Tightening or loosening a pH-sensitive double-lasso molecular machine readily synthesized from an ends-activated [c2]daisy chain

The ready synthesis of a new double-lasso molecular machine from an ends-activated [c2]daisy chain has been achieved. This original architecture consists of a unique double-lasso structure, where the two macrocycles can slide along the threaded pseudo-macrocycle upon variation of pH. The interlocked structure allows for two very different conformations: at low pH, it has a loose conformation with a big cavity. The interlocked molecule thus behaves like a controllable jump rope. After deprotonation, the molecule adopts a helical-type tightened conformation with a shrunken cavity. In this conformation, no jump rope movement is possible due to the tightened lasso.