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    24 February 2001, Volume 22 Issue 2
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    Articles
    Synthesis and Crystal Structure of A Novel One-dimensional Cyano-bridged Chain Complex [Eu(DMF)4·(H2O)2Mn(CN)6·H2O] n
    YAN Bing, WANG Shi Xi, CHEN Zhi Da
    2001, 22(2):  167-170. 
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    Using K3Mn(CN)6, N,N-dimethylformamide(DMF) and Eu(NO3)3·6H2Oas reactants, a novel one dimensional cyano bridged chain complex [Eu(DMF)4·(H2O)2Mn(CN)6·H2O]n has been first synthesized and characterized with elemental analysis, IR, UVspectra and X-ray crystal analysis. The complex crystallizes in the monoclinic P21/c space group, with lattice parameters a =1.2992(3) nm, b =1.2764(3) nm, c =1.9154(4) nm, β =109.42(3)°, V =2.9956(12) nm3, Dx=1.573 Mg/m3, Z =4, R =0.0372, Rw=0.0962, GOF=1.095. The complex shows one dimensional chain structure due to the two bridging CNbetween Eu and Mn atom.
    In-situ Electrochemical Synthesis of the Metalloporphyrins with the Help of the Voltammetry of Immobilized Microparticles
    ZHUANG Qian Kun, Fritz Scholz
    2001, 22(2):  171-174. 
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    Upon cyclic electrochemical polarization, traces of 5,10,15,20-tetraphenyl-21H,23H-porphyrin(H2TPP), which have been mechanically transferred to the surface of a paraffin-impregnated graphite electrode, can incorporate copper, iron or cobalt ions from aqueous solution into the porphyrin ring to form CuTPP, FeTPPCl and CoTPPCl. The binding of metal ions by H2TPPcan be studied by voltammetry of immobilized microparticles. The mechanism of formation and reaction of the metalloporphyrins and their electrocatalytic properties were elucidated.
    The Influence of Al Doping on the Structure of Li(AlyCo1-y)O2 Materials
    HAO Wan Jun, CHEN Gang, SHI Yan Hui
    2001, 22(2):  175-178. 
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    X-ray diffraction for Li(Aly Co1-y )O2 was carried out for different values of y(y =0, 0.1—1). The structural evolution of the material with y was revealed. It is shown that material is in single layered phase for y ≤0.5; in double phases [Li(Aly Co1-y )O2 and γ-LiAlO2] for 0.6≤ y ≤0.9 and single [ γ-LiAlO2] phase for y =1. The highest solubility for the Al doping is about 50%. Lattice constant a decreases, and lattice constant c increases, respectively, within the region of Al doping for y ≤0.5.
    A Novel Method for Preparation of Silicalite-1 Zeolite Membrane in Vapor Phase
    LI Jun, LONG Ying Cai
    2001, 22(2):  179-181. 
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    Asilicalite 1 zeolite membrane was in situ crystallized from a layer of silica species prepared by a novel method of low temperature chemical vapor deposition (LTCVD) on a porous cordierite substrate. XRDpatterns show that the membrane consists of MFItype zeolite crystals. The investigation with SEMindicats that the membrane is about 50 μm thick, and covered with well intergrowth MFIzeolite crystals of about 10 μm in size. The EDXanalysis confirms that the membrane is composed of silica in the absence of Al, indicating high silica MFI(Silicalite-1) zeolite grown on the support. The ratio of pure gas permeation is 296 for H2/ iso butane and 13.7 for n / iso butane at room temperature respectively, confirming that the membrane synthesized on the support of cordierite is high quality without pinhole.
    Synthesis and Spectral Properties of the Complexes of Lanthanide Nitrates with 1,1,1-Tri-[1'-(2'-oxa-5'-oxo-6'-aza6'-bisphenyl)hexyl] Propane
    TAI Xi Shi, TAN Min Yu, LIU Wei Sheng
    2001, 22(2):  182-184. 
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    Atripod ligand, 1,1,1-tri-[1'-(2'-oxa-5'-oxo-6'-aza-6'-bisphenyl)hexyl] propane(L), and its complexes with Ln(NO3)3 · n H2O(where Ln=La, Ce, Pr, Nd) have been synthesized. These new complexes with the general formula of Ln2L(NO3)6· n H2O(where Ln=La, n =4; Ln=Pr, n =2; Ln=Ce, Nd, n =1) were characterized by elemental analysis, IRspectra, thermal analysis, 1H NMRspectra and molar conductivity. All the complexes are stable in air and their conductances in acetonitrile solution lie in the 149—158 S·cm2·mol-1 range, indicating that they are 1∶1 type electrolytes. The IRand 1H NMRspectra of the ligand and its complexes show that all the ether oxygen atoms and the COgroups take part in coordination to the metal ions, and the larger shift for νC=Oin the IRspectra of the complexes suggests that the Ln—O(carbonyl) bond is stronger than the Ln—O(ether) one which also was inferred from the 1H NMRspectral data. The thermal behaviour of the complexes are similar. The first loss occurs at 85—100.9 ℃ corresponding to the loss of all the water molecules. The weight losses found in this process compare favourably with the theoretical values. Moreover, the relatively low temperatures of dehydration are consistent with the presence of crystal water.
    Synthesis and Characterization for Complexesη2-C70[RhCl(CO)(PPh3)2]n
    YANG Sen-Gen, TANG Tian, LIN Yong-Sheng, CHENG Da-Dian, ZHAN Meng-Xiong, ZHENG Lan-Sun
    2001, 22(2):  185-187. 
