Homochiral Porous Framework as a Platform for Durability Enhancement of Molecular Catalysts

Self-quenching and vulnerability of active sites are major issues posed for practical applications of highly efficient chiral organometallic catalysts. Here, we demonstrate an effective strategy to address these challenges by constructing them into homochiral porous frameworks, which renders them with extraordinary resistance against deactivation yet fully retains the intrinsic catalytic activities and selectivities under heterogeneous systems. Representatively, after partial metalation of the porous chiral phosphoramidite ligand-based frameworks (Phos-HPFs) with Rh species, the afforded catalysts exhibit dramatically enhanced durability while maintaining the activity and selectivity of the homogeneous counterparts in asymmetric hydrogenation of olefins. The rigid framework of Phos-HPFs can isolate the active sites, thus preventing the self-quenching from forming coordinatively saturated complexes, while the active sites surrounded by dense free chiral ligands in Phos-HPFs can inhibit them from decomposing into metallic particles. Our work thereby highlights the advantages of HPFs for the deployment of catalysts, which offers an opportunity for enhancing the utilization efficiency rather than merely having the benefits of easy separation and recycling of the chiral catalysts.