Natural-based chiral task-specific deep eutectic solvents: A novel, effective tool for enantiodiscrimination in electroanalysis

Abstract

Deep Eutectic Solvents (DESs) offer advantages similar to ionic liquid (IL) ones, with easier and more sustainable synthesis; moreover, bio-based DESs often include chiral components, surprisingly underexploited. A proof of concept is now offered of the impressive potential of enantiopure chiral DESs as chiral media for enantioselective electroanalysis. Three chiral DESs, consisting of a molecular salt with bio-based chiral cation [NopolMIm]+ combined with three natural and/or low-cost partners (levulinic acid, glycerol and urea), are introduced and investigated as chiral voltammetry media. Significant potential differences are observed for the enantiomers of a model chiral probe, with a dramatic tuning depending on the achiral DES component, reaching an impressive ~0.5 V in the levulinic acid case (while less efficient appears [NopolMIm]+ as chiral additive in IL). With the same medium good enantiodiscrimination is also observed for aminoacid tryptophan, a quite different probe and of applicative interest. These findings can be considered as a remarkable step further in chiral electroanalysis as well as in the development of task-specific enantioselective media.