonstrated that residue H155 was particularly essential for the catalytic activity of this laccase, and was one of the key residues in the second conserved region of laccases. Replacement of this residue reduced the oxidation-reduction potential and the catalytic activity of the laccase, and also reduces its thermal or pH stability, and caused a shift of its optimum pH from 5.0 to 4.0. Conservation of residues A158 and I224 in non-conserved region of the laccase was also advantageous for the catalysis of the laccase. A158 was conducive to the electron transport in enzymatic oxidation process, while I224 was appropriate to make the substrate into the mononuclear center of the laccase. S210G mutation enhanced the catalytic efficiency of the laccase perhaps by increasing of the flexibility of the pro-rich loop adjacent to the entrance of the substrate channel of this laccase. The laccase in this study decolorized indigo dyes such as indigo carmine more effectively than triphenylmethane dyes such as crystal violet, azo dyes such as methyl red or Congo red, and anthraquinone dyes such as Remazol Brilliant Blue R(RBBR), indicated that the laccase in this study had certain substrate selectivity. These results would provide some insights into the relationship between the structure and function of bacterial laccases.



Preparation of Oxime Cesium Salts and Its Function as Cleaving Agents in Peptide Synthesis^†

ZONG Liang, DONG Junjun, CHEN Jing, LI Jian, SUI Shaohui, WEI Yifei, ZHANG Ming

2016, 37(7):  1328-1334.  doi:10.7503/cjcu20160062

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This paper aimed at preparation of side chain protected peptides. Modified Wang resin loaded with 2-bromoacetyl linker was selected for syntheses of three kinds of model peptides by the method of solid phase peptide synthesis(SPPS). These model peptides were used to examine the cleave function of some oximates with alkalescence and strong nucleophilicity. Five oxime cesium salts with different structures were designed and synthesized for the cleavage of model peptides from the resin. The optimal cleave conditions of 2-pyridine aldoxime cesium which had the best performance in the cleavage, was studied in detail. The experimental results showed that model peptides with side chain fully protected could be obtained with high yields in mild conditions using oxime cesium salts as cleave reagents in SPPS.



Preparation, Characterization and Immunological Activity Evaluation of Low Anticoagulant Heparin Oligosaccharides^†

ZHANG Xiao, SHAN Xindi, ZHAO Xiaoliang, LI Guoyun, WANG Xiaojiang, CAI Chao, HAO Jiejie, YU Guangli

2016, 37(7):  1335-1341.  doi:10.7503/cjcu20150863

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Anticoagulant activities limit applications of heparin and enoxaparin sodium in immune-promoting activity. A novel and natural low anticoagulant heparin(LAH) was purified from crude porcine intestinal. In this work, oligosaccharide of LAH(BE-LAH) was prepared by benzyl ester alkaline hydrolysis. The molecular distribution and chemical structure of BE-LAH were determined based on combination technologies including polyacrylamide gel electrophoresis(PAGE), high performance gel permeation chromatography(HPGPC)-multi angel laser light scattering(MALLs), nuclear magnetic resonance(NMR) and liquid chromatography-mass spectrum(LC-MS). Meanwhile, the anticoagulant activities were evaluated by measuring the inhibitory activities on coagulation factor Xa(FXa) and thrombin(FⅡa), while the immunological activities were evaluated by its modulation effects on phagocytic ability and NO release of RAW 264.7 cells. The results demonstrated that BE-LAH was composed of fragments from dp2 to dp22 with an average molecular weight of 5300. Expectedly, BE-LAH showed no anticoagulant activity, but remarkable immune-promoting activity. A low anticoagulant heparin oligosaccharide was prepared and promised as an excellent immunoenhancer.



Physical Chemistry

Cluster Properties of Au₁₉Pt and Selective Hydrogenation Mechanism of Cinnamaldehyde on Au₁₉Pt Cluster Surface^†

