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Table of Content

    24 June 1997, Volume 18 Issue 6
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    Articles
    Synthesis and Luminescence of a Series Terbium Ternary Complexes with 1-Phenyl-3-methyl-4-acyl-5-pyrazolones
    LI Qin, ZHOU De-Jian, HUANG Chun-Hui, YAO Guang-Qing, S. Umetani, M. Matsui
    1997, 18(6):  829-833. 
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    Aseries of terbium ternary complexes with 4-acyl substituted pyrazolones:Tb(L)3. 2H2Oand Tb(L)3. Dipy, where L=1-phenyl-3-methyl-4-acetyl-5-pyrazolone (PMAP ), 1-phenyl-3-methyl-4-propionyl-5-(PMPP), 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone (PMIBP), 1-phenyl-3-methyl-4-pivaloyl-5-p (PMPVP) and 1-phenyl-3-methyl-4-benzoyl-5-py (PMBP ), Dipy=2, 2'-dipyridyl, were synthe-sized and identified by elementary analysis. The complexes were characterized by FT-IR,UV-Vis spectra and TG-DTAanalysis. The luminescences from both the solid state and so-lution were studied and their fluorescence lifetime was determined by using the frequency-do-main method. The results show that both fluorescence intensities and lifetime of these com-plexes strongly depend on the structure of the substituted 4-acyl groups. The fluorescence intensities of the alkyl acyl substituted pyrazolone terbium complexes are three orders magni-tude stronger than that of Tb (PMBP)3 2H2O, and the introduction of the neutral ligand (Dipy) can enhance the fluorescence intensities of the complexes
    A Study of Intramolecular Electron Transfer Process of Porphyrin-anthraquinone under Photoinduction(Ⅰ)──Fluorescence Method
    WANG Xing-Qiao, WANG Cong-Xiao, WANG Qing-Min, YU Lian-Xiang, CAO Xi-Zhang, MIN Chun-Zong, WANG Li-Ping
    1997, 18(6):  834-839. 
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    In this paper, the fluorescence spectra of porphyrinanthraquinone, porphyrin-an-thraquinone Zn(Ⅱ), and parent porphyrin were studied by means of fluorescence. The ener-gy of singlet excited state(Es), fluorescence quantum yield and quench percentage were esti-mated. It is demonstrated by the data of fluorescence quench that the intramolecular electron transfer, which leads to the formation of intramolecular electric charge separating-state, oc-curred under excitation of light indeed. In the meantime, the effects of axial coordination and solvent on fluorescence property of PAQcompounds were studied.
    1H NMR Study of Interaction of cis-[Pt (NH3)2 (4-methylpyridine) Cl]NO3 with S-methylglutathione
    CHEN Bao-Wei, StellaS. G. E. VanBoom, JanReedljk
    1997, 18(6):  840-845. 
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    The interaction of antitumor activity complex, cis-[Pt (NH3)2, (4-methylpyridine )Cl]No3 with S-methylglutathione (GS-Me) was determined using the method of proton NMR. The proton resonances of Pt complex and GS-Me were used as an indication of whether the reaction was completed or not. The results indicate that a Pt- to GS-Me ratio of 1:1 is required to bind all available GS-Me- The complex of Pt with GS-Me were titrated over pHrange 1-12. The pHdependence of chemical shifts of g1, g3, g4 and g5 is depicted.It is concluded that GS-Me bind to Pt via Satom and no amino and carboxyl groups coordi-nate to Pt. The reaction mechanism was discussed and the time course of reaction was recorded. The reaction of Pt with GS-Me suggests a process in two steps: the first step in-volves the formation of Pt-GS-Me adduct via Satom, then ammonia coordinated trans to Swill be lbaialized due to the high trans effect of S. The rate constant of reaction between Pt complex and GS-Me was determined by proton NMR, k=0.017 L. mol-1. s-1 (pH3.1)and 0.013 L. mol-1. s-1(pH 7.2).
    Studies on the Conductivity and Magnetic Properties of Substituted Heteropoly Tungstogallates
    WANG Li, LIU Zong-Rui, ZHOU Yun-Shan, WANG En-Bo
    1997, 18(6):  846-850. 
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    Five substituted tungstogallate complexes were synthesized and characterized by IR, UV, ICP, TG-DTA, 183WNMR, EPR, XPS. The determination of conductivity ex-hibits that the complexes are an excellent high-proton conductor. In which, d value of GaW9Co3 is above 10-3 S. cm-1 at room temperature and 10-2 S. cm-1 at 343 K.
