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10 April 2018, Volume 39 Issue 4

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Cover and Content of Chemical Journal of Chinese Universities Vol.39 No.4(2018)

2018, 39(4):  0-0. 

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Articles: Inorganic Chemistry

Preparation, Characterization and Electrochemical Properties of Mesoporous Biomass Carbon Derived from Corn Stalk^†

LI Yi, LI Chun, YU Kaifeng

2018, 39(4):  607-613.  doi:10.7503/cjcu20170824

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Corn stalk was used as raw material to prepare mesoporous biomass carbon using CaCl₂ as activator. The mesoporous biomass carbon was characterized by means of X-ray diffraction(XRD), Raman spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy(TEM) and N₂ adsorption-desorption analysis. The electrochemical properties of the mesoporous biomass carbon were analyzed and the formation mechanism of the mesoporous structure was explored. For the sample that calcined at 600 ℃, the specific surface area was 370.6 m²/g, the average pore size was 9.65 nm. When it was applied as the anode material of lithium ion battery, the discharge capacity of the sample was 783 mA·h/g at 0.2C rate after 100 cycles. Even at 10C rate, the electrode demonstrated an excellent high rate capability of 347 mA·h/g after 1000 cycles. The sample showed good rate performance and excellent cycle stability due to the large specific surface area, which can improve the permeability of electrolyte and increase the reactive sites. Moreover, the porous structure increased the free movement space for lithium ions and charges, which was conducive to the improvement of electrochemical performance.



Novel Os^Ⅱ -arene Complexes Based on Bipyridyl Derivative Ligands: Synthesis, Crystal Structure, Anticancer Activity and Interaction with DNA/BSA^†

HAO Yuanyuan, WU Qi, LI Ji, GE Chao, MA Chaoying, QIAN Yong, SU Zhi, LIU Hongke

2018, 39(4):  614-622.  doi:10.7503/cjcu20170634

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Five Os^Ⅱ-arene complexes(1-5) with bipyridyl derivative ligands were synthesized, where complexes 1-4 were obtained directly from the corresponding precursors, complex 5, however, was received through the anion-exchange experiment from complex 3, with Cl^- being replaced by P$F^{-}_{6}$. Single crystal structure analyses of complexes 1 and 5 revealed that both complexes adopted typical “piano-stool” conformations, where the “piano stool” consisted of the π-bond to the arene group, the Os-Cl and two Os-N bonds. The anticancer activities of the complexes towards variable cancer cells were determined by MTT assay. Complexes 1 and 3 exhibited moderate cytotoxicity towards human lung cancer cells(A549) than complexes 2 and 4. The interactions between the complexes with DNA/BSA were studied by utilization of UV-Vis, fluorescence and CD spectroscopy, and agarose gel electrophoresis. The results indicated that the synthesized complexes except complex 2 could effectively bind to DNA via intercalation. The fluorescence quenching was observed as complexes 1-4 were added into the BSA solution. The quenching constants(K_SV) of complexes 1-4 were larger than 10⁴ L/mol, suggesting that the quenching mechanism was static quenching. CD spectra illuminated that the complexes could induce intrinsic conformational changes in DNA. The mobility changes of the formⅠband were clearly observed in the presence of complexes 1 and 3 by gel electrophoresis assays.



Preparation of High Quality Ag₂S Quantum Dots with Near-Infrared Emission and Their Applications in Bioimaging^†

ZHANG Dan, YU Jinhai, LI Dongze, ZHOU Miao, ZHANG Ying

2018, 39(4):  623-628.  doi:10.7503/cjcu20170457

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A new method for preparing Ag₂S quantum dots(QDs) with near-infrared emission was presented by introducing the active sulfur precursor with alkylthiols as ligands. The high reactivity of sulfur precursor enables low temperature(< 120 ℃) syntheses, and produces Ag₂S QDs with small size. As-prepared samples were well characterized by means of UV-Vis-NIR absorption spectroscopy, transmission electron microscopy(TEM), X-ray powder diffraction(XRD) and energy-dispersive X-ray spectroscopy(EDX). As a result, the size of as-prepared Ag₂S QDs is tunable in a range from 1.7 nm to 3.5 nm with the inerease of reaction temperature from 50 ℃ to 120 ℃. Accordingly, the emission peak position of the Ag₂S QDs can be tuned from 700 nm to 830 nm. Also, the biomedical imaging results indicate that the as-prepared Ag₂S QDs is a nice carrier with low toxicity.



Synthesis and Properties of Bi₂₅FeO₄₀/α-Fe₂O₃ Composite Nanoparticle Photocatalysts^†

CONG Rimin, YU Huaiqing, LUO Yunjun, LI Jiao, WANG Weiwei, LI Qiuhong, SUN Wuzhu, SI Weimeng, ZHANG Hua

2018, 39(4):  629-635.  doi:10.7503/cjcu20170425

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Pure Bi₂₅FeO₄₀ nanoparticles and Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles were synthsized through solvothermal porcess by using polyamidoamine(PAMAM) dendrimer stabilizer with a Bi³⁺/Fe³⁺ molar ratio of 25:1 and 1:1 in the reaction system, respectively. The structure, morphology and properties of the samples were characterized by X-ray diffraction(XRD), high resolution transmission electron microscopy(HRTEM), X-ray photoelectron spectroscopy(XPS), ultraviolet-visible spectroscopy(UV-Vis), Brunauer-Emmett-Teller(BET) surface area analysis and magnetic hysteresis loops measurenent. The results show that these particles are uniform balls with the diameter less than 10 nm. Compared with pure Bi₂₅FeO₄₀ nanoparticles, Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles have smaller band gap, broader visible light absorption range, and significantly greater saturation magnetization and photocatalytic activity. These excellent properties of Bi₂₅FeO₄₀/α-Fe₂O₃ composite nanoparticles come from the superparamagnetic α-Fe₂O₃ component, and the heterogeneous structure of the phase boundary which promotes the efficient separation and migration of photogenerated carriers at the junction interfaces. These nanoparticles could be recycled in external magnetic field, and the catalytic activity decreased slightly after being reused for 3 times.



