Engineering Fluorinated Nanochannels in a Robust Tb4-Cluster MOF for Synergistic Catalysis of CO2 Fixation and C-C Bond Formation.

The rational design of metal-organic frameworks (MOFs) with well-defined and cooperative catalytic microenvironments is essential for improving their performance in heterogeneous catalysis. In this work, a fluorine-functionalized rare-earth metal-organic framework, NUC-162, has been constructed from tetranuclear {Tb2(μ3-OH)2} clusters and fluorinated organic linkers. Single-crystal structural analysis reveals a robust three-dimensional framework featuring permanent porosity and accessible channels. Upon thermal activation, NUC-162a exposes defect-accessible metal sites and multifunctional acid-base functionalities within the confined pore environment. Owing to the combined effects of Lewis acidic terbium centers, Lewis basic heteroatoms, and Brønsted hydrogen-bond donors, NUC-162a exhibits effective catalytic activity toward CO2-epoxide cycloaddition as well as Knoevenagel condensation under relatively mild conditions. The catalyst demonstrates good substrate tolerance, satisfactory selectivity, and recyclability, indicating its structural stability under catalytic conditions. Control experiments suggest that the regulated pore surface chemistry and cooperative acid-base interactions play an important role in promoting substrate activation and reaction efficiency. This study illustrates that fluorine functionalization represents a viable approach to modulating the catalytic microenvironment of rare-earth MOFs and provides useful insights for the development of porous framework catalysts for CO2-related transformations.