    Studies on the Structure of Metal Serum Albumin(Ⅷ)──A Fluorescence EXAFS Study of the Zinc Ion Centers of Zn(Ⅱ)-HSA and Zn(Ⅱ)-BSA Complexes
    Zhou Yong-Qia, ZHANG Xi-Quan, HE Jin-Tian, LIANG Xian-Zhen, OU YANG Di, HU Tian-Dou, XIE Ya-Ning
    1997, 18(6):  851-853. 
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    It has been proved that in the Zn(Ⅱ)-HSAand Zn(Ⅱ)-BSAcomplexes, the in-ternuclear distance between Zn(Ⅱ) and its nearest binding atoms is 0.201 nm and 0.203 nm, the coordinate number is about four, the coordinate atoms are probably nitrogen atoms, and the possibility of sulfur of cysteine binding to Zn(Ⅱ) is basically excluded. The results are consequently discussed.
    Nonlinear PLS Improved by Numeric Genetic Algorithm for QSAR Modelling
    HE Mei, LI Tong-Hua, CONG Pei-Sheng
    1997, 18(6):  854-859. 
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    Amethod-numeric genetic algorithm (NGA) combined with nonlinear PLS (NPLS) is proposed in this paper. NPLSis improved and the obvious prediction model can be obtained. This algorithm can deal with all kinds of nonlinear function relations. Exponen-tial, logarithmic, reciprocal and sigmoid functional formula are obtained. It is especially suitable to deal with the complicated nonlinear problem-complex structure and property relations. In this paper it is applied to solve the fungicidal activity of aseries of O-ethyl-N-isopropyl phosphoro(thioureido)thioates. It is compared with stepwise regression and PLS.The results of the correlation coefficient (R) and the standard residual (Sy
    The Recognition of UV Spectra by Using Wavelet Neural Network
    LIU Wei, XIONG Jian-Hui, WANG Hong, WANG Yong-Ming, PAN Zhong-Xiao, ZHANG Mao-Sen
    1997, 18(6):  860-863. 
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    The wavelet neural network employed in signal recognltion is presented and ap-plied to recognltion of the UVspectra of tyrosine, 3, 4-dihydroxyphenylalanine and tryto-phane. In the network, Morlet mother wavelet and line search conjugate gradient optimiza-tion method are used- The convergence speed is fast and the error of learning sets drops to 0.000073 only through 8 iterations. The error of testing patterns is 0.000064- The recogni-tion results(shown in Table 1)show that the sets of spectra can be well recognized by using the wavelet neural network.
    The Electrochemical Polymerization of Methylene Violet and Electrocatalytic Reduction of Nitrite
    WANG Yun, ZHOU Dong-Mei, CHEN Gang, CHEN Hong-Yuan
    1997, 18(6):  864-868. 
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    Astable poly (methylene violet) chemically modified electrode was prepared on the spectrum-pure graphite electrode by using cyclic voltammetry. The monomer of methy-lene violet could be polymerized on the electrode surface. The effects of various experimental conditions were discussed as for the polymerization process and the electrochemical behaviour of film was investigated in detail. The results exhibited that this film could be used for the electrocatalytic reduction of nitrite. Meanwhile, this electrode also showed a good linear cur-rent response for the NO2- in the range from 1.0×10-5 to 3.0×10-3 mol/L.
    Determination of Solubilities of Iodine and Sulfur in Supercritical CO2 Using Chromatographic Retention Method
    FANG Rui-Bin, ZHANG Shi-Hong, ZHANG Wei-Hao
    1997, 18(6):  869-872. 
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    Solubilities of iodine and monoclinic sulfur in supercritical CO2 with different pres-sures and temperatures were determined using chromatographic retention method- Solubility curves of iodine within 11-35 MPa pressure range at temperatures 313. 2, 318. 2, 323. 2,328.2 Kand monoclinic sulfur within 8.5-35 MPa pressure range at 308. 2, 318. 2, 328. 2 K, were described. Some of the results were compared with the date obtained from the methods of SFEspectrometric/gravimetric.
    Analysis of Peptides and Amino Acids by Pre-column Derivatization High Performance Liquid Chromatography with Fluorescence Detection
    LIU Xun, XU Guo-Liang, ZHANG Hua-Shan, CHENG Jie-Ke
    1997, 18(6):  873-876. 