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    The fullerene complexes, η2-C7Ox[RhCl(CO)(PPh3)2]n(n=1, 2), have been prepared by the reaction of C70 with RhCl(CO)(PPh3)2 in methylbenzene at room temperature. The new complexes were characterized by UV-Vis spectra, IR, XPSand elemental analysis. The results show that the complexes of η2 form can be formed by RhCl(CO)(PPh3)2 bonding to C70 in theσ-π way. In addition, the complexes structures have been supposed.
    Crystal Structure, Stacking Effect and2D Network Assembled by Hydrogen Bonds of Quaternary Complex [Ce(CH2ClCOO)2(NO3)(phen)(H2O)]2
    ZHU Long-Guan, Susumu Kitagawa
    2001, 22(2):  188-190. 
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    The quaternary complex, [Ce(CH2ClCOO)2(NO3)(phen)(H2O)]2, was synthesized. Interestedly, the title compound is a dimer comparing with the 1Dpolymer [La(CH2ClCOO)2(NO3)(phen)·(H2O)]n and powder compound [Nd(CH2ClCOO)2(NO3)(phen)]. In the title compound there is a monodentate NO3-, which is a first example in the all synthesized quaternary mixed anion complexes, and the NO3- extended the complex into a 2Dnetwork with water from other molecules by inter-molecular hydrogen bonds. The intermolecular hydrogen bonds lead to the weaker Ce—O(COO), Ce—O(NO3) and Ce—Nbonds comparing with other quaternary mixed anion complexes of cerium. Also the stacking effect, which makes the compound more stable in the situation of weaker Ce—Oand Ce—Nbonds, was first found in the series compounds.
    A Lithium Ion-selective Optical Chemical Sensor Based on the Inner-filter Effect of Fluorescence
    ZHONG Jing-Rong, LIU Miao-Gen, AO Bing-Yun, YANG Xiao-Hai, WANG Ke-Min, XIAO Dan
    2001, 22(2):  191-196. 
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    In this paper, an optical chemical sensor of fluorescence enhancement for lithium ion has been developed on the basis of ion-exchange sensing scheme. Asuitable fluorescent agent is incorporated in the plasticized PVCmembrane containing a lipophilic pH-indicator and lithium-selective neutral ionophore. Fluorescence varies as a function of the varying absorption of the pH-indicator, which in turn is modulated by the lithium concentration through the inner-filter effect of fluorescence. The response performance of the sensors and their theoretical response equations are reported. At pH9 0, the fluorescence response of the excellent sensor shows a good correlation with the theoretically derived formula in the linear range from 50×10-4 to 50×10-1 mol/Lwith a detection limit of 50×10-5 mol/Llithium ion. The response time is about 1 min.
    Construction of Montmorillonite-modified Carbon Fiber Electrode and ItsIn-vivo Detection of Neurotransmitter
    YANG Li-Ju, PENG Tu-Zhi
    2001, 22(2):  197-200. 
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    The construction of montmorillonite-modified carbon fiber electrode is reported. The modified electrode shows a good sensitivity and selectivity due to its accumulation to cations and inhabitation to anions. The detection limit of DAand 5-HTare 16×10-8 and 1×10-7 mol/L, respectively, which are more sensitive than Nafion modified electrode.In-vivo voltammetry, the electrode has directly detected the dramatic variation of DAconcentration in a rat brain with decreasing blood supply, while it effectively inhabits the oxidation of electroactive compounds and some neurotransmitter metabolites, such as AA, DOPAC, 5-HIAA.
    A Study of the Coupling Position of the Microwave Plasma Torch
    ZHAO Li-Wei, FU Yao, SONG Da-Qian, ZHANG Han-Qi, JIN Qin-Han
    2001, 22(2):  201-205. 
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    The microwave plasma torch(MPT) possesses a configuration with three concentric metal tubes. The microwave energy is coupled into the plasmavia a cylindrical antenna that surrounds the intermediate tube. The effects of the antenna position on MPTdischarge and performance of the plasma were studied. An end-on viewed MPTwas used in this research, and a pneumatic nebulizer was used for sampling. Four emission lines of Ar were studied to find the effect of the coupling position on the plasma background emission. At the same time, the signal intensities and the signal-background ratios of three elements(Al, Mg and V) were also studied, and RSDwas investigated also. From the research, it could be found that the analytical performance was better when the antenna position wasλ/4 than 3λ/4, except of a little poorer repeatability. The structure of electromagnetic field of the MPTwas discussed also.
    Scanning Electrochemical Microscopy Study of Electron Transfer Across the Water/1,2-Dichloroethane Interface Induced by Common Ions
    ZHANG Zhi-Quan, TONG Yue-Hong, SUN Peng, SHAO Yuan-Hua
    2001, 22(2):  206-211. 
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    In this work, we report the reverse electron transfer reaction between TCNQ in 1,2-dichloroethane(DCE) and ferrocyanide in water. This process is a thermodynamic unfavorable reaction and the reverse electron transfer reaction can only be obtained by scanning electrochemical microscopy(SECM) in the presence of suitable potential-determining ions, which govern the interfacial potential difference. In our case, the potential determining ions are tetrabutylammonium ion(TBA+) and tetraphenylarsonium ion(TPAs+). The effects of the concentrations of TBA+ and TPAs+ in two phases and other parameters have been studied in detail. The apparent heterogeneous rate constants(kf) were obtained under different values of Kp(Kp=ciw/cio) for both cases by fitting the SECMapproach curves with theoretical ones and the results showed that they were controlled by the interfacial potential differences. The relationship between apparent heterogeneous rate constants and the interfacial potential differences obeys Butler-Volmer theory.
