Synthesis and characterisation of bis(pentafluorophenyl)antimony(V) cations, [(C6F5)2SbL3]

Pentacoordinate complex cations of the general formula [(C₆F₅)₂SbL₃]³⁺ stabilized as solid salts in combination with tetraphenylborate (BPh₄), tetrafluorobroate (BF₄) anions, where L=DMSO, Ph₃AsO, PyO, DMF, α-, β- and γ-picoline have been isolated. The newly formed complexes were characterized by elemental analysis, molar conductance measurements, solid-state IR and and NMR. From these results, a five-fold coordination around antimony was required.     

Complete-active-space self-consistent-field/Amber parameterization of the Lys296–retinal–Glu113 rhodopsin chromophore-counterion system

A special hybrid quantum mechanics/molecular mechanics forcefield is defined, parameterized and validated for studying the photoisomerization path of the retinal chromophore in the rhodopsin protein. It couples a multireference ab initio Hamiltonian (CASSCF and second-order multireference many-body perturbation theory using a CASSCF reference) to describe the chromophore while the rest of the protein is approximated with the Amber forcefield. The frontier has been carefully parameterized in order to reproduce full quantum mechanics torsional energy profiles, for both the ground state and the first excited state. It is also shown that replacing the chromophore counterion with point charges is a valid approximation. This result is interpreted in terms of a cancellation effect for which a possible explanation is given.     

GIAO/DFT evaluation of 13C NMR chemical shifts of selected acetals based on DFT optimized geometries

DFT/B3LYP calculations of the ground-state conformation of eight cyclic and acyclic acetals are presented and compared with experimental data. Results of single-point GIAO/DFT calculations at five different levels of theory show that isotropic shieldings need to be empirically scaled to achieve agreement with experimental chemical shifts. Statistical evaluation of data indicates that the most accurate prediction of 13C chemical shifts is achieved at the MPW1PW91/6-311G** level of theory. An empirical equation describing the relationship between delta values and shielding constants is postulated. This equation has been applied to the non-chair ground-state conformation of the six-membered acetonide and to the conformationally flexible benzodioxonine derivative. The agreement observed between the experimental and predicted chemical shifts shows that calculations at the MPW1PW91/6-311G** level of theory are adequate for addressing questions of conformation.     

消除夹带溶胀的新液膜操作法

消除夹带溶胀的新液膜操作法曹汉瑾，褚莹，何彦涛，吴子生，严忠（东北师范大学化学系长春１３００２４）关键词液膜，油／水乳液，溶胀，夹带，包裹消除液膜操作中的夹带溶胀对液膜的工业化具有重要意义，夹带溶胀分为包裹溶胀和再液化溶胀。前者是乳状液滴上浮时将水相...     

Drying agents for water-free introduction of desorption solvent into a GC after on-line SPE of aqueous samples

Summary A small cartridge containing a drying agent is inserted between a solid phase extraction (SPE) column and a gas chromatograph (GC) to enable the introduction of water-free desorption solvent into the GC in on-line liquid chromatography (LC)-type enrichment of trace-level analytes from water samples. Some characteristics of the drying agents, such as their capacity to retain water and their re-usability after heating, have been tested. Possible interactions of the drying agent with the analytes, e.g., irreversible adsorption or catalyzed degradation, have been checked for a wide range of alkanes, alkylbenzenes chlorobenzenes, chlorophenols and phthalate esters. Using the on-line SPE-GC system with flame ionization detection (FID) and spiked samples containing different levels of the test compounds, the repeatability was shown to be satisfactory (6–17%). For 10 mL samples, the detection limits were lower than 0.1 g/L. The on-line SPE-GC-FID system here presented can be used for the repeated analysis of water samples without exchange of the dyring cartridge. The technique is applied to the analysis of tap water.     

