Cyclic host liquids for facile and high-yield synthesis of [2]rotaxanes.

We developed "cyclic host liquids (CHLs)" as a new type of solvent. The CHLs are a nonvolatile liquid over a wide temperature range, are biocompatible and recyclable, have high thermal stability, and are miscible with many organic solvents. Compared with typical complexation systems, the CHL system is extremely efficient for maintaining host-guest complexation because an additional solvent is not required.