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    Anew activated ester fluorescence derivatization reagent, N-hydroxysucci-nimidyl-3-indolylacetate(SIIA) is used for analysis of small peptides and their hydrolysates by HPLCand fluorescence detection. In a one-step procedure, SIIAreacts with peptides and amino acids to form stable derivatives. Studies on derivatization conditions demonstrate ex-cellent derivative properties of the reagent. Maximal yields are observed with a molar reagent excess of approximately twenty five or greater and heated at 60℃ for 10 min in pH 8.0 buffer. SIIAderivatives of glutathionide, diglycine, glutamic acid, cystine and glycine are separated on C18, reverse-column with the mobile phase of CH3OH/H2O (20/80, V/V)containing 10mmol/LpH 3.6 citric acid-Na2HPO4 buffer. They are detected at λcx/λcm＝278 nm/355 nm with the detection limits ranged from 0. 2 pmol to 2. 5 pmol.
    Simultaneous Determination of Vitamin B2 and B6 Using Three-dimensional Fluorescence Spectrometry by Detecting Total Fluorescence Intensity
    YAN Yuan, XU Jin-Gou, LIN Jiang, CHEN Guo-Zhen
    1997, 18(6):  877-879. 
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    In this paper, a novel fluorescence method for the determination of vitamin B2 and vitamin B6 has been established using three-dimensional fluorescence spectrometry by detect-ing the total fluorescence intensity. The sensitivity of the method, the ratio of signal to blank noise, is nearly 130 and 310 times better than that of the conventional peak intensity method for the determination of vitamin B2 and vitamin B6, respectively. This method has been successfully used to determine vitamin B2 and vitamin B6 simultaneously.
    Code for Chemical Environment and Computation of Molecular Similarity
    YANG Jia-An, XU Lu
    1997, 18(6):  880-882. 
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    Anew code for chemical environment and an empirical mathematical pattern Sam on computation of molecular similarity were suggested. Seven molecules which referred to as the probe compounds and the nearest neighbors of each probe structure were determined by the methods of Sam and Tanimoto. The results show an intuitive notion of chemical similari-ty.
    Synthesis of Salicylaldehyde-5-bromo-salicylo and Its Fluorescence Reaction with Scandium
    TANG Bo, ZHANG Sheng-Yi, JIANG Chong-Qiu, ZHANG Xiao-Gang, LI Yan
    1997, 18(6):  883-885. 
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    Anew fluorescent reagent, salicylaldehyde-5-bromo-salicyloyhydrazone (SABSH ), was synthesized and its ionization constants were established spectropho-tometrically. The fluorescent reaction of this reagent with scandium was studied in detail.Based on this chelation reaction, a spectrofluorimetric method was developed for the determi-nation of scandium in a water-ethanol(1:1, V/V) medium at pH 4.8. Under these condi-tions, the Sc-SABSHcomplex has excitation and emission maxima at 392 and 466 nm, re-spectively. The linear range of the method is from 0.0 to 1.0μg/10 mL, the relative stan-dard deviation of the method is 0.95% and the detection limit is o. 15 ng/mLof scandium when a standard additions method is used in the assay. The molar ratlo of scandium to reagent is 1: 1. Interferences of forty other ions were studied. The method has been suc-cessfully applied to the determination of trace scandium in geologic samples-
    Application of Artificial Neural Networks for Hydrocarbon Gas Mixture Analysis
    LIN Yong-Jing, ZHU Er-Yi, LI Quan-Long, YANG Peng-Yuan
    1997, 18(6):  886-888. 
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    An array composed of sixtorganiceen metal oxide semiconductor gas sensors was constructed to analyze gas mixtures quantitatively. The responses of the sensor array to ethane, propane and propylene were treated by three-layer artificial neural networks (ANN)with the method of error back-propagation and partial least-squares (PLS)- The pattern recognition results indicated that the concentration predicted with ANNis better than that with PLS. The average prediction errors for ethane, propane and propylene were 5. 11%, 8.28%, 2. 64%, respectively, in the ANNprediction.
    Synthesis and Antifungal Activity of N-Substituted-α-oxocyclododecylsulphonamides
    WANG Xiao-Ping, WANG Dao-Quan
    1997, 18(6):  889-893. 
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    Aseries of N-substituted-a-oxocyclododecylsulphonamides (Ⅲ) have been synthe-sized by amination of a-oxocyclododecylsulphonic acid chloride, obtained from the readily available cyclododecanone via a-oxocyclododecylsulphonic acid. Their structures were con-firmed by IR, MS, 1H NMRand elementary analysis. The bioassay for antifungal activitywas carried out and all the title compounds were found to be active against Gibberella zeae.The compounds showing the highest activity are those substituted by a chlorophenyl group on the nitrogen atom (Ⅲ 8, Ⅲ 7). Their structure-activity relationship was discussed by means of conformational analysis.
