Accordion‐Like Motion in Electrochemically Switchable Crown Ether/Ammonium Oligorotaxanes
H.V. Schröder, F. Stein, J.M. Wollschläger, S. Sobottka, M.Gaedke, B. Sarkar, C.A. Schalley – 2019
In conclusion, a novel class of electrochemically controlled oligorotaxanes that can reversibly generate an accordion‐like motion is reported. The freedom of translation of the TTF‐decorated macrocycles is crucial to enable intramolecular mixed‐valence or radical‐cation interactions between the TTF units of the wheels, which are only observed for R2 and R3. An oxidation of both oligorotaxanes leads to these attractive wheel–wheel interactions. Further oxidation to the fully oxidized states (TTF.+→TTF2+) creates repulsive Coulombic forces and leads to a maximization of the inter‐wheel distances. This novel electrochemically controlled accordion‐like motion (contraction/expansion) is highly promising for the design of new smart materials and the construction and operation of stimuli‐responsive nanomachines, such as piston rotaxane motors.