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    24 September 2000, Volume 21 Issue 9
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    Articles
    Synthesis and Property of SrFeCo0.5O 3.25+δ Ultrafine Powders and Oxygen Permeation Membranes
    LIU Wei, CHENG Kai, ZHANG Guo-Guang, CHEN Chu-Sheng, LIU Xing-Qin, PENG Ding-Kun
    2000, 21(9):  1335-1338. 
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    SrFeCo0.5O 3.25+δ (SFC) ultrafine powders with appropriate dispersibility and sintering properties were synthesized by glycine-nitrate-process (GNP) method and used for the preparation of oxygen permeation membrane. Compared with those of SFCmembranes synthesized by conventional solid-state reaction method, the phase structure, microstructure, conductivity and oxygen permeation properties of the SrFeCo0.5O 3.25+δ ceramic membrane material were studied. The results revealed that the SrFeCo0.5O 3.25+δ system mainly consisted of perovskite and layered phases. Its oxygen permeation flux is about 1.2×10-8mol·cm-2 ·s-1 in air/helium gradient at 950 ℃, which is higher than that of sample prepared by solid state reaction method.
    The Crystal Structure and VUV Luminescent Property of the Rare Earth Borates
    YANG Zhi, REN Min, LIN Jian-Hua, SU Mian-Zeng, TAO Ye, WANG Wei
    2000, 21(9):  1339-1343. 
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    The VUVabsorption of rare earth borates depends strongly on the structure of the borate ions. It is proposed from the simple extended Hückel calculation that the excitation transition in the VUVrange is mainly from the B—O bonding orbital(HOMO) to the antibonding orbital(LUMO). The energy difference between the HOMOand LUMOdecreases in the sequence of BO45->B2O54->BO33->B3O99-, which accords with the VUVexperimental results.
    Template Effect of Tartrate Ion on the Morphology of Antimony Trioxide
    LI Qi-Hou, XIAO Song-Wen, LIU Zhi-Hong, GUO Xue-Yi, ZHANG Duo-Mo
    2000, 21(9):  1344-1347. 
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    This paper describes the influence of tartrate ions on the crystal growth and morphology of antimony white(Sb2O3), which was characterized by XRD, IRand SEM. The relationship between the orientation of tartrate ions and the morphology of Sb2O3 was studied from the standpoint of crystal chemistry, and the formation mechanism of Sb2O3 with different morphologies was analyzed according to the theoretical model of the growth units with coordinative polyhedron structure of anion. It revealed that the products transformed from the orthombic Sb2O3 to the cubic Sb2O3 due to the molecular recognition of tartrate anion with a strong coordination ability, which changed the original growth unit of SbO3Ecoordinative tetrahedron into the growth unit of SbO 3+3Estellar quadrangle.
    Circular Dichroism Study on Ternary Copper(Ê) Complexes with Diiodotyrosinates and Related Amino Acids An Approach to Structural Role of Iodine for Thyroid Hormone Activation
    ZHANG Feng, SONG Xi-Ming, LIU Qi-Tao
    2000, 21(9):  1348-1352. 
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    Circular dichroism (CD) spectra of the ternary copper(Ê) complexes with 3,5-diiodo-L-tyrosine (L-I2tyr), L-tyrosine (L-Tyr), or L-homoserine (L-Hser) and amino acids L-/DL-AA, where AArepresents arginine (Arg), lysine (Lys), asparagine (Asn), glutamine (Gln), or alanine (Ala), have been determined in the d-d region in various ionic strength (I=1.0 or 0.1 mol/L KNO3) and solvents(H2O, 50%(U)ethanol-H2O, or 50%(U)dioxane-H2O). The spectra exhibit a maximum at 599~623 nm for all the ternary complexes, and the $E for Cu(L-I2tyr)(L/DL-Arg) and Cu(L-I2tyr)(L/DL-Lys) are abnormally negative (-0.493~-1.072); the $E for Cu(L-I2tyr)(L/DL-AA) are obviously more negative than that for Cu(L-Tyr)(L/DL-AA). The possible ligand-ligand interactions in these ternary complexes were discussed, and the structural effects of the iodo groups on the interaction were emphasized.
    Synthesis of Ultrafine Zeolite NaY(Ⅰ) Effect of Light Rare Earth Ions Additive
    CHAO Zi-Sheng, LIN Hai-Qiang, CHEN Guo-Zhou, WU Ting-Hua, WAN Hui-Lin, MIN En-Ze
    2000, 21(9):  1353-1358. 
