Table of Content

10 February 2015, Volume 36 Issue 2

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Cover and Content of Chemical Journal of Chinese Universities Vol.36 No.2(2015)

2015, 36(2):  0-0. 

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Review

Self-assembly of Peptide Amphiphiles and Their Applications^†

WANG Jianxun, QIN Siyong, CAI Tengteng, ZHANG Xianzheng, ZHUO Renxi

2015, 36(2):  201-211.  doi:10.7503/cjcu20140859

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Due to good biocompatibility, straight forward chemical modification and inherent molecular recognition, peptides have been very attractive biological building blocks for self-assembly. Amphiphilic peptides are of special interesting with the advantages of abundant molecular structures, unique structures of assemblies and special biological functions. In this work, the recent progress in the study and application of the self-assembly of amphiphilic peptides was reviewed. Several kinds of amphiphilic peptides were introduced. Moreover, the molecular structures of amphiphilic peptides, the behavior and mechanism of self-assembly, the structure and property of assemblies and their applications in nanotechnology and biomedical field were also demonstrated in detail.



Letter

Thermodynamic and Kinetic Parameters of in-situ Photocatalytic Process with Different Morphologies of Ag₃PO₄ and Their Free Energy^†

LIU Zuojiao, FAN Gaochao, LI Xingxing, TAN Xuecai, ZHONG Lianyun, HUANG Zaiyin

2015, 36(2):  212-214.  doi:10.7503/cjcu20140947

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A self-designed photomicrocalorimeter was applied to obtain in-situ thermodynamic and kinetic information on photocatalysis degradation of methylene blue(MB) over different morphologies of Ag₃PO₄. The molar surface Gibbs free energies(\begin{array}{c}{G}_m^s\end{array}) of the prepared Ag₃PO₄ were obtained based on the thermokinetic theory and microcalorimetry. The acquired in-situ thermodynamic and kinetic information of the photocatalytic process was successfully associated with \begin{array}{c}{G}_m^s\end{array} and catalytic performance of the prepared Ag₃O₄ catalyst with different morphologies. The results revealed that the heat effect and enthalpy change rate of the tetrapod, cube and dodecahedron Ag₃PO₄ increased in order, whereas the \begin{array}{c}{G}_m^s\end{array} and catalytic performance of the tetrapod, cube and dodecahedron Ag₃PO₄ decreased in order.



Articles: Inorganic Chemistry

Synthesis and Characterization of Coordination Polymers Based on 5-Azidoisophthalic Acid^†

MA Benhua, PENG Yu, HUA Jia, SHI Zhan

2015, 36(2):  215-220.  doi:10.7503/cjcu20140957

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Four coordination polymers, Co(aip)(py)₃(1), Co(aip)(4,4'-bipy)(2), Mn(aip)(4,4'-bipy)(3) and Mn(aip)(dptz)(4)[Py: pyridine; 4,4'-bipy: 4,4'-dipyridyl; dptz: 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine] were synthesized by the reaction of 5-azidoisophthalic acid(H₂aip) and auxiliary ligands with transition metal. The structures of the complexes were characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, infrared spectroscopy and thermal-gravimetric analysis. The structural analyses of compound 1 show that the complex belongs to the monoclinic system, and the space group is C2/c with a 1D chain structure. Compounds 2 and 3 belong to the monoclinic system, and the space group is C2/m with 2D network structures. For compound 4, the space group is P\begin{array}{c}\overline{1}\end{array} with a 2D network. The magnetic properties were also characterized. The results reveal that anti-ferromagnetic interaction exists in compounds 1—4.



Effect of Ultrasonic Time for Graphite Oxide on the Structure and Super Capacitor Performance of Three-dimensional Reduced Graphene Oxide^†

WANG Jiande, PENG Tongjiang, XIAN Haiyang, SUN Hongjuan, HOU Yundan

2015, 36(2):  221-228.  doi:10.7503/cjcu2014086

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Three-dimensional reduced graphene oxide(3DRGO) was prepared from graphene oxide(GO) with different ultrasonic time by one-step hydrothermal method. X-Ray diffraction(XRD), Raman spectroscopy, atom force microscopy(AFM), scanning electron microscopy(SEM) and elctrochemical measurements were used to investigate the structure and supercapacitive performance of 3DRGO. The results show that when the ultrasonic time is less than 120 min, stabilized three-dimensional structure can be formed in the hydrothermal reduced graphene oxide. Along with the increase of the ultrasonic time, the size of 3DRGO decrease while the strength increase, and the inner structure of 3DRGO transforms from schistose to network. When the ultrasonic time is longer than 120 min, the stability of the network in 3DRGO is inferior on a macro level. The results of electrochemical measurements show that all the 3DRGO samples prepared with different ultrasonic time have good supercapacitive performance. The sample prepared with 120 min has the best supercapacitive performance for its well-proportioned network. The capacity can reach 328 F/g at the current density of 1 A/g and 240 F/g at the high current density of 20 A/g.



