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25 March 2009, Volume 25 Issue 2

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Content of Chemical Research in Chinese Universities Vol.25 No.2(2009)

2009, 25(2):  0-0.  doi:

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Articles

Synthesis, Structure, and Photoluminescence Property of a Novel One-dimensional Inorganic-organic Hybrid Gallophosphate JGP-2

YANG Yu-lin , FAN Rui-qing , JIANG Zhao-hua , WANG Fu-ping , LIU Yun-ling , PANG Wen-qin

2009, 25(2):  127-131.  doi:

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A novel one-dimensional inorganic-organic hybrid gallophosphate compound, Ga(2,2'-bipy)(HPO₄)·(H₂PO₄)(denoted JGP-2) was synthesized hydrothermally with 2,2'-bipyridine as a ligand and characterized by X-ray powder diffraction (XRD), elemental analysis, inductively coupled plasma(ICP), TGA analysis, solid-state ³¹P NMR, and luminescence spectra and structurally determined by single-crystal X-ray diffraction analysis. JGP-2 crystallized in the triclinic system, space group Pī(No.2), with a=0.7818(1) nm, b=0.8611(2) nm, c=1.0908(2) nm, V=0.6727(2) nm³ and Z=2 with R₁=0.0223. The structure of JGP-2 was built up by alternate arrangement of GaO₄N₂ octahedra, and HPO₄(or H₂PO₄) tetrahedra to form an infinite one-dimensional corner-sharing-corner(CSC) chain. Through P sites, the CSC chains link with an unusual edge-sharing dimmer, Ga₂F₄(H₂O)₂, giving rise to a 4,10-membered ring net layered structure of JGP-7. On excitation at 254 nm, JGP-2 can emit strong blue light at λ_max=388 nm. JGP-7 presents a strong fluorescence emission band centered at 394 nm(λ_ex=340 nm), the emission energy of JGP-7 is red-shifted compared with that of JGP-2.

Preparation and Characterization of Cu₃V₂O₇(OH)₂·2H₂O Hollow Spheres from Na₂V₆O₁₆·3H₂O Nanobelts

YANG Fang , JI Tian-hao , DU Hai-yan , SUN Jia-yue , YANG Qing-lin , GE Guang-lu

2009, 25(2):  132-137.  doi:

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Monoclinic Cu₃V₂O₇(OH)₂·2H₂O(copper polyvanadate) hollow spheres were prepared with Na₂V₆O₁₆·3H₂O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis(TGA) and X-ray photoelecton spectroscopy(XPS). The morphology and size were observed by scanning electron microscopy(SEM). We found that the Kagomé staircase-structural copper polyvanadate hollow spheres with an average diameter of 7 µm could be easily synthesized via the reaction of Na₂V₆O₁₆·3H₂O nanobelts with sufficient copper sulfate. The dielectric property of the copper polyvanadate demonstrates that dielectric loss hardly changes when the frequency of applied electric field is higher than 100 kHz. The formation process of the hollow spheres is discussed in detail by the observation of a series of products prepared for different reaction time.

Novel Photoinitiated Synthesis, Characterization, Thermal Kinetics, and Mechanism of Complex of Potassium Hexacyanoferrate with Imidazole

MAJID Kowsar , AHMAD Siraj , MALIK Mukhtar Ahmad

2009, 25(2):  138-142.  doi:

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Photoinitiated substitution complex of [Fe(CN)₆]^4– with imidazole has been synthesized and characterized. On the basis of elemental analysis, the empirical molecular formula of the complex is K₄[Fe(CN)₅(C₃H₄N₂)]·4H₂O. The substitution of aquo ligand produced as a result of photoexcitation by imidazole has been confirmed by various spectroscopic thechniques like UV-Vis, FTIR, NMR, and SEM techniques. The characteristic FTIR and NMR absorption peaks for different entities present support the assigned formula. The presence of cyanide and imidazole ligands is shown by FTIR absorption peaks at 2046 cm^–1 due to ν(C≡N) and at 1447 and 1619 cm^–1 due to ν(C=N) and ν(C=C) stretching vibration of the aromatic ring of imidazole, hence, confirming the assigned formula and photoinitiated substitution process. ¹H NMR also shows the peaks for aromatic hydrogen confirming again the presence of imidazole in the complex, further supporting the successful photoinitiated process. The water outside the coordination sphere has been confirmed from FTIR peaks and thermal analysis. Thermal kinetics and mechanistic studies have also been carried out by TG and DSC. Thermodynamics parameters such as activation energy(E_a), preexponential factor(A), and entropy of activation(ΔS^#) have been calculated for each step via different methods like Doyle's, Coats, and Redfern and Arrehenius.

