Table of Content

24 December 2003, Volume 19 Issue 4

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Articles

Synthesis and One-dimensional Structure of Cobalt(Ⅱ) Complex [(NaOC₂H₅)CoL₂]_n

LI Ling, GU Wen, YAN Shi-ping, CHENG Peng, LIAO Dai-zheng, JIANG Zong-hui, SHEN Pan-wen

2003, 19(4):  379-382. 

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The treatment of bis(2-hydroxybenzyl)-amine(HL) with NaOH and Co(Ⅱ)(NO)₂ gives isostructural one-dimensional coordination polymers [(NaOC₂H₅)CoL₂]_n(1). The cobalt ions have an octahedral geometry and are coordinated by two crystallographically independent ligands which are further linked by μ-O_phenol bridged Co and Na atoms to give a one-dimentional structure.

Influence of Annealing on Properties of ZnO Films Grown via Plasma-enhanced MOCVD

ZHAO Bai-jun, DU Guo-tong, YANG Hong-jun, WANG Jinz-hong, ZHANG Yuan-tao, YANG Xiao-tian, LIU Bo-yang, MA Yan, YANG Tian-peng, LIU Da-li, LI Wan-cheng, FANG Xiu-jun

2003, 19(4):  383-385. 

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The structural and the optical properties of ZnO films with high quality grown via plasma-enhanced metal-organic chemical vapour deposition(MOCVD) on C-plane sapphire substrate were studied. The crystallinity and the optical properties of the films are greatly improved having been annealed in oxygen plasma atmosphere. The structure, the band gap and the binding energy of O_1s electrons, and the molar ratio of O to Zn were determined by X-ray diffraction(XRD), photoluminescence(PL) and X-ray photoelectron scan methods. For both the annealed and the as-grown films, the exciton peak features were observed at room temperature. The band-edge photoluminescence of the annealed film is much stronger than that of the as-grown film, and the exciton peak relating to the deep level at 439 nm disappears. The molar ratio of O to Zn in the annealed film is 0.91, while it is 0.78 for the as-grown film.

Studies of Active Ingredients in Cough Syrup by Capillary Zone Electrophoresis with Amperometric Detection

ZHOU Tian-shu, WANG Ai-fang, WU Fang, SHI Guo-yue, FANG Yu-zhi

2003, 19(4):  386-389. 

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The present paper covers a simple, reliable and reproducible method, based on capillary zone electrophoresis(CZE) with amperometric detection(AD), for the separation and the determination of ephedrine hydrochloride, promethazine hydrochloride and codeine phosphate. Under the optimal conditions, the three analytes were base-line separated completely within 16 min. Good linear relationships between the peak heights and the concentrations of the three analytes were obtained with the correlation coefficients better than 0.9993. The method was directly applied to the determination of the active ingredients in pharmaceutical preparations and the assay results were satisfactory.

Application of Polyaniline Incorporated Carbon Particles Coated Platinum Electrode in Coulometric Titration to Determination of Polyisoprene Alcohol

ZHAO Ge, LIU Meng, LIU Kuai-zhi, QU Jiang-ying, CHENG Gang, DU Zu-ling

2003, 19(4):  390-394. 

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The feasibility of using electrodes modified with polyaniline incorporated carbon particles films for improving the precision of coulometric titration is demonstrated. The problem of large deviation produced during determining polyisoprene by coulometric titration with direct titration technique(double Pt electrodes indicating electrode) has been solved. In the titration process, polyisoprene alcohol, an electro-inactive species, is adsorbed on the surface of the bare Pt electrode, which inhibits the electrode reaction of Br^- and Br₂. Therefore, when the titration reaches the end-point, the detected current will slowly change with time, which can make the repeatability of end-point poor. The atomic force microscopic images show the morphology of the electrode surface of adsorbing polyisoprene alcohol. The application of the chemically modified electrode instead of the bare Pt electrode to indicating the end-point has been investigated. The results show that the Pt electrode coated with polyaniline incorporated carbon particles films is an excellent indicator electrode. This electrode has advantages that the indicating signals are sharp and repeatable at end-point. The precision and the accuracy of the determination of polyisoprene alcohol are satisfactory.

