Controlling the phase behavior and ion mobility of trialkylammonium-based protic ionic liquids: the role of asymmetry

The size, shape, and symmetry of cations and anions in ionic liquids determine the adjustable properties of these industrially relevant liquid salts. In this work, we show how the deliberately introduced asymmetry of cations can change and even control the phase behavior and rotational diffusion in protic ionic liquids. The method of choice here is solid-state NMR spectroscopy, which provides structural and dynamic information about the heterogeneous material. In addition, we show that the chosen trialkyl ammonium-based ionic liquids are excellent model systems for studying Coulomb-enhanced hydrogen bonding and anisotropic molecular motion.