Insights into the Molecular Dynamics of Quasi-Spherical (Chloromethyl)triethylammonium Confined in a Weakly Bound Ionic Cocrystal.

Here, we report a weakly bound ionic cocrystal, (Et 3 NCH 2 Cl) 2 [ZnCl 4 ], which undergoes a reversible structural phase transition owing to the switched molecular dynamics of the quasi-spherical (Et 3 NCH 2 Cl) + cation from static to dynamic. Interestingly, a unique rolling and moving mechanism is uncovered for such a cation in the high-temperature phase, where its two methylene groups exhibit different kinetic energy barriers. This study provides a meaningful insight into the solid-state molecular dynamics of large-size quasi-spherical molecules that contain both a rigid core and flexible shell.