Chemical Research in Chinese Universities

Chemical Research in Chinese Universities Vol.31 No.1 February 2015

2015, 31(1): 0-0.

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Greener Gd-doped ZnAgInS₃ Quantum Dots for Fluorescent and Magnetic Resonance Imaging Applications

LIU Yang, LI Dongze, ZHANG Ying, LIU Zhihui, XIE Renguo

2015, 31(1): 1-3. doi:10.1007/s40242-015-4344-7

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Hydrothermal Syntheses and Characterization of Two 1D Chain Complexes and Tetra-capped Keggin Clusters

LIU Yabing, DUAN Weijie, CUI Xiaobing, XU Jiqing

2015, 31(1): 4-8. doi:10.1007/s40242-015-4325-x

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Two new compounds, [Ni(en)₂]{[Ni(en)₂]₂[Mo^VI₆Mo^V₂V^IV₈O₄₀(SiO₄)]}[(NH₂)₂(C₂H₄)₂NH]·2H₂O(1) and [Ni(en)₂]{[Ni(en)₂]₂[Mo^VI₅Mo^V₃V^IV₈O₄₀(VO₄)]}(en)·H₂O(2)(en=ethylenediamine), have been hydrothermally synthesized and characterized by elemental analysis, infrared(IR), X-ray photoelectron spectroscopy(XPS), electron spin-resonance(ESR) and thermogravimetric(TG) analysis and single-crystal X-ray diffraction(XRD) analysis. Both the compounds exhibit a 1D chain composed of bi-supporting tetra-capped Keggin clusters and nickle coordination fragments. The 1D chains are further assembled into a 3D supramolecular network with different packing modes via hydrogen bonds. The magnetic susceptibility of compound 1 demonstrates the presence of antiferromagnetic interactions.

Multi-component Hydrogen-bonding Organic Salts Formed from 1-Methylpiperazine with Aromatic Carboxylic Acids: Synthons Cooperation and Crystal Structures

YANG Yu, XU Wenyan, HU Yanjing, WANG Lei, HUANG Keke

2015, 31(1): 9-15. doi:10.1007/s40242-015-4304-2

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1-Methylpiperazine was employed to crystallize with 2,4-dihydroxybenzoic acid and 1,8-naphthalene acid, affording two multi-component hydrogen-bonding salts [(C₅H₁₄N₂)²⁺·(C₇H₅O₄)_2-·H₂O](1) and [(C₅H₁₄N₂)²⁺(C₁₂H₆O₄)²ˉ·2H₂O](2). These two forms of salts are both monoclinic systems with space group P2₁/c(14). The lattice parameters of salts 1 and 2 are a=1.32666(10) nm, b=0.90527(7) nm, c=1.67107(13) nm, β=103.125(1)° and a=1.4950(2) nm, b=0.75242(15) nm, c=1.6563(3) nm, β=92.834(2)°, respectively. Expected classical hydrogen bonds N―H…O and O―H…O appear in the chargetransfer salts, and asymmetric units of these two forms both contain water molecules which play a significant role in building novel supramolecular architectures. Robust hydrogen-bond interactions between 1-methylpiperazine and aromatic acid provide sufficient driving force to direct the two crystals to three-dimensional structures. Weak interactions C―H…O emerging in salts 1 and 2 further enhance their crystal structures. As a consequence, hydrogen-bonding interactions in these compounds afford diverse 3D net supramolecular architectures. Thermal stability of these compounds was investigated by thermogravimetric analysis(TGA).

Structure, Thermal Behavior and Characterization of a New Hybrid Iron Fluoride FeF₄(2,2'-bipyridine)(H₂O)₂

Mouna SMIDA, Hager LITAIEM, Mohamed DAMMAK, Santiago GARCIA-GRANDA

2015, 31(1): 16-20. doi:10.1007/s40242-015-4171-x

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New crystal of FeF₄(2,2'-bipyridine)(H₂O)₂ was prepared by hydrothermal synthesis. Crystalline structure determination is performed from single crystal X-ray diffraction data. The unit cell is monoclinic space group P2₁/n, with cell parameters a=0.9046(5) nm, b=0.7502(5) nm, c=1.9539(5) nm, β=93.307(5)°, V=1.3238(12) nm³ and Z=4. The structure of FeF₄(2,2'-bipyridine)(H₂O)₂ is built up from FeF₄N₂ octahedra coordinated by two nitrogen atoms of the 2,2'-bipyridine molecules, and four fluorine atoms as well as uncoordinated H₂O molecules. Thermal analysis of the title compound showed that the decomposition introduced four steps. IR spectra confirmed the presence of 2,2'-bipyridine molecules. The optical absorption was measured at the corresponding l_max using UV-Vis diffuse reflectance spectrum.

