Two new C-glucofuranosyl isoflavones in puerarin injection

Two new C-glucofuranosyl isoflavones of impurities in puerarin injection were isolated.Their structures were determined to be 8-C-α-glucofuranosyl-7,4'-dihydroxyisoflavone and 8-C-β-glucofuranosyl-7,4'-dihydroxy-isoflavone by chemical and spectral analysis.     

Highly efficient removal of allyloxycarbonyl(Alloc)function provides a practical orthogonal protective strategy for carbohydrates

Highly efficient removal of allyloxycarbonyl(Alloc)group was achieved in the presence of CH3COONH4,Pd[P(C6H5)3]4,and NaBH4 in MeOH-THF,within 5 min in almost quantitative yields(90%,isolated yield)without affecting acetyl,benzoyl,isopropylidene,benzylidene,allyl,benzyl,benzyl carbonate,or azido groups.     

Theoretical studies on QSAR and mechanism of 2‐indolinone derivatives as tubulin inhibitors

The theoretical studies on three‐dimensional quantitative structure activity relationship (3D‐QSAR) and action mechanism of a series of 2‐indolinone derivatives as tubulin inhibitors against human breast cancer cell line MDA‐MB‐231 have been carried out. The established 3D‐QSAR model from the comparative molecular field analysis (CoMFA) shows not only significant statistical quality but also predictive ability, with high correlation coefficient (R² = 0.986) and cross‐validation coefficient (q² = 0.683). In particular, the appropriate binding orientations and conformations of these 2‐indolinone derivatives interacting with tubulin are located by docking study, and it is very interesting to find that the plot of the energy scores of these compounds in DOCK versus the corresponding experimental pIC₅₀ values exhibits a considerable linear correlation. Therefore, the inhibition mechanism that 2‐indolinone derivatives were regarded as tubulin inhibitors can be theoretically confirmed. Based on such an inhibition mechanism along with 3D‐QSAR results, some important factors improving the activities of these compounds were discussed in detail. These factors can be summarized as follows: the H atom adopted as substituent R₁, the substituent R₂ with higher electropositivity and smaller bulk, the substituents R₄–R₆ (on the phenyl ring) with higher electropositivity and larger bulk, and so on. These results can offer useful theoretical references for understanding the action mechanism, designing more potent inhibitors, and predicting their activities prior to synthesis. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Synthesis and Characterization of Novel Stilbene Derivatives with 1,3,4‐Oxadiazole Unit

Four novel stilbene derivatives containing 1,3,4‐oxadiazole unit have been synthesized in four steps with overall yields (27～35%). The synthetic route involved one‐step installation of 2,5‐di‐p‐tolyl‐1,3,4‐oxadiazol via the direct coupling of p‐toluic acid with hydrazine hydrate promoted by PPA , benzylic bromination, conventional phosphonate formation, and Wittig‐Horner olefination.     

Differential reactivity of aromatic diamines during polyimide formation in water

A series of mono and di-imide compounds were synthesized by the reaction of common aromatic diamines with 4,5-dichlorophthalic acid in aqueous solution (at temperature between 160 °C and 200 °C) as a precursor to determining the chemical reactivity changes in these diamines during copolyimide synthesis under the same conditions. The reactivities of the second amino group were shown to reduce dramatically, in number of examples, after substitution had occurred on the first amino group. The effect of these reactivity changes on polymer and copolymer properties was examined by the synthesis of a series of polymers containing two of the diamines with very different reactivity behaviours.The model compounds and polymers were characterized by FTIR, ¹H NMR and where possible by mass spectroscopy. The polymers were also characterized by GPC, Tg and some mechanical properties.     

Hollow fiber supported ionic liquid membrane microextraction for determination of sulfonamides in environmental water samples by high-performance liquid chromatography

