Table of Content

10 March 2016, Volume 37 Issue 3

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Cover and Content of Chemical Journal of Chinese Universities Vol.37 No.3(2016)

2016, 37(3):  0-0. 

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Review

Advance in Metal-based Nanoparticles for the Enhanced Performance of Organic Optoelectronics Devices^†

WU Xiaoyan, LIU Linlin, XIE Zengqi, MA Yuguang

2016, 37(3):  409-425.  doi:10.7503/cjcu20150916

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Metal nanoparticles(NPs) have made great contributions to the optical and electrical properties in the field of materials science, primary to the interest in their unique small size effect, quantum effect, surface effect and macro quantum tunnel effect. Recently, utilizing the unique optical and electrical properties of metal NPs enable them to be extensive applied in organic optoelectronic devices for further enhancing device performances, has becoming the research focus area. Until now, the best enhancement ratio of efficiency in organic light-emitting diodes and organic photovoltaics are 150% and 70%, respectively, especially the successful applications in the high-performance optoelectronic devices. The enhancement mechanism could be concluded to metal enhanced fluorescence, plasma enhanced absorption, energy transfer, electrical effect, scattering effect and so on. Here we review the different enhancement mechanisms introduced by surface plasma resonance and electrical effect of metal NPs, present the different strategies of incorporating different NPs and summarize the research works of metal NPs-based enhancing the performance of organic optoelectronic devices. The local surface plasma resonance of NPs also exist some problems when applied in devices, such as the limitation of action range, the enhanced wavelength region should matching with plasma resonance and so on. The researchers proposed some new design views such as “far-field” effect, the adjusting between NPs and excitons profile, scattering effect. With the comprehensive understanding of the mechanisms, further improvement in device performance and emerging applications can be expected for the new class of NPs-incorporated organic optoelectronic devices.



Letter

Synthesis of Lignin Based Epoxy Acrylate and Its UV-curing Research^†

YANG Dalei, ZHANG Niaona, HU Qiuxue, WEI Yingcong, YAN Ru, ZHANG Mingyao, ZHANG Huixuan, HU Wei

2016, 37(3):  426-428.  doi:10.7503/cjcu20150951

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Lignin was used as a monomer to synthesize the lignin based epoxy acrylates prepolymer(LBEA) with epoxy and acrylic acid. The obtained LBEA was UV cured into membrane to explore its application as paintings. The reaction process was studied by the epoxy index and acid number depending on the lignin ratio. Infrared spectroscopy(IR) proved that the LBEA was synthesized successfully. The performance of LBEA membrane, such as hardness, flexibility and acid and base resistance was characterized, and was better than that of epoxy acrylate.



Articles: Inorganic Chemistry

Surface Coating of Hydrophobic Up-converting Nanoparticles in Homogenous Liquid Phase System and Application in Optical Detection^†

ZHANG Qingbin, KONG Xianggui, CHENG Cheng

2016, 37(3):  429-434.  doi:10.7503/cjcu20150944

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NaYF₄∶Yb³⁺,Er³⁺ nanoparticles were successfully surface-coated via a hydrophobic nanoparticles adsorption surfactant intermediate(NaYF₄-SDS)process with hydrolysed poly(maleic anhydride-alt-1-octadecene) molecules(PMAO). This method overcomes the defect that oil-soluble nanocrystals and weak polar polymer molecules could hardly well-disperse in a single system and the surface-coating was realized in homo-genous solution system. The surface-coating process was confirmed by Fourier transform infrared spectra(FTIR) and surface Zeta potential. Investigations by transmission electron microscopy(TEM) and photoluminescence(PL) spectroscopy showed no obvious variations in the morphologies and luminescent properties of the nanoparticles during the surface-coating process. The specific molecular recognition capacity of PMAO-coated nanoparticles confirms that hydrophilic NaYF₄-PMAO are suitable for potential biological labeling.



Hydrothermal Synthesis and Characterization of Sb₂Te₃ Nanoplates^†

CHAI Zhenzhen, ZHENG Wenjun

2016, 37(3):  435-441.  doi:10.7503/cjcu20150808

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Under hydrothermal conditions and with ethanolamine acting as the reducing agent, fractional reduction of Te\begin{array}{c}{O}_3^{2-}\end{array} was realized, and Sb₂Te₃ nanoplates were synthesized in situ with the newly generated Te nanorods acting as tellurium source. The as-prepared product was characterized by X-ray powder diffractometer(XRD), field emission scanning electron microscope(SEM), and transmission electron microscope(TEM). Results showed that the product presents the hexastyle nanoplate structure with the thickness of about 100—200 nm and the diameter of about 0.6—1.5 μm, and has a uniform morphology and good dispersibility. The suitable conditions were that the volume ratio of water to ethanolamine was 8∶12, and the reaction lasted for 24 h at 180 ℃. By comparing the crystal structures of the elemental Te and hexagonal Sb₂Te₃ as well as some experimental results, that the hexagonal phase Sb₂Te₃ grew epitaxially on the lateral sides of newly generated Te nanorods was discussed preliminarily, and their crystal orientations were (003)Te//(003)Sb₂Te₃, and [110]Te//[110]Sb₂Te₃.