Analytical Chemistry

Graphene Oxide/Triangular Gold Nanoplates/Nafion Composite Modified Electrode Used for Sensitive Detection of L-Tryptophan^†

LI Yuqing, ZHU Qin, XIAO Zhongliang, LÜ Chaozhi, FENG Zemeng, YIN Yulong, CAO Zhong

2018, 39(4):  636-644.  doi:10.7503/cjcu20170643

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Uniform triangular gold nanoplates(Au TNPs) with good conductivity were synthesized through a seeded growth process, and then modified on surface of glassy carbon electrode(GCE) using graphene oxide(GO) as carrier and Nafion polyanion as protecting agent, finally forming a nanocomposite modified electrode of GO/Au TNPs/Nafion/GCE. The morphologies of the nanocomposites were characterized by means of scanning electron microscopy and atomic force microscopy. The electrochemical behaviors of L-tryptophan(L-Trp) were investigated via cyclic voltammetry(CV) and differential pulse voltammetry(DPV), indicating that GO/Au TNPs/Nafion composite exhibited excellent electrocatalytic oxidation activity to L-Trp. The DPV method was employed for the determination of L-Trp in 0.10 mol/L PBS(pH=3.5), and a good linear relationship between the peak currents and the concentrations of L-Trp was obtained in the range from 4.000×10^-8 to 6.000×10^-5 mol/L, with a detection limit of 1.000×10^-8 mol/L(S/N=3). Furthermore, the modified electrode possessed good reproducibility, stability and selectivity, which can be used for the determination of L-Trp in pork serum samples with recoveries of 93.1%-105.9%, indicating that the proposed method is valuable in practical application on healthy breeding bio-analysis field.



Separation and Structural Sequence Analysis of Sialylated HMOs via Tandem Mass Spectrometry^†

LANG Yinzhi, LIU Shilong, WANG Chen, ZHANG Xiao, LÜ Youjing, CAI Chao, LI Guoyun, YU Guangli

2018, 39(4):  645-652.  doi:10.7503/cjcu20170593

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Sialylated human milk oligosaccharides(SHMOs), important components of human milk oligosaccharides, play a key role in the growth and development of the newborn. Herein, based on the difference of polarity, spatial structure and charge density of sialylated oligosaccharides, a semi-preparative porous graphitized carbon(PGC) chromatography was employed to separate SHMOs in high purity. An off-line electrospray ionization tandem mass spectrometry(ESI-MSⁿ) was performed to identify the sequential structures of eight oligosaccharides including 6'-SL, 3'-SL, LSTb, LSTc, F-LSTc, F-LSTb, DSLNT and FS-LNnH. This study provides a useful reference for the further structure-activity analysis and application development of SHMOs.



Preparation of a Molecularly Imprinted Polymer Nanotubes Membrane and Its Application in the Determination of Catecholamines in Urine Samples^†

QIU Xiuzhen, HUA Yongbiao, GUO Huishi, LU Wenguan

2018, 39(4):  653-659.  doi:10.7503/cjcu20170568

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A molecularly imprinted nanotubes membrane(AAO@MIP) was prepared using dopamine(DA) as template, porous anodic alumina(AAO) as reactor. The morphology of AAO@MIP was characterized by means of scanning electron microscopy(SEM). The specific adsorption performance of AAO@MIP to catecholamines(CLs) was investigated by high performance liquid chromatography(HPLC). Results of adsorption experiments revealed that the AAO@MIP has good extraction capacity and selectivity to dopamine, epinephrine and norepinephrine. A good linearity was achieved for CLs over the range of 0.50-300 μmol/L and the limit of detection(S/N=3) was found to be as low as 15.5, 12.6 and 22.5 ng/L for dopamine, epinephrine and norepinephrine, respectively. The maximum adsorption capacity of AAO@MIP to dopamine can reach 82.1 μmol/g. And the adsorption capacity is only reduced by 3.3% after six times adsorption-desorption. The proposed method was applied to the determination of CLs in human urine samples. The average recoveries ranged from 74.0% to 100.4% with the relative standard deviation(RSD) of 3.6%-6.8%. The developed method is rapid, selective and sensitive, and could be adapted to the analysis of CLs in urine samples.



Determination of the Migration of Methyl Methacrylate in Food Contact Materials by High Field Asymmetric Waveform Ion Mobility Spectrometry Technology^†

LAI Ying, LIN Rui, DONG Qingmu, HUANG Zongping, TU Xingpeng, LIN Weijing, SUN Weijia

2018, 39(4):  660-666.  doi:10.7503/cjcu20170558

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High field asymmetric ion mobility spectrometry(FAIMS) was applied to analyzing the migration of methyl methacrylate in water based food simulants without pretreatment processes, such as extraction or enrichment. By studying the influence of scanning times, sample temperature, sample volume, carrier gas flow-rate and solvent doping on the characteristic signal of methyl methacrylate, the detection limit of methyl methacrylate was determined to be 10 μg/L, and the relationship between the ion current intensity and the concentration of methyl methacrylate was established. The method proposed has the advantages of high sensitivity, easy operation and fast analysis, and can meet the requirements of practical work.



