  A new class of deep eutectic solvents are presented where one component of
the system is inherently volatile, enabling a premeditated, auto-destructive
capability which leads inexorably to a series of novel crystal structures.
These volatile deep eutectic solvents are easily-formed liquids with a greatly
depressed melting point and exhibit all of the physical characteristics of
classical deep eutectic solvents, with the exception that the hydrogen-bond
donor component is volatile when exposed to the atmosphere at room temperature.
We demonstrate the effectiveness of this concept through the exquisite control
of pharmaceutical polymorphism, among which is a more efficacious form of
acetaminophen, which can be formed spontaneously for the first time at room
temperature.
