Table of Content

24 August 2006, Volume 22 Issue 4

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Articles

Solvothermal Synthesis and Characterization of (NH₃ CH₂ CH₂ NH₃)HgSnS₄ with a Column Structure

WANG Yan-yan, BAIYIN Meng-he, JI Shou-hua, LIU Xiao-yang, AN Yong-lin, NING Gui-ling

2006, 22(4):  411-414. 

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A compound (NH₃CH₂CH₂NH₃)HgSnS₄ with a column structure was synthesized solvothermally and characterized by X-ray single-crystal diffraction. This compound crystallizes in the monoclinic space group C2/c with a=1.3863(6) nm, b=0.6640(3) nm, c=2.3198(10) nm, β=106.168(7)° and Z=8. It consists of anionic columns of [HgSnS₄]_∞^2- that are interrupted by cationic columns of [EnH₂]²⁺ . Its thermal and optical properties were studied.

Synthesis and Structure of a Novel Supramolecular Compound [Co(2,2'-bipy)(H₂O)₄][trans-1,4-chdc] and Separation of Isomer of 1,4-Cyclohexanedicarboxylic Acid

YU Miao, LIU Shu-xia, ZHANG Chun-dan, GAO Bo, SUN Chun-yan, XIE Lin-hua, WANG Chun-ling, CHENG Hai-yan

2006, 22(4):  415-418. 

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A supramolecular compound, [Co(2,2'-bipy)(H₂O)₄][trans-1,4-chdc] (compound 1) (2,2'-bipy=2,2'-bipyridine, 1,4-chdcH₂=1,4-cyclohexanedicarboxylic acid), was synthesized and characterized by single-crystal X-ray diffraction analysis, IR spectrometry, TG analysis, and elemental analyses. Single-crystal X-ray diffraction analysis revealed that [Co(2,2'-bipy)(H₂O)₄]²⁺ units and adjacent 1,4-chdc^2-formed a single layer by hydrogen bonding and electrostatic interactions along the ac-plane, and two symmetry-related single layers interacted with each other by hydrogen bonding, resulting in a double layer, which further formed a 3-D structure by π-π stacking. The most attractive structural feature of compound 1 is that 1,4-chdc^2- possesses only trans-conformation although there are both cis- and trans-conformations in the raw material.

5,10,15,20-Tetrakis(p-4-fluorobenzoyloxy)phenyl Porphyrin and Its Transition Metal Complexes

LIU Wei, SHI Tong-shun, LIU Guo-fa

2006, 22(4):  419-422. 

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The properties of porphyrins can be changed through the choice of peripheral substituents and inserted metal ions. To obtain porphyrin complexes with novel structures, 5,10,15,20-tetrakis(p-4-fluorobenzoyloxy) phenyl porphyrin(TFBOPPH₂) and its transition metal complexes {TFBOPPM [M=Mn(Ⅲ), Fe(Ⅲ), Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ)]} were synthesized and characterized by means of UV-Vis, IR photoacoustic spectrometry, ¹H NMR, elemental analyses, molar conductance, and XPS methods. A structure is proposed, in which one porphyrin molecule is coordinated with a transition metal ion in a tetradentate fashion, while the chlorine ion is the balanceable anion in Fe(Ⅲ) and Mn(Ⅲ) complexes.

Optical Spectroscopy Properties of KMgF₃:Eu²⁺ Nanocrystals and Powder Synthesized by Microemulsion and Solvothermal Process

HUA Rui-nian, SUN Hong-jie, JIANG Hui-ming, SHI Chun-shan

2006, 22(4):  423-426. 

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Nanocrystals and powders of KMgF₃ doped with Eu²⁺ were synthesized by the microemulsion method and the solvothermal process, respectively. The emission and excitation spectra of KMgF₃:Eu²⁺ phosphors were measured and compared with those of the samples synthesized through a solid state reaction, Bridgman-Stockbarger method, and mild hydrothermal technique. The KMgF₃:Eu²⁺ samples synthesized by means of the microemulsion method and the solvothermal process show only a sharp emission peak located at 360 nm in the emission spectra, which arises from the f→f(⁶P7/2→⁸S7/2) transition of Eu²⁺. The broad emission bands appear at 420 nm, which arises from Eu²⁺←O^2- cannot be observed(in the mild hydrothermal and single crystal samples, the emission peak at 420 nm besides the emission of Eu²⁺ at 360 nm is observed). In the excitation spectrum of the KMgF₃:Eu²⁺ samples synthesized by the microemulsion method and the solvothermal process, the excitation peaks show an intensive blue shift. The blue shift can be attributed to the lower oxygenic content in the KMgF₃:Eu²⁺ samples synthesized by the microemulsion method and the solvothermal process.