    The Algorithm on Ring Perception of Molecule
    HAO Jun-Feng, XU Lu
    2001, 22(2):  212-214. 
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    It's important to identify ring in the process of structure elucidation. In this paper, all rings and the smallest set of smallest ring(SSSR) of structure are obtained from two-dimensional connection table. The results are satisfactory by using this algorithm in ESESOCexpert system as constraint.
    Plant Tissue-based Chemiluminescence Flow Biosensor for the Determination of Oxalate
    PENG You-Yuan, QIN Wei, ZHANG Zhu-Jun
    2001, 22(2):  215-217. 
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    Anovel chemiluminescence(CL) biosensor for the determination of oxalate is presented in this paper. It is based on the CLreaction between luminol, immobilized on an anion-exchange column, and hydrogen peroxide generated on-linevia oxalate by the catalytic effect of oxalate oxidase in spinach in the flow cell. The biosensor responds linearly to oxalate concentration in the range of 4.0×10-7 to 1.0×10-4 mol/L, and the detection limit is 2×10-7 mol/L. Acomplete analysis could be performed in 1 min with a relative standard deviation of 3.7% for 1.0×10-5 mol/Loxalate(n=7). The system is stable for over 200 times determinations and has been applied in urine samples.
    Molecular Recognition Study ofβ-Cyclodextrin and Its Two Derivatives with Some Aliphatic Guests by Competitive Inclusion Method
    YOU Chang-Cheng, ZHAO Yan-Li, LIU Yu
    2001, 22(2):  218-222. 
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    Spectrophotometric titrations were performed in aqueous buffer solution(pH=10.5, c=0.025 mol/L) at 25 ℃ to determine the binding constants ofβ-cyclodextrin(β-CD), mono(6-O-α-maltosyl)-β-cyclodextrin(6-G2-β-CD) and mono[2-O-(2-hydroxypropyl)]-β-cyclodextrin(2-HP-β-CD) with several aliphatic chiral guest molecules using phenolphthalein as a spectral probe. The results obtained indicate that several weak interactions cooperatively contribute to the inclusion complexation of theβ-cyclodextrin hosts and the complex stability is dominated by the size/shape-matching between host and guest. The substituent on the cyclodextrin derivatives changes its original binding ability. For the relatively small guest molecules,i.e., borneol, camphor and menthol, the molecular binding ability is 2-HP-β-CD>β-CD>6-G2-β-CD. Furthermore, the threeβ-cyclodextrin hosts can also serve as chiral discrimination reagents and afford stronger binding ability toward (+)-isomers. Among them, 2-HP-β-CDgives a moderate enantiometric selectivity of 1.25 for (+)/(-)-camphor.
    A Study of Asymmetric Baeyer-Villiger Reaction of 2-Phenylcyclohexanone Catalyzed by Chiral Salen-Cu(Ⅱ) and Oxazoline-Cu(Ⅱ) Complexes
    PENG Yun-Gui, FENG Xiao-Ming, WANG Bin, LI Zhi, YANG Gui-Shu, JIANG Yao-Zhong
    2001, 22(2):  223-227. 
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    In this paper, we have studied the asymmetric Baeyer-Villiger reaction of 2-phenylcyclohexanone catalyzed by Cu(Ⅱ) complexes which derived from a series of chiral Salen and oxazoline ligands, as well as designed and synthesized the new chiral ligands Ⅲ, Ⅳ, Ⅴ. And the configuration of complex Ⅴ-Cu(Ⅱ) was determined by X-ray analysis. We also investigated the influence of co-oxidant, solvent, etc. on the reactivity and selectivity.
    Asymmetric Synthesis of Methyl3β-Hydroxyeudesmane-4,11(13)-dien-12-oicate
    ZANG Zhe, ZHOU Gang, GAO Xiao-Lei, LI Yu-Lin
    2001, 22(2):  228-229. 
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    Afacile and efficient diastereoselective synthesis of methyl 3β-hydroxyeudesmane-4,11(13)-dien-12-oicate starting from (+)-dihydrocarvone has been carried out in 9 steps at the first time.
    Adsorption of Some Aromatic Compounds in ITQ-1 Zeolite: Grand Canonical Monte Carlo Simulations
    HOU Ting-Jun, ZHU Li-Li, XU Xiao-Jie, JI Ming-Juan, YE Xue-Qi
    2001, 22(2):  230-233. 
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    The sdsorption behavior of benzene, toluene andm-xylene in ITQ-1 zeolite has been studied by using grand canonical Monte Carlo (GCMC) simulations. The mass clouds of the studied sorbate molecules indicate that the diffusion and adsorption of sorbate molecules mainly occur in 12-MWcavities, while the diffusion and migration in 10-MRchannels seem to be more difficult. Aseries of calculations have been performed to predict the adsorption isotherms of those molecules at 315 Kand 0—1.4 kPa, and the results coincide well with the results from experiments of a series of aromatic compounds. The GCMCsimulations and experimental results reveal that at a certain pressure and temperature, all the studied molecules can migrate through 10-MRchannels and 10-MRwindows systems interconnecting 12-MRsupercages and reach the adsorption equilibrium.
