Table of Content

10 January 2014, Volume 35 Issue 1

Previous Issue    Next Issue

Content

Cover and Content of Chemical Journal of Chinese Universities Vol.35 No.1(2014)

2014, 35(1):  0-0. 

Asbtract ( )   PDF (13521KB) ( )  

Related Articles | Metrics

Review

Recent Progress of Microfluidic Techniques for Protein Crystallization and Screening^†

ZHU Lina, ZHU Ying, FANG Qun

2014, 35(1):  1-11.  doi:10.7503/cjcu20130691

Asbtract ( )   HTML ( )   PDF (3746KB) ( )  

Figures and Tables | References | Related Articles | Metrics

With the advantages of high throughput, low consumption and large-scale integration, microfluidics has proven to be a promising technique for protein crystallization and screening. This article reviews the recent progress of various microfluidic techniques successfully applied in protein crystallization, including PDMS-based valve and pump, droplet, SlipChip and DropLab. In addition, due to the high importance and great challenges of membrane proteins in structural biology, we further introduce the microfluidic techniques for crystallization of membrane proteins.



Articles: Inorganic Chemistry

Synthesis, Crystal Structure and Magnetic Properties of Tetranuclear Mn^Ⅱ₂Mn^Ⅲ₂ Complexes Based on 2-(Hydroxymethyl)-N-methylimidazole^†

SHI Wenbo, KOU Huizhong

2014, 35(1):  12-18.  doi:10.7503/cjcu20130671

Asbtract ( )   HTML ( )   PDF (1907KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Three new 2-(hydroxymethyl)-N-methylimidazole-bridged tetranuclear Mn^Ⅱ₂Mn^Ⅲ₂ complexes [Mn₄(hmmi)₆(DMF)₂(N₃)₂](ClO₄)₂(1), [Mn₄(hmmi)₆(H₂O)₂(N₃)₂](ClO₄)₂(2) and [Mn₄(hmmi)₆Cl₄]·6CH₃CN(3·6CH₃CN)[Hhmmi=2-(hydroxymethyl)-N-methylimidazole] were synthesized, and their crystal structures and magnetic properties were studied. In the mixed-valent [Mn₄]²⁺ cores for complexes 1—3, Mn^Ⅱ are located at the sides, and Mn^Ⅲ in the middle. Best fit to the experimental data for complexes 1—3 suggests the presence of ferromagnetic coupling for Mn^Ⅲ-Mn^Ⅲ, while weak ferromagnetic or antiferromagnetic coupling for Mn^Ⅲ-Mn^Ⅱ or intermolecular interaction.



Controllable Synthesis and Photocatalytic Activity of TiO₂/LaFeO₃ Micro-nanofibers^†

LIU Yang, JI Hongwei, ZHOU Defeng, ZHU Xiaofei, LI Zhaohui

2014, 35(1):  19-25.  doi:10.7503/cjcu20130886

Asbtract ( )   HTML ( )   PDF (2900KB) ( )  

Figures and Tables | References | Related Articles | Metrics

TiO₂/LaFeO₃ heterostructures were fabricated by electrospinning technique and hydrothermal synthesis method. The physicochemical properties of the catalysts were characterized by scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR) and ultraviolet-visible diffuse reflectance spectra(UV-Vis). The photocatalytic activity of TiO₂/LaFeO₃ micro-nanofibers toward the decomposition of methylene blue(MB) was investigated. The results indicate that defect sites of incompletely carbonized TiO₂ fibers are favorable for the growth of LaFeO₃ nanoparticles. The band gap of TiO₂/LaFeO₃ heterostructures is lower than TiO₂ improving the photocatalytic activity. After 140 min TiO₂/LaFeO₃ heterostructures exhibited 65.34% for MB under UV light, and the photocatalytic mechanism of TiO₂/LaFeO₃ heterostructures were analyzed and discussed.



Synthesis of Length Controllable Ordered Mesoporous Rodslike SBA-15 by Co-surfactant Method^†

WANG Min, LI Dong, CAI Wenjing, JIANG Nanzhe

2014, 35(1):  26-29.  doi:10.7503/cjcu20130814

Asbtract ( )   HTML ( )   PDF (3476KB) ( )  

Figures and Tables | References | Related Articles | Metrics

SBA-15 rods with different lengths(from hexagonal paticials to short rods, and to longer rods) were synthesized via triblock copolymer P123 as a structure-directing agent and chitosan as a co-surfactant. The results show that chitosan is indispensable for tuning the length of SBA-15 rods. Addition of chitosan could improve the periodicity of the SBA-15 and the specific surface area and total proe volume are increased to 1157 cm²/g and 1.53 cm³/g, respectively.



Analytical Chemistry

Detection of Inhibitory Effects of Suramin and Cisplatin on Hepatocellular Carcinoma Cells Using Surface Plasmon Resonance Imaging^†

XIE Fei, ZHANG Ying, JIN Wei, PAN Tingting, ZHOU Chao, REN Hao, JIN Qinhan, MU Ying

2014, 35(1):  30-36.  doi:10.7503/cjcu20130854

Asbtract ( )   HTML ( )   PDF (2789KB) ( )  

Figures and Tables | References | Related Articles | Metrics

A rapid, label-free and novel evaluation of anti-cancer drug efficacy was proposed via surface plasmon resonance imaging(SPRi). A microfluidic chip with micro-posts was designed and fabricated in polydimethylsiloxane(PDMS) to work as a continuous flow cell. Specific entrapment and detection of tumor cells were accomplished by a homemade SPRi system with the microfluidic chip. On this basis, the inhibitory effects of suramin and cisplatin on the proliferation of HepG2 cells was investigated. Meanwhile, we used auxiliary cell counting kit-8(CCK-8) assay to examine cell viability after drug incubation. The results of the SPRi method showed that both suramin and cisplatin could inhibit the proliferation of HepG2 cells in a dose-dependent and time-dependent manner.