Determination of Trace Titanium by Solid Substrate-Room Temperature Phosphorimetry with 4,5-Dibromophenylfluorone as Luminescent Ligand and Triton X-100 as Sensitizer

LIU Jia-ming, YANG Tian-long, YAN Hai-gang, SHEN Li-shuang, LI Long-di

2003, 19(4):  395-398. 

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A new highly sensitive solid substrate room temperature phosphorimetry for the determination of trace titanium is proposed based on the sensitization of Triton X-100 to the SS-RTP intensity of 4,5-dibromophenylfluorone-titanium complex adsorbed on the filter paper substrate modified by gelatin. When Triton X-100 was added into the luminescence system, the RTP intensity was raised 3 times stronger than that of the system without Triton X-100. The linear dynamic range of the new method is 0.64～3.2 fg/spot(0.4 μL) with a detection limit of 12.8 ag/spot, and the regression equation of the working curve is ΔI_p =482.0+119.5m_Ti(Ⅳ)(fg/spot), the correlation coefficient r=0.9992, n=6. The phosphorescence lifetime(τ=0.85 ms) was also determined. The recoveries(and RSD) for the determinations of titanium in human hair and tea samples were 101.0%(3.0%) and 99.97%(4.2%), respectively.

Non-decoloured In-gel Digestion of Coomassie Blue-stained Proteins

ZHANG Guo-an, BAO Hui-min, FAN Hui-zhi, YANG Peng-yuan

2003, 19(4):  399-403. 

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A simplified method is presented for tryptic digestion of Coomassie brilliant blue(CBB)-stained proteins in polyacrylamide gels. Compared with conventional methods, the proposed method does not require a removal of the dye before digestion, and is thus faster and saves a lot of labor. The resulted digest can be analyzed by either RPLC/ESIMS or MALDI MS for identification of the protein in a conventional way. Model studies with bovine serum albumin(BSA) showed that 50 ng of the protein could be routinely identified. The simplified procedure displays a tendency to produce more incompletely cleaved peptides, which is favorable for improving the sequence coverage.

Denatured Thermodynamics of Proteins in Weak Cation-exchange Chromatography

LI Rong, CHEN Guo-Liang

2003, 19(4):  404-408. 

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The thermostability of some proteins in weak cation-exchange chromatography was investigated at 20-80 ℃. The results show that there is a fixed thermal denaturation transition temperature for each protein. The appearance of the thermal transition temperature indicates that the conformations of the proteins are destroyed seriously. The thermal behavior of the proteins in weak cation-exchange and hydrophobic interaction chromatographies were compared in a wide temperature range. It was found that the proteins have a higher thermostability in a weak cation-exchange chromatography system. The thermodynamic parameters(ΔH⁰, ΔS⁰) of those proteins were determined by means of Van't Hoff relationship(lnk'-1/T). According to standard entropy change(ΔS⁰), the conformational change of the proteins was judged in the chromatographic process. The linear relationships between ΔH⁰ and ΔS⁰ can be used to evaluate "compensation temperature"(β) at the protein denaturation and identify the identity of the protein retention mechanism in weak cation-exchange chromatography.

Construction and Application of a PVC Membrane Enoxacin Ion-selective Electrode Based on a Needle-shaped Inner Reference Electrode

HUANG Chao-lun, LI Rui-fen, XIU Rong

2003, 19(4):  409-412. 

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A PVC membrane enoxacin ion-selective electrode based on a needle-shaped inner reference electrode was prepared. A Ag/AgCl wire was used as the substrate of this electrode. It was previously coated with a thin sheet of urea-formaldehyde resin containing Cl^- ions to form a needle-shaped inner reference electrode, then the inner reference electrode was coated with a thin sheet of a PVC membrane containing an enoxacin tetraphenylborate ion-pair complex. The influences of various ion-pair complexes, concentrations of the active components in the membrane and the plasticizers on the performance of the electrode were studied by orthogonal design. The linear response range of the electrode was 7.9×10^-5-1.0×10^-2 mol/L. The detection limit was 2.0×10^-5 mol/L. The slope was 30.4 mV/decade(25 ℃). The electrode can be used for the potentiometric determination of enoxacin tablets directly. The average recovery was 100.4%, and the RSD was 0.9%. The results agreed with those determined by the method in Chinese Pharmacopoeia.

