A magnetic pore-confined catalyst with ionic liquids supported on MOFs for the synthesis of aryl-oxazolidinones: design, performance, and recyclability

Various methods have been explored for preparing heterogeneous catalysts using metal-organic framework (MOF) supported ionic liquids (ILs); however, it is challenging to develop such a synergistic catalyst that combines high efficiency, stability, the capability of maintaining immobilized ILs and active components, and high recovery efficiency. In this study, we successfully developed a magnetic MOF sub-nanostructured carrier by integrating organic UiO-66 with magnetic nanoparticles (MNPs). The resulting magnetic pore-confined catalyst, named MAG-UiO-66-IL(OAc), was prepared by in-situ self-assembly of pore-confining [C4mim] [OAc] within the nano-cavities of the magnetic MOF carrier. The morphology, structure, and thermal properties of the magnetic pore-confined catalyst were comprehensively characterized using various techniques. The novel catalyst MAG-UiO-66-IL(OAc) demonstrated remarkable catalytic efficiency in transforming cyclic carbonates and aryl amines to aryl-oxazolidinones, achieving yields up to 95% under mild solvent-free conditions. Furthermore, the catalyst showed exceptional recyclability, retaining its catalytic activity after ten successive reuses. Notably, the catalyst displayed excellent performance for reactions involving large-size reactants, expanding the range of substrate usability beyond previously reported solid-loading catalysts. Theoretical calculations were also conducted to complement the experimental results, providing valuable insights into the structure–activity relationship between the magnetic MOF carrier and the ionic liquid. These findings emphasize the significance of molecular-scale confinement on reactant diffusion and the overall reaction process, offering valuable guidance for the design of catalyst microstructures and the modulation of reaction performance.