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Table of Content

    24 March 2000, Volume 21 Issue 3
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    Articles
    Determination of Double Decker Sandwich Structure of Praseodymium-chlorophyll a Molecule
    WEI Zheng-Gui, HONG Fa-Shui, ZHAO Gui-Wen, Tao-Ye, Hu-Tian-Dou, WANG Wei, LIU Tao, XIE Ya-Ning, WU Zhong-Hua
    2000, 21(3):  331-334. 
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    The Pr(Ⅲ) complex of Chlorophyll a was synthesized and characterized. The results of UV Vis and IRspectra indicate the coordination of Pr(Ⅲ) to the porphyrin rings. The special bands in Soret band region in MCDspectra shown a transition type of the sandwich structure porphyrin complexes. By extended Xray Absorption Fine Structure(XAFS) method, a double decker sandwich structure was well fitted, in which Pr is surrounded by eight nitrogen atoms from two porphyrin rings. Combining the MCDwith EXAFSresults, it is believed that the binding mode of Pr ion in chlorophyll a is a sandwich structure with the Pr—Nbond length of average 0.242 nm.
    Preparation of Active Carbon with High Specific Surface Area From Rice Husks
    GUO Yu-Peng, YANG Shao-Fang, ZHAO Jing-Zhe, WANG Zi-Chen, ZHAO Mu-Yu
    2000, 21(3):  335-338. 
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    The active carbon with a high specific surface area(more than 3 000 m2/g) was prepared by activating the carbonized rice husks by using potassium hydroxide as the activating agent.The effects of preparation parameters on the properties of the active carbon were studied, and its structure was characterized preliminarily.
    Microstructure and Surface Topography of Aluminum Films Deposited on Glass Microspheres in a Fluidized Bed CVD Reactor
    LIU Shu-Qin, SHI Da-Xin, CUI Yi-Hong, CAO Zhu-You
    2000, 21(3):  339-343. 
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    In this paper, we investigate the influences of deposition temperature and time on microstructure and surface topography of the aluminum films deposited on glass microspheres of higher refractive index by thermal decomposition of tri isobutyl aluminum in a fluidized bed CVDreactor at atmospheric pressure. SEMexamination of surface topography of the films shows that under the same conditions, the increase of deposition temperature causes the aluminum films to change from 3-dimensional hillock formation to non specular, rough structure with steep peeks and valleys to uniform and smooth surface; and while extending the deposition time at certain temperatures, the grains become larger and surface roughness becomes distinct. The results demonstrate that by means of thermal activation at appropriately elevated temperatures(350~390 ℃) for a certain period of time(about 30 min), it is possible to provide smooth and uniform aluminum films on the surface of glass microspheres which may approximately conform with the requirements of retro-reflective materials. Auger spectra for examining the surface chemical composition reveal that the preferred higher temperature used to obtain smooth topography does not introduce obvious contamination by carbon residues, but diffusion of Ti and Ba from substrates toward aluminum film occurs to some extent, which may be another factor to cause the activation of the substrate and to obtain smooth and uniform aluminum film on glass microspheres in this study. In order to further improve and control microstructure and surface topography of the aluminum films, it is necessary to adopt other appropriate activation process combined with thermal activation.
    An Oxide Direct Conversion Route to Nanocrystalline Mercury Chalcogenides
    DING Yi, LIU Ren-Mao, ZHANG Zu-De, QIAN Yi-Tai, LI Ya-Dong
    2000, 21(3):  344-346. 
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    An oxide direct conversion route was reported to synthesize the nanocrystalline HgE (E=S,Se,Te) in ethylenediamine at room temperature. Mercury oxide was used as mercury source and sulfur, selenium, tellerium, respectively, as chalcogenide sources. XRDpatterns show that the obtained samples are hexagonal(wurtzite structure) HgS, cubic (zinc blende structure) HgSe and HgTe. The influences of solvent and reaction temperature were investigated and it was found that the ethylenediamine plays a crucial role in the conversion process.
    Synthesis and Structure of Dinuclear Copper(Ê) Complex with Nitronyl Nitroxide Biradical [Cu(hfac)2]2PhBNOM
    ZHAO Qi-Hua, LIAO Dai-Zheng, JIANG Zong-Hui, YAN Shi-Ping, FANG Rui-Bin, ZHU Hong-Ping
    2000, 21(3):  347-349. 
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    Dinuclear copper complex with biradical, [Cu(hfac)2]2PhBNOM[PhBNOM=2,5-bimethoxyl-1,4-bis(4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide)phenyl, hfac=hexafluoroacetylacetonate], has been synthesized and characterized. It crystallized in the monoclinic system; space group C2/c with a = 1.8773(8) nm, b =1.3598(5) nm, c =2.2371(7) nm, β =97.24(3)°, Z =4, R = 0.0961 , Rw=00944 .