Electrochemical Metalloimmunoassay Based on Enlargement of Gold Nanoparticle Label Treated with Ag Enhancement System

WANG Mei-jia, YUAN Hang, JI Xiao-hui, LIU Zhao-yue, JIA Ruo-kun, WANG Lian-ying, LIU Yan-mei, MA Lan, LI Jing-hong, BAI Yu-bai, LI Tie-jin

2003, 19(4):  413-416. 

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A novel sensitive electrochemical immunoassay with colloidal gold as the antibody labeling tag and subsequent signal amplification by silver enhancement is described. Colloidal gold was treated by a light-sensitive silver enhancement system which made silver deposit on the surface of colloidal gold(form Au/Ag core-shell structure), followed by the release of the metallic silver atoms anchored on the antibody by oxidative dissolution of them in an acidic solution and the indirect determination of the dissolved Agsup>+ ions by anodic stripping voltammetry(ASV) at a carbon fiber microelectrode. The electrochemical signal is directly proportional to the amount of analyte(goat IgG) in the standard or a sample. The method was evaluated by means of a noncompetitive heterogeneous immunoassay of immunoglobulin G(IgG) with a concentration as low as 0.2 ng/mL. The high performance of the method is related to the sensitive ASV determination of silver(Ⅰ) at a carbon fiber microelectrode and to the release of a large number of Ag⁺ ions from each silver shell anchored on the analyte(goat IgG).

Comparison of Pb, Cd Adsorption to Surface Coatings Developed in Natural Waters with that in Plant Effluents

DONG De-ming, LI Yu, HUA Xiu-yi, ZHANG Jing-jing

2003, 19(4):  417-421. 

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The comparative studies of Pb and Cd adsorption to the surface coatings(Fe, Mn, Al oxides, organic materials, and associated minerals), which were developed on glass slides in five natural and two technical waters(plant effluents), were carried out under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0.05 mol/L, 25 ℃ and pH 6.0). The classical Langmuir adsorption isotherm was applied to estimating the equilibrium coefficients of Pb and Cd adsorption to the surface coatings. The results show that the maximum adsorption of Pb and Cd to the surface coatings mentioned above varied widely. There was a systemic increase in the maximum adsorption of Pb and Cd to the surface coatings with increasing the contents of Mn and Fe oxides in the surface coatings in significant correlation, respectively, not only highlighting the relative importance of the metal oxide fraction for Pb and Cd adsorption to the surface coatings developed in natural and technical water samples, but also implying the same adsorption mechanisms of Pb and Cd to the surface coatings developed both in natural and technical water samples.

Two New Compounds from Rhododendron Przewalskii Maxim

LI Guo-qiang, JIA Zhong-jian, ZHANG Shu-sheng

2003, 19(4):  422-424. 

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Two new ionone derivatives, rhododendrone A and rhododendronside, have been isolated from the alcoholic extract of the aerial parts of Rhododendron Przewalskii Maxim. The structures of the two compounds, (3R,6S)-3-hydroxy-α-ionone 1 and 1,1,5-trimethyl-6-(3-hydroxyl)cyclohexene-5-yl-1-β-D-pyranoglucoside 2, have been elucidated on the basis of the spectroscopic analyses.

Facile and Efficient Syntheses of (±)-2,6-Dimethyl-6-hydroxy-2,7-octadienoic Acid and Its Methyl Ester

LIU Hong-xing, CHEN Xi-hui, HUANG Chu-sheng

2003, 19(4):  425-427. 

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The facile and efficient total syntheses of monoterpenoid acid 7a and its ester 7b, isolated from Artemisia siebert and Piper aduncum respectively, can be completed in four steps with an overall yield 41%.

