Mechanochemical Cyclotrimerization: A Versatile Tool to Covalent Organic Frameworks with Tunable Stacking Mode

Area of Science:

• Materials Science
• Organic Chemistry
• Mechanochemistry

Background:

• Traditional nitrile cyclotrimerization methods face challenges with solubility and carbonization.
• Developing efficient, solid-state synthetic routes for triazine-based materials is crucial.

Purpose of the Study:

• To introduce a novel mechanochemical approach for nitrile cyclotrimerization.
• To synthesize triazine-containing molecules and covalent triazine frameworks (CTFs) efficiently.
• To demonstrate control over CTF structure and material properties.

Main Methods:

• Solid-state mechanochemical cyclotrimerization using a mixer ball mill.
• Reaction of 4-Methylbenzonitrile to form Tris(4-methylphenyl)-1,3,5-triazine.
• Reaction of 1,4-Dicyanobenzene to synthesize covalent triazine framework (CTF-1).

Main Results:

• Quantitative synthesis of Tris(4-methylphenyl)-1,3,5-triazine in 90 minutes.
• Rapid synthesis of porous (650 m²/g) and crystalline CTF-1.
• Demonstrated control over CTF stacking conformations (AA and AB) by adjusting mechanical energy.
• Successful synthesis of various CTFs, showcasing substrate scope and versatility.

Conclusions:

• Mechanochemical cyclotrimerization of nitriles is a facile and efficient strategy for synthesizing triazine materials.
• This solid-state method overcomes limitations of traditional approaches, offering tunable material properties.
• The developed method provides a versatile platform for creating diverse CTFs with controlled structures.