Click To Stack: Shape-Assisted Self-Assembly of Unflattened Macrocycles into Waveguiding Elastic Crystals.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Precise control over intermolecular interactions is crucial for designing molecular crystals.
• Existing methods for constructing complex molecular assemblies can be challenging and lack systematic modification pathways.

Purpose of the Study:

• To develop a facile and systematic strategy for constructing and modifying tetraarene-fused cyclooctatetraenes.
• To investigate the self-assembly behavior and structural properties of these novel molecular building blocks.
• To explore the potential applications of the resulting anisotropic crystalline materials.

Main Methods:

• A 'click-to-stack' strategy was employed for molecular synthesis.
• Single-crystal X-ray crystallography was used to determine the precise molecular packing.
• Computational studies were performed to understand intermolecular forces and stacking interactions.
• Modification with alkoxy groups was used to influence crystal morphology and properties.

Main Results:

• Saddle-shaped tetraarene-fused cyclooctatetraenes self-assemble into one-dimensional columns via van der Waals interactions.
• Fully eclipsed π-π stacking was observed, driven by molecular shape complementarity.
• Antiparallel alignment of coaxial cable-like assemblies formed centimeter-long, voidless, and mechanically durable crystals.
• The crystalline rods exhibited optical waveguiding properties and elasticity.

Conclusions:

• The click-to-stack strategy provides precise control over the construction of highly anisotropic molecular crystals.
• The unique self-assembly behavior driven by weak interactions and shape complementarity leads to robust crystalline materials.
• These materials demonstrate practical utility in applications such as optical waveguiding, highlighting the potential of ordered molecular assemblies.