Chemical Transformation of Protopanaxadiol Type Ginsenoside Rb₁, Rb₂ and Rc Analyzed by RRLC-Q-TOF-MS^†

ZHAO Lefeng, JIAO Chuanxin, LI Hui, JIAO Lili, MA Yue, WU Wei, LIU Shuying

2018, 39(4):  667-673.  doi:10.7503/cjcu20170459

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The developed rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry(RRLC-Q-TOF-MS) method was applied for analyzing the chemical transformation of protopanaxadiol(PPD) type ginsenoside Rb₁, Rb₂ and Rc under acidic condition. And Rb₁, Rb₂, Rc and conversion products were analyzed in the ginseng processing. The experimental results demonstrated that chemical transformation mechanisms of protopanaxadiol type ginsenoside in acidic condition included saccharide hydrolysis, Δ20(21)- or Δ20(22)-dehydration, and hydration addition reactions at C24 and C25. The RRLC-Q-TOF-MS/MS analysis included the specific product ions of aglycone PPD(m/z 459), Δ20(21)- or Δ20(22)-dehydration-PPD(m/z 441), and C24, C25 hydrated-PPD(m/z 477). The tandem mass spectrometry(MS/MS) was discussed to provide a basis for structural characterization. The chemical trans-formation pathway for protopanaxadiol type ginsenoside was summarized. The established method was applied for analyzing PPD ginsenosides changes in raw white ginseng and processed red ginseng(100 and 120 ℃).



Organic Chemistry

Anti-tumor and Antimicrobial Activities of β-Carbolines^†

LIU Li, MA Yangyang, WANG Kuan, JIA Yunjing, LI Wan, ZHU Huajie

2018, 39(4):  674-680.  doi:10.7503/cjcu20170636

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A series of β-carbolines possessing different substituents at C1, C3 and N9 positions derived from L-tryptophan was used in anti-tumour and antimicrobial activity study. Compound 3b exhibited anti-tumour activity against tumour cell line A459 with a IC₅₀ value of 3.17 μmol/L in vitro by methyl thiazolyl tetrazolium(MTT) assay while the positive control group(cis-platin, DDP) was 1.45 μmol/L. Other eleven compounds showed relatively weak activities against the five cell-lines. Compound 5h exhibited activitiy against vibrio anguillarum with a MIC value of 0.78 μmol/L while the positive control group(ciprofloxacin) was 1.25 μmol/L. Other fourteen compounds showed relatively weak activities against five spices of bacteria. By the study of structural-activity relationship, optimizing structures is possible and necessary in the future to screen potential compounds for medicinal study.



Effect of Basic Amino Acids on the Biological Activity of Helical Antimicrobial Peptide^†

ZHAO Wencai, HAN Lili, PENG Yingjun, WANG Xiaojing, LIU Shengyu, LI Pengfei, HUANG Yibing, CHEN Yuxin

2018, 39(4):  681-687.  doi:10.7503/cjcu20170596

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In order to investigate the effect of basic amino acids on the biological activity of antimicrobial peptides, an α helical antimicrobial peptides of HPRP-A1 was used to design several peptide derivatives with different K/R ratio by substitution lysine(K) with arginine(R). The relationship between the structure and activity of helical antimicrobial peptides was studied by combining the biophysical properties such as helicity, hydrophobicity and peptide association parameter of antimicrobial peptides. The interaction between helical antimicrobial peptides and different types of cell membranes was further studied by liposome mimic membrane and the cell permeation ability of peptide was examined by 1-N-pbenyl-naphtylamine(NPN) and o-nitrophenyl-β-D-galactopyranoside(ONPG). The results confirmed that the increasing numbers of arginine substitution increased the hydrophobicity and helicity of the antimicrobial peptides, resulting in increasing toxicity of the helical antimicrobial peptides against eukaryotic cell membrane. However, the increasing of arginine was accompanied by decreasing in the ability of peptide association and the permeability of the antimicrobial peptide against the prokaryotic cell membrane, resulting in decreasing of the antibacterial activity of the antimicrobial peptide.



One-pot Fasion Synthesis of Pyrano[2,3-c]pyrazol-6-one Derivatives^†

CUI Siqian, LU Junrui, XIE Zhiqiang, LU Bowei, LIU Jinbiao, LIU Mei, MA Yao, HU Xinlong, LI Jiadong

2018, 39(4):  688-694.  doi:10.7503/cjcu20170594

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Pyrano[2,3-c]pyrazol-6-ones are widely used in the field of medicine and pesticide as a kind of skeletal molecules with high research value and important biological activity. In this work, 15 different substituted pyrano[2,3-c]pyrazol-6-ones(4a-4o) were synthesized rapidly and efficiently under solvent-free conditions by one-pot reaction with two molecules β-keto ester and substituted hydrazine as the starting materials. The yields ranged from 40% to 85%. The products were confirmed by infrared spectroscopy(IR), nuclear magnetic resonance spectroscopy(NMR) and high resolution mass spectrometry data(HRMS). Compared with the traditional synthetic methods, this work overcomes the environmental pollution caused by the use of solvent and the inconvenience of stepwise reaction and has the advantages of solvent-free, mild condition, high yield and easy operation, which also conforms to the green chemistry and economical economy. In addition, the relationship between the reaction rate and yield with the substituent was discussed. The melting reaction process was tracked by ultra-high performance liquid chromatography/high resolution mass spectrometry(UPLC-HRMS) and a new intermediates C was found and identified. Accordingly, a new reaction mechanism for this kind of reaction was proposed, which gave a new understanding of this kind of reaction. In addition, the intermediate C contains a quaternary ring structure but exists in a stable form, which provides a new method for the synthesis of four substituted cyclic butane compounds and ideas for constructing the unstable carbocyclic ring.