Preparation of NaP Zeolite with Low Si/Al Molar Ratio from Flying Ash^†

CHEN Yanguang, XIE Conghao, HAN Hongjing, ZHAO Fajun, WANG Baohui

2015, 36(2):  229-235.  doi:10.7503/cjcu20140845

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Taking Na₂SiO₃ and NaAlO₂ obtained from flying ash by staged treatment as raw material, NaP zeolite was prepared via hydrothermal method. The influences of organic steric agents and sodium salts with different anions on the preparation of NaP zeolite were investigated. The synthetic parameters of the hydrothermal system for NaP zeolite were optimized. The crystal form, morphology and pore volume of the NaP zeolite were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and Brunauer-Emmett-Teller(BET) surface analysis, respectively. The adsorption performance of the NaP zeolite in Ni²⁺-containing solution was evaluated. The results show that the optimal parameters for the preparation NaP zeolite are as following: n(Na₂O)∶n(SiO₂)∶n(Al₂O₃)∶n(H₂O)=1.66∶1∶0.51∶116, the reaction temperature is 120 ℃, crystalization time is 8 h. Br^- is in favor of improving the purity and increasing the yield of NaP zeolite. With the addition of triethylolamine(TEA), the grain size of NaP zeolite becomes smaller and the pore volume is enlarged. The maximum removal rate for Ni²⁺ is about 96.2%.



Analytical Chemistry

On-line Detection of Volatile Sulfur Compounds in Breath Gas by Proton Transfer Reaction Mass Spectrometry^†

SHEN Chengyin, WANG Hongmei, HUANG Chaoqun, LU Yan, XIA Lei, CHEN Xiaojing, WANG Hongzhi, CHU Yannan

2015, 36(2):  236-240.  doi:10.7503/cjcu20140794

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To develop a kind of noninvasive method of breath diagnosis in diseases, much attention has been paid to the study of the relation between diseases and volatile organic compounds in human breath gas. However, the gas in oral cavity was usually ignored in many studies of breath gas. The bad breath odor of a participant was studied by a home-made proton transfer reaction mass spectrometer(PTR-MS). The breath via the mouth, breath via the nose and the air in the mouth cavity were monitored with the mode of multiple ion detect scans. The results show that three different volatile sulfur compounds that cause bad breath odor should be attributed to different sources. The source of methyl mercaptan in breath is oral cavity, and the source of hydrogen sulphide and dimethylsulfide in breath is lung or respiratory tract. The related result is very important to sampling and detection of breath gas.



Sensor Array Based on MTPP-AuNPs Compounds for Fast Identification of Organic Small Molecules in Exhaled Breath of Lung Cancer Patients^†

XU Yonghong, HUO Danqun, FA Huanbao, YANG Mei, HOU Changjun

2015, 36(2):  241-247.  doi:10.7503/cjcu20140648

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The smaller gold nanoparticles(AuNPs) were synthesized and used as a protectant for metal tetraphenylporphyrins(MTPP), and a 6×6 sensor array was constructed together by AuNPs-MTPP compounds and pH indicators to detect 12 organic small molecules(OSMs) in exhaled breath of lung cancer patients with three concentration gradients, and each test was repeated five times. The protective effect showed that the stability and sensitivity of the array were significantly enhanced due to the introduction of AuNPs; hierarchical cluster analysis(HCA) indicated that the results of five parallel experiments gathered into a cluster firstly, and target objects with similar structure were gotten together subsequently; digital color difference maps of OSMs with different kinds and concentrations visually displayed that the proposed method had good capability for qualitative and semi-quantitative analysis. The method can be used for fast identification of OSMs and has potential application prospect in lung cancer screening.



Novel Purification Method for Isotopically Enriched Molybdenum and Determination of Its Mass Fractionation Effect^†

SONG Panshu, WANG Jun, REN Tongxiang, ZHOU Tao, LU Hai

2015, 36(2):  248-253.  doi:10.7503/cjcu20140631

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A novel purification method for isotopically enriched molybdenum was established according to the differences in sublimation temperature of MoO₃ comparing with other species. The oxidation time, sample volume and sublimation temperature in this procedure were optimized using Synthetic-Mo with nature Mo compositions. As measured by HR-ICP-MS, Mo could be effectively separated from other matrix elements, and the purities of ⁹⁵Mo and ⁹⁸Mo were 99.992% and 99.990%, respectively, after purification. Isotopic compositions of Synthetic-Mo and Purified-MoO₃ samples were determined by MC-ICP-MS, their \begin{array}{c}{{\delta }^X}^{/95}\end{array}Mo(X=92, 94, 97, 98, 100)values were indistinguishable within analytical uncertainty(<0.3‰), revealing that isotopic fractionation of Mo was unlikely during purification. The proposed purification method is of great importance in developing high-accuracy measurement method for isotopic compositions of Mo.



Facile Fabrication of SERS-based Microchannel Device for Hazardous Chemical Analysis^†

YANG Yongan, XU Shuping, WANG Yuyang, QI Guohua, XU Weiqing

2015, 36(2):  254-259.  doi:10.7503/cjcu20140621

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Surface-enhanced Raman scattering(SERS)-based microchannel device was fabricated by self-assembling silver colloids. The detection limits of the device for rhodamine 6G(R6G) and 4-mercaptopyridine(4-MPY) were as low as 10^-11 and 10^-8 mol/L, respectively, therefore, the device is a very efficient SERS-active substrate. Furthermore, two hazardous chemicals, Thiram and Melamine, were detected by the microchannel device. The detection limits for Melamine and Thiram were 10^-6 and 10^-7 mol/L, respectively. The results show that the microchannel device can be used to analyze these two harmful chemicals. It can be used as a miniature SERS sampling setup to detect trace amount of chemicals and for on-line or in-situ detection, and have the potential for the microanalysis of liquid chemicals.