    Determination of Iron(Ⅱ) and Total Iron Using Flow Injection On line Preconcentration With FAAS
    XU Guang-Ming, YE Ying-Xue, YIN Xue-Feng, SHEN Hong, Akbar-Ali
    2000, 21(3):  350-353. 
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    Adirect, rapid and sensitive method for the determination of Fe(Ⅱ) and Fe(Ⅲ) in water samples by flame absorption spectrometry coupled with flow injection on line preconcentration with 1,10-phenanthroline(1,10-phen) as the complex agent was developed. Various parameters affecting the complex formation and its subsequent adsorption, such as pHof the mixture solution, 1,10 phen concentration, sample flow rate etc. were optimized. A 25×10-3 mol/L 1,10 phen in 2.0% ethanol was on line mixed with aqueous sample solution of iron in 0.1%(volume ratio) hydrochloric acid and flowed through the microcolumn for 30 s. Fe(Ⅱ) can be extracted as Fe(Ⅱ)-phen complex in the C18 microcolumn and determined within 10 s in the nebulizer of FAASafter being eluted by ethanol. Ascorbic acid(0.1 mg/mL) was used for the reduction of Fe(Ⅲ) to Fe(Ⅱ). Agood precision(RSD=1.1%, n =10), high enrichment factor(19) and sample throughput(80 h) with detection limit 3 μg/Lwere obtained. The method has been successfully applied on the water sample for Fe(Ⅱ) and Fe(Ⅲ) determination with the recovery 94%—105%.
    Theoretical Study on the Photoelectric Behavior of Mammalian Cells
    ZHANG Chun-Yang, CI Yu-Xiang
    2000, 21(3):  354-357. 
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    The effectiveness of doxorubicin, oligomycin and cholchicine on living cells was studied with the photoelectric method in this paper. The results indicated that the change of photoelectric current can reflect the effectiveness of drugs on living cells, and the inhibition effect of drugs on the photoelectric current of living cells was dependent on the drug concentration and drug-treating time. Based on these results, a model of “light-induced enzymatic-reaction acceleration” for the photoelectric behavior of mammalian cells had been proposed as well.
    A Multivariate Linear Model for Calculating Response Feature Parameters of Chemical Sensor Based on Fluorescence Quenching for Analytes
    LI Wei, CHEN Jian, XIANG Bing-Ren, AN Deng-Kui
    2000, 21(3):  358-362. 
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    Amathematical model was deduced and described for the different mechanism of fluorescence quenching to analytes based on the essential quenching models including the dynamic quenching, the resonance energy transfer and the inner filter effects involving absorption of both excited light from the light source and emitted light from membrane. The model reported here indicated that the logarithmic functions of the intensity of fluorescence modulation in virtue of multiple quenching factors conform to the rule of addition. The response feature parameters of chemical sensor based on fluorescence quenching for analyses could be calculated by combining the multivariate linear model with a tri cup method. Aconception based on regarding the chemical sensor as the second source of light was advanced to get more useful information on analytes. The pyrenebutyric acid was chosen as a fluoroprobe for constructing the chemical sensor to response a series of the therapeutic drugs. Atrain of thought for constructing the quantitative analysis model for the chemical membrane sensors based on the fluorescence quenching was afforded in the light of the experimental results.
    Studies of Selective Enrichment and Recognized Characteristics of Paracetamol Molecular Template Polymer
    GUO Hong-Sheng, HE Xi-Wen, DENG Chang-Hui, LI Yi-Jun
    2000, 21(3):  363-367. 
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    Amolecular templated synthetic polymer as the receptor highly selective for paracetamol was prepared by a molecular imprinting technique. The selective binding characteristics of the template polymer were evaluated by Scatchard analysis and Ultraviolet spectrometry. The results showed that the acrylamide as the functional monomer was more better than methacrylic acid for paracetamol selectivity, and a class of the same binding sites which could specially bind paracetamol by the interaction of hydrogen bonding were formed in the polymer and its dissociation constant was estimated to be 225×10-3 mol/L. The selective binding experiment for substrates indicated that the polymer gave a higher affinity and selectivity for paracetamol. It is possible to be a good adsorption and binding material in the selective enrichment and determination of trace paracetamol in complex biosamples.
    Studies on the Calibration of Matrix Effects and Polyatomic Ion for Rare Earth Elements in Geochemical Samples by ICP-MS
    HU Sheng-Hong, LIN Sou-Lin, LIU Yong-Sheng, GAO Shan
    2000, 21(3):  368-372. 
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    The calibration method was developed for the matrix effects and polyatomic ion of the analysis of rare earth elements in the geological samples. Matrix effects were minimized by using synthetic calibration solutions which simulated the composition of natural rocks by statistically calculating the average values of 20 geological samples and normalization. Two separate internal standards of 115In-103Rh were selected to compensate the drift of analytical signals. Polyatomic ions were calibrated by measuring the oxides (MO+) and hydroxide (MOH+) with individual La, Ce, Pr and Ba solution for the ratio of MO+/M+ and MOH+/M+ and calculating equivalently concentrations. The proposed method has been applied to the analysis of AGV-1(Andesite), BHVO2-(Basalt), GSR-3(Basalt), DNC-1(dolerite) and RGM-1(rhyolite). The relative error between this work and the recommend values are better than 10% and the relative standard deviations are better than 5%.
