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Table of Content

    24 August 1997, Volume 18 Issue 8
    Articles
    A Study of Intramolecular Electron Transfer Process of Porphyrin-anthraquinone Under Photoinduction(Ⅱ)─Paramagnetic Resonance Method
    WANG Xing-Qiao, WANG Cong-Xiao, WANG Qing-Min, YU Lian-Xiang, CAO Xi-Zhang, MIN Chun-Zong, WANG Li-Ping
    1997, 18(8):  1241-1245. 
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    In this paper, the method of paramagnetic resonance was used to study the pro-cess of formation of ionic free radicals of a new type of porphyrin-anthraquinone compounds through intramolecular electron transfer under photoinduction at a low temperature and the effects of different porphyrin ligands, metal-porphyrin, organic bases axial coordination and solvents on the electron transfer were studied. The experimental results indicate that ESRsignal intensities of porphyrin and metal-porphyrin were increased with time and tend to be stable after 50 min. The signal intensities of PAQ are in the order:H2TDMAPPQ>H2(o-NH)PTriPPQ>H2(p-NH)PPQ, while signal intensity of ZnPAQis greater than that of the corresponding PAQ. The formation rate and quantum yield of ionic free group pair P+·-AQ-· for PAQand ZnPAQin the strong polar solvent(DMF) are lower than those in weak polar solvent(CH2Cl2). The axial coordination with piperidine and imidazole increased ESRsignal intensity of ZnTDMAPPQ, which played a promoting role for the charge separation ofZnPAQ. Furthermore, β-carotene may further enhance the charge separation of ZnTDMAP-PQwith positively charged side chain. Therefore, this kind of PAQcompounds are ideal ones for photosynthesis.
    Synthesis and Crystalline Structure of Cluster Co3(CO)73-S)[μ,η2-SCNC (O)C (R1) (R2)N (COR3)]
    CHENG Qing-Min, LIU Shu-Tang, HU Xiang, LIU Qi-Wang, XU Ying
    1997, 18(8):  1246-1250. 
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    Through the reaction of Co2(CO)8 with four thiohydantoins,(这里有图片19970802-1246-3.gif),four new sulfur-capped trinuclear cobalt carbonyl clusters (这里有图片19970802-1246-4.gif)[I: R1=R2=H;II: R1=H,R2=CH3, R3 =Ph; III: R1=R2=H, R3=CH3;IV: R1=R2=R3=CH3], were prepared and characterized by elementary analysis, IR, 1H NMRand MSspectroscopy. The crystal struc-ture of the cluster (这里有图片19970802-1246-5.gif)(IV ) was deter-mined by X-ray single crystal diffraction method.The crystal of the cluster is triclinic be-longing to space group P1 and the cell parameters are as follows:a=0.8456(3) nm,b=1.1534(3)nm, c=1.1990(4)nm;α=107.36(3)°, β=108.44 (5)°, γ=90.18(3)°;V=1.052(6)nm3,Z=2, F(00 0) =584, Dc=1.86g/cm3, μ=25.71cm-1,R=0.046,Rw=0.058. The molecule has revealed to have a pyrimidal Co3Sframework and contain a heterocyclic bridging bidentate ligand (这里有图片19970802-1246-6.gif)linked to the Co(1)and Co(2) atoms of the cluster by a cobalt-nitrogen and a cobalt-sulfur bond respectively.
    Thermodynamic Studies on N-Diacetic acid substituted tetraazamacrocycle and Its Lanthanide Complexes
    BI Jian-Hong, ZHAO Xiang-Da, NI Shi-Sheng, XIE Fu-Xin
    1997, 18(8):  1251-1254. 
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    The protonation constants of the macrocycle H2L(C-meso-meso-5, 12-diphenyl-7,14-dimethyl-1, 4, 8, 11-tetraazamacrocyclotetradecane-N, N"-diacetic acid) were determined by potentiometric titration in 0.5mol/L KCl solution at (25±0.1)℃, (30±0.1)℃ and (40±0.1)℃.The changes of enthalpy and entropy in the coordination reaction of H2Lwith H+ in the solution were given. The stability constants of the complexes of H2L with La3+,Nd3+, Pr3+, Sm3+, Eu3+, Gd3+, Dy3+ and Yb3+ were determined by the same method at (40±0.1)℃. The experiment results obtained were discussed.
    Synthesis, Characterization and Structure Determination of Yttrium Complex with Iminodiacetic Acid
    LI Jun-Ran, ZHOU Li-Ping, JIN Tian-Zhu, YU Kai-Bei
    1997, 18(8):  1255-1258. 