Mass Spectrometric Analysis Revealing Phosphorylation Modifications of Periostin

ZHAO Yueming, SONG Lina, LI Lingxia, LI Xiao'ou, SHI Qinghong, HONG Xin, GUO Jia, FANG Ling, HE Chengyan, LI Hongjun, ZHAO Haifeng

2015, 31(1): 21-24. doi:10.1007/s40242-014-4317-2

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Human periostin was over-expressed in HEK293T cells, which was enriched by nickel ion affinity resin, and further purified by gel electrophoresis. Phosphopeptides contained in the tryptic digestion of the purified periostin were enriched by TiO₂ affinity chromatography, and then analyzed by liquid chromatography-tandem mass spectrometry(LC-MS/MS). LC-MS/MS analysis reveals three phosphorylation modification sites of periostin at IKVIEGpSLQPIIK(682―694), pSLHEKLKQDK(498―507) and p[TT]VLYEC^*C^*PGYM^*R(73―85). The established method could be a great help to profiling the phosphorylation status of periostin under different physiological environments, such as inflammatory and tumor micro-environments.

Preparation of Surface-enhanced Raman Scattering(SERS)-active Optical Fiber Sensor by Laser-induced Ag Deposition and Its Application in Bioidentification of Biotin/Avidin

LIU Chunyu, WANG Shaoyan, FU Cuicui, LI Haibo, XU Shuping, XU Weiqing

2015, 31(1): 25-30. doi:10.1007/s40242-015-4294-0

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A surface-enhanced Raman scattering(SERS) optical fiber sensor was prepared by the laser-induced deposition of Ag nanoparticle membrane on a silica optical fiber tip, which was applied to the real time SERS spectral monitoring on the biorecognition of biotin/avidin. The bioidentification of biotin/avidin was carried out through a indirect method, in which the bioidentification is based on the SERS response signal of a labeled dye(Atto610) after its fluorescence has been quenched totally by the deposited Ag nanoparticle membrane. By SERS monitoring the bioidentification process of biotin/avidin, it has been found that this recognition process is finished in 40 min. The lowest detection concentration of biotin is 1.0×10^-7 mg/mL. This research is promising in the application of immunoassays on line and in vivo.

Studies on the Interaction of Novel Organogermanium Sesquioxides with DNA

GE Shun, ZHAO Ying, SUI Beibei, SHANGGUAN Guoqiang

2015, 31(1): 31-37. doi:10.1007/s40242-015-4198-z

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The affinity and mode of interaction of four novel organogermanium sesquioxides with calf thymus DNA(CT-DNA) and two synthetic oligonucleotides, d(AT)₂₂d(AT)₂₂ and d(GC)₂₂d(GC)₂₂, were investigated by a combination of absorption spectroscopy, DNA thermal denaturalization method, viscosity method, fluorometric technique, and competitive binding study with ethidium bromide(EB). The results show that the organogermanium compounds can interact with DNA by intercalation, the binding ability of the compounds to CT-DNA and the synthetic oligonucleotides was found to be modest(in comparison to the proven intercalators), with binding constants on the order of 10³―10⁵ L/mol, respectively. Generally, the binding of the organogermanium sesquioxides with naphthalene moiety to DNA is stronger than that of the compounds with anthraquinone moiety. And the compounds with anthraquinone moiety have preference for binding to AT-rich duplexes, whereas the compounds with naphthalene moiety have a little preference for binding to GC-rich duplexes. DNA may be the primary effect target.