    Studies on Thiocyanate selective Electrodes Based on Novel Neutral Carriers
    LI Zhi-Qiang, SHEN Guo-Li, YU Ru-Qin
    2000, 21(3):  373-376. 
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    The anion response characteristics of transition metal chelates of a new Schiff base was systematically investigated in this paper. The results show that the electrode response characteristics have close relationship with the properties of the central metals, the electrodes based on the Mn(Ⅱ) chelate exhibited an excellent potentiometric response and selectivity towards thiocyanate. The linear response range of the electrode was (0.1~4.3)×10-6 mol/Lwith a slope of-58.0 mV/dec., the anti Hofmeister selectivity pattern was: SCN->I->Sal->PhCO2->ClO4->NO2->Br->Ac->NO3->Cl-. The response mechanism was investigated by A.C. impedance and the effect of charged additives on the response characteristics and selectivity of the electrodes. It can be concluded that the electrodes exhibited Nernstian response to thiocyanate via a neutral carrier-based mechanism. The novel electrodes have advantages of being fast, accurate and stable, and can be used for the determination of thiocyanate in actual samples.
    Perturbation Effect of Ultra Trace Hydrogen Peroxide on the MnSO4-KBrO3-Diacetone Oscillating Chemical Reaction
    ZHANG Ke, CAI Ru-Xiu, MA Wan-Hong, LIN Zhi-Xin, GAN Nan-Qin
    2000, 21(3):  377-379. 
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    The similarities between life processes that exhibit oscillatory behavior and chemical oscillating systems impel people to think that the biological and abiological phenomena conform to the same law. Oscillating chemical systems have been the focus of much research in the area of theoretical and experimental chemical dynamics as well as analytical sciences in recent years, but the studies on the perturbation species are kept around the concentration level of 10-7 mol/L. In our experiment, an amazed phenomenon was found. Ultra trace level (10-20 mol/L) of H2O2 can cause so magnitude influence on the macro system (MnSO4-KBrO3-diacetone oscillating chemical system) that the effect can be observed by a macroscopical method. When the concentration of H2O2 is above 10-13mol/L , the oscillation can even be stopped. Afurther study on the mechanism will doubtlessly help to understand the mystery of life, such as the sudden cardiopathy and the metabolism failure.
    Determination of Surface pKaof HS(CH2)10COOH SAMs Using an Electrochemical Titration Method
    LUO Li-Qiang, ZHAO Jian-Wei, YANG Xiu-Rong, WANG Er-Kang, DONG Shao-Jun 
    2000, 21(3):  380-382. 
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    The self assembled monolayer(SAM) of 11-mercaptoundecanoic acid [HS(CH2)10COOH] was formed on a gold electrode and the effect of the charge of end group on the electrochemical response of Fe(CN)3- 6 at the SAMmodified electrode was studied by cyclic voltammetry. At high pH, when the —COOHgroups are dissociated, the current of Fe(CN)63- is suppressed; as the solution pHis lowered, the current of Fe(CN)63- increases. The electrochemical titration curve was obtained by correlating the currents of Fe(CN)63- to the different pHvalues of electrolyte, from which the surface pKa was obtained to be 3.0±0.2. Furthermore, the reason of small pKa value was explained using SAMs of different surface coverage.
    Preparation of RP-packings with Low Adsorption by after Gellating
    YU Xin, ZHAO Rui, QIAO Xia, HE Xiu-Juan, WANG Yun-Fu, LIU Guo-Quan 
    2000, 21(3):  383-385. 
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    A C18 RPpacking with low adsorption was prepared by use of gelation reaction. Benzene, phthlene, phenanthrene, aniline and pyridine were selected as test solutes to evaluate the column with a mobile phase of 65% ACNaqueous solution. The performance and the stability were showed well after 1000 column volume of 65% ACNaqueous solution(containing 0.1% TFA) .The strong polar alkine molecular can be separated well.
    Studies on X-ray Photoelectron Spectra of Meso-ionic Compound 2-Arylamino 1,3,4-thiadiazolium-5-thiolates
    ZHANG Zi-Yi, CHU Chang-Hu, SUN Xiao-Wen, QI Shang-Kui, LI Zhi-Chun, LIAO Ren-An
    2000, 21(3):  386-390. 
