Organic crystals with two-dimensional bending and manually twistable properties for flexible optical waveguides

Abstract

Most organic crystals are brittle, which greatly restricts their applications in flexible smart materials. Herein, we reported two multi-flexible organic crystals. One of them exhibits two-dimensional (2D) elasticity, while the other one exhibits dual plasticity and elasticity along different directions. Their brittle polymorphs were also prepared to establish the correlations of the structure-property of flexible organic crystals from the perspective of crystal engineering. These flexible crystals can be manually twisted without fracture. Therefore, it was verified that manually twisted crystals can also be prepared from 1D plastic and elastic crystals, which has not been reported before. Detailed crystallographic analyses, energy framework calculations and nanoindentation tests were used to reveal the mechanism of the multiple mechanical responses of these crystals. It was found that these properties can be ascribed to the large differences in strength and orientation between the intermolecular interactions, together with the unique molecular arrangement in the crystals. Finally, the application of these flexible crystalline materials in the field of the optical waveguide was developed.

Multistimulus-Responsive Cocrystals of Azobenzene Derivatives with Excellent Elastic Deformation Ability

“…Based on the above analysis, it can be said that the forceinduced elastic deformation of the AP cocrystal follows the following mechanism (Figure 5). When the crystal bends along the (010) plane under external force, the stacking structure based on π⋯π interactions along the c-axis could act like a spring, 44 buffering stress by expanding the outer arc and contracting the inner arc. Meanwhile, the rich and isotropic interactions between molecular chains could prevent a longdistance slip between molecules.…”

Flexible Organic Crystals for Dynamic Optical Transmission

“…By modulating various interactions such as π···π interactions, C–H···π interactions, hydrogen-bonding interactions, and halogen-bonding interactions, a plethora of mechanically flexible organic single crystals have been prepared. − Within this context, the combination of the flexibility of organic molecular crystals and their unique optoelectronic functionality opens up new avenues to be explored in the field of organic crystalline materials (Figure ). − …”

Dual control of passive light output direction by light and mechanical forces in elastic crystals

“…44,45 Moreover, Hao et al discovered two-dimensional (2D) bent and artificially twisted organic crystals for flexible optical waveguides. 46 Further, Hayashi et al reported two highly flexible organic crystals with optical waveguide properties. 47 Similarly, our group also studied passive light transmission from flexible crystals.…”