Precise Construction of Heterobimetallic Covalent Organic Frameworks for Cooperative Photocatalysis of Defluorination

Abstract

Precisely positioning two distinct metal centers within covalent organic frameworks (COFs) is inherently difficult because competitive coordination and uncontrolled metal distribution often compromise structural integrity. Herein, we report a rational strategy that overcomes this challenge, enabling the atomically precise construction of a heterobimetallic COF incorporating nickel porphyrin and iron quinoline units. This synthesis leverages fundamental differences in the thermodynamic and kinetic behaviors of metal ions and organic building blocks and achieves near-quantitative metal occupancy at predetermined coordination sites while preserving framework crystallinity. Despite coordinating independently, the two metal centers engage in strong electronic coupling through local orbital hybridization, establishing an efficient charge-transfer pathway that promotes directional electron migration and suppresses recombination. This bimetallic architecture drives efficient defluorination photocatalysis with broad substrate tolerance and robust recyclability, achieving performance inaccessible to any photocatalysts reported to date. Our work provides a generalizable platform for designing heterobimetallic COFs with tailored charge-transfer kinetics for complex organic transformations.