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    The title complex was synthesized and its crystal structure was determined by sin-gle crystal X-ray diffraction technique with a four circle diffractometer to give final R1 value 0.0509 and WR2 value 0.1337. The crystal is triclinic with space group P1 The unit cell parameters are: a=0.9254 (1)nm, b=0.9922(1) nm, c=1.0658(2)nm, α=71.481(10)°, β=77.950(10)°, γ=65.350(10)°, V=0.8401(2)nm3, Z=2, Dc=2.034g/cm3.The complex is a two-dimensional polymeric molecule.In addition, every yttrium atom is co-ordinated by four oxygen atoms from four iminodiacetic acid molecules and four oxygen atoms from water molecules.The coordination number of yttrium ion is 8 and the coordina-tion polyhedron is a distorted trigondodecahedron.
    A Study of the Interaction Between Titanocene Glycine Complex and DNA
    ZHANG Zhi-Gang, YANG Pin
    1997, 18(8):  1259-1261. 
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    The interaction between titanocene glycine complex and DNAhas been investigat-ed by UV-Vis spectra and fluorescence probe method. The results suggest that the complex forms an irreversible adduct with DNAin molar ratio 1:1, and induces the comformation changes of DNAat high ratio of the complex to DNA,leading to the disruption of DNAdu-plexical structure.
    Synthesis and Characterization of Lathanum Complex with 8-Hydroxyquinoline by Solid State Reaction
    LU Jing-Ci, CHEN Jun-Sheng, SU Qing-De, YONG Ke-Lan
    1997, 18(8):  1262-1264. 
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    Solid state reaction between La (Ac)3·3/2H2O and 8-hydroxyquinoline (Oxine)was studied at a low heating temperature. La (Oxine)3 was synthesized by one step solid state reaction at 60℃, and the product is characterized by elementary analysis, IR, XRD,photoacoustic spectra and flourenscence spectra. The influence of the temperature on solid state reaction was discussed.
    Studies on Retention Value Convergent Phenomenon for Homologous Series in High-Performance Liquid-phase Chromatography
    SUN Zhao-Lin, BAI Jian-E, LIU Man-Cang, HU Zhi-De, ZHOU Shan-Hua
    1997, 18(8):  1265-1270. 
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    Ageneral model was established to describe the convergent phenomenon of ho-mologous series on the basis of discussion about the factors affecting solute retention be-haviour. The regression analysis for 12 kinds of homologous series(38 groups of data) was completed in six different mobile phases and on eight stationary phases,respectively.The results indicate that the correlation coefficient r≥0.974, standard deviation SD≥0.05. The surface and the projection of these homologous series' retention values have been drawn in three and two dimension,respectively.Convergent phenomenon and its meaning are also dis-cussed based on these graphs. Asimple method for calculating the convergent point coordi-nates is derived by using the first partial derivative.
    Studies on Microwave-Carbon Reduction Method for the Treatment of Nitric Oxide
    ZHANG Da-Xin, YU Ai-Min, JIN Qin-Han
    1997, 18(8):  1271-1274. 
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    Anew method of treating nitric oxide (NO) was reported in this paper. The method adopted a microwave-carbon reduction technique without using any catalyst. The ef-fects of gas flow rate, reaction temperature, microwave power and microwave applying time on the reduction reaction between the activated carbon and NOwere discussed. The reaction efficiency of transforming NOinto N2 and CO2 in a way of applying microwave continuously was compared with that of applying microwave intermittently. The results indicated that the effects of microwave power, type of reactor and temperature-raising rate on reaction efficien-cy are significant. The reaction efficiency can be up to 98% when the microwave was applied continuously and the reaction products were examined.
    Studies on the Fluorimetric Molecular Recognition of Schiff Bases Containing Double Aromatic Guests with Water Soluble β-Cyclodextrin Cross-linking Polymer
    SU Xiao-Di, LIU Liu-Zhan, SHEN Han-Xi
    1997, 18(8):  1275-1280. 
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    The enhancing fluorescence action of Schiff's bases containing double aromatic guests using water soluble β-cyclodextrin cross-linking polymer was studied in this paper.It was found that the distance between the two aromatic guests would be an important factor for enhancing fluorescence action. The ability of molecular fluorescence emission would be only enhanced when there was three or four atoms between two aromatic guests. This steric selectivity showed that the β-CDpolymer would be possible to become a novel method for flourimetric molecular recognition of Schiff's bases containing double aromatic groups.
    Studies on Synergistic Extraction of Sc(Ⅲ)with HBTMPTP and Cyanex925
    WEI Zheng-Gui, LI De-Qian, WANG Chun, JIANG Zu-Cheng
    1997, 18(8):  1281-1285. 