Organic Chemistry

Molecular Full-adder and Full-subtractor Logic Circuit Based on Fluorescein Derivatives^†

TIAN Tao, LIU Chang, HE Song, ZENG Xianshun

2015, 36(2):  260-266.  doi:10.7503/cjcu20140668

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Over the past decade, there has been significant progress in the development of molecular compu-ter, which has inspired scientists to construct appropriate molecular systems that could integrate simple logic gates into combinatorial circuits. In this work, a novel fluorescein-based QHF⁺ with five-state molecular switch was synthesized. The conversion of the five states of QHF⁺ was observed by UV-visible absorption spectra under various pH values in CH₃CH₂OH/H₂O(volume ratio 1∶1). Spectral responses with the use of chemical inputs in the form of H⁺ and OH^- revealed that QHF could function as a combinatorial logic circuit(XOR gate and INHIBIT gate, AND gate and XOR gate). Absorbance change at 424 and 490 nm or transmittance change at 424 nm, was monitored as output signals with threshold value of A=0.209(or T=61.8%). When absorbance intensity or transmittance percentage was more than the threshold value, the output signal was 1. Otherwise, the output value was 0. In conclusion, a full-subtractor was achieved by setting the initial state to QHF⁰ with outputs at 424 and 490 nm in the absorption mode, while a molecular full-adder was provided by setting the initial state to QHF⁺ and observing both absorbance at 490 nm and transmittance at 424 nm.



Malononitrile and Cyanoacetic Acid Esters Involved Cascade Reaction of (-)-Methyl 3-Dehydroshikimate^†

WANG Dejian, ZHANG Ensheng, XU Tianlong, LI Jun, HUANG Tongkun, ZOU Yong

2015, 36(2):  267-273.  doi:10.7503/cjcu20140656

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With the diminishing of fossil oil reserves, chemical conversion and value-added utilization of renewable biomass have become a worldwide topic for chemists. It was demonstrated that the reaction between (-)-methyl 3-dehydroshikimate(3-MDHS) and several active methylene compounds under facile conditions gave rise to substituted 2-aminobenzofurans in moderate to good yields. The process involved the formation of a new C—C bond through condensation, followed by a sequential aromatization/cyclization reaction. The chemoselective hydrolysis of compound 3a was also realized. The structures of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR, MS and IR. The ready availability of biosourced starting materials, the convenient reaction conditions as well as the easy workup procedures made this protocol a practical method for the chemical conversion of the renewable biomass (-)-shikimic acid.



Biomimetic Synthesis of Natural Product Tryptanthrin and Its Derivatives^†

WANG Cuiling, HOU Baolong, ZHANG Ning, SUN Yanni, LIU Jianli

2015, 36(2):  274-278.  doi:10.7503/cjcu20140653

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Tryptanthrin possesses remarkable antitumor, anti-inflammatory and antibacterial activity as one of the active ingredients in medicinal plants Strobilanthes cusia, Polygonum tinctorum Lour and Isatis Einetorial. However, despite a variety of synthesis methods had been developed, the yield was low, and the cost was high due to the use of isatoic anhydride. Furthermore, not a single current synthesis method is efficacious and simple enough to meet the requirement for the use in lab and industry. Our previous study on the distribution of tryptanthrin in Isatis Einetorial demonstrated that tryptanthrin was a product resulted from the reaction between isatin and anthranilic acid in the leaves during a drying process instead of a constitutive component within the plant. In order to develop an efficient and simple method, a biomimetic synthesis of tryptanthrin was carried out using isatin and anthranilic acid existing naturally in the medical plants as reaction agents, with THF and toluene as solvents in the presence of catalyst POCl₃. A high yield of 40.3% was obtained, and the product showed a structure characterization same to that of standard sample. After the first trial, total other 14 derivatives of tryptanthrin were synthesized using the same method with relatively reasonable yields. Moreover, the raw materials used in this study were readily available and much cheaper than those in conventional methods, and the reaction conditions were relatively mild. It implied that the synthesis method reported could be applied widely.



