Table of Content

24 January 2005, Volume 21 Issue 1

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Articles

Synthesis, Characterization and Conductivity of α-Keggin-type Nanoparticles, Co(en)₃PMo₁₂O₄₀·8H₂O with Optical Activity

HUANG Ru-dan, LI Juan, ZHANG Jing

2005, 21(1):  1-3. 

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Polyoxometallates Co(en)₃PMo₁₂O₄₀·8H₂O(+,-)[abbreviated as PMo₁₂-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time.They were characterized by means of elemental analyses, IR spectrometry and X-ray diffraction.The images of scanning electron microscopy(SEM) and the results of calculation by using the Scherrer equation for the line widths of the XRD patterns were used to estimate the average particle size of the powder products, which was 40 nm.The results show that the nanoparticle size was affected by starting materials′ concentrations.The particles had a small size and a narrow distribution, when the concentrations of H₃PMo₁₂O₄₀·24H₂O and Co(en)₃I₃·H₂O were around 1.7×10^-4 and 1.0×10^-3 mol/L, respectively.When the concentration was increased, there was no significant increase in the particle size, but more polydisperse Co(en)₃(PMo₁₂O₄₀)(+, -) were obtained.In poly(ethylene glycol)(PEG) with an average molecular weight(M_W) of 600 g/mol and containing LiClO₄[n(O)/n(Li)=100∶1] as the supporting electrolyte, the conductivity of the composite system increases upon the addition of PMo₁₂-Co(+ or -) nanoparticles, which was measured by the a.c.impedance technique.The interactions among PEG, LiClO₄, PMo₁₂, and Co can be used to explain that the PMo₁₂-Co(+ or -) nanoparticles could promote the conductivity of the PEG-LiClO₄-PMo₁₂-Co system.

Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl_1-xFe_xO₃ Catalysts

PENG Feng, WANG Hong-juan

2005, 21(1):  4-7. 

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A series of LaAl_1-xFe_xO₃ catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity.The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts.From the TEM pictures of carbon nanotubes, it can be found that the LaAl_1-xFe_xO₃ catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.

Studies of the Intramolecular Aromatic-ring Stacking Interactions in the Ternary Platinum(Ⅱ) Complexes

SUN Hong-liang

2005, 21(1):  8-11. 

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The stability constants of some ternary mixed-ligand complexes, Pt(Phen)(CA)⁺, where Phen=1,10-phenanthroline and CA- =carboxylate, were determined by means of potentiometric pH titration in aqueous solutions(I=0.1 mol/L, KNO₃;25 ℃), and the stability of them was compared with that of the corresponding binary complexes.It was revealed that the ternary complexes containing phenylalkane carboxylates ligands(PCA^-) are much more stable than those formed with formate and acetate.The results indicate that there exist the intramolecular aromatic-ring interactions between the phenanthroline ring of Phen and the phenyl moiety of ligand PCA^- in the ternary mixed-ligand Pt(Phen)(PCA)^- complexes.The extent of the stacking interactions, which depends on the number of methylene groups between the phenyl moieties and the coordinated phenylalkane carboxylate groups, was calculated.The best-fitted stack was obtained for the complexes with 2-phenylacetate and 3-phenylpropionate as the ligands.

Trihydrated Complex of Tetrabenzimidazole Copper(Ⅱ) Sulfate

JIAN Fang-fang, WANG Huan-xiang, XIAO Hai-lian, JIAO Kui

2005, 21(1):  12-16. 

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A Trihydrated complex of benzimidazole copper(Ⅱ) sulfate [(C₇H₆N₂)₄CuSO₄]·3H₂O was synthesized and structurally characterized.The crystal structure of this compound is built up of six solvated water molecules and two dissimilar copper ions identified as Cu1 and Cu2.The coordination geometry of copper(Ⅱ) is a slightly distorted square pyramid.The four equivalent tertiary nitrogen atoms of the benzimidazole ligand form an equatorial plane, while the oxygen atoms of sulfato occupy the axial site.In the solid state, the title compound forms a three dimensional network structure via hydrogen bonds.The benzimidazole, sulfato ion and H₂O moieties are connected by the intermolecular hydrogen bonds.The (EPR) spectrum shows axial symmetry with g_⊥=2.039 and g_||=2.285.Variable temperature magnetic susceptibility shows that there is a weak antiferromagnetic interaction between the neighboring copper(Ⅱ) ions.

