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10 November 2014, Volume 35 Issue 11

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Cover and Content of Chemical Journal of Chinese Universities Vol.35 No.11(2014)

2014, 35(11):  0-0. 

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Articles: Inorganic Chemistry

Hydrothermal Syntheses and Characterizations of Vanadium Phosphates with Extra-large 16-Ring Channels^†

LI Li, YAN Yan, WANG Daming, ZHENG Dafang, LI Jiyang

2014, 35(11):  2285-2290.  doi:10.7503/cjcu20140725

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Using n-butylamine, n-propylamine and piperidine as templates or structure directing agents(SDAs), three new open-framework vanadium phosphates VPO-n(n=1, 2, 3) were hydrothermally synthesized. These compounds were characterized by single-crystal and powder X-ray diffractions, ICP, elementary analysis, TGA, SEM and XPS analyses. VPO-1 crystallizes in the cubic system, space group Im3m, with a=b=c=2.6586(3) nm, α=β=γ=90°, V=18.791(4) nm³. The structure of VPO-1 has 3D intersecting 8-ring and extra-large 16-ring channels, as well as large cavities with 32-ring windows. VPO-n(n=1, 2, 3) are iso-structures, which are analogous to [HN(CH₂CH₂)₃NH]K_1.35[V₅O₉(PO₄)₂]·H₂O synthesized by triethylenediamine(DABCO) as template. Structure comparison of these compounds indicates that the organic templates not only influence the symmetry and cell parameters of the crystal structure, but also can control the opening sizes and shapes of the channels and the cages in the resulting structures.



Synthesis of Polyoxometalate Microtubes with Hierarchical Structure and the Adsorption of Doxorubicin^†

WEI Yi, PENG Jun, YU Xia, DING Yanhong, LU Haiyang, REN Zixing, XU Min, LI Guangzhe

2014, 35(11):  2291-2296.  doi:10.7503/cjcu20140563

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Saturated Keggin-type SiW₁₂ microtubes have been synthesized from the trivacant SiW₉ by a simple template-free method. The microtubes were characterized by Fourier transform infrared(FTIR) spectroscopy, powder X-ray diffraction(PXRD) and thermogravimetric analysis(TGA). The hierarchical structure was exa-mined by optical micrograph and field emission enviromental scanning electron microscope(ESEM). To apply the hierarchical structure, doxorubicin(DOX) was adsorbed in the as-prepared SiW₁₂ microtubes, and DOX-loaded microtubes were obtained, which showed red luminescence of doxorubicin under violet light excitation.



pH Response of Inverse Opal Photonic Crystal Gel^†

WANG Qiuhong, XUE Min, WANG Fengyan, YAN Zequn, XUE Fei, CHEN Wei, QI Fenglian, MENG Zihui, XU Zhibin

2014, 35(11):  2297-2302.  doi:10.7503/cjcu20140456

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In this paper, we focus in the pH response of inverse opal photonic crystal gel. First, a series of monodispersed submicrometer silicon particles was prepared by Stöber method. Then, these particles were self-assembled into three dimensional(3D) ordered colloidal crystal film in vivid color using vertical deposition method. Sequentially, methacrylic acid(MAA) and ethylene glycol dimethacrylate(EGDMA) were copolymerized in the interspace of the silica 3D photonic crystal template. After the silica particles were etched by HF, 3D inverse opal photonic crystal hydrogels with highly ordered interconnected pores were obtained. The resultant inverse opal hydrogel shifted the reflection from 514 nm to 590 nm as pH value increased from 5 to 8. The structural color changed from blue-green to red within an equilibrium time of less than 2 min.



Preparation and Luminescence Properties of Self-assembly Based CdTe Hyper-branched Nanostructure^†

DUAN Bin, WANG Zhiwei, PAN Gencai, PAN Lingyun

2014, 35(11):  2303-2309.  doi:10.7503/cjcu20140630

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We propose a simple and efficient method to build three-dimensional nanostructure. Driven by the strong dipole interaction, CdTe quantum dots can form the hyper-branched nanostructures with layer-by-layer self-assembly process. The HRTEM images show that the prepared hyper-branched nanostructures are polycrystal structures and composed by the original CdTe quantum dots. Thus the quantum confinement effect of original quantum dots is inherited by formed nanostructures. Experimental results indicate that the configurations of nanostructures can be influenced by the curing time, pH value of solution and proportion of precipitation agent. The luminescence experiment shows that the formed hyper-branched nanostructure well keep the linear optical properties of original quantum dots, therefore these nanostructures own the great potential to be used in the field of photovoltaic conversion, sensor and so on.



Solvothermal Preparation and Growth Mechanism of CuInS₂ Thin Films of Nanosheet Array

ZHUANG Mixue, WEI Aixiang, LIU Jun, YAN Zhiqiang, ZHAO Yu

2014, 35(11):  2310-2316.  doi:10.7503/cjcu20140235

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CuInS₂(CIS) thin films of nanosheet array were deposited directly onto transparent conductive fluorine-doped tin oxide(FTO) substrates by solvothermal method using the precursors of copper(Ⅱ) chloride dihydrate, indium(Ⅲ) nitrate, thiourea, hexadecyl trimethyl ammonium bromide, oxalic acid, and ethanol. The morphology, crystallographic structure, chemical composition, and optical property of CIS thin films of nanosheet array were investigated using scanning electron microscopy(SEM), high resolution transmission electron microscopy(HRTEM), X-ray diffraction(XRD), Raman spectrum, energy dispersive spectrometry(EDS) and UV-Vis spectroscopy, respectively. It is revealed that highly uniform and dense vertical arrays of single crystalline nanosheets with chalcopyrite planes are formed. The atomic ratio of Cu/In/S is 1.1:1:2.09, very close to theoretical value of 1:1:2 of stoichiometric CIS. CIS thin films of nanosheet array have good light absorption characteristics at the UV-visible and near infrared wave range, and the optical band gap is found to be 1.51 eV. The growth mechanism of CIS thin films of nanosheet array was investigated according to the characterization of CIS thin films deposited at different reaction times.



