Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)-Dodecyl (2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium Bromide (DMEB)
(1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) aggregates dispersed in carbon tetrachloride have been investigated by Fourier transform infrared (FT-IR), vibrational circular dichroism (VCD) and 1H nuclear magnetic resonance (NMR) spectroscopy at various surfactant concentration and water-to-surfactant molar ratio. Experimental data indicate that, even at the lowest investigated concentration and in absence of added water, DMEB molecules associate in supramolecular assemblies. At higher DMEB concentration the aggregates can confine water molecules, making it plausible to think that DMEB form reverse micelles and that water molecules are quite uniformly dist…
Direct experimental observation of mesoscopic fluorous domains in fluorinated room temperature ionic liquids
Fluorinated room temperature ionic liquids (FRTILs) represent a class of solvent media that are attracting great attention due to their IL-specific properties as well as features stemming from their fluorous nature. Medium-to-long fluorous tails constitute a well-defined apolar moiety in the otherwise polar environment. Similarly to the case of alkyl tails, such chains are expected to result in the formation of self-assembled fluorous domains. So far, however, no direct experimental observation has been made of the existence of such structural heterogeneities on the nm scale. We report here the first experimental evidence of the existence of mesoscopic spatial segregation of fluorinated dom…
Spectroscopic and Structural Investigation of the Confinement of D and L Dimethyl Tartrate in Lecithin Reverse Micelles
The confinement of D and L dimethyl tartrate in lecithin reverse micelles dispersed in cyclohexane has been investigated by FT-IR, polarimetry, electronic and vibrational circular dichroism (ECD and VCD), 1H NMR, and small-angle X-ray scattering (SAXS). Measurements have been performed at room temperature as a function of the solubilizate-to-surfactant molar ratio (R) at fixed lecithin concentration. The analysis of experimental data indicates that the dimethyl tartrate molecules are solubilized within reverse micelles in proximity to the surfactant head groups in the same way for the D and L forms. The encapsulation of dimethyl tatrate within lecithin reverse micelles involves changes in i…
Multiple points of view of heteronuclear NOE: long range vs short range contacts in pyrrolidinium based ionic liquids in the presence of Li salts.
The nuclear Overhauser enhancement (NOE) is a powerful tool of NMR spectroscopy extensively used to gain structural information in ionic liquids (ILs). A general model for the distance dependence of intermolecular NOE in ILs was recently proposed showing that NOE spots beyond the first solvation shell and accounts for long-range effects. This conclusion prompted for a deep rethinking of the NOE data interpretation in ILs. In this paper we present an extensive and quantitative study of N-propyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI), the homologue with bis(fluorosulfonyl)imide (PYR13FSI), and their mixtures with LiTFSI based on 1H-19F and 1H-7LiNOE correlation …