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    The synergistic extraction of Sc (III) from H2SO4 solution with bis(2,4,4-trimethylpentyl)monothiophosphin acid (HBTMPTP, HL) and branched chain alkyl phos-phine oxide mixture (Cyanex 925, B) in n-hexane has been investigated. The results indicat-ed that synergistic effect was showed in low acidity(CH2SO4<0.25mol/L). The composition of the extracted complex of Sc (III) has been determined to be Sc (HL2)2B3(SO4)1/2 by the method of slope analysis.
    The Determination of Potentiometric Titration End-points by Using Wavelet Transform
    WANG Hong, PAN Zhong-Xiao, LIU Wei, ZHANG Mao-Sen, SI Sheng-Zhu, WANG Li-Ping
    1997, 18(8):  1286-1290. 
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    The methods of image processing and edge detection by wavelet transform were introduced into chemistry for determining potentiometric titration end-points.This method was used to deal with the experiment data derectly without introducing artificial error factors in calculation. The accuracy of calculation results can get to the experiment limit automati-cally, and the titration end-points can be determined easily by this method. Very satisfactory results were obtained in the calculation.
    Studies on the Various Refolded Intermediates of α-Amylase Denatured by Urea with High Performance Hydrophobic Interaction Chromatography
    BAI Quan, WEI Yin-Mao, GENG Ming-Hui, GENG Xin-Du
    1997, 18(8):  1291-1295. 
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    a-Amylase originally denatured with 8.0mol/Lurea and its re folded intermedi-ates were investigated by high performance hydrophobic interaction chromatography. Many kinds(at least 19) of its re folded intermediates were obtained and found to be relatively sta-ble, at least for a week, in their respective solutions of the mobile phase used. The result was further proved by the methods of electrophoresis, ion exchange chromatography and size exclusive chromatography. In addition, the difference between the molecular conformations of these intermediates was investigated by ultraviolet-absorption spectrum and fluorescence emission spectrum.
    Studies on Calixarene Polysiloxane Stationary Phases for Capillary Gas Chromatography
    ZHANG Wei-Ya, ZHANG Shao-Wen, ZHANG Chi, WU Cai-Ying, ZHONG Zhen-Lin
    1997, 18(8):  1296-1299. 
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    Two new kinds of calix [4]arene polysiloxane, cone bis (undecenyloxy)-p-tert-butyl calix [4]crown-5 polysiloxane (c-c [4]c5-pso) and partial cone 5, 11, 17, 23-tetra-tert-butyl-25, 27-diethoxy-26, 28-diundecenyl calix[4] arene polysiloxane(p-c[4]-pso), were syn-thesized and used as the stationary phases for capillary gas chromatography for the first time.They exhibit a good thermal stability and an excellent selectivity for alcohols,benzene series,halohydrocarbon,aromatic compounds,especially for substituted phenol isomers.The separation mechanism has also been investigated.
    A New Interface for Coupling Capillary Electrophoresis to Inductively Coupled Plasma Spectrometry
    MEI Er-Wen, Hideki Ichihashi, Shin-ichi Yamasaki
    1997, 18(8):  1300-1302. 
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    Anew interface for coupling capillary electrophoresis(CE) to inductively coupled plasma spectrometry(ICP-AES) was developed. The interface was independent .of the nebu-lizer, and can be easily connected with micro concentric nebulizer (MCN) and conventional pneumatic concentric nebulizer (CPCN). By CE-CPCN-ICP-AESand CE-MCN-ICP-AES,efficient separation of Cr3+ and Cr2O72-was obtained, and the sensitivity is satisfactory.
    Hemin as a Peroxidase Substitute in Mimetic Enzyme Immunoassay for Hepatitis B Surface Antigen
    ZHU Qing-Zhi, ZHENG Xue-Ying, LI Fang, XU Jin-Gou, LIU Feng-Hua, LI Wen-You
    1997, 18(8):  1303-1305. 
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    Anovel mimetic enzyme immunoassay method was developed for the determina-tion of hepatitis Bsurface antigen (HBsAg) in solution. Hemin, a horseradish peroxidase substitute, was used as a labelling reagent to catalyze the reaction of thiamine, a new fluoro-genic substrate, with hydrogen peroxide at pH 8.5. In the sandwich immunoassay,anti-HBsAg antibody was coated on a 96-well plate(polystyrene), which first reacted with stan-dard HBsAg solution, and then further reacted with the fixed amount of hemin-labelled anti-HBsAg. After the two-step immunoreaction, the immunochemically adsorbed hemin-anti-HBsAg conjugate moiety was determined by measuring the fluorescence produced in a solu-tion containing thiamine and hydrogen peroxide. The flourescence intensity was directly pro-portional to the concentration of HBsAg. The calibration graph for HBsAg was linear over the range 2.5-500ng/well with a detection limit of 2.5ng/well.