Analytical Chemistry

Conversion Rule of Rare Ginsenosides Produced from Major Ginsenosides by Confined Microiwave Promoted Degradation Method^†

YAO Hua, JIN Yongri, YANG Jie, LI Lanjie, SUN Ting, SHI Xiaolei, LI Xuwen

2014, 35(11):  2317-2323.  doi:10.7503/cjcu20140641

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In order to prepare the rare ginsenosides which were considered to have higher bioactivities, confined microwave method to promote the degradation of 7 kinds of major ginsenosides(Rb₁, Rb₂, Rb₃, Rc, Rd, Re, Rg₁) to rare ginsenosides were adopted. Comparing with the degradation products of non-microwave method at the same condition, the rules of conversion about the structures and ingredients of degradation products were concluded by HPLC analysis. The results indicated that confined microwave method can completely degrade all the major ginsenosides, while nearly no major ginsenosides can be degraded under the same condition of non-microwave method. Protopanaxadiol-type ginsenosides were easily deglycosylated at C20, where the conformational changes would take place. It would generate 20(S)-Rg₃ and 20(R)-Rg₃ among which the R-type was the superior configuration. Dehydration effect of the hydroxyl at C20 made 20(S/R)-Rg₃ convert to Rk₁ and Rg₅, meanwhile the losing of glucose of 20(S/R)-Rg₃ at C3 position made the generation of 20(S/R)-Rh₂. After further dehydration at C20 position, 20(S/R)-Rh₂ converted to Rk₂ and Rh₃. Moreover, the configurations of glycosyls at C20 of ginsenosides would affect the proportion and composition of rare ginse-nosides in degradation products, but Rg₅ reached highest content in all confined microwave degradation products of 7 kinds of protopanaxadiol-type ginsenosides. Protopanaxatriol-type ginsenosides had similar rules with protopanaxadiol-type ginsenosides by the confined microwave degradation method, and the products of Re and Rg₁ were determined in the highest content of Rh₄.



Organic Chemistry

Spectral Properties and Antitumor Activity of 10-Hydroxycamptothecin and Its Application in Cell Labeling^†

DING Guobin, LI Binchun, GUO Yi, XU Li

2014, 35(11):  2324-2328.  doi:10.7503/cjcu20140575

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The spectral properties of 10-hydroxycamptothecin(HCPT) were investigated by UV-Vis spectrophotometer, fluorescence spectrophotometer and fourier transform infrared spectroscopy. The antiproliferative activities of HCPT against three tumor cell lines, human cervical can-cer cell line(HeLa), human breast cancer cell line(MCF-7) and human fibrosarcoma cell line(HT1080), were determined using an MTT assay, and the IC₅₀ values of HCPT to the three tumor cell lines were 16.37, 16.73 and 19.24 μg/mL, respectively. The growth inhibitory effect of HCPT on a normal cell line, HEK293T(human embryonic kidney cells 293T), was also investigated, the highest inhibitory rate reached 88.72% at an HCPT concentration of 40 μg/mL, indicating that the normal cell line HEK293T is more sensitive to HCPT in comparison to the three tumor cell lines. Using HeLa cell line as a model, Annexin V-FITC apoptosis detection kit was employed to demonstrate the antitumor mechanism of HCPT. Almost all the cells were simultaneously stained by Annexin V-FITC and PI, the cell membrane was green while the nucleus was red, which indicated that HCPT induced the late apoptosis process of HeLa cells. The distribution of HCPT in HeLa cells was observed by fluorescence microscopy, which provides scientific basis for its application in cell labeling.



Mechanism of Lentinan Hydrolysis Based on ESI-CID-MS/MS and Preparation of Full Series of Oligosaccharides^†

ZHANG Hongtao, ZHU Li, ZHANG Shuang, ZHAN Xiaobei

2014, 35(11):  2329-2334.  doi:10.7503/cjcu20140492

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To acquire the mechanism of lentinan hydrolysis and full series of gluco-oligosaccharides from hydrolyzed lentinan, the hydrolysis time of lentinan treated with 0.02 mol/L trifluoroacetic acid(TFA) at 100 ℃ was optimized through analysis the distribution of different degree of polymerization(DP) oligosaccharides at 2, 4, and 6 h. And then lentinan hydrolysis was repeated another three times until no precipitation can be observed under optimal hydrolysis time. The mass spectrometry character of 7-mer oligosaccharides from all the four batch hydrolysis products was analyzed using ESI-CID-MS/MS based on the mass spectrometry character of 7-mer β-1,3-and β-1,6-gluco-oligosaccharides, and acquiring a hydrolysis mechanism. Finally, all the four batch hydrolysis products were combined and separated with P4 column and full series of gluco-oligosacchaides from 2-mer to 13-mer were acquired. The optimal time for lentinan hydrolysis was 4 h, and β-1,3/1,6-gluco-oligosaccharides in hydrolysis lentinan was observed at the first batch, and then the amount of β-1,3/1,6-gluco-oligosaccharides reduced with the increasing of hydrolysis times, and there only observed β-1,3-gluco-oligosaccharides at the fourth hydrolysis products. This results also suggested that the triple helix structure zone containing β-1,3/1,6-linkage of lentinan is loose, but the only containing β-1,3-linkage triple helix structure zone in lentinan is tight. The theory acquired in this work will supply useful information for preparation gluco-oligosaccharides in large-scale and it also expand the gluco-oligosaccharides library for exploring protein-carbohydrate interaction using carbohydrate microarray.



