Robust Fluorine-Functionalized {Ln}-Organic Frameworks for Excellent Catalytic Performance on Cycloaddition of CO with Epoxides and Knoevenagel Condensation.

Lanthanide-organic frameworks (LnOFs) are a class of promising catalysts on a large number of organic reactions because of the higher coordination number of Ln ions, inspired by which exploratory preparation of cluster-based LnOFs was carried out by us. Herein, the exquisite combination of spindly [Ln(μ-OH)(CO)(HO)] clusters (abbreviated as {Ln}) and fluorine-functionalized tetratopic ligand of 2',3'-difluoro-[-terphenyl]-3,3″,5,5″-tetracarboxylic acid (F-HPTTA) engendered two highly robust isomorphic nanoporous frameworks of {Ln(FPTTA)(μ-OH)(HO)} (, = and ). compounds are rarely reported {Ln}-based 3D frameworks with nano-caged voids (19 Å × 17 Å), which are shaped by twelve [Ln(μ-OH)(COO)] clusters and eight completely deprotonated F-PTTA ligands. Activated compounds are characterized by plentiful coexisted Lewis acid-base sites of open Ln sites, capped μ-OH, and -F. Judged by the ideal adsorbed solution theory (IAST), activated had a high CO/CH adsorptive selectivity with the value of 12.7 (CO/CH = 50/50) and 9.1 (CO/CH = 5/95) at 298 K, which could lead to high-purity CH (≥99.9996%). Furthermore, catalytic experiments exhibited that , as a representative, could efficiently catalyze the cycloaddition reactions of CO with epoxides as well as the Knoevenagel condensation reactions of aldehydes and malononitrile. This work proves that the {Ln}-based skeletons of with chemical stability, heterogeneity, and recyclability are an excellent acid-base bifunctional catalyst for some organic reactions.