Synthesis and Gas-sensing Performance of Nanosized SnO₂

WANG Shu-rong, WU Shi-hua, SHI Juan, ZHENG Xiu-cheng

2005, 21(1):  17-20. 

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Nanosized tin dioxide particles were prepared by sol-gel dialytic processes with tin(Ⅳ) chloride and alcohol as start materials.The nanoparticles of tin dioxide were charactered by thermogravimetry and differential thermal analysis(TG-DTA), X-ray diffraction(XRD), transmission electron microscopy (TEM) and BET.The results show that the average diameter of tin dioxide particles dried at 353 K was about 2 nm.Even if the tin dioxide particles were calcined at 873 K, the average diameter of particles was less than 10 nm.The removal of Cl^- was solved by using this kind of method.The mechanism of the formation of tin dioxide nanosized particles was proposed and analyzed in this paper.We also measured the sensitivity of the sensor based on the tin oxide powder calcined at 673 K to NH₃, alcohol, acetone, hexane and CO.The gas-sensing performance results indicate that this sensor has a higher sensitivity to alcohol and acetone, and selectivity for NH₃, hexane and CO at an operating temperature of 343 K.

Hydrothermal Synthesis and Crystal Structure of Binuclear Copper(Ⅱ) Complex Bridged by 1,2,4,5-Benzenetetracarboxylato Trivalent Anion

YUAN Ji-xin, HU Mao-lin, LI Ju-xia, SONG Xin-yuan

2005, 21(1):  21-23. 

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The title complex [(phen)2Cu(Htcb)Cu(phen)2]H₃tcb(tcb=1,2,4,5-benzenetetracarboxylato tetravalent anion; phen=1,10-phenanthroline) was synthesized by the hydrothermal synthesis method.The crystal structure was determined by single-crystal X-ray diffraction analysis.It crystallizes in the triclinic system with space group P1, a=1.04174(8) nm, b=1.07119(8) nm, c=1.26360(10) nm, α=98.169(2)°, β=99.679(10)°, γ=93.658(10)°, V=1.37031(18) nm³, Z=1.The two copper(Ⅱ) cations are bridged by Htcb in the monodentate fashion, and have the same five-coordinated environment completed by the four N atoms from the two phen molecules and one O atom from the carboxylic group of Htcb respectively, which can be best described as distorted trigonal-bipyramid geometry.Moreover, the three dimensional network is formed by H-bonding interactions [O…O distance from 0.2506(10) nm to 0.3176(11) nm] and π-π stacking interactions between the phen rings of adjacent binuclear entities with a face-to-face separation of ca.0.354 nm.

Electrochemical Study on the Interaction Betwwen Neutral Red and DNA

NIU Shu-yan, ZHANG Shu-sheng, SHI Xin, JIAO Kui

2005, 21(1):  24-27. 

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A voltammetric study of the interaction of neutral Red(NR) with DNA at a gold electrode in a phosphate buffer solution is described.After adding DNA in an NR solution, the reduction peak current of NR decreases.The binding mechahisms of NR to DNA in different pH ranges are different.The reduction peak potential of NR in a pH 7.0 phosphate buffer solution in the presence of DNA shifts positively, indicating that the binding of NR to DNA is intercalation action, but at pH=6.0 the reduction peak potential of NR shifts negatively, indicating that the binding of NR to DNA is electrostatic action.The formed complexes are DNA-NR when [NR]/[DNA]<0.18 and DNA-3NR when [NR]/[DNA]>0.35, respectively.

Cyclam Modified Carbon Paste Electrode as a Potentiometric Sensor For Determination of Cobalt(Ⅱ) Ions

Hamid Reza POURETEDAL, Mohammad Hossein KESHAVARZ

2005, 21(1):  28-31. 