Radio-synthesis, Quality Control and Micro-PET Imaging of ⁶⁴Cu-DOTA-TATE^†

LIU Fei, XIE Qing, LIU Teli, XU Xiaoxia, GUO Xiaoyi, LI Nan, ZHU Hua, YANG Zhi

2018, 39(4):  695-700.  doi:10.7503/cjcu20170520

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To investigate the potential of ⁶⁴Cu labeled DOTA-[Tyr3]-octreotate(DOTA-TATE) molecular probe in detecting somatostatin receptor(SSTR) positive tumors. The somatostatin analogue DOTA-TATE was radiolabeled with ⁶⁴Cu to prepare ⁶⁴Cu-DOTA-TATE. The stability of the probe was measured in 5%(volume ratio) HSA and 0.9%(volume ratio) saline solutions. After purification, 18.5 MBq of ⁶⁴Cu-DOTA-TATE was injected intravenously to nude mice bearing human pancreatic cancer via tail vein, micro-PET images were taken after radiotracer injection 1 and 10 h. After purification with 80%(volume ratio) ethanol, the radiochemical purity of ⁶⁴Cu-DOTA-TATE was over 99%, and could keep stable for 40 h in 5% HSA and 0.9% saline solutions. As shown in micro-PET imaging, tumor uptake was visualized after post injection 1 h, with the uptake increased after 10 h. ⁶⁴Cu-DOTA-TATE may be useful for imaging somatostatin receptor-positive tumors.

Virtual Screening and Activity Verification of Novel Inhibitors of ApIV 3C Protease^†

SHI Yanli, LIU Yubo, WU Sijin, LIU Yajun, ZHANG Jianing, LI Wenli

2018, 39(4):  701-707.  doi:10.7503/cjcu20170392

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Antheraea pernyi iflavirus(ApIV) is an important cause of antheraea pernyi vomiting disease(AVD) which is seriously harming the production of Antheraea pernyi(A. pernyi) industry in China. ApIV is a single-stranded, positive-sense RNA virus, belong to the picornavirida family. Due to the significant role of 3C protease in virus replication, it is considered to be an attractive drug target for developing antiviral therapeutic agents. Although great efforts have been made to develop 3C protease inhibitors, no effective anti-viral therapy for the prevention or treatment of diseases caused by ApIV infection is available. In this study, an effective inhibitor of ApIV 3C protease, 3',4',5,7-tetrahydroxyisoflavone(Orobol), was identified through virtual screening using molecular docking against natural product library. And the binding mode of Orobol with ApIV 3C protease was stable through molecular docking and molecular dynamics simulation(MD). The biological data displayed that the inhibition ratio of virus replication was stronger with the increase of the concentration of Orobol. And when the concentration of Orobol was 10 μg/mL, the inhibition ratio reached 80.5%. In vivo assay also demonstrated that Orobol could inhibit viral replication in spodoptera frugiperda cell(Sf9) cells. Those results proved that Orobol was a novel inhibitor for the disease of antheraea pernyi caused by ApIV infections.



Physical Chemistry

Fabrication of Monolayer Crystalline Films on Optical Fiber End by Micro-flow Injection Method^†

DENG Caisong, PAN Tingting, DU Lan, WANG Ming, NI Haibin, NI Xiaoqi

2018, 39(4):  708-713.  doi:10.7503/cjcu20170690

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A new method of preparing monolayer crystalline film on optical fiber end is proposed. Micro-flow injection method enables the formation of a well-organized monolayer of hexagonally arranged colloidal nanosphere arrays directly on the water surface, which is then transferred onto the preset fiber substrates, the area is up to square centimeters. The nanostructural morphology and optical properties of the samples were examined and analyzed by SEM and spectrum analyzer. It has been found that the colloidal crystal on the end face of optical fiber is hexagonally arranged. Transmission spectrum shows that the existence of photonic band gap, and the stopgap is located at 700 and 850 nm, which is coincide with simulation results of FDTD Solutions software. Combined with sputtering deposition, the silver spherical shell array structure was obtained, and its localized surface plasmon resonance(LSPR) was tested. Finally, the effect of solution concentration, meniscus formation and injection speed on the quality of micelle assembled colloidal film was discussed.



Molecular Dynamics Simulation on the Structure of Cellulose Inclusion Complexes and Interactions Between Cellulose Chains and Solvent Molecules in Alkali/urea Aqueous Solution^†

LIU Gang, ZHANG Heng, SUN Heng, ZHU Hongxia, ZHANG Yuhan, ZHU Qingzeng, YUAN Shiling

2018, 39(4):  714-720.  doi:10.7503/cjcu20170683

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The detail structure of cellulose inclusion complexes(ICs) in alkali/urea aqueous solution was investigated using molecular dynamics simulation. The spatial structure of cellulose ICs, the hydrogen-bonding network, the interactions between cellulose chains and solvent molecules and the effect of alkali metal ions on the formation of ICs were studied. The simulation results showed that the sodium ions and hydroxide ions mostly located and formed stable absorption conformation around hydroxyl and hydroxymethyl groups of cellulose. Urea molecules preferred to occupy the faces of the hydrophobic pyranose rings and form hydrogen bonds with hydroxyl groups and the pyranose ring oxygen. The interactions between cellulose chains and solvent molecules were also simulated. Nearby the hydroxyl groups, the non-bonding interactions between solvent molecules and hydroxylic oxygen atoms of cellulose were in the order of Na⁺>NH₂CONH₂>OH^->H₂O. On the faces of the pyranose rings of cellulose, urea molecules exhibited the strongest interaction with hydroxylic oxygen atoms. The effects of alkali metal ions in KOH/urea and NaOH/urea aqueous solutions on the stability of ICs were also discussed. Compared with K⁺, Na⁺ could form a more stable configuration of cellulose ICs.