Hydrogenation of Acetophenone Promoted by Ruthenium Complexes of Modified Glucosamine Derivatives^†

LIU Xiaojing, ZHOU Hongyong, LIU Bing, LI Xiaona, SONG Shasha, LI Yunqing, WANG Jiaxi

2014, 35(11):  2335-2340.  doi:10.7503/cjcu20140267

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The glucosamine acetal derivative L1 and sulfonamide derivatives L2—L4 were synthesized via the reaction of hydroxy and/or amine of glucosamine. The catalytic properties of the catalysts generated in situ from the reaction of Ru(Ⅱ) compounds with glucosamine based ligands were evaluated in the hydrogenation of acetophenone with i-PrOH as hydrogen source. The catalytic activity was enhanced by the introduction of organic group into the glucosamine frame. The effects of reaction temperature, time, molar ratio of acetophenone to catalyst and base on the catalytic reaction of the hydrogenation of acetophenone promoted by the combination of RuCl₂(PPh₃)₃/L4 were explored. The turn over frequency(TOF) was up to 1232 h^-1 at 413 K with n(catalyst):n(KOH):n(acetophenone)=1:10:5000. Among the bases used, the potassium isopropoxide was the best one to activate the precatalyst. The kinetic results revealed that the reaction was the first order respect to acetophenone, and the apparent activition energy was 37.13 kJ/mol. The catalyst system of RuCl₂(PPh₃)₃/L4 was stable in the hydrogenation of acetophenone. The plausible reaction mechanism was proposed.



Synthesis of η⁶-[Tris(trimethylsilyl)phenylsilane]tricarbonylchromium Complexes and Theoretical Studies on the Possible Interaction of Intermolecular Si—Si Bonds and Chromium Centers^†

LÜ Haoting, LIU Tingting, ZHANG Mingtao, LIU Jie, SUN Huailin

2014, 35(11):  2341-2345.  doi:10.7503/cjcu20140252

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Intramolecular Si—Si bond activation by transition metals has been widely found in transition metal complexes with polysilanyl substituted η⁴- and η⁵-ligands, but such activation in η⁶-phenyl complexes keeps unknown. In this study, η⁶-[tris(trimethylsilyl)phenylsilane]tricarbonyl chromium complexes, η⁶-[(SiMe₃)₃SiC₆H₄R]Cr(CO)₃(R=H, Me and MeO), were synthesized by reaction of tris(trimethylsilyl)phenylsilane, p-R(Me₃Si)₃SiC₆H₄ with hexacarbonylchromium in diethylene glycol dimethyl ether. The products were characterized by ¹H NMR, ¹³C NMR, IR spectra and elemental analyses. The molecular structure of η⁶-[(SiMe₃)₃SiC₆H₄R]Cr(CO)₃(R=H) was determined by the X-ray diffraction method. The possibility of the Si—Si bond activation by the intramolecular chromium center was examined experimentally. The results showed that the Si—Si bonds in the complexes were stable under thermal conditions. Density functional theory(DFT) calculation of possible Si—Si bond activation processes indicated that all the reaction interme-diates and transition states had such high energies that the Si—Si bonds were unable to be activated by the intramolecular chromium center. These results demonstrated that Si—Si bond activation should be difficult to take place in polysilanyl substituted η⁶-phenyl transition metal systems.



Synthesis and Application of Four Fluorescence Labeled Nucleotides Through Disulfide as Reversible Terminators in DNA Sequencing by Synthesis

TANG Daonian, JIANG Min, LI Xiaowei, KANG Yani, WU Xinyan, GONG Bing, SHAO Zhifeng, ZHAO Xiaodong, SHEN Yumei

2014, 35(11):  2346-2352.  doi:10.7503/cjcu20140251

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DNA sequencing is one of the important means of biological research. The development of accurate and high-throughput DNA-sequencing methods has a strong impact on biomedical research. Sequencing by synthesis(SBS) approaches is one of the most important techniques of DNA sequencing. A series of SBS methods have been investigated and implemented. In SBS methods, the principal thing is to synthesize four fluorescently labelled cyclic reversible terminators as the sequencing reagents. These cyclic reversible terminators need to connect the fluorescein through a cleavable linker. In chemical biology, disulfide bridges, which are known to be efficiently and rapidly cleaved by mild reducing agents, have been used in a wide range of applications including drug delivery, functional and structural proteomics, DNA and tumor imaging. The disulfide-based cleavable linker is commonly used due to its rapid cleavage and straightforward synthesis. In this work, starting from 5-iodo-2'-deoxyuridine, 5-iodo-2'-deoxycyridine, 7-deazo-7-iodo-2'-deoxyadenosine and 7-deazo-7-iodo-2'-deoxyguanosine, four kinds of fluorescence labelled necleotides with four different bases through disulfide were synthesized and characterized. The synthesized fluorescence labelled nucleotides can be recognized and accepted by an identified DNA polymerase, incorporated faithfully into DNA strand, followed by cleaved completely by DTT within 1 min. These results demonstrate that the fluorescence labelled nucleotides have potential value as reversible terminators in DNA sequencing by synthesis.