Dependence of Performance of Organic Light-emitting Devices on Sheet Resistance of Indium-tin-oxide Anodes

ZHOU Liang, ZHANG Hong-jie, YU Jiang-bo, MENG Qing-guo, PENG Chun-yun, LIU Feng-yi, DENG Rui-ping, PENG Ze-ping, LI Zhe-feng

2006, 22(4):  427-431. 

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The dependence of the performance of organic light-emitting devices(OLEDs) on the sheet resistance of indium-tin-oxide(ITO) anodes was investigated by measuring the steady state current density brightness voltage characteristics and the electroluminescent spectra. The device with a higher sheet resistance anode shows a lower current density, a lower brightness level, and a higher operation voltage. The electroluminescence(EL) efficiencies of the devices with the same structure but different ITO anodes show more complicated differences. Furthermore, the shift of the light-emitting zone toward the anode was found when an anode with a higher sheet resistance was used. These performance differences are discussed and attributed to the reduction of hole injection and the increase in voltage drop over ITO anode with the increase in sheet resistance.

Preparation and Characterization of Fe/Al₂O₃ Nanocomposites

LI Hai-bo, LIU Mei, LU Yang, XU Ying, YU Wen-xue

2006, 22(4):  432-434. 

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Fe₂O₃/Al₂O₃ nanocomposites prepared by using the sol-gel technique were reduced in H₂ atmosphere at different temperatures, and the corresponding Fe/Al₂O₃ nanocomposites were obtained after the reduction of Fe₂O₃/Al₂O₃ nanocomposites at 1173 K. The structures and properties of the specimens were studied by X-ray diffraction(XRD), M(o)ssbauer spectroscopy(MS), and vibrating sample magnetometry(VSM). The results show that the reduction temperature has a significant influence on the structure, the grain size, and the magnetic properties of the specimens.

Analysis of Equilibrium and Kinetics of Chromium-Fluoride Complexation from Spectroscopic Data via Chemometrics Methods

CHEN Kai, ZHU Zhong-liang, ZHANG De-jun

2006, 22(4):  435-438. 

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The complexation of Cr³⁺ with F^- undergoes a multistep reversible process. An approach to research the involved equilibria and kinetics using suitable chemometrics methods to the online measured UV-Vis spectra is proposed. By investigating the equilibrium spectra of the complexes at different molar ratios of M to L(metal to ligand) and 50 ℃, the result of Principal Component Analysis(PCA) shows that three complexes, ML, ML₂ and ML₃, can be formed under the research conditions. The spectrum of each complex was then analyzed and the accumulated equilibrium constants were calculated by applying Target Testing Factor Analysis(TTFA). Meanwhile, a reactive intermediate was observed before the formation of ML_x during the specific kinetic study at 15 ℃. The equilibrium constant and spectrum of the intermediate as well as the rate constants were all resolved by using TTFA.

Application of Density Functional Theoretic Descriptors to Quantitative Structure-Activity Relationships with Temperature Constrained Cascade Correlation Network Models of Nitrobenzene Derivatives

CUI Xiu-jun, ZHANG Zhuo-yong, YUAN Xing, ZHANG Jing-ping, LIU Si-dong, GUO Li-ping, Peter de B. HARRINGTON

2006, 22(4):  439-442. 

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A temperature-constrained cascade correlation network(TCCCN), a back-propagation neural network(BP), and multiple linear regression(MLR) models were applied to quantitative structure-activity relationship(QSAR) modeling, on the basis of a set of 35 nitrobenzene derivatives and their acute toxicities. These structural quantum-chemical descriptors were obtained from the density functional theory(DFT). Stepwise multiple regression analysis was performed and the model was obtained. The value of the calibration correlation coefficient R is 0.925, and the value of cross-validation correlation coefficient R is 0.87. The standard error S=0.308 and the cross-validated(leave-one-out) standard error S_cv=0.381. Principal component analysis(PCA) was carried out for parameter selection. RMS errors for training set via TCCCN and BP are 0.067 and 0.095, respectively, and RMS errors for testing set via TCCCN and BP are 0.090 and 0.111, respectively. The results show that TCCCN performs better than BP and MLR.