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    The structures of 2-arylamino-1,3,4-thiadiazolium-5-thiolates(4) were confirmed by Xray photoelectron spectra. The meso ionic were prepared from 2-arylamino 1,3,4-thiadiazol-5-thiones by using ω-bromo-ω-(1H-1,2,4-triazol-1-yl)acetophenone(2). The results showed that the binding energies of C1s, N1s , and S2p in meso-ionic 4 are greater than those in the correspondence compounds 1, which were more obvious in N1s and S2p . For example, N1s showed three signals in mesoionic 4 and only two signals and in compounds 1 because the chemical environment of thiadiazole rings two nitrogen atoms are different in4 and same in1. Furthermore, the additive binding energy of S2p in ring is greater than the exocyclic one for the same mesoionic 4.
    Studies on the Asymmetric Synthesis of Precursor of Vitamin B12 Ring-B Imide and Succinimide Drugs
    WANG Heng-Shan, JIA Qiang, YANG Xiao-Wu, WANG Rui
    2000, 21(3):  391-394. 
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    From γ-butyrolactone 1, we synthesized (S)-2-methyl-2-nitroethenyl butyrolactone (S)-3 by the mean of direct enantioselective construction of molecule with quaternary carbon stereocenter on the bases of our previous research. (S)-3 was obtained in36% overall yield with 94% optical purity. We established a set of conversions from(±)-3 to the precursor of Vitamin B12 ring Bimide 8 under mild conditions and complete the synthesis of three derivatives of ethosuximide 6_ 8 at the same time. By remolding TiCl3 reduction of nitroolefins the yield of 2-methyl butyrolactone-2-acetaldehyde 4 from 3 can be increased to 88%. Anew method has been found to directly construct succinimide ring from 2-methyl butyrolactone-3-acetic acid 5. The procedure of this conversion is DCCcondensation of 5 and dry benzylamine in acetonitrile catalyzed by DMAPat 0 ℃ over night.
    Synthesis of the Polypyridine Ligands with Functional Groups
    JING Bing-Wen, WU Tao, ZHANG Man-Hua, SHEN Tao
    2000, 21(3):  395-400. 
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    Several new polypyridine ligands containing functional groups such as PO3H2, COOH, pHsensitive groups are synthesized and characterized with the purpose of developing new functional polypyridine complexes.
    Studies on the Quantitative Structure activity Relationships of Paclitaxel Analogues
    SHI Bing-Xing, LIANG Shi-Le, YUAN Ying-Jin, SUN Ming, MIAO Fang-Ming
    2000, 21(3):  401-406. 
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    Aseries of 98 paclitaxel analogues were investigated using the comparative molecular field analysis(CoMFA) and a high predictive 3D QSARmodel with a significant cross validated rcv2, conventional r2, and predictive rpred2. equaling to 0.714, 0.901, 0.812, respectively was obtained. It revealed that the changes of the C-13 side chain groups, especially 2'-OH, affected the activity significantly and others did less relatively. It also showed that the model was significant for the research and development of novel paclitaxel analogues to reduce the blind flight during drug designing.
    A Theoretical Study on the Formation of Hexa-coordinate Phosphorus Intermediate for Phosphoserine's Bio-mimic Reaction
    TAN Bo, ZHONG Ru-Gang, WAN Rong, ZHAO Yu-Fen, DAI Qian-Huan
    2000, 21(3):  407-411. 
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    The mechanism of phosphoserines bio mimic reaction involving the formation of hexa coordinate intermediate was studied by MNDOmethod. From literature, the intramolecular carboxylic phosphoric mixed anhydride 2 could be formed from starting material phosphoserine 1 by a non synchronous concerted reaction pathway and the transition state energies were 172 kJ/mol. In this paper, it was showed that the penta coordinate phosphorus 2 could in turn be converted into hexa coordinate phosphorus 3 by two steps. In the first step, the acidic proton in the intermediate 2 dissociated from P_O_Hbond to form 2', in which there is a weak hydrogen bond between O 1 on phosphorus and the hydroxyl group on the serine side chain. Then the hydrogen of the hydroxyl group could be transfered to O 1 on phosphorus through a hydrogen bond bridged transition state. In the second step, the oxygen O6 anion on the serine side chain could attack the phosphorus and the molecule geometry was changed into octahedral structure of hexa coordinate phosphorus intermediate 3. The hydrogen bond bridge structure lowered the transition state energy to 148. 5 kJ/mol. These results could be used to explain the formation of hexa-coordinate phosphorus intermediate and the co-participation of the carboxyl group and hydroxyl group of serine side chain during its bio-mimic reaction.
    Molecular Recognition Studies on Supramolecular Systems(一)—— Inclusion Complexation of the Novel Amino Acid Modified β-CDs with TNS
    JIN Lan, SUN Shi-Xin, LIU Yu 
    2000, 21(3):  412-414. 
