Asymmetric C-H Hydroxylation via Photobiocatalytic Cascades: Metal-Coordinated Covalent Organic Frameworks for In-Situ H2O2 Generation and Enzymatic Consumption

Unspecific peroxygenases (UPOs) enable the selective hydroxylation of inert C–H bonds using H 2 O 2 under mild conditions. However, their practical application is fundamentally limited by oxidative deactivation at elevated H 2 O 2 concentrations. Herein, a highly synergistic photobiocatalytic system is constructed by covalently immobilizing UPOs onto a Rh-complex-coordinated covalent organic framework (COF) to facilitate the in-situ generation of H 2 O 2 and sequential enzymatic utilization. Specifically, a COF featuring a pyridinic imine structure (COF PyIm ) is designed to precisely anchor Rh(III) complexes. Compared with its bipyridine-structured analog (COF Bpy ), COF PyIm provides more coordination sites and a shorter electron-transfer distance. Consequently, the photocatalytic H 2 O 2 synthesis rate reached 22.17   mM·g -1 ·h -1 , representing a performance improvement of approximately 40%. This enhancement is attributed to the optimized pyridine–imine coordination microenvironment, which promotes charge separation and electron transfer. Subsequently, UPO from Agrocybe aegerita ( Aae UPO) is covalently immobilized onto COF PyIm to yield Aae UPO@Rh-COF PyIm , which achieves efficient spatiotemporal coupling between in situ H 2 O 2 generation and enzymatic hydroxylation of the C–H bond. This integrated photobiocatalyst can achieve 90% yield, >99% enantiomeric excess ( ee ), and a turnover number of 41,666 in the asymmetric hydroxylation of ethylbenzene. It also exhibits excellent reusability (retaining 70.4% of its initial activity after six cycles) and broad substrate scope.