Expression Levels of RFP in Normal and Cancer Human Tissues via Real-time RT-PCR Detection

JIN Xiang-qun, ZHANG Jing-min, XU Hui, ZHANG Han-qi

2006, 22(4):  443-446. 

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Ret finger protein(RFP) is a member of the tripartite motif family, which is characterized by a conserved RING finger of motif, a B-box, and a coiled-coil domain(they are called RBCC generally). Although RFP was known to be an oncogene when its RBCC moiety was connected with a tyrosine kinase domain by DNA rearrangement, its biological function was not well defined. In this study, by using real-time RT-PCR, the RFP expressions in human and mouse normal tissues, and in the cervical squamous cell carcinoma, endometrial adenocarcinoma, gastric adenocarcinoma, esophageal squamous cell carcinoma, and brain cancer tissues were analyzed. The result of the study proved that the highest level of mRNA reverse transcription appeared in the normal testical tissue, whereas that in other normal tissues of human and mice were low. The mRNA reverse transcription level of RFP was higher in the endometrial adenocarcinoma tissue than in the cervical squamous cell carcinoma tissue; the mRNA reverse transcription level of RFP in the gastric adenocarcinoma tissue was significantly higher than that in the esophageal squamous cell carcinoma tissue. It was also found that the mRNA reverse transcription level of RFP in the brain cancer tissue was higher than that in the normal brain tissue. These results suggested that RFP could possibly be a useful molecular target for the development of new therapeutics for malignant tumors.

GIS-based Analysis of Main Air Pollutants of Changchun City in Summer

JING Nan, XIA Bin, JING Ti-song

2006, 22(4):  447-450. 

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To gain a better understanding of the characteristics of air pollution of Changchun city, P. R. China, in summer, the analytical methods of geographical information system(GIS) and statistical analysis software SPSS were applied to the analysis of the monitored concentrations of SO₂, NO₂, and O₃ in July of 2002 to 2004 in Changchun city. The results obtained show that the average hourly O₃ concentrations in July 2002 and 2004 were higher than the first-level hourly standard of China. At the same time, the dynamic distribution of the O₃ concentration and the relationship between the concentration of O₃ and that of NO_x were studied. The air quality evaluation result of Changchun city indicates that the southwest of this city was heavily polluted during the monitored period.

Tetra-n-butylammonium Hydroxide: an Efficient Catalyst for N-Alkylation of Pyrimidines and Purines

ZHANG Zhi-li, ZHOU Shou-xin, WANG Xiao-wei, WANG Hong-tao, CHEN Yan-li, LIU Jun-yi

2006, 22(4):  451-454. 

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An efficient procedure for N-alkylation of pyrimidines and purines in the presence of tetra-n-butylammonium hydroxide(TBAH) is described. The method is very practical and the alkylation can occur at room temperature and the yields of the N-alkyl pyrimidines and purines were found to be excellent.

Glucuronidation of Two Novel Metabolites of Benproperine with Trichloroacetimidate Donor

LI Yan, HARA Osamu, MAEBA Isamu, ZHONG Da-fang

2006, 22(4):  455-458. 

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The glucuronide metabolites of benproperine were synthesized from mono-hydroxylate metabolites of benproperine that were treated with methyl(2,3,4-tri-O-acetyl-1-O-trichloroacetimidoyl)-α-D-glucopyranuronate with BF₃·Et₂O as the promoter followed by basic hydrolyzation with Na₂CO₃. The form of basic acceptors, the order of addition, and the promoter are all important variables in this glucuronidation. The salt form of the basic acceptor was found to be better than its free form for glucuronidation with a Lewis acid as the promoter. Two mono-hydroxylated benproperines were synthesized from 2-benzylphenol in three steps.

Synthesis and Antibacterial Activity of Novel Oxazolidinone Analogs Containing Substituted Thiazole/Fused-Bicyclic Groups

ZHAI Xin, ZHAO Yan-fang, WANG Jia, HONG Wei, HUANG Liang, GONG Ping

2006, 22(4):  459-464. 

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Sixteen novel oxazolidinone analogs containing substituted thiazole/fused-bicyclic(imidazo[1,2-b] pyridazine/imidazo[2,1-b]thiazole) groups were designed and synthesized. A new method for the preparation of the key intermediate compound 11 was proposed. The structures of the target compounds were confirmed by ¹H NMR, IR and MS, and their in vitro antibacterial activities against staphylococcus aureus were evaluated. Among them, compound 16a displays a promising antibacterial activity comparable to that of linezolid.