    Studies on Pyrolysis Properties and Kinetics of Carbon Matrix Precursor CH3ArCH2NH2
    WANG Hui, YANG Hai-Feng, LUO Rui-Ying, YANG Yan-Qing, RAN Xin-Quan
    2001, 22(2):  234-239. 
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    Pyrolysis behavior of carbon matrix precursor CH3ArCH2NH2 used for preparing C/Ccomposites by rapid densification process was investigated by closed-pressure-vessel method, DSC, high-pressure DSCmethods and ultraviolet spectrophotometric method. The pyrolysis temperatures and carbon residual ratios of the compound at different temperatures and different pressures were derived and the apparent activation energy was also obtained by isothermal dynamic and non-isothermal dynamic method. The experimental results are as follows: at the atmospheric pressure, the pyrolytic temperature is about 530.15—547.15 K; at the pressure as high as 1—3 MPa, the pyrolytic temperature is about 618.34—675.49 K. The carbon residual ratios in the closed pressure vessel, at the atmospheric pressure and at a high pressure are 56.23%, 28.96%—36.47% and 59.11% respectively. Based on Kissinger's method and the result of isothermal experiment, the apparent activation energies of the pyrolysis reaction under the isothermal and non-isothermal conditions are 206.78 kJ/mol and 183.93 kJ/mol respectively, and the reaction order n≈1.
    Interaction Parameters of the Excess Gibbs Free Energy Between Saccharides and Non-electrolytes in Formamide
    TANG Qing-Hu, BAI Tong-Chun, LU Yan, ZHAO Pei-Zhen, LU Jin-Suo
    2001, 22(2):  240-244. 
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    The retention values of ten non-electroltyes in stationary solution of formamide-glucose, formamide-fructose and formamide-sucrose at 298.15 Kwere measured by a gas-liquid chromatographic method(GLC). Depending on the McMillan-Mayer theory, the values of pair and triplet interaction parameters gij andgijj of saccharides with non-electroltyes have been evaluted. The group interaction Gibbs free energy parametersGx,y were evaluted by the Okamoto-Wood group additivity method. The information about the solute-solute interaction and the effect of solvent were discussed.
    Spectral Studies of H-Aggregate of D-π-A Molecule
    CHEN Si-Guang, JIANG Yue-Shun, LU Ran, YANG Wen-Sheng, YANG JI-Hua, LI Tie-Jin, DU Zu-Liang
    2001, 22(2):  245-248. 
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    D-π-Amolecules bearing strong electron donor and acceptor, 5-(4-N,N-dimethyl amino-benzylidene)-(1H,3H)-2,4,6-pyrimidinetrione(AB1) and 5-(4-N,N-dioctadecylaminobenzylidene)-(1H,3H)-2,4,6-pyrimidinetrione(AB18) were synthesized and their spectral properties were investigated. For AB1 and AB18, their UV-visible absorption spectra in cyclohexane and surface photovoltage spectra show peaks at 450 nm due to the formation of H-aggregate, which underwent a blue-shift about 30 nm than that of monomer intramolecular charge transfer(ICT) band in chloroform. The fluorescence emission band of excimer of H-aggregate in solid and at a high concentration in chloroform solution occurs at 620 nm and near 610 nm, respectively. The band at 620 nm underwent a red-shift about 3000 cm-1 than that of monomer. In addition, intermolecularπ-π interactions of such D-π-Amolecules possesing strong electron donor and acceptor are discussed.
    A Quantum-Chemical Study on Structures and Properties of CHMI/MMA Copolymer
    ZHAN Gui-Ling, DAI Bai-Qing, WEI Yong-De, DONG Shao-Sheng
    2001, 22(2):  249-251. 
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    Ab initio calculations are carried out for the CHMI/MMAcopolymer unit. The calculated results of internal rotation energy barriers, bond energies, Mulliken populations and free volumes suggested that these parameters of CHMI/MMAcopolymer had higher values than that of PMMA, and the conclusions are in consistence with experimental results.
    Theoretical Study of the Complexes of First-row Transition Metals with SiH2
    LI Ji-Hai, GAO Jian-Jun, FENG Da-Cheng, FENG Sheng-Yu
    2001, 22(2):  252-256. 
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    The HF/6-311+G*basis set was used to study the characteristics of molecular orbitals and bond dissociation energies of the complexes, MSiH2, of the first-row transition metals with SiH2. The atoms in MSiH2 are all coplanar, and M—Si bonds of ground state 3TiSiH2 and 4CoSiH2 show obviously the double bond characteristic. In 4VSiH2 and 5CrSiH2 there is the week single occupiedπ bond. The 8MnSiH2 with a high-spin eightet ground state has both of single occupiedσ andπ bonds, and chief component of itsσ andπ orbital are the Mn4s and the Si 3px orbitals, respectively. Other ground state MSiH2 have only a double occupiedσ single bond. The most of M—Si bonds are quite covalent. The formation of M—Siσ bonds can be considered as the interaction between one electron in4s or 4pz, or 3d orbital of Mand other electron in Sisp hybrid orbital. The double occupiedπ bonds are also considered as the pairing of oneπ electron of SiH2(3B1) with one 3d electron of M. All of the HSiHbond angles in MSiH2 are closed to that in SiH2(3B1). It means that the Si in MSiH2 still keeps asp hybrid orbital similar to Si in SiH2(3B1 states). The Sc—Si, V—Si and Ni—Si bonds are longer because their formation involves mainly the 4s orbitals of M. On the contrary, the Cu—Si bond is shorter since itsσ bond would involve primarily the M 3dZ2 obitals. The 3TiSiH2 and 4CoSiH2 have much shorter bond lengths and larger bond dissociation energies because of their double bond character. From Sc to Cu, the bond dissociation energies of M—Si change in periodic trend. There is an approximate linear relationship between the bond dissociation energies and the metal ion promotion energy.
