Truncated monomer‐mediated defect engineering in robust metal‐covalent organic frameworks for atmospheric CO 2 conversion

Abstract Heterogeneous catalytic conversion of CO 2 into high‐value 2‐oxazolidinones remains challenging due to intrinsically low activity, often necessitating corrosive superbases as co‐catalysts that compromise sustainability. Herein, we present a rational defect‐engineering strategy for constructing cyclic trinuclear Cu(I)‐based covalent organic frameworks (dCOF‐Cu 3 TG‐ x %Im), which feature integrated triple active sites and optimized mass transfer channels. By strategically introducing imidazole‐2‐carboxaldehyde as a truncated monomer during synthesis, missing‐linker defects are created to concurrently accommodate Lewis acidic Cu(I) centers and Lewis basic moieties (imidazole and –NH 2 groups), thereby eliminating the requirement for external superbases. The optimized dCOF‐Cu 3 TG‐10%Im catalyst exhibits exceptional activity, achieving 2‐oxazolidinone yields up to 92% for a wide range of propargylamine substrates under mild (80°C, 0.1 MPa CO 2 ) and superbase‐free conditions. The catalyst also demonstrates robust recyclability and prolonged stability. Insights into the synergistic catalytic mechanism are elucidated through combined theoretical calculations and molecular dynamics simulations, providing an important theoretical foundation for efficient CO 2 valorization.