The formation of two-component supramolecular polymers can lead to high supramolecular designability by a combination of different kinds of components in addition to the development of thermal and physical properties. These features are suitable for screening mechanical properties of low molecular crystals. Herein, we demonstrate ferroelasticity in a co-crystal of pimelic acid and 1,2-di­(4-pyridyl)­ethane, which form a one-dimensional supramolecular polymer by hydrogen bonds in the single crystalline state. The crystal showed a permanent biased ferroelastic hysteresis loop as a mixture of ferroelasticity and superelasticity, which is attributable to multiple crystallographically independent molecules.

Reversible and versatile plastic deformation of crystalline solids over elastic limits is achieved in a diffusionless manner on the basis of a mechanically induced structural transition. Specific alloys, known as shape-memory alloys (SMAs), show spontaneous shape recovery based on such deformability. Molecular single crystals can also exhibit superelasticity, but their bending behavior has been limited to a specific bending angle toward a specific bending direction, referred to as strict deformability, due to the anisotropic nature of molecules and single crystals. Although a versatile deformation with variable bending angle in a single crystal showing spontaneous strain, i.e. ferroelasticity, has been achieved by the multiple twinning mechanism, superelastic deformation by the mechanism has not been observed. Here we demonstrate versatile superelastic deformation in a 1,3,5-trichlorobenzene crystal by the mechanism. Our findings demonstrate the possible development of superelastic molecular materials with almost free deformability through the multiple-discrete-mode twinning mechanism.