Covalent organic frameworks (COFs) are crystalline porous organic materials connected by covalent bonds. They can be useful, e.g., in gas adsorption/separation, sensing, drug delivery, catalysis, or energy storage. COFs with oligo(phenylenevinylene) units, for example, could be useful for photocatalytic hydrogen evolution.
Longyu Li, Sichuan University, Chengdu, China, and colleagues have synthesized a series of linear oligo(phenylenevinylene)-based COFs and found that one with methoxy side groups showed good crystallinity and a high surface area, which led to improved hydrogen evolution performance. The team synthesized a linear oligo(phenylenevinylene)-based amine monomer, 1,4-bis[(4-aminophenyl)vinyl]benzene, and reacted it with different aldehydes to form imine lnkages between the buildign blocks. They used 1,3,5-triformylbenzene (TFB), 2,4,6-triformylresorcinol (TFR), and 1,3,5-triformylphloroglucinol (Tp) as the aldehyde building blocks.
Unfortunately, such long linear oligo(phenylenevinylene) building blocks can led to amorphous COFs. The researchers then introduced methoxy groups into these subunits as pore-directing “anchors”. They found that the resulting COFs were highly crystalline. The 1,3,5-triformylphloroglucinol derivative showed the best hydrogen evolution performance under visible light irradiation. According to the team, the work provides useful insights into the design of crystalline, oligo(phenylenevinylene)-based COFs.
- Linear oligo(phenylenevinylene)-based covalent organic frameworks,
Xingjiang Yu, Yuelin Zhong, Wenbo Dong, Longyu Li,
Chem. Commun. 2024.
https://doi.org/10.1039/d4cc04045g
