Palladium‐Catalyzed Oxidative Cycloisomerization of 2‐Cinnamyl‐1,3‐Dicarbonyls: Synthesis of Functionalized 2‐Benzyl Furans

A new palladium‐catalyzed intramolecular oxidative cycloisomerization of readily available starting materials, 2‐cinnamyl‐1,3‐dicarbonyls, has been demonstrated for the creation of structurally diverse 2‐benzyl furans. The cycloisomerization occurs by a regioselective 5‐exo‐trig pathway. The reaction shows a broad substrate scope with good to excellent yields. Furthermore, a one‐pot procedure has been executed by using readily available cinnamyl alcohols and 1,3‐diketones.     

New Measurements of Internal Conversion Coefficients in $${}^{{111}}$$ Cd

Physics of Atomic Nuclei - The 7.5-day beta decay of $${}^{111}$$ Ag is studied with a 60 cc HPGe gamma spectrometer system and a high transmission Mini-Orange magnetic spectrometer. Precise gamma...     

Nanoscale coatings for control of interfacial bonds and nanotube growth

This paper describes the usefulness of nanoscale coatings in improving some engineering materials having porous and uneven surfaces (microcellular foam, nanofibers, nanotubes, etc.). It is shown that 3-5 nm coatings deposited in microwave plasma can influence crucial properties for a wide variety of applications. Two coatings resulting in opposite chemistries have been studied, an oxide layer that increases surface reactivity_, and a similar fluorocarbon layer that makes it inert. In-depth atomic level microscopic and spectroscopic investigations of nucleation and growth of these layers on various substrates have been reported earlier. The effectiveness of such coatings in modifying bond strength, wettability and catalytic activity of various porous and uneven carbon surfaces have been shown here. The following influences of nanoscale functional coatings have been elaborated upon: (a) modification of carbon-polymer interfaces (b) controlled metallization of carbon (c) influence of nano-coatings on catalytic activity, for formation of carbon nanotubes on larger structures.     

Block copolymer micelles in aqueous media

Polystyrene-block-poly(methacrylic acid) and poly(methacrylic acid)-block-polystyrene-block-poly(methacrylic acid) di- and triblock copolymers form micelles with polystyrene cores and poly(methacrylic acid) shells when dissolved in water/1, 4-dioxane mixtures, rich in dioxane. These micelles can be transferred into water rich mixtures, into water, and into aqueous buffers by stepwise dialysis. Quasielastic light scattering and sedimentation velocity experiments show that in dioxane rich mixtures exists a dynamic micellization equilibrium, while in dioxane poor solutions and in aqueous buffers the equilibrium is frozen. The process of mixed micelles formation was observed in dioxane rich solutions.     

Bmim]PF(6): a novel and recyclable ionic liquid for conversion of oxiranes to thiiranes in aqueous media

A variety of epoxides respond rapidly with potassium thiocyanate in [bmim]PF(6)-H(2)O (2:1) solvent system at room temperature under mild and convenient conditions to produce the corresponding thiiranes in high to quantitative yields. Enhanced rates, improved yields, and recyclability of ionic liquids are the remarkable features observed in ionic liquids (ILs). The use of ionic liquids for this transformation avoids the use of heavy metal halides as promoters and chlorinated hydrocarbons as solvents. The ionic liquid was recycled in five to six subsequent runs with gradual decrease in activity.     

Computational studies on nonlinear optical property of novel Wittig-based Schiff-base ligands and copper(II) complex

Hundred and forty-five novel molecules of Wittig-based Schiff-base (WSB), including copper(II) complex and precursors, were computationally screened for nonlinear optical (NLO) properties. WSB ligands were derived from various categories of amines and aldehydes. Wittig-based precursor aldehydes, (E)-2-hydroxy-5-(4-nitrostyryl)benzaldehyde (f) and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl) benzaldehyde (g) were synthesised and spectroscopically confirmed. Schiff-base ligands and copper(II) complex were designed, optimised and their NLO property was studied using GAUSSIAN09 computer program. For both optimisation and hyperpolarisability (finite-field approach) calculations, Density Functional Theory (DFT)-based B3LYP method was applied with LANL2DZ basis set for metal ion and 6-31G* basis set for C, H, N, O and Cl atoms. This is the first report to present the structure–activity relationship between hyperpolarisability (β) and WSB ligands containing mono imine group. The study reveals that Schiff-base ligands of the category N-2, which are the ones derived from the precursor aldehyde, 2-hydroxy-5-(4nitro-styryl)benzaldehyde and pre-polarised WSB coordinated with Cu(II), encoded as Complex-1 (β = 14.671 × 10^?30 e.s.u) showed higher β values over other categories, N-1 and N-3, i.e. WSB derived from precursor aldehydes, 2-hydroxy-5-styrylbenzaldehyde and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl)benzaldehyde, respectively. For the first time here we report the geometrical isomeric effect on β value.     