Analytical Chemistry

Electrodeposition of Platinum Nanoparticles on MgAl-layered Double Hydroxide Modified Indium Tin Oxide Electrode for Electrochemical Glucose Biosensor^†

XU Liang, LIN Youqin, CHEN Xu, LU Yanluo, YANG Wensheng

2016, 37(3):  442-447.  doi:10.7503/cjcu20150881

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MgAl-layered double hydroxide(MgAl-LDH) nanoparticles were synthesized by separate nucleation and aging steps. The MgAl-LDH nanoparticles were then immobilized on the surface of clean indium tin oxide(ITO) electrode. Electrodeposition of platinum nanoparticles(PtNPs) on the MgAl-LDH modified ITO electrode was carried out by electrochemical reduction of PtC\begin{array}{c}{l}_6^{2-}\end{array}. The obtained PtNPs/MgAl-LDH modified ITO electrodes exhibited high electrocatalysis activity for H₂O₂. After the glucose oxidase(GOD) was further immobilized on the above modified electrode, such prepared electrode was employed as the enzyme electrode for glucose detection. The results showed that the GOD/PtNPs/MgAl-LDH modified ITO electrodes had obviously enhanced the response sensitivity of the glucose biosensor and lowered the detection limit when detecting the H₂O₂ liberated in the enzymatic reaction between GOD and glucose.



Colorimetric Detection of Tin(Ⅱ) Ions Based on Layered Molybdenum Disulfide Nanosheets^†

HU Jie, WANG Yong, NI Yongnian

2016, 37(3):  448-453.  doi:10.7503/cjcu20150793

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In acetate/sodium acetate buffer(pH=4.5), tin(Ⅱ) ion displayed strong inhibitory effect on the color reaction of o-phenylendiamine(OPD) oxidized by hydrogen peroxide(H₂O₂) in the presence of layered molybdenum disulfide(MoS₂) nanosheets-based catalysts. This phenomenon was exploited to develop a colorimetric sensor for detection of tin(Ⅱ) ions. The experimental results showed that compared with the OPD/H₂O₂ colorimetric sensory system without MoS₂ nanosheets, MoS₂/OPD/H₂O₂ colorimetric sensory system exhibited increased sensitivity, low detection limit, and wide linear range toward tin(Ⅱ) ions. Under the optimum experimental conditions, the tin(Ⅱ) sensor based on MoS₂/OPD/H₂O₂ system provided a linear range of 0.02—3.0 μmol/L with a low detection limit of 8 nmol/L(S/N=3). Moreover, the MoS₂/OPD/H₂O₂ system displayed a high selectivity for tin(Ⅱ) detection, and can be used for the detection of tin(Ⅱ) ions in lake water samples.



Ionic Liquid Surfactant-mediated Ultrasonic-assisted Extraction Coupled with HPLC for the Determination of Five Rare Ginsenosides in Panax notoginseng (Burk.) F. H. Chen^†

LI Lanjie, LI Xuwen, DING Jian, LIU Ying, WU Qian, WANG Xiaozhong, LI Min, JIN Yongri

2016, 37(3):  454-459.  doi:10.7503/cjcu20150703

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A method of ultrasonic-assisted ionic liquid-salt aqueous two-phase extraction coupled with high-performance liquid chromatography(HPLC) was developed for the determination of the contents of five rare ginsenosides[20(S)-Rg₂, 20(S)-Rh₁, Rk₃, 20(S)-Rg₃ and Rk₁] in Panax notoginseng(Burk.) F.H.Chen(Sanqi). The factors influencing the ultrasonic-assisted extraction were investigated in detail. Under the optimized conditions, satisfactory extraction efficiency was achieved with the recoveries ranging from 92.07% to 110.55%, and the RSDs were lower than 5.43%. The results showed that the method had the advantages of fast, efficient, accurate and environmental protection. It provided a strong basis for the extraction, enrichment and analysis of the trace bio-active chemical composition of the traditional Chinese medicine and its preparations.