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    Ultrafine zeolite NaYwas hydrothermally crystallized with silica sol and Al2(SO4)2 as source materials via optimizing synthesis conditions and adding light rare earth ions(Ln 3+) to the synthesis batch. The crystallization performance of NaYcould be affected by the aging time of nucleation Si-Al gel and the crystallization temperature of reaction Si-Al gel. With increasing the aging time(2—7 d) of nucleation gel, the crystallization rate of zeolite NaYincreased whereas the average crystal size of zeolite NaYdecreased. When elevating the crystallization temperature(363—383 K) of reaction gel, both the crystallization rate and the average crystal size of zeolite NaYincreased. Nevertheless, the crystallization performance of zeolite NaYwas more remarkably affected by the addition of Ln3+ ions in the synthesis batch. The crystallization rate and the n(SiO2)/n(Al2O3) ratio obviously increased while the average crystal size greatly reduced when zeolite NaYwas crystallized in the presence of Ln3+ ions, comparing with that in the absence of Ln3+ ions. It was found that, with the amount of the added Ln 3+ ions increasing, the average crystal size of zeolite NaYdecreased followed by increasing, while the crystallization rate and the SiO2/Al2O3 ratio in framework changed in the opposite direction. The optimal amount of Ln 3+ additive appears to be in the range of n(Ln3+)∶n(Al 3+)=0.05∶1—0.1∶1 in mole. In the case, the as-synthesized NaYzeolites had the smallest average crystal sizes(<100 nm), the highest n(SiO2)/n(Al2O3) ratio(>5.7) and the shortest crystallization time(<36 h). The role of the added Ln3+ ions was proposed to be that there formed the micro-crystalline Ln(OH)3 under the synthesis conditions, which may present additional area to initiate the nucleation of zeolite NaY.
    Synthesis and Characteristics of New High Temperature Stationary Phase [60] Fullerene Polysiloxane for Capillary Gas Chromatography
    FAN Jian-Hong, ZENG Zhao-Rui, FANG Peng-Fei, CHEN Yuan-Yin, CHENG Jie-Ke
    2000, 21(9):  1359-1363. 
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    Two new fullerene-containing polysiloxanes were synthesized by reacting [60] fullerene with azidepropyl polysiloxane directly and used as the stationary phases for capillary gas chromatography. It demonstrated a high column efficiency, wide operational temperature and outstanding thermostability. It can be used at 360 ℃ with a baseline drift of 3×10-144×10-14 nm. The stationary phases were especially suitable for separation of high boiling compounds like monosaccharides, polycyclic aromatic hydrocarbons and phthalic diesters, etc. It was also found that some alcohols or aromatic positional isomers can be well separated on the column.
    Determination of Rutin and L-Ascorbic Acid in Pharmaceutical Preparations and Fruit Juices by Capillary Zone Electrophoresis with Electrochemical Detection
    CHEN Gang, DING Xiang-Huan, YE Jian-Nong
    2000, 21(9):  1364-1368. 
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    A simultaneous detemination of rutin(RT) and L-ascorbic acid(Vc) in pharmaceutical preparations and fruit juices by capillary zone electrophoresis with electrochemical detection(CE-ED) was reported. The effects of potential of working electrode, concentration and pHof the running buffer, separation voltage and injection time on the CE-EDdetermination were investigated and discussed. RTand Vc could be well separated in a 25 mmol/Lborax-50 mmol/L NaH2PO4 buffer(pH8.0) with in 12 min. A 300 μm diameter carbon disc electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at potential of 1.0 V(vs. SCE). There are excellent linearity between peak current and concentration of analytes in the concentration range of 1.0×10-6—2.5×10-4 mol/L for RT and 5.0×10-6—2.5×10-3 mol/Lfor Vc with the detection limits(S/N=3) of 8.0×10-7 and 3.3×10-6 mol/Lfor RTand Vc, respectively. Relative standard deviations(RSD) of the peak currents of RTand Vc were 2.85%(RT) and 1.65%(Vc) based on 9 determinations of the same sample containing 5.0×10-5 mol/L RTand 2.5×10-4 mol/L Vc. Recoveries of 97.94% for RT and 99.68% for Vc were obtained based on 5 determinations.
    Application of A New Stationary Phase Bonded with Macrocyclic Dioxopolyamine in Open-Tubular Capillary Electrochromatography
    ZENG Zhao-Rui, GUAN Na, WANG Yuan-Chao, FU En-Qin, CHENG Jie-Ke
    2000, 21(9):  1369-1371. 
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    The macrocyclic dioxopolyamine compounds, 1,4,7,10-tetraazacyclotridecane-11,13-diones were used as stationary phases with the aid of 3-(2-cyclooxypropoxyl)propyl-trimethoxy silane as a bridge in open-tubular capillary electrochromatography(OTCEC). The capillaries were etched by aqueous sodium before being coated. These modified capillaries had shown improved separations of neurotransmitters, isomeric dihydrobenzenes, isomeric nitrophenols and isomeric aminophenols in comparison with untreated capillaries.
    Investigation on the Electrochemical and Electrocatalytic Behavior of Chemically Modified Electrode of Single Wall Carbon Nanotube Functionalized with Carboxylic Acid Group
    LUO Hong-Xia, SHI Zu-Jin, LI Nan-Qiang, GU Zhen-Nan, ZHUANG Qian-Kun
    2000, 21(9):  1372-1374. 
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    The electrochemical behavior of the film of single wall carbon nanotube(SWNT) functionalized with carboxylic acid group was studied extensively at the glassy carbon(GC) electrode. One stable couple of waves corresponding to the redox of the carboxylic acid group, which was supported by the IRexperiments, was observed. The electrode process involved four electrons, while the rate determining step was a one-electron reduction. The SWNTfilm modified electrode showed nice electrocatalytic behaviors toward the oxidations of some biomolecules such as dopamine, epinephrine and ascorbic acid.