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A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions.The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range 5.0×10^-6_1.0×10^-1 mol/L of CO²⁺ ions with detection limit 2.5×10^-6 mol/L.The sensor exhibits good selectivities for CO²⁺ over a wide variety of other cations.It can be used as an indicator electrode in potentiometric titration of cobalt(Ⅱ) ions as well as in direct determination of cobalt(Ⅱ) ions in wastewater of acidic cobalt electroplating bath.The electrode shows Nernestian behavior in a solution of 25% ethanol.

Polarographic Studies on Associations of Midecamycin and Chloroquine with Hydrogen Peroxide

LI Ning, SONG Jun-feng, XU Mao-tian, ZHANG Ya

2005, 21(1):  32-35. 

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The associations of each of midecamycin and chloroquine phosphate to hydrogen peroxide were studied by using linear-potential scan polarography.In a 0.15 mol/L KH₂PO₄-NaOH(pH 7.4) buffer, the association ratio of the association complex of midecamycin to hydrogen peroxide is 1∶1, and the apparent association constant is 7.18.While in a 0.04 mol/L NH₃·H₂O-NH₄Cl(pH 9.5) buffer, the association ratio and the apparent association constant of the association complex of chloroquine phosphate to hydrogen peroxide are 1∶1 and 45.4, respectively.The formation of the association complexes stabilizes H₂O₂ and results in the accumulation of H₂O₂, which is baneful to human body.

Determination of Active Components in a Natural Herb with Near Infrared Spectroscopy Based on Artificial Neural Networks

LIU Xue-song, QU Hai-bin, CHENG Yi-yu

2005, 21(1):  36-43. 

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The non-linear relationships between the contents of ginsenoside Rg₁, Rb₁, Rd and Panax notoginseng saponins(PNS) in Panax notoginseng root herb and the near infrared(NIR) diffuse reflectance spectra of the herb were established by means of artificial neural networks(ANNs).Four three-layered perception feed-forward networks were trained with an error back-propagation algorithm.The significant principal components of the NIR spectral data matrix were utilized as the input of the networks.The networks architecture and parameters were selected so as to offer less prediction errors.Relative prediction errors for Rg₁, Rb₁, Rd and PNS obtained with the optimum ANN models were 8.99%, 6.54%, 8.29%, and 5.17%, respectively, which were superior to those obtained with PLSR methods.It is verified that ANN is a suitable approach to model this complex non-linearity.The developed method is fast, non-destructive and accurate and it provides a new efficient approach for determining the active components in the complex system of natural herbs.

Luminescent Bacterial Sensors Made from Immobilized Films of Photobacterium Phosphoreum

YIN Ji-qiu, LI Xiao-zhou, ZHOU Chi, ZHANG Yi-hua

2005, 21(1):  44-47. 

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A kind of luminous bacterial sensors that can quickly detect the acute toxicity of environmental pollutants were developed.The method is based on the detection of the cellular light of bright luminous bacillus by means of fixing cells so as to detect acute toxicity of luminous bacillus.The bacterial sensor is composed of immobilized film of photobacterium phosphoreum.These bacterial films are sensitive to detecting the toxicoids, which are difficult or even impossible to be measured by traditional analytical chemistry methods.The films should be stored at 4 ℃ and the stability of the sensors exceeds 1 month with no measurable deterioration of the signal.These results demonstrate that the immobilized film of P.phosphreum can be used to develop the on-line environmental contamination monitor.

Content

Properties of TiO₂-SiO₂ Mixed Oxides and Photocatalytic Oxidation of Heptane and Sulfur Dioxide

XIE Chao, XU Zi-li, YANG Qiu-jing, LI Na, WANG De-bao, DU Yao-guo

2005, 21(1):  48-52. 