By using ionic liquid as membrane liquid and tri-n-octylphosphine oxide (TOPO) as additive, hollow fiber supported liquid phase microextraction (HF-LPME) was developed for the determination of five sulfonamides in environmental water samples by high-performance liquid chromatography with ultraviolet detection The extraction solvent and the parameters affecting the extraction enrichment factor such as the type and amount of carrier, pH and volume ratio of donor phase and acceptor phase, extraction time, salt-out effect and matrix effect were optimized. Under the optimal extraction conditions (organic liquid membrane phase: [C₈MIM][PF₆] with 14% TOPO (w/v); donor phase: 4 mL, pH 4.5 KH₂PO₄ with 2 M Na₂SO₄; acceptor phase: 25 μL, pH 13 NaOH; extraction time: 8 h), low detection limits (0.1–0.4 μg/L, RSD ≤ 5%) and good linear range (1–2000 ng/mL, R² ≥ 0.999) were obtained for all the analytes. The presence of humic acid (0–25 mg/L dissolved organic carbon) and bovine serum albumin (0–100 μg/mL) had no significant effect on the extraction efficiency. Good spike recoveries over the range of 82.2–103.2% were obtained when applying the proposed method on five real environmental water samples. These results indicated that this present method was very sensitive and reliable with good repeatabilities and excellent clean-up in water samples. The proposed method confirmed hollow fiber supported ionic liquid membrane based LPME to be robust to monitoring trace levels of sulfadiazine, sulfamerazine, sulfamethazine, sulfadimethoxine and sulfamethoxazole in aqueous samples.     

重量法制备氮中微量氧气体标准物质

介绍重量法制备氮中微量氧气体标准物质的实验方法和结果.考察了环境空气对微量氧配制过程中引入误差的影响,对称量法制备气体标准物质不确定度进行了评定并对不确定度进行了验证,验证结果吻合在l%之内;氧含量在0～10 μmoL/mol范围内重量法制备的气体标准物质的不确定度小于1%,并且取得了国际的等效性.     

A simple colorimetric sensor for biologically important anions based on intramolecular charge transfer (ICT)

A sensitive colorimetric sensor (1) based on 4,5-dinitrobenzene-1,2-diamine was designed and synthesized. Binding of anions such as AcO⁻, F⁻ and results in a notable change in the visible region of spectrum (an approximately 90 nm red shift), which can be detected by the ‘naked-eye’. Furthermore, the binding ability was evaluated by UV–vis titration experiments as following: AcO⁻ > F⁻ >   Cl⁻, Br⁻, I⁻. The nature of the color change of 1 induced by AcO⁻ was due to the intramolecular charge transfer (ICT) which was confirmed by X-ray crystal structure and ¹H NMR titration spectra.     

Electrochemical Sensor for trans‐Resveratrol Determination Based on Indium Tin Oxide Electrode Modified with Molecularly Imprinted Self‐Assembled Films

A voltammetric sensor for sensitive and specific determination of trans‐resveratrol (RES) were prepared based on immobilization of an RES‐imprinted film on the surface of functionalized Indium Tin Oxide (ITO) electrode, which was modified with γ‐methacyloxypropyl trimethoxysilane (γ‐MPS). Cyclic Voltammetry (CV) was presented to extract RES from the molecularly imprinted polymer film and RES were extracted rapidly and completely. The binding performance of the imprinted electrode with the template RES were investigated using differential pulse voltammetry (DPV). The results showed that the imprinted ITO film can give selective recognition to the template RES over that of structurally analogous molecules. A linear response to RES in the concentration range of 2.0×10^?6 M to 2.0×10^?5 M was observed with a correlation coefficient of 0.992, and the detection limit of the electrochemical sensor was 8.0×10^?7 M. Whereas, binding to the reference nonimprinted electrode, made in the same way but without the addition of template RES, there was almost no response to RES.     

Sensitive detection of potassium ion using Prussian blue nanotube sensor

A model K⁺ sensor using Prussian blue nanotubes is fabricated by electrochemical deposition of Prussian blue (PB) within the nanochannels of a porous metal-coated membrane with partially covered pore openings. The PB nanotube sensor exhibits excellent stability giving reproducible peak potentials up to 500 measurement cycles, a very low detection limit of 2.0 × 10⁻⁸ M and extremely wide logarithmic linear ranges between 5.0 × 10⁻⁸–7.0 × 10⁻⁴ M and 7.0 × 10⁻⁴–1.0 M. Negligible interferences by Na⁺, Mg²⁺ and Ca²⁺ are observed and a rapid analysis time of 30 s is readily achieved. The ease of electrodeposition, high stability of PB nanotubes and outstanding analytical performance which surpasses conventional PB voltammetric and potentiometric sensors demonstrates potential sensing applications including ion sensors and biosensors using PB and other metal hexacyanoferrate nanotubes.