Nanoporous {Y 2 }-Organic Frameworks for Excellent Catalytic Performance on the Cycloaddition Reaction of Epoxides with CO 2 and Deacetalization-Knoevenagel Condensation.

Stable metal-organic frameworks containing periodically arranged nanosized pores and active Lewis acid-base active sites are considered as ideal candidates for efficient heterogeneous catalysis. Herein, the exquisite combination of [Y 2 (CO 2 ) 7 (H 2 O) 2 ] cluster (abbreviated as {Y 2 }) and multifunctional linker of 2,4,6-tri(2,4-dicarboxyphenyl)pyridine (H 6 TDP) led to a nanoporous framework of {[Y 2 (TDP)(H 2 O) 2 ]·5H 2 O·4DMF} n ( NUC-53 , NUC = North University of China), which is a rarely reported binuclear three-dimensional (3D) framework with hierarchical tetragonal-microporous (0.78 nm) and octagonal-nanoporous (1.75 nm) channels. The inner walls of these channels are aligned by {Y 2 } clusters and plentifully coexisted Lewis acid-base sites of Y III ions and N pyridine atoms. Furthermore, NUC-53 has a quite large void volume of ∼65.2%, which is significantly higher than most documented 3D rare-earth-based MOFs. The performed catalytic experiments exhibited that activated NUC-53 showed a high catalytic activity on the cycloaddition reactions of CO 2 with styrene oxide under mild conditions with excellent turnover number (TON: 1980) and turnover frequency (TOF: 495 h -1 ). Moreover, the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile could be efficiently prompted by the heterogeneous catalyst of NUC-53 . These findings not only pave the way for the construction of nanoporous MOF based on rare-earth clusters with a variety of catalytic activities but also provide some new insights into the catalytic mechanism.