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A series of TiO₂-XSiO₂[X denotes the molar fraction(%) of silica in the mixed oxides] with different n(Ti)/n(Si) ratios was prepared with ammonia water as a hydrolysis catalyst.The photocatalysts prepared were characterized by XRD, thermal analysis, FTIR, UV-Vis and SPS.The characterization results of FTIR and UV-Vis spectra show that Ti atoms were gradually changed from octahedral coordination to tetrahedral coordination with the addition of silica, which is not beneficial for obtaining strong Brnsted acidity and higher photocatalytic activity.The photocatalytic activity experiments, which were conducted by using heptane(or SO₂) as the model reactant, showed that TiO₂-SiO₂ containing a suitable amount of silica can exhibit much higher photocatalytic activity than pure TiO₂.The enhanced photocatalytic activity can be attributed to three following factors: (1) smaller crystalline size; (2) higher thermal stability;(3) the new strong Brnsted acidity.

Articles

Removal of Cd(Ⅱ) from Aqueous Solutions by Natural Freshwater Surface Coatings

LI Yu, DONG De-ming, CHEN Li-yuan, HUA Xiu-yi

2005, 21(1):  53-58. 

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Natural freshwater surface coatings(biofilms and associated minerals), which were developed in the Nanhu Lake, Changchun, P.R.China, were used as an efficient biosorbent for the removal of Cd(Ⅱ) from aqueous solutions.The batch experiments were carried out to determine the adsorption properties of Cd(Ⅱ) onto the natural surface coatings.The classical Langmuir adsorption isotherm was applied to estimating the equilibrium coefficients of Cd(Ⅱ) adsorbed on the surface coatings.The results show that the maximum adsorption capacity of the surface coatings is 434.78 μmol Cd/m²(being equal to 0.17 mmol Cd/g of surface coatings or 10.38 mmol Cd/g Fe) and the Cd(Ⅱ) removal from solution media by the natural surface coatings was shown to be strongly affected by solution pH and ion strength.The resulted information also indicates that the maximum Cd removal efficiency(CRE) was determined to be approximately 90% at initial Cd mass concentration of 0.1 mg/L(the concentration limit of Cd (Ⅱ) in wastewaters for discharge in aquatic media in Chinese legislation), and the kinetic adsorption of Cd(Ⅱ) onto the surface coatings is fast with around 70% of the total adsorption-taking place in 150 min in solution under the controlled laboratory conditions (mineral salts solution with defined speciation, ionic strength 0.05 mol/L, and 25 ℃).With the advantage of high Cd adsorption capacity, the natural surface coatings appear to be a potentially effective biosorbent for the removal and recovery of Cd (Ⅱ) from polluted water.

Reactions of Imidates with Phenoxyacetyl Chloride

JIAO Lei, LIANG Yong, WU Chun-zan, HUANG Xu, XU Jia-xi

2005, 21(1):  59-64. 

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The reactions of imidates including cyclic imidates, oxazolines and dihydrooxazine with phenoxyacetyl chloride, were investigated.The results indicate that diacylamide or acylamide was generated from N-phenoxyacetylated imidates, while cyclic imidate oxazolines underwent a ring-opening reaction to yield different amides depending on the reaction conditions.Even under non-nucleophilic conditions, no β-lactam-fused oxazoline derivative was obtained.

Synthesis of Bisphenols Carrying Long Hydrocarbon Side Chains

XU Jing-zhe, JIANG Nan-zhe, ZHANG Jian, JIANG Ri-shan

2005, 21(1):  65-68. 

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Bisphenols containing long aliphatic hydrocarbon side chains were synthesized by the condensation of phenol with aldehyde or ketone in the presence of heteropolyacid.Their structures were characterized by IR, ¹H NMR, ¹³CNMR and element analysis.The experiment results show that when heteropolyacid was used as a catalyst, these bisphenols were obtained in high selectivity and high yields.

Preparation and Crystal Structure of 3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4 ]thiadiazine

ZOU Kai-huang, ZHANG Li-xue, ZHANG An-jiang, LEI Xin-xiang, HUANG Hui-hua, ZHANG Zi-yi

2005, 21(1):  69-72. 

