合成钛硅分子筛TS-1的一种新方法

In both conventional method[1] and modified method[2] ,organic Si and Ti alkoxides were used as Si source and Ti source respectively, and only strong organic base was used. So this system may be called as organic synthesis one (see Fig 1 )Thangaraj et al[3] reported that in the organic synthesis system only organic strong base TPAOH can be used.     

以TiCl4为钛源合成钛硅分子筛

Since titanium silicalite-1 (TS-1) was first prepared by Taramasso et al[1] in 1983,the synthesis of TS-1 and its application in partial oxidation have become a hotspot in the zeolite catalytic field.For the traditional synthesis route of TS-1,the key problem is its costly price and severe synthesis conditions,which hamper its industrial application.To avoid using costly alkali-free tetrapropylammonium hydroxide (TPAOH) as a template,Müller et al[2] reported that TS-1 could be synthesized using tetrapropylammonium bromide (TPABr) as a template with ammonia as the base to adjust the basicity of the gel.     

硅基催化结构合成的策略

Two approaches to synthesize silicon-based catalytic structures that aim at capturing the properties and functionalities of natural enzymes are described in this brief review:unit-by-unit synthesis of macromolecular units and templating/imprinting synthesis of nanocages. The unit-by-unit approach mimics the peptide synthesis method,offers atomic control of the structure,but is inefficient in synthesizing large structures such as nanocages. The templating/imprinting method is more suitable for nanocages at the sacrifice of atomic control,and the nanocages obtained are shown to possess properties exhibited by enzyme cavities.     

钛硅沸石中的一种非活性钛物种

Synthesis of the titanium silicalite TS-1 was first reported by Taramasso et al[1]in 1983. TS-1 has received considerable interest during the last decade because of its unique catalytic properties in oxidation reactions involving H2O2 as the oxidant. It is accepted that the extraframework Ti species in TS-1 favor the decomposition of H2O2and should be avoided. But in the present study, it was observed that there was a kind of Ti species inactive in both the oxidation reaction and the decomposition of H2O2.     

Molecular Simulation on Transport Properties of Confined Water

The diffusivity and viscosity of water confined in micropores were studied by molecular dynamics simulations. The effects of pore width and density were analyzed at pore widths from 0.9 to 2.6nm. The diffusivity in micropores is lower than that of the bulk, and it decreases as pore width decreases and as density increases. But the viscosity in micropores is much larger than that of the bulk, and it increases as pore width decreases and as density increases. The diffusivity in channel parallel direction is obviously larger than that in channel perpendicular directions.     

Transformation of Oximes and Alcohols to Carbonyl Compounds Using Amberlite IRA-400 Supported Chromic Acid in the Presence of Zirconium Tetrachloride

A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method. A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method.     

Antitumour Activity of Chitosan Hydrogen Selenites

Selenium is a biologically important element and essential for life1. Selenium deficiency causes severe degenerative disease, such as Kesan cardiomyopathy, and has been implicated in increasing the incidence of human cancer and some chronic ailment as well as ageing. Administration of selenium compounds such as sodium selenite protects animals against carcinogens and markedly reduces the incidence of various neoplasms in human2. Chitosan is one of the most abundant glycans in nature and its…     

An Efficient and Novel Synthesis of Carbamate Esters from the Coupling of Amines, Halides and Carbon Dioxide in the Presence of Basic Resin

Organic carbamates exhibit unique physical, chemical and biological properties, accommodating variety of applications in pharmacology1 (drugs, prodrugs and drug intermediates), agriculture2 (pesticides, insecticides, fungicides, herbicides etc.) and as synthetic intermediates in chemical industry3. Their use as protection of amino groups in peptide synthesis4 and as linkers in combinatorial chemistry5 is also well known. Functionalization of amines as carbamates offers an attractive method for…     

PREPARATION OF POLYETHERSULFONE ULTRAFILTRATION MEMBRANES FOR MILK CONCENTRATION AND EFFECTS OF ADDITIVES ON THEIR MORPHOLOGY AND PERFORMANCE

Polyethersulfone membranes were prepared from quaternary systems containing N,N-dimethylacetamide （DMAc） as solvent, polyvinylpyrrolidone （PVP） as constant additive and acetic acid, acetone and water as variable additives. Phase inversion via immersion precipitation was employed for manufacturing of membranes. The prepared films were immersed in the mixture of pure water and 2-propanol （30/70 vol%） as the non-solvent. Acetic acid caused an increment in the flux at high polymer concentration （16 wt%） and a decline in the flux at low polymer concentrations （10 wt% and 13 wt%）. Acetone and water as the solvent in the casting solution declined the flux at any polymer concentration tested. The morphology and performance of the prepared membranes were investigated by scanning electron microscopy and separation experiments using milk as the feed.     