Synthesis, Structure and Biological Activities of 2-(1H-1,2,3-Benzotriazol-1-yl)-1-(4-methylphenyl)-2-(1H-1,2,4-triazol-1-yl)-1-ethanone

WAN Jun, LI Chun-li, LI Xue-mei, ZHANG Shu-sheng

2006, 22(4):  465-467. 

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The title compound was synthesized and characterized by IR, ¹H NMR, elemental analysis and single crystal X-ray diffraction analysis. Its biological activities were also tested. The results show that the title compound reveals inhibiting activities towards wheat gibberellin, apple ringspot, tomato early blight, peanut cercospora arachidicola and stem wilt of asparagus.

Syntheses and Vasodilatory Activities of New Pyrazolo[4,3-d]pyrimidin-7-ones

ZHAO Yan-fang, ZHAI Xin, CHEN Jiao-yue, GUO Shu-chun, GONG Ping

2006, 22(4):  468-473. 

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A series of novel pyrazolo[4,3-d]pyrimidin-7-ones was designed and synthesized in order to find new potent phosphodiesterase 5 inhibitors(PDE5). The structures of all the compounds were confirmed by IR, ¹H NMR and MS; their in vitro vasodilatory activities were tested on isolated rabbit aortic spiral strips. Among them, compound Ⅹ3 displays a significant vasodilatory activity, which is more potent than verapamil.

Biosensor Based on TTF@SiO₂ Nanoparticles as Electron Transfer Mediator for the Determination of Glucose

LI Xiao-hua, XIAN Yue-zhong, MIN Hong, LI Chen-xin, XIE Zong-hong, ZHANG Fen-fen, JIN Li-tong

2006, 22(4):  474-478. 

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Tetrathiafulvalene(TTF) was doped in an SiO₂ network and the resulting nanocomposite was used as a mediator for the selective detection of glucose. The uniform TTF-doped silica(TTF@SiO₂) nanoparticles were prepared by the water-in-oil(W/O) microemulsion method, and were characterized by transmission electron microscopy(TEM). The core-shell structure TTF@SiO₂ could prevent TTF from leaching out into an aqueous solution. Combined with chitosan(CHIT), which serves as a scaffold for glucose oxidase and nanocomposite immobilization, the GCE/TTF@SiO₂-CHIT-GOx biosensor was developed. Under optimal conditions, the biosensors exhibit a linear range of 1.0×10-5^-5×10^-3 mol/L with a detection limit down to 5.0 μmol/L(S/N=3). The excellent selectivity, sensitivity, and stability of the glucose biosensor show its potential for practical applications.

Sensitive and Rapid Quantification of Felodipine by High-performance Liquid Chromatography-tandem Mass Spectrometry(HPLC-MS/MS) and Its Pharmacokinetics in Healthy Chinese Volunteers

LI Yan-yan, YIN Yi-zi, SUN Zhi-hui, LI Xin, HU Li-gang, LI Peng-fei, ZHONG Da-fang

2006, 22(4):  479-483. 

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To investigate the pharmacokinetics of felodipine in the plasma of healthy Chinese volunteers, 30 healthy volunteers received a single oral dose of 5 mg of extended release felodipine tablets. The felodipine was extracted from the matrix with a liquid-liquid extract procedure and analyzed by high-performance liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring(MRM) mode using an electrospray ion source with positive ion detection. The method was validated over a felodipine concentration range of 0.05-10.00 ng/mL in human plasma. Its main pharmacokinetic parameters values were: ρ_max=(1.67±0.84) ng/mL, occurring at (3.93±2.49) h; the plasma elimination half-life: (23.08±9.48) h and the area under the plasma concentration versus time curve: (29.94±14.39) ng·h/mL. The validation results demonstrated that this method showed a satisfactory precision and accuracy across the calibration range. The procedure involved minimal drug administration, sample preparation, and a 2.5-min chromatographic run time. It was well suited to clinical studies of the drug involving large numbers of samples.

Photoelectrochemical Character of TiO₂ Nanocrystalline Electrodes Sensitized by Aluminum Phthalocyanines Modified with Sulfonate Groups

PAN Kai, LIU Zhao-yue, WANG Geng, BAI Yu-bai, LI Tie-jin

2006, 22(4):  484-487. 