    3,3',5,5'-Tetramethylbenzidine(TMB)-H2O2-HRP Voltammetric Immunoassay for the Determination of IgE in Human Serum
    HE Ya-Nan, CHEN Hong-Yuan
    1997, 18(8):  1306-1308. 
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    Adifferential pulse voltammetric immunoassay associated with the TMB-H2O2-HRPfor the determination of IgEantibody was developed. The enzymatic reaction product produced by HRPcatalyzing the oxidation of H2O2 with TMBexhibits a sensitive voltammet-ric response at 0.10V(vs.Ag/AgCl) in pH 4.0 phosphate-citrate buffer solution. The de-tection limit of the present method for IgEantibody was 4.0IU/mL, which was four times lower than that obtained by traditional spectrophotometric ELISAprocedure. It has been ap-plied to the determination of IgEin human serum with satisfactory results.
    Target Transformation Factor Analysis Based on Calculated Most Different Spectra for Resolution of IR Spectra from Mixture System
    QU Jia-Xin, HE Xi-Wen, WANG Yong-Tai, YANG Wan-Long
    1997, 18(8):  1309-1311. 
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    Target transformation factor analysis(TTFA) based on the actual most different spectra (AMDS) could resolute the pure component spectra. But it depended on the con-struction of primitive mixture greatly. The new method that AMDSwere replaced by the cal-culated most different spectra(CMDS) overcome this restriction. It was applied in the simu-lated and actual systems and the results were satisfactory.
    Knoevenagel Condensation of 3,5-Dimethoxyphenylacetaldehyde with Ethyl Hydrogen Malonate
    ZHAO Ya-Jun, JIAO Yu-Guo, TANG Hui-Tong, ZHANG Pang
    1997, 18(8):  1312-1315. 
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    Knoevenagel condensation of 3,5-dimethoxyphenylacetaldehyde with ethyl hydro-gen malonate in pyridine-piperidine led to the isolation of two products. One is not the ex-pected 4-(3, 5-dimethoxyphenyl)-2-butenoate,but is its isomeric 3-butenoate which could not be equilibrated with its 2-isomer by a base like its parent 4-phenyl-2-and-3-butenoates.The other is 2', 4', 2", 4"-tetramethoxy-2, 3: 6, 7-dibenzo-9-oxabicyclo [3.3.1]nona-2, 6-di-ene which is formed by phenol-aldehyde condensation under the basic condition rather than usual dimerization brought about by Lewis acid catalysis.
    Molecular Recognition Study on Supramolecular System (Ⅻ)──Molecular Recognition of4-Substituted Phenols by Cyclodextrins and Binuclear Cu(Ⅱ) Complexes with Cyclodextrins
    LIU Yu, YOU Chang-Cheng, HAN Bao-Hang, LI Yu-Mei, LI Bin, CHEN Rong-Ti
    1997, 18(8):  1316-1320. 
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    The spectrophotometric titrations have been performed in aqueous solutions with different pHvalues at 25.0℃ to give the stability constants (IgKs) for inclusion complexa-tion of various 4-substituted phenols with α-, β- and γ- cyclodextrins and binuclear copper (II)-α, β-cyclodextrins complexes. The stoichiometry of the supramolecular complexes formed is 1:1 for all the host cyclodextrins and binuclear copper(II)-cyclodextrins complex-es inclusion complexation with various guest 4-substituted phenols.The molecular recogni-tion mechanism for 4-substituted phenols of the cyclodextrins and binuclear Cu(II) complex-es with cyclodextrins is discussed from the viewpoint of the size/shape-fit, multiple recogni-tion,induced-fit relationship between the host cavity and the guest molecules.The results obtained indicate that the binuclear Cu(II) complex with β-cyclodextrin possesses the spe-cial binding ability and molecular selectivity for 4-substituted phenols.
    Hydrolytic Metalloenzyme Activity of Zinc(Ⅱ) Complex of Tris (2-benzimidazylmethyl) amine
    CHEN Wan-Dong, ZHU Shou-Rong, LIN Hua-Kuan, LIN Chun-Chen, LIN Mei-Rong, CHEN Rong-Ti
    1997, 18(8):  1321-1324. 
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    The hydrolytic kinetics of p-nitrophenol acetate(NA) catalyzed by zinc(II) com-plex of Tris (2-benzimidazylmethyl)amine (NTB) has been studied. It was shown that the catalytic hydrolytic rate is of first-order to both zinc(II) complex and NAconcentrations.The second-order rate constant is kcat=0.12mol-1·L·s-1 (T=298K, I=0.10mol/L KNO3,0.02mol/L Tris buffer, 40% CH3CNaqueous solution).This is one of the most efficient hydrolytic metalloenzyme model compounds reported up to now. The increase of CH3CNcontents in the solution greatly decreased the hydrolytic activity of the nucleophiles.
