Ultrafine Pd Nanoparticles on Triphenylphosphine-Covalent Organic Framework for Dual Photo/Thermal Catalysis of Scalable C-C/C-N Cross-Couplings.

Abstract

The development of highly active and reusable heterogeneous catalysts for scalable organic synthesis remains a critical challenge. Here, a covalent organic framework (TyPPc-COF) with aldehyde residues was synthesized and post-modified with triphenylphosphine ligands to construct TyPPc-P-COF. Subsequently, ultrafine Pd nanoparticles (2.73 nm) were uniformly anchored onto TyPPc-P-COF via phosphine-Pd coordination. The resultant TyPPc-P@Pd NPs exhibit dual-mode catalytic functionality: In C-C cross-coupling reactions involving aryl iodides, this catalyst demonstrates excellent performance under both thermal catalytic conditions (50 mg catalyst, TOF = 1060 h^-1) and photocatalytic conditions (30 mg catalyst, TOF = 1780 h^-1), achieving gram-scale yields (>80%). Notably, under both photocatalytic and thermal catalytic conditions, this catalyst also efficiently catalyzes Suzuki-Miyaura, Heck, and Sonogashira C-C coupling reactions involving aryl bromides and aryl chlorides, which typically exhibit lower activity. Furthermore, it has been demonstrated that light irradiation can effectively extend catalytic functionality to C-N bond formation. Stability tests revealed negligible Pd leaching/aggregation after multiple cycles, confirming structural robustness. This work provides a general strategy for designing COF@MNPs merging high activity, recyclability, and environmental compatibility, advancing sustainable organic synthesis.