HPLC-ESI-MS Analysis of Flavonoids Obtained from Tissue Culture of Dracaena cambodiana

WANG Hui, WANG Jiayuan, WU Xiaopeng, SHEN Haiyan, LUO Ying, DAI Haofu, MEI Wenli

2015, 31(1): 38-43. doi:10.1007/s40242-015-4184-5

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Dragon's blood is a traditional medicine and used in many countries with different cultures because of its various therapeutic properties. The main bioactive constituents of dragon's blood are flavonoids, which exhibit va-rious pharmaceutical activities, such as haemostatic, analgesic, anticoagulant, and antimicrobial activities and so on, and have attracted the attention of researchers on the development of new drugs. However, the formation process of dragon's blood in nature is very slow, which cannot meet the demand of pharmaceutical uses. Dracaena cambodiana (D. cambodiana) is one of the resource plants of dragon's blood. During the course of tissue culture of D. cambodiana, 6-benzylaminopurine was added in the medium, then red secretion was discovered in the cultured medium. Twelve compounds(1―12), including 11 flavonoids, were determined via the analysis of constituents of the cultured medium by high performance liquid chromatography-electrospray ionization-mass spectrometry(HPLC-ESI-MS) and the results were compared with that of the standards isolated from dragon's blood. Among compounds 1―12, 4,4'-dihydroxy-2-methoxydihydrochalcone(5), 4,4'-dihydroxy-2,6-dimethoxydihydrochalcone(6) and (2S)-7,3'-dihydroxy-4'-methoxyflavane(9) were major compounds of the red secretion, with contents of 15.70, 7.10 and 57.23 mg/L, respectively. Therefore, it is promising that flavonoids from dragon's blood can be obtained from the tissue culture of its resource plants for the purpose of drug development.

Enhanced Multi-phosphopeptide Enrichment and Nano LC-ESI-qTOF-MS Detection Strategy Using Click OEG-CD Matrix

ZHAO Yanyan, WANG Liheng, GUO Zhimou, CHI Xiaofei, MA Xiaochi, QI Yan, FANG Shinong, LI Xiuling, LIANG Xinmiao

2015, 31(1): 44-52. doi:10.1007/s40242-014-4179-7

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Detection and determination of multi-phosphopeptides from protein digestion products are difficult due to the low abundance and ion-suppression effect arised from the existence of their high-abundance counterparts. Click OEG-CD[olio(ethylene glycol)(OEG) linked β-cyclodextrin(CD)] matrix has shown excellent performance in phosphopeptide enrichment. However, few multi-phosphopeptides were detected previously. In this investigation, an improved method aiming at enhancing the enrichment selectivity and mass spectrometry(MS) detection of multi-phosphopeptide was developed via optimizing the sample loading amount on per mg of matrix. Mass spectra were obtained on a Nano liquid chromatography-electrospray ionization-quadrupole time of flight-mass spectrometry (LC-ESI-qTOF-MS). The enrichment selectivity of double-phosphopeptide could be enhanced with the increase of loading amount on per mg of matrix when taking the mixture of mono-, double-, and non-phosphopeptides as probe. Furthermore, the multi-phosphopeptide enrichment selectivity was enhanced under the condition of optimized loading amount when taking the product of typtic digestion α-casein as test sample. When the loading amount was 573 pmol/mg matrix, up to 20 α-casein phosphopeptide signals(including 15 multi-phosphopeptides) were detected. The result is much better than that of our previous report. The reduction of ion-suppression effect arised from the existence of high-abundance non-or mono-phosphopeptides and the stronger interactions between multi-phosphopepides and the matrix were contributed to the result. The study could be helpful to the better utilization of Click OEG-CD matrix in the enrichment of multi-phosphopeptide from complex biosamples in the subsequent investigation.

Indole-tolerant Oxidation of 1,2-Diarylalkynes to 1,2-Diketone Derivatives

CHENG Xu, LI Xiaolong, WAN Weili, HAO Wenmei, HAI Li, WU Yong

2015, 31(1): 53-59. doi:10.1007/s40242-015-4373-2

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A new indole-tolerant oxidation condition for the synthesis of 1,2-diketone derivatives from the corresponding 1,2-diarylalkynes was described. By screening a series of oxidation systems on alkynes linked with indole and different substituted aromatic ring, the DMSO/PdCl₂/CuCl₂ system afforded moderate to good yields despite the existence of electron-rich indole ring.

Synthesis and Characterization of Novel Azo-containing or Azoxy-containing Schiff Bases and Their Antiproliferative and Cytotoxic Activities

SU Ran, LÜ Lei, ZHENG Songzhi, JIN Yinghua, AN Shengji

2015, 31(1): 60-64. doi:10.1007/s40242-015-4355-4

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A series of novel Schiff base derivatives was designed and synthesized from 3,3'-azobenzaldehyde and 3,3'-azoxybenzaldehyde. The newly synthesized compounds were characterized by FTIR, ¹H NMR, MS and elemental analysis and tested for their in vitro antiproliferative activities against HeLa cell lines. At the same time, the impact on the antitumor activity of the sulfanilamido, benzamido, phenolic hydroxyl or thiourea groups was investigated and discussed. Compounds 4, 6 and 10 were found to exhibit strong cytotoxic activity.

