East China Institute of Technology reconstructs covalent organic framework materials

Recently, the international authoritative academic journal "Nature" online reported the breakthrough progress made by Professor Zhu Weihong and Academician Tian He from the School of Chemistry and Molecular Engineering of East China University of Science and Technology in the research on the construction of covalent organic framework materials based on dynamic chemistry

The core challenge of covalent assembly of crystallization dilemma frameworks

According to the leader of the research team, COF material is an emerging crystalline porous material.

Dynamic covalent chemistry is the scientific basis for the directional design of COF materials, which endows the covalent assembly process with error correction ability and is the key to simultaneously achieve crystallinity and stability

Framework refactoring for more precise and stronger covalent connection

The research team draws on the concepts of supramolecular chemistry nanoconfined reaction and dynamic covalent chemistry, cleverly separates framework covalent assembly and irreversible covalent bonds, and proposes a synthesis strategy of "reconstructing covalent organic frameworks": using reversible covalent covalent valence bonds, "pre-assemble" organic primitives into a crystalline framework, and then perform "confined reconstruction" after synthesis, thereby realizing the efficient preparation and large-scale production of high-stability crystalline COFs under conventional synthesis conditions

In practice, the researchers used urea bonds with strong directionality and high reversibility as "covalent ropes" to pre-assemble molecular elements into a highly crystalline COF framework, and then reuse water at a higher reaction temperature.

Better performance, better material, better performance

According to the leader of the research team, the crystallinity and porosity of the RC-COF material prepared by the reconstruction method have been significantly improved compared with the COF material prepared by the traditional direct polymerization method: the specific surface area is increased by up to 4.

　　High crystallinity not only brings higher specific surface area and porosity, but also endows the material with more superior photogenerated carrier formation and transport capabilities

　　According to another introduction, the innovative concept of this work was inspired by the concept of "turning a cocoon into a butterfly" in Chinese excellent traditional culture - pre-assembled into a crystalline metastable covalent framework through weak reversible covalent bonds, and then through dynamic The chemical, nanoconfinement reaction forms a new and more stable framework, similar to the process of the butterfly's transformation from a larva to a butterfly