Role of Solid-Solid Transitions of Choline-Halides on Deep Eutectic Solvents

Deep eutectic solvents (DESs) are a cheap, renewable, and versatile cousin of ionic liquids. DESs form via the eutectic point depression between binary mixtures of suitable constituent compounds. Choline halides are the most common HBA constituent in most DESs. Complete phase diagrams reveal insights to the formation of DESs. Choline-halide based DESs show melting transitions around the solid-solid (s→s) transition temperature of ChX + HBD compounds. This effect suggests deeper ties to the phase behavior, as this ultimately dictates the eutectic composition and temperature of resulting DES combinations utilizing choline halides as a constituent.