Nanoporous {Co3}-Organic framework for efficiently seperating gases and catalyzing cycloaddition of epoxides with CO2 and Knoevenagel condensation

Xiutang Zhang; Xiaotong Wang; Chong Li; Tuoping Hu; Liming Fan

doi:10.1016/j.jcis.2023.11.064

Nanoporous {Co₃}-Organic framework for efficiently seperating gases and catalyzing cycloaddition of epoxides with CO₂ and Knoevenagel condensation

J Colloid Interface Sci. 2024 Feb 15:656:127-136. doi: 10.1016/j.jcis.2023.11.064. Epub 2023 Nov 17.

Authors

Xiutang Zhang¹, Xiaotong Wang², Chong Li², Tuoping Hu², Liming Fan³

Affiliations

¹ Shanxi Key Laboratory of Advanced Carbon Based Electrode Materials, School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, PR China. Electronic address: xiutangzhang@163.com.
² Shanxi Key Laboratory of Advanced Carbon Based Electrode Materials, School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, PR China.
³ Shanxi Key Laboratory of Advanced Carbon Based Electrode Materials, School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, PR China. Electronic address: limingfan@nuc.edu.cn.

PMID: 37988780
DOI: 10.1016/j.jcis.2023.11.064

Abstract

Enhancing the catalysis of metal-organic frameworks (MOFs) by regulating inherent Lewis acid-base sites to realize the efficient seperation and chemical fixation of inert carbon dioxide (CO₂) is crucial but challenging. Herein, the solvothermal self-assembly of Co²⁺, 5'-(4-carboxy-2-nitrophenyl)-2,2',2'',4',6'-pentanitro-[1,1':3',1''-terphenyl]-4,4''-dicarboxylic acid (H₃TNBTB) and 4'-phenyl-4,2':6',4''-terpyridine (PTP) generated a highly robust cobalt-organic framework of {[Co₃(TNBTB)₂(PTP)]·7DMF·6H₂O}_n (NUC-82). In NUC-82, the tri-core clusters of {Co₃} with linear shape are bridged by TNBTB^3- to form two-dimensional structure in ac plane, which is further linked by PTP to generate a three-dimensional framework with two kinds of solvent-accessible channels: rhombic-like (ca. 11.57 × 10.76 Å) along a axis and rectangular-like (ca. 7.32 × 11.56 Å) along b axis. Furthermore, it is worth emphasizing that the confined pore environments are characterized by plentiful Lewis acid-base sites of tricobalt clusters, grafted nitro groups and free pyridinyl, high specific surface area and solvent-free nano-caged windows. Activated NUC-82a owns the ultra-high ethylene (C₂H₂) separation performance over the mixture of C₂H₂/CH₄ and CO₂/CH₄ with the selectivity of 223.1 and 44.7. Thanks to the great Lewis-acid sites as well as the large pore volume, activated NUC-82a displays the high catalytic performace on the cycloaddition of CO₂ with epoxides under wield condtions such as amibient pressure. Furthermore, because of the rich Lewis base sites, NUC-82a can efficiently catalyze Knoevenagel condensation of aldehydes and malononitrile. In the above organic reactions, NUC-82a not only shows the high catalytic activity, but also exhibits the high selectivity, satifactory recyclability and easy-to-separate heterogeneity, confirming that NUC-82a is a promising catalyst. Hence, this work provides in-depth insight into the construction of multifunctional MOFs by modifying the traditional ligands with as many Lewis acid-base active sites as possible.

Keywords: Cobalt cluster; Cycloaddition reaction; Heterogeneous catalysis; Knoevenagel condensation; Nitro group.