Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

We describe a multidentate tripodal ligand in which three pendant arms carrying di(2-picolyl)amine units are linked to the ortho positions of a tris(o-xylyl) scaffold, providing N(CH[subscript 2]-o-C[subscript 6]H[subscript 4]CH[subscript 2]N(CH2py)[subscript 2])[subscript 3] (L). Reaction of L with CuCl[subscript 2] in the presence of hexafluorophosphate anion afforded blue cubes of [(CuCl)[subscript 3]L](PF[subscript 6])[subscript 3]·5H[subscript 2]O (1). Crystallographic studies of 1 revealed that the three symmetry-related arms each coordinate a {Cu[superscript II]Cl} unit, and two molecules of 1 are connected to one another through a Cu(μ-Cl)[subscript 2]Cu bridge, extending the molecular structure to form a two-dimensional (2-D) layer. These 2-D layers pack in an ABCABC... fashion with PF[subscript 6]– anions located in between. Reaction of 1 with a stoichiometric amount of perrhenate ion afforded blue plates of [(CuCl)[subscript 3]L](PF[subscript 6])(ReO[subscript 4])[subscript 2]·3H[subscript 2]O (2). Compound 2 has the same lattice structure as 1, but the tricopper unit backbone now traps one ReO[subscript 4]– anion through Coulombic interactions. In addition, three molecules of 2 are bridged by a perrhenate ion, forming a Cu[subscript 3](μ[superscript 3]-ReO[subscript 4]) cluster, to give a different 2-D structure displaying a rare tridentate bridging ReO[subscript 4]– mode. Thus, in addition to classic perrhenate trapping through weak Coulombic interactions, 2 represents an exceptional example in which the ReO[subscript 4]– anion is immobilized in an extended framework through tight covalent interactions. The interlamellar PF[subscript 6]– anions in 1 can be exchanged with other anions including perrhenate, perchlorate, or periodate. The structural similarity between perrhenate and pertechnetate makes these materials of potential interest for pertechnetate trapping

Jerboa : a graph transformation library for topology-base geometric modeling

International audienc

Characterization of dielectric walls of capacitors

This work presents the preliminary results of a study that proposes the development of capacitors with similar or better performance in terms of reliability and partial discharges (PD) level than their oil-impregnated counterparts. It presents the comparison of several configurations and technologies of layered dielectric films capacitors impregnated with a commercial polymeric resin, with the aim to improve the properties of its inner dielectric wall. To find a suitable match between the different dielectric film arrangements and technologies with the polymeric resin used, tests on different sample configurations were carried out. These tests also covered the impact of the surface treatment prior to impregnation and the final enhancement of dielectric properties of the system due to the encapsulating polymeric resin. To ensure a reliable fabrication process, the Vacuum Pressure Impregnation (VPI) technique was used. The results show that rough polypropylene (PPR) films with prior surface treatment and set in polymeric resin may be the best candidate to compete with current technologies to carry out oil-free capacitors

The Enforcement of Provisional Measures

The chapter examines the various legislative models for the enforcement of arbitral tribunals' provisional measures, including measures issued by emergency arbitrator