Fragmentation Reactions of Complexes of Alkali Metal Ions with Pentaserine, Pentaleucine and Pentalysine in Gas Phase^†

WEI Wanghui, WANG Qing, CHU Yanqiu, WANG Rizhi, DING Chuanfan

2014, 35(1):  37-47.  doi:10.7503/cjcu20130721

Asbtract ( )   HTML ( )   PDF (1583KB) ( )  

Figures and Tables | References | Related Articles | Metrics

For exploring the effects of alkali metal ions on the dissociations of peptides with different side chains in the gas phase, the complexes of Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺ with pentapeptides, Ser-Ser-Ser-Ser-Ser(S5), Leu-Leu-Leu-Leu-Leu(L5) and Lys-Lys-Lys-Lys-Lys(K5), were chosen to investigate the fragmentation reaction pathways by mass spectrometry. The experimental results indicated that alkali metal ions and S5, L5, K5 can form 1∶1 and 2∶1 non-covalent complexes in the gas phase, and the binding strength between alkali metal ions and pentapeptides descend with the increasing of the radii of alkali metal ions. Quantitative analyses of mass spectra demonstrated that the binding constants for the complexes of K⁺ with S5, L5 and K5 are 8.94×10⁴, 2.83×10⁴ and 2.50×10³ L/mol, respectively, revealing that the binding strength of complexes decrease in order of S5, L5 and K5. The analyses of the fragment ions arising from the complexes of alkali metal ions with pentapeptides showed that the dissociations mainly occur in the backbones of the peptides. Among three pentapeptides, the complexes of pentaserines are the easiest to fragment, pentaleucines take second place, while pentalysines are the hardest. The dissociations also occur in the side chains, and there are significant differences among the three complexes. Moreover, the relationships among various fragment ions arising from the complex of Na⁺ with L5 were tested. Based on the theoretical model of Dunbar, it was proposed that in the fragmentation process, the alkali metal ion may shift to the N- or C-terminal of the pentapeptide. In 2∶1 complex, the first alkali metal ion may conjugate to the carbonyl groups of four amides, while the second one may conjugate to the oxygen atoms of carboxyl group of the pentapeptide.



Organic Chemistry

Synthesis and Photoelectricity of Novel Zn Metal Complex Based on 8-Hydroxyquinoline with Thiophene Group^†

TANG Yinmin, HUO Yanping, HU Sheng, ZHANG Kun, ZHAO Fenghua, OUYANG Xinhua

2014, 35(1):  48-53.  doi:10.7503/cjcu20130487

Asbtract ( )   HTML ( )   PDF (2678KB) ( )  

Figures and Tables | References | Related Articles | Metrics

8-Hydroxyquinoline has long been employed as analytical and separating agents due to its universal chelating ability offered by the heterocyclic N and phenolate O atoms and fiuorescent property possessed by the conjugate system. In order to increase its fluorescence capability and conjugate system, 3-thiophene has been added. A novel 8-hydroxyquinoline derivative ligand containing thiophene group (E)-2-[2-(3-thiophenyl)ethenyl]-8-hydroxyquinoline(4) and its corresponding zinc complex(5) were synthesized and identified via ¹H NMR, FTIR, UV-Vis, X-ray structural analysis and elemental analyses. The crystal structures of intermediate (E)-2-[2-(3-thiophenyl)ethenyl]-8-acetoxyquinoline(3) and ligand 4 were characterized by single-crystal X-ray diffraction. X-Ray structural analysis showed that there was no obvious hydrogen-bonding interaction between the molecules of compound 3. The crystal reticular structure of compound 4 was constructed as a result of intermolecular O-H…S hydrogen bonds. The aggregation behaviors of zinc salts and compound 4 in solutions were investigated with a variety of techniques, including ¹H NMR, UV-Vis and fluorescence.The fluorescence lifetime of complex 5 was determined in the solid state and its τ value is 18.8 ms. Organic light-emitting diodes built using complex 5 emitted yellow light, in which the 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene(TPBi) acts as the electronic transmission layer, while N,N'-bis-(1-naphthalenyl)-N,N'-bis-phenyl-(1,1'-biphenyl)-4,4'-diamine(NPB) acts as hole transport material.



Phenoxyacetylcobalt Tetracarbonyl as Catalyst for Copolymerization of Imines and CO to Produce Polypeptides^†

ZHANG Yongpo, SUN Huailin

2014, 35(1):  54-57.  doi:10.7503/cjcu20130435

Asbtract ( )   HTML ( )   PDF (988KB) ( )  

Figures and Tables | References | Related Articles | Metrics

A new phenoxyacetylcobalt tetracarbonyl catalyst was synthesis and used to catalyze alternating copolymerization of imines and CO. ¹H NMR study indicated that this catalyst existed in the form of an equilebium between the aklycobalt and acylcobalt complexes under 1×10⁵ Pa of CO atmosphere. The results obtained using the catalyst in imines and CO copolymerization demonstrates that this catalyst had good performance, producing polypeptides of high molecular weights, with phenoxyacetyl groups at the starting ends of the polymer chains, and of narrow molecular weight distributions. The structures of polypeptide obtained were characterized by ¹H NMR and ¹³C NMR, IR as well as MALDI-TOF MS methods. It is revealed that at the terminal ends of the polymer chains there exist end groups of amide structures in addition to those observed previously. Possible mechanism for the formation of the amide end groups was provided.