Synthesis and Anti-hepatitis B Virus Activities of Heterocyclic Substituted Matijin-Su Derivatives^†

LIANG Guangping, HU Zhanxing, LIU Qingchuan, HUANG Zhengming, ZHANG Jianxin, LIANG Guangyi, XU Bixue

2014, 35(11):  2353-2359.  doi:10.7503/cjcu20140223

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N-(N-Benzoyl-L-phenylalanyl)-O-acetyl-L-phenylalanol was isolated from Dichondra repens Forst., which was a phenylalanine dipeptide compound with anti-HBV activity, named Matijin-Su(MTS). Its chemical skeleton structure was different from that of the existing drugs for anti-HBV. MTS was used as a lead compound base on the better anti-HBV activity by preliminary research. A series of MTS derivatives was designed and synthesized by a series of reactions, such as the formation of an amide(peptide), hydrolysis, condensation, acylation, alkylation and esterification using L-phenylalanine and its substitution as starting materials. The synthesized derivatives of MTS were characterized by ¹H NMR, ¹³C NMR, ESI MS and elemental analysis. Their anti-hepatitis B virus activities against HepG2 2.2.15 cells line in vitro were tested. From the screening results, compounds 5b(IC₅₀=8.20 μg/L, SI=10.26), 5g(IC₅₀=5.58 μg/L, SI=22.78) and 5i(IC₅₀=5.07 μg/L, SI=16.67) exhibited significant anti-HBV activities, the inhibition ratio were 56.57%, 67.06% and 66.83%, respectively.



Synthesis of Functionalized Enamines(Ⅳ): β,β-Dicyanostyrene Derivatives Reacted with NBS Converted into Corresponding Enamines Promoted by NaOAc^†

CHEN Zhanguo, LIU De’e, LI Wenli, LIU Yali

2014, 35(11):  2360-2363.  doi:10.7503/cjcu20140218

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An easy and efficient new method for the expeditious synthesis of functionalized enamines from β,β-dicyanostyrene derivatives reacted with N-bromosuccinimide(NBS) was developed. The β,β-dicyanostyrene derivatives were smoothly converted into corresponding functionalized enamines promoted by NaOAc(200%, molar fraction) in DMF at room temperature in good to excellent yield within 80 min. This new method has many advantages such as mild conditions, easy handling, nearly quantitative yields 12 substrates with different structures were investigated. The results indicated that the protocol has applicability in a large scope of the electron-deficient olefins. A possible addition-elimination pathway was proposed and it explained well the full regiospecificity of the reaction. The structures of all products were confirmed by their ¹H NMR, ¹³C NMR and HRMS analysis.



Synthesis of a Fluorescence Labeled Spin Trap and Its ESR Study^†

WANG Bing, DU Libo, LIU Yangping, ZHOU Jianwei, LIU Yang

2014, 35(11):  2366-2369.  doi:10.7503/cjcu20140201

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Free radicals play a key role in physiological and pathological processes including aging and cancer development. To understand the biological role of free radicals, it is of critical importance to develop highly sensitive techniques for the detection and quantitation of free radicals being produced. Among the numbers of techniques used for the detection of free radicals, electron spin resonance(ESR)-spin trapping technique, owing to its relative higher specificity, is believed to be an indispensable method for the detection of free radicals in biological systems. However, the ESR-spin trapping technique was limited becauseit has the relative low sensitivity and it’s hard to achieve real-time detection of free radicals in living cells. Considering that the fluorescence probes for labeling and tracking subcellular structures in living cells are easily available, a new spin trap conjugated with fluorescence moiety(DanPPN) was synthesized and characterized. The ESR study showed that the DanPPN could be used for the detection of superoxide anion, oxygen and carbon-centered radicals. Moreover, it was observed that the fluorescence intensity of DanPPN was decreased with the increase of the concentration of AIBN. The results suggested that the new spin trap may have a potential use for the detection of free radicals in biological systems.



Physical Chemistry

Theoretical Studies on the Taking off of Oxygen-containing Functional Groups in Lignite Model Compounds^†

TANG Haiyan, ZHAO Maoshuang, FENG Li, CAO Zexing

2014, 35(11):  2370-2376.  doi:10.7503/cjcu20140612

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The removal reaction mechanism of different kinds of oxygen-containing functional groups in lignite was investigated, benzoic and phenol were chosen as model compounds. Density function theory(DFT) and DFT-based B3LYP method along with mixed basis sets 6-311+G(d,p) were applied in all calculations. The results suggest that removal approaches are different from different kinds of oxygen-containing functional groups and the taking off energy is also different. According to the reaction activation energy of different kinds of reactions, autocatalysis reaction of structure unit containing carboxyl is the easiest. Taking account of the influence of water molecular to the reaction, formic acid and glycerin were studied as model compounds. The results show that water molecular can reduce the reaction activation energy and accelerate the reaction process, the best catalytic effect is achieved with one or two water molecular. The effects of Na⁺, K⁺ and their carboxylates to the reaction were studied on glycerin as well. The results suggest that Na⁺ and K⁺ can reduce the reaction activation energy by forming complexes with glycerin, which stabilizes the transition state structure. Na⁺ has a better catalytic effect to the reaction. Comparing with sheer ions, the catalytic effects of carboxylate can’t reach that good. However, potassium carboxylate’s catalytic effect doesn’t change a lot, while the catalytic effect of sodium carvoxylate has a significant decrease.



Theoretical Studies on the Structures and Second-order Nonlinear Optical Properties of 12-Vertex Fluorocarborane Molecules^†

FANG Xinyan, WANG Wenyong, WANG Jiao, LI Xiaoqian, SONG Hongjuan, QIU Yongqing

2014, 35(11):  2377-2383.  doi:10.7503/cjcu20140605

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The structures and second-order nonlinear optical(NLO) properties of tetrafluoro carborane and its derivatives were investigated with density functional theory method. The results indicate that elongating the conjugation or enhancing the strength of donor(D) and acceptor(A) groups affect the distances of the carborane cage. Generally speaking, the dipole moment of molecule is determined by the D/A strengths, that is, the stronger D/A groups the larger dipole moment. Meanwhile, the polarizability of each molecule increases with the increasing of the conjugation and volume of substituents. Introducing the substituents with strong electron-withdrawing abilities or promoting the conjugation of substituents can effectively improve the second-order NLO coefficients. Furthermore, from the analysis of electronic absorption spectrum and the corresponding molecular orbit compositions, charge transfer pattern that comes from the carborane cage to the acene substituent illustrates the first hyperpolarizability value of molecule 4a' is the largest.



