Micro- and mesoscopic structural features of a bio-based choline-amino acid ionic liquid

High energy X-ray diffraction data from a bio-based ionic liquid constituted by choline ([cho]) and an amino acid (AA), namely n-leucine ([nle]), are presented and described by means of an atomistic molecular dynamics simulation aiming at extracting detailed structural information at both microscopic and mesoscopic spatial scales. We find that similar to other previously studied analogous systems, a strong, hydrogen bonding driven, cation-anion correlation determines the microscopic structure. While other peculiar correlations exist in this [cho][nle] IL, the medium length alkyl tail of the AA leads to the development of a characteristic polar vs. apolar alternation, as a consequence of the alkyl tails segregation into domains, thus delivering the formation of an enhanced level of mesoscopic organization in this IL.