    Studies on a Novel Sulfur Dioxide Gas Electrochemical Sensor
    XIAN Yue-Zhong, XUE Jian, ZHANG Wen, JIN Li-Tong, JIANG Xue-Guo, YAN Shuang-Long
    2000, 21(9):  1375-1376. 
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    The development of a novel electrochemical sensor for the detection of concentration of atmospheric sulfur dioxide in the low-mg/m 3 range is described. The gas sensor is based on a platinum microelectrode and a porous polymer film, which is directly connected with the gas-containing atmosphere. The gas sensor is very sensitive, selective, and reproducible for detection of SO2. The linear range over 0.10 mg/m3 to 150 mg/m3 and the detection limits is 005 mg/m3.
    Intramolecular Charge Transfer and Electron Transfer in N-(1-Naphthyl)aminoacetic Acid in Aqueous Solution
    MA Li-Hua, WEN Zhen-Chang, SUN Xiang-Ying, JIANG Yun-Bao
    2000, 21(9):  1377-1379. 
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    pH titration of the fluorescence of N-(1-naphthyl)aminoacetic acid(NAA) was performed in aqueous solution over pHrange of 1.5—12.5. Despite no shift in the fluorescence maximum wavelength, the titration curve showed an Ω-shaped profile with increasing pH with two inflection points at pH 4.1 and pH 11.5, respectively. These values correspond to the excited-state pKa*'s of carboxylic group and ammonium cation, respectively, which are both higher than those of the corresponding ground-state pKa's of 264 and 1183, of which the former changes more. The substantial weakening of the proton dissociation of carboxylic group in the excited state should be indicative of the decrease in the inductive+I-effect of the ammonium cation at the β-position due to the excited-state intramolecular charge transfer from naphthalene moiety to ammonium. The latter was also confirmed by the slight increase in the exited-state pKa2*. The fact that the increase in pKa1* is larger than that in pKa2* suggests that the effect of the intramolecular charge transfer on the involved moiety be weaker than that on a remote moiety in the same species. This could be taken into consideration for designing means of tuning the structures and properties of peptide and protein via photo-excitation. It was identified that the NAAzwitterion(Ⅱ) was the emissive species. The fluorescence quenching at high pH was assumed to be due to the photo-induced intramolecular electron transfer between carboxylate anion and the excited naphthalene moiety. The present case represents an example in which both intramolecular charge transfer and electron transfer occur to shape the pHtitration profile.
    Fabrication of Metal Oxide-based Solid pH Electrode
    LI Qing-Wen, LUO Guo-An, SHU You-Qin, CHE Hong-Li
    2000, 21(9):  1380-1382. 
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    Nanosized metal oxides were recommended as pH-sensitive materials to fabricate solid pHsensors with screen printable technique. The metal oxide electrodes studied in this paper showed a better selectivity to hydrogen ions with the presence of alkali ions. Particularly, the outstanding advantage of these electrodes was that these electrodes were available to measure the pHof the highly corrosive system containing HF.
    Studies on Electrocatalytic Oxidation of AA at β-Cyclodextrin-ferrocene Inclusion Complex Modified Carbon Paste Electrode
    WANG Xiao-Lei, ZHANG Guo-Rong, SHI Xing-Wang, SUN Tian-Lin
    2000, 21(9):  1383-1385. 
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    Inclusion complex of ferrocene(Fc) with β-cyclodextrin(β-CD) has been synthesized in ethylene glycol. It was unsolvable in water and had been successfully used in the preparation of β-CD-Fc inclusion complex modified carbon paste electrode (CFCPE). Using the inclusion complex as the electroactive substance greatly increased the stability and reproducibility of CFCPEthan using Fc.
    Synthesis of 6-Nitrobenzimidazole Derivatives
    LIU Su-Yan, HUI Xin-Ping, XU Peng-Fei, ZHANG Zi-Yi 
    2000, 21(9):  1386-1390. 
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    Aseries of new s-triazolo[3,4-b]-1,3,4-thiadiazole, 1,2,4-triazole and 1,3,4-oxadiazole derivatives were synthesized from 6-nitrobenzimidazol 1-acetic acid hydrazide and 4-amino-5-mercapto-3-(6-nitrobenzimidazol 1-methylene)-1,2,4-triazole, respectively. The structures of the compounds synthesized were confirmed by elemental analyses, 1H NMR, IRand MS. Their spectral properties were also discussed.
    Studies on the Stereoselectivity of Pinacol Coupling Reaction Mediated by TiCl4-Mg
    LI Ting-You, WANG Li-Ping, ZHANG Tao, LI Yao-Xian, WANG Zong-Mu
    2000, 21(9):  1391-1394. 
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    TiCl4-Mg and TiCl4-Mg-TMEDAsystems are used as reagents of pinacol coupling reaction, thus reductive coupling of aromatic aldehydes with a high stereoselectivity. The observed stereochemistry of the reaction is briefly discussed in term of Ti-bridging controlled models. Three kinds of chiral auxiliary 1,4-diamines, 1,4-diphosphines and 1,4-diethers, are used in the pinacol formation reaction of benzaldehyde mediated by TiCl4-Mg, and hydrobenzoin was obtained with ee 50% of (R,R)-isomer. when N,N,N',N'-tetramethyl-2,3-O-isopropylidene-2,3-dihydroxy, 1,4-butanediamine was used as chiral modifier.