    Synthesis and Biological Activities of 1-Alkyl-2-methyl-4 (5)-nitroimidazole Derivatives
    LI Run-Tao, CAO Sheng-Li, SUN Wan-Fu, CAI Meng-Shen
    1997, 18(8):  1325-1328. 
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    Seven α,ω-di-[2-methyl-4-nitroimidazolyl)]alkanes and twenty 1-alkyl-2-methyl-4-nitroimidazoles were synthesized with solid-liquid phase-transfer catalytic method. The yield for the most of compounds is more than 80% except a few compounds. The structures of the compounds were confirmed by IR,1H NMRand elementary analysis. The preliminary biological activity test shows that some of the compounds have certain anti-inflammatory,antibacterial, analgesic, sedative or anticerebral anoxia activities.
    Synthesis and Crystal Structure of Trihalostannane and Tungsten(molybdenum) Bonded Bimetallic Complexes
    HE Hai-Yang, XU Yu-Ming, WANG Ji-Tao, SUN Jie, KONG Xiang-Fu
    1997, 18(8):  1329-1332. 
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    The substitution reaction of CpM (CO)3SnPh3 or CpM (CO)3SnPh2X (Cp=C5H4CH3, C5H4COCH3;M=Mo, W; X=Cl, Br) with HCl or HBr yielded trihalo- or mixed trihalostannane tungsten(molybdemun) bonded bimetallic complexes, which were character-ized by elementary analysis, 1H NMRand IR. Crystals of complex Cl3SnW(CO)3C5H4·COCH3 are monoclinic, space group P21/c, a=0.7686(3)nm, b=1.2622(2)nm, c=1.6022(2)nm, β=102.13(2)°, Z=4, μ=97.45cm-1, V=1. 5197(7)nm3. The bond dis-tance of Sn-Wbond is 0.27361(8)nm.
    A New Iodolactone from Laurencia Majuscula
    SU Jing-Yu, XU Xiao-Hua, ZENG Long-Mei, WANG Chao-Jie
    1997, 18(8):  1333-1334. 
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    The genus of Laurencia has been well known for its production of terpenes and C15acetogenins, which are usually halogenated. Anew iodolactone (1) was isolated from the ethanol extract of the alga Laurencia majuscula, collected from the Xisha Islands in the South China Sea. Compound 1 is a kind of white solid, m. p. 63-64℃. The molecular for-mula was established by HREIMSas C26H47O4I. Generally, chlorinated or brominated metabolites are common in marine organisms. In contrast, iodosubstituted compounds are quite rare and interesting. The structure of 1 was elucidated by the spectral analysis, having a 3-iodo-δ-lactone structure moiety. Besides, two known compounds, cholesterol and n-e-icosanoic acid, were obtained as well.
    A Facile Total Synthesis of 6-Pentyl-α-pyrone
    ZHANG Chi, ZHANG Fang-Ning, WANG Xue-Chao, PAN Xin-Fu
    1997, 18(8):  1335-1336. 
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    6-Pentyl-α-pyrone (6PP), a natural product with a number of bioactivies, has been synthesized from furfural in a five steps route. The key step is the epoxidation of 2-furyl-pentylcarbinol (3) with NBSin a mixed solvent system THFand H2O(4: 1). The overall yield is 34%.
    Preparation and Catalytic Behaviour of Cr2O3-Pillared Tin Phosphate with High Surface Area
    TANG Yi, ZHANG Hua, WANG Xia, GAO Zi
    1997, 18(8):  1337-1342. 
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    The preparation of Cr2O3-pillared tin phosphate was studied in detail. The previ-ous method with two-step colloidization by propylamine and a great amount of NMe4Cl was innovated, and Cr2O3-pillared tin phosphate samples with a high surface area were prepared successfully through one-step colloidization by various ammes. The surface area of the sam-ples prepared reached 445m2/g, which was much higher than the value 380m2/g reported in literatures. After calcination at 400℃ the samples possess a prefect pillared structure and uniform slit-shaped mesopores with diameters between 1.7-5.0nm.The Crm2O3-pillared tin phosphate samples are weakly acidic, and are catalytically active for dehydration of iso-propanol and n-propanol. The cyclohexane dehydrogenation activity of the samples are high-er than that of a conventional Cr2O3 supported catalyst, showing that Cr2O3 in the pillared catalysts is in highly dispensed state.
    Ab Initio Theoretical Analysis of the Structure and Stability for Closo Boron Hydride B15H 152-(D3h)
    LI Qian-Shun, HU Xu-Guang, CAI Yu-Min
    1997, 18(8):  1343-1345. 