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Particular kinds of TiO₂ nanocrystalline electrodes were sensitized by aluminum phthalocyanines modified with sulfonate groups [Al(OH)PcS_n]. It was found that in the red region, the electrodes show obvious photoelectrical responses. The surface photovoltage spectra and photocurrent action spectra indicate that in the red region, the monomers of aluminum phthalocyanines have a greater influence on the determination of the photoelectrical response of TiO₂ electrodes than the dimers. The dye-sensitized solar cells were obtained by using the aluminum phthalocyanines-sensitized TiO₂ electrodes and Pt electrodes, which have an open circuit photovoltage of 360 mV, a short circuit photocurrent of 39.4 μA/cm², a fill factor of 0.54 and a maximum power output of 7.65 μW/cm² under a light intensity of 50 mW/cm².

Adsorption and Vibration of Cl Atoms on Ni Low-index Surfaces

ZHANG Jing, DIAO Zhao-yu, WANG Ze-xin

2006, 22(4):  488-492. 

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The 5-parameter Morse potential(5-MP) of the interactions between Cl atoms and Ni surfaces was constructed. The adsorption and diffusion of Cl atoms on Ni low index-surfaces were investigated with 5-MP in detail. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, eigenvalues for vibration, etc. were obtained. The calculated results show that chlorine atoms are likely to be adsorbed on the high symmetry sites. Cl atoms locate on the four-fold hollow sites of the intact Ni(100) surface, while they tend to occupy three-fold sites on the Ni(111) surface. The four-fold hollow sites are the most stable adsorption sites on the Ni(110) surface for Cl, although the three-fold sites and the long-bridge sites are stable adsorption sites on the Ni(110) surface for the atoms of the first and second periods. For the Cl-Ni surface adsorption system, the surface binding energy of a Cl atom is relevant to the coarse degree of the cluster surface, and the binding energies have an order of Ni(111)＜Ni(100)＜Ni(110).

Electrochemistry of Hydroquinone Derivatives at Metal and Iodine-modified Metal Electrodes

HOU Peng, HAN Dong-xue, NIU Li, LIN Hai-bo

2006, 22(4):  493-499. 

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The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The results show that the hydroquinone derivatives are adsorbed on a gold surface with vertical orientation, which makes the electron transfer between the bulk species and the electrode surface easier than that in the case of flat adsorption of hydroquinone derivatives that occurs at a platinum electrode. The formation of the vertical conformation and the rapid process of electron transfer were also confirmed by quantum chemistry calculations. In addition, the pre-adsorbed iodine on the electrodes played a key role on the adsorbed configuration and electron transfer of redox species.

Identification and Kinetics Study on the Transformation of Mevinolin in Acidic Alcohol Solution by High-performance Liquid Chromatography with Photodiode Array Detector or Mass Spectrometry

LI Yong-guo, LIU Hong, ZHANG Fang, WANG Zheng-tao, HU Zhi-bi

2006, 22(4):  500-504. 

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Mevinolin is one of the earlier statin drugs which is effective for the treatment of hypercholesterolemia, as an inhibitor of the HMG-CoA reductase. The transformations of mevinolin in acidic alcohol(such as ethanol, methanol and isopropanol) solutions caused by solvent effects were revealed in the present article. The solvates, that is, mevinolinic methyl ester, mevinolinic ethyl ester and mevinolinic isopropyl ester, were identified by LC/PDA and LC/MS. The kinetics parameters of the transformations caused by solvent effects, such as the observed rate constant of mevinolin(k_obs), the maximum concentration(c_max), and its corresponding maximum time(t_max, time for the acid form to reach the maximum concentration) of mevinolinic acid, are discussed. The influencing factors, such as the kind of solvents, the acidic concentration, the initial mevinolin concentration, and the water content as well as temperature were investigated. Two kinds of comparative reactions, hydrolysis and alcoholysis, of mevinolin in solution were studied. This detailed study on the kinetics of mevinolin transformations is valuable and meaningful for the purification, preparation, injection manufacturing, extraction, storage, etc., of mevinolin or other similar compounds. This work provides useful information for the quality control of mevinolin and mevinolin-like drugs as well.

Spectral Properties and Photochromic Characteristics of Spiropyran Dyes

SHEN Kai-hua, HAN Jian-guo, ZHANG Gang, CHOI Dong-hoon

2006, 22(4):  505-509. 

