Chemical Research in Chinese Universities

Studies on the Redox Properties of Rare Earth Heteropoly Tungstoarsenate K₁₇[Ln(As₂W₁₇O₆₁)₂]·xH₂O

LIU Jing-fu, WANG Guang, ZHAO Ben-liang

1993, 9(3): 175-180.

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The redox properties of K₁₇[Ln(As₂W₁₇O₆₁)₂](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.

Synthesis and Luminescence Study of Europium Complexes with Carboxylic Acid and 1,10-Phenanthroline Ligands

QIAN Dong-jin, ZHANG Shu-zhen, CHEN Zhong, J. Van Houten

1993, 9(3): 181-187.

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A series of euroPium(Ⅲ)eomPlexes with earboxylie aeids andl,10-Phenanthro-line:Eu(L)₃:·phen·xH₂O,where L-formate,3-hydroxy-4-metlloxybenzoate,4-methoxybenzoate,4-ehlorophenoxyaeetate,and diphenylaeetate,were synthesized and characterized by elemental analysis,UV spectrum,IR speetrum and melting point.IR data confirmed that europium is coordinated with O donor atoms in carboxylic acid and N donor atoms in 1,10-phenanthroline.A strong ligand-loealized absorption at 270 nm led to a series of metal-centered emission bands between 580 and 710 nm as-signed to ⁵D₀-⁷F_0.1.2.3.

Synthesis and Characterization of Binuclear Lanthanide Complexes with Macrocyclic Schiff Base Derived From 2,6-Diacetylpyridine and 1,3-Diamino-2-hydroxypropane

ZHENG Hui, YAN Shi-ping, CHENG Peng, LIAO Dai-zheng, JIANG Zong-hui, WANG Geng-lin

1993, 9(3): 188-193.

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Nine homobinuclear lanthanide complexes with macrocyclic Schiff base were prepared by condensing 2, 6-diacetylpyridine and 1, 3-diamino-2-hydroxypropane in the presence of template lanthanide metal ions. These complexes were characterized by elemental analysis, IR, molar conductance and magnetic susceptibility. The variable-temperature magnetic susceptibility (4-300 K) of complexes of Gd(Ⅲ) and Dy(Ⅲ) was determined. A satisfactory fit to theoretical curve derived from spin Hamiltonian operator was obtained using least-squares method. The exchange interaction parameters are J=-0.26 cm^-1, g=1.98 and △=0.06 cm^-1, Z.J'=-0. 21 cm^-1,g'=1.33 for Gd(Ⅲ) and Dy(Ⅲ), respectively. The results indicate a very week antiferromagnetic interaction between Gd(Ⅲ)-Gd(Ⅲ) and Dy(Ⅲ)-Dy(Ⅲ) ions.

Synthesis, Crystal Structure and Thermoanalysis of o-vanillin-ethylenediamine Schiff Base Copper(Ⅱ) Complex

LIU De-xin, CUI Xue-gui, LI Shu-Ian, LI Xiao-yan, SUN Hong-jian

1993, 9(3): 194-200.

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The crystal structure of the title compound [Cu (o-vanillin-ethylenediamine) (H²O)] is described. The complex crystallizes in the orthorhombic system, space group Pbn2₁ with formula = CuC₁₈H₂₀N₂O₅, cell dimensions are: a = 0.7490(3) nm, b = 0.9256(2) nm, c=2. 4691(6) nm, V=1.712 nm³, Z = 4, D_c=l.51 g/cm³. The kinetics of thermal decomposition of the complex was studied under the non-isothermal condition by TG. Kinetic parameters were obtained from the analysis of the TG, DTG curves by integral and differential methods. By comparison of the kinetic parameters, the most probable mechanism function is f(α) = (3/2) (1-α)[-ln(1-α)]^1/3, and the mathematical expression for the kinetic compensation effect is lnA = 0. 201E+0. 531.

The Crystal Structure of Isosteviol

XUE Jie-you, TANG Shi-xiong, CAO Yu-rong, WANG Xiao-lan, WANG Ru-ji, WANG Hong-gen, LU Xiang-jun

1993, 9(3): 201-207.

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The title compound was prepared and its crystal structure was determined using X-ray crystallographic method. The crystal is orthorhombic, space group is P2₁2₁2₁ with a= 1. 1114(2) nm, b=1.7677(3) nm, c=1.8312(3) nm; Z=8. The geometric structure and conformation of the title compound obtained by MMX molecular mechanics calculation are in agreement with those obtained from X-ray determination.

Characteristics of Analyte Ionization in Low Power Microwave Plasma Torch

ZHANG Han-qi, LIU Xiao-jing, YU Ai-min, JIN Qin-han

1993, 9(3): 208-213.

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The ionization characteristics of the analytes in a low power Ar microwave plasma torch (MPT) was studied. The influence of forward microwave power, the flow rate of carrier gas and matrix element on the degree of ionization were observed. The axial profiles of the degree of the ionization of some elements were determined. The experimental results are very important for developing the new analytical source——microwave plasma torch (MPT).

