abstract
In the past decade, ionic liquids (ILs) have been the focus of intensive research regarding their use as potential and alternative solvents in many chemical applications. Targeting their effectiveness, recent investigations have attempted to establish polarity scales capable of ranking ILs according to their chemical behaviours. However, some major drawbacks have been found since polarity scales only report relative ranks because they depend on the set of probe dyes used, and they are sensitive to measurement conditions, such as purity levels of the ILs and procedures employed. Due to all these difficulties it is of crucial importance to find alternative and/or predictive methods and to evaluate them as a priori approaches capable of providing the chemical properties of ILs. Furthermore, the large number of ILs available makes their experimental characterization, usually achieved by a trial and error methodology, burdensome. In this context, we firstly evaluated COSMO-RS, COnductor-like Screening MOdel for Real Solvents, as an alternative tool to estimate the hydrogen-bond basicity of ILs. After demonstrating a straight-line correlation between the experimental hydrogen-bond basicity values and the COSMO-RS hydrogen-bonding energies in equimolar cation-anion pairs, an extended scale for the hydrogen-bond accepting ability of IL anions is proposed here. This new ranking of the ILs' chemical properties opens the possibility to pre-screen appropriate ILs (even those not yet synthesized) for a given task or application.
keywords
SOLVATOCHROMIC COMPARISON METHOD; AQUEOUS BIPHASIC SYSTEMS; COSMO-RS; SOLVENT PROPERTIES; SCREENING MODEL; WATER MIXTURES; BINARY-SYSTEMS; REAL SOLVENTS; PI-STAR; PREDICTION
subject category
Chemistry; Physics
authors
Claudio, AFM; Swift, L; Hallett, JP; Welton, T; Coutinho, JAP; Freire, MG
our authors
Ana Filipa M. Cláudio
Post-doc Fellowship
Mara Guadalupe Freire Martins
Coordinating ResearcherGroups
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
Projects
acknowledgements
This work was financed by national funding from FCT - Fundacao para a Ciencia e a Tecnologia, through projects PTDC/QUI-QUI/121520/2010 and PEst-C/CTM/LA0011/2013. The authors also acknowledge FCT for the PhD grant SFRH/BD/74503/2010 of A. F. M. Claudio and the FCT 2012 Investigator Programme.