Table of Content

24 January 1996, Volume 12 Issue 1

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Articles

Syntheses and Magnetism of μ-1, 3, 5-Benzenetricarboxylato Trinuclear Manganese(Ⅱ) and Nickel (Ⅱ) Complexes

SHI Jing-min, LIAO Dai-zheng, CHENG Peng, JIANG Zong-hui, MIAO Ming-ming, WANG Geng-lin

1996, 12(1):  1-5. 

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Two new manganese(Ⅱ) trinuclear complexes and two new nickel (Ⅱ) trinuclear compIexes, namely, [Mn₃(BZT)(Phen)₆] (ClO₄)₃(complex 1), [Mn (BZT)· (Nphen)₆] (ClO₄)₃(complex 2), [Ni₃(BZT) (Phen)₆] (ClO₄)₃· 5H₂O (complex3) and [Ni₃(BZT) (Nphen)₆] (ClO₄)₃(complex 4) (BZT=1, 3, 5-benzenetricarboxylato, Phen=1, 10-phenthroline, Nphen=5-nitro-1, 10-phenanthroline)have been synthesized. The complexes were characterized using elemental analysis,IRand electronic reflection spectra. These complexes are proposed to have extended 1, 3, 5-benzenetricarboxylato-bridged structure and to consist of three manganese (Ⅱ) or three nickel(Ⅱ). The X-band ESRspectra of the complex 1 and complex 2were recorded at room temperature. The variable-temperature magnetic susceptibilities of complex 1 and complex 3 were measured over 4. 2-300 K. According to experimental results of the variable-temperature magnetic susceptibility, the magnetic interaction between the paramagnetic centers is too weak to be detected using the usual magnetic susceptibility technique.

Studies of Mixed-valence Compounds(Ⅰ)──In-Situ FTIR and UV-Visible-Near-IR Spectroelectrochemical Studies of Mixed-valence Isopolyanion Mo₆O₁₉^3-in Aprotic Media

SUN Hao-ran, YANG Guo-yu, XU Jia-ning, XU Ji-qing

1996, 12(1):  6-9. 

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The mixed-valence isopolyanion Mo₆O₁₉^3-was investigated by means of cyclic voltammographic, in-situ FTIR and UV-Visible-Near-IR spectro-electrochemicalmethods in aprotic media. The experimental results indicate that the Mo₆O₁₉^3-was formed whereafter Mo₆O₁₉^3-was reduced, (E^0'=- 0. 690 V, n=1). The characteristic absorptions of Mo_{6O19^3-are 500 nm, 900 nm and 1100 nm in UV-VisibleNear-IRspectrum and 940 cm^-1in IRspectrum.}

Sensitized Luminescence of Rare Earths

SI Zhi-kun, HU Jing-tian, JIANG Wei, ZHU Gui-yun, LI Shu-hua

1996, 12(1):  10-15. 

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The enhancement effect on the fluorescence intensities of an Eu³⁺(or/and Sm³⁺)-thenoyltrifluoroacetone (TTA)-dibenzo-18-crown-6 (18-C-6) system and Eu ³⁺(or /and Sm³⁺) -benzoyltrifluoroacetone (BTA)-cetyltrimethylammonium bromide (CTMAB) system by dysprosium has been studied. In the presence of enhancing ions, the fluorescence intensities of the above systems were enhanced by a factor of about 40-150, respectively. The above systems were used for the determination of europlum or/and samarium in rare earths oxides and gave satisfactory results.

Construction of Mediated Amperometric Bienzyme Glucose Sensor

SUN Chang-qing, DU Wen-yuant, GAO Qian, XU Hong-ding

1996, 12(1):  16-21. 

