Influence of Pd speciation and support interactions for Suzuki reactions

The carbon-carbon bond-formation via the Suzuki reaction is widely used in the pharmaceutical and chemical industries, typically catalyzed by homogeneous palladium (Pd)-ligand complexes. Despite their effectiveness, these catalysts face challenges such as difficult Pd separation and limited reusability. This study targets heterogeneous single atom catalysts (SACs) on varied supports, where Pd-UiO-66-NH₂ metal-organic framework (MOF), synthesized via a ball milling method, was evaluated against Pd/TiO₂ and Pd/C in Suzuki coupling reactions. Characterization data (TEM, XRD, DRIFTS, EDX, chemisorption) revealed that Pd-UiO-66-NH₂ predominantly features isolated Pd atoms, while Pd/TiO₂ contains both single atoms and nanoparticles and Pd/C has predominately nanoparticles. Turnover frequencies for varied substrates trended as Pd-UiO-66-NH₂>Pd/TiO₂>Pd/C, consistent with fitted kinetic parameters. Hot filtration experiments indicated reactivity from each catalyst stemmed from leached Pd. These results highlight the potential of SACs and the importance of support choice for achieving high catalytic efficiency with minimal metal loading, aligning with green chemistry principles and demonstrating the promising role of MOFs as efficient platforms for SACs.