Co-dopant affect on the structural,electrical and magnetic properties of zirconium and copper co-substituted Ni0.75Zn0.25Fe2O4 spinel ferrites synthesized by sol-gel method

The zirconium and copper co-substituted Ni_0.75Zn_0.25Zr_xCu_xFe_2-2xO₄ (where x?=?0.05, 0.1, 0.15, 0.2) ferrites have been prepared by sol-gel auto-combustion method. The XRD patterns provide the evidence of single phase cubic spinel structure. The theoretical and experimental lattice parameters have resemblance with increase dopant concentration. The sintered density and porosity show the opposite trend with dopant concentration. The FT-IR spectrum of prepared samples reveal cubic spinel with $Fd\overline{3}m$($O_h^7$) space group. The wave numbers of tetrahedral and octahedral sites show agnate trend. The dielectric constant and loss factors decreased with increasing dopant concentration. The saturation magnetization and net magnetic moment have the identical trend with increasing dopant concentration. The coercive field is decreased with increasing dopant concentration. The Y–K angles are increased with increasing dopant concentration. The Q-factor in prepared samples, exhibit narrower frequency bands with increasing frequency.     

Investigation of growth, coverage and effectiveness of plasma assisted nano-films of fluorocarbon

Plasma-assisted functional films have significant potential in various engineering applications. They can be tailored to impart desired properties by bonding specific molecular groups to the substrate surface. The aim of this investigation was to develop a fundamental understanding of the atomic level growth, coverage and functional effectiveness of plasma nano-films on flat surfaces and to explore their application-potential for complex and uneven shaped nano-materials. In this paper, results on plasma-assisted nano-scale fluorocarbon films, which are known for imparting inertness or hydrophobicity to the surface, will be discussed. The film deposition was studied as a function of time on flat single crystal surfaces of silicon, sapphire and graphite, using microwave plasma. X-ray photoelectron spectroscopy (XPS) was used for detailed study of composition and chemistry of the substrate and coating atoms, at all stages of deposition. Atomic force microscopy (AFM) was performed in parallel to study the coverage and growth morphology of these films at each stage. Combined XPS and AFM results indicated complete coverage of all the substrates at the nanometer scale. It was also shown that these films grew in a layer-by-layer fashion. The nano-films were also applied to complex and uneven shaped nano-structured and porous materials, such as microcellular porous foam and nano fibers. It was seen that these nano-films can be a viable approach for effective surface modification of complex or uneven shaped nano-materials.     

Application of ionic-liquid supported cloud point extraction for the determination of microcystin-leucine-arginine in natural waters

A cloud point extraction method has been developed using an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMiM PF(6)) for the determination of a widely studied cyanotoxin (microcystin leucine-arginine, MCLR) in natural waters. Extraction parameters such as sample pH, extraction temperature, extraction time, the amount of ionic liquid and the amount of extraction volume were investigated and optimized to achieve the maximum extraction efficiency. The results obtained indicated a good linearity with the correlation coefficient of 0.995 over the range of 0.5-50 μg L(-1). The relative standard deviation (RSD) of the method was 7.5% (n=6). The calculated method detection limit was 0.03 μg L(-1) (n=6). The practical applicability of the technique was demonstrated by analyzing water samples (n=9) collected from three different sites in local reservoirs.     

A rapid and sensitive LC-MS/MS method for quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma and its pharmacokinetic application

A rapid and sensitive liquid chromatography–tandem mass spectrometric (LC‐MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6‐o‐desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid–liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n‐hexane. The reconstituted samples were chromatographed on a C₁₈ column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm , pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09–24.2 ng/mL for donepezil and 0.03–8.13 ng/mL for 6‐o‐desmethyl donepezil. The results of the intra‐day and inter‐day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd.