We also calculated some statistical descriptors on structural fluctuations and rotational features of 2C 18 @OPP for quantitative analysis (Table ). As mentioned above, C 18 is sometimes adsorbed to the inner side of the loop at relatively high temperatures. The percentage of these tilted conformations in the overall trajectory is given as p out , and these snapshots were not included in statistical analysis because 2C 18 @OPP has lost its rotational characteristics in these cases. At relatively low temperature, the C 18 is always quasi-parallel to the loop which it resides and lies at a con-center position in loop during the simulation process, as indicated by the almost negligible α SD and d SD . The changing trends of these structural descriptors with respect to temperature clearly show that increasing temperature significantly reduces the stability of the supramolecular nanorotator 2C 18 @OPP. The average unsigned rotational velocity (ω) is a key metric for comparing the overall rotational speed of C 18 in OPP at different temperatures. It has been observed that the ω value is strongly dependent on temperature, that is, higher temperature usually drives C 18 to rotate faster because of larger atomic average kinetic energy (Table ). However, the increase of ω by temperature change from 300 to 400 K is not very prominent, which is apparently because excessive atomic kinetic energies also lead to the obvious disorder of atomic motion of C 18 and destroys its rotor characteristics to a certain extent. The average number of periodic rotations per second of C 18 , namely rotational frequency (f) calculated by the formula f = ω/(2π), indicates that 2C 18 @OPP can be regarded as an ultrafast rotator in sub-THz regime.