Triggering the dynamics of a carbazole--[phenylene-diethynyl]-xylene rotor through a mechanically induced phase transition

A new rotor exhibits rich solvatomorphism behavior with eight X-ray structures obtained. A heterogeneous solid obtained by mechanical stress exhibited a dominant isotropic 2 H line shape at high temperatures. The motion occurs only in the amorphous component of this solid, with an E a of 7.4 kcal mol 1 and a low pre-exponential factor A of 6.22 10 10 s 1 , which indicates that the motion requires the distortion of the molecular axis. A crystalline molecular machine with several solid phases where only one is able to show intramolecular rotation.