    The First Total Synthesis of (±)-Sinaiticin
    SHE Xue-Gong, GU Wen-Xin, JING Xiao-Bi, PAN Xin-Fu 
    2000, 21(9):  1395-1398. 
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    (±)-Sinaiticin was first synthesized by nine steps in 13.4% overall yield. In this approach the conversion of cis-6 to trans-7 by epimerization and the oxidative cyclization reaction are the key steps.
    Synthesis of Some Polyhydroxysterols and Investigation of Relationship Between Their Structure and Cytotoxicity
    CUI Jian-Guo, ZENG Long-Mei, SU Jing-Yu, PENG Wen-Lie, XU An-Long
    2000, 21(9):  1399-1404. 
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    In this paper, we have prepared six analogues of 24-methylenecholest-4-en-3β,6β-diol(1) and investigated the relationships between the biological activity and their structures. The results showed that the double bond in the molecule played an impor tant role to the cytotoxicity of these polyhydroxysterols. Their cytotoxicity reduced obviously while the double bond in steroidal nucleus or side-chain was saturated. Compounds 5 and 8 showed a moderate cytotoxic activity against human gastric carcinoma cells(MGC) and cervical carcinoma cells(HELA).
    Studies on the Syntheses and Properties of o-Methoxycarbonylbenzyl Substituted Calix[4]arenes
    XING Yan-Jun, ZHOU Zhi-Xian, DU Chen-Xia, WU Yang-Jie
    2000, 21(9):  1405-1407. 
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    Two new substituted calix[4]arene derivatives 2 and 3 were synthesized by the reaction of calix[4]arene with methyl o-bromomethyl-benzoate in the presence of potassium carbonate under nitrogen. Their compositions and structures were confirmed by elemental analysis, IR, 1H NMRand 13C NMR. Both the compounds are in the cone conformation. The percent extraction of the tetrasubstituted calix[4]arene derivative 2 for Li+, Na+, K+ and Cs+ are 6.8, 19.4, 69.8 and 7.1, respectively, indicating that derivative 2 extracts K+ better than Li+, Na+ and Cs+. The higher selective complexation of compound 2 with K+ elucidated that the radius of potassium cation may be matched with the inclusion cavity formed by the carbonyl and phenoxy groups. There is only a little extractivity of disubstituted calix[4]arene derivative 3 for alkali metal ions.
    Asymmetric Synthesis of Optically Active1,1'-Bi-2-naphthol
    SU Wu, WANG Heng-Shan, DA Chao-Shan, WANG Rui 
    2000, 21(9):  1408-1409. 
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    Experimental results are reported for the CuCl2-mediated asymmetric oxidative coupling of 2-naphthols in the presence of [-]α-methylbenzylamine to optically active (S)-(-)-1,1'-bi-2-naphthol. Under anhydrous conditions and with a 3∶1 molarity ratio of α-methylbenzylamine to 2-naphthol, a fair enantioselection has been observed(up to 80.6% ee).
    Improvement Preparation Method of N3-(Hydroxyalkyl) Tagefur and Synthesis and Activity of Its Cyclic Glycerophospholipid Conjugate
    XU Xin-Hua, CHEN Huan-Ming, CHEN Ru-Yu
    2000, 21(9):  1410-1412. 
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    N1-(2-Fursnidyl)-5-fluorouracil reacted with multimethylenes chlorohydrin in the presence of NaHCO3 in acetonitrile at 80 ℃ to give N1-(2-furanidyl)-N3-(hydroxyalkyl)-5-fulorouracils in a high yield (≥93%). Their cyclic glycerophospholipid conjugates were synthesized and had a good activity against the man urinary bladder cancer cell in vitro.
    Synthesis and Characterization of p-Dodecaoxydithiobenzoic Acid-Nickel(Ⅱ) Complex as Stationary Phase of Liquid Crystal Type
    XIONG Yu-Tang, HU Yong-Gang, XIA Chi-Zhong
    2000, 21(9):  1413-1415. 
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    p-Dodecaoxydithiobenzoic acid-nickel(Ⅱ) complex with a liquid crystal nature(DDBN) was synthesized and characterized by using the differential scanning calorimetry(DSC) and GC. DSCmeasurements showed that DDBNexhibited a mesomorphic behavior and that the phase transition occurred at 95 ℃ and 125 ℃. The dependence of lg k'vs. reciprocal temperature for cycloparaffins indicated also the same temperature of phase transition. In this paper, DDBNwas used first as the stationary phase to the separation of positional isomers. The results indicated that DDBNwas stable at temperature ranging from 80 ℃ to 240 ℃ and adequate for the separation of isomer of polycyclic aromatic hydrocarbon. 1-Methylnaphthalene and 2-methyl-naphthalene were separated at the baseline using3 m×3 mm column of DDBN. Phenanthrene and anthracene were separated also easy using the same column. The infinite-dilution partial molar enthalpy and entropy of four analytes in this system were obtained by means of plotting. Thermodynamic properties and the mechanism for retention were also discussed.
