A Conformationally Stable Contorted Hexabenzoovalene.

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Contorted aromatic molecules are key building blocks for nonplanar graphene, fullerenes, and carbon nanotubes.
• Curvature in 2D aromatic systems is typically achieved using non-six-membered rings or cove/fjord regions.
• Synthesizing precisely contorted aromatic structures is challenging but crucial for advanced materials.

Purpose of the Study:

• To synthesize a novel polycyclic aromatic hydrocarbon (PAH) with significant contortion.
• To investigate the structural and conformational stability of the synthesized molecule.
• To explore the impact of contortion on the electronic properties of the π-system.

Main Methods:

• Synthesis of a polycyclic aromatic hydrocarbon (PAH) incorporating two peripheral triptycene units and six tert-butyl substituents.
• Single crystal X-ray diffraction to verify the molecular structure and contortion.
• High-temperature solution stability studies (up to 150°C).
• Selective removal of tert-butyl groups for comparative UV/Vis spectroscopy.

Main Results:

• A highly contorted PAH was successfully synthesized, featuring a unique arrangement of triptycene units.
• X-ray diffraction confirmed a significant contortion, with phenylene blades oriented nearly coplanar at a 16 Å separation.
• The contorted conformation demonstrated remarkable stability in solution, even at elevated temperatures (150°C).
• Selective dealkylation allowed for spectroscopic comparison of differently contorted versions of the same π-system.

Conclusions:

• The study presents a successful synthesis of a sterically driven, highly contorted PAH.
• The achieved molecular architecture exhibits exceptional thermal and conformational stability.
• The ability to tune contortion provides a pathway for investigating structure-property relationships in aromatic systems.