Chi Xu, Zhang Zixing, Li Mengqi, Jiao Yang, Li Xiaomeng, Meng Fancheng, Xue Bai, Wu Dongqing, Zhang Fan
School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
Angew Chem Int Ed Engl. 2025 Feb 10;64(7):e202418895. doi: 10.1002/anie.202418895. Epub 2024 Nov 11.
Polycyclic aromatic hydrocarbons (PAHs) hold the predominant role either as individual molecules or building blocks in the field of organic semiconductors or nanocarbons. Connecting PAHs via sp-carbon bridges to form high-crystalline π-extended structures is highly desired not only for enlarging the regimes of two-dimensional materials but also for achieving exceptional properties/functions. In this work, we developed 5,10-dimethyl-4,9-diazapyrene as a key monomer, whose two methyl groups at the positions adjacent to nitrogen atoms, can helpfully increase the solubility, and serve as the active connection sites. In the presence of organic acids, this monomer enables smoothly conducting Knoevenagel condensation to form two vinylene-linked PAH-cored COFs, which show high-crystalline honeycomb structures with large surface areas up to 1238 m g. Owing to the direct connection mode of PAH building blocks with vinylene, the as-prepared COFs possess spatially extended π-conjugation and substantial semiconducting properties. Consequently, their visible-light photocatalysis with exceptional activity and durability was manifested to generate HO up to 3820 μmol g h in pure water, and even 17080 μmol g h using benzyl alcohol as a hole sacrificial agent.
多环芳烃（PAHs）在有机半导体或纳米碳领域中，无论是作为单个分子还是构建单元都起着主导作用。通过sp-碳桥连接多环芳烃以形成高结晶度的π-扩展结构，不仅对于扩大二维材料的范围很有必要，而且对于实现优异的性能/功能也很有必要。在这项工作中，我们开发了5,10-二甲基-4,9-二氮杂芘作为关键单体，其在与氮原子相邻位置的两个甲基有助于提高溶解度，并作为活性连接位点。在有机酸存在下，该单体能够顺利进行Knoevenagel缩合反应，形成两个亚乙烯基连接的以多环芳烃为核心的共价有机框架（COFs），它们呈现出具有高达1238 m² g⁻¹大表面积的高结晶度蜂窝状结构。由于多环芳烃构建单元与亚乙烯基的直接连接方式，所制备的共价有机框架具有空间扩展的π共轭和显著的半导体性质。因此，它们表现出具有优异活性和耐久性的可见光光催化性能，在纯水中产生高达3820 μmol g⁻¹ h⁻¹的羟基自由基（HO·），使用苯甲醇作为空穴牺牲剂时甚至可达17080 μmol g⁻¹ h⁻¹ 。