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A bienzyme glucose sensor with 1, 1' -dimethylferrocene(DMFc) as an electron transfer mediator is described. Using nafion, DMFc was coated on a glassy carbon electrode (GCE) surface, horseradish peroxidase (HRP) and glucose oxidase (GOD) were then immobilized on the DMFc/Nafion film, forming a GOD/HRP/DMFc/Nafion-modified electrode. The characteristics of the sensor can be shown by cyclic voltammetry and constant potential measurements. The sensor responded fast to glucose, the time required to reach 95 % of the steady-state current was less than 30s. The sensor displays a sensitive catalytic current response to glucose and could be operated at a potential range in which the oxidation of common interfering species,such as ascorbic acid and uric acid, does not occur. The sensor is stable for 31 days and detection limit is 2 μmol/L.

Oscillation Conditions for An Electrode-separated Piezoelectric Sensor in Electrolyte Solution

SHEN Da-zhong, KANG Qi, YAO Shou-zhuo

1996, 12(1):  22-31. 

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Based on the needs of the oscillation equation and frequency stability, three oscillation conditions are proposed and have been experimentally verified for an electrode-separated piezoelectric sensor (ESPS) in electrolyte solutions. The present paper covers the dependence of the minimum cell constant needed for the ESPS on solution conductivity. The oscillation conditions of the classical liquid piezoelectric sensor are discussed. The "cease-to-oscillate" frequencies of the ESPS were measured.

Determination of Carbon by Means of Microwave Plasma Torch Atomic Emission Spectrometry

ZHANG Han-qi, YUAN Xiang-lin, YE Dong-mei, ZHAO Xiao-jun, JIN Qin-han, ZHU Zhi-ping

1996, 12(1):  32-36. 

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The determination of carbon by means of microwave plasma torch atomic emission spectrometry(MPT-AES) was studied. Aqueous samples were introduced with a pneumatic nebulization system. The detection limit for carbon was 0. 047μg/mL.The method was applied to the analysis for tap water and results were satisfactory.

Direct Electron Communication Between Glucose Oxidase and Carbon Electrode Covered with Polypyrrole

CHI Qi-jin, DONG Shao-jun

1996, 12(1):  37-43. 

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Glucose oxidase can be effectively adsorbed onto the polypyrrole (PPy) thin film electrochemically formed on an anodized galssy carbon electrode (GCEa). Direct electron communication between the redox of GODand the modified electrode was successfully achieved, which was detected using cyclic voltammetry. GODentrapped in PPy film still remained its biological activity and could catalyze the oxidation of glucose. As a third generation biosensor, GOD-PPy/GCEa responded linearly up to 20 mMglucose with a wider linear concentration range.

MALDI Mass Spectrometry Analysis of Human Hemoglobin

PENG Wei-xian

1996, 12(1):  44-49. 

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Matrix-assisted laser desorption/ionisation(MALDI) mass spectra in matrices DHBs and ferulic acid have been taken and used to determine the molecular weight of one of the variants of human hemoglobin. Asingle laser operating at 355 nm was used to irradiate the sample droplet spots on a target for both desorption and ionisation. Ions were analyzed and detected by a reflectron time-of-flight mass spectrometer system. The mass values of α-chain and β-chain without heme group for a kind of human hemoglobin molecules were determined, which are 15275 Da and 16060Da respectively, with the accuracy of 0. 03%. The various factors influencing the resolution of mass spectrum were discussed.

Stereoselective Synthesis of cis-1, 2-cyclopropane Derivatives

DING Wei-yu, HAN Zi-heng, CHEN Ya-li, ZOU Yong-jun, LIU Xin

1996, 12(1):  50-55. 

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Carbomethoxymethylenetriphenylar 1, or its arsonium bromide in the presence of K₂CO₃, reacts with 2, 2-dialkyl-1, 3-dioxa-5-substituted-benzal-4, 6-dione 2 to give cis-1-methoxycarbonyl-2-aryl-6, 6-dialky-5, 7-dioxa-spiro-[2, 5]-4,8-octanadione 3 with a moderate to good yield.