    Electron Correlation Effects in the Hyperpolarizabilities of Five-membered Heterocyclics
    WANG Xu, YANG Ming-Li, SUN Ze-Min
    2001, 22(2):  257-261. 
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    The dipole moments, polarizability, first- and second-order hperpolarizabities of pyrrole, furan and thiophene have been calculated by finite-field method at Hartree-Fork and Mller-Plesset levels, respectively. The calculation shows that electron correlation effects have considerable influences on the polarizability at all orders, in particular the high-order ones. The MP2 calculation improves the results remarkably at H-Flevel. The first-order hyperpolarizabilities increase in the order of MP2, MP3 and MP4, while the second-order hyperpolarizabilities at MP2 level are similar to those at MP4 level and are larger than those at MP3 level. The same relative order of the all-order polarizability is found between H-Flevel and different orders of Mller-Plesset method.
    Theoretical Study on Chiral Amino Acid Recognition by Zinc(Ⅱ) Porphyrin
    WANG Chuan-Zhong, ZHU Zhi-Ang, LI Ying, CHEN Rong-Ti, WEN Xin, MIAO Fang-Ming, CHEN Xin-Zi
    2001, 22(2):  262-264. 
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    The minimal energy conformation of a chiral zinc(Ⅱ) porphyrin was studied by using molecular mechanics method on the basis of Tripos force field. The molecular dynamics simulating was performed to investigate the process of chiral recognition. The result shows that the host molecule prefers to D-amino acid ester, which is consistent with that from the experiment.
    Theoretical Studies on the Mechanism Cycloaddition Reaction of Silylene with C60
    XIA Shu-Wei, SHANG Zhen-Feng, CHEN Lan, PAN Yin-Ming, ZHAO Xue-Zhuang, TANG Au-Chin
    2001, 22(2):  265-271. 
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    The cycloaddition reaction of silylene(SiH2) and C60 have been studied by using the semi-empiri- cal method AM1, a reasonable mechanism of the reaction has been suggested. All the geometry of the sta- tionary points on the reaction path have been optimized by energy gradient technique and the transition states were characterized by vibration frequency analysis. The calculation results show that the reaction mechanism is different between 6-6 and 6-5 bond addition. The 6-6 bond cycloaddition reaction proceedvia two steps: (1) Silylene and C60 form an intermediate complex; (2) The closed isomer of C60SiH2 is formedvia TSfrom intermediate complex. After being corrected by zero-point energies the barriers is 0.45 kJ·mol-1. While the 6-5 cycloaddition reaction is of three steps: (1) An intermediate complex is formed from the reactants C60 and SiH2 with no barrier. (2) The closed intermediate is formedvia TS(Ⅰ). After being corrected by zero-point energies the barriers is 9.19 kJ·mol-1. (3) The opened isomer of C60SiH2 is producedvia TS(Ⅱ) with the barrier of 4.33 kJ·mol-1. The reasons that silylene cycloaddition should take place across 6-6 bond rather than 6-5 bond of C60 are explained from the reaction mechanism and kinetic factors.
    Photocatalytic Degradation of Bromomethane on Sol-gel Derived Titania
    SU Wen-Yue, FU Xian-Zhi, WEI Ke-Mei
    2001, 22(2):  272-275. 
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    The photocatalytic degradation of bromomethane in airstreams was studied over the TiO2 catalysts prepared by sol-gel method. The influence of calcination temperature, reaction temperature, the residual NO3- in catalyst and water vapor on the structure of catalysts and their photocatalytic performance was examined by means of X-ray diffraction technique, N2 sorption analysis with BETmethod, FTIRspectroscopy and photocatalytic activity measurement. The results showed that the photocatalytic decomposition of CH3Br followed first-order kinetics, and the apparent activation energy was determined to be 13.7 kJ/mol. The distinct deactivation of TiO2 catalysts for the photocatalytic oxidation of bromomethane was observed in the initial period of reaction. Some factors such as high calcination temperature, the residual NO3- and water vapor in the feed stream decreased the photocatalytic activity of TiO2 catalysts. However, the reactivity of bromomethane is greatly enhanced at increasing reaction temperatures. The effect of raising reaction temperature has been ascribed to decreasing adsorption of water.
    In Situ FTIR Study of Effect of La on CH3OH Automobile Exhaust Oxidation Mechanism on Supported Palladium Catalyst
    WAN Ying, WANG Xing-Yi, LU Guan-Zhong
    2001, 22(2):  276-279. 
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    The performance of deep oxidation of methanol on 0.1% Pd supported on alumina was studied by a chromatograph-micro-reactor. The results showed that the addition of La intoγ-Al2O3 could affect the performance of Pd catalyst greatly. Although the presence of La could not lower the light-off temperature of methanol oxidation, the partial oxidation products disappeared. By usingin-situ FTIR, it is shown that La changed the adsorbed species and the methanol deep oxidation mechanism on Pd catalyst.
    Synthesis and Characterization of Supported Complex Catalyst Cu2(OAc)2/SiO2──TPD,In situ-IR Study for Synthesis of EC by Activation of CO2 and EO
    GAO Jian, ZHONG Shun-He
    2001, 22(2):  280-284. 
