Robust Nitro-Functionalized {Zn<sub>3</sub>}-Organic Framework for Excellent Catalytic Performance on Cycloaddition Reaction of CO<sub>2</sub> with Epoxides and Knoevenagel Condensation
Meiyu Ren, Chong Li, Tuoping Hu, Liming Fan, Xiutang Zhang
Abstract
Adjusting the Lewis acid–base sites in MOF-based catalysts to meet the demand for catalytic CO 2 chemical fixation is a huge challenge. Herein, a highly robust rectilinear {Zn 3 }-based metal–organic framework of {[Zn 3 (TNTNB) 2 (4,4′-bip)(H 2 O) 2 ]·5DMF·9H 2 O} n ( NUC-80 ) was generalized from the solvothermal condition (H 3 TNTNB = 1,3,5-tri(3-nitro-4-carboxyphenyl)-2,4,6-trinitrobenzene, 4,4′-bip = 4,4′-bipyridine). Activated NUC-80a not only owns the large void volume (58%) and two kinds of solvent-accessible channels: rhombic-like ( ca . 14.24 × 14.57 Å) along a axis and rectangular-like ( ca . 11.72 × 14.48 Å) along b axis, but also is functionalized by rich metal sites and plentiful nitro groups on its inner surface. Performed catalytic experiments confirmed that NUC-80a could efficiently catalyze the cycloaddition reaction of CO 2 with epoxides and Knoevenagel condensations of aldehydes and malononitrile under mild conditions with a high turnover frequency (TOF). Hence, this work provides a nitro-functionalized metal cluster-based nanoporous metal–organic framework with a wide range of potential applications such as catalysis, gas adsorption, and separation.