Mass spectral studies of N,N-dialkylaminoethanols

Some dialkylaminoethanols, precursors of chemical warfare agents such as V-agents and nitrogen mustards, were analyzed by electron impact (EI) and electrospray ionization (ESI) mass spectrometry. The fragmentation pathways in EI and ESI-MS/MS methods are rationalized. The collision-induced dissociation (CID) spectra of [M+H](+) ions of aminoethanols in ESI mode are clearly distinguishable from one another, including those of isomeric normal and branched chain dialkylaminoethanols. Structures can be proposed based on the general fragmentation pathways of these molecules.     

Surface tension driven self-assembly of bundles and networks of 200 nm diameter rods using a polymerizable adhesive

This letter demonstrates the first utilization of surface tension based self-assembly on the 200 nm scale to form mechanically stable aggregates comprised of metallic rods. The self-assembly occurs as a result of the minimization of interfacial tension of liquid layers of a hydrophobic polymerizable adhesive that is precipitated on the rods. After the assembly, the adhesive is polymerized to form permanently bonded aggregates. Depending on the patterning of the rods and the chemical functionalization used, either closed 3D bundles or open 2D networks can be formed.     

A new and facile route for the synthesis of chiral 1,2-diamines and 2,3-diamino acids

The synthesis of chiral diamines and diamino acids has been achieved from the corresponding N-arylsulfonyl aziridines through reaction with a chiral isocyanate and subsequent hydrolysis of 2-imidazolidinones. The method appears to be general and of wide applicability.     

Adsorption of oleic acid at sillimanite/water interface

The interaction of oleic acid at sillimanite-water interface was studied by adsorption, FT-IR, and zeta potential measurements. The isoelectric point (IEP) of sillimanite obtained at pH 8.0 was found to shift in the presence of oleic acid. This shift in IEP was attributed to chemisorption of oleic acid on sillimanite. Adsorption experiments were conducted at pH 8.0, where the sillimanite surface is neutral. The adsorption isotherm exhibited a plateau around 5 micromol/m2 that correspond to a monolayer formation. Adsorption of oleic acid on sillimanite, alumina, and aluminum hydroxide was studied by FT-IR. Chemisorption of oleic acid on the above substrates was confirmed by FT-IR studies. Hydroxylation of mineral surface was found to be essential for the adsorption of oleic acid molecules. These surface hydroxyl sites were observed to facilitate deprotonation of oleic acid and its subsequent adsorption. Thus protons from oleic acid react with surface hydroxyl groups and form water molecules. Based on the experimental results, the mechanism of oleic acid adsorption on mineral substrate was proposed. Free energy of adsorption was estimated using the Stern-Graham equation for a sillimanite-oleate system.     

Surfactant-free synthesis and functionalization of gold nanoparticles

A new, facile and generally applicable synthesis of functionalized gold nanoparticles is presented. It is based on the surfactant-free generation of weakly stabilized nanoparticles by the reduction of HAuCl4 with sodium naphthalenide in diglyme. These nanoparticles were found to lack long-term stability. However, stabilization in both unpolar and polar solvents could straightforwardly be achieved by subsequent addition of various capping ligands. The resulting ligand-capped gold nanoparticles were investigated by TEM microscopy, UV-vis, and FT-IR spectroscopy. Particle core size can be tuned by the amount of reduction agent. The strict separation of the reduction step and the functionalization step in this one-pot synthesis offers an easy and fast access to highly functionalized gold nanoparticles.     

