Sep 2007, Volume 2 Issue 3

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  • WU Yikang, WU Yu-Lin
    The major progress in organic synthesis since 2005 is briefly surveyed in two parts. The first part deals with some of the most impressive advances in the synthetic methodology, which includes: (1) metal-mediated synthetic reactions, with an emphasis on the olefin metathesis and gold-mediated reactions; (2) free radical-based organic synthesis; (3) synthetic transformations performed in a one-pot  manner involving either tandem reactions or multicomponent reactions; (4) asymmetric reactions catalyzed by metal and organo-catalysts. The major advances in total synthesis of some complex natural products with significant biological activities are presented in the second part, with detailed illustrations of ten selected molecules, including dragmacidin F, abyssomicin C, 11-acetoxy-4-deoxyasbestinin D, pentacycloanammoxic acid, UCS1025A, (−)-merrilactone A, nigellamine A2, (+)-saxitoxin, and Tamiflu (an artificially designed natural product-like molecule). An array of complicated structures of the natural products synthesized over the last two years is also listed to serve as a convenient lead to the original literature for the prospective interested readers.
  • PEI Xianru, WANG Xiaodong, ZHANG Shunli, ZHANG Jingwei, YANG Jianjun, JIN Zhensheng
    Nanotube Li-Ti-O compound with high surface (198.6 m2 · g-1) was prepared by a method involving the treatment of nanotube Na2Ti2O5 · H2O in molten LiNO3 and characterization by means of transmission electron microscopy (TEM), energy-dispersive spectra (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetry-differential thermal analysis (TG/DTG). Results show that the nanotube Li-Ti-O compound prepared by this method involves two crystal phases: spinel Li2Ti2O4 and anatase LixTiO2 (x<0.1). Li+ exhibits different Li1s binding energy in the two crystal phases. In ambient air, the Li-Ti-O compound adsorbs water easily, and the chemically adsorbed water is difficult to remove below 400?C.
  • TSANG Po Keung, ZENG Lixuan
    A rapid and reliable high performance liquid chromatographic(HPLC) method for the simultaneous determination of heterocyclic compounds, namely nicotinic acid, nicotinamide, and 3-cyanopyridine, in industrial effluent is described. A Φ4.6 mm×150 mm, 5 μm C-18 reversed phase stationery phase, and a methanol-acetonitrile-water tertiary mobile phase (20:20:60 v/v) were used for separation. The detection wavelength of a diode array (DAD) was set at 216 nm with a bandwidth of 16 nm. Phenol was used as an internal standard. The regression equations revealed a linear relationship between the concentration of the analytes injected and the peak area detected by DAD. The limits of detection (S/N = 3) ranged from 0.70 to 1.18 mg L-1, the recoveries ranged from 87% to 102% and the precision expressed as % RSD intra-day and inter-day varied from 0.9 to 3.9 and 1.2 to 5.6, respectively. This method is rapid, sensitive and suitable for the monitoring of nicotinic acid, nicotinamide, and 3-cyanopyridine in effluent of related pharmaceutical manufacturing plants.
  • BAI Guoxin, CHEN Lina, WU Liping, YE Mingxin
    A novel compound of butyl crystal violet lactone (BCVL) has been prepared by oxidizing leuco butyl crystal violet lactone (LBCVL), which was obtained by the mixture of N,N-dibutylaniline, ρ-(dibutylamino) benzaldehyde and methyl-m-(dibutylamino) benzoate. The structure of BCVL was characterized by 1H- nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS). The color of BCVL can change reversibly in some acid or alkali solvents. The result of the dissolution experiment showed that solubility of BCVL in organic solvent was improved compared with crystal violet lactone (CVL).
  • LONG Mingce, CAI Weimin, CHEN Heng, XU Jun
    A novel chlorine-doped titanium dioxide catalyst with visible light response was prepared by hydrolysis of tetrabutyl titanate in hydrochloric acid. The catalyst samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Results showed that the doped element of Cl lowered the temperatures of phase transformation of TiO2 from amorphous to anatase and from anatase to rutile. The absorption edge of chlorine-doped TiO2 calcined at 300vH shifted to visible light region. X-ray photoelectron spectroscopy results proved that chlorine existed in the TiO2 crystal lattice as anion. The photocatalytic degradation of phenol showed that under visible light (&lambda;>400 nm) irradiation, the chlorine-doped TiO2 calcined at 300vH displayed the best performance, the degradation ratio of phenol was 42.5% after 120 min.
  • ZHOU Lei, JIANG Huanfeng
    3-Ene-1, 5-diynes are important components of many enediyne antitumor agents and luminescent materials. A stereo-controlled approach to the synthesis of E-enediynes was developed, and it consists of the following two steps: (1) a mild and economical synthesis of dihalo vinyl derivatives via addition of CuBr2 to alkynes; (2) the Sonogashira coupling reaction of the dihalo vinyl derivatives with terminal alkynes to form conjugated enediynes.
