Frederik PHILIPPI1,3, Daniel RAUBER2, Christopher KAY2, Tom WELTON3
1Yokohama National University, Yokohama, Japan
2Saarland University, Saarbrücken, Germany
3Imperial College London, London, United Kingdom
The purely empirical optimisation of ionic liquids is not feasible due to the large number of possible ions and ion combinations. The much more efficient ‘reverse design’ of a molecular structure to yield an ionic liquid with the desired properties relies on detailed knowledge of how these properties emerge. However, classical structure-property relationships are often biased by confounding variables. Hence, it is important to consider targeted modifications, i.e. deliberate changes to the structure of an ionic liquid, changing as little variables at once as possible. Here we demonstrate how the approach can be used to disentangle contributions of flexibility, fluorination, and mass. Critically, we show that a significant part of the success of fluorination as a design element is in fact due to conformational flexibility; this aspect is commonly overlooked in conventional structure-property relationships.