Synthesis and Characterization of 3'-Deoxy-3'-fluoro-2'-O,3'-C-vinylene Linked Bicyclic Uridine^†

ZHAO Baojuan, YU Wenquan, CHANG Junbiao, LI Ertong, DING Qunshan, LI Fengjuan, CHEN Guangying, WANG Na

2014, 35(1):  58-62.  doi:10.7503/cjcu20130395

Asbtract ( )   HTML ( )   PDF (1186KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Synthesis of conformationally restricted nucleosides and oligonucleotides has received much attention in recent years. Moreover, it has been demonstrated that most nucleosides with fluorine in the sugar moiety possess potent antitumor and/or antiviral activities. However, to the best of our knowledge, there are few reports on conformationally restricted nucleosides with fluorinated sugar moiety. Herein, we report the design and synthesis of a novel fluorinated bicyclic nucleoside, 3'-deoxy-3'-fluoro-2'-O,3'-C-vinylene linked bicyclic uridine, via an eleven-step synthesis from D-xylose. The synthetic route involved ethynylation in the sugar ring, diethylaminosulphur trifluoride(DAST)-mediated fluorination and configuration inversion at the 3'-position to give the key intermediate 7, which then coupled with nucleobase, followed by deprotection and ring closure under basic conditions to afford the target compound 1. Its structure was characterized by ¹H NMR, ¹³C NMR and HRMS. A plausible mechanism for the formation of the key intermediate 7 was proposed. It could be rationalized by the neighbouring group participation of the 3-benzoate ester and the generation of the benzoxonium ion B. The present work provides an efficient tool for the construction of biologically interesting fluorinated bicyclic nucleosides and their analogues.



Synthesis and Properties of Spiro[dibenzo[a, j]xanthene-14,9'-fluorene]

CHEN Muzi, YOU Yongzhi, ZHANG Yong, LI Haiyan, FANG Wei

2014, 35(1):  63-67.  doi:10.7503/cjcu20130375

Asbtract ( )   HTML ( )   PDF (1995KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Spiro[fluorene-9,9'-xanthene](SFX) and its derivatives as the unit of organic optoelectronic materials have attracted much attention due to their promising thermal and photophysical properties. By tuning the conjugated degree and the steric of SFX, we designed a novel compound spiro[dibenzo[a,j]xanthene-14,9'-fluorene] and anticipated that it would have better performance than SFX. The reaction of 9H-fluoren-9-one and naphthalen-2-ol under the conditions of sulfuric acid and 3-mercaptopropanoic acid gave the target compound spiro[dibenzo[a,j]xanthene-14,9'-fluorene]. The compound was characterized by NMR, MS, IR spectra, elemental analysis and X-ray structural determination. The crystal data of the compound showed that a spiro ring was formed through the six-membered heterocyclic ring in dibenzo[a,j]xanthene sharing one carbon atom with the five-membered ring in fluorene. The photophysical and thermal properties were investigated by UV-Vis absorption, photoluminescence spectra, thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC). The maximum emission wavelength of the compound was found at 366 nm, and it showed a high thermal stability with a melting point of 297 ℃ and a decomposition temperature of 329 ℃. The results indicated that spiro[dibenzo[a,j]xanthene-14,9'-fluorene] could be used in the organic optoelectronic polymers to enhance their performance.



Synthesis, Characterization and Potential Electrochemical Properties of Novel Mn-Re Dinuclear Complexes Containing N-Heterocyclic Carbene-carbon Disulfide Ligands^†

ZHAO Jia, SUN Huabing, LIU Lingyan, CHANG Weixing, LI Jing

2014, 35(1):  68-74.  doi:10.7503/cjcu20130364

Asbtract ( )   HTML ( )   PDF (1717KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The ⅦB group organometallic compounds of Mn or Re have been widely investigated on the synthesis, characterization, possible reactivity properties and catalytic activities. Compared to the use of NHCs as ligands, the exploration in the field of carbene dithiocarboxylate(NHC·CS₂) coordination with metal is very lack. Herein reported the synthesis, characterization, reactivity and electrochemical studies of a series of Mn and Re organometallic complexes containing NHC·CS₂ ligands, concluding three mononuclear complexes and three dinuclear complexes. Those compounds were characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR. Compared to R₃P·CS₂ ligands, Mn-Re dinuclear organometallic complexes containing NHC·CS₂ ligands showed different reactivity. The electrochemical studies of [MnRe(CO)₆(μ-H){μ-CH₃SC(S)·IMes₂}] were explored, and the results showed it possesses the potential catalytic property for proton reduction of acetic acid to give hydrogen under electrochemical conditions, which may be considered as a model in the research of the active site of [Fe-Fe] hydrogenases.



Fitness of Taxadiene Biosynthetic Modules with Different S.cerevisiae Chassis^†

ZHANG Zhengwei, DING Mingzhu, YUAN Yingjin

2014, 35(1):  75-79.  doi:10.7503/cjcu20130416

Asbtract ( )   HTML ( )   PDF (1346KB) ( )  

Figures and Tables | References | Related Articles | Metrics

In the research works of constructing taxadiene aritficaial synthetic cell, S. cerevisiae is a commonly used chassis. The highest taxadiene yield in S.cerevisiae that has been reported was 8.7 mg/L. In this work, the fitness of different taxadiene biosynthetic modules with different S. cerevisiae chassis was studied to elevate the taxadiene yield to a higher level. We chose the S.cerevisiae strains BY4742 and the single knoc-kout strains of BY4742 as chassis, constructed the multi-plasmids taxadiene biosynthetic module by optimizing the mevalonic acid(MVA) pathway with tHMGR, importing the synthetic genes GGPPSsa and tTS, up-regulating and co-expressing the genes BTS1 and ERG20 which are correlated with the synthesis of geranylgeranyl diphosphate(GGPP). Then we redesigned and reconstructed the module inserted into a single CEN plasmid by the method of DNA assembler. Through fitting the different modules with different chassis, we acquired strains with diffe-rent taxadiene yields, the highest yield was 74.84 mg/L in the strain with the single-plasmid module and the chassis of YNL280C. The results indicated that the single-plasmid taxadiene biosynthetic module was more stable in the chassis than the multi-plasmids one, and the regulation of the pathways correlated with the MVA pathway will also influent the taxadiene yield.



