Li Shengxu,Xu Shunqi,Lin En,Wang Tonghai,Yang Haoyong,Han Junyi,Zhao Yuxiang,Xue Qunji,Samorì Paolo,Zhang Zhenjie,Zhang Tao
sp 2 -carbon-linked covalent organic frameworks ( sp 2 c-COFs) are crystalline porous polymers with repeat organic units linked by sp 2 carbons, and have attracted increasing interest due to their robust skeleton and tunable semiconducting properties. Single-crystalline sp 2 c-COFs with well-defined structures can represent an ideal platform for investigating fundamental physics properties and device performance. However, the robust olefin bonds inhibit the reversible-reaction-based crystal self-correction, thus yielding polycrystalline or amorphous polymers. Here we report an imine-to-olefin transformation strategy to form single-crystal sp 2 c-COFs. The isolated single crystals display rectangular nanotube-like domains with sizes up to approximately 24 μm × 0.8 μm × 0.8 μm, and permanent pore distribution around 1.1 nm. The highly conjugated olefin linkage endows the crystals with enhanced electronic connectivity which determines a remarkable room-temperature metal-free ferromagnetism (8.6 × 10 −3 emu g −1 ). Our protocol is robust and generally applicable for the synthesis of single-crystalline sp 2 c-COFs for future spin-electron devices.
A new strategy for nereistoxin-related insecticide, cartap, detection in foodstuff and the environment is of great importance due to its poisoning of human beings through direct exposure or via biomagnification . Herein, a highly planar conjugated sp 2 carbon-connected COF (F-C sp 2 -TT) was synthesized via Knoevenagel condensation reaction followed by the post-modification to develop a new platform for cartap visual detection in agricultural and food samples. The synergistic effect of highly planar conjugation and dense functional groups in the opened framework endowed F-C sp 2 -TT with a high-precision luminescence sensing performance. Meanwhile, the exquisitely designed F-C sp 2 -TT presented robust chemical stability, radiation stability, and good reproducibility. Benefiting from these advantages, high-precision luminescent F-C sp 2 -TT achieves a low detection limit of 0.51 μg/L to cartap over the range of 1–300 μg/L ( R 2 =0.9938), and the recoveries percentage in food products was calculated as 95.90%− 119.3%. More significantly, the smartphone-based high-precision platform by F-C sp 2 -TT was established and successfully applied to portable monitoring of cartap and water content. Therefore, our work revealed the enormous potential of C sp 2 -connected COF, which opened a new situation for insecticide detection.
危险品化学品经营许可证（带存储）