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931.
A new metallomicellar system containing cerium(III), a macrocylic polyamine ligand, and the nonionic surfactant Brij35(polyoxyethylene(23) lauryl ether) was prepared and used as a catalyst in the hydrolysis of bis(4-nitrophenyl) phosphate (BNPP). Catalytic rate of the BNPP hydrolysis was measured kinetically using the UV-VIS spectrophotometric method. The results indicate that the metallomicellar system has relatively high stability and excellent catalytic function in the BNPP hydrolysis; also, the reaction rate of the BNPP catalytic hydrolysis increased by a factor of ca. 1 × 1010 compared to the BNPP spontaneous hydrolysis due to the catalytic effect of the active species and the local concentration effect of the micelles in the metallomicellar system. Experimental results also showed that the mono-hydroxy complex containing the macrocyclic polyamine ligand and cerium(III) is the real active species in the BNPP catalytic hydrolysis, and that the micelles provide a useful catalytic environment for the reaction. On basis of the research results, the reaction mechanism of BNPP catalytic hydrolysis has been proposed. 相似文献
932.
Lijun Zhang Qun He Yin Jiang Xun Hu Aimin Yu 《International journal of environmental analytical chemistry》2013,93(11):1250-1261
A new ionic liquid modified silica gel sorbent was prepared from the reaction of active silica gel with N-3-(-3-triethoxysilylepropyl)-3-methylimidazolium chloride ([(TESP)MIm]Cl). This sorbent was exploited as solid phase extractant for separation and preconcentration of metal ions prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). It was found that it can selectively adsorb Fe(Ш). Identification of the surface modification was performed on the basis of FT-IR. Experimental conditions for effective adsorption of trace Fe(Ш) were optimised using both batch and column procedures. At pH 3, Fe(Ш) could be quantitatively adsorbed and completely eluted by using 2?mL of 0.1?mol?L?1 of HCl. 150?mL of sample solution was adopted as the maximum sample volume and a high enrichment factor of 75 was obtained. Most common coexisting ions did not interfere with the separation and preconcentration of Fe(Ш) at optimal conditions. The maximum static adsorption capacity of the sorbent was 37.0?mg?g?1. The detection limit of the present method was 0.48?µg?L?1, and the relative standard deviation (R. S. D.) was lower than 1.7%. The method was successfully applied to the preconcentration of trace Fe(Ш) in biological and natural water samples with satisfactory results. 相似文献
933.
Kongkai Zhu Junyan Lu Zhongjie Liang Xiangqian Kong Fei Ye Lu Jin Heji Geng Yong Chen Mingyue Zheng Hualiang Jiang Jun-Qian Li Cheng Luo 《Journal of computer-aided molecular design》2013,27(3):247-256
New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C–N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies. 相似文献
934.
935.
Jian‐Nan Xiang Li‐Hui Jiang Chao‐Yue Chen Zhi‐ying Fu Jun‐Fei Duan Xiao‐Xiao He 《Journal of carbohydrate chemistry》2013,32(7):595-614
New retinoyl sugar derivatives of 13‐cis‐retinoic acid were synthesized in three ways in this paper in order to enhance pharmacal effects, especially antiproliferative activities of 13‐cis‐retinoic acid. Their structures were confirmed by IR, 1H‐NMR, 13C‐NMR, and MS spectra and their antiproliferative activities were determined in vitro using human cancer lines. Results showed that some compounds possessed potential antitumor activities. 相似文献
936.
Wei-Bin Huang Cai-Yan Du Jian-An Jiang Ya-Fei Ji 《Research on Chemical Intermediates》2013,39(6):2849-2856
A method for concurrent synthesis of vanillin and isovanillin has been developed by a nonregioselective Vilsmeier–Haack reaction of O-alkyl guaiacols. O-Alkylation of guaiacol provided the corresponding O-alkyl guaiacol (1), which was then formylated with N-methylformanilide/phosphorus oxychloride to give a mixture of 4-alkoxy-3-methoxy-benzaldehyde (2) and 3-alkoxy-4-methoxybenzaldehyde (3). Finally, the obtained mixture underwent a selective dealkylation by anhydrous aluminium trichloride, while leaving methyl groups intact to simultaneously achieve the significant fine chemicals vanillin and isovanillin. 相似文献
937.
Yuan Zhu F. Y. Jiang Kexin Chen Feiyu Kang Z. K. Tang 《Journal of Sol-Gel Science and Technology》2013,66(1):180-186
Iron oxide/silica core–shell colloidal particles were prepared by basic reverse microemulsion (RM) method and two modified RM methods. By basic RM method, maximum particle size obtained was mere 40 nm. For building photonic crystals working in the visible range, the colloidal particles must be larger than 100 nm. Thus two modified RM methods were used. By alcohol modified RM method, short chain alcohols were used as co-surfactant. The particle size rose to near 100 nm, but the core–shell structure was comparatively poor. By emulsifier pair modified RM method, the particle size leapt to over 200 nm and a narrow growth window was found favorable to enhance the stability and rigidity of the surfactants layers. The core–shell mechanism was also discussed and a new four-step mechanism was proposed. 相似文献
938.
Li Zhang Li Tong Zhang Jing He Zhi Jun Lin Yan Jiang Li Fu Chen 《Journal of Sol-Gel Science and Technology》2013,68(1):150-154
Aluminum nitride (AlN) fibers were prepared from alumina gel fibers and by heat-treatment in ammonia. The influence of silica on the formation of AlN was investigated. It was shown that phase transformation of alumina (γ-Al2O3 to α-Al2O3) and nitridation reaction took place above 1,100 °C for pure alumina fiber. The addition of a small amount of silica (3 wt%) suppressed the formation of α-Al2O3 and preserved the highly reactive metastable alumina, and nitridation rate was enhanced. Fine grain (~20 nm) AlN fibers were obtained for pyrolysis at 1,150–1,250 °C for 3 h in ammonia, and AlN was identified as the sole crystalline phase. 相似文献
939.
Qumei Jin Fengyu Qu Jingjie Jiang Yan Dong Wei Guo Huiming Lin 《Journal of Sol-Gel Science and Technology》2013,66(3):466-471
A novel dual-drug delivery system based on mesoporous-macroporous silica/polyelectrolytes-SBA-15 has been synthesized. The structure and composition of these materials were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and N2 adsorption–desorption measurements. In this system, water-soluble metformin hydrochloride and fat-soluble ibuprofen were used as model drugs to study the controlled release behavior. The pH-controlled release of individual drugs was obtained by the primary release of metformin hydrochloride from polyelectrolytes-SBA-15 in acid condition and the predominant release of ibuprofen from MMC in alkaline environment. The results show that the polyelectrolytes-SBA-15/mesoporous-macroporous silica can be used as dual-drug release system and the individual drug can be controlled release with the change of pH value of the environment. 相似文献
940.
Jipan Yu Dr. Haijun Yang Prof. Dr. Yuyang Jiang Prof. Dr. Hua Fu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(13):4271-4277
Efficient copper‐catalyzed aerobic oxidative C? H and C? C functionalization of 1‐[2‐(arylamino)aryl]ethanones leading to acridones has been developed. The procedure involves cleavage of aromatic C? H and acetyl C? C bonds with intramolecular formation of a diarylketone bond. The protocol uses inexpensive Cu(O2CCF3)2 as catalyst, pyridine as additive, and economical and environmentally friendly oxygen as the oxidant, and the corresponding acridones with various functional groups were obtained in moderate to good yields. 相似文献