Physical Chemistry

Thermal Stability of Novel Polyvinyl Formal Based Gel Polymer Electrolyte^†

GUAN Hongyan, LIAN Fang, WEN Yan, PAN Xiaorong, SUN Jialin

2014, 35(1):  80-84.  doi:10.7503/cjcu20130822

Asbtract ( )   HTML ( )   PDF (1351KB) ( )  

Figures and Tables | References | Related Articles | Metrics

A novel polyvinyl formal(PVFM) based gel polymer electrolyte(GPE) was prepared by means of initiator free in-situ thermal polymerization technology. The thermal stability of electrolytes was studied using differential scanning calorimetry(DSC). And the components of evolved gases from GPE and liquid electrolyte were comparatively analyzed by thermogravimetry-infrared spectrum/mass spectrometry(TGA-FTIR/MS) technique during the heating process. The results show that the macroscopic physical network formed by PVFM after polymerization can prevent the organic solvents from evaporating and reduce HF content at high temperatures effectively. Overall, PVFM based GPE is a promising electrolyte to achieve the enhanced thermal stability and improved safety.



Stability Mechanisms of Pickering Emulsion Co-stabilized by Silica Nanoparticles and PEO^†

TAN Weiqiang, ZANG Duyang, LI Yunfei, ZHANG Yongjian, LU Chenjun, LI Zhiguang

2014, 35(1):  85-91.  doi:10.7503/cjcu20130905

Asbtract ( )   HTML ( )   PDF (6073KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The Pickering emulsions with 65% water and 35% xylene system stabilized by silica nanoparticles or by both the particles and polyethylene oxide(PEO) additives were prepared. The emulsification was performed using a rotor-stator homogenizer under varied rotation speeds from 5000 r/min to 24000 r/min. The emulsion droplets were observed using an optical microscope, consequently, the droplet diameters vs. rotation speed and aging time were obtained. For most cases, W/O type emulsion was obtained. It is found that the mean diameter of water droplets decreases with increasing shear rate or shear duration. With the presence of PEO, the diameters of the droplets are significantly reduced and the phase inversion from W/O to W/O/W is prevented, which occurs in the system without PEO when prolong the shear duration. In addition, the coalescence of droplets is completely inhibited. To elucidate the ultrastability of the Pickering emulsion resulted from co-stabilization by silica nanoparticles and PEO, we study the rheological properties of the particle layers at the gas-liquid interface using the Langmuir trough equipped with a Wilhelmy plate. The silica nanoparticles were spreaded on the surface of either water or PEO water solution, consequently and the effect of PEO additives on particle layer properties was investigated. The results confirm that PEO additives can favor the trapping of particles at the water/xylene interface, due to the formation of larger size aggregates with the presence of PEO. Therefore, the particle layer has a higher compression modulus. The stronger mechanical property of the particle layer protects the water/xylene interface from rupture when exerted turbulent shearing, hence preventing the occurrence of phase inversion from W/O emulsion to the W/O/W one. Owing to the satisfaction of the Gibbs stability criterion, the coalescence of droplets is almost completely inhibited. The results demonstrate that the rheological properties of the liquid/liquid interface play an important role in the stability of Pickering emulsion.



Nb-modified Pd/Al₂O₃ Catalysts for Benzene Catalytic Combustion^†

HE Zhanfeng, WANG Dan, LIU Tao, WANG Huanyi, JIANG Yi

2014, 35(1):  92-97.  doi:10.7503/cjcu20130808

Asbtract ( )   HTML ( )   PDF (2265KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Pd/Al₂O₃ catalyst modified by Nb promoter was prepared and tested for benzene catalytic combustion. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed desorption of NH₃, H₂ temperature-programmed reduction, and N₂ adsorption. The results showed that the addition of Nb effectively improved the activity and stability of Pd/Al₂O₃ catalyst by increasing the dispersion of Pd active components, changing the oxidation state of partial palladium and increasing oxygen species concentration on the surface of catalyst. In case of Pd-Nb/Al₂O₃ catalyst, the benzene conversion of 90%was obtained at temperature as low as 195 ℃. Moreover, the 1%Pd-5%Nb/Al₂O₃ catalyst was more active than the 2%Pd/Al₂O₃ catalyst. It is concluded that Pd and Nb have a synergistic effect in benzene catalytic combustion.



Electrochemical Synthesis of Micro/nanostructured Poly(3,4-ethylenedioxythiophene) Films with Underwater Superoleophobicity^†

LIU Zhaoyuan, DING Chunmei, ZHU Ying, WAN Meixiang, JIANG Lei

2014, 35(1):  98-104.  doi:10.7503/cjcu20130800

Asbtract ( )   HTML ( )   PDF (5847KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Micro/nanostructured poly(3,4-ethylenedioxythiophene)(PEDOT) films were fabricated by an electrochemical polymerization in the presence of ionic liquid(1-hexyl-3methyllimidazolium bromide) as the electrolyte and dopants. The PEDOT films consist of micro-rod structures that encompass the micro-groove structure, and the nano-chain structure arranged inside of the micro-groove structure. The width of micro-grooves and the beads on the nano-chains can be adjusted by changing the current density of polymerization. The results showed that PEDOT chain backbone was doped by both the anion(Br^-) and cation(imidazolium) of ionic liquids. In addition, PEDOT film exhibited reversible electrochemical activity and underwater superoleophobic properties, which could be used for the application of the underwater anti-fouling coating and controlled oil-water separation materials.



Preparation of Copper Surfaces with Controlled Wettability Through the Molecular Self-assembling Process^†

DU Ying, CHEN Haijie, CHENG Zhongjun, LAI Hua, ZHANG Naiqing, SUN Kening

2014, 35(1):  105-109.  doi:10.7503/cjcu20130705

Asbtract ( )   HTML ( )   PDF (2544KB) ( )  

Figures and Tables | References | Related Articles | Metrics

We report a novel method for the fabrication of copper surfaces with controlled wettability. Through modification of the nanostructured copper substrates with mixed thiol molecules of HS(CH₂)₉CH₃ and HS(CH₂)₁₁OH, surfaces with controlled wettability from superhydrophobicity to superhydrophilicity can be achieved by simply controlling the concentration of HS(CH₂)₁₁OH in the modified solution. The controllability of the surfaces wettability can be ascribed to the combined effect of the surface chemistry variation and the hierarchical micro/nanostructures on the substrates. Especially the presence of hierarchical micro/nanostructures, which can provide a better control of the surface wettability between the two extremes: superhydrophobicity and superhydrophilicity.