Flexible Aluminum Nanobowls for Alternative Preparation of Individual or a Small Number of Nanoparticles

SUN Yan , CHEN Xin , YUE Yang , ZHANG Rong-jun , DAI Ning

2009, 25(2):  143-146.  doi:

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The nanoscale aluminum bowls were derived from the porous alumina and were used as the flexible nanoscale reactors for the preparation of nanoparticles. Both single source precursor and preprepared nanoparticles were induced in the nanobowls by melting the precursor/polymer films spin-coated on aluminum nanobowls for the formation of nanostructural composites in the nanobowls. We have prepared a single nanoparticle or just a small number of metal(e.g. Pt) nanoparticles or semiconductor nanoparticles(e.g. CdSe or CdSe/ZnS core-shell nanostructures) in the nanobowls.

Controlled Synthesis of Nanoscale CdTe Urchins

BAO Jian, SHEN Yue, SUN Yan, YUE Yang, CHEN Xin , DAI Ning

2009, 25(2):  147-150.  doi:

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We presented a simple route to prepare nanoscale CdTe urchins in a tri-n-octylphosphine oxide(TOPO) system. CdTe urchins consisted of a core and several attached arms. The arms were ca. 3 nm wide, and their lengths could be controlled with the reaction time. The authors investigated the optical absorption and structural properties of the prepared CdTe. The lengths of the arms could be tuned into CdTe nanourchins, which led to a change in the photophysical properties of the nanoscale CdTe urchins. The results, including transmission electron microscopy(TEM) and absorption spectra, indicated that mesoporous silica and aminopropyltriethoxysilane(APTES) contributed to the formation of nanoscale CdTe urchins.

Simultaneous Voltammetric Determination of Three Herbicides in Food and Water Samples with the Aid of Chemometrics

NI Yong-nian , WANG Lin , KOKOT Serge

2009, 25(2):  151-154.  doi:

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Differential pulse stripping voltammetry method(DPSV) was applied to the determination of three herbicides, ametryn, cyanatryn, and dimethametryn. It was found that their voltammograms overlapped strongly, and it is difficult to determine these compounds individually from their mixtures. With the aid of chemometrics, classical least squares(CLS), principal component regression(PCR) and partial least squares(PLS), voltammogram resolution and quantitative analysis of the synthetic mixtures of the three compounds were successfully performed. The proposed method was also applied to the analysis of some real samples with satisfactory results.

Synergetic and Antagonistic Effects of Cadmium on Adsorption of Atrazine on Surficial Sediments

LI Yu , GAO Qian , WANG Xiao-li , DONG De-ming , WANG Ao

2009, 25(2):  155-160.  doi:

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Co-contamination of atrazine(AT) and cadmium(Cd) on the surficial sediments(SSs) and natural suface coating samples(NSCSs) was investigated via thermodynamic adsorption experiments. The results show that surface coatings have a stronger ability to adsorb AT owing to their higher active components compared with surficial sediments. Synergetic and antagonistic effects of Cd on the adsorption of AT were observed. Cd at a lower concentration(≤4.0 mg/L) in the solid/liquid phase enhanced AT adsorption onto the surficial sediments(surface coatings), while the adsorption of AT would be inhibited at a Cd concentration of more than 8.0 mg/L: AT coordinates strongly to Cd, and AT-Cd complexes seem to be more strongly adsorbed on sediments than AT alone, and at the adsorption of AT can take place on the sites where Cd has been previously adsorbed and Cd acts as a bridge for the interaction between sediments and AT. With the increase of Cd concentration, the superfluous Cd may hold much more adsorption sites and thus inhibits the adsorption of AT. Meanwhile, the effects of co-existed AT on Cd adsorption on SSs(NSCSs) were insignificant since Cd has a stronger competitive ability to be absorbed on SSs(NSCSs). The present study could be useful in predicting interactions of the metal ions with herbicides and potentially aid the design of remediation strategies for contaminated sediments and groundwater.

