Intermolecular Interactions in Mixed Choline Acetate and Maleic Acid Systems

Mixed systems based on ionic liquids are promising innovative solvents due to their properties, which are strictly connected to the interactions that arise among the components. The present work investigates the intermolecular interactions of a mixed choline acetate and maleic acid system and their modifications with increasing acid content. MM/DFT calculations provided indications about the possible geometric configurations of the systems while Non-Covalent Interaction analysis was useful to describe and distinguish secondary interactions. The number of available configurations decreases at high acid concentration. Moreover, intramolecular hydrogen bonding was observed in all configurations except that in the most stable one of the lowest acid content mixture. Concomitantly, far-infrared spectroscopy was used to investigate intermolecular interactions and provided support to the computational results.