Preparation of Co₃O₄ Nanosheet Supported on Ni Foam and Its Catalytic Performance for H₂O₂ Electroreduction^†

CHENG Kui, YANG Fan, YAN Peng, CAO Dianxue, YIN Jinling, WANG Guiling

2014, 35(1):  110-114.  doi:10.7503/cjcu20130504

Asbtract ( )   HTML ( )   PDF (2669KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Ni foam supported Co₃O₄ nanosheet(Co₃O₄/Ni foam) electrode was prepared by electrodeposition, followed by a thermal treatment in air. The nanosheet was characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectrometry(XPS) and Fourier transform infrared spectrometry(FTIR). The catalytic performance of the obtained electrode for H₂O₂ electroreduction in KOH solution was evaluated by means of linear scan voltammetry and chronoamperometry. The results show a current density of 0.386 A/cm² in the solution containing 3.0 mol/L KOH and 0.4 mol/L H₂O₂ at -0.4 V(vs. Ag/AgCl). The chronoamperometric current densities remain nearly constant with a 1000 s test. The results indicate that Co₃O₄/Ni foam has considerable activity and stability for H₂O₂ electroreduction.



Preparation of Phosphotungstic Acid-modified Carbon Supported Pd Catalyst and Its Electrocatalytic Performance for Formic Acid Oxidation^†

LU Liang, CHEN Tingting, GE Cunwang, TANG Yawen, CHEN Yu, LU Tianhong

2014, 35(1):  115-120.  doi:10.7503/cjcu20130469

Asbtract ( )   HTML ( )   PDF (3185KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Activated carbon was modified with phosphotungstic acid(PWA) at 80 ℃ in a water bath, Pd was then loaded on the PWA/C hybrid support to prepare Pd-PWA/C catalyst by a simple impregnation-reduction method. The measurements of energy dispersive X-ray spectroscopy(EDS), X-ray diffraction(XRD) pattern, transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS) indicate that phosphotungstic acid-modified carbon not only decreases the average size of Pd nanoparticles effectively but also interacts with Pd nanoparticles strongly. The electrochemical measurements demonstrate that the electrocataly-tic activity and stability of the Pd-PWA/C catalyst for formic acid oxidation are much better than that of the Pd/C catalyst. It is due to that the strong interaction between Pd and PWA/C not only decreases the adsorption strength and amount of CO at the catalyst electrode but also decreases the decomposition rate of formic acid to decrease the CO poisoning.



Volumetric Properties and Molecular Interactions of Binary Mixtures Imidazolium Acetates-ethanol at 293.15 K^†

HOU Haiyun, HUANG Yinrong, BAI Bofeng, YANG Jing

2014, 35(1):  121-126.  doi:10.7503/cjcu20130448

Asbtract ( )   HTML ( )   PDF (640KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Over the full molar fraction range and at 293.15 K, the densities of binary systems 1-methylimi-dazolium acetate([Mim]Ac)/1,3-dimethylimidazolium acetate([Mmim]Ac)/1-ethyl-3-methylimidazolium acetate([Emim]Ac)(1)-ethanol(EtOH)(2) were measured by pycnometer method. The apparent molar volumes of [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH, and the excess molar volumes of the binary mixtures were calculated. The relations of apparent molar volumes and molar fractions were fitted by three-parameter polynomials, from which, the limiting partial molar volumes and molar volumes were extrapolated. For [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH, the values of molar volumes from extrapolation and measurement are consistent with each other within ±0.07 and ±0.04 cm³/mol, respectively. The solvation coefficients at infinite dilutions of [Mim]Ac/[Mmim]Ac/[Emim]Ac and EtOH were calculated. The Redlich-Kister equation was used to fit the excess molar volumes and molar fractions. Finally, the solute-solvent pairs’ molecular interactions were discussed in terms of the limiting partial molar volume, the difference of molar volume and limiting partial molar volume, the solvation coefficients at infinite dilutions, and the excess molar volume. The results show that the sequence of molecular interaction at infinite dilutions of [Mim]Ac/[Mmim]Ac/[Emim]Ac is [Mim]Ac-EtOH>[Mmim]Ac-EtOH>[Emim]Ac-EtOH, and that at infinite dilutions of EtOH and [Mim]Ac/[Mmim]Ac/[Emim]Ac of x₁=0.15—0.95, the sequence is [Emim]Ac-EtOH>[Mmim]Ac-EtOH>[Mim]Ac-EtOH.



Photoelectrochemistry of Core-shell Nanostructure of Ordered ZnO Nanotube Array and Cu₂O Nanocrystals and Performance of the All Oxide Solid State Nanostructure Solar Cell^†

HAO Yanzhong, SUN Bao, LUO Chong, FAN Longxue, PEI Juan, LI Yingpin

2014, 35(1):  127-133.  doi:10.7503/cjcu20130425

Asbtract ( )   HTML ( )   PDF (5052KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Highly ordered ZnO nanotube arrays were prepared on the indium-tin oxide(ITO) glass substrate by a electrochemical method. Sequently, Cu₂O nanocrystals were electrodeposited onto the walls of the ZnO nanotube arrays to form the designed Cu₂O/ZnO 1D core-shell nanostructure. Cu₂O shell of different thickness was obtained by controlling the deposition coulomb of the Cu₂O nanocrystals. Scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD) were used to characterize the samples to confirm the formation of the designed nanostructures. A solid state solar cell with the designed Cu₂O/ZnO nanostructure as photoelectrode was fabricated. The effects of the Cu₂O shell thickness on the absorption and photoelectrochemical properties of the photoeletrode, as well as the photovoltaic performance of the designed solar cell, were investigated. The Au film thickness of the opposite electrode was also optimized. An energy conversion efficiency of 0.013% was obtained with the solar cell based on the photoelectrode of Cu₂O(1.5 C)/ZnO and the opposite electrode of Au(20—25 min, 4 mA)/Cu.