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    The fluorescence spectra have been studied in phosphate buffer aqueous solution(pH=7.20) to give the stability constants( Ks) for the supramolecular system formed by L-Pro-β-CD(1), L-Leu-β-CD(2), and L-Ileu-β-CD(3) with TNS. The results obtained indicate that the binding ability of modified β-cyclodextrins(1) with TNSis larger than that of 2 and 3. One possible explanation is that there are different substitutes among the three modified β-cyclodextrins.The molecular binding ability is discussed from the size-fit concept between the host and the guest molecules. The results indicate that the substitute on the side arm attached to the edge of β-CDplays a crucial role in guest inclusion.
    The Studies on Spectrum of Tamol and Its Conjugate
    QIU Xiao-Hang, OUYANG Di, CHAO Hui, ZHOU Yong-Qia 
    2000, 21(3):  415-416. 
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    Being a promising anticancer agent, taxol draws more and more attention. This paper has studied the UVspectrum of taxol and fluorescence spectrum of BSA-taxol conjugate. Amethod of testing the modification radio is presented and the structure of the conjugate was discussed.
    Theoretical Research on the Electronic Structure, Spectra and Nonlinear Second order Optical Property of C59(C6H4OCH3)N
    FENG Ji-Kang, JIN Hong-Wei, REN Ai-Min, Sun-Xiu-Yun, Fu-Wei
    2000, 21(3):  417-420. 
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    We have made theoretical research on the substituted azafullerene C59 (C6H4OCH3)Nsysthesised from (C59 N)2 and to anisole with the INDOseries methods. The stable molecular configuration of C59 (C6H4OCH3)N has been obtained, and C59 (C6H4OCH3)Nis Cs symmetry. On the basis of the obtained geometry, the UV Vis and NMRspactra of C59 (C6H4OCH3)Nhave been calculated and discussed. The results are in good agreement with experimental results. The nonlinear second order optical susceptibility βμ of C59 (C6H4OCH3)Nhave been calculated too. The result shows that this molecule has a quite big nonlinear second order optical susceptibility.
    The Destabilization of π-Electron Delocalization in Cyclopentadiene──A Method of Separating out of Its π,π-like and σ Fragment Molecular Orbitals
    YU Zhong-Heng, XUAN Zheng-Qian
    2000, 21(3):  421-426. 
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    Aprocedure for separating out of π, π-like and σ fragment molecular orbitals(FMO) was established, and it provides for cyclopentadiene a complete FMObasis set in which all FMOs have correct electron occupancies. Based on our new method, the Morokuma energy partition provides, in the framework of ab initio SCF-MO computation at the STO-3G level, the various π and σ-energies associated with the inter-and intrafragment interactions. The π-electronic delocalization is destabilization in cyclopentadiene, and its delocalized π-system is also destabilized. In the case of benzene, its QMREis stabilizing. However, it is the σ-framework of benzene, rather than the π-system itself, to be strongly stabilized, revealing the benzene is σ aromatic. It should be emphasized that the σ-π space interactions, expressed in terms of the Coulomb Jσπ and exchange Ksp integrals, have significant effects on the molecular behaviour.
    The Effect of Cu Species on the Chemical State of Mo in the Mo/CuH-ZSM-5 Catalyst for Methane Non-oxidative Aromatization
    LI Shuang, WANG Dong-Yang, FU Ying-Huan, WU Peng, WU Tong-Hao, LIU Ying, ZHANG Chun-Lei, LIN Li-Wu, BAO Xin-He
    2000, 21(3):  427-430. 
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    The catalytic performance of Mo/CuH-ZSM-5 was compared with that of Mo/H-ZSM-5 for methane aromatization in the absence of oxygen. The Cu ions acted as promoters, and the activity and stability of catalysts for methane aromatization were enhanced to some extent. The fresh and reacted catalysts was studied by XRD, ESRand XPSmethods, and it is found that by the addition of Cu species, the reduction of MoO3 was suppressed and the Cu species itself was reduced. It is supposed that the Mo species with a higher oxidative state is responsible for the activation and conversion of methane.
    Self-consistent Crystal Orbital Study on Polyphosphorus and Polynitrogen Chains
    LI Cheng, HUANG Yuan-He, LIU Ruo-Zhuang, LIU Hua, ZHANG Jin-An
    2000, 21(3):  431-434. 
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    SCF-CNDO/2-COmethod is used to study the band structures and electronic properties of one dimensional polyphosphorus and polynitrogen chains(including the corresponding protonated chains). The polyphosphorus chains are expected to be semiconductors, but insulators for the polynitrogen chains. This prospect can not be changed by means of protonation for the corresponding chains. Since the lowest unoccupied bandwidth(LUBW) is much wider than the highest occupied bandwidth(HOBW) for the polyphosphorus chain, the mobility of electrons in LUband is much higher than that of holes in HOband. The conduction of the polyphosphorus chain should mainly depend on the conducting electrons in LUband. From a view of semiconductor materials, the polyphosphorus chain is favorable to form n type semiconductor with doping of donators.
    Theoretical Study on the Gas-phase Proton Transfer Reactions of the Formyl and Isoformyl Cations with Acetylene
    QU Zheng-Wang, DING Yi-Hong, LI Ze-Sheng 
    2000, 21(3):  435-438. 