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A bis-benzospiropyran(BBSP) and nitro-substituted indoline spirobenzopyrans(SBP) were prepared by following a simple procedure. The reaction mechanism of synthesizing bis-benzospiropyran is discussed. A comparative analysis of the spectral and photochromic properties between SBP and BBSP was carried out with the aid of a PMMA film. The results indicate that chemical structures and UV irradiation played an important role in the spectral and photochromic properties of SBP and BBSP, which would readily affect λ_max of the colored forms and the reversibility. The IR spectra and ¹H NMR spectra of these compounds are used to interpret the photochromic phenomena under different UV irradiation and determine the configurations of SBP and BBSP.

Packing Structures of Thiophene Dimers and Their Effects on Excitation Energies of Thiophene Dimers

LI Ling, WEI Yong-de, LIU Ji-hong, YANG Lu-qing, ZHANG Gui-ling

2006, 22(4):  510-514. 

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The packing structures of thiophene dimers and their effects on excitation energies of thiophene dimers were studied by employing MP2/6-31+G^* and TDDFT calculations. Twelve optimized dimers with different orientations were obtained by means of MP2/6-31+G^* optimizations. Among them, five T-shaped and three π-stacked thiophene dimers are local minima in energy. The result shows that the preferable conformation of thiophene dimers is the T-shaped packing, which is in agreement with the results in references. All the excitation energies of both T-shaped dimers(5.34-5.48 eV) and π-stacked dimers(5.15-5.18 eV) are lower than that of the isolated thiophene(5.68 eV), indicating that inter-ring interactions decrease the excitation energies.

Effects of Cerium Doping at Ti Sites and Europium Doping at Ba Sites on Dielectric Properties of BaTiO₃ Ceramics

ZHANG Ya-min, SUN Xiu-yun, LU Da-yong

2006, 22(4):  515-519. 

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Two special rare earth elements cerium and europium were chosen to conduct chemical modification of the BaTiO₃ structure. The cold-pressing ceramic processing technique was used to prepare barium titanate ceramics doped with Ce at Ti sites and with Eu at Ba sites on the base of formulas Ba(Ti_1-xCe_x)O₃(x=0.05, 0.10)(CBT) and(Ba_1-yEu_y)Ti_1-y/8O₃(y=0.05, 0.10)(EBT). Associated with structures and microstructures, the effects of cerium and europium doping on dielectric properties of BaTiO₃ ceramics were discussed. The CBT ceramics exhibit a pseudo-cubic perovskite structure, while the EBT ceramics exhibit a tetragonal perovskite structure with the exception of the existence of a small percentage of the Eu₂Ti₂O₇ phase. The Curie peak of BaTiO₃ shifts towards room temperature at rates of 3 ℃/mol Ce atoms and 10 ℃/mol Eu atoms(Eu≤5%), respectively. Compared with the CBT ceramics, the EBT ceramics show significant advantages, such as a narrow fine grain size distribution(1 μm), a lower porosity and a higher density(5.85 g/cm³), more stable dielectric-temperature dependence(ε'=1600-1800 at t＜50 ℃) and a lower dissipation factor(＜0.05). The stability of dielectric constant with frequency in BaTiO₃ can extend to 10⁷ Hz due to Ce and Eu doping.

Theoretical Study of the Photochemical Reaction Mechanism of Bicyclo[4.1.0]heptane

WANG Yan-xia, YE Song

2006, 22(4):  520-523. 

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The photochemical reaction of bicyclo[4.1.0]heptane was studied at the complete active space SCF(CASSCF) level with a 6-31G* basis set. A multireference MP2 algorithm that has been implemented in the Gaussian program was used to correct the energetics for the dynamic correlation. Starting from the Franck-Condon excitation of bicyclo [4.1.0] heptane, the reaction is via two bonds' breakage to give rise to 1,6-heptdiene. One internal conversion(IC) and two intersystem crossing points(ISC) were located and are discussed separately. The reaction proceeds to its own characteristic product on the ground state.

TG-FTIR Study on Corn Straw Pyrolysis-influence of Minerals

YANG Chang-yan, LU Xue-song, LIN Wei-gang, YANG Xue-ming, YAO Jian-zhong

2006, 22(4):  524-532. 