Design, Synthesis and Biological Activity of Acid Sphingomyelinase Inhibitors^†

YANG Kan, ZHANG Kuojun, HU Songyuan, GU Qinlan, DONG Jibin, WANG Jinxin

2015, 36(2):  279-286.  doi:10.7503/cjcu20140617

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Acid sphingomyelinase(ASM) plays an important role in sphingolipid catabolism, which catalyzes the hydrolysis of sphingomyelin to ceramide and phosphorylcholine. Ceramide serves as one of the most important second messengers, and there is growing evidence shows that ASM activation and ceramide accumulation are involved in the development of various common human diseases. Nevertheless, only few inhibitors directly and selectively interacted with ASM. According to the reported inhibitors and their suppressive activity of ASM, 3D-pharmacophore model of ASM inhibitors based on ligands was built for the first time. Due to potent inhibitory ASM activity of α-Mangostin, a phytochemical content derived from garcinia mangostana linn, it was chosen as the lead compound for structure optimization. Then 11 new ASM direct inhibitors were designed and synthesized successfully. Their structures were confirmed by ¹H NMR, ¹³C NMR and mass spectrometry. Preliminary activity screening results in vitro showed that the compounds Ⅰb,Ⅰd,Ⅰe and Ⅰf had potent ASM inhibitory activity. The ASM inhibition rate of compoundⅠf was 88.9%. The structure-activity relationship indicated that the introduction of chain amino would influence the ASM activity obviously and removal of alkenyl had little impact on the ASM activity. This result will play a guiding role for designing better ASM inhibitors and proceeding basic research of ASM.



Synthesis of New Water-soluble Derivatives of Indolizine and Their Applications as Fluorescence Sensors for C\begin{array}{c}{u^{2+}}^{†}\end{array}

KONG Weiwei, JIANG Yuliang, HAN Qiaorong, WANG Bingxiang

2015, 36(2):  287-292.  doi:10.7503/cjcu20140592

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Two new quaternary ammonium salts of indolizine derivatives 4a(1-{2-[N'-(3-cyano- indolizine-1-carbonyl)-hydrazino]-2-oxo-ethyl}-pyridinium; chloride) and 4b(1-{2-[N'-(3-Cyano-indolizine-1-carbonyl)-hydrazino]-2-oxo-ethyl}-2-methyl-pyridinium; chloride) as fluorescent sensors for Cu²⁺ were synthesized. The structures of the two compounds were determined by IR, ¹H NMR, MS and elemental analysis. Their UV and fluorescence spectra were measured. The influences of sixteen metal ions such as Cu²⁺, Zn²⁺, Ca²⁺, Cr³⁺, Co²⁺, Al³⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺, Fe³⁺, Cd^{2 +}, Mg²⁺, Pb²⁺, Li⁺ and Ag⁺ on their fluorescence properties were studied. Spectroscopic studies revealed that the two compounds had rather strong affinity toward Cu²⁺. The specificities of the two probes toward Cu²⁺ were determined. Compound 4a nearly no fluorescence intensity changes were observed in emission spectra together with Zn²⁺, Ca²⁺, Co²⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺,Cd²⁺, Mg²⁺, Pb²⁺, Li⁺ and Ag⁺, respectively. Compound 4b nearly no fluorescence intensity changes were observed in emission spectra together with Zn²⁺, Ca²⁺, Cr³⁺, Co²⁺, Al³⁺, Mn²⁺, Ni²⁺, Ba²⁺, Hg²⁺, Cd²⁺, Mg²⁺, Pb²⁺, Li⁺and Ag⁺, respectively. However, under identical conditions, the results showed that compounds 4a and 4b had fluorescence quenching together with Cu²⁺. So we have developed two new fluorescent sensors(4a and 4b). They showed high sensitivity and selectivity toward Cu²⁺ in aqueous solution.



Two Types of Carbon Dots with Excitation-dependent Emissions and Their Application as Anti-counterfeit Ink^†

NIE Hui, LI Minjie, JU Bo, ZHANG Sean Xiaoan

2015, 36(2):  293-298.  doi:10.7503/cjcu20140559

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Carbon dots with excitation-dependent emission were prepared using different chlorohydrocarbon and amine as reactants under the same reaction condition. The carbon dots 1 and carbon dots 2 had selective emissions in a range of 423—556 nm and 460—555 nm, respectively, in addition, their fluorescence intensity changes could be modeled by a Gaussian-like curve with the red shift of excitation wavelengths(denoted as type Ⅰ carbon dots). The carbon dots 3 had emissions in a broad color range over the entire visible region(407—670 nm), moreover, their fluorescence intensities had irregular change with the excitation wavelengths(denoted as type Ⅱ carbon dots). Then, fluorescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and infrared spectroscopy were explored to analyze their structural and spectral characteristics in detail. For the type Ⅱ carbon dots, except for the size effect, the surface functional groups, such as C=O and C=N, could efficiently introduce new energy levels for electron transitions and result in the continuously adjustable full color emissions. Further, the type Ⅱ carbon dots were demonstrated as ideal candidates for high security anti-counterfeit purpose.



Isolation, Structural Characterization and IEC-6 Cell Migration Activities of Polysaccharides From Atractylodes Macrocephala Koidz^†

WANG Yiyu, LIU Jiawei, SIMA Zhenhua, SONG Houpan, LI Ruliu, CAI Jiazhong, CHEN Weiwen

2015, 36(2):  299-305.  doi:10.7503/cjcu20140515

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Bioassay-guided fractionation led to isolation of a new polysaccharide YY13008 from the roots of Atractylodes macrocephala Koidz by aqueous extraction, ethanol precipitation and purification followed by column chromatography on DEAE-cellulose and sephadex LH-20. The chemical structure of polysaccharide YY13008 was then elucidated on the basis of acidic hydrolysis, environmental scanning electron microscope and spectroscopic data, including IR, 1D and 2D NMR analysis. The polysaccharide YY13008 was determined as homogeneous, with a molecular weight of 6546, as determined by a gel permeation chromatography-multi-angle laser light scattering(GPC-MALLS) method. The polysaccharide YY13008 was found to be a fructan containing almost exclusively a(2→1) -linked β-D-fructofuranosyl repeating units with terminal α-glucopyranosyl unit. The in vitro wound healing assays revealed that the treatment of polysaccharide YY13008 with difluoromethylornithine(DFMO), a specific inhibitor of ornithine decarboxylase, was able to completely reverse DFMO-induced inhibition of IEC-6 migration, however, the treatment of YY13008 alone did not affect the basal rate of IEC-6 migration.