    A New Method for the Synthesis of 2-Aryl-3-alkyl-7-nitro-1, 4-benzoxathiin-4, 4-dioxides
    CAO Song, FAN Ai-Long, HUANG Zi-Ming, ZHANG Zheng
    1997, 18(6):  894-897. 
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    Eleven new title compounds were synthesized for the first time by treatment of α-(2-chloro-4-nitrophenylsulfonyl) acetophenones with several alkylating reagents in K2CO3-TEBA-DMFsystem via alkylation cyclization reaction. The influences of catalysts and sol-vents on the yield were studied. The possible mechanism of the reaction was suggested. The reaction may provide a new and convenient method for the synthesis of 1,4-benzoxathiin-4,4-dioxide derivatives.
    Synthesis and Crystal Structure of (R)-Thiazolidine-2-thione-4-carb Acid
    LI Ye-Zhi, GUO Chun-Xiao, HU Xue-Shan, HUANG Hua-Min
    1997, 18(6):  898-901. 
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    The title compound with [α]D20-87. 5°and yield 66% was prepared by the reaction of L-cysteine hydrochloride monohydrate and carbondisulfide in the presence of sodium hy-droxide and cupric sulfate hydrate. The crystal structure was determined by X-ray diffraction method. The crystal is orthorhombic system, space group Pz1z1z1, a=0.5029(2) nm, b=0. 7749(5) nm, c=1. 6300(5) nm, V=0. 6350(5) nm3, z=4. The electronic structure of the title compound was studied by molecular orbital PM3 method- The nature of the near frontier orbital and distribution of the calculated net charges and bond orders were obtained.The active site was described.
    Synthesis and Structure of 1-(m-Methoxyphenyl)-2-(dimethylaminomethyl) cyclohexanol
    QIAO Ben-Zhi, JIN Chun, SUN Wen-Yang
    1997, 18(6):  902-905. 
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    The reaction of 2-(dimethylaminomethyl) cyclohexanone with m-anisyl magne-sium bromlde yielded the title compound as a mixture of Z- and E-isomers, which were sepa-rated into their pure component by fractional crystallization. Their configurations were de-termined by 13CNMRspectra. The stereochemistry of the reaction was discussed.
    Influence of Magnetic Field on the Biocatalytic Properties of Ironporphyrin
    GUO Can-Cheng, HAO Xu-Dong, ZHANG Xiao-Bing, LIANG Ben-Xi, CHEN Xin-Bin
    1997, 18(6):  906-907. 
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    Monometalloporphyrin and p-oxo-bismetalloporphyrin compounds of metal iron,manganese and cobalt were synthesized, and used as the model compounds of cytochrome P-450 monooxygenase in catalytic oxidation of cyclohexane with iodosobenzene. The influence of the addition of magnetic field on the catalytic properties of these metalloporphyrins was in-spected. The studies reveal that the influence of the addition of magnetic field on the catalyt-ic behavior of other metalloporphyrins does not go beyond 37% except monoironporphyrin.But the addition of magnetic field makes the reaction yield of cyclohexane oxidation catalyzed by monoironporphyrin be increased to 53%, and makes the rate of reaction be twice as much. This fact means that the catalytic processes of cytochrome P-450 monooxygenase in human bodies may be bound up with earth magnetic field closely. This discovery has singular meaning to unlock the mystery of biosphere consisting of human and earth.
    Synthesis of Amphiphilic Metalloporphyrin Derivatives
    LIANG Qu, LIU Yun-Qi, CHEN Fu-Shen, LUO Jing-Liang, ZHU Dao-Ben
    1997, 18(6):  908-910. 
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    Metalloporphyrins posses gas-carrying property. In order to fabricate high sensi-tive gas sensor, chemical modification of porphyrin molecules by substituting both of long-chain hydrophorbic alkyloxyphenyl groups and hydrophilic hydroxyl group at their meso-po-sition could be made to meet the requirement for Langmuir-Blodgett film technique on the molecular structure. In this paper, a series of metalloporphyrin derivatives was designed and synthesized.
    Convenient Synthesis of (S)-α, α'-Diphenyl-2-pyrrolidinemethanol
    YANG Xiao-Wu, NI Jing-Man, WANG Rui, PAN Xin-Fu
    1997, 18(6):  911-913. 
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    Aconvenient synthesis of optically active α, α -diphenyl-2-pyrrolidinemethanol (1)starting from L-proline, based on different N-protections, was described. Different N-pro-tections had no effect on the optical purity of compound 1, but gave different chemical yields. The yield was the lowest when PhCH2, was employed for N-protection. An investiga-tion on the effect of N-protection on the chemical yield and the optical purity of compound 1led to a convenient preparation of the new chiral oxazolidinone 3. The structure of 3 was identified with 1H NMR, 13CNMR, MSand IR.
