Ion transport in polymerized lyotropic liquid crystals containing ionic liquid

In this work, we investigate the effect of morphology and segmental dynamics on ion transport in polymerized lyotropic liquid crystals (polyLLCs) containing 1-butyl-3-methylimidazolium tetrafluoroborate as ionic liquid (IL). We demonstrate that two important factors, which affect ion conduction in polyLLCs, are grain size and chain density at the interface. The polyLLC with large grain size (70 nm) shows significant reduction in ion conductivity (one order of magnitude) compared to its homopolymer/IL mixture. However, the polyLLC with small grain size (20 nm) has little difference in ion conductivity compared to its homopolymer/IL mixture. It is observed that decreasing the chain density enhances the interaction of IL with polymer chains and consequently slows the relaxation of polymer chains. In addition, comparing the dynamics of polymer chains in mixtures of homopolymer/IL and templated LLC mesophases shows that the confinement in LLC structure prolongs the relaxation of polymer chains.     

Ab Initio Study of Structures,Metallotropic 1,2-Shifts and Prototropic 1,2-Shifts of Cyclopentadienyl(trimethyl)silane, -germane and -stannane

Molecular structures, metallotropic and prototropic shifts of cyclopentadienyl(trimethyl)silane ( 1 ), cyclopentadienyl(trimethyl)germane ( 2 ), and cyclopentadienyl(trimethyl)stannane ( 3 ) were investigated using ab initio molecular orbital and the Becke, Lee, Yang, and Parr density functional (B3LYP) methods. The results show that the most stable structure of compounds 1-3 has the (CH 3 ) 3 M fragment in the allylic position. The energy barrier of metallotropic shifts in compound 1 is higher than in 2 , and in compound 2 higher than in 3 , in good agreement with experimental data. The cyclopentadienyl rings in compounds 1-3 are found to be planar but this result contradicts the reported experimental data.     

Facile Catalyzed Preparation of 14‐Aryl‐ or Alkyl‐14‐H‐dibenzo[a,j]xanthenes by Dodecylphosphonic Acid and Dodecylsulfamic Acid: Environmentally Benign Methods

Under mild‐ and solvent‐free conditions, one‐pot preparation of 14‐alkyl‐ or 14‐aryl‐14‐H‐dibenzo[a,j]xanthenes could proceed in the presence of catalytic amounts of dodecylphosphonic acid (DPA) and dodecylsulfamic acid (DSA) in good to excellent yields. In these reactions, DPA and DSA are recovered by straightforward work‐ups.     

Development of a graphite low‐temperature plasma source with dual‐mode in‐source fragmentation for ambient mass spectrometry

A new low‐temperature plasma (LTP), based on dielectric barrier discharge (DBD), has been developed as an alternative ionization source for ambient mass spectrometry. For organic samples, the source is able to produce two different fragmentation patterns which are selectable by an electrical switch. The two source modes are different only in the second electrodes: in configuration (A), bar‐plate and in configuration (B), coaxial bar–cylinder shapes are used. A disposable graphite probe is used as the first electrode, the same in both configurations, and a copper foil is used as the second electrode. The ionization source is applicable to gas and liquid samples, without any change being necessary in its design. Under optimal conditions, to take ethylbenzene as an example, a detection limit of less than 25 ng was obtained and a relative standard deviation (RSD) of 13.36% has been demonstrated for 50 ng of ethylbenzene (n = 11). We have found several interesting differences in the mass spectra of the tested volatile organic compounds (VOCs) in the two modes, which might be applicable in identification studies. We have investigated the effect of variation of the first electrode material and the second electrode length in mode B. Moreover, in this design the graphite electrode is capable of acting as a sample adsorbent, which is a new sampling method for LTP mass spectrometry (MS). This capability was investigated by adsorption of the selected VOCs onto the surface of the graphite electrode in a headspace solid‐phase microextraction (SPME) system, and direct desorption and ionization of the samples by LTPMS. Copyright © 2010 John Wiley & Sons, Ltd.     

Fabrication and characterization of copper nanoparticles using thermal reduction: The effect of nonionic surfactants on size and yield of nanoparticles

Thermal reduction has been applied to the preparation of copper nanoparticles (Cu-NPs) using three kinds of nonionic surfactants (Triton X-100, Tween-80, and dodecylamine). The Cu-NPs were formed by decomposition of copper(II) oxalate in presence of triphenylphosphine. The effect of the surfactants on the formation of the Cu-NPs was studied via X-ray diffraction, scanning electron microscopy, energy dispersive analysis of X-rays, transmission electron microscopy, thermogravimetric differential thermal analyses, and Fourier transform infra-red spectroscopy. It is shown that the Cu-NPs have an fcc crystal structure. Depending on the surfactant used, Cu-NPs with diameters between 8 and 20 nm can be prepared. The smallest Cu-NPs (8 nm) were formed in the presence of micelles of dodecylamine (yield 49%), while the largest particles (20 nm) were obtained with Triton X-100 (yield 99%). The use of Triton X-100 results in the highest yield and most uniform Cu-NPs.     

Application of microcrystalline cellulose as an efficient and cheap sorbent for the extraction of metoprolol from plasma and wastewater before HPLC–MS/MS determination

A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography–tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1–1,000 and 0.1–1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method.