Synthese et application de nouveaux sulfures a chaine perfluoree

Metallation of thiols R_FC₂H₄SH followed by alkylation with iodides R′_FC₂H₄I leads either to symmetrical or to unsymmetrical sulphides R_FC₂H₄SC₂H₄R′_F (with R_F=R′_F or R_F ≠ R′_F). All compounds obtained are good solvents of gases (particularly O₂, CO, CO₂, N₂).This property allows their application as biological carriers of dissolved gases.     

Saddle‐Shaped Cyclic Indole Tetramers: 3D Electroactive Molecules

We present a joint theoretical and experimental study of a series of cyclic indole tetramers aimed at understanding the fundamental electronic properties of this 3D platform and evaluating its potential in the construction of new semiconductors. To this end, we combined absorption and Raman spectroscopy, cyclic voltammetry, and spectroelectrochemistry with DFT calculations. Our results suggest that this platform can be easily and reversibly oxidized. Additionally, it has a HOMO that matches very well with the workfunction of gold, therefore charge injection from a gold electrode is expected to occur without significant barriers. Interestingly, the cyclic tetraindoles allow for good electron delocalization in spite of their saddle‐shaped structures. The steric constraints introduced by N‐substitution significantly inhibits ring inversion of the central cyclooctatetraene unit, whereas it only barely affects the optical and electrochemical properties (a slightly higher oxidation potential and a blueshifted absorption upon alkylation are observed).     

Transition metal complexes with pyrazole-based ligands. Part 28. Synthesis,structural, DFT and thermal studies of cadmium(II) halides and zinc(II) chloride complexes with 3,5-dimethylpyrazole-1-carboxamidine

The complex formation of 3,5-dimethylpyrazole-1-carboxamidinium nitrate, HL·HNO₃ with ammine complexes of cadmium(II) halides (Cl, Br, I) and zinc(II) chloride has been investigated under self-controlled reaction conditions. The complexes have been characterized by X-ray diffraction, FT-IR spectroscopy, thermal analysis and quantum chemical calculations. In the case of cadmium bromide and iodide salts, isostructural complexes with composition of [CdX₂(HL)₂] were formed. With CdCl₂ a binuclear octahedral [Cd₂(HL)₄(μ-Cl)₂](NO₃)₂ complex is obtained. Zinc(II) chloride with HL·HNO₃ gives [Zn(HL)₂Cl]NO₃, the zinc center exhibiting severely distorted five-coordinate stereochemistry, intermediate between an ideal trigonal bipyramid and a square pyramid. The course of complex formation as well as the thermal properties of the compounds has been explained using the HSAB principle. The assignment of the FT-IR spectra was supported by DFT computations.     

The Interaction of α‐Hydroxycarboxylic Acids with Metal Ions: Lactic Acid (H2L1) and 2‐Methyllactic Acid (H2L2) with Cobalt(II) Crystal and Molecular Structures of [Co(HL1)2(H2O)2]·H2O and [Co(HL2)2(H2O)2]

The cobalt(II) complexes [Co(HL¹)₂(H₂O)₂]·H₂O) ( 1 ) and [Co(HL²)₂(H₂O)₂]( 2 ) [(HL¹)^‐ = (/plusmn;)‐lactate, (HL²)^‐ = 2‐Methyl‐lactate] were prepared and characterized structurally. The cobalt atom is in a distorted octahedral environment in both compounds. Both α‐hydroxycarboxylato ligands are O, O'‐bidentate chelating monoanions. The presence of a lattice water molecule in 1 makes its supramolecular organization different from that of 2 . The thermal behaviour of both compounds was also investigated.     

Semidefinite programming hierarchies for constrained bilinear optimization

Mathematical Programming - We give asymptotically converging semidefinite programming hierarchies of outer bounds on bilinear programs of the form $${mathrm {Tr}}big [H(Dotimes E)big ]$$ ,...     

Hydrothermal Synthesis,Crystal Structures and Effect of Non Bonding Interactions in Crystal Packing of Two Mixed‐Ligand Metal Complexes with Glycolato and 2,2′‐Dipiridylamine and with Benzilato and Imidazole

Two new mixed‐ligand complexes [Fe(HG)₂(dipyam)] ( 1 ) (HG = glycolato and dipyam = 2,2′‐dipyridylamine) and [Cu(HB)₂(im)₂]·2H₂O ( 2 ) (HB = benzilato and im = imidazole) have been hydrothermally synthesized and structurally characterised by X‐ray diffraction. In both cases the metallic centre is in an octahedral environment, strongly distorted in 2 (4+2 coordination). The α‐hydroxycarboxylato ligands (glycolato or benzilato) present different coordinative behaviour, bidentade chelate through the hydroxyl oxygen and one carboxy oxygen in 1 and through the two oxygen atoms of the carboxylate group in 2 . The complexes are extended into 2D frameworks through hydrogen bonding and π···π or C‐H···π interactions. The complexes were also characterized by elemental analysis, FT‐IR and UV‐vis spectroscopy and room temperature magnetic measurements.     

Crystallographic report: Bis(2‐diphenylglycolato‐O)bis(1,10‐phenanthroline‐N,N′)zinc(II), [Zn(C14H11O3)2(C12H8N2)2]

The structure of [Zn(HB)₂(1,10‐phen)₂] (HB = diphenylglycolato) comprises mononuclear molecules with the zinc(II) cation situated on a two fold axis and octahedrally coordinated by an N₄O₂ donor set. Copyright © 2004 John Wiley & Sons, Ltd.     

Parameters Involved in the Sol-Gel Transition of Titania in Reverse Micelles

Titania nanoparticles and gels are synthesized in reverse micelles with either an ionic (AOT) or a non-ionic (Triton X-100) surfactant in alkanes with low water contents. Acids were in some cases dissolved in the aqueous phase. Whereas the size of the sol nanoparticles is independent of the micellar composition, the kinetics of the sol-gel transition are not. The gelation time is shorter for the non-ionic surfactant and becomes longer as the acid content in the water increases, and for smaller anions of equal charge.     

A MASSive Laboratory Tour. An Interactive Mass Spectrometry Outreach Activity for Children

It is imperative to fascinate young children at an early stage in their education for the analytical sciences. The exposure of the public to mass spectrometry presently increases rapidly through the common media. Outreach activities can take advantage of this exposure and employ mass spectrometry as an exquisite example of an analytical science in which children can be fascinated. The presented teaching modules introduce children to mass spectrometry and give them the opportunity to experience a modern research laboratory. The modules are highly adaptable and can be applied to young children from the age of 6 to 14 y. In an interactive tour, the students explore three major scientific concepts related to mass spectrometry; the building blocks of matter, charged particle manipulation by electrostatic fields, and analyte identification by mass analysis. Also, the students carry out a mass spectrometry experiment and learn to interpret the resulting mass spectra. The multistage, inquiry-based tour contains flexible methods, which teach the students current-day research techniques and possible applications to real research topics. Besides the scientific concepts, laboratory safety and hygiene are stressed and the students are enthused for the analytical sciences by participating in “hands-on” work. The presented modules have repeatedly been successfully employed during laboratory open days. They are also found to be extremely suitable for (early) high school science classes during laboratory visit-focused field trips.