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    The geometrical structure of the doubly negative charged closo boron hydride B15H 152-(D3h) was optimized at the HF/6-31Glevel, and its energy properties and normal-mode vibrational frequencies were computed at the same level by using ab initio quantum chemistry calculation method. The calculated results show that the structure would be in-deed a stationary point on its HF/6-31Gpotential hypersurface and the cluster could be pre-dicted to be both chemically and kinetically stable.
    Quantum Chemical Studies on the Structures and Spectra for the Addition Product HC60CH2C6H5
    CHEN Zhong-Fang, TENG Qi-Wen, WU Shi, PAN Yin-Ming, ZHAO Xue-Zhuang, TANG An-Chin, FENG Ji-Kang
    1997, 18(8):  1346-1349. 
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    The INDOseries methods have been used to study the structures for the two kinds of isomers, which are 1, 2-addition and 1, 4-addition of HC60CH2C6H5. It is indicated that 1,2-HC60CH2C6H5 has Cs symmetry, while 1,4-HC60CH2C6H5 has no symmetry. Fur-thermore, the total energy of 1, 2-isomer is higher than that of 1, 4-isomer. The electronic spectra for both isomers have been calculated based on the optimized geometries and the rea-son for the red-shift of the spectra has been discussed.
    Studies on Stabilities and Electronic Polarizabilities of Polyacence Homologue Substituted by Cl
    WANG Rong-Shun, HUANG Zong-Hao, HUO Yu-Qiu, SU Zhong-Min, WANG Xiu-Jun
    1997, 18(8):  1350-1352. 
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    In this paper, the quantum chemistry CNDO/2 introduced with external electric field perturbation was used to calculate the electronic polarizability of polyacence homologue substituted by chlorine, which comprises seven structures. Their energies were obtained by using AM1 method. Their stability, energies and changing regulation of electronic polariz-ability with the increase of structure unit were compared with each other.
    A New Scheme for Determination of Atomic Charges and Bond Charges in Large Molecules
    WANG Chang-Sheng, SUN Ren-An, YANG Zhong-Zhi
    1997, 18(8):  1353-1355. 
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    On the basis of density functional theory and electronegativity equalization princi-ple, a new scheme has been developed for determination of atomic charges and bond charges in large molecules. In the new scheme, the molecular electron density ρmol(r) is partitioned as(这里有图片)<19970829-1353-1.gif> where ρα(r) and ρα-β(r) are the electron densities located on the atom α and bond α-β, respectively. The parameters A, B, Cand Dare the valence-state electronegativity and valence-state hardness. They are obtained by calibrating through model molecule calculations and are transferable and consistently usable for calculating the charge distributions in large molecules. The new scheme is tested through determination of atomic charges and bond charges in several large molecules. It has been shown that the re-sults of atomic charges and bond charges obtained by the new scheme dovetail those obtained by ab initio method very well. In addition, the new scheme presented here has the advantage of simplicity, rapidness and easy perform as well, so that it provides an efficient and practi-cal method for calculation of the charge distribution for a macromolecular system.
    STM Studies of C60 Coalescence Induced by UV Radiation
    TANG Zi-Chao, CAI Xiong-Wei, MAO Bing-Wei, HUANG Rong-Bin, ZHENG Lan-Sun
    1997, 18(8):  1356-1357. 
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    C60 molecule was adsorbed on the Au(111)surface and irradiated with UVlight.The coalescence under the UVradiation was followed by STMin situ. According to the STMobservation, the coalesced products have larger cages and finally form a film.
    Studies on a Conducting Langmuir-Blodgett Film Based on a Non-amphiphilic Tetrathiafulvalene
    LI Hong-Qi, ZHAO Sheng-Min, LIU Dan, TAN Gan-Zu, YU Xian-Da
    1997, 18(8):  1358-1360. 
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    Anovel mixed Langmuir-Blodgett(LB) film based on a 1:1 (molar ratio) mixture of a new non-amphiphilic tetrathiafulvalene (TTF) derivative dibenzylthio-dimethylthio-te-trathiafulvalene and arachidic acid (AA) was constructed and characterized by FTIR, UVspectra and X-ray diffraction. Measurement of conductivities of the LBfilms relating to the number of layers at room temperature showed that the conductivity of the films decreased with the increasing of layer number. After iodine doping the conductivities of the LBfilms increased by 102-103 magnitude compared with those before iodine doping and reached the maximum 2.5×10-3S/cm due to the formation of a new conducting phase, which was demonstrated by FTIRand UVspectral analyses. The result from X-ray diffraction indicates that the LBfilm has an ordered lamellar structure with a thickness per layer of 2.32nm.
    Ab Initio Calculation Study on Vibrational Spectra of Bis (C-p-carboranyl) (C2B10H11)2
    ZHANG Ming-Yu, YU Wei-Zhou, ZHOU Jian-Wei, SUN Chia-Chung
    1997, 18(8):  1361-1363. 
