Design of higher valency in covalent organic frameworks
Cornelius Gropp1,2, Tianqiong Ma1,2, Nikita Hanikel1,2
1Department of Chemistry, University of California-Berkeley, Berkeley, CA 94720, USA.
Science (New York, N.Y.)
|October 23, 2020
Summary
Researchers developed a new method to create covalent organic frameworks (COFs) with higher valency, forming cube-like and rod-like structures. This expands the possibilities for designing advanced porous materials.
Area of Science:
- Materials Science
- Chemistry
- Nanotechnology
Background:
- Covalent organic frameworks (COFs) typically feature building units with valency 3 or 4.
- This limits the structural diversity and potential applications of COFs.
Purpose of the Study:
- To develop a novel strategy for synthesizing COFs with unprecedented higher valencies.
- To explore the creation of COFs with valency 8 (cubes) and "infinity" (rods).
Main Methods:
- Utilized 1,4-boronophenylphosphonic acid as a linker, featuring an isoelectronic boron and phosphorus combination.
- Condensed the linker to form porous polycubane structures (BP-COF-1 to 5) and rod-like structures (BP-COF-6).
- Characterized the resulting COFs using X-ray powder diffraction.
Main Results:
- Successfully synthesized COFs with valency 8, exhibiting a polycubane structure with cubes linked by phenyl groups.
- Prepared isoreticular forms (BP-COF-2 to 5) and large single crystals of a constitutionally isomeric COF (BP-COF-6) with rod units.
- Demonstrated the formation of novel COF architectures beyond traditional triangle and square/tetrahedron motifs.
Conclusions:
- The developed strategy enables the synthesis of COFs with significantly higher valencies (8 and "infinity").
- This breakthrough expands the valency regime in COF chemistry, opening new avenues for material design.
- The new COFs offer potential for advanced applications leveraging their unique structural properties.
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