Construction and DFT Elucidation of a 2D Europium-Organic Framework with Integrated Porosity and Acid-Base...

Developing structurally defined metal-organic catalysts that integrate CO2 enrichment, substrate activation, and catalytic durability remains essential for sustainable carbon utilization. Herein, a fluorinated two-dimensional europium-organic framework of {[Eu2(HFDPY)2(DMF)4]·2DMF·2H2O}n (NUC-171, H4FDPY = 2,6-bis(2,4-dicarboxyphenyl)-4-(o-fluorophenyl)pyridine) was constructed from the tetracarboxylate ligand H4FDPY through a self-assembly strategy. Upon activation, NUC-171a exhibits an accessible microporous architecture with cavity dimensions of 9.9 × 14.8 × 16.4 Å3, a BET surface area of 575.24 m2 g-1, coordinatively accessible Eu3+ centers, pendant carboxyl functionalities, and pyridyl groups, collectively generating a confined multifunctional catalytic environment for CO2 enrichment and epoxide activation. Benefiting from these integrated structural advantages, NUC-171a enables efficient solvent-free CO2 cycloaddition with a broad range of epoxide substrates, affording a maximum isolated yield of 97.9% for the styrene oxide cycloaddition product under 1.1 MPa CO2 pressure at 85 °C. Combined kinetic analysis, thermodynamic evaluation, and density functional theory calculations reveal that the catalytic transformation proceeds through a cooperative mechanism involving Eu-mediated epoxide coordination, bromide-induced ring opening, CO2 incorporation, and subsequent intramolecular cyclization. Furthermore, NUC-171a preserves its catalytic efficiency and structural integrity during recycling experiments and remains effective under simulated dry and humid flue gas atmospheres. This work highlights ligand-directed dimensional regulation coupled with multifunctional microenvironment construction as an effective strategy for developing durable MOF catalysts toward sustainable CO2 capture and conversion.