    Stereoselective Synthesis of (±)-Litsenolide C2
    LI Yan, CHEN Zu-Xing, HUANG Jing-Mei, HUANG Jin-Xia, XU Zhang-Huang
    1997, 18(6):  914-916. 
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    The lithihum (a-carbalkoxyvinyl) (2-thienyl) mixed higher order cyanocuprate, de-rived from ethyl propargylic ester with (n-C13H27) (2-thienyl)CuCNLi2, reacted with cis-1-bromo-l-propylene under Pd (PPh3)4 catalysis to give a diene ester ethyl 1- (Z-propylidene)-1-E-hexadecenate. Then the target product (±)-litsenolide C2 was stereoselectively synthe-sized by employing cis-dihydroxylation of the diene ester using a NMO-OsO4 system as the oxidant and stereospecific lactonation by acidic catalyst. The ratio of Eto Zcarbon-carbon double bond is >98: 2, and the ratio of trans- and cis-disubstituted lactones is >95: 5.
    A Convenient Synthesis of 4-O-Ethylepipicropodophyllin
    QIN Bing-Chang, CHEN Ning, YANG Min, WU An-Xin, PAN Xin-Fu
    1997, 18(6):  917-919. 
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    This paper reports the improved synthesis of 4-O-ethylepipicropodophyllin 5 in two steps starting from Podophyllotoxin 1. The method is more efficient and convenient than the synthetic route from references.
    Purification of Recombinant Human Interferon-γ by High-Performance Hydrophobic Interaction Chromatography and Size Exclusion Chromatography
    GUO Li-An, LIU Shu-Lin, ZHU Bao-Quan
    1997, 18(6):  920-922. 
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    Adownstream purification procedure for recombinant human interferon-γ(rhIFN-γ) expressed in E. coli was described. An essentially two-step chromatographic purification procedure, i. e., size exclusion chromatography(SEC) and high-performance hydrophobic in-teraction chromatography (HPHIC), was used for purification of homogeneity of rhIFN-γ from the inclusion body. The specific activity of purified rhIFN-Ywas 1.0×108 IU/mg pro-tein. The product of purification rhIFN-γ was analyzed by an analytical high-per formance SECand a significant sigle symmetrical peak had been found. The purity of purified rhIFN-Ywas greater than 95% from analysis, determination by analytical HPSECand SDS-PAGEwith Coomssie Blue. The molecular weight was ca. 15000. It was shown that this procedure was an effective method for purifying rhIFN-γ.
    Study on Ytterbium Chalcogenides by Means of Density Functional Theory
    DAI Da-Di, LI Le-Min
    1997, 18(6):  923-927. 
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    The ytterbium chalcogenides have been studied by means of the density functional theory(DFT). The validity of the present approximate DFTformulas and the influence of relativistic effects for the lanthanide compounds have been examined by comparing the calcu-lated results with the experiments. The results show that the bond length of YbOobtained from DFTcalculations differs from the experimental value by about 0.002 nm- However,the bond energies are overestimated by DFT, even though both the gradient corrections and relativistic effects are taken into account. Introducing the exchange gradient coorrections on the basis of LDAcan reduce the calculated bond energies. Among the examined formulas for the exchange gradient correction, the formula PW86x produces a little lower energies and gives better results. The correlation correction increases the calculated bond energies. The relativistic effects make the bond lengths shorter by 0.004-0.006 nm, and make the bond energies lower by about 0. 5 eV. Analysis of the obtained results shows that the σ- and π-bonds are formed through the interaction between the 5d orbitals of Yb and the nPorbitals of the ligands. The populations in the 5d orbitals of Yb decrease through YbOto YbTe, fol-lowing the trend of the decrement of the bond energies. The relativistic effects destabilize the bonds, which may be due to the fact that the 6s electrons of Yb transfer to 5d orbitals in bond formation while the relativistic effects raise the energy of this process. The obtained dipole moments and charge distribution show that the bonds in ytterbium chalcogenides bear large covalence components which are increased by the relativistic effects.
    The Relation of Electronic Configuration of Transition Metal Complex Oxides to the Surface Photovoltaic Response(Ⅰ)──The Studies of M(Ⅱ)Fe2O4(M=Cu, Co, Ni)
    LI Kui-Ying, WANG De-Jun, YU Jian-Feng, WU Tong-Hao, SUN Jia-Zhong, LI Tie-Jin
    1997, 18(6):  928-931. 