Aminobromination of Ethyl α-Cyanocinnamate Derivatives with 1,3-Dibromo-5,5-dimethylhydantoin(DBDMH) as Nitrogen and Halogen Sources

CHEN Zhanguo, LIU Yali, HU Junli, LIU De'e

2015, 31(1): 65-70. doi:10.1007/s40242-015-4341-x

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1,3-Dibromo-5,5-dimethylhydantoin(DBDMH) was found to be a new and efficient nitrogen/halogen source for the aminobromination of ethyl α-cyanocinnamate derivatives catalyzed by K₃PO₄. The reaction afforded the aminobrominated products in high yields at room temperature, and the full regiospecificity of all the products were achieved. A possible pathway involving a Michael addition for this aminobromination was suggested.

Synthesis and Biological Evaluation of Novel Saccharin Derivatives Containing 1,2,3-Triazole Moiety

TANG Xiaobin, LI Zhenghui, LI Yonghong, LIU Wei, YU Peng, LI Lixin, GUO Yu, YANG Cheng

2015, 31(1): 71-77. doi:10.1007/s40242-015-4309-x

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A series of novel saccharin derivatives containing 1,2,3-triazole moiety was synthesized in satisfactory yields. The structures of all the compounds were elucidated and confirmed by Fourier transform infrared(FTIR) spectroscopy, ¹H and ¹³C nuclear magnetic resonance(¹H NMR, ¹³C NMR) spectroscopy, and high resolution mass spectrometry(HRMS). The bioassays indicated that most of the title compounds displayed some extent herbicidal activities at 100 μg/mL.

Synthesis and Antitumor Activity of Capecitabine Derivatives

JIA Xuedong, LIU Xiujun, WANG Jian, WANG Minghua, GUO Huiyuan, LIU Mingliang

2015, 31(1): 78-83. doi:10.1007/s40242-015-4282-4

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A series of capecitabine derivatives with a Boc group at the N⁴-position was synthesized and their in vitro antitumor activities against HepG2(liver hepatocellular carcinoma) were primarily evaluated. Some compounds were chosen for further evaluation of their in vivo efficacy on nude mice xenografted human hepatoma HepG2. The results showed that compounds 3 and 6 had considerable in vivo activity against HepG2, with tumor growth inhibition rates of 70% and 64% on day 21, respectively, and 56% and 55% on day 35, respectively, which are roughly comparable to capecitabine(74% and 59% on days 21 and 35, respectively).

Structural Study on Four co-Crystals of N-Containing Heteroaromatics with Iodofluorobenzene

JI Baoming, DENG Dongsheng, WANG Weizhou, WANG Ke, HE Mengli

2015, 31(1): 84-90. doi:10.1007/s40242-015-4145-z

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N-Containing heteroaromatics 1,2,4,5-tetra(pyridin-3-yl)benzene[1,2,4,5-T(3-PY)B] and 1,2,4,5-tetra-(pyridin-4-yl)benzene[1,2,4,5-T(4-PY)B] were each co-crystallized with 1,2-diiodo-tetrafluoro-benzene(1,2-DITFB), or 1,4-diiodo-tetrafluoro-benzene(1,4-DITFB), respectively, generating four co-crystals, namely, (1,2-DITFB)₄·[1,2,4,5-T(3-PY)B](1), (1,2-DITFB)₄·[1,2,4,5-T(4-PY)B](2), (1,4-DITFB)₂·[1,2,4,5-T(3-PY)B]·CHCl₃(3), and (1,4-DITFB)·[1,2,4,5-T(4-PY)B]·2CHCl₃(4). This study takes aim at providing an insight into the relative importance of fundamental solid state halogen bonding interactions(i.e., halogen…N, halogen…halogen, and halogen…π) in systems. The effects of the donor and acceptor on supramolecular assembly and the crystal structure determined interactions were discussed. The N…I halogen bonds are the main directing interactions responsible for the observed structures. In compounds 1 and 2, the donors exhibited lower-than-expected supramolecular connectivity. In spite of this, co-crystal 2 exhibits polymeric structures consisting of infinite one-dimensional(1D) double-zigzag chains of alternating electron donor and acceptor. The basic structure of co-crystals 3 and 4 is also infinite 1D chain. Therefore, the 1D halogen bonded supramolecular assemblies can be obtained by matching the appropriate donor and acceptor.