Quantum Chemistry Studies on the Difference of Structures and Electronic Properties of Polyacene,Polypyridinopyridine and Paracyanogen

YU Yan-chun, LIU Lian-li, SU Zhong-min, SHI Zhong-liang, XIE De-min

1996, 12(1):  56-59. 

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Polyacene (PAS), polypyridinopyridine (PPyPy) obtained by substitution of -N=for -CH=in PAS, and paracyanogen (Pc) molecules have been studied using quantum chemistry MNDO, 1Dtight-binding CNDO/2-CDmethods. The analyses of the energy band structures indicate that the substitution of Natoms changes the molecular structures and increases the activity points of electrophilic or nucleophilic doping, but intrinsical conductivity is not improved.

Studies on the Relationship Between Electronic Structures and Superconducting Properties of TlBaCaCuO, BiSrCaCuO and XBaCuO(X=Y, Nd, Dy) Systems

LI Ping, XIAO Shen-xiu, CHEN Tian-lang, LI Li

1996, 12(1):  60-69. 

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The electronic structures of TIBaCaCuO, BiSrCaCuO and XBaCuO (X=Y,Nd, DY) systems were calculated using DV-Xa method. According to the calculated results, the relationships between electronic structures and superconducting properties were studied, and some experimental facts were explained.

Studies on Catalysis in Partial Oxidation of Methane to Syngas(Ⅰ)──Performance and Characterization of Ni-based Catalysts

CHEN Ping, ZHANG Hong-bin, LIN Guo-dong, TSAI Khi-rui

1996, 12(1):  70-80. 

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Highly active and selective Ni-based catalysts for partial oxidation of methane (POM) to syngas (CO/H,) have been studied and developed. Spectroscopic characterization by XRD, XPS, EPR, etc. demonstrated that under the POMreaction conditions, the Ni-components of the catalysts investigated were reduced and enriched on the surface to form metallic Ni0-phase. Acomparative study of the first series of transition-metals showed that only Ni and Co have a high POMactivity and selectivity, whereas the others (including Mn, Fe, Cu, etc.) give mainly complete combustion products, Co, and H₂O. The results favor the following viewpoints: the PoMactivity is related with the rapidly changeable valence transitionmetal sites, M0/M²⁺(e. g. Ni0/Ni²⁺), on the surface of the functioning catalysts;the transition-metal sites in zero-valence state seem to be responsible for the activation and dehydrogenation of methane by homolytic splitting of its C-Hbonds on these sites. and the nature of rapidly changeable valence of the active sties is requisite for activation and rapid conversion of dioxygen.

LaSrNiO_4-λwith K₂NiF₄Strcture──A Highly Active Catalyst for Direct Decomposition of Nitrogen Monoxide

ZHAO Zhen, YANG Xiang-guang, WU Yue

1996, 12(1):  81-86. 

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A series of perovskite-like mixed oxides La_2-xSr_xMO_4±λ(M =Cu, Co,Ni; x=0,1) was prepared and characterized using X-ray powder diffraction. The catalytic properties of these catalysts in NOdecompositiori were tested. The results showed that LaSrNiO_4-λwith K₂NiF₄structure is very active and stable for the decomposition of NO.

Studies on the Preparation and Catalytic properties of Fe-C-Mn Ultrafine particle Catalyst in F-T synthesis

ZHANG Jing-chang, LU jiang-yin, CAO Wei-liang, YANG Lin-shong

1996, 12(1):  87-91. 

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Based on the Fe/Cultrafine particle obtained by means of laser pyrolysis method, a series of Fe-C-Mn ultrafine particle catalysts for F-Tsynthesis were prepared by adding certain amounts of Mn organic compounds to the Fe/C UFP. XRD and TEM tests for the obtained catalysts showed that the active phases, α-Fe, Fe₃C and (Fe,Mn)O. were directly obtained. and that the particle size was in the range of 2-4 nm. The catalysts so obtained have stable structure, long life, high activity and selectivity for light olefins, especially for propylene. Testing of the crystal structure in the process of the reaction demonstrated the carbonide mechanism of FTsynthesis and the presence of α-Fe, Fe_xC_yand (Fe, Mn)O, thus supporting the belief that these are the active phases.

