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Synthesis, charge-separated state characterization of N-methyl-2-(4'- N-ethylcarbozole)-3-fulleropyrrolidine and its derivatives
Wang Tingting, Wang Tingting, Zeng Heping, Zeng Heping
Front. Chem. China. 2006, 1 (2): 161-169.
https://doi.org/10.1007/s11458-006-0021-1
N-Methyl-2-(N-ethylcarbozole)- fulleropyrrolidine and N-methyl-2- (4'-N,N- diphenylaminophenyl)- fulleropyrrolidine were synthesized by 1,3-dipolar cycloaddition under microwave irradiation, which were characterized by MS, 1H NMR, IR and UV-Vis. Photoinduced intramolecular electron transfer process from C60 moiety to carbazole moiety has been studied by nanosecond laser flash photolysis. The charge-separated state C60°--Cz°+ was observed in the near-IR region with a lifetime of 0.28 μs. The electronic spectrum of the C60-TPA was studied by using ZINDO method on the basis of the optimized geometrics with B3LYP/6-31G* program. The results show that the calculated absorption was beyond 440nm, essentially consistent with the experimental value 433 nm.
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Study on the interaction of aminoglycoside antibiotics with titan yellow by spectrophotometric method and their analytical applications
Wang Mingxia, Liu Zhongfang, Hu Xiaoli, Liu Shaopu, Kong Ling
Front. Chem. China. 2006, 1 (2): 170-173.
https://doi.org/10.1007/s11458-006-0020-2
In a weak acidic medium, the reaction of some aminoglycoside antibiotics (AGs) such as kanamycin sulfate (KANA), gentamycin sulfate (GEN), and tobramycin sulfate (TOB) with acid thiazolyl bisazo dye Titan Yellow (TY) can result in the fading of TY. The maximum fading wavelength was located at 409 nm. The molar absorptivities (?/?104 l mol-1 cm-1) were 2.0, 1.5 and 2.5 for KANA, GEN and TOB, respectively. The spectral characteristics, effect factors, optimum conditions of the reaction and the influence of foreign substances were also investigated. The procedure is easy and fast. This method has high sensitivity and can be applied to the determination of commercial aminoglycoside antibiotics and serum samples with satisfactory results.
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Preparation of mordenite composite membranes with seeding
Su Xiaohui, Li Gang, Lin Ruisen, Kikuchi Eiichi, Matsukata Masahiko
Front. Chem. China. 2006, 1 (2): 179-182.
https://doi.org/10.1007/s11458-006-0018-9
Mordenite composite membranes were prepared by means of coating a porous ?-alumina support with nanosized mordenite seeds followed by hydrothermal crystallization. A systematic investigation was performed on the influence of several factors such as ageing of the reaction mixture, alkalinity, salt addition and temperature on the formation of a mordenite membrane on the seeded support. The ageing of the reaction mixture reduces the growth rate of mordenite crystal along a-axis and b-axis but hardly influences the growth rate along c-axis. As a result, the boundaries between the surface crystals become a little larger with prolonging the period of ageing time. The growth rate of the mordenite crystal along individual axes increases first and then decreases with increasing concentration of sodium hydroxide. A higher alkalinity is unfavorable for the formation of a continuous mordenite membrane. The addition of salt in the reaction mixture has different effect on the growth rate of the mordenite crystal along each axis. With increasing the amount of salt, there was hardly influence on the growth rate along c-axis, whereas an obvious decline was observed in the growth rate along either a-axis or b-axis, which enlarges the boundaries between the surface crystals. The growth rate of the mordenite crystal increases more along c-axis than that along a-axis or b-axis with increasing temperature for hydrothermal crystallization. The use of a temperature as high as 473 K produces a membrane composed of bar-like crystals with larger boundaries.