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    The gas phase proton transfer reactions of the formyl and isoformyl cations (HCO+ and HOC+) with acetylene (C2H2) in gas phase have been investigated theoretically at the HF/631G(d,p), B3LYP/631G(d,p) and QCISD(T)/6311G(<2df,p)//B3LYP/631G(d,p) levels. The possible pathways leading to two dissociation products HC(H)CH++CO (a) and H2C=CH++CO (b) are probed. It is shown that high level electron correlation effect play crucial roles in studying the proton transfer process. The vertical attacks of the protons of HCO+ and HOC+ towards the π bond of C2H2 involving the respective complexes OC·HC2H2+ and CO·HC2H2+ are the most plausible mechanism for proton transfer, which may mainly lead to the π-protonated acetylene, HC(H)CH+. The higher exothermicity of the reaction of HOC++C2H2 and the lower stability of the involved intermediate suggest that HOC+ is more reactive than HCO+ for proton transfer reaction. Our calculated results agree well with the available experimental results and may be helpful for understanding the interstellar and combustion chemistry in which HCO+ and HOC+ are involved.
    Spectroscopy of Several β-Diketone Compounds and Their Tautomers
    CHU Qing-Hui, GAO Lian-Xun, WANG Dong-Mei, QI Ying-Hua, DING Meng-Xian 
    2000, 21(3):  439-443. 
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    Six β-diketone compounds, 1,3-bis(4-nitrophenyl)-1,3 propanedione (1) , 1-(4-nitrophenyl) 3-(3-nitrophenyl)-1,3-propanedione (2) ,-1,3-bis(3-nitrophenyl)-1,3-propanedione (3) 1,3-bis(4-amimophenyl)-1,3-propanedione (4) , 1-(4-amimophenyl)-3-(3-amimophenyl)-1,3-propanedione (5) and 1,3-bis(3-amimophenyl)-1,3-propanedione (6) were synthesized. Their structures were characterized by IR, UV Vis, fluorescence and NMRspectroscopy. The percentage of keto tautomer, enol keto equilibrium constant and enol tautomer ratio of them were also determined. The percentage of keto tautomer is increased in the order from compound 1 to 3 and decreased in the order from compound 4 to 6, which show the effect of substituent on the tautomer. The results of enol tautomer ratio of compounds 2 and 5 indicated that b-form of enol is slightly more favorable than its a form.
    Mechanisms of Kernel-forming and Growth of Diamond (111) Smooth Surface from Methyl
    LIU Jing-Yao, DING Yi-Hong, LIU Bo, DAI Zhen-Wen, PAN Shou-Fu
    2000, 21(3):  444-447. 
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    The AM1 semi empirical quantum mechanical method was used to calculate the mechanisms of kernel forming and growth on diamond (111) smooth surface by using methyl as gaseous growth species. The energies of reaction system in each step of kernel forming and growth reaction pathway were obtained. The results show that methyl can greatly contribute to the processes of kernel forming and growth of diamond on (111) smooth surface.
    Studies on the Alkylation of Isobutane with Butene over WO3/ZrO2 Strong Solid Acid(Ⅰ)──Effect of Preparation, Load of WO3 and Calcination Temperature
    SUN Wen-Dong, ZHAO Zhen-Bo, CHU Wen-Ling, GUO Chuan, YE Xing-Kai, WU Yue
    2000, 21(3):  448-452. 
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    Aseries of WO3/ZrO2 strong solid acid prepared under different conditions were studied. Their crystal structures, surface properties and acidities were determined by means of XRD, DTA TG, H2 TPR, Laser Raman and acidity measurements. The results revealed that ZrO2 in WO3/ZrO2 existed mainly in tetragonal phase, the addition of WO3 plays an important role to stablize tetragonal phase of ZrO2 and thus the catalyst had a considerable surface area. WO3 in WO3/ZrO2 was dispersed and crystalized in WO3 crystalite on ZrO2 surface and partly reacted with ZrO2 to form the bond of Zr—O—W, which acts as the strong solid acid site. The catalytic properties of WO3/ZrO2 strong solid acid for alkylation of iso-butane with butene under the different conditions were investigated. They had a better reaction performance than other strong solid acids, a parallel relationship could be drawn between the catalytic activity and the amount of acid sites as well as the acidic strength of the catalysts.
    A Dynamic Model of Potentiostatic Current Oscillation of Copper Electrodissolution in Acidic Chloride Solution
    LEI Jing-Lei, LUO Jiu-Li 
    2000, 21(3):  453-457. 