A Surfactant-stable Bacillus pumilus K9 α-Keratinase and Its Potential Application in Detergent Industry

GONG Jinsong, WANG Yue, ZHANG D, an, LI Heng, ZHANG Xiaomei, ZHANG Rongxian, LU Zhenming, XU Zhenghong, SHI Jinsong

2015, 31(1): 91-97. doi:10.1007/s40242-015-4351-8

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An α-keratinase producing strain was isolated with wool as the sole carbon and nitrogen source and identified as Bacillus pumilus K9. The major amino acids liberated from the keratin degradation of wool by B. pumilus K9 were glutamic acid and leucine. The α-keratinase was purified to electrophoretic homogeneity with a molecular weight of 32000. The purified enzyme exhibits an optimum activity at 60 ℃ and pH=9.0. It was stable at pH values between 8 and 11. Bacillas pumilus keratinase displays a high activity towards casein, keratin, wool and feather, which indicates its wide application range. The keratinase was completely inhibited by phenylmethyl-sulfonyl fluoride(PMSF) and β-mercaptoethanol, and moderately inhibited by ethylemediamine-tetraacetic acid(EDTA), sugges-ting it is a metallo-cysteine keratinase. This enzyme could remain stable that could even be promoted in the presence of surfactants, including sodium dodecyl sulfate(SDS), Tween and Triton. And Tween 40 and Triton X-100 could substantially enhance the activity of the enzyme by 54% and 35%, respectively. It may indicate the prominent feature of the keratinase to tolerate surfactants. The enzymatic properties distinguish this keratinase from others in the literature. Furthermore, this enzyme is extremely stable in the presence of a commercially available detergent with 1% concentration. Detergents ARIEL, Bluemoon and WhiteCat can enhance the activity of the keratinase by 43.56%, 15.22%, and 22.48%, respectively.

Clone, Purification and Characterization of Thermostable Aminopeptidase ST1737 from Sulfolobus tokodaii

YU Xiaoxiao, HAO Weiwei, XIE Guiqiu, WANG Yingwu, GAO Renjun

2015, 31(1): 98-102. doi:10.1007/s40242-014-4314-5

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The aminopeptidase gene from thermophilic archaea Sulfolobustokodaii was cloned and expressed in Escherichia coli BL21 codon-plus(DE3). To overexpress the aminopeptidase, the vector pET32a was constructed, in which the target gene was fused with the genes of histidine-tag and thioredoxin(Trx). The expressed protein was purified using Ni²⁺-column affinity chromatography and ion exchange chromatography and cleft with enterokinase(EK) to obtain the purified aminopeptidase(ST1737). The biochemical and enzymic properties of the expressed ST1737 were characterized. The results show that its optimal pH and temperature are 8 and 80 ℃, respectively. The half-life of ST1737(0.2 mg/mL) is about 85 h at 90 ℃, indicating that the enzyme exhibits an excellent thermostability. The activity of ST1737 could still maintain over 85% after its treatment at 25 ℃ in different buffers with a pH range of from 6.0 to 10.5 for 24 h, demonstrating that ST1737 is stable in neutral or slight alkali environment. The enzyme shows a high activity for the substrates, such as unmodified peptide Asp-Ala, while the pNPC₈ shows an optimal esterase substrate specificity. These results indicate that the enzyme is a bifunctional enzyme, and different from the aminopeptidase reported before.

Retention Mechanism of Phenolic Compounds in Subcritical Water Chromatography

WU Yichao, DENG Xiuqing, MAO Yinchun, ZHANG Yan, LIU Jiaqin, RONG Li, XU Zhihong

2015, 31(1): 103-106. doi:10.1007/s40242-015-4360-7

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The transfer enthalpies and entropies of hydroxyl and nitryl in different mobile phase systems were compared by van't Hoff curve. Results suggest that the presence of acetonitrile and methanol in the mobile phase may decrease the interaction of solute and stationary phase with respect to subcritical water, thereby reducing the contribution of enthalpy to the retention. Retention mechanisms of phenolic compound appear to be more similar in subcritical water and water/methanol systems on the PRP-1 column. Hydrogen bond in subcritical water system plays a very important role in the retention of the phenols.

