Search results for "TRIF"
showing 10 items of 1419 documents
Spin transition in three-dimensional bridged coordination polymers of iron(II)–urea-triazoles
2008
Abstract Three-dimensional spin-crossover (SCO) networks of [Fe 2 ( n -Rdubtrz) 3 ](X) 4 · n H 2 O ( n -R = (CH 2 ) y , y = 4, 6, 8, 12; du = diurea; btrz = bis-triazole; X = BF 4 - , ClO 4 - , triflate, tosylate) coordination polymers are prepared by reaction of bridging aliphatic bis-urea triazoles ( n -Rdubtrz) with the iron-salts (FeX 2 ). Investigations of the properties are supported by studies of one-dimensional compounds of [Fe(Rtrzu) 3 ](X) 2 (R = n -propyl, t -butyl; trzu = urea triazole). Characterization of the complexes is carried out with IR-spectroscopy, elemental analysis, TGA and atomic absorption spectroscopy. SCO-behaviour of all complexes is inspected by magnetic sus…
Chemical and acidic composition of Longissimus dorsi muscle of Comisana lambs fed with Trifolium subterraneum and Lolium multiflorum
2010
Aim of this study was to evaluate the effects of grazing on Trifolium subterraneum and Lolium multiflorum, as pure or associated crops, on the chemical composition and on the fatty acid profile of the intramuscular lipids of the meat of lambs. Forty Comisana male lambs, on average weighing 13.75±1.90 kg, were divided into four homogenous groups of ten and called, in relation to the diet: group T those grazing on T. subterraneum; Group L on L. multiflorum; Group TL on adjacent monocultures of T. subterraneum and L. multiflorum (66.6 and 33.3% of surface, respectively); Group LT on adjacent monocultures of T. subterraneum and L. multiflorum (33.3 and 66.6% of surface, respectively). Every 10 …
The role of intermolecular forces in contact electrification on polymer surfaces and triboelectric nanogenerators
2019
This research was supported by the European Regional Development Fund within the project ‘‘Hybrid energy harvesting systems’’ 1.1.1.1./16/A/013.
Self-assembly and anion encapsulation properties of cavitand-based coordination cages.
2001
Two novel classes of cavitand-based coordination cages 7a--j and 8a--d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P--M--P angle close to 90 degrees between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic (1)H and (19)F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d r…
Optically active amphiphilic hyperbranched polyglycerols as templates for palladium nanoparticles
2006
Abstract We report a systematic study on the encapsulation of palladium nanoparticles in optically active amphiphilic hyperbranched polyglycerols with different optical signs and different degrees of polymerization, namely (−)-P(G 40 C16 0.5 ) 1 and (+)-P(G 73 C16 0.5 ) 2 . Several issues have been addressed here: (a) relatively wide size distributions (1–5 nm) of palladium nanoparticles have been achieved, (b) a remarkable template effect ( 1 , DP n = 40, 1.2 ± 0.1 nm; 2 , DP n = 73, 2.3 ± 0.1 nm average particle size) has been observed using TEM technique, as shown by the particle size dependent on the degree of polymerization of the polymers, (c) NaBH 4 is found to be a convenient redu…
Synthesis and Physicochemical Characterization ofmeso-Functionalized Corroles: Precursors of Organic-Inorganic Hybrid Materials
2005
Cobalt(III) corroles exhibit an infinite selectivity for the coordination of carbon monoxide towards dioxygen and dinitrogen. This peculiar property thus allows their use as sensing devices for CO detection. Here are described the syntheses and physico-chemical characterization of meso mono-, bis- and tris(triethoxysilyl)-functionalized corroles, precursors of organic–inorganic materials. The corrole ring formation was achieved in every case using the “2+1” method involving the reaction of two equivalents of an encumbered dipyrromethane with one equivalent of an aromatic aldehyde in the presence of a catalytic amount of trifluoroacetic acid. The functionalization of the corrole by triethoxy…
Molecular dynamics simulations of the glass transition in polymer melts
2004
Computer simulations of polymer models have contributed strongly to our understanding of the glass transition in polymer melts. The ability of the simulation to provide information on experimentally not directly accessible quantities like the detailed spatial arrangement of the particles allows for stringent tests of theoretical concepts about the glass transition and provides additional insight for the interpretation of experimental data. Comparing coarse-grained simulations of a bead-spring model and chemically realistic simulations of 1,4-polybutadiene the importance of dihedral barriers for the glass transition phenomenon can be elucidated.
Oxyfunctionalization of Aliphatic Esters by Methyl(trifluoromethyl)dioxirane
1996
The oxidation of lineal, cyclic, and bicyclic aliphatic p-chlorobenzoic and p-chorobenzenesulfonic acid esters 2 with methyl(trifluoromethyl)dioxirane (TFDO) (1) occurs at positions in the hydrocarbon chain distant from the directing group with a significant degree of selectivity to give the corresponding keto or hydroxy esters. Compounds 2 are relatively deactivated with respect to this oxidation due to the electron-withdrawing nature of the ester moiety. Methylene Cα−H and Cβ−H bonds remain unchanged in all cases, but tertiary Cβ−H bonds undergo oxidation with TFDO (1). Stereoelectronic factors are used to explain the faster reaction rate in competition experiments for the oxidation of en…
Solvent-free ruthenium-catalysed triflate coupling as a convenient method for selective azole-o-C-H monoarylation.
2019
Metal-catalysed ortho-directed C–H functionalization usually faces selectivity issues in the competition between mono- and disubstitution processes. We report herein the ruthenium-catalysed N-directed C–H monoarylation of arylpyrazoles with a selectivity of up to 96% or that generally reaches values above 80%. This selectivity is an effect of solvent-free conditions associated with sulfonate reagents, in the absence of frequently used acidic additives.
Racemic and Optically Pure Heptahelicene-2-carboxylic Acid: Its Synthesis and Self-Assembly into Nanowire-Like Aggregates
2010
Heptahelicene-2-carboxylic acid was effectively synthesised from suitably functionalised naphthalene building blocks. Methoxy-substituted 1,1'-ethyne-1,2-diylbis(2-but-3-yn-1-ylnaphthalene) was cyclised in the presence of CpCo(CO)(2)/PPh(3) to 2-methoxy-7,8,11,12-tetrahydroheptahelicene, which was converted into heptahelicen-2-yl trifluoromethanesulfonate. This reactive intermediate underwent Pd(OAc)(2)/dppp-catalysed methoxycarbonylation reaction to provide, after hydrolysis, heptahelicene-2-carboxylic acid. The racemate was resolved into enantiomers by semipreparative HPLC on a chiral column. The helicity of (+)-(P)-heptahelicene-2-carboxylic acid was assigned by correlating its CD spectr…