Lipophilic Enhance of Vitamin C Protective Activity Against Free-radical-induced Damage in vivo

LUO Xu-yang, LIU Zai-qun, SUN Yun-xiu, SUI Da-yuan, YU Xiao-feng, QU Shao-chun

2003, 19(4):  428-431. 

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A group of experimental rats under free radical damage are given various amounts of a lipophilic vitamin C(ascorbyl-6-laurate, VC-12), and its parent compound, vitamin C, respectively. It has been found that the effects of 1.12 mmol/kg VC-12 on decreasing triglyceride(TG), total cholesterol(TC), low density lipoprotein cholesterol(LDL-c) and lipid peroxide(LPO), and increasing high density lipoprotein cholesterol(HDL-c) and superoxide dismutase(SOD) are similar to those of 2.27 mmol/kg vitamin C. In addition, VC-12(1.12 mmol/kg) can increase the prostacycline(PGI₂) and decrease the thromboxane(TXA₂) even better than vitamin C(2.27 mmol/kg). The above facts demonstrate that the antioxidative activity of VC-12 is higher than twice that of vitamin C. So, ascorbyl-6-laurate may be a novel antioxidant drug against free radical damage.

Syntheses of β-Hydroxy Ketones by Organosamarium

YU Ming-xin, ZHANG Yong-min

2003, 19(4):  432-433. 

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An organosamarium reagent was prepared via the reaction of α-bromoacetophenone with samarium. This organosamarium reagent reacted with aldehydes to give β-hydroxy ketones. A possible reaction process was suggested.

Synthesis and Crystal Structure of Lanthanum Nitrate with Methyl-2-pyridyl Ketone Benzoyl Hydrazone

TAI Xi-shi, YIN Xian-hong, LIU Debo, TAN Min-yu, YU Kai-bei

2003, 19(4):  434-436. 

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A novel La complex with methyl-2-pyridyl ketone benzoyl hydrazone has been synthesized and determined by single crystal X-ray diffraction. The crystal is monoclinic with space group C2/c, a=1.7081(3) nm, b=1.5660(3) nm, c=1.3512(3) nm, α=90.00°, β=94.39(1)°, γ=90.00°, V=3.6037(12) nm³, Z=4. The complex is a ten-coordinated one with a lanthanum ion surrounded by a N₄O₆ set. The crystal structure is stabilized by hydrogen bonds between water molecules and NO₃^- anions.

Studies on Synthesis and Biological Activities of Novel Triazole Compounds Containing Pyrimidine or N,N-Dialkyldithiocarbamate Ring

XU Liang-zhong, ZHANG Shu-sheng, GAO Hong-rong, JIAO Kui

2003, 19(4):  437-441. 

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Twelve of the title compounds were synthesized. Their structures were identified by means of IR, EA, ¹H NMR and MS. The IR spectra clearly show that the absorptions in the regions of 1716-1666 cm^-1 and 1505-1499 cm^-1 are the characteristic absorption bands for ν_C=O and ν_C=N. In the ¹H NMR spectra of target compounds(10a-10g), three protons of a -CH-CH₂- group present three sets of quartet peaks of the protons. The preliminary bioassays showed that the synthesized compounds exhibited some activities of fungicides and plant growth regulators.

Purification and Properties of Superoxide Dismutase(SOD) in Allium Sativum

TENG Li-rong, WANG Ya-jun, WU Min, HONG Shui-sheng, CHEN Jia, Meng Qing-fan, LIU Lan-ying

2003, 19(4):  442-445. 

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Superoxide dismutases(SODs) were purified to homogeneity from Allium Sativum by means of ammonium sulfate precipitation and column chromatography with DEAE-cellulose(DE52) and Sephadex G-75. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-AGE), Allium Sativum is predicted to contain four SODs. The molecular weights of the native SODs are 41.3 kD, 37.0 kD, 35.2 kD and 31.0 kD, which consist of subunits of 20.7 kD, 18.4 kD, 17.7 kD and 15.4 kD respectively. Because of their specific sensitivity to hydrogen peroxide, cyanogens potassium and chloroform-alcohol, the SODs in Allium Sativum appear to be Cu, Zn-SOD isoenzymes. The isoelectric analysis indicates that three of the four isoenzymes are acidic proteins with isoelectric points at pH 3.5, 3.7 and 4.0, respectively, and the fourth one is a basic protein with isoeletric point at pH 8.5.