Furans-Maleimides Diels-Alder Reactions in Protic Ionic Liquid

XAWKAT Ahmat , ABLAJAN Keyume , HIRAKU Shinozaki

2009, 25(2):  161-168.  doi:

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The authors have studied the Diels-Alder reactions between furan derivatives and maleimide derivatives in an ionic liquid and have found that higher reactivity can be obtained in a protic ionic liquid [Mim]Tf₂N than in the conventional organic solvent. Furthermore, in the Diels-Alder reactions of 2- and 2,5-alkylfurans with N-alkylma- leimide, the reactivity increases by extending the alkyl chain length of N-alkylmaleimide. In addition, it was demonstrated that endo-selectivity increases when 2,5-disubstituted furans are used. These results will be explained by comparing the stability of the Diels-Alder adduct with that of the products obtained from the reactions of 2-substituted furans and 2,5-disubstituted furans.

Guanidinium Lactate Ionic Liquid: An Efficient and Recycling Catalyst for Michael Addition Reaction

LIANG Da-peng , XIN Xin , GAO Han , DUAN Hai-feng , LIN Ying-jie

2009, 25(2):  169-173.  doi:

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A facile and efficient 1, 4-conjungate addition(Michael addition) reaction of active methylene compounds to α,β-unsaturated compounds, catalyzed by guanidinium lactate ionic liquid(IL9), has been developed. A range of chalcones and nitroalkenes together with active methylene compounds have been converted smoothly to the corresponding products in high yields.

Convenient Synthesis of Substituted Quinoxalines and 2H-Benzo[b][1,4]oxazines in Water

DING Chang-jiang , WANG Yan , ZHANG Wei-wei , LIU Li , LIANG Yong-jiu , , DONG De-wen

2009, 25(2):  174-177.  doi:

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A facile and convenient synthesis method has been developed for substituted quinoxalines and 2H-benzo[b][1,4]oxazines from the reactions of -bromoketones with benzene-1,2-diamine and 2-aminophenol, respectively, which were catalyzed by tetrabutylammonium bromide(TBAB) in aqueous basic media.

Synthesis and Self-assembling of Coumarin-based Low-molecular Weight Organogelators

CHEN Guo-jun, XUE Peng-chong, LU Ran , SONG Dong-po, BAO Chun-yan, XU Ting-hua , ZHAO Ying-ying

2009, 25(2):  178-182.  doi:

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Four coumarin derivatives(4a―4d) with different alkoxy chains were synthesized. It was found that compound 4d showed a better gelation ability than the other compounds, for example, it could self-assemble into organogels in various organic fluids via ultrasound treatment or heating-cooling process, whereas compound 4c could only gel in a few mixed solvents and compounds 4a, 4b could not form organogel. The results from fluorescent and FTIR spectra indicate that π-π interaction had an effect on the formation of the organogels of compound 4d besides H-bonding and van der Waals interaction, which were the driving forces for the self-assembling of compound 4c in gel state. The gel of compound 4d in toluene could emit strong fluorescence under UV irradiation and the [2+2] cyclo-addition was suggested by ¹H NMR and fluorescence spectroscopy. This light-sensitive organogel might find application in optical materials.

Ultrasound-assisted Highly Efficient Reduction of Nitroarenes to Corresponding N-Arylhydroxylamines

SHI Qi-Xun, LU Rong-wen , HAO Xin-yu, LU Lian-hai , ZHANG Shu-fen

2009, 25(2):  183-188.  doi:

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A convenient, environmentally benign, and highly efficient protocol for the preparation of N-aryl- hydroxylamines from the corresponding nitroarenes in a Zn/HCOONH₄/CH₃CN system under ultrasound is described. The advantages of the present method include high chemoselectivity, simple and practical work-up procedure and high yield.