    Ab initio and DFT Study on Electronic Structures and Photoelectric Properties of Tris-8-hydroxyquinoline Aluminum
    SU Zhong-Min, CHENG Hong, GAO Hong-Ze, SUN Shi-Ling, CHU Bei, WANG Rong-Shun, WANG Yue
    2000, 21(9):  1416-1421. 
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    By means of ab initio HFand DFT B3LYPmethods, the structure of tris-8-hydroxyquinoline aluminum(AlQ3) was optimized. The electronic transition mechanism in AlQ3 has been analyzed. The results suggest that the electronic π-π* transitions in AlQ3 are localized on the quinolate ligands; the transition from a phenoxide donor to a pyridyl acceptor includes C→Cand O→Ntransferences. There hardly is any relation to the metal aluminum. Considering the importance of ligand 8-hydoxyquinoline in AlQ3, we designed three derivatives of AlQ3 and discussed their possibilities as luminescent materials. The derivatives of AlQ3 maybe possess a high luminescence efficiency.
    Electrochemical Determination of the Energy Level of Organic/Polymeric Materials
    SONG Wen-Bo, CHEN Xu, WU Fang, TIAN Wen-Jing, MA Yu-Guang, XU Hong-Ding
    2000, 21(9):  1422-1426. 
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    We focus on the study of energy level structure of organic systems(taking AlQ3 for example) using two newly developed electrochemical methods(derivative voltammetry and coulomb-potential spectroscopy), and devote our attention to comparing the accuracy of these new methods with conventional methods. The experimental values of the HOMOand the LUMOpositions of AlQ3 and PVKare in good agreement with the results determined by the photoemission analysis. The experimental band gap values for AlQ3 and PVKobtained via two new methods are also in excellent agreement with the band gap values deduced by the optical absorption spectroscopy. The resulting organic/polymeric electroluminescent devices based on matching energy level of organic/polymeric system exhibit a high luminescent efficiency.
    Theoretical Studies on the C—H Bond Insertion Reaction of Carbenes with Ethers (Ⅱ) Insertion Reactions of CX2(X=F, Cl) with Dimethylether
    LIN Qi-Jun, FENG Da-Cheng, MA Wan-Yong
    2000, 21(9):  1427-1431. 
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    The insertion reactions between singlet CX2(X=Cl, F) and C—Hbonds of dimethyl ether have been calculated at the MP2/6-31G(d) level by using ab initio molecular orbital theory. Both the two insertion reactions are spontaneous and the course of the insertion is electophilic-neucleophilic one for CX2. The potential barriers are 125.9 kJ/mol(133.2 kJ/mol after zero-point energy correction, X=Cl) and 255.3 kJ/mol(257.6 kJ/mol after zero-point energy correction, X=F), respectively. In fact, it is very difficult for CF2 to undergo insertion reaction at room temperature.
    State-transition in the Chemical Birhymicity of CuSO4-H2O2-KSCN-NaOH Reaction System by Modulating Flowrate
    WEI Qing-Li, CHEN Lan, WU Qi-Lin, CAI Zun-Sheng, ZHAO Xue-Zhuang 
    2000, 21(9):  1432-1436. 
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    Two types of birhymicity(Ⅰ, Ⅱ) of CuSO4-H2O2-KSCN-NaOHreaction system are found to be in continuous flow stirred tank reactor(CSTR). The transitions between two oscillatory states in the birhymicity Ⅱ region of the present chemical reaction have been induced by the application of a sinusoidal flowrate signal. One-way transition, i.e., from one oscillation to another oscillation(OSS1→OSS2 or OSS2→OSS1), only occurs in the two critical regions of birhymicity Ⅱ. The switching between OSS1 and OSS2 can be observed at kf0=4.0 mL/min in OSS1 and kf0=3.0 mL/min in OSS2 by certain periodical modulation.
    Hydrophilicity and Photocatalytic Activity of Self-cleaning Porous TiO2 Thin Films on Glass
    YU Jia-Guo, ZHAO Xiu-Jian
    2000, 21(9):  1437-1440. 
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    The porous TiO2 thin films deposited on glass surface were prepared from alkoxide solutions containing polyethylene glycol(PEG) by a dip-coating technique. The effects of PEGaddition to the precursor solution on the photocatalytic activity and hydrophilicity of the resultant thin films were studied. The larger the amount of PEG, the larger the adsorbed hydroxyl content in the as-prepared porous thin films, the better the hydrophilicity. The contact angle between water and the porous TiO2 thin films declines to zero. The glass with porous TiO2 thin films possesses self-cleaning function and is easily washed. However, the transmittance of the glass with porous TiO2 thin films decreases due to the enhancement of light scattering of the larger pores(400 nm). The photocatalytic degradation experiments show that methyl orange aqueous solution was efficiently decolorized in the presence of the porous TiO2 thin films by illumination with a 125 Whigh pressure mercury lamp. The photocatalytic activity of the TiO2 thin films is obviously enhanced by the PEGaddition to the precursor solutions. On the other hand, when the amount of PEGreaches 2.0 g, the photocatalytic activity will drop.
    4-Nitrophenyl Acetate Hydrolysis Catalyzed by Cu(Ê) and Zn(Ê) Complexes of Linear Oxa-Aza Polydentate Amino Alcoholic Phenol Ligands
    XIE Yong-Shu, YU Jun, LIN Rui-Sen, LIU Qing-Liang
    2000, 21(9):  1441-1444. 