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    Geometrical optimization and theoretical calculation of the vibrational spectra have been performed for his(C-p-carboranyl) (C2B10H11)2 by using Gaussian 94 program at STO-3Gand 6-31Gbasis sets respectively. The optimization bond lengths are in agreement with X-ray experimental values. The calculated results show that in the title compound two icosa-hedral carboranyl cages seem rigid and the D5d arrangement is more stable than the D5h ar-rangement. The assignments have been made on the basis of analysis of vibrational mode.The carboranyl cage can be regarded as a pseudoatom. Raman line at 250cm-1 correspounds to the quasidiatomic molecule vibration.
    Studies on A New Catalytic System for Heterogeneous Carbonylation of Methanol to Methyl Formate
    LI Hai-Yan, ZHOU Jin-Mei, LIN Guo-Dong, ZHANG Hong-Bin
    1997, 18(8):  1364-1366. 
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    By using zeolite-supported alkali methoxide liquid-film catalysts, such as KOCH3-PEG/NaZSM-5(or NaY), the heterogeneous catalytic carbonylation of methanol to methyl formate was realized in a fixed-bed continuous flow reactor. Under the reaction conditions of 353 K,1.0 MPa, feedgas composition of CO/CH3OH=6.48(molar ratio) and GHSV=11160h-1, the STYof MFreached up to 1900mg/(h·gcat.), with selectivity to MFat 100%.The experimental results indicated that methoxide anion CH3O- was crucial catalyti-cally active species. The role of the additive polyethylene glycol(PEG) in generating a liquid-film environment, in which the carbonylation reaction would take place, is important,espe-cially in the case of supports with large pore-diameter as SiO2. However, in the case of some support materials with abundant micropore structure such as ZSM-5 or Y-type zeolite, it is probable to design and select appropriate reaction conditions(mainly, temperature and partial pressure of methanol in feedstream) to generate directly liquid-film of methanol by means of the "capillary condensation effect", as a consequence, addition of PEGmay be cut down, or even, avoided.
    Synthesis and Characterizations for (η2-C60) [Pt(PPh3)2]8
    CHENG Da-Dian, ZHUANG Yan, WU Zhen-Yu, YANG Shi-Yao, LIN Yong-Sheng, ZHAN Meng-Xiong, ZHENG Lan-Sun
    1997, 18(8):  1367-1368. 
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    Metal complex of buckminsterfullerene, (η2-C60)[Pt(PPh3)2]8,has been synthe-sized for the first time. It has been characterized by IR, XPSspectra as well as elementary analysis. The results show that the number bonded Pt(PPh3)2 to C60 is 8.
    Analog Thermogram Method(Ⅲ)──Reversible Reactions
    ZHANG Yuan-Qin, ZENG Xian-Cheng, HU Qi-Shan, MENG Xiang-Guang, TIAN An-Min
    1997, 18(8):  1369-1371. 
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    According to the theoretical bases of thermokinetics and analog thermogram method, a general analog thermogram method for several types of reversible reactions, with which the rate constants of forward and backward reactions and equilibrium constant can be calculted from the same thermogram simultaneously, has been proposed in this paper. The thermokinetics of the reactions of nitroethane with ammonia at 15℃ and 25℃ and with tris (hydroxymethyl)aminomethane at 15℃ and 30℃ have been studied with this method,re-spectively. The results of rate constants and equilibrium constants calculated with this method are in agreement with those in literatures. Therefore, the analog thermogram method for the reversible reactions is believed to be correct.
    Studies of Active Oxygen Species on the Surface of Rare Earth Oxide Catalysts for Oxidative Coupling of Methane
    XIE Wei-Guo, LU Shao-Jie, QIU Fa-Li
    1997, 18(8):  1372-1374. 
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    The active oxygen species on the surface of additive/rare earth oxides (RE2O3)catalysts have been investigated by means of XPS, O2-TPDand XRD. The results indicate that there exist Oand O2- species on the surface of the catalysts at low temperature. The performance of the catalyst is dependent on the concentration of Ospecies on the catalyst surface. It is suggested that the O- species formed from Ospecies at high temperature is active oxygen species for OCMreaction.
    Fourier Transform Infrared Photoacoustic Spectroscopy of Tetra-(para-hydroxyphenyl) Porphyrin Complexes
    SHI Tong-Shun, AN Qing-Da, XU Chun-Fang, LIU Guo-Fa, TENG Yong-Fu, QI Xiang-Li, YU Lian-Xiang
    1997, 18(8):  1375-1377. 