Theoretical Study on the Formation Mechanism of Catalytic Active Components in Suzuki-Miyaura Cross-Coupling Reaction Catalyzed by Transition Metal Cobalt Complex^†

ZHANG Wei, ZHANG Yiwei, LI Hui, LEI Ming

2018, 39(4):  721-728.  doi:10.7503/cjcu20170652

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The reaction mechanism of Co(Ⅰ) complex (^iPrPNP)CoOR formation in Suzuki-Miyaura cross-coupling reaction catalyzed by cobalt complex was studied via density functional theory(DFT) calculation. The calculated results indicate that a phosphine ligand in the diisopropyl-substituted bis(phosphino)pyridine pincer ligand(^iPrPNP) is dissociated from the Co metal center to produce INT1', the dissociative path at triplet state is the most favorable reaction path to form (^iPrPNP)CoOR than the non-dissociative path. The concerted mechanism of Co(Ⅰ) complex (^iPrPNP)CoOR produced by INT1' is more favorable than the stepwise mechanism in the dissociative path. The effect of substituent groups of substrate HOR was studied, which in agreement with experimental observations. The reaction mechanism could provide a theoretical insight into the whole Suzuki-Miyaura cross-coupling reaction mechanism.



Preparation and Performance of Pt/IZM-2 Catalyst on the Hydroisomerization of n-Dodecane^†

LI Chuansong, DU Yanyan, XUE Xuzhi, XIANG Xianzheng, LI Jiusheng, REN Tianhui

2018, 39(4):  729-734.  doi:10.7503/cjcu20170612

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IZM-2 added CTAC(cetyltrimethylammonium chloride) was synthesized by hydrothermal method. The bifunctional catalysts 0.5%Pt/IZM-2 were prepared via the incipient wetness impregnation technique, and their catalytic performance of the hydroisomerization of n-dodecane was investigated on the fixed-bed continuous-flow reactor. SEM and BET analysis prove the agglomeration weakening of the catalyst. NH₃-TPD and H₂-TPR results show the weaker reduction ability and fewer medium/strong acid sits of Pt/IZM-2-CTAC. The results showed that the aggregation effect of the IZM-2 particles is obviously inhibited after the addition of cation surfactants, and the mesoporous pore volume and specific surface area are increased, which provides more space for the diffusion of the reaction intermediates and shortens the residence time of the isomers in the pores. Thereby it surpresses the occurrence of the cracking reaction and increases the hydroisomerization selectivity as well as the yield of isoparaffins.

Depolymerization of the Alkali Lignin for Aromatic Compounds over Ni/SiO₂-Al₂O₃ Solid Acid Catalysts^†

ZHOU Lie, WU Qingyun, XU Ying, WANG Chenguang, MA Longlong, LI Wenzhi, CHEN Peili

2018, 39(4):  735-742.  doi:10.7503/cjcu20170591

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Optional discarded and unreasonable utilization of industrial alkali lignin leaded to water and air pollution. However, alkali lignin could be utilized as fine chemical resource for its specific phenyl propane structure. In this paper, we investigated efficient depolymerization methods on alkali lignin aiming for aromatic products over acidic SiO₂-Al₂O₃ and Ni/SiO₂-Al₂O₃ by one-step. The effects of Ni metal loading contents, reaction temperature and reaction time in this process were also discussed. Analysis of lignin depolymerized products were carried with gas chromatography(GC), gas chromatography-mass spectrometry(GC-MS), Fourier transform-infrared spectroscopy(FTIR). The results showed that Ni/SiO₂-Al₂O₃ can promote the conversion of the alkali lignin. Yield(mass fraction) of aromatic products increased and then decreased along with the rising of reaction temperature, which the yield of arenes was 9.05% and the yield of aromatic products was 22.53% over 15%Ni/SiO₂-Al₂O₃ catalyst at 300 ℃ after depolymerization. Reaction time also showed significantly influence on depolymerized products, with the reaction times increasing. The arenes yield was increased and then stabilized, aromatic products yield reached 26.54% after reacted 12 h.



Adsorption of Iodoperfluoroalkanes on Tetrabutyl Ammonium Halide by Halogen Bond^†

YAN Xiaoqing, LIU Qiushuang, LIU Yunfeng, NIU Qiao

2018, 39(4):  743-748.  doi:10.7503/cjcu20170495

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The adsorption of 1,2-diiodotetrafluoroethane(C₂F₄I₂) on tetrabutyl ammonium iodide(Bu₄N⁺I^-) was analyzed by IR, UV and ¹⁹F NMR spectroscopies. The according spectrum changes of IR, UV and ¹⁹F NMR indicated that halogen bond complexes were formed in solution, which demonstrated that the adsorption was due to the C-I…I^- halogen bonding interactions. The adsorptivities of five quaternary ammonium salts were compared and the experiment results showed that adsorptivity was Bu₄N⁺Cl^->Bu₄N⁺Br^->Bu₄N⁺I^-. Hexadecyl trimethyl ammonium chloride and hexadecyl trimethyl ammonium bromide, which have long alkyl chain, had absolutely no adsorption to C₂F₄I₂. It is probably because that the long alkyl chains prevented halide anion from closing to C₂F₄I₂. The adsorption of four iodoperfluoroalkanes(C₄F₈I₂, C₄F₉I, C₆F₁₂I₂, C₆F₁₃I) by Bu₄N⁺Cl^- salt were investigated. The results showed that although halogen bonds in the monoiodoperfluoroalkanes(monoiodo-PFAs) complexes were stronger than those in the diiodoperfluoroalkanes(diiodo-PFAs) complexes as estimated by Raman spectra in solution, the adsorptivities of Bu₄N⁺Cl^- for the diiodo-PFAs were stronger than those for the monoiodo-PFAs at the solid/liquid interface because the odds of forming halogen bond of diiodo-PFAs is double that of monoiodo-PFAs. Besides, it was found that the formation of halogen bonds could enhance the Raman signals of iodoperfluoroalkanes.