Improvement of Properties of Pseudomonas sp. Lipase in Resolution of 2-Octanol

WANG Zhi, QUAN Jing, WENG Liang, ZHENG Liang-yu, LIU Ning, DONG Huan, CAO Shu-gui

2003, 19(4):  446-449. 

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A novel preparation method was developed to form a surfactant-lipase complex for the resolution of 2-octanol in a solvent-free system. The E value was improved from 6.64 to 120.2. The lipase modified by the anionic surfactant possessed a low solubility in the solvent-free system, which was beneficial to the recovery and the repeated usage of the lipase. The surfactant-lipase complex maintained a high enantioselectivity after five cycles of usage. The effect of water on both the activity and the enantioselectivity of the lipase has also been investigated; the direct addition of a salt hydrate pair of Na₄P₂O₇·H₂O and Na₄P₂O₇ can dramatically activate the modified enzyme.

Structure and Luminescence Characteristics of Europium Activated Strontium Silicates Sr(Eu,Bi)SiO₃ and Sr(Eu,Bi)₂SiO₄

YANG Jing-hai, GONG Jie, FAN Hou-gang, ZHANG Yong-jun, YANG Li-li, CHEN Gang

2003, 19(4):  450-453. 

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Sr₂SiO₄∶Eu³⁺,Bi³⁺ and SrSiO₃∶Eu³⁺,Bi³⁺ samples were synthesized at high temperature and high pressure. The effect of high pressure on the structure and luminescence properties of the samples were studied. As a comparison, the samples were also prepared by the method of sol-gel at high temperature and atmospheric pressure. The SrSiO₃∶Eu³⁺,Bi³⁺ prepared at atmosphere has a hexagonal phase structure; in the pressure range of 2.34-4.10 GPa, it is transformed into a pseudo-orthorhombic structure(monoclinic), and in the pressure range of 4.10-4.15 GPa, the structure change of Sr₂SiO₄∶Eu³⁺, Bi³⁺ has not been observed, it maintains the monoclinic structure of the samples synthesized at an atmospheric pressure. High pressure makes the luminescence properties of the samples changed obviously. The intensity and the relative quantum luminescent efficiency decrease, the half-width increases obviously and the red shift occurs. The changes of the luminescence properties result from the pressure-induced changes of the crystal structures.

Size Dependence of Electronic Excitation Energy in Linear C_2nH and C_2n-1N

ZHANG Cong-jie, CAO Ze-xing, ZHANG Qian-er

2003, 19(4):  454-458. 

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The geometries, bondings, and vibrational frequencies of C_2nH (n=3-9) and C_2n-1N(n=3-9) were investigated by means of density functional theory(DFT). The vertical excitation energies for the X²Π→²Π transitions of C_2nH(n=3-9) and for the X²Σ→²Π and the X²Π→²Π transitions of C_2n-1N(n=3-9) have been calculated by the time-dependent density functional theory(TD-DFT) approach. On the basis of present calculations, the explicit expression for the wavelengths of the excitation energies in linear carbon chains is suggested, namely, λ₀=[1240.6A/(2+√3n+6-√3n+3)](1-Be^-Cn), where A=3.24463, B=0.90742, and C=0.07862 for C_2nH, and A=2.94714, B=0.83929, and C=0.08539 for C_2n-1N. In consideration of a comparison of the theory with the experiment, both the expressions are modified as λ₁=0.92(λ₀+100) and λ₁=0.95(λ₀+90) for C_2nH and C_2n-1N, respectively.

Preparation and Standard Formation Enthalpy of 2-Amino-4,6-dimethylpyrimidine and Its Related Complexes of Copper

CHEN San-ping, WEI Qing, JIAO Bao-juan, GAO Sheng-li

2003, 19(4):  459-463. 