CAO Yongyong, JIANG Junhui, NI Zheming, XIA Shengjie, QIAN Mengdan, XUE Jilong

2016, 37(7):  1342-1350.  doi:10.7503/cjcu20160314

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Structural stability, thermodynamic stability and chemical reactivity of the bimetallic Au₁₉Pt clusters were investigated based on the framework of the relativistic density functional theory. It was calculated that Au₁₉Pt-V cluster was chemically more active than Au₁₉Pt-S and Au₁₉Pt-E clusters but thermodynamically less stable. To explore the most stable adsorption configuration, the adsorption behavior of a cinnamaldehyde on three types of bimetallic Au₁₉Pt cluster was studied via analyzing the adsorption energy and Mulliken charge. The calculation results indicate that a cinnamaldehyde molecule is preferably adsorbed on Pt site in Au₁₉Pt-V cluster with C=C, in which the adsorption configuration is the most stable. In that condition, the adsorption energy and the amount of charge transfer are maximum. Moreover, 6 possible mechanisms were investigated of three kinds of selective hydrogenation reaction(1,2-additive reaction, 3,4-additive reaction and 1,4-conjugate additive reaction) of cinnamaldehyde on Au₁₉Pt-V cluster, on the basis of the most stable adsorption configuration. Compared with the reaction energy, activation energy and configuration change of each elementary steps, it suggests that the most favorable way of the cinnamaldehyde on the Au₁₉Pt-V cluster would be through 3,4-additive reaction(mechanism C). The specific reaction pathway involved a C3 atom preferentially hydrogenating to generate MS3 intermediate, another H atom added to intermediate to take shape C4—H bond. Then the final product phenylpropyl aldehyde is forming through the transition state TS34.



Shape Memory Polymer Surface with Tunable Microstructure and Adhesion^†

LÜ Tong, CHENG Zhongjun, LAI Hua, ZHANG Enshuang, LIU Yuyan

2016, 37(7):  1351-1356.  doi:10.7503/cjcu20160181

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A low adhesive superhydrophobic surface with shape memory microstructures was prepared by the template method. It was found that under the external pressure, the surface would lose the superhydrophobicity for the destroyed microstructures, and meanwhile, the surface became high adhesive. After heating the surface at 120 ℃, both surface microstructures and the low adhesive superhydrophobicity can be recovered. The results indicate that the adhesive property can be controlled reversibly by controlling the surface microstructures. Different microstructures results in different wetting states, as a result, the surface shows different adhsions. On the original surface, water droplet resides in the low adhesive Cassie state, while on the crushed surface, the droplet resides in the high adhesive Wenzel state.



Infrared Ray Assisted Microwave Synthesis of Graphitic Carbon Nitride and Its Nitrogen Photofixation Ability^†

CAO Yuhui, TONG Yufei, ZHANG Jian, LI Fayun, FAN Zhiping, BAI Jin, MAO Wei, HU Shaozheng

2016, 37(7):  1357-1363.  doi:10.7503/cjcu20160148

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A convenient infrared ray assisted microwave method was used to synthesize graphitic carbon nitride(g-C₃N₄) with outstanding nitrogen photofixation ability under visible light. X-ray diffraction(XRD), N₂ adsorption, UV-Vis spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM), N₂-temperature programmed desorption(TPD), electron paramagnetic resonance(EPR), photoluminescence spectroscopy(PL) and photocurrent measurements were used to characterize the prepared catalysts. The results indicate that microwave treatment can form many irregular pores in the as-prepared g-C₃N₄, which causes the increased surface area. More importantly, microwave treatment causes the formation of many nitrogen vacancies in the as-prepared g-C₃N₄. These nitrogen vacancies not only serve as active sites to adsorb and activate N₂ molecules but also promote the interfacial charge transfer from catalysts to N₂ molecules and the separation rate of electrons-hole pairs, thus significantly improving the nitrogen photofixation ability. The higher nitrogen vacancy concentration of g-C₃N₄ prepared by infrared ray assisted microwave treatment causes the more chemisorption sites, leading to the higher nitrogen photofixation performance. This method is simple and convenient, and is suitable for large-scale production of g-C₃N₄ catalyst.



Effect of Metallic Impurities in the Electroplating Solution on Nickel Coatings^†

TANG Xuqing, REN Xiubin, LU Haiyan, LIN Haibo, WANG Chaonan, LIU Honghong, LIU Shouxin

2016, 37(7):  1364-1371.  doi:10.7503/cjcu20160140

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To study the influence of impurities on the coating quality, 2 g/L of Co²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Cd²⁺, Zn²⁺ were introduced into the nickel plating solution, respectively. The results of X-ray diffraction(XRD) revealed that the obtained nickel coatings were of different growth orientation. The results of scanning electron microscopy(SEM) showed that the presence of metallic impurities made coating grain size smaller, different metallic impurities made different influence, then the brightness and density of the obtained coatings had great difference. Regularity of electrochemical behavior of electroplating solution with different metallic impurities was investigated by catholic polarization, chronopotentiometry and electrochemical impedance spectroscopy. Through the concentration gradient experiment, corrosion experiment, heat cycle and high temperature experiments, the critical concentrations of metallic impurities were guaranteed to obtain high quality Ni coatings for different use.