Theoretical Studies of Structural Design and Stability of Double-layered Sandwich-like Tetrapyrrolic Uranium Complexes^†

TIAN Linfei, ZHANG Chunhua, QU Ning, BI Yanting, ZHANG Hongxing, PAN Qingjiang

2018, 39(4):  749-757.  doi:10.7503/cjcu20170463

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To explore the interaction between tetrapyrrolic ligand and low-valent uranium ion, double-layered Sandwich-like complexes PzU^mPzU^mPz(labeled as $U^{m}_{2}$ Pz₃; m=Ⅲ and Ⅳ, Pz=porphyrazine) were designed according to the single-layered PcU^ⅥPc(Pc=phthalocyanine) that was experimentally synthesized. Relativistic density functional theory(RDFT) was used to examine structures, stability and chemical bonding. It is shown that complexes $U^{m}_{2}$Pz₃ have the quintet ground state. Steric configurations are found to have a little effect on isomeric stability, while electron-spin states play more important role. Topological analyses of electron density suggest weakly polarized covalent character for U-N bonds. Tetravalent diuranium complex possesses four U(5f)-character high-lying occupied orbitals, in accordance with U^Ⅵ 5f-electron number counting. Differently, some electron transfer from uranium to ligand(Pz) is unraveled for the trivalent complex, leading to more ligand contribution to frontier molecular orbitals.

Raman Spectroscopic Investigation on the Effect of Hydrogen Bond on Molecular Structure in Ternary Aqueous Solution^†

OUYANG Shunli, ZHANG Mingzhe, ZHANG Yongzhao, HU Qingcheng, WEI Haiyan, WU Nannan, HUANG Baokun

2018, 39(4):  758-763.  doi:10.7503/cjcu20170445

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The effect of hydrogen bond on the molecular structure in water-acetonitrile-dimethyl sulfoxide ternary system was investigated by Raman spectroscopy. The molecular interactions in water-acetonitrile-dimethyl sulfoxide ternary system, with different molar ratios were investigated by Raman spectroscopy. The results show that the electron cloud of the C≡≡N bond get closer to carbon atom, while the electron cloud of the S＝O bond get closer to sulfur atom in ternary mixture. In addition, there exists an obviously competitive relationship between acetonitrile and DMSO when they form hydrogen bond with water in this ternary system, and there exists the situation in which acetonitrile molecule and DMSO molecule share one water molecule to form the compounds. With increasing the proportion of water, this situation gradually disappears. The research provides experimental basis for enriching the hydrogen bonding theory in ternary aqueous solution system.



Ion Transfer of Leucovorin Ion Across the Membrane-modified Liquid/Liquid Interface^†

ZHANG Yehua, JIANG Tao, LIU Shufeng, YU Yaqian, CHEN Yong

2018, 39(4):  764-770.  doi:10.7503/cjcu20170413

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The ion transfer of leucovorin ion across the water/1,6-dichlorohexane(W/DCH) interface modified by hybrid mesoporous silica membrane(HMSM) was studied by employing cyclic voltammetry(CV), differential pulse voltammetry(DPV) and chronocoulometry. It was found that the electrochemical behaviors of ion transfer of leucovorin ion across such a membrane-modified W/DCH interface are closely related with the ionic surfactant cetyltrimethylammonium bromide(CTAB), which was self-assembled within the silica nanochannels of the HMSM. According the linear relationship between the peak current of CV corresponding to the ion transfer of leucovorin ion from water to DCH and the square root of scan rate, as well as the equation of Randles-Sevčik, the diffusion coefficient of leucovorin ion in water was calculated to be about 2.036×10^-8 cm²/s. In addition, the standard reaction rate constant of the ion transfer of leucovorin ion at such a membrane-modified W/DCH interface was estimated to be about 2.72×10^-3 cm/s via chronocoulometry. This work is expected to help understanding the transport processes of leucovorin across biomembrane in bioscience and provide an elctrochemical method to detect calcium leucovorin.



Preparation and Photoelectrocatalytic Performance of Fe₂O₃/ZnO Composite Electrode Loading on Conductive Glass^†

HAN Zhiying, LI Youji, LIN Xiao, WANG Ziyu, LI Ziqin, WANG Hao

2018, 39(4):  771-778.  doi:10.7503/cjcu20170388

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Using polyvinylpyrrolidone(PVP) and ethanol as fiber skeleton and solvent, respectively, Fe₂O₃/ZnO precursor fibers were prepared by sol-gel method combined with electrospinning technique with zinc acetate [Zn(CH₃COO)₂·2H₂O] and three iron acetylacetonate(C₁₅H₂₁O₆Fe) as raw materials. Fe₂O₃/ZnO/FTO composite photoelectrodes with different Fe/Zn molar ratios were obtained by calcination. The morphologies and chemical components were characterized by thermogravimetry-differential thermal analysis(TG-DTA), X-ray diffraction(XRD), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), and so on. The photoelectrocatalytic performance of the obtained sample was tested by the degradation of methylene blue(MB) solution. The results indicate that the p-n heterojunctions between ZnO and Fe₂O₃ are beneficial for separation of photogenerated electrons and holes, resulting in Fe₂O₃/ZnO/FTO with high catalytic activity in comparsion with ZnO/FTO and Fe₂O₃/FTO. The composite photoelectrodes with different Fe/Zn molar ratios exhibit different photoelectrocatalytic activity. When n(Fe)/n(Zn) is 1:1, the catalytic activity of Fe₂O₃/ZnO/FTO is the optimal, the degradation rate of MB is 97% after 140 min.