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    Amodel of current oscillation of copper potentiostatic electrodissolution in acidic chloride solution is proposed. It involves nonlinear steps dominated by couplings between chemical reactions and current. The linear stability theorem, as well as the bifurcation analysis is applied to discussing regimes of dynamic behavior in the parametric plane. Furthermore, both the polarization curve and the current oscillation curve are calculated respectively modeled as a stable steady state function related to the externally controlled potential and a stable limit cycle on state plane. The theoretical results are in good qualitative agreement with experimental observation reported in literature. It is concluded that the theoretical study of isoamplitude electrochemical oscillation can be achieved in light of Hopf bifurcation analysis.
    ESR Spin Trapping Studies on the Radicals Generated from Iron-containing System of Xathine Oxidase and Hypoxathine in the Presence of Saccharide Molecules
    QI Dan-Hua, LUO Gui-Min, ZHENG Ying-Guang, DONG Feng-Xia, YANG Tong-Shu
    2000, 21(3):  458-461. 
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    The free radicals generated from iron containing system of xathine oxidase and hypoxathine(Fe XO/HX) were directly detected by using spin trapping. It was found that not only O2-· and OH· but also alkyl or alkoxyl radicals(R· or RO·) were detected when saccharides such as glucose, fructose and sucrose were added into the Fe-XO/HXsystem. The amounts of R· or RO· were increased with the increase of saccharide-concentration added to the Fe-XO/HXsystem. The results showed that saccharide molecules were oxidized by the saccharide containing Fe-XO/HXsystem. R· or RO·has a long life time and they are liposoluble. Thus, they have more toxicity than hydrophilic O2-·and OH·because the active sites of biomolecules are closely related with lipophilic phase. It is worth mentioning that the results have provided an evidence for the hypothesis of "Eating excess sucrose facilitates aging".The R· or RO· radicals were effectively scavenged by selenium-containing abzyme, which displayed a powerful ability to antioxidize.
    Preparation of the Photocatalytic Antifogging Membrane and Its Hydrophilic Property
    LIU Ping, LING Lan, LING Hua-Xiang, FU Xian-Zhi 
    2000, 21(3):  462-465. 
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    Supported multicomponent membranes with photocatalytic antifogging property were prepared by the improved sol gel method. The influences of preparation and experiment conditions such as thickness of membrane, temperature and time of sintering, light source, and intensity of illumination on hydrophilicity of the membranes were studied by using XRD, AESand water-contact angle measurement. The results show that TiO2 crystal type and specific surface area of the membrane are the important factors affecting the hydrophilicity of the photocatalytic antifogging membrane. The water-contact angle is decreased with increasing the specific surface area and the content of anatase. Hydrophilicity of the membrane was also determined by thickness of membrane due to the amount of catalyst and efficiency of UVlight absorption. It was found that the hydrophilicity has a step-response to intensity of illumination. Sunlight illumination has a similar efficiency to the ultraviolet lamp for recovering and maintaining hydrophilicity of membrane.
    Fabrication of Supramolecular Nanotubes Based on Barbituric Acid and Melamine Derivatives
    LU Nan, LU Ran, WANG Ce, CAO Chang-Sheng, XIE Teng-Feng, LI Tie-Jin
    2000, 21(3):  466-468. 
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    Hollow supramolecular nanotubes have been fabricated by the self-assembling of 5-(4-N-methyl-N-tetradecyl aminobenzylidene)-2,4,6 (1H,3H)-pyrimidinetrione(AB1,14) and 4-amino-2, 6-didodecylamino-1,3,5-triazine (M12) in non hydrous chloroform. The nanotubes are 7 nm in diameter and about hundreds of nanometer in length. Their formation was realized by π-π aromatic stacking of the hexamers, which resulted from the interaction of three complementary hydrogen bonds between AB1,14 and M12. X-ray diffraction pattern indicated that the distance between the hexamers is 0.49 nm.
    IR Studies of CO Adsorption on β-Zeolite with Highly Dispersed CuCl2·2H2O Treated by Microwave
    ZHOU Qun, DING Hong, QIU Shi-Lun, PANG Wen-Qin
    2000, 21(3):  469-471. 
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    COadsorption on β-zeolite with highly dispersed CuCl2·2H2Owas studied by IRspectroscopy. The results of XRDand 29Si NMRindicate that CuCl2·2H2Ois highly dispersed into β-zeolite channel as a monolayer. The IRspectra of adsorbed COon the zeolites demonstrate that two distinct types of adsorption sites exist in the zeolites, i.e., cation and non cation exchange sites. Two simultaneous processes, solid phase ion exchange and molecular diffusion, are involved in the dispersion of CuCl2·2H2O.
    Preparation of Oil-soluble ZnS Nanoparticles
    CHEN Shuang, LIU Wei-Min
    2000, 21(3):  472-474. 
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    Surface modified ZnSnanoparticles were prepared in this work. Infrared spectroscopy(IR), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS) were used to investigate the structure, size, and morphology of the modified ZnSnanoparticles. It was found that the average diameter of the coated ZnSnanoparticles was about 4 nm, and the dispersion capacity and oxidative stability could be improved effectively by surface modification with DDP.
