Formation of ionic co-crystals of amphoteric azoles directed by the ionic liquid co-former 1-ethyl-3-methylimidazolium acetate.

The ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate was utilized as a liquid-state crystallization agent to form ionic co-crystals using amphoteric azoles selected as model compounds for active pharmaceutical ingredients. Weakly acidic azoles crystallize the IL relatively quickly, while stronger acidic azoles undergo slower ion exchange with the IL to form salts.