Shear Force Cropping Organic Molecular Crystals Based on Adaptive Hydrogen Bonding Network Reconstructions

Area of Science:

• Materials Science
• Crystallography
• Organic Chemistry

Background:

• Organic molecular crystals are typically brittle and prone to mechanical failure.
• Robust intermolecular forces and specific packing can lead to enhanced mechanical properties.

Purpose of the Study:

• To investigate the mechanical properties and processability of a chiral dithiolane derivative crystal (R-TAE).
• To explore the relationship between molecular design, crystal structure, and mechanical behavior.

Main Methods:

• Synthesis of R-TAE crystals using a three-solvent diffusion method.
• Mechanical testing including cutting, tearing, bending, and curling under shear forces.
• Analysis of crystal structure, crystallinity, and mechanical response before and after UV treatment.

Main Results:

• R-TAE crystals can be precisely cut into various shapes (semicircles, stars, etc.) using scissors while maintaining crystallinity.
• R-TAE exhibits reversible bending and curling, unlike brittle racemic crystals (RS-TAE).
• UV treatment enhances elastic modulus, indicating resistance to photoinduced stress.

Conclusions:

• The chiral R-TAE crystal possesses a unique, adaptable lattice due to symmetry-breaking effects, enabling exceptional mechanical properties and shape programming.
• High asymmetry facilitates energy dissipation and lattice slippage, preventing fracture.
• This research demonstrates a successful integration of top-down and bottom-up strategies for creating dynamic, processable crystals.