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Ionic Nature (ionic + nature)
Selected AbstractsSynthesis and Optoelectronic Properties of Nonpolar Polyrotaxane Insulated Molecular Wires with High Solubility in Organic Solvents,ADVANCED FUNCTIONAL MATERIALS, Issue 21 2008Michael J. Frampton Abstract Hydrophilic polyanionic conjugated polyrotaxanes are readily synthesized in water by Suzuki coupling, but their high polarity and ionic nature limit the potential applications of these materials. Here, we demonstrate three methods for transforming these polar polyelectrolytes into nonpolar lipophilic insulated molecular wires. A water-soluble polyfluorene- alt -biphenylene ,-cyclodextrin (CD) polyrotaxane was converted into nonpolar derivatives by methylation of the carboxylic acid groups with diazomethane and conversion of the hydroxyl groups of the CDs to benzyl ethers, trihexylsilyl ethers, benzoyl esters, and butanoate esters to yield polyrotaxanes that are soluble in organic solvents such as chloroform and cyclohexane. Elemental analysis, NMR spectroscopy, and gel permeation chromatography (GPC) data support the proposed structures of the organic-soluble polyrotaxanes. The extents of reaction of the polyrotaxane CD hydroxyl groups were 55% for trihexylsilyl chloride/imidazole; 81% for benzyl chloride/sodium hydride; 72% for benzoyl chloride/pyridine/4-dimethylaminopyridine; and 98% butanoic anhydride/pyridine/4-dimethylaminopyridine. Alkylation, silylation, and esterification increase the bulk of the encapsulating sheath, preventing interstrand aggregation, increasing the photoluminescence efficiency in the solid state and simplifying the time-resolved fluorescence decay. The organic-soluble polyrotaxanes were processed into polymer light-emitting diodes (PLEDs) from solution in nonpolar organic solvents, thereby excluding ionic impurities from the active layer. [source] Kinetic investigation on the oxidation of nitrite by oxochromium(V) ion in aqueous and micellar systemsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2004Mookandi Kanthimathi The kinetics of oxidation of nitrite by [O = CrV (5-chlorosalen)]+ complex has been studied spectrophotometrically at [CrV] = 0.5 × 10,3 M, [NO2,] = 0.01,0.1 M, [H+] = 0.0001,0.05 M, I = 0.15 M, and T = 25°C in the presence of cationic surfactant, cetyl pyridium chloride (CPC), and anionic surfactant, sodium dodecyl sulfate (SDS),in aqueous acidic medium. The oxygen atom transfer reaction from O = CrV to nitrite ion is influenced by the ionic nature of the micelle. The redox reaction is accelerated in presence of CPC and slowed down by 40 times in presence of SDS. The mechanism of the reaction involves an inner-sphere process involving the formation of an intermediate followed by oxo transfer process. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 79,86 2004 [source] Local characteristics of the electronic structure of MgO: LCAO and plane-wave calculationsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2005R. A. Evarestov Abstract Linear combinations of atomic orbitals and plane-wave calculations of the electronic structure of the ionic crystal MgO were performed. Local characteristics of the electronic structure of this crystal are obtained using the traditional approaches and the method based on Wannier-type atomic orbitals (WTAOs). It is demonstrated that the results of the conventional methods for chemical bonding analysis in MgO are contradictory and unreasonable. On the contrary, the results of the WTAO method for both types of the basis correctly exhibit the ionic nature of chemical bonding in this crystal. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Atom transfer radical polymerization of styrenic ionic liquid monomers and carbon dioxide absorption of the polymerized ionic liquidsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2005Huadong Tang Abstract Polymeric forms of ionic liquids have many potential applications because of their high thermal stability and ionic nature. Two ionic liquid monomers, 1-(4-vinylbenzyl)-3-butyl imidazolium tetrafluoroborate (VBIT) and 1-(4-vinylbenzyl)-3- butyl imidazolium hexafluorophosphate (VBIH), were synthesized through the quaternization of N -butylimidazole with 4-vinylbenzylchloride and a subsequent anion- exchange reaction with sodium tetrafluoroborate or potassium hexafluorophosphate. Copper-mediated atom transfer radical polymerization was used to polymerize VBIT and VBIH. The effects of various initiator/catalyst systems, monomer concentrations, solvent polarities, and reaction temperatures on the polymerization were examined. The polymerization was well controlled and exhibited living characteristics when CuBr/1,1,4,7,10,10-hexamethyltriethylenetetramine or CuBr/2,2,-bipyridine was used as the catalyst and ethyl 2-bromoisobutyrate was used as the initiator. Characterizations by thermogravimetric analysis, differential scanning calorimetry, and X-ray diffraction showed that the resulting VBIT polymer, poly[1-(4-vinylbenzyl)-3-butyl imidazolium tetrafluoroborate] (PVBIT), was amorphous and had excellent thermal stability, with a glass-transition temperature of 84 °C. The polymerized ionic liquids could absorb CO2 as ionic liquids: PVBIT absorbed 0.30% (w/w) CO2 at room temperature and 0.78 atm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1432,1443, 2005 [source] | |||||||||||||