Ferroelastics, the mechanism analogous to ferroelectrics and ferromagnets, has broad application prospects in reconcilable grating, tunable acoustic filters and optical domain wall memories. However, the contingency of symmetry
changes during the phase transition brings a great challenge to construct ferroelastic materials. Fu and coworkers successfully designed two hybrid materials by crystallographic engineering. The intermolecular H-bonds simultaneously achieved dimensional regulation and an increase in phase transition temperature. Furthermore, the switchable ferroelastic domains were observed by a polarizing microscope. This photochromic ferroelastic might be a potential candidate in the fields of mechanical switches, shape memory and reconcilable grating (see the article on page 3687).

Ferroelastics, the mechanism analogous to ferroelectrics and ferromagnets, has broad application prospects in reconcilable grating, tunable acoustic filters and optical domain wall memories. However, the contingency of symmetry
changes during the phase transition brings a great challenge to construct ferroelastic materials. Fu and coworkers successfully designed two hybrid materials by crystallographic engineering. The intermolecular H-bonds simultaneously achieved dimensional regulation and an increase in phase transition temperature. Furthermore, the switchable ferroelastic domains were observed by a polarizing microscope. This photochromic ferroelastic might be a potential candidate in the fields of mechanical switches, shape memory and reconcilable grating (see the article on page 3687).