Quantitative Analysis of Fe Content in Iron Ore via External Calibration in Conjunction with Internal Standardization Method Coupled with LIBS

SHENG Liwen, ZHANG Tianlong, WANG Kang, TANG Hongsheng, LI Hua

2015, 31(1): 107-111. doi:10.1007/s40242-014-4318-1

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The external calibration in conjunction with internal standardization(ECIS) coupled with laser-induced breakdown spectroscopic(LIBS) technique was proposed to perform the quantitative analysis of Fe content in iron ore. The plasma temperature and the electron number density were calculated to prove that the plasma was under local thermodynamic equilibrium(LTE) conditions and to ensure that the integral intensities of Fe I lines were reasonable. In addition, the result of the quantitative analysis shows a content of (20.26±0.59)% by mass of Fe in the iron ore. It was determined by four calibration curves, drawn for four emission lines of Fe I(373.48, 373.71, 404.58 and 438.35 nm) normalized by Mn I line, base on the ECIS method which can eliminate the influence of matrix effect and improve the accuracy of quantitative analysis, compared with the standard addition method. Both the results of these two analytical methods were compared with that listed in the Standard Substance Certificate. The percentage content of Fe in the same sample of iron ore by the ECIS method was (20.17±0.08)% by mass, which shows a good performance to analyze the Fe content of iron ore in combination with LIBS.

Structural and Theoretical Studies of a New Cu^I-Cu^I Complex Bearing Bulky Unsymmetrical Benzamidinate Ligand

PAN Chengling, TANG Guodong, CAO Zhi, XU Jiqing, SHENG Shaoding

2015, 31(1): 112-116. doi:10.1007/s40242-015-4287-z

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Density functional theory(DFT) calculations unambiguously verify that there is little or no direct metal-metal bonding in the dinuclear copper(I) benzamidinate complex [Cu₂(L^RR')₂](2){L^RR'=[PhC(NR)(NR')]^-(R= 2,6-ⁱPr₂C₆H₃, R'=SiMe₃)} with a short Cu-Cu distance[0.24454(4) nm].

Synthesis and Electrochemical Studies of Carbon-modified LiNiPO₄ as the Cathode Material of Li-ion Batteries

ZHANG Ying, PAN Yue, LIU Jia, WANG Guiling, CAO Dianxue

2015, 31(1): 117-122. doi:10.1007/s40242-015-4261-9

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Well-crystallized olivine LiNiPO₄ and carbon-modified LiNiPO₄(LiNiPO₄/C) were synthesized by a combined solvothermal and solid state reaction method using water-benzyl alcohol two-phase solvent. The structure and morphology of the prepared LiNiPO₄ were systematically characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The LiNiPO₄ particles are up to around 2 μm in diameter while the particle size of LiNiPO₄/C is about 100—200 nm. At a current rate of 0.05 C(1.00 C=167 mA/g, corresponding to one Li⁺ intercalation/deintercalation), LiNiPO₄ and LiNiPO₄/C presented a high initial specific capacity of 157 and 220 mA·h/g, respectively. The capacity of LiNiPO₄/C is 72% larger than that of LiNiPO₄ at 0.1 C. The LiNiPO₄/C cathode exhibits a superior electrochemical performance in comparison with LiNiPO₄, revealing that carbon modifying is an effective method to improve the ionic diffusion and electronic conductivity of cathode material LiNiPO₄. Furthermore, lithium ion diffusion coefficients of LiNiPO₄ and LiNiPO₄/C are 1.80×10^-15 and 1.91×10^-14 cm²/s, respectively, calculated via the data from electrochemical impedance spectra.

Theoretical Studies on Dielectric Breakdown Strength Increasing Mechanism of SF₆ and Its Potential Alternative Gases

ZHANG Hui, SHANG Yan, CHEN Qingguo, HAN Baozhong

2015, 31(1): 123-129. doi:10.1007/s40242-014-4255-z

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A theoretical investigation on the dielectric insulation mechanism of sulfur hexafluoride(SF₆) and its potential alternative gases at the atomic and molecular levels was made. The electronic structures of the molecules of them were calculated at the B3LYP/6-311+G(d,p) level. The HOMO-LUMO energy gaps, ionization potentials, electron affinities, and dipole moments of the studied molecules at the ground state were obtained. The 11 isomerization reactions, with the harmonic vibration frequencies of the equilibrium geometries and the minimum energy path by the intrinsic reaction coordinate theory, were also obtained at the same level. The results show that the insulation gas, with the larger HOMO-LUMO energy gap, the higher ionization potential and the stronger electron affinity, can increase the dielectric breakdown strength efficiently, which is in good agreement with the available experimental finding. We suggested that the molecule with isomerization reaction occurring can dissipate the energy of hot electrons availably, which is favorable to the dielectric breakdown strength increasing for the SF₆ potential alternative gas.