Pervaporation separation of water + isopropanol mixtures using novel nanocomposite membranes of poly(vinyl alcohol) and polyaniline

Novel nanocomposite polymeric membranes containing nanosized (30–100 nm) polyaniline (PANI) particles dispersed in poly(vinyl alcohol) (PVA) were prepared and used in the pervaporation separation of water–isopropanol feed mixtures ranging from 10 to 50 mass% of water at 30 °C. Of the three nanocomposite membranes prepared, the membrane containing 40:60 surface atomic concentration ratio of PANI:PVA produced the highest selectivity of 564 compared to a value of 77 observed for the plain PVA membrane. Flux of the nanocomposite membranes was lower than those observed for the plain PVA membrane, but selectivity improved considerably. Membranes were characterized by differential scanning calorimetry, dynamic mechanical thermal analyzer, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The highest selectivity with the lowest flux was observed for 10 mass% water containing feed mixture. Flux increased with increasing amount of water in the feed, but selectivity decreased considerably. These results were attributed to the acid-doped PANI particles in the PVA membrane as a result of change in the micromorphology of the nanocomposite membranes. In addition, molar mass between cross-links and fractional free volume of the membranes are responsible for the varying membrane performance. Temperature effect on permeability was investigated for 10 mass% water containing feed with the membrane containing higher concentration of PANI particles, the presence of which could be responsible for varied effect of water permeation through the membrane. Membranes of this study could remove as much as 98% of water from the feed.     

Chelating properties of alpha-oximinocarboxamides--II syn-alpha-oximinophenylacetamide: copper(II) complexes

Syn-alpha-oximinophenylacetamide forms two complexes with Cu(II), a CuL complex at pH < 8.4 and CuL(2) at pH > 8.4. log K(1) = 7.82 +/- 0.07 log beta(2) = 14.32 +/- 0.06.     

An efficient one-pot synthesis of substituted 2-arylbenzo[b]thiophene derivatives

This communication describes an efficient one-pot procedure for the synthesis of 2-arylbenzo[b]thiophene derivatives via reaction of o-halo or nitro aryl carbonyl compounds with benzyl mercaptans in the presence of an excess of anhydrous K₂CO₃ at elevated temperature.     

Coumarin-derived azolyl ethanols: synthesis,antimicrobial evaluation and preliminary action mechanism

A series of coumarin-derived azolyl ethanols including imidazolyl,triazolyl,tetrazolyl,benzotriazolyl,thiol-imidazolyl and thiol-triazolyl ones were conveniently synthesized and characterized by IR,~1H NMR,~(13)C NMR and high-resolution mass spectra(HRMS) spectra.Some of the prepared compounds showed appropriate logP_(ow) values and effective antibacterial and antifungal activities.Noticeably,compound 14 with bis-triazolyl ethanol group exhibited low minimal inhibitory concentration(MIC)value of 8 μg/mL against MRSA,which was comparable or even superior to reference drugs Norfloxacin(MIC=8μg/mL)and Chloramphenicol(MIC=16μg/mL).It could also effectively inhibit the growth of the tested fungal strains compared to Fluconazole.Further binding studies of coumarin 14 with calf thymus DNA were investigated by UV-Vis absorption and fluorescence spectroscopy.It was found that compound 14 could interact with calf thymus DNA by groove binding to form14-DNA complex via both hydrogen bonds and van der Waals force,which might be the factor to exert the powerful antimicrobial activity.     

Autocatalytic oxidation of β‐alanine by peroxomonosulfate in the presence of copper(II) ion

Kinetics and mechanism of oxidation of β‐alanine by peroxomonosulfate (PMS) in the presence of Cu(II) ion at pH 4.2 (acetic acid/sodium acetate) has been studied. Autocatalysis was observed only in the presence of copper(II) ion, and this was explained due to the formation of hydroperoxide intermediate. The rate constant for the catalyzed (k) and uncatalyzed (k) reaction has been calculated. The kinetic data obtained reveal that both the reactions are first order with respect to [PMS]. k values initially increase with the increase in [β‐alanine] and reach a limiting value, but k values decrease with the increase in [β‐alanine]. k values increase linearly with the increase in [Cu(II)], whereas k values increase with [Cu(II)]². Furthermore, k values are independent of [acetate], but k values decrease with the increase in acetate. A suitable mechanism has been proposed to explain the experimental observation. The reaction has been studied at different temperatures, and the activation parameters are calculated. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: 44–49, 2008