Anaphthalimide-based fluorescent probe for mercaptocontaining compounds

A polarity-sensitive fluorescent probe MNP was rationally designed and synthesized with naphthalimide as the fluorophore and maleimide as the receptor for thiols. MNP is weakly fluorescent due to the photoinduced electron-transfer(PET) from the fluorophore to the receptor, and it displays evidently solvatochromic UV–vis and fluorescence spectra: the emission shifted from 495 nm in n-hexane to545 nm in phosphate buffer solution. Michael addition reaction between thiols and the maleimide in MNP inhibited the PET process, which led to about eight-fold fluorescence enhancement. In addition,MNP showed highly sensitivity to mercapto-containing proteins and it could detect as low as 20.4 mg/m L of BSA in PBS. MNP has potential in fluorescent imaging of thiols in living cells.     

MoO3/Al2O3催化氧化选择性合成亚砜

采用浸渍法制备了不同负载量的MoO3/Al2O3催化剂,讨论了MoO3,Al2O3和MoO3/Al2O3负载的催化剂作用下,利用H2O2进行硫醚氧化制亚砜的反应.结果显示MoO3/Al2O3催化剂负载量为20%时催化活性最高,原料转化率达100%,且没有副产物生成.将该方法应用到兰索拉唑前体的氧化反应中,收率达到80%.催化剂重复使用6次不失活.     

利用Cs基衍生物作为n型掺杂剂改善蓝色有机发光二极管的效率

利用两种Cs基衍生物碳酸铯(Cs2CO3)和醋酸铯(CH3COOCs)作为n型掺杂剂掺入到一种新型的电子传输材料2,9-二(2-萘基)-4,7-二苯基-1,10-菲啰啉(NBPhen)中来提高有机发光二极管(OLEDs)的效率.实验结果表明:器件的驱动电压明显降低,并且优化后得到的Cs基n型掺杂器件(ITO/β-NPB/CBP:5%(w)N-BDAVBi/NBPhen/NBPhen:Cs2CO3(or CH3COOCs)/Al)呈现出较好的电致发光性能,在14 V时电流密度分别为551.80和527.88 mA·cm-2,对应的亮度分别达到39750和39820 cd·m-2,电流效率在亮度为10000 cd·m-2时分别为14.60 cd·A-1(Cs2CO3掺杂)和14.40 cd·A-1(CH3COOCs掺杂),这些参数明显优于传统器件的发光性能(ITO/β-NPB/CBP:5%(w)N-BDAVBi/NBPhen/Cs2CO3/Al,其在14 V时电流密度为312.39 mA·cm-2,对应的亮度为25190 cd·m-2;电流效率在亮度为10000 cd·m-2时为9.45 cd·A-1.此外,基于有机半导体掺杂原理和器件的能级结构对n型掺杂器件效率提高的原因进行了分析.     

Structures Controlled by Entropy: The Flexibility of Strychnine as Example

To study the flexibility of strychnine, we performed molecular dynamics simulations with orientational tensorial constraints (MDOC). Tensorial constraints are derived from nuclear magnetic resonance (NMR) interaction tensors, for instance, from residual dipolar couplings (RDCs). Used as orientational constraints, they rotate the whole molecule and molecular parts with low rotational barriers. Since the NMR parameters are measured at ambient temperatures, orientational constraints generate conformers that populate the whole landscape of Gibbs free energy. In MDOC, structures are populated that are not only controlled by energy but by the entropy term TΔS of the Gibbs free energy. In the case of strychnine, it is shown that ring conformers are populated, which has not been discussed in former investigations. These conformer populations are not only in accordance with RDCs but fulfill nuclear Overhauser effect (NOE)-derived distance constraints and ³J_HH couplings as well.     

Ionic liquids as additives for separation of benzoic acid and chlorophenoxy acid herbicides by capillary electrophoresis

Ionic liquids (ILs) were tested as additives to phosphate-acetate buffer for the separation of chlorophenoxy and benzoic herbicide acids. The effects of buffer concentration, buffer pH, IL concentration, and concentration of organic solvent were investigated. It was found that in the presence of 40 mM phosphate-acetate containing 10% acetonitrile at pH 4.5, addition of 10 mM 1-butyl-3-methylimidazoium could reverse EOF. The shoulder-merged peaks of two herbicide acids, 2,4-dichlorobenzoic acid and 3,5-dichlorobenzoic acid, were successfully resolved by the addition of IL cation. Apart from these, results showed different IL cations had different influences on the migration behavior of some of the analytes, while IL anions did not lead to obvious difference on the separation.     