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Quantitative analysis of complex casein hydrolysates based on chromatography and membrane
Qi Wei, Yu Yanjun, He Zhimin
Front. Chem. China. 2006, 1 (2): 199-202.
https://doi.org/10.1007/s11458-006-0016-y
The enzymatic hydrolysates of casein are so complex that there is no effective method to do quantitative analysis. The common techniques, such as high performance chromatography and SDS-PAGE, can only carry out qualitative analysis. On the basis of membrane separation and high performance size exclusion chromatography (HPSEC), standard peptides with different molecular mass range were prepared, and the linear relationships between mass concentration of the standard peptides and the ultraviolet absorption of corresponding peak areas were established. Consequently, mass concentration of the different hydrolysates at different reaction times could be accurately calculated. The combination of chromatography and membrane separation is of great importance to the quantitative analysis of the complex hydrolysates, which can also be applied to the other macromolecular systems, such as carbohydrates.
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Preparation, characterization and properties studies of quinine-imprinted polymer in the aqueous phase
He Jianfeng, Liu Lan, Yang Guilan, Deng Qinying
Front. Chem. China. 2006, 1 (2): 211-216.
https://doi.org/10.1007/s11458-006-0011-3
The uniform-sized spherical molecularly imprinted polymers were successfully prepared through molecular imprinting technology by two-step seed swelling and mini-emulsion polymerization in the aqueous condition using quinine as template molecules and methacrylic acid (MAA) as functional monomer. The polymers were characterized by IR spectra, thermal-weight analysis, scanning electron microscope and laser particle size analysis. The properties of imprinted polymers were investigated in different organic phases and aqueous media. In the organic media, results suggested that polar interactions (hydrogen bonding, ionic interactions) between acidic monomer/polymer and template molecules are mainly responsible for the binding and recognition; whereas in the aqueous medium, a considerable recognition effect was also obtained where the ionic (electrostatic) interaction and hydrophobic interaction play an important role. The experiments of binding different substrates indicated that the MIPs possessed an excellent rebinding ability and inherent selectivity to quinine.
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Study on characteristics of bias caused by FI–CE split flow electrokinetic injection
Luo Jinwen, Li Huilin, Zhu Hailin
Front. Chem. China. 2006, 1 (2): 217-222.
https://doi.org/10.1007/s11458-006-0013-1
The characteristics of bias caused by split-flow electrokinetic injection (SEKI), a new type of sample injection method used in coupled flow injection capillary electrophoresis system (FI CE), was investigated using pseudoephedrine hydrochloride, a basic drug, and ibuprofen, an acidic drug, as model analytes. It was found that bias imposed by SEKI under the condition of continuous sample matrix/running buffer was similar to that done by electrokinetic injection (EKI). The linearity of calibration curve provided by SEKI was similar to that offered by non-bias hydrodynamic injection (HDI) but significantly better than that obtained by EKI. These features were exploited to improve analytical performances in simultaneous determination of the minor ingredient of pseudoephedrine hydrochloride and the major ingredient of ibuprofen in a pharmaceutical preparation. Detectability of 0.7 mg/l for pseudoephedrine hydrochloride was achieved at a sample throughput rate of 24 times per hour, which is 30% lower than that obtained by HDI-based conventional CE. Relative standard deviations (RSDs) of 2.8% for the minor ingredient and 1.2% for the major ingredient were produced in 11 runs of a test solution containing 13.1 mg/l pseudoephedrine hydrochloride and 81.4 mg/l ibuprofen. This is an improvement compared to that obtained by HDI-based conventional CE. Analytical results for two batches of compound ibuprofen tablets by the SEKI-based FI CE approach were in good agreement with that obtained by a conventional high performance liquid chromatographic method.
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Inhibitory effects of curcumin derivatives on nonenzymatic glucosylation in vitro
Li Manmei, Liu Zhong, Zhang Zhulin, Ma Lin
Front. Chem. China. 2006, 1 (2): 227-231.
https://doi.org/10.1007/s11458-006-0012-2
In this paper, curcumin, demethoxycurcumin, bisdemethoxycurcumin and another curcumin derivative are investigated for their inhibitory effects on nonenzymatic glucosylation in vitro, their binding reaction with bovine serum albumin (BSA) and their influence on the conformational changes of BSA. It demonstrated that all of these curcumin derivatives inhibited the formation of advanced glycation end products (AGE). Curcumin showed the most potent inhibitory activity, followed by demethoxycurcumin and bisdemethoxycurcumin. Moreover, it indicated that they extensively binded to the protein and induced the conformational changes of BSA.
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21 articles
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