Stereoselective Desymmetrization of gem-Diborylalkanes by “Trifluorination”

An efficient and general method for the chemoselective synthesis of unsymmetrical gem-diborylalkanes is reported. This method is based on a late-stage desymmetrization through nucleophilic “trifluorination”, providing chiral gem-diborylalkanes bearing a trifluoroborate group. The reaction offers a highly modular and diastereoselective approach towards the synthesis of gem-diborylcyclopropanes. The utility of the gem-diborylalkane building blocks was demonstrated by selective post-functionalization of the trifluoroborate group. These functionalizations include inter- and intra- Pd-catalyzed Suzuki–Miyaura coupling reactions.     

E‐Aroylethenesulfonylacetic Acid Methyl Ester: Source for Bis Heterocycles

A new class of pyrazolyl/isoxazolyl‐oxazolines and thiazolines was synthesized from simple substrate E‐aroylethenesulfonylacetic acid methyl ester with the aid of the samarium(III) chloride catalyst and 1,3‐dipolar cycloaddition methodology.     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

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.     

Organocatalytic highly enantioselective tandem Michael-Knoevenagel reaction for the synthesis of substituted thiochromanes

Enantioenriched tetrasubstituted thiochromanes have been synthesized using a tandem Michael addition-Knoevenagel reaction between 2-mercaptobenzaldehydes and benzylidenemalonates with a 9-epi-aminoquinine thiourea derivative as the catalyst. Steric and electron effects were found to affect profoundly the enantioselectivity and diastereoselectivity of the reaction.     

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.     

Synthesis and antimicrobial activity of pyrrolyl/pyrazolyl arylaminosulfonylmethyl 1,3,4-oxadiazoles, 1,3,4-thiadiazoles and 1,2,4-triazoles

A new class of pyrrolyl/pyrazolyl arylaminosulfonylmethyl 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, and 1,2,4-triazoles were prepared and tested for antimicrobial activity. Amongst the tested compounds, 5c displayed high antimicrobial activity.     

Simultaneous Determination of Ritonavir and Lopinavir in Human Plasma after Protein Precipitation and LC-MS-MS

A simple, rapid, specific and sensitive method has been developed and validated for simultaneous determination of lopinavir and ritonavir in human plasma. The analytical procedure involves a protein precipitation method using fluoxetine as internal standard Separation was carried out on an Inertsil ODS column using a mobile phase consisting of acetonitrile and 5 mM ammonium acetate buffer. The total run time of analysis was 2.0 min. A linear response function was established for the range of concentrations 50.67–10,008.82 ng mL^?1 for lopinavir and 5.066–1,000.693 ng mL^?1 for ritonavir. The method was successfully applied to an oral bioequivalence study in humans.     

Optimization and validation of a low temperature microwave-assisted extraction method for analysis of polycyclic aromatic hydrocarbons in airborne particulate matter

A low temperature microwave-assisted extraction method (MAE) is reported for the analysis of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter (PM). The main parameters affecting the extraction efficiency (choice of extractants, microwave power, and extraction time) were investigated and optimized. The optimized procedure requires a 20 ml mixture of acetone:n-hexane (1:1) for extraction of PAHs in PM at 150 W of microwave energy (20 min extraction time). Clean-up of MAE extracts was not found to be necessary. The optimized method was validated using two different SRM (1648-urban particulate matter and 1649a, urban dust). The results obtained are in good agreement with certified values. PAHs recoveries for both reference materials were between 79 and 122% with relative standard deviation ranging from 3 to 21%. Detection limits were determined based on blank determination using two kinds of quartz filter substrates (n = 10), which ranged from 0.001 (0.03) ng m⁻³ (pg/μg) for B(k)Ft to 1.119 (37.3) for Naph in ng m⁻³ (pg/μg), respectively. The repeatability and day-to-day reproducibility obtained in this study were in the range of 4-16 and 3-25% for spiked standards and SRM 1649, respectively. The optimized and validated MAE technique was applied to the extraction of PAHs from a set of real world PM samples collected in Singapore. The sum of particulate-bound PAHs in outdoor PM ranged from 1.05 to 3.45 ng m⁻³ while that in indoor PM (cooking emissions) ranged from 27.6 to 75.7 ng m⁻³, respectively.