Viologen-Based Cationic Metal–Organic Framework for Efficient Cr2O72– Adsorption and Dye Separation

作者：Xiaoman Yang, Chaoyue Yan, Zhiyuan Li, Xin Li, Qin Yu, Tingting Sang, Yanli Gai, Qingfu Zhang, Kecai Xiong · 发表于：Inorganic Chemistry · 年份：2021 · DOI：10.1021/acs.inorgchem.1c00404 · 被引用次数：51 · 研究领域：Metal-Organic Frameworks: Synthesis and Applications、Polyoxometalates: Synthesis and Applications、X-ray Diffraction in Crystallography

A novel cationic metal–organic framework composed of {Cu 2 (COO) 4 } paddle-wheel units and a tetracarboxylic viologen derivative, namely, {[Cu 2 (bdcbp)(H 2 O) 2 ]·2NO 3 ·2H 2 O} n ( Cu-CMOF, H 4 bdcbpCl 2 = 1,1′-bis(3,5-dicarboxyphenyl)-4,4′-bipyridinium dichloride), has been successfully synthesized and structurally characterized. In Cu-CMOF, the {Cu 2 (COO) 4 } unit and viologen derivative both act as four-connected nodes forming an ssb-type cationic network with 4 2 .8 4 topology, in which the positive charges are distributed on the organic viologen moieties. Deeper insight of the structure indicates that the 3D architecture of Cu-CMOF can be seen as packing of a 26-faceted polyhedral cage and two cuboid cages. Notably, Cu-CMOF displays a highly efficient anion exchange ability for capture and removal of anionic pollutants. UV–vis absorption spectra and digital images demonstrate that Cu-CMOF is capable of adsorbing the dichromate anion and anionic dyes effectively, such as methyl orange (MO – ), Congo red (CR 2– ), and New Coccine (NC 3– ). Meaningfully, anionic dyes (MO –, CR 2–, and NC 3– ) can be efficiently and selectively removed by Cu-CMOF in the presence of cationic dye methylene blue (MLB + ). Such behaviors of anionic pollutant adsorption and dye separation are mainly caused by an ion-exchange process facilitated by the large cavity and decentralized distribution of positive charge in Cu-CMOF .