Search results for " chimica"
showing 10 items of 3438 documents
STABILITY AND ORGANOCATALYTIC EFFICIENCY OF N-HETEROCYCLIC CARBENES ELECTROGENERATED IN ORGANIC SOLVENTS FROM IMIDAZOLIUM IONIC LIQUIDS
2015
The kinetic of degradation of 1-butyl-3-methylimidazole-2-ylidene (selected as model N-heterocyclic carbene - NHC), generated in organic solvents by cathodic reduction of the parent 1-butyl-3- methylimidazolium salts BMIm-X, was studied by a simple voltammetric analysis. The effect of NHC degradation rate on the efficiency of an organocatalyzed reaction (the synthesis of g-butyrolactone from cinnamaldehyde and trifluoromethylacetophenone) was investigated. The nature of the solvent and of the anion X have a remarkable effect on the stability of the NHC, the bis(trifluoromethylsulfonyl) imide anion being the best for a long lasting carbene (while acetonitrile seems to be the worst solvent). …
Innovative smart materials designed for environmental purposes
2014
As the filler influences morphology, mechanical properties and thermal degradation of a polymer
2013
Catalizzatori a base di nanocorni di carbonio-liquidi ionici per la conversione della CO2
2017
Nel presente lavoro sono stati impiegati nanocorni di carbonio (CNHs) come piattaforma catalitica per il design di nuovi materiali ibridi a base di sali di imidazolio per la conversione della CO2 in carbonati ciclici. A tale scopo sono stati preparati una serie di catalizzatori eterogenei mediante una procedura sintetica one-pot basata sulla polimerizzazione radicalica di vari sali di bis vinilimidazolio in presenza di nanocorni di carbonio. I suddetti materiali sono stati caratterizzati e testati con successo per la reazione di fissazione della CO2 in epossidi (Figura 1). Figura 1 Conversione della CO2 catalizzata da liquidi ionici supportati su CNHs Le performances catalitiche, valutate i…
A new preparation method of nanolime dispersion for the conservation of artworks
2011
Microwave-assisted synthesis of semiconductor nanoparticles in water/oil microemulsion
2005
Stable CdS and ZnS nanoparticles with exalted luminescence properties have been obtained in water/sodium bis (2-ethylhexyl) sulfosuccinate (AOT)/n-heptane microemulsion using microwave in order to take away selectively water molecules from microemulsion system. The nanoparticles synthesis was performed using a microwave exposure set-up opportunely assembled that allows irradiating the reactor with microwave of 2.45 GHz maintaining constant the temperature. The nanoparticles growth kinetics, as a function of irradiation time, was performed by means of UV-Vis spectroscopy. Information about the structural changes that microemulsion undergoes when irradiated with microwave was obtained by mean…
Structural and Optical Properties of Novel Surfactant Coated Yb@TiO2 Nanoparticles.
2010
Dimensional control of self-structuring polyoxometalates at surfaces
2009
Alcohol-Selective Oxidation in Water under Mild Conditions via a Novel Approach to Hybrid Composite Photocatalysts
2015
Abstract The oxidation of alcohols to carbonyl compounds in a clean fashion (i.e., with water as a solvent or under solvent‐free conditions, and using O2 or H2O2 as the primary oxidant) is the subject of considerable research efforts. A new approach for the selective oxidation of soluble aromatic alcohols in water under mild conditions via a novel composite photocatalyst has been developed. The catalyst is synthesized by grafting 4‐(4‐(4‐hydroxyphenylimino)cyclohexa‐2,5dienylideneamino)phenol and silver nanoparticles onto the surface of moderately crystalline titanium dioxide. The titanium dioxide‐based composite was first extensively characterized and then employed in the catalytic oxidati…
Programmable surface-architectures derived from hybrid polyoxometalate-based clusters
2011
The exploration of the self-organization of a range of the polyoxometalate-based molecular structures reveals a diverse range of surface patterns and morphologies on solid substrates of technological interest, including methylated and hydroxylated silicon surfaces (namely, SiCH3 and SiOH). By exploiting the interplay between the intrinsic molecular properties and the surface chemistry as well as dynamic spatiotemporal phenomena (e.g., dewetting), we show that these systems can yield 0D, 2D, and 3D architectures via solution deposition at the solid surface, including nanodots, discs, lamellas, porous networks, and layer-by-layer assemblies. In general, we observed that layer-by-layer growth …