A Crystalline Three-Dimensional Covalent Organic Framework with Flexible Building Blocks
Xiaoling Liu1, Jian Li2,3, Bo Gui1
1Sauvage Center for Molecular Sciences, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Journal of the American Chemical Society
|January 22, 2021
Summary
Researchers developed a novel flexible three-dimensional covalent organic framework (3D COF) that exhibits reversible breathing motion upon vapor exposure. This breakthrough enables the creation of soft porous crystals with potential applications in smart materials.
Area of Science:
- Materials Science
- Crystallography
- Supramolecular Chemistry
Background:
- Synthesizing three-dimensional covalent organic frameworks (3D COFs) is challenging, typically relying on rigid building blocks.
- Utilizing flexible building blocks for 3D COF design presents significant hurdles in synthesis and structural determination.
Purpose of the Study:
- To explore the synthesis and structural characterization of 3D COFs constructed from flexible building blocks.
- To investigate the properties and potential applications of these novel flexible 3D COFs.
Main Methods:
- Designed and synthesized a novel 3D COF (FCOF-5) incorporating flexible C-O single bonds.
- Determined the crystal structure using 17 continuous rotation electron diffraction datasets, revealing a 6-fold interpenetrated pts topology.
- Fabricated a smart soft polymer composite film incorporating FCOF-5.
Main Results:
- Successfully synthesized a highly crystalline 3D COF, FCOF-5, from flexible building blocks.
- Confirmed the 6-fold interpenetrated pts topology of FCOF-5 through advanced crystallographic analysis.
- Demonstrated reversible vapor-induced expansion/contraction (breathing motion) in FCOF-5 and its polymer composite.
Conclusions:
- Flexible building blocks can be successfully employed to construct 3D COFs with unique properties.
- FCOF-5 exhibits significant breathing behavior, opening avenues for soft porous crystal development.
- The fabricated polymer composite displays reversible vapor-triggered shape transformation, highlighting potential in responsive materials.
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