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    The Fourier Transform infrared photoacoustic spectra of tetra-(para-hydro-xyphenyl) porphyrin and its Cr(III), Mn(III), Fe(III), Co(II), Ni (II), Cu (II) and Zn(II) complexes in the range 3700-200cm-1 were measured and investigated. There exist intermolecular hydrogen bonds in the porphyrin and its complexes. The vibration coupling between the M-Nstretching and the porphyrin ring deformation appears at 250cm-1. The band at 316cm-1 is stretching vibration of M(III)-Cl. Metal sensitive bands were found at about 1550, 1350, 1076, 1000 and 250cm-1.
    Studies on the Specific Interaction Between the Model Polymer of Polyurethane Hard-segment and Poly(styrene-co-acrylonitrile)
    ZHU Zheng-Tao, ZHANG Yan, XIE Jing-Wei, JIANG Ming
    1997, 18(8):  1378-1383. 
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    In this paper, the miscibility in the blends composed of the model polymer(HM)of polyurethane hard segment and poly(styrene-co-acrylonitrile) (SAN) has been investigat-ed with DSCphysical aging and FTIRpeak resolution and fitting techniques. It is found that the blend is miscible due to the specific interaction between the components and addition of SANweakens the hydrogen bonding between carbonyl and amine groups in HM. The experi-mental results provide a basis for understanding the specific interactions between the polyurethane and SANblends.
    Kinetic Study of Seeded Emulsion Polymerization of Vinyl Acetate
    GUAN Rong, Gilbert R. G.
    1997, 18(8):  1384-1387. 
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    Aseries of seeded emulsion polymerization of vinyl acetate have been carried out using a dilatometer with a infrared monitor and a computer recording system in the initiator concentration range from 5.030×10-5mol/Lto 1.002×10-3mol/L. Due to the polymeriza-tion started from the interval II, the effect of the particle growth on the rate parameters has been avoided. Based on the experiment data of conversion vs time, we got the polymerization rate in quasi-steady state, and then calculated the entry rate coefficient ρ, exit rate coeffi-cient k and kpn. The results showed that the polymerization rate, ρ, k and kpn increased lin-early with increasing initiator concentration. Also, kpn is linear to the polymerization rate.
    Immobilization of α-Chymotrypsin and its Application to Resolution of DL-Phenylalanine
    LIU Li-Jian, YANG Ping, ZHUO Ren-Xi
    1997, 18(8):  1388-1392. 
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    α-Chymotrypsin has been immobolized on porous silica beads. The activity,opti-mum temperature and pHof the immobilized chymotrypsin as well as its Micllaelis constant have also been determined. its stabilities to heat, acid, base, methanol and urea are in-creased remarkably. It has been applied to resolving DL-phenylalanine continuously more than two months with good performance. L-Phenylalanine is obtained in a yield of 90%, and its optical purity reaches as high as 96%.
    Studies of Catalyzed Reaction Mechanism Between Co-polyether (THF/EO) and N-100 by NMR (Ⅰ)──Interaction and Complex Formation Between Reactants and Catalysts
    LUO Shan-Guo, ZHANG Jian-Guo, TAN Hui-Min, DONG Han-Jiang, WU Yi-Jie, PEI Feng-Kui
    1997, 18(8):  1393-1397. 
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    To elucidate the mechanism of the catalyzed reaction of co-polyether (EO/THF)with N-100, the interaction and complex formation between reactants and catalysts were in-vestigated by means of NMRspectroscopy. It is shown that the resonance peak of isocyanate carbon splits into two parts when the solutions of N-100 and co-polyether were mixed. The disappearing of proton resonance peak of hydroxyl group in NMRspectra when dibutyltin di-laurate(DBTDL) were added to the copolyether(THF/EO) solution indicates the complex formation. This interaction appears to be a bonding of tin to the oxygen of hydroxyl and make the hydrogen of the hydroxyl group very mobile and active, then exchange with other protons. In the case of triphenyl bismuth(TPB), the high field shift and intensity enhance-ment of proton peak were observed, which suggest a nucleophilic attack of the bismuth to the hydroxyl hydrogen.
    Progress in Hyperbranched Polymers
    SHI Wen-Fang, HUANG Hong
    1997, 18(8):  1398-1405. 
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    Hyperbranched polymers are a type of dendritic macromolecules which constitute a novel class of highly branched polymers with a multitude of end groups.Because of their highly branched three-dimensional and sphere-like molecular architecture,hyperbranched polymers have shown to exhibit the properties very different from those of their linear ana-logues,such as low viscosity, no inter chain entangling and high solubility. Hyperbranched polymers have a multiplicity of uses ranging from adhesive improvers and viscosity modifiers to applications in agriculture, perfumes and pharmaceuticals. This article discussed the prop-erties and characterization of hyperbranched polymers and reported work on hyperbranched polymers.The monomers used in synthesis and resulting polymers are discussed in details.The intention of this article is to rise interest in this field.