High Pressure Raman Spectra of Silicone Oil^†

WANG Xiaoxia, LI Zhihui, CHEN Chen, WANG Kai, HAN Bo, ZHOU Qiang, LI Fangfei

2014, 35(11):  2384-2389.  doi:10.7503/cjcu20140541

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The Raman spectra of silicone oil with different viscosities(Silicone oil AP 150 wacker, Baysilone oil M1000 and Baysilone oil M30000) as a function of pressure up to 20 GPa were investigated in a diamond anvil cell. The pressure dependence of Raman vibrations of these silicone oils were obtained and analyzed. The results indicated that the molecular structure or configuration of Baysilone oil M1000 changes at 0.47 GPa and that of Baysilone oil M30000 changes at 0.31 GPa, respectively. This is confirmed by the decrease of the intensity of the Si—O stretch vibration and the emerging of novel vibrations at the corresponding solidification point. In addition, it was found that the pressure dependence of the vibrational frequencies changes and some vibrational modes disappear at 10, 8 and 4.5 GPa for Silicone oil AP 150 wacker, Baysilone oil M1000 and Baysilone oil M30000, respectively, indicating the inherent structural change of these silicone oils.



Investigation on Structures and Nonlinear Optical Properties of Super-short Carbon Nanotube Systems with Surface-adsorbing Lithium Atoms^†

LI Shaochen, YU Guangtao, CHEN Wei, HUANG Xuri

2014, 35(11):  2390-2396.  doi:10.7503/cjcu20140513

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Under the density functional theory(DFT) method, the structures and nonlinear optical(NLO) properties of seven new Li_n@cyclophenacene(n=1—3) species were investigated in detail, where one to three Li atoms are adsorbed over the surface of the super-short carbon nanotube([8]cyclophenacene). In these systems, the Li atoms can be adsorbed stably on the nanotube, as revealed by their considerable adsorption energies(84.0—106.2 kJ/mol). Besides, when adsorbing one to two alkali Li atoms, the first hyperpolarizability of the carbon nanotube can be effectively improved, where the β₀ value can be significantly increased from zero to the range of 3.42×10³—8.29×10³ a.u., owing to the occurrence of charge transfer process from the Li atom to the nanotube. Comparatively, when increasing the number of the adsorbed Li atoms to three, the β₀ value can be further enhanced sharply, even to as large as 2.59×10⁶ a.u., which can be attributed to the formation of the excess electron. Moreover, the distance between the adsorbed Li atoms can also play an important role in effecting the first hyperpolarizabilities of systems. This work can provide some new valuable insights for designing the new type of high-performance NLO materials based on the carbon nanotubes.



Reduction of Hexavalent Chromium over the Expanded Graphite Supported Palladium Nanocatalyst^†

WEI Yingxiang, TU Weixia

2014, 35(11):  2397-2402.  doi:10.7503/cjcu20140481

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Expanded graphite(EG) supported palladium nanocatalysts(Pd-EG) were synthesized by wet-impregnation reduction method with the aid of a polymer stabilizer. The catalysts were characterized by various techniques including X-ray diffraction(XRD), transmission electron microscope(TEM) and X-ray photoelectron spectroscopy(XPS). The catalytic activities of the synthesized Pd-EG nanocatalysts were evaluated for the reduction of Cr(Ⅵ). The results indicated that the Pd loading of Pd-EG nanocatalysts was 0.446%(mass fraction) in the form of Pd nanoparticles with an average diameter of 4.37 nm. The Pd-EG nanocatalysts show high catalytic activity in the complete reduction of Cr(Ⅵ) to Cr(Ⅲ) with a turn-over frequency(TOF) of 3186 h^-1 at pH=4.0 and 45 ℃. The Pd-EG catalysts exhibit efficient and stable catalytic performance even after several times of recycles.



Three-body Effect in Hydrogen-bonded Complexes Containing Amides and Uracil^†

LI Shushi, JIANG Xiaonan, WANG Changsheng

2014, 35(11):  2403-2409.  doi:10.7503/cjcu20140477

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Many-body effect plays a critical role on the structures and properties of clusters and condensed phases. Therefore the quantitative evaluation of the strength of many-body effects is important. In this paper, the three-body interactions and their contributions to the total interaction energy for hydrogen-bonded complexes composed of amide, dipeptide, uracil and water were evaluated at the second-order perturbation MP2 level of theory. It is found that the three-body interactions contribute as high as 10%—20% to the total interaction energy of the hydrogen-bonded complexes. It is also found that the three-body interaction is a short-range interaction, suggesting that the neighboring three-body effect should be taken into account in molecular simulation at least.



Preparation of Reduced Graphene Oxide-based Melamine Sponge and Its Absorption Properties^†

WANG Zitao, XIAO Changfa, ZHAO Jian, HU Xiao, XU Naiku

2014, 35(11):  2410-2417.  doi:10.7503/cjcu20140476

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Graphene oxide(GO) was synthesized via the Hummers method and ultrasonic stripping method using the natural graphite as raw materials. Furtherly, reduced graphene oxide-based melamine sponges(RGOME) were fabricated via a dip-coating method which were post-reduced online. As-prepared RGOME sponges were investigated by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR) and optical contact angle measuring apparatus. Oil adsorption capacity, the oil/water selective adsorption and reusability of the RGOME sponges were also studied. The results demonstrate that the RGOME sponges exhibit good hydrophobicity and superoleophilicity, and oil adsorption capacity is up to 56—127 g/g. The adsorptive process of oils, like toluene and kerosene, was fitted to the Bangham equation for the isothermal adsorption. In terms of selective adsorptive process, the concentration of oil in oil-water mixture decreased drastically, while oil adsorption capacity constantly increased. The resulting separation efficiency was up to 74.49%, and as-prepared sponges have better performance for oil/water separation than other sorbents reported in the literature. In addition, the RGOME sponges can be reused more than 10 times with gently deteriorating in adsorption capacity.