Inclusion Complexes of γ-Cyclodextrin with Pendimethalin^†

YU Chi, FAN Tengfei, GUO Xinyu, WU Xuemin

2015, 36(2):  306-309.  doi:10.7503/cjcu20140316

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Through the saturated water solution method, the guest body pendimethalin was tried to be inclu-ded by the host body γ-cyclodextrin(γ-CD). Ultraviolet spectrum was used to determine the inclusion ratio in accordance with the Job’s method, clarified that the inclusion molar ratio was 1∶1. Infrared spectrum proved that the benzene ring structure of the pendimethalin could be entered into the γ-CD’s hydrophobicity cavity. The melting point of the pendimethalin was proved to be increased after the inclusion by thermal analysis. The emergence of the new diffraction peaks in powder X-ray diffraction atlas was attributed to the formation of new phase. The appearance of the inclusion was intuitively showed by the scanning electron microscopy(SEM). All of the results above indicated that the γ-CD-pendimethalin inclusion complex were obtained, and the equilibrium constant K was 1123.99 L/mol. Both the melting point and the solubility of the pendimethalin were significantly improved by including, therefore, pendimethalin could be processed into water-based pesticide formulations in the form of the inclusion.



Physical Chemistry

Factors Influencing the Shear Modulus of Colloidal Crystals^†

QIN Yanming, ZHOU Hongwei, XU Shenghua, SUN Zhiwei

2015, 36(2):  310-315.  doi:10.7503/cjcu20140959

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Home-made torsional resonance spectroscopy was used to study the shear modulus of colloidal crystals formed by different particles at different volume fractions, while reflection spectrum was used to measure the corresponding crystal structure and internal voids etc. at the same time. The results indicate that shear modulus increases with volume fractions for colloidal crystals formed by same particles. And for colloidal crystals formed by different particles, the shear modulus has a tendency to increase with the increase of the fraction of internal voids for the same particle number density. Further analysis of the experimental results and the comparison with the theoretical analysis shows that the main factor influencing the shear modulus is the nearest interparticle distance, which explains the experimental findings.



Molecular Simulation of Effects of Impurities on Flue Gas Separation in Metal-Organic Frameworks^†

WANG Jiachen, TONG Minman, SHAN Chao, XIAO Gang, LIU Dahuan, YANG Qingyuan, ZHONG Chongli

2015, 36(2):  316-324.  doi:10.7503/cjcu20140802

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The resulting excessive release of CO₂ into the atmosphere has triggered great change in the climate which calls for urgent cuts in the emission of such primary anthropogenic greenhouse gas. In this regard, one significant challenging separation problem nowadays is associated with the selective CO₂ capture from the flue gas emitted by large stationary point sources such as power plants. In this work, a computational study was performed to systematically investigate the effects of impurities(H₂O, O₂ and SO₂) on the performance of five metal-organic frameworks(MOFs)[ZIF-8, NOTT-300, UiO-66(Zr), UiO-66-NH₂ and UiO-66-2COOH] for the separation of flue gas under the industrial conditions, and the underlying microscopic mechanisms were also explored. The accuracy of the force fields adopted was verified by comparing the simulated adsorption isotherms with those experimental data. Then, molecular simulations were performed to investigate the separation behavior of flue gas consisting of CO₂, N₂, O₂, SO₂ and H₂O in these materials. The results show that O₂ and SO₂ have a negligible influence on the CO₂/N₂ selectivity of the MOFs. Water has a negligible effect on the separation performance of ZIF-8 and UiO-66(Zr) and can enhance the CO₂/N₂ selectivity of NOTT-300 and UiO-66-NH₂. However, the separation ability of UiO-66-2COOH is weakened in the presence of water. The current study demonstrates that the UiO-66-2COOH can be a promising candidate for selective CO₂ separation from dried flue gas, while UiO-66-NH₂ can be a good candidate for the separation of moist flue gas. The information obtained in current study could provide a theoretical guidance for the design of novel CO₂ capture materials.



Transition State Investigation on Hydrosilylation of Ketoimines with Trichlorosilane Using Asymmetric-axle-supported Chiral N-O Amides^†

PAN Wei, MA Wenguang, YANG Xiaodong, ZHENG Junye, SONG Biqing, NIU Yongzhi, GU Ji, HU Dongbao, YANG Qin, ZHU Huajie

2015, 36(2):  325-329.  doi:10.7503/cjcu20140791

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The mechanism was investigated for enantioselective hydrosilylation of C=N with HSiCl₃ catalyzed by a novel asymmetric-axle-supported chiral ligand with Hartree-Fock(HF) and density functional theory(DFT) at the 6-31G(d) basis sets, respectively. Molecules of catalyst, ketoimine and HSiCl₃ were included in activation energy computations. The energy barriers can well explain the enantioselective reaction e.e. values recorded in experiments. Also, a simplified transition state(TS) model was adopted in TS calculations, the barrier sequence recorded by the model had a good agreement with the results via using whole substances[catalyst 3 or epi-3, SiHCl₃ and (-)-N-(1-phenylethylidene)aniline] in TS calculations, including the e.e. values.



