Advanced chiral molecular media for enantioselective electrochemistry and electroanalysis

An increasing number of strategies and tools have been proposed to endow the electrochemical interphase with chirality, to achieve enantiodiscrimination in analytical and/or preparative applications. So far, chirality has mostly been implemented not only at the electrode surface side but also on the medium one. Recently, the attractiveness of the latter approach has remarkably increased on account of the increasing availability of advanced chiral molecular media with intrinsic attractive features for electrochemistry applications, such as chiral ionic liquids, chiral ionic liquid crystals, and chiral deep eutectic solvents. With respect to solid layer/fixed chiral networks, advanced chiral media can still offer a reasonably high degree of local structuring, while being less demanding concerning preparation and management protocols, as well as less sensitive to fouling/regeneration issues. Different ways to implement chirality in advanced molecular media, including cases of powerful ‘inherent chirality,’ will be presented and discussed, particularly focusing on recent applications in the electrochemical field.     

Synthesis and molecular structure of novel 4‐aryloctahydropyrido‐[1,2‐c]pyrimidine derivatives

A series of new 4‐aryloctahydropyrido[1,2‐c]pyrimidine‐1,3‐diones 6a,b,d‐h and j were synthesized by intramolecular cyclization of α‐aryl‐α‐(1‐ethoxycarbonyl‐2‐piperidyl)‐acetamide derivatives 5a,b,d‐h and j . The structures of compounds were determined by ¹H and ¹³C nmr spectroscopy. Nmr and X‐ray diffraction data indicate that the configuration at the C4, C4a stereocenters constitute RR and SS pair.     

Simple synthesis of some unsaturated 1,1-difluoro-2-hydroxyethylphosphonates

A short synthesis of some 1,1-difluoro-2-hydroxymethylphosphonates in good yields is described. This procedure involves the regioselective 1,2-addition of [(diethoxyphosphoryl)difluoromethyl]lithium toward unsaturated aldehydes and ketones.     

Open beauty production in high energy π−-tungsten interactions

We present a study of \(B\bar B\) meson pair production inπ ^? interactions at 140, 194 and 286 GeV incident pion energy. At 286 GeV, where we have the best statistics, we find a model-dependent \(B\bar B\) production cross-section \(\sigma _{BB} = 14_{ - 6}^{ + 7} nb/nucleon\) .     

Enantioselective selectors for chiral electrochemistry and electroanalysis: Stereogenic elements and enantioselection performance

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Meson production inp+U,O+U and S+U interactions at 200 GeV/nucleon

Meson production in proton, oxygen and sulphur interactions with uranium targets at 200 GeV/nucleon is studied. We measure the inclusive meson cross-section d /dP _T ² and its evolution fromp+U to S+U. The cross-section fitted with an exponential gives an inverse slopeP _T0 of the order of 210 MeV/c. As a function of the neutral transverse energy,P _T0 values show a slight rise followed by a plateau. The normalized difference (⁺–^–)/^– between positive and negative meson cross-sections is found to increase withE _T .also at ISEL     

Structure and plasmonic properties of thin PMMA layers with ion‐synthesized Ag nanoparticles

Silver nanoparticles are synthesized in polymethylmethacrylate by 30 keV Ag⁺ ion implantation with high fluences. The implantation is accompanied by structural and compositional evolution of the polymer as well as sputtering. The latter causes towering of the shallow nucleated Ag nanoparticles above the surface. The synthesized nanoparticles can be split into two groups: (i) located at the surface and (ii) fully embedded in the shallow layer. These two groups provide corresponding spectral bands related to localized surface plasmon resonance. The bands demonstrate considerable intensity making the synthesized composites promising for plasmonic applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 664–672     

Electrode and electrodeless impedance measurement for determination of orange juices parameters

Electrical impedance spectroscopy (EIS) is a non-destructive, rapid and real-time measurement method which does not require special high-tech measurement devices and can be applied to food quality assessment. This method is rapid, effective and affords low-cost investigation of the product. The conventional EIS method requires a set of metal electrodes in direct contact with the medium to be measured. The complicated electrochemical processes on the electrodes-electrolyte interface could substantially affect the value of the impedance measured. The present study sought to explore the possibilities of using the impedance method for quality control in orange juices, to introduce the electrodeless method of electrolyte impedance measurement and to compare this with the conventional impedance methods. The electrical properties of the orange juices were described with the help of an equivalent circuit. An equivalent circuit was designed with constant phase element approximation. The values of the equivalent circuit components were fitted using a non-standard algorithm inspired by the behaviour of actual ant colonies. Implementing the electrodeless method obviated the electrodes phenomena effects and the behaviour of the electrolyte is similar to inductance. The proposed electrodeless method is generally applicable to measuring the electrochemical properties of electrolytes.     

Curing kinetics study of melamine–urea–formaldehyde resin

The influence of the preconditioning at different temperatures on the cure kinetics of melamine?Curea?Cformaldehyde resins coated on stone wool was investigated under acidic conditions using differential scanning calorimetry and thermogravimetry. The higher pre-treatment temperature was applied, to which resin-coated stone wool was exposed, the lower was the mass loss during the experiment. Kinetic model parameters were determined in two different manners, with the parameters being independent of preconditioning temperature and dependent on the latter. The apparent orders of reaction were approximately two (all of them being within the range 0.96?C2.33), which would imply that cross-linking predominantly proceeds via the bimolecular reaction of either melamine or urea and formaldehyde. Nonetheless, the apparent orders of reaction decreased as a function of preconditioning temperature. The apparent activation energies varied less with preconditioning temperature, assuming values between 64.2 and 78.5?kJ?mol^?1. The applicability of nth-order reaction kinetic models was consequently validated for two other dynamic thermal regimes.     

Radical polymerization of 1‐alkenes catalyzed by lithium salts of carboranes

Radical polymerization of selected 1‐alkenes, (1‐hexene, 1‐octene and 2‐methyl‐1‐heptene), initiated with classical radical initiators and catalyzed by lithium salts of selected carboranes was studied. In accordance with recently published results it was found that the use of radical initiators under catalysis by “naked” lithium cation of carboranes promotes the radical polymerization of 1‐alkenes, otherwise nonpolymerizable by the radical mechanism. However, although in our experiments relatively high monomers conversions are reached for some of the thermal initiators used, only low‐molecular‐weight oligomers with M_n < 1000 are formed, regardless of the initiator and carborane anion used. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011