Functional flexible molecular crystals: intrinsic and mechanoresponsive properties

Recent interest in functional flexible molecular crystals has the potential to provide unique optoelectronic applications and stimuli-responsive chemistry. In crystal engineering, the designing of crystal structures from molecular structures has resulted in various functional molecular crystals for controlling photons, phonons, electrons, and magnons. The flexible behavior of molecular crystals, such as stress-induced response shape deformation, is another new feature recently realized by molecular and crystal structure design strategies. Such flexible molecular crystals with crystal features, such as intrinsic and mechano-responsive properties, have potential powerful applications, such as in wearable devices. Herein, the concept of functional flexible molecular crystals is highlighted, demonstrating the intrinsic properties of mechanical deformability and mechano-responsiveness induced by changes in crystal shape. Some outstanding examples of the light emission and electrical conduction properties of functional flexible molecular crystals are discussed. Key insight into similar future developments that offer intrinsic and mechanical stimuli-responsive behavior toward flexible molecular crystal devices is also provided.