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The complexes of hydrous copper chloride and copper nitrate with 2-amino-4,6-dimethylpyrimidine(ADMP) were prepared via reflux in alcohol. The compositions of the complexes were identified as Cu(ADMP)₂CL₂·2H₂O(b) and Cu(ADMP)(NO₃)₂·H₂O(c) by chemical and elemental analyses. The complexes were characterized by IR, XPS, ¹H NMR and TG-DTG techniques. The constant-volume combustion energies of ADMP and the complexes, Δ_cE, were determined by a precise rotating-bomb calorimeter at 298.15 K. They were (-3664.53±1.18), (-4978.47±2.72) and (-1696.70±1.36) Kj/mol, respectively. Their standard enthalpies of combustion, Δ_cH⁰_m, and standard enthalpies of formation, Δ_fH⁰_m, were calculated to be (-3666.39±1.18), (-4977.23±2.72), (-1691.12±1.36) Kj/mol and (19.09±1.43), (-2041.80±3.29), (-2397.24±1.65) Kj/mol, respectively.

Studies on Kinetics of Crystallization of PA6/UFAPR Composites

DING Xue-jia, XU Ri-wei, ZHANG Bing-wei, YU Ding-sheng, CHEN Hong

2003, 19(4):  464-469. 

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The influence of Ultrafine Full-Vulcanized Acrylate Powdered Rubber(UFAPR) on the isothermal crystallization kinetics and nonisothermal crystallization behavior of PA6 has been studied by means of DSC. The results show that with the introduction of a small amount of UFAPR, the crystallization rate of PA6 can be increased obviously, and the crystallization temperature range can be augmented and the crystallite size distribution of the crystal can be narrowed down. The change of free energy perpendicular to the crystal nucleus, which has been calculated according to the Hoffman theory, is consistent with the result of Avrami′s equation. The unit surface free energy of the radial-developing crystal spherulite decreases while the crystallization rate of PA6 increases with the introduction of UFAPR. Meanwhile, it is shown by means of the polarizing microscope(PLM) that the crystal size drops down and the number of the crystal grains augments with the addition of UFAPR, which shows that UFAPR can function as a nucleating agent.

Syntheses of Novel Asymmetric Cyclopentanone Dyes and Measurement of Two-photon Absorption Cross-section

WANG Tao, WU Fei-peng, SHI Meng-quan, GUO Heng-chang, WU Cheng-yin, JIANG Hong-bing, GONG Qi-huang

2003, 19(4):  470-473. 

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A simple synthesis route with a high yield of novel asymmetric cyclopentanone dyes 3a-3e and their highly two-photon up-converted fluorescences are reported. The dyes have good solubilities in most of ordinary solvents, a wide UV absorption wavelength range from 380-540 nm, and high fluorescence quantum yields. The two-photon absorption cross-sections of dyes 3a-3e were measured in chloroform by a two-photon induced fluorescence method. All of these properties of the new dyes make them suitable for being used as two-photon fluorescent probes.

Influence of Surface Structure of Platinum Electrodes on Electrooxidation of CO

XIA Xing-hua, ZHANG Dai, SONG Yan-yan

2003, 19(4):  474-480. 

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The oxidation of CO on platinum electrodes in an acid solution was studied with the conventional electrochemical methods and the on-line electrochemical mass spectroscopy. It was found that this reaction is strongly determined by the surface morphology of platinum. The pretreatment of platinum electrodes can change the surface properties dramatically, in consequence it can improve the electrocatalytic activity towards the electrooxidation of CO. The existence of surface active sites on the roughened platinum electrodes can be used to explain its high electrocatalysis towards the oxidation of CO.

Theoretical Studies on Formation Mechanism of Resonance States for Na+I₂→Na⁺+I₂ System

SUN Xiao-min, MA Wan-yong, CAI Zheng-ting, FENG Da-cheng

2003, 19(4):  481-483. 

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An extended linear combination of arrangement channels-scattering wave-function(LCAC-SW) quantum scattering dynamic method combined with ab initio quantum chemical calculation was used to study the formation mechanism of the resonance states for the collinear Na+I₂→Na⁺+I₂ ion-pair formation process on Aten-Lanting-Los potential energy surface. The resonance energy and the resonance width or the lifetime for the first resonance peak were calculated. The resonance can be identified as the Feshbach type and the physical interpretation is given. The geometric structure of the resonance state for the title system has been optimized.