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    Silica supported dinuclear complex catalyst was prepared by SiO2 surface modification and metal anchoring, namely Cu2(OAc)2/SiO2. The chemical composition, bonding fashion of the bridging ligand and coordination environment of the metal ions on the SiO2 surface were characterized by titration method, IRand UV-Vis analysis.The catalyst mode as a whole was given by the illumination of the formation of the catalyst. The absorption properties of catalyst Cu2(OAc)2/SiO2 to molecules CO2 and EO (ethylene oxide) were studied by molecule probing IRand TPDtechniques. Experimental results indicated that the CO2 and EOwere chemisorbed and bridging absorption structures were formed between the two copper (Ⅱ) ions. TPD-MSexperiments established that CO2 and EOdesorbed from the surface of the catalyst at 120 ℃ and 130 ℃ respectively. Catalytic reaction properties for the synthesis of EC (ethylene carbonate) from CO2 and EOwas studied by TPSR-IRon line technique, indicating that the reaction could undertake at 120 ℃ and low pressure.
    Surface Organometallic Chemistry on Zeolite Grafting Reaction of Ge(n-C4H9)x Fragments over ZSM-5 outer Surface and Adsorption Properties of the Resulting Materials
    WANG Xu-Xu, ZHAO Hui-Xia, FU Xian-Zhi, Frédéric LEFEBVRE, Jean-Marie BASSET
    2001, 22(2):  285-288. 
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    The reaction of tetrabutylgermanium with ZSM-5 surface at 230 and 280 ℃ was studied by means of gas volumetry, infrared spectroscopy, solid-state NMRand elemental analysis. The thermal stability and the adsorption properties of the resulting solids were also determined. Acondensation occurred between tetrabutylgermanium and the surface hydroxyl groups of ZSM-5, being closly analogous to what had been observed on silica and mordenite. The products in the gas phase are C1—C4 hydrocarbons formed by cracking of the evolved butane on the highly acidic ZSM-5, and in contrast to the report on silica or mordenite, a mixture of [(≡Si—O)xGe(n-C4H9)x-4)](x=1, 2, 3) species was formed. Increasing the reaction temperature resulted in much more dealkylated species. After heating at 450 ℃, no butyl ligand remained on germanium. No modification of the solid was detected by nitrogen adsorption, showing that the zeolitic structure was retained upon grafting. The modified materials show that the adsorption properties are quite different from those of the starting ZSM-5. For example, 2,3-dimethyl butane is totally excluded from the modified zeolite while the unmodified one easily adsorbs it.n-Hexane and 2-methyl pentane are also discriminated by this zeolite but, in this case, it is due to a decrease of the sorption rate at the pore entrance due to steric hindrances caused by the grafted fragments.
    Influence of Cholesterol on Molecular Ordered Assemble Systems of PC/Cholesterol and Crystal Type of CaCO3
    TONG Hua, YAO Song-Nian, HU Ji-Ming
    2001, 22(2):  289-292. 
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    The CaCO3 were obtained by chemical reaction in different molecular ordered assemble systems of PC/Cholesterol. X-ray diffraction analyses showed that there are three types of CaCO3 in these systems: colloid CaCO3, vaterite, calcite. The cholesterol not only influences the structure of ordered system, but also influences powerfully crystal type of reaction product in these systems.The calcite decreased with the increase of concentration of cholesterol. SEManalyses showed that CaCO3 nanoparticles can be synthesized in PC/ether reverse micell.
    Theoretical Study on One-carbon Unit Transfer Reaction of Imidazolinium to1,2-Diaminobenzene
    KANG Cong-Min, FENG Da-Cheng, CAI Zheng-Ting
    2001, 22(2):  293-295. 
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    One-carbon unit transfer reaction of imidazolinium with 1,2-diaminobenzene has been studied with semi-empirical molecular orbital calculations, PM3. The result shows that there are two ways to complete this reaction because the imidazolinium ring has two different breaking patterns. These two ways both have seven steps, including two proton-migrating steps that limit the rate of the reaction. The structures and energies of the intermediates and transition states have been calculated.
    Characterization of A Sulfided Mo/γ-Al2O3 Catalyst by Low Temperature FTIR Spectroscopy of Adsorbed CO and Its Thiophene HDS Activity
    QI Xing-Yi, XU Chun-Ming, LIU Zhi-Chang, LI Wen-Zhao, XIN Qin
    2001, 22(2):  296-297. 
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    Asulfided Mo/γ-Al2O3 catalyst was characterized by low-temperature FTIRspectroscopy of adsorbed carbon monoxide, with its HDSactivity being investigated with thiophene as a mold substrate. On the basis of the results here, the conclusion may be obtained that the sites for COadsorption should be the active reaction centers of thiophene HDS.
    Rheological Behavior of Metallocene Catalyzed PE and LDPE Blends
    LIU Chen-Yang, LI Yu-Ying, WANG Jin, HE Jia-Song, ZHANG Lin
    2001, 22(2):  298-302. 