Gas Sensor Based on Porous Film of Polyaniline/sulfonated Nickel Phthalocyanine Composites for the Detection of Ammonia^†

ZHOU Xucheng, LI Zhihua, ZOU Xiaobo, SHI Jiyong, HUANG Xiaowei, HU Xuetao

2016, 37(3):  460-467.  doi:10.7503/cjcu20150669

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By utilizing the significant catalytic effect of sulfonated nickel phthalocyanine(NiTSPc) on the anilinepolymerization, a porous thin film of polyaniline(PANI) and sulfonated nickel phthalocyanine(PANI/NiTSPc) composite was deposited across the gaps of an interdigitated Au electrode(IAE) by a simple electrochemical polymerization method. The PANI/NiTSPc porous thin film was characterized by means of scanning electron microscopy(SEM), atomic force microscopy(AFM), energy dispersive spectrum(EDS) and Raman spectrum. At room temperature, the ammonia sensing properties of the PANI/NiTSPc porous thin film prepared at optimum conditions were studied. The sensitivity of the film to 76 mg/m³ NH₃ was up to 2.75 with response time as short as 10 s. In addition, rather fast recovery rate, good reproducibility and long-term stability were also observed in a wide concentration range from 3.8 to 1900 mg/m³. Therefore, the proposed PANI/NiTSPc nanocomposite thin film sensors are highly potential candidates in the field of NH₃ detection and electronic nose application in further work.



Microwave-assisted Fabrication of Nickel Hydroxide-Graphene Nanostructures and Their Application in Electrochemical Detection of Glucose^†

HU Yaojuan, HUANG Mengdan, CHEN Changyun, ZHANG Changli

2016, 37(3):  468-474.  doi:10.7503/cjcu20150593

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The nickel hydroxide-graphene[Ni(OH)₂-graphene] nanostructures were fabricated by facile microwave method, and the structure and electrocatalytic activities of the synthesized nanostructures were characterized via scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), X-ray powder diffraction(XRD), energy-dispersive spectroscopy(EDS), electrochemical impedance spectroscopy(EIS) and cyclic voltammetry. The results indicated that the Ni(OH)₂-graphene nanotructures exhibited a higher electrocatalytic activity than the Ni(OH)₂ nanoparticles. A glucose nonenzyme sensor was developed based on the Ni(OH)₂-graphene nanotructures. The sensor exhibited a low detection limit of 2 μmol/L, a wide linear range from 0.01 to 7.5 mmol/L, and a high sensitivity of 174.7 μA·cm^-2·mmol·L^-1. In addition, the sensor exhibited excellent stability and selectivity for the glucose detection, and it could be used to analyze real samples.



Organic Chemistry

Synthesis and Properties of Symmetric Azobenzene Derivative^†

YAN Chao, XIAO Yulong, DAI Heng, CHENG Xiaohong

2016, 37(3):  475-479.  doi:10.7503/cjcu20150839

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A new symmetric azobenzene compound(A) with triple alkoxy chain in each terminal was synthesized via Cu(Ⅰ)-catalyzed amino coupling reaction as the key step. The structure of this compound was identified with ¹H NMR, ¹³C NMR and elemental analysis. The property of compound A was investigated by UV-Vis spectroscopy and scanning electron microscopy(SEM). The results showed that compound A can form organolgels with different organic solvents, and the sol-gel transition could be observed under UV and visible light irradiation. The SEM images of xerogels of compound A showed the formation of three-dimensional networks composed of entangled fibrous aggregates. The gels were heating-, light- and mechan- responsive. The UV-Vis spectroscopy confirmed the photoresponsible behavior of compound A.



Anion Recognition of Indole-3-Aldehyde-o-Nitrophenylsemicarbazone^†

LIN Hai, LI Yawei, LIN Huakuan

2016, 37(3):  480-485.  doi:10.7503/cjcu20150835

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A novel anion recognition receptor with inner hydrogen band, indole-3-aldehyde-o-nitrophenylse-micarbazone, was designed and synthesized via indole-3-aldehyde and o-nitrophenylsemicarbazide. The receptor was characterized by ¹H NMR, ESI-MS and elemental analysis. The anion recognition properties of this receptor with AcO^-, F^-, H₂P\begin{array}{c}{O}_4^{-}\end{array}, Cl^-, Br^-, I^-, HS\begin{array}{c}{O}_4^{-}\end{array} were investigated with fluorescence and ¹H NMR spectrometry, respectively. The association constants and association ratio of the receptor with AcO^-, F^-, H₂P\begin{array}{c}{O}_4^{-}\end{array}, Cl^-, Br^-, I^-, HS\begin{array}{c}{O}_4^{-}\end{array} are 6.98, 1∶2; 6.85, 1∶2; 5.40, 1∶2; 13.51, 1∶2; 6.34, 1∶1; 5.40, 1∶1; 2.88, 1∶1, respectively. Because the receptor with inner hydrogen band has special structure and is well matching with Cl^- having appropriate bulk and basicity, the results of the fluorescence titration and ¹H NMR titration indicate the receptor has very strong bind capability and very high selectivity for Cl^-.