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    The kinetics of p-nitrophenyl acetate(NA) hydrolysis catalyzed by Cu(Ê) complexes of ligands N,NØ-bis-(2-hydroxyethyl)-ethylenediamine(L1) and N-(2-hydroxybenzyl)-3-amino-propan-1-ol(HL2) and Zn(Ê) complexes of ligands N-(2-hydroxyethyl)-NØ-(2-hydroxybenzyl)-ethylenediamine(HL3) and 3,6,9-triaza-1-nonanol(L4) was determined spectrophotometrically at (25±0.1) ℃ and I=0.10 mol/L KNO3 in U(CH3CN)=10% at pH 6.5—9.0(50 mmol/Lbuffers), and the second-rate constants kC for the catalysis of NAester hydrolysis were obtained. The experimental results indicate that coordinated alkoxides Cu(Ê)… -ORand Zn(Ê)… -ORyielded at neutral pHare strong nucleophiles, and the complexes have a strong ability to catalyze the hydrolysis of NAester following the double-catalysis mechanism, with kC values of 6.72×10-2, 0.126 , 4.55×10-2 and 7.66×10-2 mol-1·L·s-1.
    Development of Higher Stable Ni/MgO Catalyst for CO2 Reforming of Methane
    LI Ji-Tao, CHEN Ming-Dan, YAN Qian-Gu, WAN Hui-Lin, TSAI K. R.
    2000, 21(9):  1445-1447. 
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    Methane reforming by carbon dioxide has been studied over Ni/MgOcatalysts prepared by two impregnation methods which were common and promoted with support salt(magnesia salt). The catalysts were characterized by TPR, TPD, TPOand TPMC(temperature programmed methane decomposition to carbon deposition) techniques. The promoted catalyst exhibited a higher ability to adsorb CO2 and lower ability of CH4 decomposition. Therefore the carbon formation was inhibited and the catalyst stability was increased more.
    Studies of Adsorbed Species of CO, H2 and CO/H2 over ZrO2
    WU Gui-Sheng, CHEN Xiao-Ping, REN Jie, SUN Yu-Han
    2000, 21(9):  1448-1450. 
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    The adsorption of CO, H2 and CO/H2 on ZrO2 was investigated by in situ FTIR. H2 species adsorbed over ZrO2 produced two bands at 3780 and 3680 cm-1, corresponding to ZrOHZr and ZrOH, respectively. COadsorbed on ZrO2 formed formate species at 200 ℃, which slowly decomposed to COwith the rise of adsorption temperature. The formate over ZrO2 could be hydrogenated into methoxide species and methane in H2. As a result, the hydrogenation of methoxide, which proceeded slowly relatively, seemed to be the rate-determining step.
    Preparation, Characterization of Cu-MCM-41 and Its Catalysis for Hydroxylation of Aromatic Compounds
    SUN Jian-Min, MENG Xiang-Ju, WANG Run-Wei, LIN Wen-Yong, LIN Kai-Feng, PANG Wen-Qin, JIANG Da-Zhen, XU Ru-Ren, XIAO Feng-Shou
    2000, 21(9):  1451-1454. 
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    Pure silica MCM-41 with surface grafted Cu2+ ions(donated as CuMCM-41) was synthesized via a novel co-assemble route; XRD, ESRand ion-exchange studies revealed that the copper was located on the surface of the pure silica MCM-41 and coordinated with bridged oxygen in the framework. In addition, we also studied its catalysis behavior for hydroxylation of phenol and naphthol with hydrogen peroxide as the oxygen donor. The experimental results show that Cu-MCM-41 possesses an excellent catalytic activity compared with other catalysts Cu-AlMCM-41 and CuO-MCM-41.
    Studies on Charge Transfer of Polyimide Rings
    BAI Xu-Duo, ZHANG Zhi-Qian, FENG Ji-Kang, XIE Gang, CHEN Jiu-Shun
    2000, 21(9):  1455-1458. 
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    Charge distributions, dipole monents and transition energies for model compounds of polyimide structure units in ground state and excited state were studied by ab initio calculation. Fluorescence spectra of polyimides were determined and differences of forming charge-transfer complex between two polyimides in excited state were explored. The results showed that large charge transfer occurred on the imide rings consisting of 1,4-diaminobenzene and 4,4′-diaminotriphenylamine in ground state but further charge transfer occurred on the imide ring consisting of 4,4′-diaminotriphenylamine in excited state .
    Morphology Observation of DNA LB Film by AFM
    CHEN Xia, JIN Jian, YANG Wen-Sheng, YANG Bai-Quan, XU Li, JIANG Lin, BAI Yu-Bai, LI Tie-Jin, CHEN Xi
    2000, 21(9):  1459-1461. 
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    DNA/octadecylamine(ODA) monolayers were transferred onto silicon substrates and the morphologies of the monolayers were investigated by Atomic Force Microscope(AFM). AFMimages show that the morphologies of DNAdissolved in pure water are very different from those of DNAdissolved in the NaCl solution. When DNAmolecules are dissovled in pure water, they will form ball-like structure in the monolayer. When the DNAmolecules are dissolved in NaCl solution, they will form bunch lines. This DNAline offers a valuable template to direct the formation of unique inorganic nanomaterials.