Fluorescence Quenching of Anthracene by N,N-Diethylaniline and Phenothiazine in Triton X-100/n-C₁₀H₂₁OH/H₂O Microemulsion

GUO Xia, XU Hui, GUO Rong

2003, 19(4):  484-488. 

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The photo-induced electron transfer reactions of anthracene with N,N-diethylaniline(DEA) and phenothiazine(PTZ) occur in the membrane phase of a Triton X-100/n-C₁₀H₂₁OH(1-decanol)/H₂O microemulsion. DEA and PTZ exist in the membrane phase of the microemulsion. Anthracene exists in the oil continuous phase of the W/O microemulsion and in the oil core and membrane phase of the O/W microemulsion.

Studies on Effect of Conformation on Spin Multiplicity of m-Phenylene Type of Biradicals by Different Approaches

WANG Li-min, ZHANG Jing-ping, WANG Rong-shun

2003, 19(4):  489-493. 

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The effect of the conformation on the spin multiplicity of the ground state and the stability of the ground state were investigated for m-phenylene type of biradicals by means of comparative study with DFT, CASSCF and AM1-CI approaches. It was found that AM1-CI approach is reliable in dealing with the stability of the high-spin ground state with the change of conformation; DFT method can give the reasonable results of the spin density of the high-spin state. Furthermore, when one or two radical centers are twisted sufficiently out of the conjugation with the benzene ring, m-phenylene turns into weak ferromagnetic and weak antiferromagnetic coupling units, respectively.

Effect of Some Metal Ion Dopants on Electrochemical Properties of Ni(OH)₂ Film Electrode

ZHANG Heng-bin, LIU Han-san, CAO Xue-jing, SUN Chia-chung

2003, 19(4):  494-498. 

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The Ni(OH)₂ film electrodes doped respectively with alkali-earth metal aluminum, lead, partial transition metal and some rare-earth metal(altogether 17 kinds of metals) ions were prepared by cathode electrodeposition. The electrode reaction reversibility, the difficult extent of oxygen evolution, the proton diffusion coefficient, the discharge potential of middle value and the active material utilization of the Ni(OH)₂ film electrode were compared with those of the ones doped with the metal ions by means of cyclic voltammetry, potential step and constant current charge-discharge experiments. It was found that Ca²⁺, Co²⁺, Cd²⁺, Al³⁺ etc. have obviously positive effect.

Studies on Preparation of Co-Bi Alloy Films by Electrodeposition From Nonaqueous Medium

LI Gao-ren, TONG Ye-xiang, LIU Guan-kun

2003, 19(4):  499-503. 

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Cyclic voltammetry and potentiostatic electrolysis were used to investigate the preparation of Co-Bi alloy films in a LiClO₄-DMSO system. The experimental results indicate that the Co-Bi alloy films containing 14.35%-29.77% Co can be prepared via potentionstatic electrolysis on Cu substrates, at deposition potential -1.10—-1.65 V(vs. SCE) and by controlling the system composition and deposition condition. They are uniform gray films with a metallic luster and they are adhered firmly to the Cu substrate. The films were analyzed by EDS, SEM and XRD. After heat treatment of crystallization at 275 ℃ for 1 h, the alloy phase of Co-Bi can be confirmed via the XRD pattern.

Luminescence of Nanosized Supramolecular Material of Mesoporous Molecular Sieve and Samarium (Ⅲ) Complex

YIN Wei, ZHANG Mai-sheng

2003, 19(4):  504-507. 

