Switchable Dielectric Phase Transition Triggered by Pendulum‐Like Motion in an Ionic Co‐crystal

Abstract Molecular‐based ionic co‐crystals, which have the merits of low‐cost/easy fabrication processes and flexible structure and functionality, have already exhibited tremendous potential in molecular memory switches and other electric devices. However, dipole (ON/OFF switching) triggering is a huge challenge. Here, we introduce a pendulum‐like dynamic strategy to induce the order–disorder transition of a co‐crystal [C 5 H 7 N 3 Cl] 3 [Sb 2 Br 9 ] (compound 1 ). Here, the anion and cation act as a stator and a pendulum‐like rotor (the source of the dielectric switch), respectively. The temperature‐dependent dielectric and differential scanning calorimetry (DSC) analyses reveal that 1 undergoes a reversible phase transition, which stems from the order–disorder transition of the cations. The thermal ON/OFF switchable motions make 1 a promising candidate to promote the development of bulk crystals as artificial intelligent dielectric materials. In addition, the pendulum‐like molecular dynamics and distinct arrangements of two coexisting ions with a notable offset effect promotes/hinders dipolar reorientation after dielectric transition and provides a rarely observed but fairly useful and feasible strategy for understanding and modulating the dipole motion in crystalline electrically polarizable materials.