Silica ionogels synthesized with imidazolium based ionic liquids in presence of supercritical CO2

Silica ionogels were synthesized using the one step sol-gel route. Imidazolium based ionic liquids (ILs) containing different cations and anions were used in order to investigate their effect as co-solvent and co-catalyst on the gelation time and on the solid properties (pore size, surface area, pore volume, hydrophobicity) of the final material. The influence of the ionic liquid concentration on the gelation time was also determined. Experiments under high pressure in presence of supercritical carbon dioxide were additionally performed. The obtained ionogels were dried with supercritical CO2 and analyzed by scanning electron microscopy (SEM), 1H and 19F magic-angle spinning nuclear magnetic resonance (MAS NMR) and nitrogen adsorption-desorption isotherms (BET)

Intense near-infrared luminescence of anhydrous lanthanide(III) iodides in an imidazolium ionic liquid

Anhydrous neodymium(III) iodide and erbium(Ill) iodide were dissolved in carefully dried batches of the ionic liquid 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(12)mim][Tf2N]. Provided that the ionic liquid had a low water content, intense near-infrared emission could be observed for both the neodymium(III) ion and for the erbium(III) ion. Luminescence lifetimes have been measured, and the quantum yield of the neodymium(III) sample has been measured. Exposure of the hygroscopic samples to atmospheric moisture conditions caused a rapid decrease of the luminescence intensities.status: publishe

Strong luminescence of rare earth compounds in ionic liquids: Luminescent properties of lanthanide(III) iodides in the ionic liquid 1-dodecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide

Purposely designed ionic liquids can be excellent solvents for spectroscopic studies of rare earth compounds. Absorption, excitation and emission spectra of LnI(3) (Ln =Nd, Dy and Tb) in the ionic liquid 1-dodecyl-3-methylimidazoliumbis(trifluoromethanesulfonyl)imide are presented. Electronic transitions were assigned from the energy level diagrams for Ln(III). Emission lifetimes for DyI3 in [C(12)mim][Tf2N] are discussed. Traces of water dramatically reduce the otherwise long lifetimes and comparatively high quantum yields.status: publishe

Influence of scCO(2), ultrasound, and quaternary ammonium salt on gelation time and structural characteristics of silica

In situ synthesis of silica gels via a one-step sol-gel process at ambient pressure or in supercritical CO2 was investigated. The influence of compressed gas, ultrasound irradiation, and quaternary ammonium salt (choline chloride) on the gelation time was determined. The obtained samples were characterized by N-2 adsorption/desorption measurements, scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR). The retention capacity of the corresponding silica aerogels for Rhodamine B was evaluated as a model for organic water pollutants. The obtained results proved that scCO(2) has a beneficial effect, leading to a reduction of the gelation time. The obtained aerogels exhibit a higher surface area and larger pore diameter as well as a well-defined cylindrical pore structure