Development of decimeter-length organic crystals that remain elastic, functional and machinable at extreme low temperature such as in liquid nitrogen (LN) environment is a great challenge. Herein, we report two novel elastic organic crystals 1 and 2 based on mono-benzene compounds. Crystals 1 are elastically bendable with the longest-to-date length (10 cm) and show better elastic bending ability at LN temperature compared to room temperature, while crystals 2 with centimeter-length decrease in elasticity in LN. Notably, crystals 1 are capable of cutting and stripping at the LN temperature. To the best of our knowledge, this is the first report on cryogenic machinability of organic crystals. By crystallographic analyses of 1 and 2, intermolecular interactions are disclosed to be responsible for their distinct crystal habits and cryogenic machinability. In addition, the post-stripping crystals 1 exhibit programmable optical waveguides that vary proportional to the crystal width and thus has the potential for applications as tunable wavelength modulators capable of real-time two-dimensional motion detection in cryogenic environments. This material not only advances the field of flexible organic crystals, but also opens up new possibilities for the development of smart materials that can be operated under extreme conditions.