    A Novel Catalyst for Direct Vapor Phase Carbonylation of Ethanol
    PENG Feng, LIU Zhen-Hua
    2000, 21(9):  1462-1464. 
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    A novel Mo/Ccatalyst, which are reduced in H2 after sulfidizaing ammonium heptamolybdate with (NH4)2Saqueous solution, has a high activity and selectivity for ethanol vapor phase carbonylation to ethyl propionate without addition of any promoter in the feed. Ethanol carbonylation is carried out in a fixed bed reactor with a continuous flow system at atmospheric pressure. This catalyst has a higher initial activity and selectivity; the catalytic activity reaches steady state after carbonylation reaction for 30 min. Higher temperatures led to a sharp decrease of the carbonylation activity and to an increase of the selectivities of ethene and ether. The optimal reaction conditions are as follows: reaction temperature is 553 K; n(C2H5OH)/n(CO)=4/1; GHSV=4.0 L/(g cat·h). Under these conditions, the conversion of ethanol is 80%, the selectivity of ethyl propionate is 80.6% and the space-time yield is 1.157×10-2 mol/(g cat·h). This result is surprisingly better than that of ethanol vapor phase carbonylation over Ni-Zn/Ccatalyst with addition of ethyl iodide promoter to the feed [n(C2H5OH)/n(C2H5I)=10/1], especially, this novel Mo/Ccatalyst has a significantly higher selectivity. No carbonylation product is found over Ni base catalyst without addition of the promoter. This research demonstrates that novel Mo/Ccatalyst may be promising for ethyl propionate production from the carbonylation of ethanol at atmospheric pressure, without requiring ethyl iodide as promoter. This novel catalyst is found to be a non-crystalline by X-ray diffraction. The Mo content in the catalyst is 10%.
    Enthalpic Interaction Parameters of Glucose with Some Heterocyclic Compounds in Formamide
    TANG Qing-Hu, LU Yan, BAI Tong-Chun, ZHAO Pei-Zhen, LU Jin-Suo
    2000, 21(9):  1465-1467. 
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    The molar enthalpies of glucose solution, in the mixtures of some heterocyclic compounds and formamide, have been determined at 298.15 Kby a C-80 colarimeter. Depending on the McMillan-Mayer theory, the values of pair and triplet interaction parameters hxy, hxyy and hxxy between solutes have been fitted by using a least square method. The information about the solute-solute interaction and the effect of solvent on the interaction were discussed.
    A Nonorthogonal Tight-binding Study of Silicon-Germanium Mixed Clusters GemSin(m+n≤10)
    LI Si-Dian, JIN Zhi-Hao
    2000, 21(9):  1468-1469. 
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    The geometrical structures and binding energies of GemSin mixed clusters(s=m+n≤10) have been optimized based upon the nonorthogonal tight-binding scheme. GemSin mixed clusters are found similar in structures with Sin and Gen(but with lower symmetries) and the binding energies of the mixed clusters are between the corresponding values of the Sin and Gen.
    Effects of Rare Earth on Methanol Fuel Exhaust Deep Oxidation over Ag Catalyst
    WANG Xing-Yi, WAN Ying, LU Guan-Zhong
    2000, 21(9):  1470-1472. 
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    The performance of deep oxidation of methanol on supported Ag catalysts was examined by a chromatograph-micro-reactor. The research results showed that La and/or Ce added into γ-alumina support affected greatly the activity and selectivity of methanol oxidation on Ag catalyst. La could lower light-off temperature of methanol oxidation and decreased the content of intermediate containing oxygen, but at low temperature HCOOCH3 formed. Ce had an unfavorable role. The addition of La and Ce into catalyst could cause the effects of these elements to offset. By XPStechnique, it was showed that La and Ce could change the chemical valence of Ag inversely, which corresponded to the modifications of catalytic performance.
    Measurement and Model of Molecular Weight for Styrene/N-Phenylmaleimide Copolymer
    SHAN Guo-Rong, WENG Zhi-Xue, HUANG Zhi-Ming, PAN Zu-Ren
    2000, 21(9):  1473-1476. 
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    The molecular weight theory and calculation equation of copolymer were set up after consideration with the influence of composition and sequence distribution. The molecular weight for St/PMIcopolymer was investigated by means of GPCconnected with DRand UVdetectors. From the mechanism of St/PMIcopolymerization, a model of molecular weight for St-PMIcopolymer was proposed to predicate the effects of initiator concentration, feed fraction and conversion on the molecular weight of St-PMIcopolymer. The predicted results coincided with the experimental data.
    Studies on Microemulsion Copolymerization of N-Butyl Maleimide and Styrene
    ZHAO You-Liang, LI Hua-Ming, LIU Peng-Sheng 
    2000, 21(9):  1477-1480. 