Mesomeric betaines constructed of quinolinium cations and carboxylate anions separated by thiophene-ethynyl spacers as fluorescent dipoles

4- and 5-((1-Methylquinolinium-3-yl)ethynyl)thiophene-2-carboxylates were prepared starting from 3-ethynylquinoline which was subjected to a Sonogashira-Hagihara coupling with ethyl 4- and 5-bromothiophenecarboxylates, respectively. Methylation to give the corresponding quinolinium salts, saponification under basic conditions, acidification to give the carboxylic acids, and basification finally yielded the title compounds. Calculations of the frontier orbital profiles confirm the classification of these mesomeric betaines as cross-conjugated systems, as the HOMO is essentially located in the carboxylate group which is connected to the spacer by a nodal position. Fluorescence spectroscopic investigations were performed.     

3D-QSAR和分子对接研究吲哚咔唑类细胞周期蛋白激酶抑制剂的选择性

细胞周期蛋白激酶(cyclin-dependent kinases, CDKs)是近年来治疗肿瘤的重要靶标. 由于大多数激酶ATP结合位点的保守性, CDK选择性激酶抑制剂的开发成为当前的研发难点和热点. 针对吲哚咔唑类CDK抑制剂, 我们采用比较分子力场分析方法(CoMFA)建立了CDK2-QSAR(quantitative structure-activity relationship)和CDK4-QSSR(quantitative structure-selectivity relationship)模型. 所建模型的交叉验证系数q2分别为0.722和0.703; 非交叉验证系数r2分别为0.977和0.946, 表明其具有较好的预测能力. 同时, 用分子对接的方法分析了这类化合物与CDK4同源模建结构的作用模式, 根据这两个模型发现, 吲哚咔唑类化合物的R5和R6位长链取代对CDK4的选择性具有一定的影响, 而且结合其作用模式比较合理地解释了这类抑制剂的选择性原因, 这对CDKs的选择性研究具有一定的指导意义.     

寡糖—8—氨基芘—1,3,6—三磺酸衍生物的毛细管电泳—激光诱？…

利用自组装的毛细管电泳－激光诱导荧光装置,研究了多种寡糖－８－氨基芘－１,３,６－三磺酸（寡糖ＡＰＴＳ）衍生物的分离。考察了电泳介质、浓度及pＨ对寡糖－ＡＰＴＳ 衍生物分离的影响,在酸性和碱性条件下,分别实现了痕量寡糖标准品及葡聚糖水解产物的高效分离。     

Determination of quinocide as impurity in primaquine tablets by capillary zone electrophoresis

A capillary zone electrophoretic method has been developed and validated for the determination of the impurity quinocide (QC) in the antimalarial drug primaquine (PQ). Different buffer additives such as native cyclodextrins and crown ethers were evaluated. Promising results were obtained when either β‐cyclodextrin (β‐CD) or 18‐crown‐6 ether (18C6) were used. Their separation conditions such as type of buffer and its pH, buffer additive concentration, applied voltage capillary temperature and injection time were optimized. The use of 18C6 offers slight advantages over β‐CD such as faster elution times and improved resolution. Nevertheless, migration times of less than 5 min and resolution factors (R_s) in the range of 2–4 were obtained when both additives were used. The method was validated with respect to selectivity, linearity, limits of detection and quantitation, analytical precision (intra‐ and inter‐day variability) and repeatability. Concentrations of 2.12 and 2.71% (w/w) of QC were found in pharmaceutical preparations of PQ from two different manufacturers. A possible mechanism for the successful separation of the isomers is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

寡糖-8-氨基芘-1,3,6-三磺酸衍生物的毛细管电泳-激光诱导荧光分离

利用自组装的毛细管电泳-激光诱导荧光装置,研究了多种寡糖-8-氨基芘-1,3,6-三磺酸(寡糖-APTS)衍生物的分离.考察了电泳介质、浓度及pH对寡糖-APTS衍生物分离的影响,在酸性和碱性条件下,分别实现了痕量寡糖标准品及葡聚糖水解产物的高效分离     

Capacity of Tea Scavenging Singlet Oxygen Studied by Means of 1,3-Diphenylisobenzofuran as Fluorescence Probe

1 Introduction In recent years, the effects of reactive oxygen species(ROS) generated in the course of biological metabolism, such as superoxide(O_2~(-.)), hydrogen peroxide(H_2O_2), hydroxyl radical(HO~.) and singlet oxygen(~1O_2) on the human health have received more attention due to their vital roles in physiological functions. Normally, antioxidant molecules, superoxide dismutase and catalase in biological organism can scavenge excessive free radicals by a series of chemical reactions to keep the cells in a state of redox homeostasis[1].