Probing the electronic structure of ether functionalised ionic liquids using X-ray photoelectron spectroscopy.

The charge distribution associated with individual components in functionalised ionic liquids (ILs) can be tuned by careful manipulation of the substituent groups incorporated into the ions. Here we use X-ray photoelectron spectroscopy to investigate the impact of substituent atoms on the electronic structure of similar imidazolium-based systems each paired with a common anion, [Tf2N]-. The experimental measurements revealed an unexpected variation in the charge density distribution within the IL cation when the oxygen atom in a poly-ether containing side chain is moved by just one atomic position. This surprising observation is supported by density functional theory calculations.