Water-Driven Modulation of Multiresponsive Properties in Acylhydrazone-based Crystals

Abstract

A pyrene-substituted acylhydrazone (PyAc) crystal undergoes a water-driven transition from elasticity to thermoplastic bending. The hydrated crystal remains two-dimensional (2D) elastic when heated, but it becomes brittle and bent upon dehydration. While the hydrate crystal is non-photoresponsive, the anhydrous form exhibits photomechanical bending due to favorable E–Z photoisomerization. These distinct properties, governed by solvent channels, molecular packing, and non-covalent interactions, demonstrate PyAc's potential for smart actuators and photoswitchable devices.