A confinement-regulated (H 3 C-NH 3 ) + ion as a smallest dual-wheel rotator showing bisected rotation dynamics.

On the basis of variable-temperature single-crystal X-ray diffraction, rotational energy barrier analysis, variable-temperature/frequency dielectric response, and molecular dynamics simulations, here we report a new crystalline supramolecular rotor (CH 3 NH 3 )(18-crown-6)[CuCl 3 ], in which the (H 3 C-NH 3 ) + ion functions as a smallest dual-wheel rotator showing bisected rotation dynamics, while the host 18-crown-6 macrocycle behaves as a stator that is not strictly stationary. This study also provides a helpful insight into the dynamics of ubiquitous -CH 3 /-NH 3 groups confined in organic or organic-inorganic hybrid solids.