Effects of Electrolyte Flow Speed on the Performance of Zn-Ni Single Flow Batteries^†

SONG Shiye, PAN Junli, WEN Yuehua, CHENG Jie, PAN Junqing, CAO Gaoping

2014, 35(1):  134-139.  doi:10.7503/cjcu20130340

Asbtract ( )   HTML ( )   PDF (4788KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The effects of current density, zinc deposition area capacity and electrolyte flow speed on the performance of Zn-Ni single flow batteries and zinc deposition morphology were investigated by electrochemical measurements combined with SEM observation and XRD analysis. The results show that the zinc deposition area capacity is the most important factor which influences the charge-discharge performance of Zn-Ni single flow batteries and zinc deposition morphology. The electrolyte flow speed should be neither high nor low. With the zinc deposition area capacity increasing, the charge-discharge efficiency and the cycling stability of test cells are more sensitive to the change of current density. Meanwhile, the preferable electrolyte flow speed range becomes narrow. The spongy zinc deposition is exhibited at zinc deposition area capacity beyond 25 mA·h/cm². But, at low zinc deposition area capacity and low electrolyte flow speed, the spongy zinc deposition is relatively uniform and compact. While, at higher zinc deposition area capacity, clusters and particles turn into larger and their irregularity is more serious. Only at the moderate electrolyte flow speed of 7.1 L/min, the zinc deposition is partly compact and regular and the preferable charge-discharge performance of the cell is exhibited.



Electrodeposition Behavior of Chromium in Ionic Liquid [BMIM]P\begin{array}{c}{F_6}^{†}\end{array}

HASIMU Yushanjiang, LIU Ruiquan, MI Hongyu

2014, 35(1):  140-145.  doi:10.7503/cjcu20130278

Asbtract ( )   HTML ( )   PDF (3048KB) ( )  

Figures and Tables | References | Related Articles | Metrics

1-Butyl-3-methylimidazolium hexafluorophosphate([BMIM]PF₆) ionic liquid was synthesized by 1-chlorobutane, N-methylimidazole and KPF₆. The structure of ionic liquid was investigated by IR spectrum. The electrochemical window of [BMIM]PF₆ was determined to be 4.7 V at 85 ℃ by cyclic voltammetry. The electrochemical behavior of the[BMIM]PF₆-Cr(Ⅲ) electrolyte was studied. The reduction of chromium from Cr(Ⅲ) to Cr(0) in the solution is a one-step irreversible growth process which is controlled by diffusion. The cathodal transfer coefficient(α) is 0.023 and the cathode diffusion coefficient(D₀) is 1.142×10^-6 cm²/s. The electrodeposition of chromium on copper substrate from [BMIM]PF₆-Cr(Ⅲ) were experimented by potentiostatic method at -1.5 V. The surface morphology of chromium coating was characterized by means of scanning electron microscopy(SEM) and its morphology was granular structure. The size of granulae increase with the increase of deposition time. The chemical composition and structure of chromium coating were tested by energy dispersive spectrometry(EDS) and X-ray diffraction(XRD). The results indicate that the coating consist of amorphous metallic chromium.



Quantum Chemistry Calculation of Thermophilic Protease PH1704 Allosteric Center and Mutant Dynamics^†

ZHAN Dongling, GAO Nan, HAN Weiwei, FENG Yan

2014, 35(1):  146-153.  doi:10.7503/cjcu20130792

Asbtract ( )   HTML ( )   PDF (4094KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The PH1704 allosteric sites were studied with the quantum chemistry analysis and the crystal structure analysis. The results show that key residues are Arg113, Tyr120 and Asn129. Tyr120 is connected with nucleophilic residues Cys100 by a hydrogen bond, participates in enzyme nucleophilic catalyst, and is validated by fixed-point mutation of molecular biology experiments. The structures of four building protein of DJ-1 superfamily show that the 120 site locates in the substrate binding pocket in the subunit interface and affects the enzyme activity of the protein. The k_cat/k_m(L·μmol^-1·min^-1) value of mutant R113T/Y120P/N129D is six times higher than that of the wild-type and the Hill coefficient changes from 0.86(wild type) to 1.3 with negative cooperativity disappearing. The main reason is that the residue of 120 site changes from Tyr to Pro, and the hydrogen bonds between Tyr120 and Cys100 are broken, thus its nucleophilic attacking resis-tance decreases, which causes the enzyme activity to increase. The mutations of 113 and 129 sites lead to the detachment of the anionic allosteric agent, thus the negative cooperativity disappears. This work predictes the allosteric site of thermophilic protease by quantum chemistry and crystal structure analysis and provides a solid foundation for further research on the allosteric enzyme of DJ-1 superfamily.



Effects of Substituents on the Binding Energy in Hydrogen-bonded Complexes Containing Adenine and Thymine^†

LIU Peng, LI Shushi, WANG Changsheng

2014, 35(1):  154-160.  doi:10.7503/cjcu20130707

Asbtract ( )   HTML ( )   PDF (2601KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The optimal structures and binding energies of seventeen substitutional thymine and adenine hydrogen-bonded complexes were obtained theoretically and the effects of substituents on the binding energies were explored. The calculation results show that the interaction between trifluridine and adenine is stronger than that between thymine and adenine. This conclusion is in agreement with the fact that the association of trifluridine and adenine has precedence over the association of thymine and adenine. Compared with CF₃, three stronger electron withdrawing groups(SO₃H, CN and NO₂) can increase the binding energy between thymine and adenine, suggesting that the thymine substituted by these three groups may also provide a potential anticancer application. Atoms in molecules theory and the natural bond orbital analysis indicate that N—H…N hydrogen bon-ding is the strongest, N—H…O=C is stronger, while C—H…O=C is the weakest. Atoms in molecules theory and the natural bond orbital analysis also indicate that the orbital overlap interactions play a signi-ficant role in these hydrogen bonds.