Catalytic Property of Titanyl Acetate in the Transesterification Reaction of Dimethyl Carbonate and Phenol^†

TANG Rongzhi, WANG Songlin, ZHANG Yuanzhuo, CHEN Tong, WANG Gongying

2014, 35(11):  2418-2424.  doi:10.7503/cjcu20140420

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Titanyl acetate was prepared through the solvothermal reaction between titanium(Ⅳ) n-butoxide, acetic anhydride and distilled water. Titanyl acetate was firstly used in the transesterification reaction of dimethyl carbonate and phenol to diphenyl carbonate and exhibited excellent performance. When titanyl acetate amount is 0.10 g, the phenol conversion reaches to 47.8% and transesterification selectivity is 99.9% with trace anisole. Based on the results of FTIR, solid state ¹³C NMR, titanyl acetate reacts firstly with phenol. The acetate group of titanyl acetate is replaced by phenoxy group and generates phenoxy titanium complex. It could be considered that phenoxy titanium complex is the real catalyst for the transesterification of dimethyl carbonate and phenol with good resuability.



Co-sputtering Sn-Al/Cu Composite Thin Films as Anode Materials of Li-ion Batteries^†

WEI Lin, WANG Lixiu, TAO Zhanliang, CHEN Jun

2014, 35(11):  2425-2430.  doi:10.7503/cjcu20140313

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Sn-Al/Cu composite thin films with planar and three dimensional(3D) network structures, which were prepared by co-sputtering method on copper foil or foam, were used as the anode materials of Li-ion batteries. The phase structure and surface morphology of Sn-Al composite thin films were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The electrochemical performance of Sn-Al composite thin films was evaluated with charge/discharge and electrochemical impedance spectroscopy(EIS) at room temperature. The results showed that Sn-Al composite thin films with 3D network structure displayed a capacity of 410 mA·h/g after 50 cycles at a current density of 600 mA/g, and a capacity of 464 mA·h/g at a current density of 2000 mA/g. The improved electrochemical performance such as cycling stability and columbic efficiency is attributed to the 3D network structure, which can obviously restrain the volume change of Sn-Al composite thin film during the insertion/extraction process of lithium ion. In addition, copper foam with large specific surface area and rough surface can promote the reaction with lithium sufficiently.



High Pressure-enhanced Dimeric Aggregation in Methylene Blue Solution^†

WANG Kai, QI Guangyu, JIANG Zhangmei, LIN Aolei

2014, 35(11):  2431-2434.  doi:10.7503/cjcu20140312

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The monomer-dimer equilibrium of methylene blue(MB) in two different solvents[deionized water and 4:1(volume ratio) methanol-ethanol] was studied by in situ high pressure UV-Vis absorption spectroscopy. Using diamond anvil cell, the highest pressure conducted in the experiments was about 0.8 GPa in water and 8.7 GPa in methanol-ethanol solvent. The absorbance ratio of monomer to dimer decreased with the increase of pressure, indicating that high pressure can promote dimerization of MB. On release of pressure, the intensity of the peak did not return to original state, but the absorbance ratio of monomer to dimer returned to the initial value, showing that the changes of the absorption spectra under high pressure are reversible.



Fabrication and Photocatalytic Activity of BiPO₄@Ag₃PO₄ Core/Shell Heterojunction^†

REN Yanlin, LI Xinyong, ZHAO Qidong

2014, 35(11):  2435-2441.  doi:10.7503/cjcu20140266

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BiPO₄@Ag₃PO₄ core/shell heterojuction photocatalyst was synthesized through a facile hydrothermal process followed by the ion-exchange method. The morphology, crystallinity, composition, and photophy-sical properties of the catalyst were systematically investigated by scanning electron microscope(SEM), X-ray diffraction(XRD), energy dispersive X-ray analysis, UV-Vis diffuse reflectance spectrophotometer(DRS) and X-ray photoelectron spectroscopy(XPS). Meanwhile, Rhodamine B(RhB) was chosen as the target pollutant to evaluate the photocatalytic activity of BiPO₄@Ag₃PO₄ photocatalyst under the visible light and simulated sunlight irradiation, respectively. The results show that RhB was almost totally degraded in 60 min under visible-light irradiation and in 40 min under sunlight irradiation, respectively. The BiPO₄@Ag₃PO₄ core/shell heterojunction photocatalyst displayed enhanced photocatalytic activity against RhB, which is attributed to the effective charge separation by the core/shell heterojuction between the Ag₃PO₄ and BiPO₄. Active species detection experiments proved that during the process of degradation of pollutants over the core/shell microrods, the main mechanism was the direct oxidation process by the photo-induced holes. Ag₃PO₄ shell can improve the absorption of the visible light effectively and also enhance the stability, dispersibility and photocatalytic activity of the photocatalyst. The BiPO₄@AgPO₄ photocatalysts show attractive potential applications in pollution control, water splitting and solar cell.



Supramolecular Self-assemblies of Cucurbit[7]uril with N,N'-Bis(4-dimethylaminobenzyl)-decane-1,10-diamine^†

YANG Bo, WU Mingqiang, XIAO Xin, XUE Saifeng, TAO Zhu, WEI Gang

2014, 35(11):  2442-2446.  doi:10.7503/cjcu20140255

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Molecular motions are quite common in biosystems and closely related to macroscopic motions guest. In the present work, N,N'-bis(4-dimethylaminobenzyl)-decane-1,10-diamine(C10DA) with multiple binding sites was designed and synthesized, while the structures and interaction of cucurbit[7]uril with the guest were investigated by ¹H NMR technique, electronic absorption and fluorescence spectroscopies in details. The experimental results showed that cucurbit[7]uril can include C10DA forming a pseudorotaxane inclusion complexes or dumbbell-shaped inclusion complexes by changing the molar ratio of the host and guest. This observation contributes to a deeper understanding in molecular recognition, design and construction of novel molecular machines.



