scheme1
![Catalyst-free solid-state cross-linking of covalent organic frameworks in confined space](https://image.oaes.cc/10293532-4bf9-4195-8176-05fcb71e603e/cs3045.scheme.1.jpg)
Scheme 1. Historical development of acetylenic polymers. (A) Previously reported acetylenic polymers and corresponding structures; (B) This study presents the synthesis of 2D COFs and the proposed mechanism of transforming them into crystalline CL-COFs via solid-state cross-linking in confined spaces. COFs: Covalent organic frameworks; CL-COFs: crystalline cross-linked covalent organic frameworks.