Crystalline Dioxin-Linked Covalent Organic Frameworks from Irreversible Reactions

Area of Science:

• Materials Science
• Organic Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are crystalline porous polymers with tunable properties.
• Traditional COF synthesis often relies on reversible condensation reactions, limiting their chemical stability.
• Developing robust COFs with accessible functionalities is crucial for advanced applications.

Purpose of the Study:

• To synthesize novel 2D covalent organic frameworks (COFs) using irreversible reactions.
• To investigate the chemical stability and porosity of the synthesized COFs.
• To demonstrate the potential for post-synthetic modification of these robust frameworks.

Main Methods:

• Utilized nucleophilic aromatic substitution (S_NAr) reactions between triangular 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and linear tetrafluorophthalonitrile (TFPN) or 2,3,5,6-tetrafluoro-4-pyridinecarbonitrile (TFPC).
• Formed crystalline 2D COFs, COF-316 and COF-318, linked by 1,4-dioxin bonds.
• Performed post-synthetic modifications on COF-316 under harsh conditions.

Main Results:

• Successfully synthesized COF-316 and COF-318 via irreversible S_NAr reactions.
• The resulting 1,4-dioxin linked COFs exhibit high chemical stability in acidic and basic conditions.
• Demonstrated permanent porosity and the feasibility of post-synthetic modifications for introducing new functionalities.

Conclusions:

• Irreversible S_NAr reactions provide a robust pathway for synthesizing stable COFs.
• COF-316 and COF-318 possess inherent chemical stability and permanent porosity.
• These novel COFs offer a versatile platform for advanced materials design and applications through post-synthetic functionalization.