Design of Highly Porous Single-Site Catalysts through Two-Step Postsynthetic Modification of Mixed-Linker MIL-53(Al)

Defined mixed-linker metal-organic frameworks based on MIL-53-NH2(Al) were successfully synthesized under ambient pressure, thus, enabling easy scaling up of the synthesis. The two-step postsynthetic modification reaction of these materials with, first, maleic anhydride and, second, palladium(II) acetate resulted in immobilized palladium(II) complexes at the side chain of the linker molecules. The high porosity of the mixed-linker materials was retained throughout the modification process, which was in contrast to a previous study with pure MIL-53-NH2(Al). The novel palladium-containing materials were applied in Heck-type C-C coupling reactions of bromo-or chlorobenzene with styrene, in which they exhibited high catalytic activity and selectivity.