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    The rheological behavior was studied for blends of metallocene catalyzed ethylene/1-butene copolymer(mPE) and low density polyethylene(LDPE). Steady-state viscosity and dynamic viscoelasticity were measured by using a DSR-200 rheometer with parallel plate geometry. Non-linear fitting with the modified cross model was conducted successfully. Due to lower molecular weight and narrower molecular weight distribution(Mw/Mn=21),mPEhas a lower sensitivity to shear, shown by a lower zero shear viscosity, higher values of shear rate and shear stress at the transition from Newtonian to non-Newtonian behavior, higher viscosities in shear rate range from 100 s-1 to 102 s-11. Zero shear viscosities of mPE/LDPE 50/50 and 25/75(mass ratio) blends have a large positive deviation from log-additivity rule, due to a decrease of the free volume fraction in these blends. The transition stress and non-Newtonian index decrease with increasing LDPEfraction in blends, which indicate that the blends have high sensitivity to shear and improved processability. The single correlation betweenG' andG" corresponds to the behavior expected for a miscible blend.
    A Study of Stress-Yielding Mechanism of Aged Atactic Polystyrene
    SONG Rui, ZHAO Jun, YANG Juan, LING-HU Xin, GAO Jin-Gui, FAN Qing-Rong
    2001, 22(2):  303-306. 
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    The stess yielding mechanism of aged atactic polystyrene(α-PS) was studied by use of mechanical tension, differential scanning calorimetry(DSC) and solvent-swelling. The viewpoint of cohensional entaglement(CE) was empolyed to interpret the experimental results, which indicated that the stress yielding of aged α-PSwas the destruction of the CEformed during aging. CEwas a kind of ordered structure, which was formed by local parallel alignment of several segments of several nearest neighboring chains. Its interaction energy was so low that heating beyond theTg region, mechanical drawing over the yield point and solvent swelling all could destroy it completely.
    Synthesis and Characterization of Side Chain Liquid Crystal M5MPP/MMEANB Copolymers Containing NLO Active Group
    FAN Guang-Yu, ZHAO Xiao-Guang, ZHOU En-Le, TIAN Yan-Qing
    2001, 22(2):  307-311. 
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    Anew series of side chain liquid crystal polymers based on the backbone of polymethacrylate containing 4-nitroazobenzene and 4-methoxybiphenyl group as side chain mesogen were prepared and characterized, FTIR, 1H NMR, POMand WAXDwere used to study the structure, phase behavior and mesophase texture of this series of SCLCcopolymers. The researches show that polymer PM5MPPand copolymer M5MPP/MMEANBare enantiotropic liquid crystalline polymers, but polymer PMMEANBhas no liquid crystalline properties. DSCresults showed that the thermal stability of the mesophase of this series of copolymers was enhanced by the existence of intermolecular electron donor-acceptor interaction. It was found that the temperature range of the mesophase of the copolymers was broadened with increasing 4-nitroazobenzene units. The focal-conic texture observed by POMindicated that this series of the copolymers possessed the characteristics of smectic liquid crystal.
    Mechanism of Forming Ultra-low Interfacial Tension of Polymeric Surfactants Based on Carboxy Methyl Cellulose
    CAO Ya, LI Hui-Lin
    2001, 22(2):  312-316. 
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    The interfacial activity of polymeric surfactants based on carboxy methyl cellulose with Daqing crude oil was studied by dynamic laser scattering, environmental scanning electron microscope, spinning drop interfacial tensiometer and surface tensiometer. The results show that polymeric surfactants based on CMChave same excellent surface(interfacial) activity as low molecular weight surfactants. The surface tension of 0.5% copolymer aqueous solution is 28—35 mN/m, the interfacial tension(IFT) with Daqing crude oil is 10-1—10 mN/m. And IFTdecreases sharply after alkali is added into polymeric surfactant solutions. At the appropriate conditions, IFTof some systems reach 10-3 mN/m. The studies on equal-alkane model show, the standpoints that the action of alkali and acid components in crude oil leads to the lowest IFTare not perfect yet. The analyses by ESEMand dynamic laser scattering indicate that the micelles of polymeric surfactants disaggregate by adding alkali into solution, which leads to decrease size of micelles. And the number of mono-molecules also goes up. These changes contribute polymeric surfactants to move to and arrange in the interface of oil/water, which is the main reason of the decreasing of IFTto the lowest value.
    Preparation and Characterization of Cell Compatible Polyurethane
    GUAN Jian-Jun, GAO Chang-You, SHEN Jia-Cong
    2001, 22(2):  317-320. 
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    Cell compatible polyurethane(PU) was obtained by surface photo-grafting of 2-hydroxyethyl acrylate(HEA) onto PUmembrane surface. Hydroperoxide groups were introduced onto PUmembrane surface by photo-oxidization, then the oxidized membrane, immersed previously in monomer solution, was irradiated under UVlight. The grafted copolymers were characterized by ATR-FTIRspectra, element spectroscopy for chemical analysis(ESCA) and static water contact angle. The results showed that grafting was confined within the surface layer. Cell compatible study revealed that the attachment and growth of human umbilical vein endothelial(HUVE) cells were improved after HEAgrafting. Cells grew faster on the surface with higher oxygen content.
    Studies on the Gradient Phase Morphology of Polymer Blends Caused by Temperature Gardient
    YU Wei, ZHOU Chi-Xing
    2001, 22(2):  321-324. 
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    The gradient phase morphology of polymer blends caused by temperature gradient during quiescent annealing process was studied. The influence of volume fraction of dispersed phase and interfacial tension on the gradient phase morphology was discussed. The coarsening behavior of dispersed phase under temperature gradient was computed by the touch-coalescence mechanism. The results show that the degree of gradient phase morphology increases with interfacial tension and volume fraction of dispersed phase.