Solid-phase Synthesis of Thymopentin Derivative and Its Immune Regulatory Activity

LIANG Yong-tao , MI Hao-yu , WANG Ming-zhe , YU Li-ya , LIU Zhong-hui , WANG En-si,

2009, 25(2):  189-192.  doi:

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Thymopentin derivative(septapeptide) was prepared by means of the solid-phase peptide synthesis method in which stepwise and segment condensations were involved. The structures of the key intermediate and target molecule were confirmed by ESI-MS, elementary analysis, IR, ¹H NMR and ¹³C NMR spectrometries in our experiments. In this study, the authors found that both thymopentin derivetive(septapeptide) and thymopentin could promote T cell proliferation and increase of E-rose fomation cells.

Tetraarsenic Tetrasulfide Induced Colon Cancer ls174t Cells Apoptosis

GUO Xing-gang, DONG Xin-shu , CHEN Jie

2009, 25(2):  193-197.  doi:

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To explore the functional mechanism of tetraarsenic tetrasulfide(As₄S₄) against the growth and proliferation of colon cancer cells ls174t, MTT method was used to observe the functions of tetraarsenic tetrasulfide for the inhibition of cells ls174t in vitro. Transmission electron microscope was used to observe cell morphologies. FCM assay was performed to measure the change of cell cycle. RT-PCR method was used to detect the expressions of bcl-2 and bax mRNA. Westernblot method was used to detect the expressions of bcl-2 and bax protein. Tetraarsenic tetrasulfide showed an inhibiting effect on the proliferation of cells ls174t in vitro(P<0.01). It induces the apoptosis of cells ls174t, which is related to the decrease in the expression of bcl-2 and the increase in the expression of bax.

Characterization of a Novel Mesophilic Bacterial Amylase Secreted by ZW2531-1, a Strain Newly Isolated from Soil

WANG Yang, LI Fan, GAO Chao-hui , ZHANG Ying-Jiu

2009, 25(2):  198-202.  doi:

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A novel mesophilic bacterial amylase, named oligosaccharide-producing multifunctional amylase(OPMA), was discovered and characterized. OPMA is an extracellular enzyme secreted by ZW2531-1, a strain newly isolated from Chinese soil. It could be purified to homogeneity from the culture supernatant of ZW2531-1 by 30%―60% saturated ammonium sulfate precipitation, followed by twice Sephadex gel filtration chromatography. OPMA is a 66 kDa protein based on SDS-PAGE and has an isoelectric point(pI) at pH=5.3 by Isoelectric focusing electrophoresis(IFE). It only catalyzes the degradation of starch, rather than other alpha-1,4- and/or 1,6-glucan polysaccharides such as β-cyclomaltodextrin and pullulan. OPMA degraded starch to produce several oligosccharides including maltose, maltotriose, and isomaltotriose as the major end-products, and perhaps other oligosaccharides such as isomaltotetraose, rather than glucose. OPMA exhibited optimal catalytic activity at a reaction temperature of 50 °C and pH=6.0, as determined by orthogonal test. Under the optimal reaction conditions, purified OPMA had a specific activity of 13.75 U/mg. These findings suggest that OPMA could be used for the production of some oligosaccharides beneficial to the food industry and medicine.

Construction of Multi-ribozyme Expression System and Its Characterization of Cleavage on the MDR1/MRP1 Double Target Substrate in vitro

TIAN Sheng-li , ZHENG Suo , LIU Shi-de , ZHANG Jian-hua , XU Dong-ping , OHNUMA Takao

2009, 25(2):  203-210.  doi:

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To improve catalytic activity of ribozyme on its substrate, the multi-ribozyme expression system was designed and constructed from 20 cis-acting hammerhead ribozymes undergoing self-cleavage with 10 trans-acting hammerhead ribozymes inserted alternatively regularly and the plasmid of pGEM-MDR1/MRP1 used to transcribe the MDR1/MRP1(196/210) substrate containing double target sites was also constructed by DNA recombination. Endonuclease digestion analysis and DNA sequencing indicate all the recombinant plasmids were correct. The cleavage activities were evaluated for the multi-ribozyme expression system on the MDR1/MRP1 substrate in the cell free system. The results demonstrate that the cis-acting hammerhead ribozymes in the multi-ribozyme expression system were able to cleave themselves and the 72 nt of 196Rz and the 71 nt of 210Rz trans-acting hammerhead ribozymes were liberated effectively, and the trans-acting hammerhead ribozymes released were able to act on the MDR1/MRP1 double target RNA substrate and cleave the target RNA at specific sites effectively. The multi- ribozyme expression system of the [Coat'A196Rz/Coat'B210Rz]₅ is more significantly superior to that of the [Coat'A196Rz/Coat'B210Rz]₁ in cleavage of RNA substrate. The fractions cleaved by [Coat'A196Rz/Coat'B210Rz]₅ on the MDR1/MRP1 substrate for 8 h at observed temperatures showed no marked difference. The studies of Mg²⁺ on cleavage efficiency indicate that cleavage reaction is dependent on Mg²⁺ ions concentration. The plot of lg(k_obs) vs. lgc(Mg²⁺) displays a linear relationship between 2.5 mmol/L and 20 mmol/L Mg²⁺ . It suggests that Mg²⁺ ions play a crucial role in multi-ribozyme cleavage on the substrate.

Inhibitory Effects of Polygoni Multiflori Caulis Extracts on Matrix Metalloproteinase Activities

LIU Jun-song,5 , YANG Jin-gang , HONG Yuan , JIN Feng-hai , WANG Ming-cui , ZHAO Shu-hua , FANG Xue-xun

2009, 25(2):  211-215.  doi:

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Matrix metalloproteinases(MMPs) play an essential role in development and tissue remodeling of living organisms. However, the overexpression of MMPs has lead to a series of diseases, such as cancer, arthritis, and atherosclerosis; and inhibition of MMPs may have therapeutic benefits. The discovery of MMP inhibitors from herbal has become a prospective event. We showed that the extract of Polygoni multiflori caulis from ethyl acetate or water(ethyl acetate extract and water extract) can inhibit the activities of MMPs 9, 14, and 16 in a dose-dependent manner and n-butyl alcohol extract of it can also inhibit these MMPs. Furthermore, we found that n-butyl alcohol extract and water extract of it influence the cell viability. These discoveries may contribute to the development of MMP inhibitors for the therapy of a variety of pathological conditions.

Antioxidant Effect of Human Selenium-containing Single-chain Fv in Rat Cardiac Myocytes

HUO Rui, SHI Yi, XU Jun-jie, YAN Fei, LU Shao-wu, SU Jia-ming, DUAN Yu-jing, FAN Jia, NING Bo, CONG Deng-li, YAN Gang-lin, LUO Gui-min , WEI Jing-yan

2009, 25(2):  216-219.  doi:

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Reactive oxygen species(ROS) plays a key role in human heart diseases. Glutathione peroxidase(GPX) functions as an antioxidant as it catalyzes the reduction of hydroperoxide. In order to investigate the antioxidant effect of human selenium-containing single-chain Fv(Se-scFv-B3), a new mimic of GPX, a model system of hydrogen peroxide(H₂O₂)-induced rat cardiac myocyte damage was established. The cardiac myocyte damage was characterized in terms of cell viability, lipid peroxidation, cell membrane integrity, and intracellular H₂O₂ level. The Se-scFv-B3 significantly reduced H₂O₂-induced cell damage as shown by the increase of cell viability, the decline of malondialdehyde(MDA) production, lactate dehydrogenase(LDH) release, and intracellular H₂O₂ level. So Se-scFv- B3 may have a great potential in the treatment of human heart diseases induced by ROS.

Activation of CFTR-mediated Cl^– Transport by Capsaicinoids in Cell Culture Model

ZHAO Xue-liang , HOU Ting-ting , GE Hong , SUN Juan-juan , YANG Hong , MA Tong-hui

2009, 25(2):  220-223.  doi:

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Previous studies reported that capsaicin potentiates ΔF508 mutant cystic fibrosis transmembrane conductance regulator(CFTR) channel gating defect by transfected cell-based assays. It has been postulated that orally ingested capsaicin may conceptually be used to develop a therapeutic strategy to treat gastrointestinal disorders in CF patients. We tried to reproduce and extend those pre-clinical data of previous studies. Cell-based fluorescence functional measurements in Fischer thyroid epithelial cells(FRT) expressing CFTR showed no effect of capsaicin on potentiating ΔF508-CFTR, while genistein showed a strongly positive activity. Studies show that capsaicin and dihydrocapsaicin activated cAMP-prestimulated wild-type CFTR in a dose-dependent manner with a maximal response of 70% of that activated by genistein, thus gave an apparent EC₅₀ of (40.4±6.8) µmol/L and (150.2±7.4) µmol/L respectively. Preliminary study shows that the binding sites for capsaicin and dihydrocapsaicin may be probably partially overlapped with that for genistein because the maximal activation of wild-type CFTR with genistein is partially blocked by capsaicin and dihydrocapsaicin.

Efficiency and Mechanism of Phosphorus Removal by Coagulation of Iron-manganese Composited Oxide

YANG Yan-ling , LI Xing, GUO Can-xiong , ZHAO Fu-wang , JIA Feng

2009, 25(2):  224-227.  doi:

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Iron-manganese composited oxide(FeMnO) was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficiency and pollution removal mechanism of the FeMnO were approached. Results show that the main compositions of the FeMnO are δ-manganese dioxide and ferric hydroxide. The specific surface area is about 146.22 m²/g. The FeMnO contains rich hydroxyl with extremely strong adsorption action and chemical adsorption activity. The zero charge point of the oxide in pure water is about 8.0 of pH value. Under neutral pH value conditions, the FeMnO particle surface carried positive charges. The FeMnO particles are quasi-spherical micro-particles with irregular sizes adjoined each other to form net construction. Phosphorus removal efficiency of the FeMnO is remarkable, the total dissoluble phosphorus of settled water can be reduced below detecting level(0.3 µg/L) at a FeMnO dosage of 6 mg/L, and total phosphorus below detecting level at a FeMnO dosage of 10 mg/L, for water samples containing total phosphorus of 1281.70 µg/L and total dissoluble phosphorus of 1187.91 µg/L. The mechanism of effective coagulation for phosphorus removal is combined results of multiple actions of adsorption, charge neutralization, adsorption/bridging and so on.

Mass Spectrometric Studies on Metal-hexafluorobenzene Anionic Complexes(M=Ag, Au, Pd, Pt, Pb and Bi)

SUN Zhang , SUN Shu-tao , LIU Hong-tao , ZHU Qi-he , GAO Zhen , TANG Zi-chao

2009, 25(2):  228-233.  doi:

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The anionic products from the reactions between metal(M=Ag, Au, Pd, Pt, Pb and Bi) vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas(Ar) were studied by means of a homemade reflectron time-of-flight mass spectrometry(RTOF-MS). Experimental results show that the dominant products were [M_mC₆F₆]^– complexes for the reactions of Ag, Au, Pd and Pt with C₆F₆, while the dominant products were [M_mC₆F₅]^– complexes for the reactions of Pb and Bi with C₆F₆. The formation mechanisms of the products, including the adsorption of me- tal cluster anions on hexafluorobenzene and the C―F cleavage induced by metal cluster anions, were discussed.

Pyrolysis of Glucose over Two Amphoteric Metal Oxides

YANG Yu, XIANG Xi, LUO Jia, QI Wei-Yan, YAN Hong-Peng, LI Gui-Ying, HU Chang-Wei

2009, 25(2):  234-238.  doi:

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The catalytic pyrolysis of glucose over amphoteric metal oxide, ZnO or γ-Al₂O₃, was studied comparatively with direct pyrolysis. The effects of catalyst to glucose ratio on the yields of pyrolytic products and on the chemical composition of the liquid products were discussed. Compared with the pyrolytic products of direct pyrolysis, the amount of residual char decreased, whereas the gas yield increased in the presence of the catalysts. The highest liquid yield over ZnO(49.5%) was obtained when the ratio of ZnO to glucose was 5%, whereas over γ-Al₂O₃ the liquid yield increased with increasing the amount of γ-Al₂O₃ added. The presence of both the catalysts enhanced the selectivity to furans in liquid and reduced that of anhydro sugars. A selectivity of 69.7% to furans was obtained over 1% ZnO with a selectivity of 14.6% to 5-hydroxymethylfurfural(HMF). The maximum selectivity to furans(74.9%) and that to HMF(25.6%) were obtained in the presence of 10% γ-Al₂O₃.