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    The complexion properties of N-butyl maleimide(NBMI) and styrene(St) in CDCl3 were studied firstly. By using sodium dodecyl sulfate(SDS) and pentanol(PTL) as emulsifier, the oil-in-water microemulsion containing NBMIand St was prepared. The microemulsion copolymerization was carried out in ampoules with potassium persulfate(KPS) as initiator. The effects of reaction temperature, molar fraction of monomer and initiator concentration on the copolymerization kinetics were studied in detail under the condition of keeping the emulsifier concentration at 0.21 mol/L SDSand 0.28 mol/L PTL. Monomer reactivity ratios of comonomer pairs were determined by a Lewis and Mayo method. Meanwhile, the effects of monomer feed on the Tg and intrinsic viscosity of poly(NBMI-co-St)s were also investigated. The experiment results showed that the Tg of alternating poly(NBMI-co-St) was 421.6 K, and the monomer reactivity ratios of NBMI(M1) and St(M2) were 0.05(r1) and 0.08(r2), respectively. Moreover, it was found that the resulting copolymer was of alternating structure when the molar fraction of NBMI(f1) varied from 0.4 to 0.7.
    Investigation on Avrami Equation of PET and PBT in Crystallization
    BIAN Jie, YE Sheng-Rong, FENG Lin-Xian
    2000, 21(9):  1481-1484. 
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    Depolarized light intensity technique was applied to investigating the isothermal crystallizing kinetics characteristics of polyethylene terephthalate(PET), polybutylene terephthalate(PBT) and PET-PBT, PBT-PBIcopolyesters under various conditions. The results show that the crystallization rate constants and the Avrami exponents change regularly under various conditions. Avrami exponents were mostly not integer. Therefore, it is presumed that Avrami exponent indicate the number of growth points in crystal nucleus.
    Image Reversal Techniques with a Water-based Chemical Amplified Photoresist
    CHEN Ming, LI Yuan-Chang, HONG Xiao-Yin, JIAO Xiao-Ming, CHENG Ai-Ping
    2000, 21(9):  1485-1488. 
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    Awater-based chemical amplified photoresist, which is composed of Novolak resin, hexamethoxylmethyl melamine(HMMM), diphenyliodonium salt and photosensitizer was investigated. It was found that the diphenyliodonium salt can act not only as the photosensitive acid generator, but also as the dissolution inhibitor. As a photosensitive acid generator, the diphenyliodonium salt can generate acid after exposure, which catalyzes the condensation of Novolac-HMMMsystem in post-exposure bake step. Using the alkali-ethanol aqueous solution as the developer the photoresist can be of negative tone. As a dissolution inhibitor, the diphenyliodonium salt can prevent the unexposure film from being dissolved in the developer. Therefore, using the dilute alkali aqueous solution as developer this photoresist can be of positive tone. Image reversal can be achieved by selecting different developer and different photographic process. The negative tone image and the positive tone image were obtained by the optimized photolithographic parameters.
    Synthesis of C1 Bridge-containing Metallocene Catalysts and Their Catalytic Activities for Olefin Polymerization
    ZHOU Guang-Yuan, JIN Guo-Xin, HUANG Bao-Tong
    2000, 21(9):  1489-1493. 
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    The synthesis and characterization of metallocene complexes which can be used as catalysts in the presence of MAOfor olefin polymerization were discussed in the present paper. The metallocene complexes have been characterized by IR, 1H NMR, EI-MSspectra and element analyses. The catalytic features of olefin polymerization were studied under different conditions. Metallocenes in which metals is Ti had no activity for ethylene polymerization. Polymers with different features can be obtained by using different catalysts.
    Living Free Radical Ring-opening Polymerization of 5,6-Benzo-2-methylene-1,3-dioxepane
    YUAN Jin-Ying, ZOU Ying-Fang, PAN Cai-Yuan 
    2000, 21(9):  1494-1496. 
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    In order to clarify whether Atom Transfer Radical Polymerization(ATRP) method could be extended to free radical ring-opening polymerization, the polymerization of a kind of unsaturated cyclic acetal: 5,6-benzo-2-methylene-1,3-dioxepane(BMDO) in the presence of α,α'-dibromoxylene as the initiator and CuBr/2,2'-bipyridine as the catalyst and ligand at 120 ℃ was investigated. IR, 1H NMRand 13C NMRspectra of the polymer obtained showed that BMDOunderwent quantitatively ring-opening polymerization and linear polyesters were prepared. GPCcurves indicated that the polyesters had a narrower molecular weight distribution. Molecular weight of the polyesters could be controlled by polymerization time and adjusting the molar ratio of monomer/intiator consumed. The polymers with narrower polydispersities were obtained, and first-order kinetics of polymerization was observed. These facts proved that BMDOunderwent “living” free radical ring-opening polymerization. And this is the firsr report on the “living” free radical ring-opening polymerization of unsarurated cyclic acetal using atom transfer radical polymerization method. The results of ln([M]0)/[M]) against polymerization time, Mn vs. conversion, and molecular weight distribution of the polymers are indicative of the “living” polymerization process.
    A New Interpretation of Huggins Coefficient in the Viscosity Equation for Polymer Dilute Solution
    PAN Yan, CHENG Rong-Shi 
    2000, 21(9):  1497-1499. 
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    The chain length dependency of molar association constant Ka of polymer in solution was investigated theoretically. Ka is proportional to the effective hydrodynamic volume Veff of polymer chain in solution. Veff is the product of a shape factor and hydrodynamic volume. On the basis of these results, the observed enhancement of Huggins coefficient for short chain and branched polymer could be satisfactorily interpreted.
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