Crystalline‐Phase‐Recognition‐Induced Domino Phase Transition and Luminescence Switching for Advanced Information Encryption

Abstract Herein, a new mechanism, namely, crystalline phase recognition (CPR), is proposed for the single‐crystal‐to‐single‐crystal (SCSC) transition of metal halides. Chiral β‐[Bmmim] 2 SbCl 5 (Bmmim=1‐butyl‐2,3‐methylimidazolium) can recognize achiral α‐[Bmmim] 2 SbCl 5 on the basis of a key–lock feature through intercontact of their single crystals, resulting in a domino phase transition (DPT). The concomitant photoluminescence (PL) switching enables observation of the DPT in situ. The liquid eutectic interface, stress–strain transfer, and feasible thermodynamics are key issues for the CPR. DFT calculations and PL measurements revealed that the optical absorption and emission of the isomers mainly originate from [SbCl 5 ] 2− anions. The structural effects (e.g., supramolecular interactions and [SbCl 5 ] 2− distortion) on the optical emission are clarified. As a novel type of stimuli response, the CPR‐induced DPT and luminescence switching exhibit potential for application in advanced time‐resolved information encryption.