Adsorption of CO₂ and H₂ on Nitrogen-doped Porous Carbon from Ionic Liquid Precursor

ZHANG Lingna, CAI Kun, ZHANG Feng, YUE Qunfeng

2015, 31(1): 130-137. doi:10.1007/s40242-015-4224-1

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Nitrogen-doped mesoporous carbon material was prepared via a simple one-step thermolysis method via the carbonization of ionic liquid, 1-cyanomethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([MCNIm]⁺[Nf₂T]^-). The nanostructure of the resultant carbon material was characterized by X-ray diffraction(XRD) and transmission electron microscopy(TEM) and the types of N-containing groups of the carbon material were investigated by X-ray photoelectron spectroscopy(XPS). The N-content of the carbon material is 18.6%(mass fraction) based on the elemental analysis. The produced mesoporous carbon material was further used as the solid sorbent for H₂ and CO₂. The hydrogen uptake capacity and H₂ isosteric heat of the carbon material were discussed. Furthermore, the nitrogen-containing carbon material as good sorbent shows relatively high adsorption and separation ability for CO₂ from CH₄, for which the heat of CO₂ adsorption(Q_st) is 31.8 kJ/mol. The mesoporous structure and nitrogen functionality make the carbon material with high adsorption capacity and selectivity for CO₂ and ability to store H₂, indicating that this kind of nitrogen-doped carbon material originated from ionic liquids is a promising sorbent material for high-performance separation and adsorption.

Synthesis of Submicrometer-sized Sn-MCM-41 Particles and Their Catalytic Performance in Baeyer-Villiger Oxidation

CHEN Na, JIANG Yanqiu, CHENG Wenjing, LIN Kaifeng, XU Xianzhu

2015, 31(1): 138-143. doi:10.1007/s40242-014-4204-x

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Submicrometer-sized tin-containing MCM-41 particles with a size of several hundred nanometers(Sn-MCM-41/SMPs) were rapidly prepared with tin chloride as tin source and tetraethyl orthosilicate as silicon source via a dilute solution route in sodium hydroxide medium at room temperature. The characterization results show the highly ordered hexagonal mesopores and tetrahedral Sn species in Sn-MCM-41/SMPs. The material proved to be active and selective for Baeyer-Villiger oxidation of adamantanone with aqueous H₂O₂. Notably, Sn-MCM-41/ SMPs displayed a higher initial reaction rate and turnover number(TON) than common micrometer-sized Sn-MCM-41 large particles(Sn-MCM-41/LPs), mainly attributed to the accelerated diffusion of the reactants and enhanced accessibility to the catalytic Sn species via shorter mesopore channels in Sn-MCM-41/SMPs. Furthermore, Sn-MCM-41/SMPs could be reused without the loss of activity after five runs, indicating that Sn active sites in the submicrometer-sized particles are remarkably stable. The study shows that decreasing particle size of Sn-MCM-41 in submicrometer scale is an effective way to achieve catalysts for Baeyer-Villiger oxidations with improved catalytic performance.

Performance and Mechanisms of Fluoride Removal from Groundwater by Lanthanum-aluminum-loaded Hydrothermal Palygorskite Composite