Synthesis and Properties of Photoresponsive Organogels Based on Azobenzene Derivatives

FAN Dongli, ZHAI Yan, ZHANG Yan, TU Wei, HUANG Yaodong

2014, 35(11):  2447-2454.  doi:10.7503/cjcu20140195

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Eighteen azobenzene derivatives, 1a—6a, 1b—6b and 1c—6c, were synthesized and their gelation behaviors were tested. The synthesized azobenzenes readily formed stable gels in many polar or apolar organic solvents. As the representative, the structures of gels from compound 4b and the driving force of the gel formation were investigated by SEM and ¹H NMR. The photoresponse of the gels from compounds 4a—4c was studied and they all showed gel-sol transition under UV light irradiation while sol-gel transition in visible light radiation. Teas parameters of the solvents and gelators were systematically calculated and presented in the Teas plots. The results show that the four gelation behaviors(solution, partial gelation, gelation and precipitation) are located in different regions respectively. In the region of gelation, the distance between the solvent and the gelator reflects the thermal stability of the gel, the farther the distance is, the better the thermal stability of the gel will be.



Effect of Particle Size on the Electrocatalytic Activity of Pt/C Catalysts for Oxidation of Formic Acid^†

WANG Yanen, CAO Shuang, WU Weihong, WU Min, TANG Yawen, LU Tianhong

2014, 35(11):  2455-2459.  doi:10.7503/cjcu20140156

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In methanol solvent, using SnCl₂ as reducing agent, carbon supported Pt(Pt/C) catalysts with different size of Pt particles were prepared. X-ray diffraction(XRD) and transmission electron microscopy(TEM) measurements demonstrated that in the obtained Pt/C catalysts, the Pt particles have great uniformity and good dispersion. The electrochemical experiments indicated that the effect of average particle size of Pt/C catalysts for formic acid oxidation is obvious. The Pt/C catalyst with 3.2 nm average size of the Pt particles exhibited the optimal electrocatalytic performance for formic acid oxidation. This effect of particle size may be related to the quantity of the oxygen-containing species on the surface of the catalyst, the apparent surface area and the relative crystallinity of the platinum particles.



Preparation of Pt Hollow Nanoparticles Using Ag as the Template and Electrocatalytic Performance for Methanol Oxidation^†

XIONG Ting, LIN Jianyun, SHANG Zhongjin, ZHANG Xiantu, LIN Xuan, TIAN Wei, ZHONG Qiling, REN Bin

2014, 35(11):  2460-2465.  doi:10.7503/cjcu20140130

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Ag nanoparticles with two different particle sizes and uniform size-distribution were prepared at 18 ℃ by adjusting the adding amount of the NaOH solution, using silver nitrate as the precursor, polyvinylpyrrolidone(PVP) as the surfactant, ascorbic acid(AA) as the reductant. Pt hollow(Pt_hollow) nanospheres with different shell thicknesses and modified glassy carbon(GC) electrode(Pt_hollow/GC) were synthesized by adjusting the amount of precursor H₂PtCl₆·6H₂O at room temperature, using Ag colloids as the template. The morphology, composition and structure of Pt_hollow were characterized by scanning electron microscopy(SEM), high resolution transmission electron microscopy(HRTEM), energy-dispersive X-ray spectroscopy(EDS), X-ray diffraction(XRD) and other detection techniques; the electrocatalytic oxidation activity of Pt_hollow/GC, Pt solid nanoparticle modified GC(Pt_nano/GC) electrode were studied and compared using methanol as a probe molecule. The results show that the Pt_hollow nanospheres have a uniform particle size and good dispersity, and the electrocatalytic oxidation activity of Pt_hollow/GC for methanol is significantly higher than that of Pt_nano/GC electrode.



Preparation of FGO/PBMA Composites with Improved Thermal Stability^†

ZHANG Danfeng, FAN Louzhen, GUO Ruihua, FAN Zetan

2014, 35(11):  2466-2471.  doi:10.7503/cjcu20140120

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Graphene oxide(GO) nanosheets was modified by 3-triethoxysilylpropylamine(KH550) to get functional graphene oxide(FGO). Then FGO was reacted with butyl methacrylate(BMA) via in situ polymerization with the initiator AIBN in N₂. The prepared functional graphene oxide/polybutylmethacrylate(FGO/PBMA) composites were characterized by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectrometry(XPS), scanning electron microscope(SEM) and thermal gravimetric analysis(TGA). The thermal stability of the FGO/PBMA composites were significantly enhanced compared with that of neat PBMA. The maximum mass loss temperature increased from 267 ℃ for neat PBMA to 339 ℃ for FGO/PBMA composites. Meanwhile the reaction mechanism was also discussed.



Polymer Chemistry

Structure and Properties of Fe₃O₄/Polystyrene Nanocomposites^†

ZHANG Zhijie, TANG Tao

2014, 35(11):  2472-2480.  doi:10.7503/cjcu20140646

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Oleic acid modified Fe₃O₄ nanoparticles(OA-Fe₃O₄) with uniform particle size were blended with polystyrene(PS) by solution-mixing/evaporation drying method. The resultant PS/Fe₃O₄ nanocomposites exhibited superparamagnetic property. It was found that OA-Fe₃O₄ nanoparticles were well dispersed in PS matrix, when the content of OA-Fe₃O₄ was 1%—10%(mass fraction). Differential scanning calorimetry(DSC) analysis showed that the glass transition temperature(T_g) of PS nanocomposites decreased with the increase of the amount of Fe₃O₄ nanoparticles. According to the results from thermal gravimetric analysis(TGA), the presence of OA-Fe₃O₄ would significantly enhance the thermal stability of PS under air condition. Rheological analysis showed that the melt viscosity of PS nanocomposites decreased with the increase of the amount of nanoparticles(0—10%). Furthermore, we also found that the viscosity reduction took place in the PS with bimodal distribution after adding OA-Fe₃O₄, when the average molecular weight of PS was higher than critical entanglement molecular weight of PS and the radius of nanoparticles was smaller than PS’s mean-square radius of gyration.



