上海交通大学张帆团队报道了双酮吡咯激活的，窄带隙乙烯连接共价有机框架的动态缩合方法。相关研究成果于2024年11月12日发表在《德国应用化学》。

乙烯基单元本质上具有较小的空间、非极性和不饱和特性，是用于合成高性能半导体材料的众所周知的π桥。二维（2D）亚乙烯基连接的共价有机框架（COFs）代表了一类有前景的π共轭结构，然而，可逆形成碳-碳双键的可用单体范围仍然有限。

该研究以二甲基二酮吡咯并吡咯（DM-DPP）为关键单体，合成了一类新型的二维亚乙烯基连接的COFs。二酮吡咯并吡咯（DPP）的强电子缺失使其甲基取代基在L-脯氨酸和4-二甲氨基吡啶的水溶液中的共催化下容易被激活，与三位芳香醛进行动态缩合。

由此产生的COFs以重叠的AA堆叠排列结晶，并具有丰富、规则的纳米通道。它们稳健的乙烯基DPP连接模式增强了供体-π-受体共轭，并促进了沿垂直方向的π堆叠排列。

因此，合成的COFs表现出窄至1.02eV的带隙，并在可见光到近红外I（NIR-I）区域表现出优异的光捕获能力。此外，COFs可以通过简单的压力铸造转化为独立的薄颗粒，并在不同光源下表现出优异的光热响应和循环稳定性。

附：英文原文

Title: Diketopyrrolopyrrole-Activated Dynamic Condensation Approach to Narrow-Band Gap Vinylene-Linked Covalent Organic Frameworks

Author: Zixing Zhang, Fancheng Meng, Xu Chi, Yang Jiao, Bai Xue, Xiaomeng Li, Fan Zhang

Issue&Volume: 2024-11-12

Abstract: Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well-known π-bridge used in the synthesis of high-performance semiconducting materials. Two-dimensional (2D) vinylene-linked covalent organic frameworks (COFs) represent a promising class of π-conjugated structures, however, the range of available monomers for the reversible formation of carbon-carbon double bonds remains limited. In this study, a new class of 2D vinylene-linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM-DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L-proline and 4-dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP-linking mode enhanced donor-π-acceptor conjugation and promoted π-stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light-harvesting capability across the visible to near-infrared I (NIR-I) regions. Furthermore, the COFs could be converted into free-standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

DOI: 10.1002/anie.202417805

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202417805