Synthesis and Biological Activity of Novel Dicyano-containning Cyclopropane-1-carboxamides^†

XU Gaofei, LIU Yanhong, YANG Xinling, WANG Daoquan, YUAN Dekai

2016, 37(3):  486-492.  doi:10.7503/cjcu20150729

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A series of novel dicyano-contained cyclopropanecarboxamide derivatives were designed and synthesized using fungicides containing cyano or cyclopropyl as leading structures. Intermediates 2-amino-2-(substituted) phenylacetonitriles or propionitriles 1a—1n were prepared via Strecker reaction. 1-Cyano-cyclopro-pyl-1-carboxylic(3) was obtained from ethyl cyanacetate and 1,2-dibrimoethane via cyclization and hydrolysis. 14 title compounds were obtained via the condensation of intermediates 1 and 3. The structures of all title compounds were confirmed by ¹H NMR and HRMS. Compound 4f showed good fungicidal activity against Pythium aphanidermatum and Pyricularia oryzae with inhibiton rates of 55.3% and 67.1% at 50 μg/mL in vitro and against Pseudoperonospora cubensis and Erysiphe graminis with inhibiton rates of 50% and 85% at 400 μg/mL in vivo. Compound 4m could give total control against Puccinia sorghi at 400 μg/mL in vivo. In addition, compounds 4c, 4d, 4g, 4j and 4m showed good larvicidal activity against mosquitoes(Culex pipiens pallens) at 5 μg/mL with the lethal rate above 60%; compounds 4h and 4j possessed larvicidal activity against armyworms(Mythimna separata) at 600 μg/mL with the lethal rate of 66.7% and 50%.



Synthesis of Three Stereoisomers of 4-(3-Hydroxylbutoxy)-2-butanol^†

SUN Baohou, ZHAO Yi, HAI Li, GUO Li, WU Yong

2016, 37(3):  493-497.  doi:10.7503/cjcu20150702

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Dihydroxydibutylether(DHBE) is a choleretic drug used for the treatment of gallstone and hepatic disorders due to its choleretic activity and hepatoprotective action. 4-(3-Hydroxylbutoxy)-2-butanol(1) is one of the three stereoisomers of DHBE. The compound has rapid efficacy in the body. It contains three stereoisomers, (R)-4-[(R)-3-hydroxybutoxy]-2-butanol(1a), (S)-4-[(S)-3-hydroxybutoxy]-2-butanol(1b) and (R)-4-[(S)-3-hydroxybutoxy]-2-butanol(1c). In this paper, the synthesis of the three stereoisomers of compound 1 from readily available starting materials, methyl (R/S)-3-hydroxybutanoate, in 5 steps with overall yields of 44%—50% was reported. The ether was synthesized by Williamson reaction first, followed by the removal of the benzyl. Then the target compounds 1a—1c were obtained. The synthetic approach has the advantages of easy manipulation, high yield and purity.



Microwave-assisted One-pot Conversion of Salicylaldehydeoximes to 2-(Difluoromethoxy)benzonitriles^†

WANG Tao, HUA Mingqing, LIU Weihan, HUANG Yan, ZHANG Qi

2016, 37(3):  498-504.  doi:10.7503/cjcu20150670

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Eight 2-(difluoromethoxy)benzonitrile derivatives including seven novel compounds were synthesized in moderate yields by one-pot multistep reaction of salicylaldehydeoximes using sodium 2-chloro-2,2-di-fluoroacetate(SCDA) as difluoromethylating reagent and potassium carbonate as base under microwave-assisted condition. The structures of all novel compounds were confirmed by nuclear magnetic resonance spectrum(¹H NMR, ¹³C NMR, ¹⁹F NMR), infrared spectrum(IR) and high resolution mass spectrum(HRMS). The effects of difluorocarbene reagent, alkali, solvent, microwave power, reaction temperature and time on the reaction were considered. The optimized reaction conditions: salicylaldehydeoximes(2 mmol), 2-chloro-2,2-difluoroacetate(3 mmol), K₂CO₃(3 mmol) and N,N-dimethylformamide(2 mL), microwave power 300 W, reaction temperature 85 ℃, reaction time 20 min. A possible mechanism was proposed on the basis of the experiments and contrast tests.



Physical Chemistry

Molecular Dynamics Studies on the Selective Deposition of 3(5)-(9-Anthryl) Pyrazole onto Self-assembled Monolayers^†