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    The relations between the photovoltaic response of transition metal complex ox-ides and their electronic configuration were studied by the surface photovoltage spectroscopy (SPS) and field induced surface photovoltage spectroscopy(FISPS) techniques. The results showed that the complex oxide with open-shell Cu(Ⅱ) has more intense low-energy CTtran-sition; Cu(Ⅱ) complex oxide and low-spin d7 Co(Ⅱ) complex oxide has composition of dou-blet exited states; Whereas CTtransition of closed-she1l d8 Ni (Ⅱ) needs larger energy-These conclusions were confirmed by the test of the reaction catalytical activity-
    Electrooxidation of Propanol on Highly Preferred Orientation(220) Nickel Electrode in Alkaline Media
    HUANG Ling, XU Shu-Kai, ZHOU Shao-Min
    1997, 18(6):  932-937. 
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    Ni electrode with (220) highly preferred orientation was obtained with potentio-static electrodeposition in the solution containing1.0mol/L NiSO4 and 0. 5 mol/L H3BO3.The Ni electrode deposited at - 1.25 Vfor 60 min was examined with X-ray diffaction. It was shown that the Ni electrode has a highly preferred orientation with texture degree of 92%. The mechanism and catalytic activities of propanol oxidation on the highly preferred orientation (220) Ni electrode were studied with cyclic voltammetry. It was shown that the electrocatalytic activity of the Ni electrode for propanol oxidation is higher than that for iso-propanol. The kinetic equation of propanol electrooxidation was derived. The kinetic param-eters were measured with polarization curves- The rate constant [K1, (E)] for the oxidation of Ni(Ⅱ) to Ni(Ⅲ) is 5. 25×10-13exp(0. 488FE/RT), The rate constant [k-1(E)j]for the re-duction of Ni(Ⅲ) to Ni(Ⅲ) is 2. 46×10-4exp(-0.512FE/RT) and the rate constant (k2)for the oxidation of propanol by Ni(Ⅲ) is 5. 64×10-6 L. mol-1s-1.
    Photoelectrochemical Studies on the Nano-Porous TiO2/Polypyrrole Film Electrode
    LIU Min-Sheng, YANG Mai-Zhi, HAO Yan-Zhong, YU Chen, CAI Sheng-Min, LI Yong-Fang
    1997, 18(6):  938-942. 
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    The photocurrent conversion processes of nanoporous TiO2/poly pyrrole (PPy)film electrode were studied in the electrolytes with or without redox couple by using the pho-tocurrent action spectra, the potential dependence of photocurrent and UV-Vis absorption spectra. lt is concluded that nanoporous, TiO2/PPy film electrode has a duplex n-type semi-conductor layer structure. The bandgap of nanoporous film is 3. 26 eV, and the bandgap of PPy film is 2. 2 eV. There fore, the semiconductor electrode modified by PPy can enlarge the visible optical absorption region and increases obviously the photocurrent in vislble region. The photocurrent threshold shifts to>600nm and this effect can improve the photon-elec-tron conversion efficiency of the semiconductor electrodes of large bandgap.
    The Generation Mechanism of Gaseous [(SiO2)nX]- Clusters
    XU Can, ZHANG Rong-Jun, ZHU Lei, ZHAO Li, QIAN Shi-Xiong, LI Yu-Fen, LONG Ying-Cai
    1997, 18(6):  943-946. 
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    Many sequences of [(SiO2)nX]-clusters are found under XeCl excimer laser abla-tion of several condensed state SiO2-based materials in the negative channel of the time-of-flight mass spectrometry. The unique roles of the network structure and surface-active groups in laser energy absorptance, transfer and the cluster formation mechanism also have been discussed.
    Structures and Electronic Spectra of C70R2(R=OH, CH3)
    TENG Qi-Wen, WU Shi, HAO Ce, ZHAo Xue-Zhuang, TANG Au-Chin, FENG Ji-Kang
    1997, 18(6):  947-950. 
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    The structures and stabilities of the four isomers of C70R2(R=OH, CH3) were in-vestigated by using INDOmethods. It was indicated that the most stable isomers for C70(OH)2 are 1, 9- and 7, 8-isomers, of which the decrease of energy is 38.5 kJ/mol, and 7, 8-isomer of C70(CH,)2 is more stable than1, 9-isomer by 23. 0 kJ/mol. The theoretical pre-diction for the electronic spectra of C70R2(R=OH, CH3) was performed based on the opti-mised geometries, and the electronic transition was assigned as well as the red-shift of the absorptions was rationalized.
