Manifold Mechanical Deformations of Organic Crystals with Optical Waveguiding and Polarization Rotation Functions

Abstract Although manifold flexible organic crystals with various kinds of mechanical properties have been reported recently, most of them only possess a single one that is either plastic or elastic. It is because different mechanical deformations require distinct packing structures and intermolecular interactions. Given that the organic crystal has an anisotropic physical nature it is possible but challenging to combine multiple mechanical deformation capabilities into one single crystal. Herein, based on a known organic molecule (Z)‐3‐(4‐(dimethylamino)phenyl)‐2‐phenylacrylonitrile (DPPC), a single crystal is obtained that exhibits three different mechanical properties, namely, elastic bending, thermoplastic bending and plastic twisting deformation. Notably, the unique DPPC crystal could serve as a quite good optical waveguiding medium in the straight, elastically bent and thermoplastic bent states. The crystals are also successfully applied for tuning the polarization direction of the light emitting from the crystal, and thus confirm the famous prediction that twisted crystals can tune polarization direction as liquid crystals do proposed by C. Mauguin in 1911. This study not only has scientific significance in guiding flexibility engineering but also provides a model of flexible organic crystals for multifunctional application in optical devices.