Search results for "fluorinated"
showing 10 items of 99 documents
Correlated effects of fluorine and hydrogen in fluorinated tin oxide (FTO) transparent electrodes deposited by sputtering at room temperature
2021
The optical and electrical properties of fluorinated tin oxide (FTO) films deposited at room temperature by sputtering have been investigated varying the fluorine content and the hydrogen atmosphere. The complex behavior of the obtained films is disclosed using a wide set of characterization techniques that reveals the combined effects of these two parameters on the generated defects. These defects control the electrical transport (carrier density, mobility and conductivity), the optical properties (band gap and defects-related absorption and photoluminescence) and finally promote the amorphization of the samples. H2 in the sputtering gas does not modify the H content in the films but induc…
Pickering Emulsions of Fluorinated TiO2: A New Route for Intensification of Photocatalytic Degradation of Nitrobenzene
2020
International audience; Fluorination of the TiO2 surface has been often reported as a tool to increase the photocatalytic efficiency due to the beneficial effects in terms of production of oxidizing radicals. Moreover, it is shown that the unique amphiphilic properties of the fluorinated TiO2 (TiO2-F) surface allow one to use this material as a stabilizer for the formulation of Pickering emulsions of poorly soluble pollutants such as nitrobenzene (NB) in water. The emulsions have been characterized in terms of size of the droplets, type of emulsion, possibility of phase inversion, contact angle measurements, and optical microscopy. The emulsified system presents micrometer-sized droplets of…
Carrier transport mechanism in the SnO(2):F/p-type a-Si:H heterojunction
2011
We characterize SnO(2):F/p-type a-Si:H/Mo structures by current-voltage (I-V) and capacitance-voltage (C-V) measurements at different temperatures to determine the transport mechanism in the SnO2:F/p-type a-Si:H heterojunction. The experimental I-V curves of these structures, almost symmetric around the origin, are ohmic for vertical bar V vertical bar< 0:1 V and have a super-linear behavior (power law) for vertical bar V vertical bar < 0:1 V. The structure can be modeled as two diodes back to back connected so that the main current transport mechanisms are due to the reverse current of the diodes. To explain the measured C-V curves, the capacitance of the heterostructure is modeled as the …
Mesoscopic structural organization in fluorinated pyrrolidinium-based room temperature ionic liquids
2019
Abstract In this contribution the microscopic and mesoscopic structural organization in a series of fluorinated room temperature ionic liquids, based on N-methyl-N-alkylpyrrolidinium cations and on bis(perfluoroalkylsulfonyl)imide anions, is investigated, using a synergy of experimental (X-ray and neutron scattering) and computational (Molecular Dynamics) techniques. The proposed ionic liquids are of high interest as electrolyte media for lithium battery applications. Together with information on their good ion transport properties in conjunction with low viscosity, we also describe the existence of nm-scale spatial organization induced by the segregation of fluorous moieties into domains. …
Improved Regioselectivity in Pyrazole Formation through the Use of Fluorinated Alcohols as Solvents: Synthesis and Biological Activity of Fluorinated…
2008
The preparation of N-methylpyrazoles is usually accomplished through reaction of a suitable 1,3-diketone with methylhydrazine in ethanol as the solvent. This strategy, however, leads to the formation of regioisomeric mixtures of N-methylpyrazoles, which sometimes are difficult to separate. We have determined that the use of fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents dramatically increases the regioselectivity in the pyrazole formation, and we have used this modification in a straightforward synthesis of fluorinated analogs of Tebufenpyrad with acaricide activity. Fil: Fustero, Santos. Universidad de Valencia; España Fil…
On the reaction of some 5-polyfluoroaryl-1,2,4-oxadiazoles with methylhydrazine: synthesis of fluorinated indazoles
2009
The reaction of 5-polyfluoroaryl-1,2,4-oxadiazoles with methylhydrazine has been studied and the synthesis of fluorinated N-methylindazoles has been realized. Rearrangement reactions showed predominantly formation of N(1)-methylindazole regioisomers. Starting compounds were preliminarily functionalized at the polyfluoroaryl moiety through fluorine displacement with nucleophiles (methanol, methylamine, dimethylamine), allowing the obtainment of target indazoles substituted at the C(6) position.
Halloysite Nanotube with Fluorinated Lumen: Non-Foaming Nanocontainer for Storage and Controlled Release of Oxygen in Aqueous Media
2014
Halloysite clay nanotubes were selectivity modified by adsorbing perfluoroalkylated anionic surfactants at the inner surface. The modified nanotubes formed kinetically stable dispersions due to the enhanced electrostatic repulsions exercised between the particles. We proved that the modified nanotubes can be used as non-foaming oxygen nanocontainers in aqueous media. The gas release from supersaturated dispersions can be controlled by external stimuli and system composition. In conclusion, we managed to put forward an easy strategy to develop smart materials from natural nanoclays, which can endow important applications like the storage and delivery of gas.
A Versatile Synthesis of Fluorinated Uracils in Solution and on Solid-Phase.
2004
[reaction: see text] An efficient and convenient two-step synthesis of new fluorinated uracils is described. The first step involves the condensation of an ester enolate with a fluorinated nitrile to furnish fluorinated beta-enamino esters. In turn, these compounds react with organic isocyanates or isothiocyanates to give C-6 fluorinated uracils or thiouracils, respectively, in excellent yields. This synthesis has been successfully adapted to solid-phase conditions with high diversity, thereby facilitating the creation of small (thio)uracil libraries.
Synthesis of fluorinated 1,2,4-oxadiazin-6-ones through ANRORC rearrangement of 1,2,4-oxadiazoles
2009
Abstract The reaction of 3-ethoxycarbonyl-5-perfluoroalkyl-1,2,4-oxadiazoles with hydroxylamines has been investigated, evidencing the possibility of competitive reaction paths. Nucleophilic addition of hydroxylamine to the electrophilic C(5) of the 1,2,4-oxadiazole ring, followed by ring-opening and ring-closure with enlargement, leads to high yield and in very mild experimental conditions to the formation of 5-hydroxyamino-3-perfluoroalkyl-6 H -1,2,4-oxadiazin-6-ones, one of these presenting water gelation ability. In turn, reactions with N -methylhydroxylamine lead the exclusive formation of 4-perfluoroacylamino-2-methyl-2 H -1,2,5-oxadiazol-3-ones through the well known Boulton–Katritzk…
Synthesis of Fluorinated Bent-Core Mesogens (BCMs) Containing the 1,2,4-Oxadiazole Ring
2015
New fluorinated bent-core mesogens containing the 1,2,4-oxadiazole or 1,2,4-triazole nucleus have been synthesized taking advantage of the ANRORC (Addition of Nucleophile, Ring-Opening, Ring-Closure) reactivity of 5-perfluoroalkyl-1,2,4-oxadiazoles. Physical state changes of the obtained compounds were characterized through DSC, POM, and SAXS. Besides the formation of a smectic mesophase, a novel behavior as organic molecular glass was evidenced for some 1,2,4-oxadiazole derivatives.