Paired Electrosynthesis Using Furfural as Raw Material^†

LIU Honghong, LIU Lichao, ZHANG Wenli, HE Yapeng, HUANG Weimin, LIN Haibo

2018, 39(4):  779-784.  doi:10.7503/cjcu20170368

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In order to choose the best electrode for the electrochemical oxidation of furfural to furfuryl acid, the oxygen evolution and the electrocatalysis for the oxidation of furfural of Ti/Ru-Ti-Sn, Ni, Ti/PbO₂, Pt and Ti/BDD were studied. The effects of pH of the solution, current density, concentration of furfural, temperature and electrolysis time on the electrochemical reduction of furfural to furfuryl alcohol and the electrochemical oxidation of furfural to furoic acid were investigated using Ni anode. The results showed that the best current efficiency was 130% at pH=11, cathodic current density 2 mA/cm², anodic current density 1 mA/cm², concentration of furfural 0.1 mol/L, temperature 25 ℃, cathodic electrolysis time 4 h and anodic electrolysis time 6 h.



Polymer Chemistry

High Flux Polybenzimidazole Solvent Resistant Nanofiltration Membranes: Morphology Control and Performance^†

ZHAO Caixiu, YANG Yi, LIU Yiting, JIANG Ying, YUAN Fang, WANG Rui, CHEN Dongju

2018, 39(4):  785-792.  doi:10.7503/cjcu20170618

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A kind of heterocyclic polymerpolybenzimidazole(PBI) membranes are very promising for solvent resistant nanofiltration due to their excellent mechanical stability, thermal stability and chemical stability. Even though they showed high selectivity, however, the permeance is relatively low. In this study, we aim to enhance the permeance of PBI membranes while keep their selectivity. PBI membrane with different microstructures were prepared by introducing polyvinylpyrrolidone(PVP) in cast solution. The results showed that with increasing content of PVP, the flux of membrane increases, while, the rejection on dyes keeps constant. When the mass ratio of PVP is 15%, the PBI showed retention of 99.18% on methylene blue, showing very good selectivity.



Preparation and Characterization of Star-shaped β-Cyclodextrin Based Polymer^†

YANG Qinghua, WANG Longgang, LIU Jie, LU Yong, CHEN Tianyun

2018, 39(4):  793-799.  doi:10.7503/cjcu20170561

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β-Cyclodextrin with terminal amino moiety(6-en-β-CD) was prepared by β-cyclodextrin(β-CD) as starting material through sulfonation and ethylenediamine substitution. Then, the target polymer[6-poly(glumatic acid-lysine)-β-CD] was obtained by ring opening polymerization(ROP) of glumatic acid and lysine N-carboxyl anhydride(NCA) and deprotection of benzoxycarbonyl(Cbz), with β-CD and polypeptides as its core and branched arms, respectively. The characters of the star-shaped polymer and its corresponding intermediates were determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF-MS), nuclear magnetic resonance(NMR) and Fourier transform infrared spectroscopy(FTIR), respectively. Moreover, the secondary structure and the cytotoxicity in vitro were also detected by circular dichroism(CD) and methylthiazolyldiphenyl-tetrazolium bromide(MTT) assay, respectively. The results showed that successful synthesis of the target polymer and its intermediates was achieved, and the molecular weight(M_w) of the target polymer, polydispersity index(PDI) and average degree of polymerization(DP) were 4626, 1.10 and 27.1, respectively. Furthermore, the secondary structure of the target polymer in water was random coil. The cell viability of human umbilical vein endothelial cells(HUVECs) could reach over 94% when the polymer concentration was up to 5 mg/mL, exhibiting no cell toxicity in vitro. In conclusion, our studies demonstrated that the polymer had potential applications in pharmacy industry.



Visible Light Induced Rapid Reversible Addition-fragmentation Chain Transfer Polymerization(RAFT )of Styrene at Room Temperature^†

LUO Juxiang, CHENG Deshu, LI Mingchun, XIN Meihua

2018, 39(4):  800-806.  doi:10.7503/cjcu20170546

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The implementation of photoinitiators and photocatalysts-free visible light induced reversible addition-fragmentation chain transfer(RAFT) polymerization processes at room temperature has the potential to afford greener methodology to the preparation of polymeric materials. However, these previous works pointed out that photoinduced RAFT polymerization of styrene(St) at room temperature was very slowly even with exogenous photoinitiators or photocatalysts. In this work, we aim to overcome these drawbacks via the implementation of commercial blue light-emitting diodes(LEDs) as visible light source in the RAFT polymerization of St at room temperature with S-1-dodecyl-S'-(α,α'-dimethyl-α″-aceticacid)trithiocarbonate(DDMAT) as RAFT agent, without exogenous photoinitiators or photocatalysts. The polymerization rate was comparatively rapid and the results of polymerization kinetics of St show that the polymerization exhibits good living characteristics. Importantly, the polymerization could be instantly switch “On” or “Off ” in response to visible light, and the switching cycles of light had no effect on the living character of polymerization. Finally, the photo-fragmentation and photo-degradation of DDMAT were investigated by in situ ¹H NMR(nuclear magnetic resonance) spectroscopy. The detailed study provides a deeper understanding of the chemical processes of the polymerization method.



