Nanochannel-based {BaZn}-organic framework for catalytic activity on the cycloaddition reaction of epoxides with CO 2 and deacetalization-Knoevenagel condensation.

Herein, the rare combination of Ba II (5s) and Zn II (3d) in the presence of the structure-oriented TDP 6- ligand generated the nanochannel-based hybrid material {[(CH 3 ) 2 NH 2 ] 2 [BaZn(TDP)(H 2 O)]·DMF·5H 2 O} n (NUC-51, H 6 TDP = 2,4,6-tri(2,4-dicarboxyphenyl)pyridine), which possesses excellent physicochemical characteristics such as nanoscopic channels, high porosity, large specific surface area, and high heat/water-resistance. To the best of our knowledge, this is the first 3D [Ba II Zn II (CO 2 ) 6 (H 2 O)]-based nano-porous host framework, whose activated state possesses the coexistence of Lewis acid-base sites including 4-coordinated Zn 2+ ions, 7-coordinated Ba 2+ ions, uncoordinated carboxyl oxygen atoms, and N pyridine atoms. Catalytic experiments exhibited that activated NUC-51a possesses a high catalytic activity on the cycloaddition reactions of epoxides with CO 2 at 55 °C, which can be ascribed to its structural advantages of nanoscale channels and rich bifunctional active sites. Moreover, NUC-51a could significantly accelerate the deacetalization-Knoevenagel condensation reaction in DMSO solvent at 70 °C.