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In order to study the effect of minerals on biomass pyrolysis, experiments on pyrolysis of corn straw with different pretreatment methods were performed by using a thermogravimetric analyzer(TGA) coupled with a Fourier transform infrared(FTIR) spectrometer. The pretreatment methods included water washing and acid washing. The experimental results show that acid washing can remove almost all K⁺ and 78% of Ca²⁺, while water washing only removes most of K⁺. The existence of K⁺ and Ca²⁺ obviously favors the formation of compounds containing carbonyl groups and CO₂, but it will decrease the yields of compounds containing C-O-C groups. However, the formation of H₂O, CO and CH₄ are slightly affected by the removal of inorganic ions. With regard to the structure of the metal ions-adsorbed cellulose characterized by IR analysis, it can be considered that there is an "ion force" between metal ions and cellulosic biomass. The results of thermal kinetic analysis show that this force can make the reaction activation energy of the biomass pyrolysis decrease. A new mechanism is proposed for explaining the effect of inorganic ions on cellulose pyrolysis.

Vapour-phase O-methylation of Catechol with Methanol on Ti-containing Phosphate Catalysts

ZHU Xiao-mei, LI Xue-mei, LIU Gang, ZOU Xiu-jing, WANG Yan-li, JIA Ming-jun, ZHANG Wen-xiang

2006, 22(4):  533-536. 

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Ti-containing phosphate(Ti-P-O) catalysts with different molar ratios of P to Ti(0-2.0) were synthesized and characterized by XRD, N₂-adsorption/desorption, IR and temperature-programmed desorption(TPD) methods. The catalytic properties of Ti-P-O samples in the vapor-phase O-methylation of catechol with methanol were also studied. The catechol conversion increases with the increase of the molar ratio of P to Ti in a range of 0-0.33, while a further increase in the P content leads to a decrease of the catalytic activity. Meanwhile, the selectivities of the catalysts to the main product(guaiacol) increase gradually with the increase of the molar ratio of P to Ti. The presence of relatively strong Lewis acidic and/or basic sites in the P-free catalyst should be responsible for the formation of C-alkylation products. The weak acid-base characteristics of the catalysts are favourable for the mono-O-methylation of catechol. In comparison with the Lewis acidic sites, the Br(o)nsted acidic sites on the catalysts are more active for the title reaction.

Synthesis of Calix[4]resorcinarene Core Dendrimers with Peripheral Salicylideneimine Functional Groups

HAN Jun, GE Yun, YAN Chao-guo

2006, 22(4):  537-542. 

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First to third-generation calix[4]resorcinarene core dendrimers, compounds 4a, 4b, 7a, 7b, 10a and 10b, were prepared via the divergent method in seven steps with the corresponding tetraphenyl- and tetra(hydroxyphenyl)calix[4]resorcinarenes(compounds 1a, 1b) as the starting material. The repeat units of the polyamidoamines of these dendrimers were obtained by the ammonolysis of ethyl calixarylacetates 2a and 2b with 1,3-diaminopropane, that is, amide derivatives with terminal amino groups, which in turn reacted with ethyl acrylate to give a higher generation of ester derivatives. The structures of these dendrimers were characterized by IR, ¹H and ¹³C NMR spectrometries. The crystal structure of compound 2b with 12 ethoxycarbonylmethoxy groups was determined by X-ray analysis.

A New Method of Photopatterning with LB Films Based on a Chemically Amplified Mechanism

LI Tie-sheng, Masaya Mitsuishi, Tokuji Miyashta

2006, 22(4):  543-546. 

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A new approach to introducing a photoacid generator(PAG) into Langmuir-Blodgett(LB) films to draw photopatterns as a lithographic process is described here. The chemically amplified positive-tone resist system used here consists of two components: a copolymer, poly(dodecrylacrylamide-co-4-t-butyloxylvinyl-phenylcarbonate)[P(DDA-t-BVPC53)] and a PAG, tri(2,3-dibromopropyl) isocyanurate(TDBPIC). In the two-component system, the acid generated by the PAG catalyzes the deprotection reaction of P(DDA-t-BVPC53), to remove the tert-butoxycarbonyl group(t-BOC) in the exposed region during the postexposure baking process, thus rendering the exposed region soluble to alkaline aqueous solvents to form a positive tone. Photolithographic properties of the LB films have been evaluated. The patterns can be resolved with a resolution of 1 μm line width by UV irradiation, followed by development with an alkaline solution. The LB films can be used to generate etched gold relief images on a glass substrate via an aqueous iodide, like ammonium iodide, in alcohol/water as the etchant. The etch resistance of such LB films is sufficiently good, allowing patterning of a gold film suitable for photomask fabrication.