Irreversible Structural Phase Transition in [(9‐triptycylammonium) ([18]crown‐6)][Ni(dmit)₂]: Origin and Effects on Electrical and Magnetic Properties

The Front Cover shows a gear representing [18]crown-6 and a series of dominoes embodying [Ni(dmit)2]− anions (dmit2−=2-thioxo-1,3-dithiole-4,5-dithiolate). A crystal composed of 9-triptycylammonium, [18]crown-6, and [Ni(dmit)2]− exhibits an irreversible phase transition at 381 K involving the rotation of [18]crown-6 and rearrangement of [Ni(dmit)2]−. The rotation of the gear mirrors that of [18]crown-6, while the falling dominoes symbolize the reorientation of the [Ni(dmit)2]−. This significant phase transition causes a change in the magnetic system, increasing conductivity by four orders of magnitude. Notably, this is a very rare example of an irreversible phase transition driven by molecular rotation. These results pave the way for the development of innovative materials with irreversible phase transition characteristics. The artwork was designed by the first author, J. Manabe. More information can be found in the Research Article by S. Nishihara and co-workers.