A Redox-Gated Slow-Fast-Stop Molecular Rotor

A pentiptycene-derived p-phenylenediamine mimics a molecular double-rotor system that displays redox-dependent rotation rates for the amino rotors about the pentiptycene-amine C–N bond. The rotation is accelerated in the radical cation state but stopped in the di(radical cation) state. Electronic interplay of the two rotors is also discussed.