ZHANG Luge, XUE Zexu, ZHANG Chong, YAN Hui

2016, 37(3):  505-512.  doi:10.7503/cjcu20150781

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The site-selective deposition behavior of 3(5)-(9-anthryl) pyrazole(ANP) onto self-assembled monolayers(SAMs) patterned substrate was studied via the equilibrium and steered molecular dynamics methods. Two kinds of different densely packed SAMs were constructed on silicon oxide substrates as the patterned templates, which represent liquid expanded(LE) and liquid condensed(LC) phases. Equilibrium molecular dynamics(MD) simulations showed that the packing density of alkyl chains on the substrate could influence the deposition behavior of the ANP molecules. On the LE covered SAM, the small molecule would submerge deeply into the alkyl chains film, while ANP molecule would deposit on the surface of LC film. Steered molecular dynamics showed that ANP molecule was hindered from the densely packed LC film. However, there was less hindrance for ANP to submerge into the LE film. Using umbrella sampling and the weighted histogram analysis method, the potential of mean force(PMF) of the deposition process of ANP onto the two patterned templates was calculated. From the PMF curves, the favorite deposition location of ANP onto the two SAMs was determined, which agreed well with that obtained from equilibrium MD simulations. The binding energies between ANP and the two SAMs can be estimated based on PMF, which could be used to explain the site-selective deposition of ANP on different densely packed SAMs.



Theoretical Studies on the Reaction Mechanism of Criegee Intermediates CH₃CHOO with OH Radicals^†

GAO Zhifang, WANG Weina, MA Qian, LIU Fengyi, WANG Wenliang

2016, 37(3):  513-520.  doi:10.7503/cjcu20150742

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The reaction mechanism of CH₃CHOO with OH was studied at the CCSD(T)//B3LYP/6-311+G(d,p) level. The results show that the detailed mechanism mainly includes hydrogen abstraction, addition-decomposition and oxidation reactions. The calculations show that β-H abstraction reaction is favoured in the syn-CH₃CHOO reaction with OH with a apparent activation energy(E_app) of -4.88 kJ/mol, whereas the addition-decomposition channel is advantaged in the reaction of anti-CH₃CHOO with OH in combination with a E_app of -13.25 kJ/mol. The barriers of anti-CH₃CHOO are lower than that of the syn-CH₃CHOO in addition-decomposition and oxidation reactions, while the syn-CH₃CHOO is lower than anti-CH₃CHOO in the β-H abstraction pathway. The rate constant of addition-decomposition in the reaction of anti-CH₃CHOO satisfies a strong negative temperature dependent, while oxidation channels of syn-/anti-CH₃CHOO obey a positive temperature effect. The temperature dependent of three kind of reactions are different, which makes their relative rate can be controlled by adjusting the temperature.



Preparation of Zn_0.11Sn_0.12Cd_0.84S_1.12/g-C₃N₄ Heterojunctions and Their Photocatalytic Performance Under Visible Light^†

ZHANG Qian, HU Shaozheng, LI Fayun, FAN Zhiping, WANG Qiong, WANG Fei, LI Wei, LIU Daosheng

2016, 37(3):  521-528.  doi:10.7503/cjcu20150721

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Visible light responsive ZnSnCdS/g-C₃N₄ heterojunction photocatalysts were synthesized via a simple hydrothermal treatment. X-ray diffraction(XRD), scanning electron microscopy(SEM), UV-Vis spectroscopy, Fourier transform infrared spectroscopy(FTIR), inductively coupled plasma-mass spectrometry(ICP-MS), photoluminescence(PL) spectroscopy, and X-ray photoelectron spectroscopy(XPS) were used to characterize the prepared catalysts. The results indicated that the heterojunctions were formed by the formation of C—S bond across the g-C₃N₄/ZnSnCdS interface, which facilitates interfacial charge transfer and improves the separation efficiency of electron-hole pairs. The activities of catalysts were tested in photocatalytic rhodamine B(RhB) degradation under visible light. The results indicated that the ZnSnCdS/g-C₃N₄ heterojunction photocatalysts show obvious higher photocatalytic activity than the single g-C₃N₄ or ZnSnCdS. With the optimal g-C₃N₄ mass fraction of 20%, the as-prepared heterojunction photocatalyst displays the highest RhB degradation rate, which is 32.3 and 4.9 times that of single g-C₃N₄ and ZnSnCdS, respectively. Not only ZnSnCdS but other ternary metal sulfides, ZnMoCdS, MoNiCdS and NiSnCdS, can combine with g-C₃N₄ to form the heterojunction catalyst to promote the separation rate of electrons-holes.



Theoretical Studies on Performance of Transiton Metal-substituted Keggin-type Phosphotungstate Dyes for Dye-sensitized Solar Cells^†

SUN Linlin, ZHANG Ting, YAN Likai, SU Zhongmin

2016, 37(3):  529-533.  doi:10.7503/cjcu20150710

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A series of Keggin type phosphotungstate with different transition metal-substituted dyes was designed. The electronic properties, UV-Vis absorption spectra and performance parameters of transition metal-substituted Keggin-type phosphotungstate dyes were systematically investigated via density functional theory(DFT) and time-dependent DFT(TD-DFT) methods. The results reveal that the absorption spectra of systems [PW₁₁O₃₉MCH₂COOH]^n- [M=Ru^Ⅱ(2), Ir^Ⅲ(3), Os^Ⅱ(4), Co^Ⅲ(5)] are red-shifted compared to the experimental system [PW₁₁O₃₉RhCH₂COOH]^5-(1). Especially, the spectra of system 4(M=Os^Ⅱ) has wide and strong absorption in visible region. And it has high electron injection efficiency and light harvesting efficiency, which may have important application in dye-sensitized solar cells(DSSCs) field.