  • ZHANG Youwei, ZHAO Jiongxin, WANG Jiaye, JIANG Ming
    According to the new method of preparing core-shell nanospheres developed by our group, by using two monomers, 2-hydroxypropyl methacrylate(HPMA) and vinyl acetate(VAc), two kinds of core-shell nanospheres with poly(?-caprolactone) (PCL) as the core and crosslinked poly(2-hydroxypropyl methacrylate) (PHPMA) or poly(vinyl acetate) (PVAc) as the shell were successfully prepared under similar conditions. After degrading the PCL cores of the two kinds of nanospheres by lipase, the corresponding crosslinked poly(methyl acrylic acid) hollow spheres and crosslinked poly(vinyl alcohol) hollow spheres were obtained. Results indicate that the new method we proposed for preparing core-shell polymeric nanospheres via in-situ polymerization can be generalized to a certain extent, and it is suitable for many systems provided the monomer used is soluble in water, while its corresponding polymer is insoluble in water.
  • GONG Linbo, GONG Shuling, DONG Haiqing, ZHANG Chunlei, CHEN Yuanyin
    The reaction of 4&primer;-hydroxy-4-methyl azobenzene (1) and 1,6-dibromohexane afforded 6-bromo-1-((4- ((4-met hylphenyl)azo)phenyl)oxy)hexane (2), which further reacted with ρ-tert-butylcalix[4]arene to give the calix[4]arene derivative (3) whose lower rim had been modified by the azobenzene photochromic group. The structure of 3 was characterized by 1H-nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS). The fluorescence intensity of compound 3 was two to four times higher than that of compounds 1 and 2 as the azobenzene group concentration in the range of 1.6×10-5 to 8.0×10-4 mol/L, indicating that the fluorescence quantum yield of the azobenzene group had been improved through being attached to the calix[4]arene skeleton. The liquid crystalline behavior of compound 3 was studied by polarized microscopy (POM) and differential scan calorimeter (DSC). Compound 3 exhibited the enchased texture of a smectic liquid crystal from 209.4?C to 219.5?C on heating, while 2 exhibited a liquid crystalline phase from 87.4 to 83.2?C on cooling. It was found that the calix[4]arene skeleton was a good platform for conformation immobilization of azobenzene photochromic group and the formation of liquid crystalline.
  • YANG Yuan, LI Qi, ZHANG Jinnan, SONG Xiaohong, LUO Surong
    Two new inclusion compounds (n-C4H9)4N+C18H13O4- &middo; B(OH)3 (1) and (n-C4H9)4N+C18H13O4- (2) were prepared and characterized by X-ray crystallography. Crystal data: compound 1, monoclinic P2(1)/c, a = 1.569 9(1) nm, b = 0.995 5(6) nm,c = 2.293 3(1) nm, β = 109.962(3)º, Z = 4, and R1 = 0.0434, wR = 0.075 9; compound 2, monoclinic C2/c, a = 1.400 5(3) nm, b = 1.282 1(2) nm, c = 1.765 7(3) nm, β = 100.388(1)º, Z = 4, and R1 = 0.0584, wR = 0.096 6. In the crystal structure of 1, the tetramers formed by two trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (EADA) anions and two boric acid molecules were connected through O H…O hydrogen bonds to generate a channel type host lattice. The tetra-n-butylammonium cations were stacked to give two columns within each channel with cross-sectional size of about 2.30 nm×0.93 nm. In the crystal structure of 2, similar honeycomb host lattices with big size were also formed along the [101] direction by three-dimensional accumulation of EADA anions. The tetra-n-butylammonium cations were accommodated in a zigzag fashion within each channel.
  • YUAN Zhengyong, YUAN Liangjie, SUN Jutang
    After preparing the precursor by a liquid precipitation method, a series of tin-zinc composite oxides with different components and structures were synthesized as the anode materials for lithium ion batteries when the precursor was pyrolyzed at different temperatures. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and electrochemical measurements. The reversible capacity of amorphous ZnSnO3 is 844 mA · h/g in the first cycle and the charge capacity is 695 mA · h/g in the tenth cycle. The reversible capacity of ZnO · SnO2 is 845 mA · h/g in the first cycle and the charge capacity is 508 mA · h/g in the tenth cycle. The reversible capacity of SnO2 · Zn2SnO4 is 758 mA · h/g in the first cycle and the charge capacity is 455 mA &midddot; h/g in the tenth cycle. Results show that amorphous ZnSnO3 exhibits the best electrochemical property among all of the tin-zinc composite oxides. With the formation of crystallites in the samples, the electrochemical property of the tin-zinc composite oxides decreases.
