Stabilizing Pd Nanoparticles via N,O-Chelation in a MOF for General Reductive Amination

Herein, we developed a Pd/UiO-66-NO catalyst for the reductive amination of benzaldehyde with aniline to synthesize N -benzylaniline. Through post-synthetic modification, salicylaldehyde was incorporated into the UiO-66-NH ₂ framework to construct a support (UiO-66-NO) featuring N,O-bidentate chelating sites, which enabled the stabilization of highly dispersed Pd nanoparticles. Characterization results confirmed the preserved framework integrity and demonstrated efficient secondary amine synthesis under mild conditions (60 °C, 3 h). The catalyst exhibited broad substrate scope with excellent functional group compatibility. Mechanistic studies revealed a two-step pathway involving amine-aldehyde condensation followed by hydrogenation of the imine intermediate. ¹ H NMR and GC kinetic analyses evidenced rapid imine formation and subsequent efficient reduction to the secondary amine. This work offers a new strategy for designing high-performance heterogeneous catalysts and paves a promising avenue for sustainable synthesis of secondary amines.