Integrating Urea‐Based Units Into Porphyrinic Covalent Organic Framework for Efficient Artemisinin Photosynthesis

Abstract

Abstract Artemisinin and its derivatives are the most efficacious treatment for malaria, and the artificial synthesis of artemisinin supplies a promising method to satisfy market demand. However, conventional artemisinin preparation via homogeneous photo/acid‐catalytic reactions usually suffers from the difficulty in recycling the photo/acid‐catalysts and treating waste acid. Consequently, it is still highly urgent for developing environment‐friendly and effective artificial preparation methods for artemisinin. Herein, a dual‐function covalent organic framework (COF), named Urea‐COF, has been synthesized from the condensation of meso‐tetra(p‐formylphenyl)porphyrin with 1,3‐bis(4‐aminophenyl)urea. UreaCOF exhibits a high surface area of 1732 m 2 g −1 with a large pore size of 3.1 nm, enabling a fast mass transport and high accessibility of urea groups. The urea groups as hydrogen bond donor catalytic sites bind strongly to the carboxylic acid to release H + , thereby increasing the acidity of the carboxylic acid. This, in combination with the exceptional capacity of porphyrin macrocycles to generate singlet oxygen, endows Urea‐COF with excellent heterogeneous photocatalytic activity toward tandem semisynthesis of artemisinin from dihydroartemisinic acid in a high conversion rate (99%) and yield (71%) without additional acid, superior to all the thus far reported homogeneous and heterogeneous photocatalytic systems.