A COMBINED MOLECULAR DYNAMICS AND X-RAY DIFFRACTION STUDY OF PROTIC IONIC LIQUID/WATER MIXTURES.

Ionic Liquids (ILs) have received considerable attention in recent years due to their potential as an environmentally friendly alternative to traditional organic solvents and due to a number of unique physicochemical properties that make them appropriate candidates for several scientific and technological applications, such as in catalysis and organic/inorganic synthesis. A subset of ILs are protic ionic liquids (PILs) which result from the proton transfer reaction between a Bronsted acid and a Bronsted base. The key properties that distinguish PILs from other ILs is the proton transfer from the acid to the base, leading to the presence of proton-donor and -acceptor sites, which can be used in PILs to build up a hydrogen-bonded network. The significance of the interaction between water and ILs has been well-recognized, given the fact that the ILs are hygroscopic and can absorb a significant amount of water from the atmosphere. Nevertheless, to date, our knowledge of the interaction between water and ILs remains somewhat empirical. In this respect, Molecular Dynamics (MD) simulations are a powerful tool for characterizing, at an atomistic level, the structural and dynamic properties of IL/water mixtures. However, in the case of disordered systems, such as ILs, the combination of theoretical and experimental techniques is essential to obtain reliable information. Among other approaches, the combined use of simulation methods and X-ray diffraction techniques has been shown to be particularly well-suited to provide a reliable description of liquid systems. In this poster we present our results of a combined Molecular Dynamics and X-ray diffraction investigation of mixtures of water with two PILs, namely Ethylammonium nitrate and n-Propyl ammonium nitrate. The focus will be on the changes of the structural properties of these PILs caused by the addition of water.