Preparation of Ultrafine and High Dispersion Pd/C Catalyst and Its Electrocatalytic Performance for Formic Acid Oxidation

TANG Ya-wen , ZHANG Lin-lin , WANG Xin , BAO Jian-chun , ZHOU Yi-ming , LU Lu-de , LU Tian-hong,

2009, 25(2):  239-242.  doi:

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A carbon supported Pd(Pd/C) catalyst used as the anodic catalyst in the direct formic acid fuel cells(DFAFC) was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate(EDTA) as stabilizer and complexing agent. This method is very simple. The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity. The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.

Bonding Characteristics and Magnetic Coupling Interactions in One-dimensional α'-NaV₂O₅

FAN Hou-gang , MING Xing , HU Fang , WANG Chun-zhong , HUANG Zu-fei, , CHEN Gang

2009, 25(2):  243-246.  doi:

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The spin-polarized generalized gradient approximation(GGA)+U approach was employed to study the bonding characteristics and magnetic coupling interactions in room-temperature phase α'-NaV₂O₅. The calculated results indicate that the V_dxy orbital is split off from other 3d orbitals in the VO₅ pyramidal ligand field. The V_dxy orbitals are hybridized strongly with the O_px/py orbitals, forming a V―O―V π bond in the ab plane. The ligand field effect together with the intra-atomic exchange splitting results in the insulating behavior. With the aid of Noodleman's broken symmetry methods, the magnetic exchange constant was derived from mapping the relative energies onto the Heisenberg model. The antiferromagnetic(AFM) exchange energy, J, along the chain was calculated to be –593 K in good agreement with the experimental data.

DFT Predictions on Structures and Stabilities of Eleven-vertex nido- and closo-Heteroboranes

LI Ping

2009, 25(2):  247-256.  doi:

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Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31+G(3d,2p) level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B―Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B―Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configurations. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.

Infrared Spectroscopic Investigations of J-aggregates of Protonated Tetraphenylporphine

ZHOU Mi, LU Guo-hui, GAO Shu-qin , LI Zuo-wei

2009, 25(2):  257-260.  doi:

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Protonated tetraphenylporphine(H₂TPP) J-aggregates were prepared by aggregation on the liquid-air interface. Using FTIR spectroscopy, the authors observed the infrared absorption spectra of H₂TPP and its J-aggregates. The IR spectra of H₂TPP J-aggregates show significant changes compared with that of H₂TPP monomer. Intensity changes(e.g., strong enhancement of the in-plane vibronic mode and weakening of the out-of-plane vibronic mode of phenyl and porphyrin skeletal) were interpreted on the basis of stacking effects. Observation of the same type of bands collapse into single band was explained by the increase in the symmetry of H₂TPP molecules. And the new bands at 1635 and 3407 cm^–1 indicate the aggregates containing a large amount of bound water.

Research Note

Synthesis of Poly(aryl ether ketone) Copolymers Containing Adamantyl-substituted Naphthalene Rings

ZHU Xiao-liang, ZHANG Shu-ling, REN Dian-fu, GUAN Shao-wei, WANG Gui-bin , JIANG Zhen-hua

2009, 25(2):  261-264.  doi:

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In order to acquire more significant modification on the properties of PAEKs, we attempt to introduce more adamantyl groups into one repeated unit of the polymer chain. Hereby, naphthalene rings were chosen to synthesize novel monomer so that it can afford more reaction active points for adamantyl groups substituting. Herein, we successfully synthesized double adamantyl-substituted aromatic bisphenol monomer, 4,8-bis(1-adamantly)-1,5-dihydroxynaph- thalene(AdNp) via the Friedel-Crafts reaction, and synthesized new PAEKs containing adamantyl groups(Ad-PAENKs) based on the new monomers of AdNp, (3-trifluoromethyl)phenyl hydroquinone(3FHQ) and 4,4'-difluorobenzophenone(DFB) via the nucleophilic aromatic substitution polymerization. The structure and basic properties of Ad-PAENKs were characterized by several analysis methods.