Effect of Substrate Material on the Immobilization of Multifunctional Amylase^†

XIA Ying, CAO Hao, ZHANG Yingjiu

2015, 36(2):  330-335.  doi:10.7503/cjcu20140767

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The catalytic site of the multifunctional amylase OPMA-N occupied a relatively large region in OPMA-N molecule. The optimal conditions to immobilize OPMA-N with hydrogel microspheres of chitosan as a carrier were established by orthogonal experiment as follows: 20 mg/mL glutaraldehyde served as cross-linking agent, at 25 ℃, pH=6.5 for 1.5 h, but as long as after the introduction of the substrate-mediated protective effect and conformational memory in order to obtain a stabilized immobilized OPMA-N(IOPMA-N). This highlighted the importance of the protective effect of the substrate in the immobilization process of the multifunctional enzymes such as OPMA-N in which the catalytic site-covering region generally occupies a larger region in OPMA-N molecule. Compared with the free OPMA-N, IOPMA-N showed more than 3 times apparent activity and more than 4 times catalytic efficiency(k_cat/K_m) at 50 ℃, pH=6.0—7.0, and had a significantly better tolerance to the pH from neutral to weakly acidic under moderate temperatures(30—50 ℃). IOPMA-N also exhibited a better operational stability and storage stability by its more than 75% of the apparent activity after 15 times repeated use and 31 d half-life when stored at 4 ℃, while OPMA-N would lose its activity completely after stored 5 d at 4 ℃. Comparative analysis of the catalytic product showed that IOPMA-N exhibited higher hydrolytic activity but slightly lower transglycosyl activity than OPMA-N, which is consistent with the fact that there is a functional(active) balance between hydrolytic and transglycosyl activities in OPMA-N molecule, and meanwhile, it also indicated that its substrate had a significant protective effect on its hydrolytic activity but hardly on its transglycosyl activity in its immobilization.



Synthesis of L/W Composite Zeolite and Its Application in FCC Gasoline Hydro-upgrading Catalyst^†

YANG Xu, DUAN Aijun, ZHAO Zhen, JIANG Guiyuan, LIU Jian, WEI Yuechang, LI Jianmei

2015, 36(2):  336-343.  doi:10.7503/cjcu20140761

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A novel L/W composite zeolite was synthesized via the in situ overgrowth of L zeolite on W zeolite and the corresponding physical-chemical property was characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM), Fourier transformed infrared(FTIR) spectrometry, N₂ adsorption, infrared spectroscopy of adsorbed pyridine, Raman and H₂-TPR. The results were compared with those of the mechanical mixture composed of the individual L zeolite and W zeolite. In the mechanical mixture, the L zeolite phase was morphologically separated from the W zeolite phase, while the L/W composite zeolite existed in a form of a epitaxial growth structure, with the W zeolite phase as the core and the L zeolite phase as the shell. Compared with the mechanical mixture, the composite had more appropriate pore structure and moderate aci-dity distribution, which could accelerate the diffusion of reactants and enhance the synergetic effect between Brönsted and Lewis acids. The comparison of the catalytic performances of the mechanical mixture and the composite-based Co-Mo catalysts for fluid catalytic cracking(FCC) gasoline hydro-upgrading showed that, due to the above advantages of the composite, the corresponding catalyst exhibited a lower octane number(RON) loss(ΔRON=-1.15) and higher desulfurization efficiency(HDS=93.3%).



Effect of Carbon Sources on the Performance of Methane-producing Biocathodes^†

XU Heng, WANG Cuiping, WANG Kaijun

2015, 36(2):  344-348.  doi:10.7503/cjcu20140727

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Effects of organic carbon source(OCS) and inorganic carbon source(ICS) on the performance of methane-producing biocathodes were studied. The current density, methanation, polarization curves and biomass attached were investigated during both start-up and stable operating periods. The results show that OCS not only accelerated formation of the methane-producing biocathode, but improved its operating performance. As for the polarization tests, the current density of the OCS-associated biocathode could reach (2.34±0.15) A/m² with the cathode potential poised at -0.75 V(vs. SHE), higher than that of the ICS-associated bioca-thode. Compared to ICS addition, OCS addition could achieve in-situ supply of carbon dioxide(CO₂), which would alleviate gas-liquid transfer limitations and promote microorganisms’ growth. In this case, the biomass attached on OCS-associated biocathode was more than 4 times as much as that on ICS-associated biocathode, further elucidating the high-performance of OCS-associated methane-producing biocathodes.