MH⁺(M=Fe, Co, Ni)-catalyzed Hydrogenation of Carbon Dioxide^†

ZHANG Yingnan, LI Jilai, HUANG Xuri

2016, 37(3):  534-538.  doi:10.7503/cjcu20150680

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Density functional theory(DFT) method at B3LYP level was conducted on the reaction of MH⁺(M=Fe, Co, Ni)-catalyzed hydrogenation of carbon dioxide. The results show that hydrogen transfer to C is much easier than to O. The effect of DFT methods was also explored. FeH⁺ has higher reactivity than CoH⁺ and NiH⁺ on hydrogen transfer to C according to the coupled cluster theory CCSD(T) calculations. Electronic structure analysis demonstrates hydrogen transfer reaction process is hydride transfer.



Asymmetric Hydrosilation of Aromatic Ketones Catalyzed by CuFe₂O₄ Nanoparticles^†

ZHU Jielian, XIA Xiaofeng, LIANG Minting, LIU Xiang, LI Hexing

2016, 37(3):  539-545.  doi:10.7503/cjcu20150650

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CuFe₂O₄ nanoparticles were synthesized by coprecipitation, sol-gel and solvothermal methods, respectively. The asymmetric hydrosilation of aromatic ketones was catalyzed by CuFe₂O₄ nanoparticles, employing (R)-BINAP[2,2'-bis(diphenylphosphino)-1,1'-binaphthalene] as chiral ligand and polymethylhydrosiloxane as hydrosilating reagent. The results showed that compared to the others, the CuFe₂O₄ nanoparticles prepared by solvothermal method had spherical shape, small size, better dispersion, uniform distribution and excellent catalytic activities. Meanwhile, it was found that the catalytic activity of the CuFe₂O₄ nanoparticles was significantly improved with the addition of t-BuOK and t-BuOH. An efficient heterogeneous catalytic system CuFe₂O₄/t-BuOK/t-BuOH was finally obtained. Under room temperature and air atmosphere, the conversion of the aromatic ketones and the enantiomeric excesses of the (R)-1-arylethanols were up to 99% and 92%, respectively, with the heterogeneous catalytic system. It was also confirmed that the electronic effect and steric hindrance of the groups on the aromatic ring distinctly affected the results of hydrosilation. And a possible mechanism was presented to explain the influence of some key factors on the reaction. Furthermore, it was demonstrated that the CuFe₂O₄ nanocatalyst could be easily separated from reaction system under an external magnetic field. And after recycling for four times, the catalyst could also have a high catalytic activity for the asymmetric hydrosilation.



Ion-transfer Reaction of SO₄^2- Across the Water/1,2-dichloroethane Interface Modified by an Anion Exchange Membrane

WANG Huanhuan, HU Daopan, JIANG Xuheng, ZHANG Yehua, CHEN Yong

2016, 37(3):  546-551.  doi:10.7503/cjcu20150626

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In this work, the anion-transfer reaction of highly hydrophilic sulfate across the water/1,2-dichloroethane(W/DCE) interface modified by a homogeneous anion exchange membrane(AEM) was investigated by employing cyclic voltammetry(CV), differential pulse voltammetry(DPV) and chronocoulometry. It was found that the electrochemical window could be extended by the modification of W/DCE interface with such an AEM. In addition, the well-defined CV and DPV curves corresponding to the ion-transfer of highly hydrophilic SO₄^2- could be obtained at the modified W/DCE interface. According to the linear relationship between the peak current of CV and the square root of scan rate, as well as the equation of Randles-Sevik, the diffusion coefficient of SO₄^2- in the membrane containing water is calculated to be about 7.6×10^-8 cm²/s. In addition, the peak current of DPV increases linearly with the concentration of SO₄^2-within the range of 5-25 mmol/L. Moreover, the standard reaction rate constant of the ion-transfer of SO₄^2- at such an AEM-modified W/DCE interface was estimated to be about 1.49×10^-3 cm/s via chronocoulometry.