PdZn Alloy Nanoparticles Epitaxial Growth on ZnO Nanowires for Methanol Steam Reforming^†

LIU Jiaxin, SONG Yian, HUANG Yudong

2016, 37(7):  1372-1379.  doi:10.7503/cjcu20160061

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ZnO nanowires (NWs) supported Pd catalysts were prepared by modified deposition-precipitation method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscope (HAADF-STEM). The effects of Pd loading and reduction temperature on the formation of PdZn were investigated. The results showed that the high CO selectivity of 2.1%Pd/ZnO NW catalyst after reduced at 400 ℃ is due to the formation of Pd_xZn_y(x>y) alloy. Increasing of Pd loading or reduction temperature is favorable for the transformation of Pd_xZn_y(x>y) to PdZn alloy which can inhibit CO formation. By a modified wet chemistry method and apt post-synthesis treatment, we have been able to grow PdZn alloy nanoparticles epitaxially onto the {10\begin{array}{c}\overline{1}\end{array}0} nanofacets of the ZnO NWs. It showed better stability than PdZn supported on commercial ZnO powders in long term reaction. The methanol conversion at 300 ℃ over Pd/ZnO NW remained constant for about 40 h without obviously deactivation. On the contrary, the methanol conversion over Pd/ZnO powders catalyst gradually decreased with time on stream by more than 30%. The better stability of Pd/ZnO NW catalysts is due to the highly stable ZnO NWs primarily enclosed by the low-energy {10\begin{array}{c}\overline{1}\end{array}0} surfaces and the epitaxial relationships between PdZn nanoparticles and ZnO NWs support.



Effect of Activated Carbon Surface Chemistry on the Properties of Cu Particles and the Catalytic Performance for Oxidative Carbonylation of Methanol^†

ZHANG Guoqiang, ZHENG Huayan, HAO Zhiqiang, LI Zhong

2016, 37(7):  1380-1389.  doi:10.7503/cjcu20150995

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Activated carbon(AC) was thermal treated under nitrogen and ammonia atmosphere, respectively, and used as a support to prepare Cu/AC catalyst by impregnation-calcination method. The influence of AC surface chemistry on the catalyst composition and Cu species particle size as well as the catalytic performace for oxidative carbonylation of methanol has been investigated. AC supports and their corresponding Cu/AC catalysts were characterized intensively by BET, XPS, XRD, H₂-TPR and TEM. The results indicate that the removal of most carboxylic groups by thermal treatment at 600 ℃ under nitrogen atmosphere can improve the Cu species dispersion and reduce the Cu species particle size. However, with further elevating the temperature to 800 ℃, part of lactones, carboxylic anhydrides, phenol and ether groups were removed that lead to the Cu species agglomeration and sintering. Moreover, the decreased AC surface oxygen containing groups has weakened the precursor-support interaction and promoted the reduction of Cu²⁺ to Cu⁺ or Cu⁰. Thermal treatment of AC under ammonia atmosphere results in that more surface oxygen containing groups were removed compared with nitrogen atmosphere. But nitrogen containing groups including pyridinic N(N-6), pyrrole nitrogen(pyrrolic-N) and quaternary nitrogen(N-Q) were introduced at the same time, which was conducive to the Cu species dispersion and reduction of particle size. Besides, the increased surface nitrogen containing groups has enhanced the precursor-support interaction and supressed the reduction of Cu²⁺ to Cu⁺ or Cu⁰. The evaluation result reveals that the catalytic activity of the catalyst varies with the change of the particle size of Cu species. As Cu supported on AC thermal treated at 800 ℃ under ammonia atmosphere, the catalyst shows the optimum catalytic performance, which is ascribed to the smallest Cu species particle size(6.3 nm). The conversion of methanol, space-time yield and selectivity of dimethyl carbonate(DMC) are 9.6%, 278.7 mg·g^-1·h^-1 and 68.3%, respectively.



