A nanocaged cadmium-organic framework with high catalytic activity on the chemical fixation of CO2 and deacetalization-knoevenagel condensation

Abstract

Heterogeneous MOFs catalysts have attracted great attention due to the efficient combination of heterogeneity (easy post-reaction separation and recyclability) and homogeneity (active sites and porosity), which inspire us to explore functional MOFs materials with higher catalytic activity on the chemical fixation of CO2 and deacetalization-Knoevenagel condensation. Herein, the self-assembly of Cd2+ and H6TDP under acidic solvothermal condition generated one cadmium-organic framework of {[(CH3)2NH2]2 [Cd2 (TDP) (H2O)2]⋅3DMF⋅2H2O}n (NUC-29, H6TDP = 2,4,6-tris(2,4-dicarboxyphenyl)pyridine) with nano-caged voids and hierarchical microporous channels, which were built on the combination of two kinds of mononuclear units of [Cd (1) (COO)3(H2O)] and [Cd (2) (COO)3(H2O)]. After the removal of solvent molecules by activation, NUC-29 possesses the coexistence of Lewis acid-base sites on the inner surface of channels including all exposed Cd2+ sites and Npyridine sites, which render it an excellent recyclable heterogeneous catalyst to facilitate the cycloaddition reaction of epoxides with CO2 and deacetalization-Knoevenagel condensation under mild conditions.