Mass Transport of β-Diketonate Precursors for MOCVD of YBa₂Cu₃O_7-δHigh T_cSuperconducting Thin Films

MENG Guang-yao, YUAN Zhi-hao, YANG Ping-hua, PENG Ding-kun

1996, 12(1):  92-101. 

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Mass transport of Y(dpm)₂Ba(dpm)₅·OH·2Ho and Cu(dpm)₂by a carrier gas(argon) was theoretically considered and experimentally studied as a function of the system with operating parameters including temperature, carrier gas flow rate and system pressure. The experimental results are in a good agreement with the theoretical prediction. The mechanism of mass transport of these organometallic precursors and their use for YBCO film stoichiometry control and reproducibility are discussed.

Synthesis of Snake-cage Resins and Study of Their Separation Ability

ZHU Chang-ying, WU Shi-hua, LI Lian-rong, ZUO Ju

1996, 12(1):  102-107. 

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Several kinds of snake-cage resins containing both carboxylic and quaternary ammonium groups were synthesized from cage resin with 7 % crosslinking. The influence of the crosslinking degree on retardation capacity and separation ability has been studied. These resins were used to separate the water-soluble nonvolatile impurities (NVI) from the spinning SQ lvent of polyacrylonitrile-sodium thiocyanate solution. Satisfactory results were achieved.

Synthesis and Crystal Structure Characterization of [Zr(HPO₄)(PO₄)F₂]·1.5H₃NCH₂CH₂NH₃

XU Jia-ning, ZHAO Yu-e, CHEN Jie-sheng, SONG Tian-you, XU Ru-ren

1996, 12(1):  108-110. 

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The synthesis of crystalline zirconiurn phosphates was first reported in 1964 by Clearfield and Stynes, who determined the tormula as Zr(HPO₄) (PO₄)F₂ (a-Zrp) based on chemical compositiondehydration and ion-exchange be-haviour. Since then, many other crystalline.

Selection of Trypsin Inhibitors in Phage Peptide Library Using Model Pepeide Mimicking the Active Site of Trypsin

QI Jie, FANG Rui, LU Zhi-bin, ZHou Hui, LI Wei, SHEN Jia-cong

1996, 12(1):  111-113. 

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Recently, the studies of X-ray and molecular biology on the intereacion of proteins of the protein molecule takes part in the interacion other than the whole molecule, and shore peptides bearing critical binding residues can be used to chemically mimic the folded antigenic determinants on proteins.

A New Type of Silicone Rubber Membrane for Amperometric Oxygen Gas Sensor

LIU Shan-jun, SHEN Han-xi, QIU Ying-hua, FENG Jian-xing

1996, 12(1):  114-119. 

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Clark was the first to couple an electrochemical sensor with gas permeablemembrane e. g. polyethylene membrane for blood analysis. This type of mem-brane-covered sensors has found wide applications. The oxygen permeability of the membrane and geometry of the cathode are generally considered to be the main factors in controlling the characteristics of Clark-type sensors. Sawyer et al.

Oxidative Methylation of Toluene with Methane over K-exchanged Y Type Zeolite Catalyst Promoted with Alkali Metal Bromide and Alkali Metal Oxide

ZHOU Ling-ping, TAO Ke-yi, LI Wei, SU Ming, LI He-xuan, Hideshi Hattori

1996, 12(1):  120-124. 

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Many research groups are cbased chemicals with natural gas and coal-based chemicals. It is known that styrene is one of the most important industrial monomers. Currently，styrene is produced by catalytic alkylation of benzene with ethylene over A1C1₃-HCl cata-lyst.