上海交通大学张帆团队报道了将杂原子嵌入制备具有等电子结构乙烯键连接的共价有机框架用于光催化。相关研究成果于2021年11月23日发表在国际顶尖学术期刊《德国应用化学》。

在高分子材料的主链中嵌入杂原子已成为调整其结构和改善其性能的有效工具。然而，由于相对苛刻的杂原子掺杂条件，在共价有机框架（COFs）中很少被探索。

该文中，通过三甲基取代的吡喃盐与三位芳香醛的羟醛缩合，制备了具有乙烯基键的二维含氧鎓的COF，其通过在氨处理下用氮原子原位替换氧鎓离子进一步转化为中性吡啶芯COFs。两个杂原子嵌入的COFs在概念上彼此等电子，具有相似的几何结构但不同的电子结构，使得它们能够催化可见光促进的多组分合成具有良好再循环性的三取代吡啶衍生物。

附：英文原文

Title: Heteroatom-Embedded Approach to Vinylene-Linked Covalent Organic Frameworks with Isoelectronic Structures for Photoredox Catalysis

Author: Shuai Bi, Zixing Zhang, Fancheng Meng, Dongqing Wu, Jie-Sheng Chen, Fan Zhang

Issue&Volume: 2021-11-23

Abstract: Embedding heteroatoms into the main backbones of polymeric materials has become an efficient tool for tailoring their structures and improving their properties. However, owing to comparatively harsh heteroatom-doping conditions, this has rarely been explored in covalent organic frameworks (COFs). Herein,  upon Aldol condensation of a trimethyl-substituted pyrylium salt with a tritopic aromatic aldehyde, a two-dimensional oxonium-embedded COF with vinylene linkages was achieved, which was further converted to a neutral pyridine-cored COF by in situ replacement of oxonium ions with nitrogen atoms under ammonia treatment. The two heteroatom-embedded COFs are conceptually isoelectronic with each other, featuring similar geometric structures but different electronic structures, rendering them capable of catalyzing the visible-light-promoted multi-component synthesis of tri-substituted pyridine derivatives with good recyclability.

DOI: 10.1002/anie.202111627

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202111627