Effect of the Alkyl Side Chain on the Helical Conformation of Dialkylpolysilane Copolymers^†

TANG Xianhui, JI Xingxing, QIAN Kai, LI Yi, YANG Yonggang

2014, 35(11):  2481-2486.  doi:10.7503/cjcu20140577

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Silane copolymers [P(Si1-co-Si2)] were synthesized using (S)-2-methylbutyl-n-decyldichlorosilane(Si1) and 2-ethylbutyl-n-decyldichlorosilane(Si2) monomers. A series of P(Si1-co-Si2) was synthesized by varying the ratio of Si1 and Si2. The random copolymer was confirmed by nuclear magnetic resonance. The chirality transfer behaviour of polysilane samples was characterized by circular dichroism spectrum(CD) and ultraviolet absorption spectrum(UV). It was found that homopolymer of achiral monomer Si2 exhibited no CD signal, but intense and sharp UV absorption at 324 nm. When the chiral monomer Si1 was added into the main chain of polymer molecules, the obtained copolymer molecules were induced with a marked CD signal. When the mole fraction of Si1 increased, the intensity of CD signal became higher rapidly, even as little as 2.0%(molar fraction) of enantiopure Si1 could induce a marked single-handed helical conformation in these copolymers. After that, the intensity of CD signal increased slightly and then decreased slightly. Moreover, the λ_max value tended to blueshift progressively with increasing the molar fraction of the chiral moiety in the copolymers. For P(Si1-co-Si2) of 50%Si1(P50) with diffierent molecular weight, the λ_max tended to redshift with increasing molecular weight, and the lower molecular weight P50 possessed a stronger optical activity. The result indicated that the handedness of the copolymers was controlled by the chiral alkyl chain and the odd-even effect of the achiral alkyl chain was not reflected.



Synthesis of Amorphous Polyaryletherketone Containing Phthalein and Fluorene as Side Groups^†

WANG Zhipeng, WANG Feifei, WANG Honghua, ZHOU Guangyuan

2014, 35(11):  2487-2493.  doi:10.7503/cjcu20140564

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A series of linear high molecular weight amorphous polyaryletherketone(PAEK) copolymers with phthalein and fluorene side groups was synthesized on the basis of the polyetherketone with phthalein cardo group(PEK-C). The structures were characterized by FTIR, ¹H NMR, ¹³C NMR. Gel permeation chromatography(GPC) data indicated that the \begin{array}{c}{\overline{M}}_n\end{array} and the \begin{array}{c}{\overline{M}}_w\end{array} of the copolymer were higher than 6.0×10⁴ and 1.0×10⁵, respectively, with a polydisperity index(PDI) ranging from 1.6 to 1.7. The X-ray diffraction(XRD) data revealed that the copolymers were amorphous structure. Thermogravimetric analysis(TGA) and differential scanning calorimetry(DSC) tests showed that the copolymers exhibited good heat resistant property. The onset temperature of mass loss was higher than 467 ℃. The char yield at 700 ℃ was more than 58.9%. There was a single glass transition temperature(T_g), with T_g>243 ℃. The elastic modulus and elongation at break of the copolymer showed a significant increase, up to 3.1 GPa and 58%, respectively, which were 1.4 folds and 8.3 folds compared to that of PEK-C when the feed ratio of phenolphthalein and 9,9-bis(4-hydroxyphenyl) fluorene was between 3:7 and 5:5. Amorphous polyaryletherketone containing phthalein and fluorene as side groups kept good solubility in chloroform, dichloromethane, tetrahydrofuran(THF), N-methyl-2-pyrrolidone(NMP) and other aprotic solvents. The mechanical and thermal properties were improved significantly.



Synthesis and Properties of Allyl-containing Trisphenol-based Benzoxazine^†

ZHU Chunli, BAI Haijian, GENG Pengfei, WEI Yanze, LU Zaijun

2014, 35(11):  2494-2498.  doi:10.7503/cjcu20140204

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1,3,5-Tri(3-allyl-3,4-dihydro-2H-1,3-benzoxa-zinyl)benzene(tp-ala) was synthesized using allyl amine, para-formaldehyde and new synthesized 1,3,5-tri(p-hydroxyl-phenyl)benzene. The chemical structure of tp-ala was characterized by nuclear magnetic resonance spectroscopy(¹H NMR, ¹³C NMR), Fourier transform infrared spectroscopy(FTIR) and ultraviolet and visible absorption spectroscopy(UV-Vis). The curing behavior of tp-ala was studied by differential scanning calorimetry(DSC) analysis. The thermal and optical properties of cured tp-ala(P-tp-ala) were observed. The results showed that by introducing the allyl-group, the T_g of P-tp-ala was 322 ℃. 5% mass loss temperature was at 356 ℃ and the char yield at 800 ℃ was 61.4%, which were higher than those of the reported trisphenol-based polybenzoxazines. P-tp-ala also showed photoluminescent property. The fluorescence emission wavelength of P-tp-ala under an excitation at 233 nm was at 350 nm. In addition, due to the high aromatic content of P-tp-ala, P-tp-ala had a high refractive index of 1.6325. The high refractive-index characteristic makes P-tp-ala thermoset a potential candidate in antireflective coating.