The Effect of the Oxygen Preadsorption on the Adsorption of Nitric Oxide on Mo (111)

WANG Guo-Jia, K. B. Lewis, G. A. Somorjai

1993, 9(3): 214-219.

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The adsorption of nitric oxide adsorption on clean Mod(111), Mo(111)/O₂-(4×4), Mo(111)/O₂-(1×3), Mo(111)/O₂-(112) facets and Mo(111) oxide surfaces was studied. Mass 28 (N₂) desorption spectra show two high temperature peaks at approximate 1030 (β₁) and 1200K (β₂). For NO exposures less than 0. 1 L only the β₂ peak was observed. At higher exposures, the β₁ peak appeared and small amounts of N₂O as well as NO desorbed. The preadsorption of oxygen blocked the β₁ desorption partially on the (4×4) and (1×3) surfaces and fully on the (112) facet and oxide surfaces. In addition, the β₁ desorption peak shifted to higher temperatures with increasing oxygen preexposure.

Synthesis and Crystal Structure of trans(N)-(1,10-Phenanthroline)-bis (DL-Al aninato)-Cobalt(Ⅲ) Chloridetrihydrate

YE Bao-hui, ZENG Tian-xian, HAN Ping, JI Liang-nian

1993, 9(3): 220-224.

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The title compound was synthesized by the reaction of cis-[Co(phen)₂Cl₂]Cl·3H₂O with DL-alanine at pH = 8, and isolated using a column chromatographic method. Its crystal structure was determined. The crystal structure belongs to mono-clinic system, space group P2₁/c, with a = 0. 9549(6) nm, b=2.3746(8) nm, c= 1.0782(4) nm, β=114.13(3)°, Z = 4, D_c= 1. 50 g/cm³. The final refinement converged to R = 0. 047 for 3246 independent observed reflections. In the octahedral coordination sphere formed by the cobalt atom and the coordinate atoms, N, O of DL-alan-inato ligands are in the configuration of trans-N,N form.

Surface Properties of Cu Doped La-Ni Intermetallic Compounds

Baisheva R. G., Ibgasheva R. Kh., ZHEN Kai-ji

1993, 9(3): 225-230.

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A series of Cu-doped La-Ni intermetallic compounds(LaN_5-xCu_x, x = 0-4) was studied. The bulk structure and surface composition of the samples were detected before and after they were used as catalyst for nitrobenzene hydrogennation. The catalytic properties of the intermetallic compounds depend on the surface region composition, especially on the valence of the metal ions.

Kinetic Studies of Electrochemical Oxidation of 1,3-Benzenedithiol

XUE Kuan-hong, ZHOU Yi-ming, YANG Hui, H. S. Lee, X. Q. Yang, J. McBreen, T. A, Skotheim

1993, 9(3): 231-239.

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The electrochemical oxidation of 1, 3-benzenedithiol was investigated in a 0. 100 mol/L tetrabutylammonium perchlorate/acetonitrile electrolyte. The electrochemical techniques used were potential sweep, bulk electrolysis, rotating disc and the potential step method. The combination of the techniques yielded the number of electrons transferred per molecule, the reaction order, the transfer coefficient, the diffusion coefficient and concentration of dithiol anions, the standard heterogeneous rate constant as well as the formal potential and equilibrium constant of the preceeding dissociation reaction. This paper also illustrates the methods for studying the electrode kinetics of reactions which (a) involve a chemical reaction preceeding the electron-transfer process, (b) have insoluble polymer products, and (c) are totally irreversible.

Determination of Three-Dimensional Structures of Oridonin in Solution by NOESY Spectrum and Molecular Mechanics Calculation

YANG Yan-wu, JI Ang, HE Bing-lin, XU Xiao-long, QIU Jian-qing, WANG De-hua, QIAN Bao-gong, ZHAO Qing-zhi

1993, 9(3): 240-245.

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The phase sensitive NOESY spectrum of oridonin was treated using Full Relaxation Matrix Analysis(FRMA) approach, and the cross relaxation rates of proton pairs were obtained by diagonalizing the NOE matrix of oridonin. The inter proton distances were calculated according to 1/r_ij⁶ ∝σ_ij. The three-dimensional structure of oridonin in solution was calculated by the combination of WUPH, WUPH-S method with molecular mechanics minimization on the basis of NMR experiment.

Studies on Combination of Flow Injection and Microwave Plasma Torch-Atomic Emission Spectrometry

YE Dong-mei, ZHAO Jing-hong, ZHANG Han-qi, JIN Qin-han, DONG De-fan

1993, 9(3): 246-247.

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Electrochemical Studies on the Photolysis of Iron-Arene Complex Photoinitiator

CHEN Yong-lie, CHEN Xu-dong

1993, 9(3): 248-250.

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