Enzyme Immobilization in Porphyrinic Covalent Organic Frameworks for Photoenzymatic Asymmetric Catalysis

Integrating photocatalysis and biocatalysis to fabricate photobiocatalysts for asymmetric catalysis is of great significance but remains challenging. In this work, we build a photoenzymatic platform for asymmetric catalysis using rationally designed photocatalytic porphyrinic covalent organic frameworks (COFs) as mesoporous solid carriers to immobilize wheat germ lipase (WGL). The formed WGL@COFs photobiocatalysts show high enzymatic activity and good operational stability. Attributed to the proximity effect of photocatalysts and enzymes in one system, WGL@COFs exhibit good performance and reusability for an enantioselective Mannich reaction under visible light irradiation. Notably, this asymmetric reaction with the formation of C(sp3)–C(sp3) bonds cannot be achieved by WGL or COFs independently. Furthermore, various characterization techniques unveil the catalytic mechanism (singlet oxygen as the main pathway of asymmetric catalysis). This work creates a general and efficient strategy using COFs as photocatalytic platforms for enzyme immobilization to fabricate photobiocatalysts that realize highly efficient photoenzymatic asymmetric catalysis.