    Synergic Effect of Multimetallic Catalysts in the Cyclotrimerization of Butadiene
    SUN Qi, LIAO Shi-Jian, XU Yun, YU Dao-Rong, CHEN Shou-Shan
    1997, 18(6):  951-954. 
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    The synergic effect of multimeta1lic catalysts by the addition of the second transi-tion metal compound to the TiCl4/AlEt1.46Cl1.54 system has been investigated in the cy-clotrimerization of butadiene. The experimental results indicate that with the addition of a very small amount of the second metal compound, Cr(acac)3, Mn(acac)3, NiCl2, ZrCl4 etc.to the Ti-Al system, the selectivity of cyclotrimerization of butadiene was improved(except Ni (OAc)2), the maximum turnover frequency (TOFmax.) and turnover (TO ) were changed.The second metal compound should be added to Ti-Al system before Ti active species formed, otherwise no synergic effect will be observed- The second metal compound/AlEt1.46Cl1.54 systems alone can catalyze the dimerization(Cr, Mn, Fe, Zr sa1ts) or polymerization (Ni, Co salts) of butadiene.
    The New Experimental Evidence for Protonational Site of Heteropoly Blue──Investigation by in-situ FTIR Spectroelectrockemical Method
    ZHANG Shu-Yan, SUN Hao-Ran, XING Yong-Heng, YANG Guo-Yu, XU Ji-Qing
    1997, 18(6):  955-957. 
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    The electrochemical reduction processes of heteropolyanion PMo12O403- in protonic media were investigated by in-situ FTIRspectroelectrochemical method' Experimental re-sults indicated that the protonational site of electroreduction product HnPMoMo12O403-(n= 2, 4,6, 8) was on bridge oxygen atom- The infrared characteristic absorption peaks of Mo = 0double bound shift to higher frequence after electroreduction of heteropo1yanion PMo12O403-.This result can be interpreted from the viewpoint of induction effect of proton.
    Studies of TPR in situ 57Fe MBS on the Reduction Behavior of the γ-Al2O3 Supported Iron and Platinum-iron Catalysts
    JIA Ji-Fei, SHEN Jian-Yi, XU Zhu-Sheng, GE Xin, ZHANG Tao, LIN Li-Wu
    1997, 18(6):  958-960. 
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    The reduction behavior of Y-Al2O3 supported iron and platinum-iron catalysts was studied by TPRcombined in situ 57Fe MBS. The results indicated that Fe3+ is highly dis-persed on the Y-Al2O3 surface for all the samples containing iron before the reduction. No Fe0 was found in the reduction process. The Fe3+ was reduced to Fe2+ in tetrahedral vacancy first in Pt-Fe/Y-Al2O3 sample in TPRprocess. The TPRprocesses of all supported iron samples are very different from those of α-Fe2O3/sub>.
    Electrochemical Preparation for Bioactive Ceramics Coating on Ti-6Al-4V Substrate
    ZHANG Jian-Min, LIN Chang-Jian, FENG Zu-De, TIAN Zhao-Wu
    1997, 18(6):  961-962. 
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    An electrodeposition technique was developed for fabricating bioactive hydroxyap-atite(HA) coating on Ti-6Al-4Valloy at relative low temperature. XRD, SEMand ICP/AESwere used to characterize the structure, morphology and chemical composition of the coatings. The galvanostatic electrodeposted HAcoating is of 1.62 Ca/Pmolar ratio and has a uniform and porous structure, which is similar with the structure and composition of hu-man bone. The reaction mechanism and influence of experimental conditions on HAcoatings are also discussed.
    Synthesis of Liquid Crystalline Aromatic Amide Compounds
    ZHANG Dong, ZHOU Qi-Feng, MA Yu-Guo, WAN Xin-Hua, FENG Xin-De
    1997, 18(6):  963-967. 
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    The synthesis and characterization of a new series of aromatic amide compounds that have only amide linkage between the phenyl rings are reported. Some of them are found to be thermotropic liquid crystals. Aromatic amide compounds are considered undesirable for forming thermotropic liquid crystal because the extensive hydrogen bonding among the molecules would result in too high the melting point- In this study, we found that the aro-matic amide compounds with proper lateral substitution on center phenylene and proper ter-minal groups at the two ends of the rod-like molecules were able to form thermotropic liquid crystalline phases.
    Gel Point and Mechanism of Gel Formation in Copolymers from Free-Radical Crosslinking Polymerization of Vinyl/Divinyl Monomers
    LUO Ying-Wu, WENG Zhi-Xue, HUANG Zhi-Ming, PAN Zu-Ren
    1997, 18(6):  968-972. 