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3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4] thiadiazine, C₁₆H₁₁N₅O₃S, was prepared by the cyclization of 3-(2-hydroxyphenyl)-4-amino-5-mercapto-1,2,4-triazole with 2-bromo-4-nitroacetophenone.The compound was characterized by means of elemental analysis, IR, ¹H NMR, ¹³C NMR, mass spectrometry, and X-ray diffraction.The compound crystallizes in a monoclinic system with space group C_c, a=2.1853(4) nm, b=2.1192(5) nm, c=1.3526(3) nm, β=95.21(2)°, V=6.238(2) nm³ , D_calcd.=1.505 Mg/m³, Z=16, F(000)=2916, R₁=0.0501, wR₂=0.0427.A comparison between the crystal structures of 1,2,4-triazolo[3,4-b] [1,3,4] thiadiazine and 1,2,4-triazolo[3,4-b][1,3,4] thiadiazole was made in the structural view.A two-dimensional network is formed by hydrogen bonds and π-π stacking interactions.

A Simulated Annealing Algorithm for Training Empirical Potential Functions of Protein Folding

WANG Yu-hong, LI Wei

2005, 21(1):  73-77. 

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In this paper are reported the local minimum problem by means of current greedy algorithm for training the empirical potential function of protein folding on 8623 non-native structures of 31 globular proteins and a solution of the problem based upon the simulated annealing algorithm.This simulated annealing algorithm is indispensable for developing and testing highly refined empirical potential functions.

Effects of AlN Layer and Impurities on Optical Properties of GaN

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

2005, 21(1):  78-82. 

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The effects of the incorporated oxygen and the different buffer layers on the optical properties and surface morphology of GaN were studied.The results show that the decrease of the concentration of the incorporated oxygen has no effect on the surface morphology, but improves the optical properties.While the introduction of the AlN buffer layer makes not only the surface morphology but also the optical properties improve.Both the oxygen contamination from the nitrogen source and the resulted morphology are directly related to the line width of the low-temperature photoluminescence(PL) spectra.

Preparation, Characterization of Hydrotalcites and the Catalytic Properties in Synthesis of o-Phenylphenol over Pt/CHT

YANG Piao-ping, WANG Zhen-lü, YU Jian-feng, LIU Qing-sheng, XUE Bin, ZHANG Zuo-wang, WU Tong-hao

2005, 21(1):  83-87. 

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Mg/Al mixed oxides with molar ratios of 2_6 of Mg to Al used as supports for platinum catalysts were obtained by the thermal decomposition method.The effect of the composition of the mixed oxides on the physicochemical properties was studied by TPD, nitrogen sorption, XRD and TG-DTA characterization methods.The synthesis of o-phenylphenol(OPP) from a dimer(obtained from cyclohexanone condensation) was investigated over Pt/CHT catalysts and compared with those over Pt/MgO and Pt/Al₂O₃ catalysts.These catalysts show a high activity and selectivity for OPP, with a conversion reaching 93.8% and a selectivity reaching 87.9% in some experiments.For Pt/CHT_x catalysts, the calcined hydrotalcites exhibited strong base sites, which were necessary to catalyze the synthesis of OPP.

Effect of Solvents on Oxidation of 1,1′-Bi-2-naphthol

SONG Ji-guo, SHEN Pei-kang

2005, 21(1):  88-91. 

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A novel biomimetic catalyst of complex Cu(p-OTs)₂/ ethanolamine(1∶1) was used to oxidize 1,1′-bi-2-naphthol into xanthene derivatives with a relative high yield in a mixed solvents of dimethyl sulfoxide(DMSO) and CH₃OH.The studies on the effect of some solvents on the yield of xanthene derivatives indicates that the yield reduces dramatically with the increase of the content of H₂O in the mixed solvents of H₂O and DMSO.No product can be obtained when the content of H₂O is up to 70%.The cyclic voltammetric study demonstrated that the copper ion in complex Cu(p-OTs)₂/ethanolamine(1∶1) is reduced via a two-step one-electron reduction process from Cu(Ⅱ) to Cu in the mixture of DMSO and H₂O.Water as a poor solvent in respect to the reactants probably hampered the coordination of 1,1′-bi-2-naphthol to copper/amine complex and led to the insufficient catalytic efficiency of complex Cu(p-OTs)₂/ethanolamine(1∶1).