High Efficency Synthesis of Ferrocenyl Derivatives Catalyzed by Trace Amount Cyclopalladated Complex^†

SUO Quanling, ZHANG Danzhao, KE Chunlong, ZHU Ning, GAO Yuanyuan, XIE Ruijun, HAN Limin

2016, 37(3):  552-558.  doi:10.7503/cjcu20150624

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A series of ferrocenyl derivatives with special substituent(1—9) in middle to excellent yields was synthesized by Suzuki-Miyaura cross-coupling reaction using new diferrocenylimine cyclopalladated complex(Fc₂C=NPh)PdClPPh₃(Fc=Ferrocenyl, Ph=Phenyl) as catalyst and Fc-I as reactant. The cross-coupling reaction conditions were optimized and the substrate scope was investigated, and a synthetic route was given for preparing ferrocenyl derivatives and the catalytic reaction mechanism was deduced. The results show that the complex catalyst highlights the features of high catalytic activity, trace catalyst loading, wide substrate scope, excellent reaction efficiency and insensitive to air and moisture for synthesizing ferrocenyl derivatives.



Molecular Dynamics Simulation on CL-20/TNT Cocrystal Explosive^†

LIU Qiang, XIAO Jijun, ZHANG Jiang, ZHAO Feng, HE Zhenghua, XIAO Heming

2016, 37(3):  559-566.  doi:10.7503/cjcu20150605

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Molecular dynamics(MD) simulation was conducted for 2,4,6,8,10,12-hexanitrohexaazaiso-wurtzitane(ε-CL-20) and 2,4,6-trinitrotoluene(TNT) crystal, CL-20/TNT cocrystal with equal molar ratio and CL-20/TNT composite with equal molar ratio using COMPASS force field with isothermal-isobaric(NPT) ensembles at different temperatures. Their structures, interactions between different components and mechanical properties were investigated. The cohesive energy density(CED) of the cocrystal decreases with rising temperature, and is greater than that of the composite. The binding energy(E_bind) between two components of the cocrystal also decreases gradually with rising temperature, and is twice times as strong as that of the CL-20/TNT composite. In addition, pair correlation function analysis and enlarged local structure show that hydrogen bonds exist between the two components in the cocrystal and these bonds are mainly formed between H atoms in TNT and O atoms in CL-20, and H atoms in CL-20 and O atoms in TNT. The values of the tensile, bulk and shear modulus(E, K, G) for CL-20/TNT cocrystal fall in between those for ε-CL-20 and TNT crystals and decrease with increasing temperature, which agrees with general expectation. However, the Cauchy pressure(C₁₂-C₄₄), K/G and Poisson’s ratio(ν) for CL-20/TNT cocrystal are much larger than those for the two crystals, which predicts the cocrystal has much higher ductility and elastic elongation.



Fabrication of HCPT-Layered Double Hydroxide Nanohybrids via Co-assembly Method and Its Characterization

PANG Xiujiang, LIU Yuan, CHEN Li, QUAN Zhenlan

2016, 37(3):  567-572.  doi:10.7503/cjcu20150589

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Hydroxyl camptothecin-layered double hydroxides(HCPT-LDH) nanohybrids were prepared by co-assembling between HCPT and Zn₂Al-NO₃ LDH nanosheets prepared using microchannel reactor, which indicated the obtained nanosheets could be used to fabricate LDH based drug delivery and controlled release system. After being treated with acetic acid, inactive carboxylate form HCPT transformed into bioactive lactone form HCPT. It is important for preparing high bioactive HCPT-LDH nanohybrids. The co-assembly method showed various remarkable advantages, such as simple procedure, short reation time, mild condition, high drug loading and good dispersity. Additionally, drug loading can be easily controlled by adjusting raw material ratios. HCPT molecules arrays aslant in double layers along longitudinal axis in the gallery of LDH. The nanohybrids showed well controlled release property and in vitro drug release kinetics from the nanohybrids could be fitted with the pseudo-second-order kinetic model. The diffusion of HCPT through the LDH particles played an important role in the control of the drug release.



Preparation of Fe₃O₄@IRMOF-3/Pd and its catalytic performances as a Heterogeneous Multifunctional Catalyst

ZHANG Yanmei, ZHANG Jing, LI Xiaofang, CHU Gang, TIAN Miaomiao, QUN Chunshan

2016, 37(3):  573-580.  doi:10.7503/cjcu20150511

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Pd nanoparticles supported on Fe₃O₄@IRMOF-3 fabricated by a step-wise assembly method was prepared and evaluated as a potential heterogeneous catalyst for Knoevenagel condensations, Suzuki-coupling and hydrogenations. The results demonstrated that the magnetic multifuctional material was active and stable as a heterogeneous catalyst for the reactions mentioned above. Remarkabaly, It was an effective and size selective catalyst for alkenes. Furthermore, it could be magnetically recovered and reused for at least 9 times without obvious loss of activity.