Fabrication and Performance of Organic Optoelectronic Devices with Alkali Metal Salts as a Cathode Interlayer^†

SUN Shuheng, WU Ying, ZHOU Weilong, CHEN Youchun, LI Fenghong

2015, 36(2):  349-354.  doi:10.7503/cjcu20140662

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Highly efficient organic small molecular light-emitting diodes(SMOLEDs), polymer light-emitting diodes(PLEDs) and polymer solar cells(PSCs) were fabricated using alkali metal salts(LiF, NaF, CsF and Cs₂CO₃) as a cathode interlayer. In SMOLEDs and PLEDs, introducing CsF as a cathode interlayer gives rise to the highest luminous efficiency and power efficiency in the four alkali metal salts. It is apparent that effect of LiF, NaF, CsF and Cs₂CO₃ as a cathode interlayer on device performance is different and modification ability sequence of the four alkali metal salts is CsF>Cs₂CO₃>NaF>LiF. When LiF is selected as a cathode interlayer in PSCs with poly(3-hexylthiophene)(P3HT)∶phenyl-C61-butyric acid methyl ester(P\begin{array}{c}{C_6}_0\end{array}BM) as an active layer, power conversion efficiency(PCE) can reach 4.12% while PCE values of PSCs with NaF, Cs₂CO₃ and CsF as a cathode interlayer are 3.72%, 3.55% and 3.2%, respectively. We further found that the alkali metals atoms which decomposed from the alkali metal salts and diffused into organic layer may influence the efficiency and current density of the SMOLEDs, PLEDs and PSCs.



Preparation and Visible-light Photocatalytic Activity of Cr-TiO₂ Microspheres with Reactive (001) Facet^†

YUAN Xia, GAO Bifen, WAN Jianfeng, LIN Bizhou, CHEN Yilin

2015, 36(2):  355-360.  doi:10.7503/cjcu20140599

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Cr-doped TiO₂(Cr-TiO₂) microspheres with a high percentage of exposed (001) facet were prepared by a one-step hydrothermal treatment. The morphology, crystal structure and photo-absorption property of the obtained samples were characterized by field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS), etc. The results demonstrated that Cr³⁺ ion and CrO₃ cluster coexisted in the catalysts. Cr³⁺ was incorporated into the crystal lattice of anatase TiO₂, which resulted in the Cr³⁺→Ti⁴⁺ charge transfer so that Cr-TiO₂ had strong absorption in the visible region. The corrosive effect of generated HF was weakened by doping small amount of Cr, which benefited for the formation of smooth exposed (001) facets in the Cr-TiO₂ samples. The visible-light-driven photocatalytic properties of the samples were studied by the degradation of Acid Red 88 dye. The Cr-TiO₂ microsphere with high exposure of (001) facet exhibited much higher efficiency than the traditional Cr-TiO₂ without exposed (001) facet. Such doped TiO₂ catalysts with definite surface micro-structure will be helpful for preparing TiO₂-based photocatalysts suitable for practical applications.



Synthesis of TiO₂/Ag₂NCN Composite Catalysts and Their Photocatalytic Activity Under Visible Light Irradiation^†

LI Xia, ZHANG Xia, ZHU Zefeng, LIN Guoqing, LI Youbin, LI Xiaoxue, XU Junli

2015, 36(2):  361-367.  doi:10.7503/cjcu20140532

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TiO₂/Ag₂NCN composite catalysts were fabricated through the precipitation of silver salt and cya-namide in the presence of TiO₂ nanoparticles. X-ray diffraction(XRD), scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR) and Ultraviolet-visible(UV-Vis) spectoscopy were used to characterize the composites. The results showed that the heterojunction structure was obtained by depositing TiO₂ nanoparticles on the surface of Ag₂NCN through weak physical interaction. The UV-Vis absorption peak of TiO₂/Ag₂NCN shift toward long wavelength and the energy gap narrow down in comparison with that of pure Ag₂NCN. The degradation of methylene blue(MB) catalyzed by the samples under visible-light irradiation was investigated and enhanced photocatalytic activity was observed for TiO₂/Ag₂NCN composite particles. The energy band structure of composite particles demonstrates that the presence of TiO₂ promote the separation of photogenerated electron and hole, and as a result, improves the photocatalytic activity.



Preparation and Properties of the High Capacity Si@PVP-GCB Core-shell Composite Anode Material Used in Li-ion Batteries^†

WANG Cunguo, PAN Xuan, ZHANG Lei, ZHU Mengkang, LI Dekai, DIAO Lingbo, LI Weiyan

2015, 36(2):  368-374.  doi:10.7503/cjcu20140482

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Si/C composite electrode material, Si@PVP-GCB[GCB=graphitized carbon black, PVP=poly(N-vinyl-2-pyrrolidone] was prepared at room temperature by one step-assembly technique. The samples were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetric analysis(TG) and Raman spectroscopy. It is found that a well-connected three dimensional(3D) nanoporous GCB network uniformly embedded with core-shell nanoparticles of the silicon nanoparticles(SiNPs) core and the PVP shell was formed. The GCB 3D network not only contributes to the high electrical conductivity of Si@PVP-GCB, but also strengthens the mechanical properties of the electrode material. Apart from that, the special hollow structure of GCB nanoparticles and PVP coating shell can buffer the volume variation of SiNPs much more effectively. The electrochemical results show that the Si@PVP-GCB delivered a reversible capacity of 545 mA·h/g at the current density of 50 mA/g after 100 cycles, much higher than that of the commercial graphite microspheres(GMs, 372 mA·h/g).