Reaction Mechanism and Kinetics for HCCO Radical with NO

LIU Peng-jun, PAN Xiu-mei, CHANG Ying-fei, SU Zhong-min, WANG Rong-shun

2005, 21(1):  92-95. 

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The mechanism and dynamical properties for the reaction of HCCO radicals with NO were investigated theoretically.The minimum energy paths(MEP) of the reaction were calculated by using the density functional theory(DFT) at the B3LYP/6-311+G^** level, and the energies along the MEP were further refined at the QCISD(T)/6-311+G^** level.It is found that the reaction mechanism of the title reaction involves three channels, producing HCNO+CO, HONC+CO and HCN+CO₂ products, respectively.Channel 1 is the most favorable path.The rate constant for channel 1 were calculated over a temperature range of 800-2500 K by using the canonical variational transition-state theory(CVT).The rate constant for the main path is negatively dependent on temperature, which is a characteristic of radical reactions with negative activation energy, and the variational effect for the rate constant calculation is small in the whole temperature range.

A Density Functional Study of Small (NiTi)_x Clusters with x=1-3

TAN Kai, GU Yong-bin, LIN Meng-hai

2005, 21(1):  96-99. 

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Systematic studies on the geometry, electronic structure and vibrational properties of small (NiTi)_x clusters with x=1-3, within the framework of the density functional theory, were performed in this work.The electronic structure analyses were used to investigate the bonding between the early-late(EL) transition metals in their alloy.The results of our calculations have been used to predict (NiTi)_x clusters structure for the ground state and confirm that s-electron density is transferred from Ti atoms to Ni atoms followed by the back donation of electrons through the d-orbital.The study provides a fragment approach based on the isolobal analogy that NiTi molecular fragments play a significant role in forming clusters.

Thermal Behavior, Non-isothermal Decomposition Reaction Kinetics of Copper(Ⅱ) Salt of 4-Hydroxy-3,5-dinitropyridine and Its Application in Propellant

CHEN Pei, ZHAO Feng-qi, LUO yang, HU Rong-zu, GAO Sheng-li, ZHENG Yu-mei, DENG Min-hi, GAO Yin

2005, 21(1):  100-103. 

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The thermal behavior and kinetic parameters of the major exothermic decomposition reaction of the title compound in a temperature-programmed mode were studied by means of TG-DTG and DSC.The critical temperature of thermal explosion was calculated.The effect of the title compound on the combustion characteristic of composition modifier double base propellant containing RDX was explored with a strand burner.The results show that the kinetic model function in differential forms, the apparent activation energy(E_a) and the pre-exponential factor(A) of the major exothermic decomposition reaction are 3(1-α)[-ln(1-α)]^2/3, 190.56 kJ/mol and 10^13.39 s^-1, respectively.The critical temperature of thermal explosion of the compound is 353.08 ℃.The kinetic equation of the major exothermic decomposition process of the title compound at 0.1 MPa could be expressed as dα/dT=10^14.65(1-α)[-ln(1-α)]^2/3 e^{-2.2920×104/T}.As an auxiliary catalyzer, the title compound can help the main catalyzer of lead salt of 4-hydroxy-3,5-dinitropyridine to accelerate the burning rate and reduce the pressure exponent of RDX-CMDB propellant.

Synthesis, Crystal Structure and Properties of Complex VO(C₁₀H₉NO₃)(C₁₃H₁₀NO₂)

MA Dong-sheng, GAO Shan, HUO Li-hua, GAO Jin-sheng, ZHAO Jin-gui

2005, 21(1):  104-108. 