    Effect of Uniaxial Pressures on the Resistance of High Density Polyethylene/Carbon Black Composites
    SONG Yi-Hu, ZHENG Qiang, PAN Yi, YI Xiao-Su
    2000, 21(3):  475-479. 
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    The relationship between uniaxial pressures and resistance of high density polyethylene/carbon black(HDPE/CB) composites was studied. The results showed that there existed a critical pressure below which composite resistance decreased with the increase of pressure and above which resistance increased with the increase of pressure. Correspondingly, these behaviors were defined as negative and positive pressure coefficient of resistance in this work. There existed obvious electrical hysteresis during unloading procedures. Nonrecoverable resistance was found when pressures approached to zero. It was believed that the uniaxial pressures resistance relations were involved in the reformation and destructure of conductive network under pressures. Asimple piezoresistive model was proposed phenomenologically to explain the experimental results.
    Synthesis and Free-radical Ring Opening Polymerization of Macrocyclic Aryl Thioether Ether Ketone(sulfone) Oligomers
    QI Ying-Hua, CHEN Tian-Lu, LIU Sheng-Zhou, XU Ji-Ping
    2000, 21(3):  480-483. 
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    Two kinds of novel macrocyclic aryl thioether ether oligomers were synthesized by nucleophilic condensation reaction in high yields under pseudo high dilution condition. Acombination of 1H NMR, GPCand MALDI-TOF MSanalyses unambiguously confirmed the cyclic nature and their distributions. Macrocyclic thioether ether ketone oligomers can undergo facile melt ring opening polymerization(ROP) initiated by thiyl radical to give a high molecular weight polymer.
    Synthesis of α- Chloroacetyl Oligomer as Macroinitiator for ATRP
    LIU Bing, LIU Feng, LUO Ning, YING Sheng-Kang, LIU Qing
    2000, 21(3):  484-487. 
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    Chloroacetyl polystyrene macroinitiator was synthesized by anionic polymerization. The optimum conditions for the synthesis of chloroacetyl oligomer are as follows: acylating temperature is 60 ℃, acylating time is 24 h and chloroacetyl chloride is excess 5 fold for n-butyl lithium. The structure of α chloroacetyl polystyrene macroinitiator was characterized by IRand 1H NMR. Block copolymer, such as PSt-b-PMA, PSt-B-PBA, was synthesized by ATRPwith α-chloroacetyl polystyrene oligomer as macroinitiator and the structure of PSt-b-PMAwas characterized by 1H NMR.
    Film Formation of Monodispersed Polystyrene Latex at High Temperature
    WANG Li-Jun, YANG Zhen-Zhong, LIU Zheng-Ping, ZHAO De-Lu
    2000, 21(3):  488-490. 
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    In this paper, we discussed the drying behavior of monodispersed polystyrene latex at high temperature with particular attention to the morphological evolution during film formation process. At the beginning of the water evaporation, a skin film with some defects was formed at latex/air interface, water evaporated thereby in a constant rate. During this stage, a drying front advanced from the top film towards the bulk dispersion. Afte Rwards, most water was lost, and water evaporation rate was less than that of the initial stage. In this case, the whole system became immobile, and another drying front developed from the interior region outside the system. Two distinct boundaries between completely dried region and wet region corresponding to the opposite directions of the second drying front were found if the film peeled from the container bottom surface. Besides, some particular morphologies were found in the completely dried region, which was likely related to preferable coalescence among the particles induced by capillary force due to water evaporation.
    Melt Crystallization of Poly(ether ether ketone ketone) Under Strong Electric Field
    QIU Zhao-Bin, XIAO Xue-Shan, MO Zhi-Shen, YU Ying-Ning, WANG Xian-Hong, DONG Yuan-Da
    2000, 21(3):  491-492. 
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    In this paper, melt crystallization of poly(ether ether ketone ketone)(PEEKK) under strong electric field was investigated. In the crystal structure of PEEKK, the length of c axis was found to be 1.075 nm, increasing by 7% compared to that of PEEKKcrystallized without strong electric field. The molecule chains might take a more extended conformation through the opening of the bridge bond angles by increasing from 124° to 144° under strong electric field in the crystal structure.
    Cyclization in situ of Isoprene Polymerization Catalyzed by Nd-Al Bimetallic Complex
    DONG Wei-Min, YANG Ji-Hua, PANG Shu-Fen
    2000, 21(3):  493-495. 
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    Function of chloride and effect of various alkylaluminiums, Cl/Al molar ratio, solvents on cyclization in situ of isoprene polymerization catalyzed by Nd Al bimetallic complex were studied. The structure of cyclized products was characterized by means of IRand 1H NMR. The results indicated that in the course of isoprene polymerization with rare earth catalytic system, the function of alkylchloride introduced is terminating cis polymerization and generating cationic species with alkyl-aluminums to initiate cyclization in situ . Soluble cyclized polyisoprene was obtained with fragments of cyclopolyisoprene.
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