A Cubic 3D Covalent Organic Framework with nbo Topology
Xue Wang1,2, Mounib Bahri3, Zhiwei Fu2
1Leverhulme Research Centre for Functional Materials Design, University of Liverpool, Liverpool, L7 3NY, U.K.
Journal of the American Chemical Society
|September 13, 2021
Summary
Researchers synthesized a novel porous three-dimensional covalent organic framework (3D COF) using square-planar cobalt(II) phthalocyanine units and spiroborate linkages. This new material, SPB-COF-DBA, exhibits high crystallinity and significant surface area.
Area of Science:
- Materials Science
- Chemistry
- Nanotechnology
Background:
- Three-dimensional (3D) covalent organic frameworks (COFs) are crucial materials with applications in various fields.
- Their synthesis often relies on high-connectivity building blocks or precise control over structural alignment.
- Achieving specific network topologies, like the nbo topology, remains a synthetic challenge.
Purpose of the Study:
- To develop a new synthetic strategy for constructing 3D COFs with the nbo topology.
- To utilize square-planar cobalt(II) phthalocyanine (PcCo) units and tetrahedral spiroborate (SPB) linkages for controlled framework assembly.
- To characterize the structural, crystalline, and porous properties of the resulting COF.
Main Methods:
- Employing a controlled alignment strategy using PcCo units and SPB linkages.
- Utilizing SPB linkages to enforce 90° dihedral angles between PcCo units, directing the formation of the nbo topology.
- Characterizing the synthesized material (SPB-COF-DBA) using powder X-ray diffraction (PXRD) and high-resolution transmission electron microscopy (HR-TEM).
Main Results:
- Successful synthesis of a porous 3D COF, SPB-COF-DBA, with the noninterpenetrated nbo topology.
- SPB-COF-DBA exhibits high crystallinity and long-range order, confirmed by 11 resolved diffraction peaks in PXRD.
- HR-TEM imaging validated the well-ordered crystal lattice.
- The material possesses cubic pores and permanent porosity, with a Brunauer-Emmett-Teller (BET) surface area of 1726 m² g⁻¹.
Conclusions:
- The controlled alignment strategy using specific building blocks is effective for constructing complex 3D COF topologies.
- SPB-COF-DBA represents a new, highly crystalline, and porous material with potential applications in areas requiring high surface area materials.
- The study demonstrates the successful integration of PcCo units into a robust 3D framework with defined porosity.
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