    Synthesis and Characterization of Terpolymer of Methyl Methacrylate, Styrene and Dibutyltin Maleate
    YAN Zhi-Sen, QIAN Qing-Rong, CHEN Qing-Hua, ZHANG Wen-Gong
    2001, 22(2):  325-328. 
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    Benzoic peroxide(BPO) was used as an initiator in bulk terpolymerization of dibutyltin maleate(DBTM), methyl methacrylate(MMA) and styrene(St). The conditions of copolymerization were discussed. The copolymer was characterized by GPC, IR, 1H NMRand TGanalysis; and the results showed the occurrence of copolymerization. The number-average molecular weight of terpolymer was above 104. The dynamic thermorheological test showed that, the thermal stability of copolymer was superior to that of DBTM. It may be used as polyfunctional PVCstabilizer.
    Self-assembly of Photo-responsive Azo Polyelectrolytes
    TUO Xin-Lin, CHEN Zheng, WU Li-Feng, WANG Xiao-Gong, LIU De-Shan
    2001, 22(2):  329-333. 
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    Three azo polyelectrolytes were successfully fabricated into self-assembled multilayers through a layer-by-layer dipping technique. The surface morphology and its variation with the bilayer growth were investigated with atomic force microscopy(AFM). Thecis-trans isomerization of the self-assembled thin films was studied with UV-Vis spectroscopy and compared with the spin-coated films. PEAPE/PDACand PPAPE/PDACmultilayers show significant photochromic effect upon UVlight irradiation. In dark condition, the rates ofcis-to-trans isomerization depend on the chromophore structure. For polyelectrolytes containing the same chromophores, the azo dyes in self-assembled multilayer recover much faster fromcis totrans isomer than those in spin-coated films.
    Studies on the Structure and Properties of Thermotropic Liquid Crystalline Poly(aryl ether ketone)s
    ZHANG Shan-Ju, FU Lu-Xiang, YANG De-Cai, SUN Hui, WANG Gui-Bin, WU Zhong-Wen
    2001, 22(2):  334-337. 
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    Series of thermotropic liquid crystalline poly(aryl ether ketone)s were synthesized by mucleophilic substitution reactions of 4,4'-biphenol and substituted hydroquinone with different difluoromonomers. The relationship between structure and properties of the novel copolymers was investigated. For the copolymers with liquid crystalline properties, their melting transition temperatures show no great change with increase the content of the crystal-disrupting unit. The reason is that the crystal phase is directly transformed from the ordered liquid crystal phase. Side-groups have important effect on mesophase stability. The temperature range of mesophase stability for the chloro-polymers is smaller than those of other series of copolymers(p-phenyl,t-butyl, methoxy, 3-trifluoromethylbenzene). This behavior indicates that the effect of geometric repulsive factor on the thermodynamic stability of the mesophase is much larger than that of the polarizability attractive factor. Different ordered liquid crystal phases are observed in the polymers with different molecular weights. At low molecular weight, highly ordered smectic liquid crystal phases form. With increasing the molecular weight, the ordered degree of the liquid crystals decreases, and only the nematic liquid crystal phase is observed in the polymer with higher molecular weight.
    Structural Characteristics, Syntheses and Applications of Hyperbranched Polymers
    WEI Huan-Yu, SHI Wen-Fang
    2001, 22(2):  338-344. 
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    Hyperbranched polymers have received more and more research interest from polymer scientists because of the unique strutural characteristics, synthetic methods as well as application fileds. The present paper reviews the most recent advances in hyperbranched polymer, with emphasis being laid on the above-mentioned three related aspects in an attempt to make this field to be further understood, and to accelerate it to develop more quickly. Fifty references were cited in this work.
    Graduation Initiating Radical Polymerization(Ⅰ)── Synthesis of Hyper-high Molecular Weight Polymers by Free Radical Sources
    YANG Wang-Tai, LIU Tao, YIN Mei-Zhen
    2001, 22(2):  345-347. 
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    There are presently two ways to realize “controlled/living radical polymerization”: one is by a reversible termination or reversible chain transfer to make active polymer chains continuously propagate; the other is by a physical method to suppress chain termination and to prolong radical lifetime. Here we report a new method called Graduation Initiating Radical Polymerization System for realizing “controlled/living radical polymerization”. Its principle and experimental setup are as follows: firstly, initiatable groups(i.e. peroxide groups) were introduced onto the polymer substrates like LDPEfilm by photo-oxidation reaction; secondly, the films carried peroxide groups were put and fixed to the bottom of polymerization bottle containing monomer and solvent. Afterwards, they were made to produce radicals(by heating or reductive agent), and finally the system polymerization was initiated. Once these radicals are produced on the surface of these films, they will undergo three different processes: terminating by combination, diffusing to monomer solution and taking in monomers(polymerizing). The reactive diffusion makes this system produce “two graduation”: one is the graduation of radical concentration(i.e. the farther away from the surface of the film, the lower radical concentration); the other is the length-graduation of living chains,i.e. the farther away from the surface of the film the longer the propagating chains. By this way, we could obtain a polymerization field where the radical concentration is very low and there are no primary free radicals approximately, which are benefit to realize “controlled/living radical polymerization”. This communication reports the first experimental results based on the above idea: with benzophenone(BP) as photo-catalyst and peroxide groups introduced on the LDPEsurface in a concentration 10-8 mol/cm2; by these peroxided films as the sources of free radicals, polyacrylamide and polyacrylic acid were obtained with molecular weights more than 20 millions.
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