Protection of LEA-motif for POPE Membrane During Desiccation^†

ZHAI Zhen, LI Daixi, ZHANG Yan, CHEN Zhenglong, LIU Baolin, LIU Li, YU Huaxing

2014, 35(1):  161-167.  doi:10.7503/cjcu20130675

Asbtract ( )   HTML ( )   PDF (3451KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Late embryogenesis abundant(LEA) protein is a kind of low molecular weight and high hydrophilic protein and the expressions of it are correlated with desiccation tolerance. Combined with their multitudinous biological functions, such as stabilizing membranes and proteins, scavenging free radicals and so on, LEA would be good and potential preotectant for biomaterials. However, the protective mechanism of LEA protein for membrane is not clear and definite, which results in the absence of abrupt development for the actual applications. Therefore, the drying process of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine(POPE) membrane with or without LEA-motif protectant at low temperature was thoroughly researched by molecular dynamics simulation. The results such as the 3D structure of POPE membrane, the lateral diffusion coefficient of POPE lipids, the order parameter of hydrophobic chains and the H-bonding interactions were analysized and compared between the two systems detailedly. The damage of POPE membrane and the bioactive protection of LEA-motif to the POPE membrane during desiccation were revealed from the microscopic view. The results indicate that LEA-motif can stabilize the structure of POPE membrane and then maintain the biological activity of biomaterials.



Computer Simulation of Micellization for Ring-like Block Copolymers^†

LI Liangyi, LI Zhanwei, FU Cuiliu, SUN Zhaoyan, AN Lijia

2014, 35(1):  168-174.  doi:10.7503/cjcu20130719

Asbtract ( )   HTML ( )   PDF (2296KB) ( )  

Figures and Tables | References | Related Articles | Metrics

The micellization behaviour of ring-like AB diblock copolymers in a selective solvent was compared with the corresponding linear ABA triblock copolymers via Monte Carlo simulation. The simulation results show that the difference in the critical micellization concentration(cmc) values between ring-like copolymers and linear copolymers with same compositions is closely related to the content of A blocks, f_A, and the strength of attractive interaction between B monomers, ε. When f_A is relatively small and ε is big, the cmc values of ring-like block copolymers are smaller than those of the corresponding linear ones; whereas when f_A is big and ε is small, the cmc values of triblock copolymers are smaller than those of the corresponding ring-like ones. To further understand the effect of f_A and ε on the micellization behavior, we calculated the entropy and the potential energy contributions to the micellization free energy, respectively. The results show that in the studied range of f_A and ε, the entropy loss in micellization for ring-like block copolymers is always smaller than that for triblock copolymers, so it seems that the micellization of ring-like block copolymers is always easier than that of the linear ones if we only consider the entropy contributions to the free energy. But if we calculate the potential energy contributions to the free energy, it can be found when f_A is relatively small and ε is big, the potential energy decreases greatly during the micellization of ring-like block copolymers. Considering the less unfavorable contribution of entropy part to the free energy for ring-like block copolymers, the micellization of ring-like block copolymers should be much easier than that of the linear ones. When f_A is big and ε is small, the potential energy decreases greatly when the micelles form for linear block copolymers. Although the entropic contribution to the free energy is unfavorable for linear ones, the potential energy still shows the dominative contribution to the free energy and therefore the micellization of linear block copolymers is much easier than the ring-like ones. The above analysis of the free energy will help us understand the micellization behavior of ring-like block copolymers and linear block copolymers.



Polymer Chemistry

Preparation and Characterization of Diethylene Glycol Octadecyl Ether Methacrylate and Its Polymer

ZHANG Zhili, TANG Xiaofen, MENG Jieyun, ZHANG Xingxiang, SHI Haifeng

2014, 35(1):  175-179.  doi:10.7503/cjcu20130881

Asbtract ( )   HTML ( )   PDF (930KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Diethylene glycol octadecyl ether methacrylate(DEGOEMA) as a phase change material was prepared by means of acrylation of diethylene glycol octadecyl ether sodium(C18E2Na) with methacryloyl chloride. And then poly(diethylene glycol octadecyl ether methacrylate)(PDEGOEMA) was synthesized by free radical polymerization. The molecular weight and its distribution were characterized using gel permeation chromatography(GPC). The structure, phase change properties, thermal stablility, crystal structure of the monomer and the comb-like polymer were characterized using Fourier transform infrared spectroscopy(FTIR), hydrogen nuclear magnetic resonance spectrum(¹H NMR), differential scanning calorimetry(DSC), thermogravimetric analysis(TG) and wide-angle X-ray diffraction(XRD). The results show that the novel monomer and polymers are excellent phase change materials with steady structure, high crystallinity, higher heat enthalpy and thermal stablility. Both the melting and crystallizing enthalpies of PDEGOEMA are 73 J/g. The onset melting temperature and crystallizing temperature are 41 and 36 ℃, respectively. It is thermal stable below 314 ℃. These properties indicate that this phase change material can be widely used as a polymeric phase change material in high processing and using temperature environments.



