Porous Crystalline Olefin-Linked Covalent Organic Frameworks
Hao Lyu1, Christian S Diercks1, Chenhui Zhu2
1Department of Chemistry , University of California-Berkeley ; Materials Sciences Division, Lawrence Berkeley National Laboratory; and Kavli Energy NanoSciences Institute, Berkeley , California 94720 , United States.
Journal of the American Chemical Society
|April 25, 2019
Summary
Researchers developed COF-701, the first unsubstituted olefin-linked covalent organic framework. This robust material exhibits porosity and retains catalytic activity after immobilizing a Lewis acid, showing promise for chemical applications.
Area of Science:
- Materials Science
- Organic Chemistry
- Catalysis
Background:
- Covalent organic frameworks (COFs) offer tunable properties for various applications.
- Developing robust COFs with specific linkages is crucial for advanced material design.
- Unsubstituted olefin linkages present a unique structural motif for enhanced stability.
Purpose of the Study:
- To synthesize and characterize the first unsubstituted olefin-linked covalent organic framework (COF-701).
- To evaluate the chemical robustness and porosity of the novel COF.
- To demonstrate the catalytic potential of the COF by immobilizing a Lewis acid.
Main Methods:
- Aldol condensation reaction between 2,4,6-trimethyl-1,3,5-triazine (TMT) and 4,4'-biphenyldicarbaldehyde (BPDA).
- Fourier transform infrared (FT-IR) spectroscopy and solid-state 13C cross-polarization magic angle spinning (CP-MAS) NMR spectroscopy for structural confirmation.
- Porosity measurements and chemical stability tests under acidic and basic conditions.
- Immobilization of Boron trifluoride diethyl etherate (BF3·OEt2) and catalytic testing in a Diels-Alder reaction.
Main Results:
- Successful synthesis of COF-701, featuring unsubstituted olefin linkages (-CH=CH-).
- COF-701 exhibits high porosity (1715 m2 g-1) and exceptional chemical robustness in strong acidic and basic media.
- Immobilized BF3·OEt2 within COF-701 (BF3⊂COF-701) retained catalytic activity in a benchmark Diels-Alder reaction.
Conclusions:
- COF-701 represents a significant advancement as the first unsubstituted olefin-linked COF.
- The inherent stability of the olefin linkage imparts remarkable chemical robustness to the framework.
- The porous structure and retained catalytic activity of BF3⊂COF-701 highlight its potential as a reusable heterogeneous catalyst.
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