Neutron diffraction will be used first to measure the pure IL structure of the acetate and octanoate EthylMethylimidazolium (Emim). From this comparison, the effect of the anionic alkyl chain length on the aprotic IL structure will be explored. Based on these measurements, structure and interaction of the acetate and octanoate Emim will be then compared to those of the imidazolium octanoate based protic ionic liquid to enhance the understanding of structure and interaction changes from protic to aprotic cation on solution. Secondly, the structure and interaction changes in presence of solvent (xsolvent = 75) will be investigated for the acetate and octanoate. In order to probe the specific interactions and facilitate the analysis of the data obtained, hydrogen-deuterium isotopic substitution on the ionic liquid anion as well as solvents will be used. The deuteriated and protiated ionic liquids have been synthesised at QUB. For each system, seven experiments will be performed for each solute-ionic liquid combination.