Fabricating Elastic Molecular Crystals with Enhanced Mechanical Durability through Molecular Engineering

The exploration of elastic organic molecular crystals has significant implications for modulating the mechanical properties of crystalline materials and their practical applications. However, existing research has largely concentrated on the packing regulation of planar molecules, imposing inherent constraints on achievable mechanical properties. Herein, one flexible molecular crystal constructed by purely covalent non-planar twisted conformation with enhanced elastic properties demonstrates unprecedented mechanical capabilities including extensive bending, weight-lifting capacity of 4500 times its mass, and so on. Notably, slender and anisotropic crystals show considerable promise for waveguides and birefringence optical components including sufficiently low optical loss coefficients in the near-infrared region and birefringence coefficient (Δn) comparable to commercial ionic crystals. This work provides innovative strategies for designing flexible crystals and advances the practical frontiers of functionalized crystalline materials.