ZHANG Shengyu, LÜ Ying, LIN Xueyu, ZHANG Yuling, SU Xiaosi

2015, 31(1): 144-148. doi:10.1007/s40242-015-4126-2

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Lanthanum-aluminum loaded hydrothermal palygorskite(La-Al-HP) composite was prepared and selected as adsorbent for the fluoride removal from simulated groundwater. The adsorbent was characterized by scanning electron microscopy(SEM), Brunauer-Emmet-Teller(BET) analysis, X-ray diffraction(XRD) analysis and X-ray photoelectron spectroscopy(XPS). SEM visualization shows that the dense surface structure of raw HP appeared loose and presented micro canals after modification. The BET analysis also proved the specific surface area of La-Al-HP composite(95.58 m²/g) was higher than that of the raw HP(34.31 m²/g). Subsequently, the adsorption capacity of La-Al-HP composite was demonstrated in adsorption experiments. The kinetics of fluoride ion adsorption into La-Al-HP composite followed the pseudo-second order with a correlation coefficient of 0.997. The isotherm data was well fitted with the Langmuir model. The monolayer adsorption capacity of La-Al-HP composite was 1.30 mg/g. The XRD and XPS results reveal that the La³⁺ and Al³⁺ ions were loaded on the surface of modified HP and the fluoride ion was adsorbed onto the La-Al-HP composite. A large amount of La-Al-O composite oxide existing on the surface of La-Al-HP composite might be the immanent cause for the excellent adsorption capacity of fluoride ions.

Impact of Stable Protein-protein Interaction on Protein Conformational Space

LI Wenzhao, MENG Wei, TIAN Pu

2015, 31(1): 149-155. doi:10.1007/s40242-015-3402-5

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Backbone dihedral angle based clustering approach was applied to investigate the effect of protein complexation on backbone conformational space and the effect on protein dynamics. Three representative enzyme-inhibitor complexes and their comprised proteins were used as models for small-and moderate-sized globular proteins to compare available backbone conformational space before and after complexation. Microsecond time scale molecular dynamic simulations were generated to ensure sufficient statistics. The result suggests that stable protein-protein interactions lead to redistribution of protein backbone mobility and restriction of the protein backbone conformational space, especially for short time scale motions. Surprisingly, these effects are found to be uncorrelated with protein-protein interaction surface. Consistent with many experimental and computational observations, our results indicate that both induced-fit and conformational selection models play roles in stable protein complexation process, with the dominant role being different for different protein complexes.

Facile Synthesis of Mesoporous Si-containing γ-Al₂O₃Nanofiber with Enhanced Thermal Stability

HU Fang, WANG Yamin, LAI Xiaoyong, WU Yusheng, DU Fei, WANG Chunzhong

2015, 31(1): 156-159. doi:10.1007/s40242-015-4322-0

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Mesoporous γ-Al₂O₃ nanofiber was prepared via a simple reverse precipitation route using Si-containing Al(OH)₃ and HNO₃ as raw materials. The resultant Si-containing mesoporous γ-Al₂O₃ nanofiber exhibited high surface area of 320 m²/g, large pore volume of 1.17 cm³/g and large pore size of 10.5 nm. The introduction of Si element remarkably enhanced the thermal stability of mesoporous γ-Al₂O₃. The as-prepared nanofiber could maintain relative high surface area(110 m²/g) and pore volume(0.73 cm³/g) up to 1100 ℃. The effects of various experimental conditions, such as pH value, reaction temperature and aging temperature on the structural properties of the mesoporous γ-Al₂O₃ were also investigated.

Antibacterial Activity of Polymeric Quaternary Ammonium Compounds Tuned by Incorporating Hydrophilic co-Monomer

ZUO Huajiang, WEN Wanhua, WU Dingcai, FU Ruowen, TANG Chunyi

2015, 31(1): 160-166. doi:10.1007/s40242-015-4248-6

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Copolymers of quaternary ammonium monomer(QAM) and hydrophilic co-monomer were successfully synthesized by free radical polymerization. It was discovered that the hydrophilic co-monomers with poor antibacterial activity significantly enhanced the activity of QAM substituted with a long alkyl chain[i.e., N,N-dimethyl-N-dodecyl methacrylate ammonium bromide(DMAEMA-DB)]. When a suitable molar ratio of DMAEMA-DB to co-monomer was selected, the activity of the copolymers was up to 123 times that of the homopolymer of DMAEMA-DB against S. aureus, and 282 times that of it against E. coli. But unlike DMAEMA-DB, the co-monomers might weaken the activity of QAM substituted with a short alkyl chain[i.e., N,N-dimethyl-N-butyl methacrylate ammonium bromide(DMAEMA-BB)]. Moreover, it was found that copolymers of DMAEMA-DB were much more biocidal than those of DMAEMA-BB. Therefore, it could be speculated that the long alkyl chain plays an important role in the antibacterial activity, and that the hydrophilic co-monomers are beneficial to polymeric guaternary ammonium compounds(PQACs) to exert the positive effect of the long alkyl chain to the greatest degree.

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