Unique Design Strategy for Dual Phase Transition That Successfully Validates Dual Switch Implementation in the...

Dual phase transition/switch materials are a critical cornerstone of information storage and sensing. However, they are difficult to design successfully, and compared with materials showing single-switchable phase transitions, the dual ones retain many challenges by far. Therefore, the significance of a general strategy is far greater than an accidental success. Here, an efficient strategy combining branchlike Et₃R and trunklike benzylamine analogues successfully validates dual-switch implementation in the dielectric materials. This inevitable success is based on our treelike analogue mentioned above in which amines with multiple branches can achieve a temperature-induced phase change. Exactly, (BCDA)₂ZnBr₄ [BCDA = benzyl-(2-chloroethyl)dimethylammonium] proves the regularity and undergoes two reversible phase transitions at 295.4 and 340.8 K, respectively. Variable-temperature single-crystal X-ray diffraction revealed that the generation of double phase transitions is caused by progressive changes of treelike BCDA⁺ as the temperature rises. Because the permittivity ε' of (BCDA)₂ZnBr₄ abruptly changed near the phase-transition temperatures, such physical properties make it have latent applicability. In short, the success of our strategy will inspire researches to discover more interesting dual phase transition/switch materials.