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 MAGUiO-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.