  • LAN Wenjian, LI Houjin
    A new pentacyclic triterpenoid, urs-12-en-29α-oic acid-3β-ol (1), was obtained from the ethanol extract of Chinese herb Oldenlandia cantonensis How. The structure was elucidated by spectroscopy methods, including nuclear magnetic resonance (NMR) (1D and 2D), infrared spectroscopy (IR), and mass spectrometry (MS). 1 exhibited significant inhibitory activity against the human DNA topoisomerase I (hTopo I), the cancer cell lines BEL-7402 and MCG-803, with the IC50 values 12.0, 6.5, and 8.0 y8/mL, respectively. The volatile oil, the fraction of petroleum ether: EtOAc = 20:1 (V/V) on Si gel chromatography, was also quantitatively analyzed by gas chromatography mass spectrometry (GC-MS). As a result, 60 compounds were identified. Among them, the long chain aliphatics, terpenes and steroids, as the representative structure type, were found with percentages of 36.16%, 6.42% and 9.28%, respectively.
  • LIU Xinhua, WANG Shifan, SONG Baoan
    4-(2-Hydroxy-phenyl)-but-3-en-2-one (1) was prepared via condensation of salicylaldehyde with acetone, and then reaction of the ketone 1 with thiosemicarbazide was accompanied by cyclization to give substituted pyrazole (2). Seven new 5-(2-hydroxy-phenyl)-3-methyl-4,5-dihydropyrazole-1-carbothioamide derivatives (3a-3g) were synthesized by the acylation of 2 and characterized by means of elemental analysis, infrared (IR), and 1H nuclear magnetic resonance (NMR). The compounds 3c, 3d, and 3g showed certain bactericidal activity against E. coli; while compound 3g showed certain bactericidal activity against P. vulgaris.
  • LI Jun, ZHANG Jijuan, ZHAO Xinjuan, YU Yan
    Using an emulsification-gelation method, chitosan-sodium alginate-porcine hemoglobin microcapsules were prepared. Results show that these microcapsules have better forms and small granules with 1 ?m size of the mean particle size. They possess a relatively narrow and normal Gaussian distribution. The loading efficiency of porcine hemoglobin (pHb) in microcapsules is more than 90%. The pHb released from microcapsules is extended for more than one month. Chitosan-sodium alginate-hemoglobin micro capsules are expected to become an artificial oxygen-carrying therapeutic agent with sustained release for intravenous injection.
  • HE Yaning, LIU Bin, REN Hongfeng, WANG Xiaogong
    Elastomeric replicas of surface relief structures were prepared by molding poly(dimethylsiloxane) (PDMS) precursors against photo-inscribed surface-relief-gratings on azo polymer films. The PI solutions were micro-contact printed with the elastomeric PDMS replica on quartz slides. Good surface-relief-grating structures were formed on the quartz slides. The quartz slides covered with surface-relief-grating polymide (PI) films were then assembled into liquid crystal (LC) cells. The transmittance passing through the cell between crossed polarizers changed periodically with a regular 90º separation of the rotational angle. The pretilt angle of the cell was found to be 2.8º. Results showed that the PI films with surface-relief-grating structures by this micro-contact printing process have good liquid crystal alignment ability. This preparation method of alignment layers can be considered a potentially useful technique in the LC display (LCD) industry in the future.
  • WU Hui, GUO Huiling, LEI Jiaheng, ZHANG Rongguo, LIU Yong
    The relationship between the structure and performance of polycarboxylate superplasticizer was analyzed. The respective functions of the structure units of the main and branched chains were discussed. The progress of synthesis and molecular structure design and synthesis of polycarboxylate superplasticizer were reviewed according to the difference in the structure unit of the main chain. Results indicated that their performance is related to the structure unit of the main and branched chains, as well as the position and species of functional groups. The polycarboxylate superplasticizer, which had suitable graft and block polymers of polyethylene glycol or polyoxyethylene, and a suitable sulfonic group, had small slump loss besides high water-reducing performance. On the other hand, the hydroxyl group at the end of the chain causes gelation easily. On the basis of the items mentioned above, as well as the source and cost of raw materials, esterification of polyethylene glycol and acrylic acid were first adopted using para-toluene sulfonic acid as catalyst, then polymerized with sodium sulfonate methacrylate. A certain amount of acrylic was added in order to regulate both the polymerization degree of the main chain and the ratio of carboxyl and sulfonic groups in the branched chain. As a result, the high performance superplasticizer has been synthesized (was obtained). The divergence of the cement plasma is about 200 mm when the addition amount of superplasticizer is 0.16%–0.20% of cement weight, and the ratio of the water and cement is 0.29.
  • MA Jie, WU Hai, ZHU Yaqi
    A novel amperometric hydrogen peroxide sensor was proposed by co-immobilizing new methylene blue (NMB) and Horseradish peroxidase (HRP) on glassy carbon electrode through covalent binding. The electrochemical behavior of the sensor was studied extensively in 0.1 mol/L phosphate buffering solution (pH = 7.0). The experiments showed NMB could effectively transfer electrons between hydrogen peroxide and glassy carbon electrode. The electron transfer coefficient and apparent reaction rate constant were determined to be 0.861 and 1.27 s-1. The kinetic characteristics and responses of sensor on H2O2 were investigated. The Michaelis constant is 8.27 mol/L and the linear dependence of current on H2O2 is in the range of 2.5–100 μmol/L. At the same time, the effects of solution pH, buffer capacity, and temperature on the sensor were examined.