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    After discussing the results from the computer simulations of gel point in the vinyl/divinyl monomer free-radical crosslinking polymerization by several typical models, the authors proposed that gel point be distinguished from mechanism of gel formation. The crite-ria of gel point is the appearing of the macromolecule whose average crosslinking density is equal to 1/DPpwHowever, the gel formation can have two processes of nucleation and growth, where the condition of nucleation is that the average crosslinking density in one macromolecule of a sol becomes1/DPpw
    A Study of Photoconductive Polyimides (Ⅰ)──Synthesis, Characterization and the Photoconductivity Study of Polymers Containing Carbazole and Phthalocyanine Groups
    CHEN Yuan-Sheng, XU Zhi-Kang, ZHU Bao-Ku, XU You-Yi
    1997, 18(6):  973-977. 
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    Polyamic acid with carbazole and copper-phthalocyanine was synthesized by con-densation polymerization. Heat resistant polyimide was obtained by thermal treatment of the polyamic acid. It was found that the initial degradation temperature of the polylmide was more than530℃ and it was confirmed by IRanalysis that the polyamic acid was completely converted to polyimide after the heat treatment process. The photoconductivity of the P/Rsystem has been improved by the incorporation of phthalocyanine group into the polyimide main chain.
    Synthesis and Properties of Porous Starch Graft Copolymers Beads
    GE Yu-Bin, WU Yong-Ge, SUN Wen-Tian, ZHOU Hui, Ll Wei, SHEN Jia-Cong
    1997, 18(6):  978-980. 
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    Porous starch graft copolymers(PSGC) beads were synthesized and their proper-ties were studied. The PSGCbeads prepared have good mechanical properties and high porosity(about 30%-40%), the pore size is about 19. 5 nm. The PSGCbeads are stable in the range of pH3.13 as well as in boiling water. They contain large amount of active groups making them suitable for use as support material for immobilized enzymes.
    Rheological Properties and In-situ Reinforcement of Liquid Crystalline Copolyesteramide/Poly(ethylene terephthalate) Blends
    XIE Xiao-Lin, WU Da-Cheng
    1997, 18(6):  981-984. 
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    The binary blends of liquid crystalline copolyesteramide(PEA) and poly(ethyleneterephthalate, PET) were studied by Instron3211 type capillary rheometer, The spinnability of the blend melts was inverstigated based on their rheological properties- The relationship between the mechanical properties and structure was discussed. The results show that the viscosity of blends is lower than that of PETand there is a minimum of viscosity at 10%PEAcontent. When the content of PEAis less than 10%, the blends are well-spinnable,and the composite fibers have a well-developed highly oriented fibrillar structure along the fiber axis. As the PEAis 5%, good in-situ reinforcement can be obtained.
    A Study of Ultrasonic Copolymerization of Polymer Surfactants Based on Carboxy Methyl Cellulose
    CAO Ya, LI Hui-Lin, XU Xi
    1997, 18(6):  985-989. 
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    The copolymerization by ultrasonic irradiation of carboxy methyl cellulose(CMC)with macromonomer (alkyl poly (etheroxy) acrylate) and comono-mer(styrene) was studied.The purified products were characterized by IR, 13C NMRand UVspectra, the results show that the copolymer prepared is mainly a block one. Ultrasonic irradiation time and monomer weight fraction in the feed have great influence on structure and properties of copolymers.Copolymers prepared by ultrasonic irradiation have a high viscosity and a good surface activi-ty.
    Isolation and Structural Analysis of Polysaccharides from the Sclerotium of Poria Cocos Wolf
    ZHANG Li-Na, DING Qiong, ZHANG Ping-Yi, FENG Han-Qiao
    1997, 18(6):  990-993. 
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    Five polysaccharides (PC1, PC2, PC2-A, PC3 and PC4) were isolated from a fresh sclerotium of Poria cocos by using 0.9% NaCl aqueous solution, hot water, 0. 5 mol/L NaOHaqueous solution and 88% formic acid, respectively. The components and structures of the polysaccharides were analyzed by IR, GC, HPLC, 13CNMRand 1H NMR. The polysaccharides of PC1, PC2 and PC2-Aconsist of D-glucose, D-xylose, D-mannose and D-galactose, and the D-glucose content increases with the progress of isolation process. The PC1 and PC2-Acontain glucuronic acid. The polysaccharide PC3 contains mainly linearβ-(1-3)-D-glucan, and is the major fraction of Poria cocos polysaccharides. The PC4 is com-posed of β-(1-3)-D-glucan with a few of braching and glucuronic acid.
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