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Complex VO(C₁₀H₉NO₃)(C₁₃H₁₀NO₂)(C₁₀H₉NO₃^2-=N-salicylidene-L-alaninate, C₁₃H₁₀NO₂^-=N-phenylbenzohydroxamate) was synthesized and characterized by means of elemental analysis, IR, UV, ¹H NMR spectroscopies, cyclic voltammetry and single crystal X-ray diffraction.The complex crystallized in a monoclinic system with space group P2₁ and crystal cell parameters a=0.9720(1) nm, b=1.8274(2) nm, c=1.2542(1) nm, β=104.868(9)°, V=2.1532(4) nm³, M_r=470.34, Z=2.The two oxygen atoms and the one nitrogen atom of the tridentate Schiff base ligand and the one oxime oxygen atom of the hydroxamate ligand coordinate to the vanadium atom, forming an equatorial plane, the two axial positions are respectively occupied by the oxygen atom of the oxovanadium and the carbonyl oxygen atom of the hydroxamate and the vanadium atom exhibits a distorted octahedral VO(ONO)(OO) coordination sphere.The ¹H NMR spectrum suggests that the two isomers, endo and exo in a molar ratio of 1/1.7, coexist in the solution of the title complex in CDCl₃.There exists a quasi-reversible one-electron redox reaction corresponding to V^Ⅴ/V^Ⅵ couple in the three non-aqueous solvents, and the redox potential E_1/2 of the title complex substantially shifts in the direction of the positive voltage increase in the order: CH₂Cl₂＜CH₃CN＜DMF.

Synthesis and Thermal Crosslinking Behavior of Poly(aryl ether ketone)s Containing 1,4-Naphthalene Moieties

NIU Ya-ming, ZHANG Yun-he, CHEN Xing-bo, WANG Gui-bin, JIANG Zhen-hua

2005, 21(1):  109-113. 

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A new monomer, 1,4-bis(4-fluorobenzoyl) naphthalene(compound 2) was synthesized via a two-step reaction.1,4-Naphthalenedicarboxylic acid chloride(compound 1) was prepared by using the acyl chlorization reaction of 1,4-naphthalenedicarboxylic acid with thionyl chloride.The Friedel-Crafts acylation of compound 1 with fluorobenzene afforded compound 2 in a 80% yield.The polycondensation of compound 2 with various bisphenols in tetramethylene sulfone(TMS) in the presence of excess potassium carbonate as a condensation reagent was carried out at 210 ℃ to quantitatively afford the corresponding poly(aryl ether ketone)s(compounds 3_8) containing 1,4-naphthalene moieties.Thermal analyses showed that the polymers have T_g values ranging from 496 to 500 K and are thermally stable in air with initial mass loss above 500 ℃.These novel polymers exhibited an excellent solubility in organic solvents including NMP, DMAc, and chloroform, etc.In addition, the glass transition temperatures of these polymers increased and the polymers became insoluble in chloroform after treated at 260 ℃, indicating the occurrence of a thermal crosslinking reaction.

Preparation and Characterization of Acylated Chitosan

LI Ming-chun, LIU Chao, XIN Mei-hua, ZHAO Huang, WANG Min, FENG Zhen, SUN Xiao-li

2005, 21(1):  114-116. 

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Fully acylated chitosan and N, N-diacyl chitosan were prepared.The products were characterized by elemental analysis, FTIR and ¹H NMR.The experimental results indicate that the average degree of acylation depends on the volume ratio of pyridine to chloroform in the reaction medium, the chain length of the acylation agent used, and the molecular weight of chitosan raw materials.The XRD measurements were carried out for pure chitosan, fully acylated chitosan and N, N-diacyl chitosan to verify the crystallinity change caused by the acylation.

Investigation of Inclusion Complexes Between α-Cyclodextrin and Ferrocene by ESI-MSn and Cyclic Voltammetry

GUO Li-min, LIU Zhi-qiang, LIU Shu-ying

2005, 21(1):  117-118. 

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Synthesis, Characterization, Crystal Structure and Stability of a Ternary Cu(Ⅱ) complex with 1,10-Phenanthroline and L-Valinate

ZHOU Xiao-hua, LE Xue-yi, LONG La-sheng, CHEN Shi

2005, 21(1):  119-122. 

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One-dimensional Chain Dibenzo-18-crown-6 Complex:[K(DB18-C-6)]₂[Pt(SCN)₆]·2H₂O·C₂H₄Cl₂ Assembled by Cation-π Interactions

ZHU Yue-hua, DU Mao-xi, LI Da-cheng, WANG Da-qi, DOU Jian-min

2005, 21(1):  123-126. 

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