AUTHOR=Han Qi , Wang Xungai , Bynre Nolene 

TITLE=Utilizing Water Activity as a Simple Measure to Understand Hydrophobicity in Ionic Liquids

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00112

DOI=10.3389/fchem.2019.00112

ISSN=2296-2646

ABSTRACT=<p>Ionic liquids (ILs) are regarded as designable solvents finding use in a variety of applications. One of the challenges of the design and selection process is to understand the ionic liquid properties. In this work, we selected seven ILs containing three types of hydrophilic anions and examined several key properties, which are correlated to hydrophobicity. In particular, we measured the hydrogen bond basicity β and water activity a<sub>w</sub> of IL and IL-water mixtures, and suggested that these two properties are linearly correlated particularly in hydrated ILs. We then used NMR to evaluate the chemical shift of H<sub>2</sub>O in hydrated ILs. Correlating the outcomes of each of these techniques with respect to understanding the hydrophobicity of the ILs is discussed. It is shown that water activity a<sub>w</sub> is the most facile technique to represent and understand hydrophobicity of ILs.</p>