[Show abstract][Hide abstract] ABSTRACT: A series of 11 new protic ionic liquids with fluorous anions (FPILs) have been identified and their self-assembled nanostructure, thermal phase transitions and physicochemical properties were investigated. To the best of our knowledge this is the first time that fluorocarbon domains have been reported in PILs. The FPILs were prepared from a range of hydrocarbon alkyl and heterocyclic amine cations in combination with the perfluorinated anions heptafluorobutyrate and pentadecafluorooctanoate. The nanostructure of the FPILs was established by using small- and wide-angle X-ray scattering (SAXS and WAXS). In the liquid state many of the FPILs showed an intermediate range order, or self-assembled nanostructure, resulting from segregation of the polar and nonpolar hydrocarbon and fluorocarbon domains of the ionic liquid. In addition, the physicochemical properties of the FPILs were determined including the melting point (T(m)), glass transition (T(g)), devitrification temperature (T(c)), thermal stability and the density ρ, viscosity η, air/liquid surface tension γ(LV), refractive index n(D), and ionic conductivity κ. The FPILs were mostly solids at room temperature, however two examples 2-pyrrolidinonium heptafluorobutyrate (PyrroBF) and pyrrolidinium heptafluorobutyrate (PyrrBF) were liquids at room temperature and all of the FPILs melted below 80 °C. Four of the FPILs exhibited a glass transition. The two liquids at room temperature, PyrroBF and PyrrBF, had a similar density, surface tension and refractive index but their viscosity and ionic conductivity were very different due to dissimilar self-assembled nanostructure.
No preview · Article · May 2012 · Physical Chemistry Chemical Physics
[Show abstract][Hide abstract] ABSTRACT: Protic ionic liquids (PILs) are a subset of ionic liquids formed by the equimolar mixing of a Bronsted acid and a Bronsted base. PILs have been categorized as poor ionic liquids. However, the issue of assessing the ionicity of PILs is still a matter of debate. In this work we studied some physicochemical properties of three chosen PILs, namely, ethanolammonium acetate (EOAA), 2-methylbutylammonium formate (2MBAF), and pentylammonium formate (PeAF), at the initial equimolar (stoichiometric) acid/base ratio and in the presence of excess acid and base. DSC phase-transition studies along with NMR, IR, and Raman spectroscopy were performed on the chosen PILs. The results are discussed in terms of the degree of ionization (extent of proton transfer from the Bronsted acid to Bronsted base), and the possibility of the formation of polar 1:1 complexes and larger aggregates in the neat stoichiometric PILs.
No preview · Article · Jan 2007 · Australian Journal of Chemistry