Effects of Electrospun Fiber-Stiffness on Adhesion and Migration of iPS-MSCs^†

YU Zhepao, YUAN Huihua, YI Bingcheng, WANG Xianliu, ZHANG Zhaowenbin, ZHANG Yanzhong

2018, 39(4):  807-816.  doi:10.7503/cjcu20170542

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The stiffness of as-electrospun poly-L-lactic acid(PLLA) fibers was altered by annealing treatment, and then influence of fiber stiffness on the morphology, proliferation and migration of induced pluripotent stem cell-derived mesenchymal stem cells(iPS-MSCs) were evaluated. The results showed that annealing treatment had negligible influence on the diameter of PLLA fibers[before: (1.26±0.25) μm and after: (1.24±0.26) μm]. However, fiber crystallinity and mechanical properties were enhanced, which resulted in 1.73 times stiffer than that of fibers before annealing treatment. The cell spreading area and proliferation of iPS-MSCs cultured on the treated PLLA scaffold after 1 and 7 d of incubation were 1.78 and 1.18 times higher, respectively, than that of untreated scaffold. The increase of fiber stiffness can affect the migration of iPS-MSCs and promote up-regulated expression of the migration-related genes Integrinβ1, RhoA and Rock1. Collectively, this study demonstrated that increasing fiber stiffness by annealing may be used as an important modality to regulate cell biological functions of the cells in engineering tissues.



Numerical Simulation of Swelling and Drug Release Processes for Weak Polyelectrolyte Hydrogels^†

YE Hui, LIU Yabo, JIA Yuxi

2018, 39(4):  817-824.  doi:10.7503/cjcu20170541

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Based on the three-phase model, a mathematical model of swelling and drug release for weak polyelectrolyte hydrogels was established by combination of Langmuir isothermal adsorption equation and drug release equation; the finite element method was adopted to investigate the influence of the material parameters on swelling and drug release in the case of drugs were distributed within the weak polyelectrolyte hydrogels homogeneously; the mechanism of drugs released from weak polyelectrolyte hydrogels in different moments was analyzed as well; then the impacts of drug distribution conditions within the hydrogels which consist of homogeneous distribution and inhomogeneous distribution on swelling and drug release were compared comprehensively, and it has been found that drug release process is consistent with zero order release kinetics when drugs presented the sine distribution in the hydrogels; finally, the simulated results were comparatively compared with Beebe’s experimental results to validate the accuracy of this simulation.



Preparation of AOPAN@PAN Coaxial Nanofiber Membrane and It’s Adsorption Property^†

REN Jing, WANG Shugang, LI Yanchun, YANG Qingbiao, SONG Yan, LI Yaoxian

2018, 39(4):  825-831.  doi:10.7503/cjcu20170482

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Amidoxylated polyacrylonitrile(AOPAN) solution was prepared by the reaction of hydroxylamine hydrochloride and polyacrylonitrile(PAN). At the same time, the coaxial nanofibers(AOPAN@PAN) with AOPAN as shell and PAN as core was prepared by coaxial electrospinning technology. And the morphology, composition and mechanical properties of nanofibers were characterized by means of transmission electron microscopy(TEM), scanning electron microscopy(SEM) and infrared(FTIR). The results showed that the strength of AOPAN@PAN coaxial nanofibers increased with the increase of PAN dosage. The tensile strength and elongation at break of nanofibers was 3.677 MPa and 18.03% when the mass ratio of core to shell was 1∶3, and the maximum adsorption capacities of Cu^{2 +}, Pb^{2 +}, Cr$O^{2-}_{4}$ and methyl orange(MO) was 135.1, 151.2, 120.48 and 43.45 mg/g, respectively. At the same time, the concentrations of Cu²⁺, Pb^{2 +}, Cr$O^{2-}_{4}$ and MO are reduced to 0.17, 0.03, 0.06 and 0.91 mg/L after treatment with this nanofiber.



Enhancement Mechanisms of Mechanical and Self-Healing Properties of Thermoplastic Polyurethane Composites Induced by Different G-CNT Hybridization Systems^†

GAO Feilong, LI Yongcun, LUAN Yunbo, XUE Zhicheng, GUO Zhangxin, ZHANG Qi, WU Guiying

2018, 39(4):  832-840.  doi:10.7503/cjcu20170384

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Three different hybridization degrees of the three dimensional structure of graphene-carbon nanotube(G-CNT) were prepared by the different experimental schemes. The research on the mechanical property of the thermoplastic polyurethane(TPU) composites reinforced by this three-dimensional hybrid structure of the G-CNT, and the behavior of self-healing of the damaged TPU composites was carried out. The results show that the three dimensional hybrid structure of G-CNT can effectively promote the load transfer between the reinforcing phase and the TPU matrix, and can improve the mechanical properties of the TPU composites. It also shows that the higher the hybridization degree of G-CNT, the more the enhancement effect will be. When the G-CNT was prepared by the pre-hybridization method, it achieved the highest hybridization degree. And the mechanical properties of the corresponding composite G-CNT/TPU achieved the highest value that equals to 61.95 MPa. It is about 37.6% higher than the pure TPU and 27.10% higher than the G/TPU composite. Meanwhile, it shows that these composites can realize the self-healing of the crack induced by the microwave electromagnetic fields. The tensile strength of these healed samples were even higher than that of their original samples. However, their healing efficiency does not increase as the hybridization degree of G-CNT increased. For example, as for the composite of G-CNT/TPU that prepared by the ultrasonic hybrid method, the hybridization degree of G-CNT is less than that prepared by the pre-hybrid method, but its healing efficiency achieved the highest that equals to 138%. This self-healing characteristic has important relationship with the spatial structure of the 3D G-CNT and the coupling mechanisms between microwave and the heterogeneous interface within G-CNT.