Selective copper-promoted cross-coupling reaction of anilines and alkylboranes

Extension of the Chan–Lam N-alkylation of anilines by using alkylboranes as organoboron partners is reported. Alkylboranes, synthesized by hydroboration of styrenes, are effectively coupled with anilines, which comprises a facile method for the synthesis of highly functionalized phenethylaniline derivatives. This is the first time that alkylboranes are used in C–N copper-promoted cross-coupling reactions.     

Potassium sorbate release from poly(vinyl alcohol)-bacterial cellulose films

Active packaging materials are the subject of research because their performance exceeds that of traditional packaging. From this class, antimicrobial materials extend the shelf-life of products and reduce the risk of contamination by pathogens. In this paper, new composite materials with antimicrobial properties are obtained by using polyvinyl alcohol and bacterial cellulose powder. Potassium (2E,4E)-hexa-2,4-dienoate was used as the antimicrobial agent. The films thus obtained were characterised using Fourier-transform infrared spectroscopy and scanning electron microscopy. Mass transfer phenomena concerning the release of potassium (2E,4E)-hexa-2,4-dienoate were investigated. The results indicated that the new biocomposite films could be used as antimicrobial packaging materials.     

CO2 adsorption by activated templated carbons

Highly porous carbons have been prepared by the chemical activation of two mesoporous carbons obtained by using hexagonal- (SBA-15) and cubic (KIT-6)-ordered mesostructured silica as hard templates. These materials were investigated as sorbents for CO(2) capture. The activation process was carried out with KOH at different temperatures in the 600-800°C range. Textural characterization of these activated carbons shows that they have a dual porosity made up of mesopores derived from the templated carbons and micropores generated during the chemical activation step. As a result of the activation process, there is an increase in the surface area and pore volume from 1020 m(2)g(-1) and 0.91 cm(3)g(-1) for the CMK-8 carbon to a maximum of 2660 m(2)g(-1) and 1.38 cm(3)g(-1) for a sample activated at 800°C (KOH/CMK-8 mass ratio of 4). Irrespective of the type of templated carbon used as precursor or the operational conditions used for the synthesis, the activated samples exhibit similar CO(2) uptake capacities, of around 3.2 mmol CO(2)g(-1) at 25°C. The CO(2) capture capacity seems to depend on the presence of narrow micropores (<1 nm) rather than on the surface area or pore volume of activated carbons. Furthermore, it was found that these porous carbons exhibit a high CO(2) adsorption rate, a good selectivity for CO(2)-N(2) separation and they can be easily regenerated.     

Isolation and characterization of unusual multinuclear Schiff base complexes: rearrangements reactions and octanuclear cluster formation

The isolation and full characterization of multinuclear Schiff base complexes is reported, and their relevance as precursors for octanuclear Zn(8) salen cluster complex formation is discussed. Starting from simple precursors, three tetranuclear Zn(4) complexes were accessed that incorporate typical half-salen units and comprise of bridging acetates. The use of alternative reaction conditions or a step-wise approach smoothly leads to Zn(8) cluster formation. In addition, the tetranuclear Zn(4) complexes themselves may also serve as precursors toward Zn(8) cluster formation when treated under appropriate reaction conditions. The influence of the solvent medium in the latter Zn(4) → Zn(8) conversion was separately studied and revealed the formation of unusual pyridine-ligated multinuclear structures with fully condensed salen coordination pockets, providing a possible prelude to octanuclear cluster formation.     

Study of the chemical mechanism involved in the formation of tungstite in benzyl alcohol by the advanced QEXAFS technique

Insight into the complex chemical mechanism for the formation of tungstite nanoparticles obtained by the reaction of tungsten hexachloride with benzyl alcohol is presented herein. The organic and inorganic species involved in the formation of the nanoparticles were studied by time-dependent gas chromatography and X-ray diffraction as well as by time-resolved in situ X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopy. Principal component analysis revealed two intermediates, which were identified as WCl(4) and WOCl(4) by using linear combination analysis. Quick-scanning extended X-ray absorption fine structure spectroscopy enabled the time-dependent evolution of the starting compound, the intermediates and the product to be monitored over the full reaction period. The reaction starts with fast chlorine substitution and partial reduction during the dissolution of the tungsten hexachloride in benzyl alcohol followed by the generation of intermediates with W=O double bonds and finally the construction of the W-O-W network of the tungstite structure.     

Different morphologies of the dry physical gels as a function of the sample preparation method

Xerogels obtained by drying the gels formed by glucofuranose derivatives with organic solvents were studied. The xerogels were characterized using the SEM, XRD, DSC and OPM techniques. The morphology of a xerogel observed by SEM may change from ‘amorphous, fibrillar’ to ‘crystal-like’, which may be caused by time or temperature. The results suggest that a similar transition may take place when the xerogel is being prepared. Thus SEM pictures of xerogels should be treated with great caution as they may not reflect the gelator network morphology in the bulk gel.     

Infinitesimal Lifting and Jacobi Criterion for Smoothness on Formal Schemes

This a first step to develop a theory of smooth, étale, and unramified morphisms between Noetherian formal schemes. Our main tool is the complete module of differentials, which is, a coherent sheaf whenever the map of formal schemes is of pseudofinite type. Among our results, we show that these infinitesimal properties of a map of usual schemes carry over into the completion with respect to suitable closed subsets. We characterize unramifiedness by the vanishing of the module of differentials. Also we see that a smooth morphism of Noetherian formal schemes is flat and its module of differentials is locally free. The article closes with a version of Zariski's Jacobian criterion.     

Survey of Modified Classical Bifurcations Due to Deformation-Sensitive Loading with Nonlinear,Nonsmooth and Nonconvex Effects

Some loading devices show certain deformation-sensitive but conservative characteristics leading to changes of the classical postbifurcation behavior of structures. To compare the effect of dead and configuration-dependent loading devices, classical bifurcation models are considered. Fully nonlinear behavior is considered, in sense of material, geometry and loading. Originally or approximately nonsmooth functions are included with nonconvexity in the material or loading behaviour. Global equilibrium paths are modified by deformation-sensitive loading devices, nonsmoothness and nonconvexity.     

Modified Baby Milk—Bioelements Composition and Toxic Elements Contamination

Breast milk has the most suitable composition for the proper development in the first year of a child’s life. However, it is often replaced with artificial milk. The aim of the study was to analyze the composition of essential elements: Na, K, Ca, P, Mg, Fe, Zn, Cu, and Mn as well as toxic elements: Ni, Pb, Sr, Li, and In in 18 formulas available in Poland. The daily supply was also estimated. The study was performed by Inductively Coupled Plasma Optical Emission Spectrometry method. The results showed the presence of all essential elements tested, but the content of P and Mn significantly differed from the concentrations declared. Such discrepancies can have significant impact on the daily dose of the bioelements taken. However, the content of elements was within the reference standards established by the EU Directive with exception of P, the amount of which exceeded the norms 5.23–18.80-times. Daily supply of P in tested milk as well as Fe and Mn provided with first and hypoallergenic formula exceeded the adequate intake. Analysis revealed the contamination with harmful elements—Pb, Sr, Li, and In were detected in almost all products. The study confirms the data concerning some discrepancies in composition and the contamination of food and may provide information on the feeding quality of children and estimation of health risk associated with exposure to toxic elements.