Effect of Vibrational Excitation on the Stereodynamics of Reaction O+DCl⟶OD+Cl^†

XU Xuesong, LI Lei, JING Bo, YANG Kun

2016, 37(7):  1390-1394.  doi:10.7503/cjcu20150992

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The effects of vibrational excitation of reagent molecules on the stereo-dynamical properties of O+DCl?OD+Cl reaction were discussed via the quasi-classical trajectory(QCT) method. The polarization-dependent differential cross sections(PDDCSs), the polar distributions of P(θ_r) and P(φ_r) were calculated. The results show that the initial vibrational excitation of the reagent molecules has considerable influences on stereodynamics of the title reaction. When the reagent molecules are excited to higher vibrational levels the rotations of product molecule prefer to parallel to the scattering plane, in other words, "in-plane" mechanism.



Polymer Chemistry

Influence of Poly-octadecylacrylate-vinylacetate Comb-like Copolymers on Rheological and Crystallization Characteristics of Waxy Crude Oil^†

YANG Fei, XIAO Zuoqu, YAO Bo, LI Chuanxian, SUN Guangyu, YAN Kongyao

2016, 37(7):  1395-1401.  doi:10.7503/cjcu20160174

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The comb-like copolymers, which are used as pour point depressants(PPDs) for waxy crude oil, polyoctadecylacrylate(POA) and poly-octadecylacrylate-vinylacetate(POA-VA) were synthesized by solvent free-radical polymerizing method and characterized by ¹H NMR and gel permeation chromatography(GPC). The performance of comb-like polymers on waxy crude oil were investigated via pour point measurement, rheological test, differential scanning calorimetry method and polarized microscopic observation. The results show that the introduction of VA group controls the pour point depressing ability of POA. In particular, POA-VA-4[n(OA)∶n(VA)=3∶1] is the best PPD in optimizing rheological properties of the waxy crude oil. After the addition of 400 mg/kg POA-VA-4, compared with original waxy crude oil, the pour point of crude oil decreases by 22 ℃ and its average viscosity decreases by 51.45%. Based on the crystallization exothermic characteristics and wax crystal morphology of crude oils after the addition of POA and POA-VA, the mechanism of the effects of VA content on the performance of comb-like copolymer PPDs was proposed.



Fabrication of Natural Rubber/Chemically Reduced Graphene Oxide Nanocomposites and Nuclear Radiation Resistant Behavior^†

LIU Yaohua, LIN Yu, ZHANG Dongge, CHEN Chunlei, WU Guozhang, ZHANG Yan, LUAN Weiling

2016, 37(7):  1402-1407.  doi:10.7503/cjcu20160144

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Natural rubber(NR)/chemically reduced graphene oxide(RGO) nanocomposites were fabricated by latex mixing plus in situ reduction process. The transmission electron microscopy morphology shows that uniform dispersion of RGO with a few layers of stacked lamellar structure can be observed in the nano-composites. The effect of γ irradiation on the mechanical property and thermal stability of NR matrix by the incorporation of RGO was mainly investigated in detail. Compared to pure NR, the tensile strength increases from (22±1.4) MPa to (25±1.1) MPa and the thermal decomposition temperature of 50% mass loss(T₅₀) is increased by 6.4 ℃ for NR/RGO nanocomposites by the addition of 0.6% RGO before irradiation. After γ irradiation dose of 200 kGy, the tensile strength and T₅₀ of pure NR are decreased by 75% and 4.5 ℃, respectively. However, those of NR/RGO-0.6% nanocomposites are decreased only by 56% and 1.2 ℃, respectively. The radiation resistant mechanism of NR/RGO nanocomposites was also interpreted by electron paramagnetic resonance measurements. The results reveal that RGO can act as free radical scavenger, and the introduction of RGO to NR matrix exhibits much less amount of free radicals.



Preparation of Cross-linked Poly(aryl ether sulfone) Containing Pendant Quaternary Ammonium Groups for Anion Exchange Membrane^†

WANG Limei, DOU Liyan, XIN Peng

2016, 37(7):  1408-1414.  doi:10.7503/cjcu20150983

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Cross-linked anion exchange membranes(AEMs) for poly(aryl ether sulfone) bearing pendant quaternary ammonium groups were prepared by a simplified and environmental-friendly approach, which possess low swelling radio and high ion exchange capacity(IEC). The membrane test showed that the water uptake and swelling ratio reduce with increase of cross-linking degree. At 20 ℃, the cross-linking membranes show the ion conductivity above 0.045 S/cm and the tensile strength above 50.1 MPa, which indicates that the cross-linked film still keep good mechanical properties and higher ionic transmission ability under high IEC. Meanwhile, when the cross-linking degree increasing, the methanol barrier property of the membranes will enhance.