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The solutions of rare earth complexes Sm(Phen)₂(TTA)(Bipy)(NO₃)₃ and Sm(L)_x(TTA)_4-x(NO₃)₃[L=Phen(1,10-phenanthroline) or Bipy(2,2′-bipyridine), x=4, 3, 2, 1, 0; TTA is 2-thenoyltrifluoacetone] in EtOH(1×10^-3 mol/L) were prepared. The coefficients of antenna effect are 31.5, 18.2 and 5.6 for Phen, Bipy and TTA, respectively, when the electron configuration of the excited state of the samarium atom in the complexes is ⁴D_1/2. The fluorescent intensity and the lifetime of the supramolecular encapsulation products of (CH₃)₃Si-MCM-41 and Sm³⁺ complexes are stronger and longer than those of the encapsulation products of MCM-41 and Sm³⁺ complexes respectively. The results show that the host with lipophilic channels is more favourable to the fluorescence of the rare earth complexes than the hydrophilic mesoporous molecular sieve. The fluorescent intensity of (CH₃)₃Si-MCM-41-Sm(Phen)₃(TTA)(NO₃)₃ is the strongest amongthe encapsulation series of Sm³⁺ complexes, which is assumed to result from the greatly reduction of SiO-H vibration relaxation in host (CH₃)₃Si-MCM-41 and the presence of the discrete strong luminescent centres of the guest molecules associated with the nanosized material′s structure. The luminescent decay halftime of the supramolecular materials is much shorter than that of the powder of the samarium complexes. The result shows that the ligand transferring energy from the triplet state to the singlet state of Sm³⁺(T₁→S, intersystem crossing) becomes higher. The fluorescent experimental results indicate that the interaction between the host and the guest influences the luminescent properties of the nanostructured supramolecular materials.

Theoretical Design of High-spin Organic Molecules with Heterocycles as Ferromagnetic Coupling Units

WANG Li-min, ZHANG Jing-ping, WANG Rong-shun

2003, 19(4):  508-511. 

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Novel stable high spin molecules possessing three different arranged fashions are designed with -^·N-N< as a spin-containing(SC) fragment, phenylene as an end group and various aromatic molecules, such as benzene(1), 2,6-pyridine(2), 3,5-pyridine(3), pyridazine(4), 4,6-pyrimidine(5), 2,6-pyrimidine(6), pyrazine(7) and triazine(8), as a ferromagnetic coupling(FC) unit. The effects of the different coupling units on the spin multiplicities of the ground states and their stabilities were investigated by means of AM1-CI approach. It has been found that the spin densities on the two atoms of the SC fragment are different from delocalization results in the specific stability of -^·N-N<. In these molecules, the stabilities of the triplet states decrease when the distance between the atoms of central SC(-N-) increases. It is shown that the heterocycles as the coupling units have influence on the stabilities of the high-spin ground states. That the heteroatom lying in m-phenyl can improve ferromagnetic coupling, while the heteroatom lying in o-phenyl or p-phenyl is not in favor of the ferromagnetic coupling.

Synthesis and Characterization of a Novel Liquid Crystalline Chitin ——Quaternary Ammonium Chitosan Salt

RUAN Yong-hong, DONG Yan-ming, WU Ming-shui, ZENG Man-qing, WANG Shui-ju

2003, 19(4):  512-515. 

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N-Butyl chitosan(NBCS) derivatives were prepared by introducing butyl groups into the amine groups of chitosan via Schiff base intermediates. The quaternization of NBCS was carried out by using ethyl iodide to produce water-soluble cationic polyelectrolytes. The degree of the substitution of the products was measured by means of the electron spectroscopy for a successful chemical analysis. The quaternary ammonium chitosan salt(QACS) was proved to be a novel cholesteric liquid crystalline chitin, by means of the polarized optical microscopy and the circular dichroism spectropolarimetry. The critical mass fraction of the QACS/formic acid solution forming a lyotropic liquid crystal phase was 50%, which was almost the same as that of the NBCS/formic acid solution, but much higher than that of the chitosan in the same solvent.

Novel Single-component Rare Earth Phenolate Catalyst for Ring-opening Polymerization of ε-Caprolactone

FAN Ling, ZHANG Li-fang, SHEN Zhi-quan

2003, 19(4):  516-517. 

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A new Complex from TMPDB and SSDMA: Preparation,Characterization and Photopolymerization

LU Cong-hua, ZHENG Xiao-liang, LUO Chuan-qiou, CAO Wei-xiao

2003, 19(4):  518-520. 

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