Enzyme immobilization in a Ru(N^N)₃-modified covalent organic framework for photoenzymatic cascade catalysis

The co-immobilization of enzymes and metal catalysts addresses key challenges in chemo-enzymatic catalysis, leading to a more efficient and environmentally sustainable process. Central to this approach is the development of a solid support with large pore size and an efficient decoration method for both enzymes and metal catalysts. In this context, a mesoporous covalent organic framework is rationally designed as the porous solid carrier for co-immobilizing a Ru(N^N)₃-based photocatalyst, a Cp*Rh-based electron mediator, and an alcohol dehydrogenase. The integrated system catalyzes the Michael addition between 1-propanethiol and 1-penten-3-one to produce 1-(propylthio)pentan-3-one under visible light irradiation, which is further reduced to 1-(propylthio)pentan-3-ol with a photo-regenerated nicotinamide cofactor. This work presents a novel one-pot photobiocatalytic cascade system for synthesizing enantiomerically pure 1,3-mercaptoalkanols. The system showcases excellent performance in terms of yield and enantioselectivity, along with effective cofactor photo-regeneration, demonstrating a significant advancement in the field of chemo-enzymatic catalysis through enzyme and metal catalyst co-immobilization.