Polymer Chemistry

Mesophase Formation and Structure Evolution of Poly(lactic acid) During Annealing

ZHANG Yanyan, ZHUO Ranran, LI Guili, SHAO Chunguang, LI Qian, XU Xianzhong, WANG Yaming, CAO Wei, LIU Chuntai, SHEN Changyu

2016, 37(3):  581-586.  doi:10.7503/cjcu20150788

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Poly(lactic acid)(PLA) film were prepared by quenching, and the structure evolution of amorphous PLA film was researched online by in situ Fourier transform infrared spectrophotometer(FTIR) analysis based on different annealing temperatures. The results showed that there was a critical crystallization temperature. The cold crystallization of sample could be realized through partial adjustment of the molecular chain when the annealing temperature was above the critical value, conversely, none of cold crystallization could happen. Besides, it was found that mesophase always first appeared in the cold crystallization process, followed by a mesophase-to-crystal phase transformation, while the transition from amorphous to mesophase took place through the synchronous adjustment of the molecular intrachain conformation and interchain packing. The higher the annealing temperature increased, the earlier the mesophase emerged, and the resulting crystal structure would become more and more regular.



Brownian Dynamics Simulations on Single Chain Conformation of Graft Polyampholytes in Good Solvents

PU Binbin, CHEN Tao, WANG Liquan, ZHU Shasha

2016, 37(3):  587-594.  doi:10.7503/cjcu20150708

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Ascribed to the coexistence of opposite charges on same chain, polyampholytes present novel conformational behavior. By means of Brownian dynamics simulations, the conformations of moderately grafted polyampholytes(GPA), whose backbone and branches are oppositely charged in equilibrium, were investigated in salt-free good solvents. The influences of backbone length, side chain number and charge density were analyzed. The results revealed that with enhancing the electrostatic interactions, conformational transition process of GPA was composed of four stages including coil, overlapping between backbone and side chains, segment collapsing and charge pairing. Differ from linear polyampholytes, the strength of additional steric and electrostatic repulsions between side chains in GPA varies with changing the molecular structure and affects the conformational transition. Due to solvation of good solvents, a re-extension of GPA chains occurs under strong electrostatic interactions to ensure the completion of quadrupoles paired by dipoles. Decreasing the backbone length or the charge fraction, or increasing the side chain number strengthens the repulsions and rigidifies the backbone, resulting in retardation of molecular collapse and intensification of chain re-extension.



Decay of Free Radicals in Polycarbosilane Induced by γ-Rays Irradiation

CHENG Yong, LI Xiaohu, LIU Weihua, WU Guozhong, WANG Mouhua

2016, 37(3):  595-599.  doi:10.7503/cjcu20150705

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The formation and decay behavior of the free radicals trapped in polycarbosilane(PCS) induced by γ-rays irradiation in N₂ were investigated by electron spin resonance(ESR). ESR analysis showed that the trapped radicals induced by γ-rays irradiation were assigned to Si radicals(≡Si·). The concentration of free radicals increased with absorbed dose linearly at the lower dose, and the G value of the radical formation was calculated to be 9. However, the concentration of free radicals tends to be saturated when the absorbed dose reached 200 kGy. Upon storage in N₂ at ambient temperature the free radicals decayed slowly with a half-life of 23 d. On the contrary, the free radicals decayed rapidly after the sample was exposed to air due to their oxidation, the half-life was only 8 h. The rate of radical decay was accelerated by annealing at elevated temperature, the free radicals trapped in PCS could be removed thoroughly after heating up to 250℃ in N₂.



Physical Chemistry

Preparation of Multi-functional Wound Dressing with Core-shell Nanofibers via Co-axial Electrospinning

CHEN Lamei, CAO Jie, YE Lin, ZHANG Aiying, FENG Zengguo

2016, 37(3):  600-606.  doi:10.7503/cjcu20150671

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The uncrosslinked wound dressing with core-shell nanofibers was firstly fabricated via co-axial electrospinning. The nanofiber was composed of the polycaprolactone(PCL) core loaded with anti-bacterium drug mupirocin and collagen shell with anesthesia lidocains. The surface morphology of uncrosslinked dressing and its core-shell structured fibers were characterized by scanning electronic microscopy and transmission electronic microscopy, respectively. The crosslinked wound dressing can be further prepared by the crosslinking of collagen shell, and the successful crosslinking can be proved by the enhanced tensile strength and swelling ratio. In vitro drug release tests implied two dressings both possessed the burst release stage and sustainable release stage for two loaded drugs, which confirmed the sustainable acesodyne and anti-bacteria effects for both dressings. The bicinchonininc acid(BCA) test results showed that the collagen in uncrosslinked dressing could also be sustainably released, while in vitro cell attachment test depicted that uncrosslinked dressing could promote the cell attachment and growth better than crosslinked dressing. Furthermore, the in vitro anti-bacteria test showed that both dressings loaded with mupirocin had significantly better anti-bacteria ability than those without mupirocin indicating their excellent anti-bacteria ability. Two as-prepared multifunctional wound dressings possessed acesodyne and anti-bacteria effects and were able to promote the healing process so that they can reduce the pains of patients, reduce the number of dressing change, and enhance treatment effect.