Metal complexes of C2-symmetric chiral bipyridine ligands. X-ray structure of [bis(nitrato)(4S,5S)-2,2-dimethyl-4,5-bis(2-pyridyl)-1,3-dioxolane cobalt(II)]

Chelating properties of C₂-symmetric chiral bipyridine ligands are discussed. In particular we report the syntheses of the cobalt(II), nickel(II), zinc(II) and copper(II) complexes of (4S,5S)-2,2-dimethyl-4,5-bis(2-pyridyl)-1,3-dioxolane. All compounds have been characterized by IR spectroscopy, and an X-ray diffraction analysis has been carried out on one of them: Co(L)(NO₃)₂. The ligand coordinates the cobalt atom by the two nitrogen donors N(1) and N(2). A seven-membered chelation ring is formed, presenting a remarkable non-crystallographic twofold pseudosymmetry around the axis connecting Co and the midpoint of the C(6)–C(7) bond. The metal also binds two monodentate nitrates, thus completing a distorted coordination tetrahedron.     

On continuation of inviscid vortex patches

This investigation concerns solutions of the steady-state Euler equations in two dimensions featuring finite area regions with constant vorticity embedded in a potential flow. Using elementary methods of the functional analysis we derive precise conditions under which such solutions can be uniquely continued with respect to their parameters, valid also in the presence of the Kutta condition concerning a fixed separation point. Our approach is based on the Implicit Function Theorem and perturbation equations derived using shape-differentiation methods. These theoretical results are illustrated with careful numerical computations carried out using the Steklov–Poincaré method which show the existence of a global manifold of solutions connecting the point vortex and the Prandtl–Batchelor solution, each of which satisfies the Kutta condition.     

New experimental and simulated results on nuclear media effects in meson photoproduction off nuclei

New experimental approach to study meson photoproduction in nuclei is discussed. It is based on the measurement of the recoil nucleon as a tagger for identification of the initial step of reaction. Propagation of mesons and nucleons within a nucleus is described by the Intra-Nuclear Cascade (INC) model. Simulations and preliminary experimental data for the deuteron target obtained at GRAAL are presented.     

Pronounced ionic liquid effect in the synthesis of biologically active isatin-3-oxime derivatives under acid catalysis

An efficient method was developed for the preparation of isatin-3-oxime derivatives with Bronsted and/or Lewis acids in imidazolium-based ionic liquids. Isatin-3-oxime bearing the electron donating methoxy group was equally obtained in good yields. The pronounced ionic liquid effect avoids the direct formation of isatin in the acidified media and the reaction leads exclusively to isatin-3-oxime derivatives.     

Synthesis of new imidazole derivatives as potential inhibitors of thromboxane synthetase

The preparation of new imidazole derivatives containing a carboxylic moiety such as succinic, adipic or benzoic into the side chain, is reported starting from the suitable imidazole intermediates.     

From Kerr to Heisenberg

In this paper, we consider the space-time of a charged mass endowed with an angular momentum. The geometry is described by the exact Kerr–Newman solution of the Einstein equations. The peculiar symmetry, though exact, is usually described in terms of the gravito-magnetic field originated by the angular momentum of the source. A typical product of this geometry is represented by the generalized Sagnac effect. We write down the explicit form for the right/left asymmetry of the times of flight of two counter-rotating light beams along a circular trajectory. Letting the circle shrink to the origin the asymmetry stays finite. Furthermore it becomes independent both from the charge of the source (then its electromagnetic field) and from Newton’s constant: it is then associated only to the symmetry produced by the gravitomagnetic field. When introducing, for the source, the spin of a Fermion, the lowest limit of the Heisenberg uncertainty formula for energy and time appears.     

Experimental Design in Ion Chromatography: Effect of the Organic Modifier and Complexing Agent on the Retention of Alkaline and Alkaline Earth Ions

A Box–Behnken experimental design combined with response surface methodology was applied to investigate the effect of the eluent composition on the retention of common cations in ion chromatography. In particular, we modelled the retention factors of Na⁺, K⁺, NH₄ ⁺, Ca⁺⁺ and Mg⁺⁺ and the chromatogram resolution. Response surfaces were evaluated to assess interactive effects of nitric acid, pyridine-2,6-dicarboxylic acid and percentage of acetonitrile in the eluent on the above parameters. Nitric acid concentration and acetonitrile content appeared as the most and the least influential components of the eluent in determining the retention factors of individual ions or the global resolution of the chromatogram, while the concentration of the complexing agent exhibits an intermediate role. As expected, acidification of the mobile phase produces a decrease in the retention factors and a progressive worsening of resolution, and this effect can be modulated by the concentration of the complexing agent. The proposed approach seems suitable to investigate the retention phenomena in ion chromatography under application of complex eluent phases.