Defect engineering is a pivotal strategy for tailoring the electronic structure and physicochemical properties of catalysts, yet the straightforward manipulation of defect density in porous materials presents a current challenge. In this work, we achieved precise control over the coordination unsaturated site (CUS) content and pore architecture of Ce-MOF-808 by employing 2-fluorobenzoic acid (2-FBA) as a modifier. Leveraging the pKa disparities among three ligands (1,3,5-tricarboxylic benzoic acid, formic acid, and 2-FBA), we preserved the spn topology of Ce-MOF within an aqueous system, while realizing partial substitution of the auxiliary ligands and saturation of the CUS. The amount of 2-FBA was negatively correlated with the number of ligand defects, and the consequent decrease in Ce3+ content and the increase in the number of ligand linkages also induced crystal structure transformation. The modulation of the defect structure was correlated with the catalytic performance of dicyclopentadiene (DCPD) hydrogenation reaction, in which Ce-MMF0.15, constructed by the modulation of 0.15 mol amount of 2-fluorobenzoic acid, exhibited an optimal ligand defect density and micro-mesoporous structure, enabling almost complete conversion of DCPD at 100 °C and 2 MPa. This article also elucidates the correlation between the regulation of defect density and the accessibility of frustrated Lewis pair (FLP) active sites, guiding the application of novel porous intrinsic FLP materials in hydrogenation catalysis.