Synthesis, Thermal Decomposition Mechanism and Kinetic Equation of Polyhedral Boron Hydride Compound [(C₂H₅)₄N]₂B₁₀H₁₀ with High Enthalpy of Combustion^†

XUE Yunna, LI Jiaoyi, HAO Zhijun, WAN Hong, ZHAO Haixia, Li Chunying, DU Yongmei, Lu Juyou, Yu Qinwei, Lü Jian

2015, 36(2):  375-380.  doi:10.7503/cjcu20140473

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As a promising burning rate modifier of propellents, the boron hydride salt [(C₂H₅)₄N]₂B₁₀H₁₀ was synthesized by the pyrolysis of tetraethylammonium borohydride and characterized by IR, ¹H NMR, ¹¹B NMR and elementary analysis. The thermal stabilities in Ar or in O₂ were investigated by DSC and TG. The results showed that it decomposed with less heat release in Ar. But in O₂, it decomposed at first then was oxided with more heat release. The kinetic equation of thermal decomposition reaction was obtained by Kissinger method and Coat-Redfern program. Using combined solid reaction cell in-situ and FTIR, DSC-TG-FTRI-MS simultaneous techniques, thermal decomposition mechanism was supposed, the compound decomposes at 303.2 ℃, and produces C₂H₆, NH₃, H₂ and B.



Raman Spectroscopic Study on High Pressure-induced Phase Transition of D,L-Mandelic^†

WANG Kai, WANG Qinglei, YAN Tingting, LIN Aolei

2015, 36(2):  381-385.  doi:10.7503/cjcu20140417

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In situ Raman spectra of D,L-mandelic acid were characterized under high pressure generated by diamond anvil cell at room temperature. The pressure was up to 2.2 GPa. Around 0.6 GPa, some original Raman peaks disappear or split, and some new Raman peaks emerge. Within the experimental pressure range, the curve of Raman frequence-pressure presented inflexions at 0.6 GPa, indicating a phase transition from Pbca to P2₁/c for D,L-mandelic acid has occurred at this pressure. On total release of pressure, the Raman spectra returns to its initial state, implying this transition is reversible.



Polymer Chemistry

Hydration Structure of Partially Hydrolyzed Preformed Particle Gel^†

MA Ying, ZHANG Heng, YUAN Shiling

2015, 36(2):  386-394.  doi:10.7503/cjcu20140908

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Partially hydrolyzed preformed particle gel(PPG) was widely used in petroleum industry for enhancing oil recovery. Its aggregation and swelling in solution can effectively block the high permeability areas. In this work, a series of molecular dynamics simulations was conducted to investigate the swelling and hydration of PPG. After a 20 ns simulation, the volume and radius of gyration of the particle increased rapidly. The one reason was speculated as the strong hydration of hydrophilic groups of PPG(i.e. —COO^- and —CONH₂) in solution. It was shown that the structure of water was strongly modified by the presence of polymer. Then this polymer hydrophilic group induced modification was characterized from dynamic, structure and hydrogen bond aspects to gain a fully understanding of the hydration of PPG on molecular level. The structure of the hydration shell was investigated by spatial distribution function(SDF), radial distribution function(RDF) and distribution of dipole. The RDF and dipole distribution both indicated that O(COO^-) induced a more ordered and densely packed hydration shell than O(CONH₂) and N(CONH₂), which means that O(COO^-) has a very strong hydration ability. The dynamics of water around hydrophilic groups, as manifested in the translational and rotational diffusion and residence time of water is slowed down in the presence of the hydrophilic group. The electrostatic interaction and hydrogen bonds between water and hydrophilic group were speculated to account for their slow mobility. The hydrogen bonds in the vicinity of hydrophilic side groups also become stronger and longer lived by calculating the hydrogen bond residence time. The hydrogen bond network formed by hydration layer water molecules also stabilized the hydration shell according to the dipole reorientation residence time. In brief, the negatively charged center atoms of hydrophilic groups of PPG induced a highly ordered, tightly packed hydration shell around them and bound them with hydrogen bonds and electrostatic attraction which strengthened its hydration ability.



Interaction of Anionic Polyacrylamide with Cationic Surfactants^†

CAO Xulong, HU Yue, SONG Xinwang, ZHU Yangwen, HAN Yugui, WANG Kunpeng, GUO Dongsheng, LIU Yu

2015, 36(2):  395-398.  doi:10.7503/cjcu20140823

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It is noteworthy that the hydrophobically associating acrylamide copolymer is a new class of water-soluble polymers, derived from polyacrylamide by introducing a relatively low amount of hydrophobic groups(generally less than 5%, molar fraction) in polymer hydrophilic macromolecule chains. Because of special pro-perties of temperature resistance, salt tolerance, resistance to shear and storage stability, the material has been widely used in industry. The water-soluble negatively charged polyacrylamide was prepared by free radical copolymerization method. The interaction between cationic surfactants and polyacrylamide was researched in aqueous solution and NaCl solution including solubility, viscosity and rheological properties.