Researchers developed three donor-acceptor covalent organic frameworks to improve Fenton-like water purification, according to a study published in Nature Communications. The work investigated how regioisomerism alters framework electronic structures to generate singlet oxygen through peroxymonosulfate activation.
The team constructed three constitutionally isomeric frameworks—TF-22Bpy, TA-22Bpy, and TA-33Bpy—by altering the positions of imine and pyridine nitrogen atoms in the molecular skeleton. Testing demonstrated that TA-33Bpy showed the highest catalytic performance for peroxymonosulfate activation, producing an observed rate constant of 0.165 min⁻¹. That rate exceeded the 0.052 min⁻¹ constant of TA-22Bpy by a factor of 3.2 and surpassed the 0.013 min⁻¹ rate of TF-22Bpy by a factor of 12.7.
Laboratory analysis showed that direct contact between peroxymonosulfate and the covalent organic framework induces charge polarization across the donor-acceptor matrix. This shift forms localized electron-deficient and electron-enriched domains that facilitate the coupled redox reactions required to selectively produce singlet oxygen.
Chengming Xiao, Mengjia He, Wenbo Yang, Yuxin Tian, Junwen Qi, Zhigao Zhu, Yujun Zhou, Yue Yang, and Jiansheng Li at the Nanjing University of Science & Technology conducted the study alongside Xiaoguang Duan and Shaobin Wang at Adelaide University. Funding came from the National Natural Science Foundation of China under grant 22276096 and the Postgraduate Research & Practice Innovation Program of Jiangsu Province under grant KYCX25_0807.