N-TiO2/ZnO复合纳米管阵列的掺杂机理及其光催化活性

以ZnO纳米柱阵列为模板, 采用溶胶-凝胶法制备出TiO2/ZnO和N掺杂TiO2/ZnO的复合纳米管阵列. 扫描电镜(SEM)、X射线光电子能谱(XPS)和紫外-可见漫反射吸收光谱(UV-Vis)的结果表明: 两种阵列的纳米管均为六角形结构, 直径约为100 nm, 壁厚约为20 nm; 在N-TiO2/ZnO复合纳米管阵列中, 掺入的N离子主要是以N-Ox、N-C和N-N的形式化学吸附在纳米管表面, 仅有少量的N离子以取代式掺杂的方式占据TiO2晶格O的位置; 表面N物种形成的表面态能级和取代式掺杂导致带隙的窄化, 增强了纳米管阵列的光吸收效率, 促进了光生载流子的分离. 光催化实验结果表明, N离子的掺杂有利于N-TiO2/ZnO复合纳米管阵列光催化活性的提高.     

Fused silica capillary tube isotachophoresis using a multichannel photodiode array detector

Isotachophoresis carried out in a 0.25 mm i.d. fused-silica capillary tube yielded high resolution, compared with that in a fluorinated ethylene-propylene polymer tube. The use of an ultraviolet-visible multichannel spectrophotometer with photodiode array as detector together with a cross flow cell (volume 0.01 μl) was investigated. The system was successfully applied to the analysis of cationic dyes such as neutral red, bismarck brown, and basic fuchsine.     

Products active on mosquitoes,IV: Synthesis and biological activity of 8-propargyloxy-3,7-dimethyl-2,6-octadienyl/6-octenyl ethers

Summary A series of 8-proparglyoxy-3,7-dimethyl-2,6-octadienyl and 8-propargyloxy-3,7-dimethyl-6-octenyl ethers were prepared from 8-hydroxygeranyl and 8-hydroxycitronellyl ethers, respectively. Almost all compounds showed high toxicity toCulex quinquefaciatus larvae at 1 mgl^–1 dose level.

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Gegen Mücken aktive Produkte, 4. Mitt.: Synthese und biologische Aktivität von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl/6-octenyl-ethern

Zusammenfassung Eine Reihe von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl- und 8-propargyloxy-3,7-dimethyl-6-octenyl-ethern wurden aus 8-Hydroxygeranyl- bzw. 8-Hydroxycitronellyl-ethern hergestellt. Fast alle Verbindungen zeigten hoch Toxizität gegenüber Larven vonCulex quinquefaciatus in einer Dosierung von 1 mgl^–1.

     

A novel separation technique of diastereomeric esters of pyridylethanols by extraction: formal total synthesis of PNU-142721, HIV-1 reverse transcriptase inhibitor

The separation of diastereomeric esters derived from (±)-pyridylethanols and 3β-acetoxyetienic acid were achieved by an extraction technique using diethyl ether and aqueous hydrochloric acid. A formal total synthesis of PNU-142721 was effectively carried out to prepare the chiral, non-racemic synthon 1-furo[2,3-c]pyridin-5-yl-ethanol (1) by means of this technique. The structure optimized using MOPAC calculations on each diastereomer suggested the presence of intramolecular CH/π interaction in only the (S)-isomer of the diastereomers.     

溶剂浓度对PVDF相转换膜大孔结构的影响

提出决定大孔能否发展的初始分相点处溶剂浓度临界点的概念 ,认为初始分相点处较高的溶剂浓度有利于大孔的发展 ,溶剂浓度低于一定的界限后 ,大孔停止发展 ,转为海绵状结构 .实验考察了不同凝胶液组成下制得的PVDF中空膜的结构 ,建立了相应的传质模型 ,模拟不同制膜条件下初生态膜内的组成分布情况 ,根据初始分相点处溶剂浓度临界点的概念 ,预测膜的形态结构 .模拟结果与相应制膜条件下的电镜照片有很好的对应关系 ,证明了上述大孔形成机理的正确性 .