Polyimide Membranes Modified by Polyhedral Oligomeric Silsesquioxane

FAN Haibo, YANG Rongjie

2014, 35(1):  180-185.  doi:10.7503/cjcu20130812

Asbtract ( )   HTML ( )   PDF (2958KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Four kinds of polyimide(PI)/Si membranes were prepared using PI with octaphenylsilsesquioxane(OPS), octa(aminophenyl)silsesquioxane(OAPS), polyphenylsilsesquioxane(PPSQ) of ladder structure, and nano-silica(SiO₂), respectively. Their morphologies were studied by scan electron miscroscope(SEM) and the mechanical properties were measured by tensile testing and the thermal properties were studied by differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and limited oxygen index(LOI). The SEM and XRD results of the PI/Si composites proved that there were good compatibility between PI and OAPS because the aminophenyl groups in OAPS could participate in the polymerization process of PI. The mechanical properties of PI/OAPS membrane were nearly the same with that of PI. And the addition of OPS or PPSQ decreased the PI mechanical properties sharply. DSC analysis implied that the additives could increase the glass-transition temperature(T_g) a little and the T_g of PI/OAPS was the highest because the Si—O caged structures existed in the PI main chain. The addition of OAPS, PPSQ or SiO₂ would improve the thermal stability a little according to the TGA results. One interesting result is that the LOI of PI/Si membranes significantly increased compared with pure PI membrane. The LOI for PI/OPS membrane was 57%, while that for PI was 46.5% only. The improvement was caused by the formation of a well covered silicate char structures after burning. And the LOI of the membranes of PI with polyhedral oligomeric silsesquioxanes are higher than PI/SiO₂.



Synthesis of Polystyrene Modified with Sulfonyl and Extraction for Aromatics^†

YU Huanyang, CUI Ying, LIU Xianying, SHI Zuosen

2014, 35(1):  186-190.  doi:10.7503/cjcu20130794

Asbtract ( )   HTML ( )   PDF (1296KB) ( )  

Figures and Tables | References | Related Articles | Metrics

A series of sulfonated low molecular weight polystyrene(LOPSS) was synthesized via radical polymerization, oxidation of end-group and Friedel-Crafts acylation reactions. The structures of obtained polymer were investigated by ¹H NMR, FTIR and thermal behavior of polymers was performed by differential scanning calorimetry(DSC) and thermo gravimetric analyzer(TGA). The selectivity for aromatic hydrocarbons was tested through extraction of aromatics from aromatic/aliphatic hydrocarbons. The results indicated that with the increase of sulfonylation degree, selectivity coefficient and distribution coefficient of toluene obviously increased. Polystyrene modified with polar monomer has good selectivity for aromatics from all kinds of aromatic/aliphatic hydrocarbons.



Fabrication and Medical Imaging of Ultrasonic Imaging Nanocaspsules^†

HUANG Chaofan, QU Guanxiong, WEI Zhenhua, XU Bin, DING Jing, DOU Hongjing, SUN Kang

2014, 35(1):  191-198.  doi:10.7503/cjcu20130690

Asbtract ( )   HTML ( )   PDF (3205KB) ( )  

Figures and Tables | References | Related Articles | Metrics

Poly(lactic acid)-b-poly(ethylene glycol)(MePEG-b-PLA) based nanocapsules containing per-fluorohexane were fabricated through a double emulsion-solvent evaporation method. In the preparation, three kinds of hydrophilic polymers, i.e., poly(vinyl-alcohol)(PVA), chitosan(CS), and carboxymethyl dextran(CMG) were used as emulsifier or co-emulsifier to modify the surface of nanocapsules. Besides, two kinds of MePEG-b-PLA copolymers with different block length ratio were used as main shell composition to fabricate nanocapsules. Nanocapsule size, morphology, zeta potential, water stability of six nanocapsule samples fabricated by different polymers or emulsifiers were characterized by Malvern nanosizer analyzer, transmission electron microscope(TEM) and UV-Visible spectrophotometer(UV-Vis), respectively. The results showed that nanocapsules using 1%PVA+1%CMG as an emulsifier and MePEG-b-PLA[m(MePEG)∶m(PLA)=1∶3] as shell material had monodispersed small size and stable water property. These nanocapsules are not only in nanometer-scale but also possess favorable ultrasonic imaging property. Ultrasonic imaging property of nanocapsules was charaeterized using in vitro ultrasound tester and made a comparison with a commercialized ultrosonic imaging agent SonoVue^TM. The results demonstrated a brighter contrast scale and edurable ultrasonic property of MePEG-b-PLA nanocapsules. In addition, the cytotoxicity by incubating MePEG-b-PLA nanocapsules with rat liver cells line BRL-3A was characterized through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. The results showed that the PLA-based nanocapsules imposed no significant inhibition effect on proliferation of BRL-3A cells.



Synthesis and Flame Retardancy of Novel Thermally Stable Poly(imideurethane)s Containing Imide and Alkynyl Groups in Main Chain

TANG Qiheng, AI Qingsong, YANG Rongjie, HE Jiyu

2014, 35(1):  199-204.  doi:10.7503/cjcu20130586

Asbtract ( )   HTML ( )   PDF (1088KB) ( )  

Figures and Tables | References | Related Articles | Metrics

A kind of glycol containing imide and alkynyl function was synthesized from pyromellitic dianhydride(PMAD), butynediol(2-butyne-1,4-diol) and D,L-phenylalanine(DLP). Linear imide and alkynyl modified thermoplastic poly(imide-urethane)s were prepared by the obtained glycol, 4,4'-diphenylmethane diisocyanate(MDI) and poly(tetrahydrofuran)(PTMG) via prepolymerization. The poly(imide-urethane)s structures were characterized with Fourier transform infrared spectroscopy(FTIR), universal testing machine tension, thermalgravimetric analysis(TGA), wide-angle X-ray diffraction(XRD). The results showed that the novel thermoplastic poly(imide-urethane)s elastomer with amorphous structure were successfully synthesized. The tensile strength increases with the hard segment contents. Comparing with the conventional thermoplastic polyurethanes extended by 1,4-butanediol, the poly(imide-urethane)s show slower thermal degradation rate during the degradation process. The polymers with different hard segments contents all reach a UL-94 V-2 rating, and the limiting oxygen index(LOI) value increases with different hard segments contents.