A Zwitterionic Ligand‐Based Cationic Metal‐Organic Framework for Rapidly Selective Dye Capture and Highly Efficient Cr₂O₇²⁻ Removal

Abstract

A cationic metal-organic framework (MOF), [Cu L(H O) ]⋅(NO ) ⋅5.5 H O (1) has been successfully synthesized from a zwitterionic ligand 1,1'-bis(3,5-dicarboxyphenyl)-4,4'-bipyridinium chlorine ([H L]Cl ). The framework of compound 1 contains classical {Cu (O C) } paddlewheels, and possesses typical nbo-type topology and two types of channels with sizes of 5.0 and 15.54 Å. Benefitting from the 3D cationic framework and high pore volume, compound 1 shows interesting selective adsorption ability for anionic dyes. Such material can be successfully employed in a chromatographic column to efficiently separate mixed dyes of Fluorescein Sodium and Methylene Blue. In addition, compound 1 exhibits excellent Cr O removal capacity with maximum adsorption amount of 222.5 mg g , which ranks among the higher Cr O adsorption amounts of MOF materials ever reported, based on ion-exchange. The strategy to construct cationic MOFs based on zwitterionic ligands will promote the development of functional porous materials for the capture and removal of anionic pollutant species from contaminated liquid.

Optimizing Fe‐Based Metal‐Organic Frameworks through Ligand Conformation Regulation for Efficient Dye Adsorption and C2H2/CO2 Separation

“…The modification of clusters or ligands has great potential in removing pollutants such as dyes in wastewater. The amount of textile dyes discharged globally each year far exceeds the natural purification capacity, so there is an urgent to develop effective organic dye adsorbents [26–28] . In addition to the higher specific surface area and porosity, the active sites such as −NH 2 and −SH in the channel of MOFs also increase the interaction (such as hydrogen bonding interaction, π‐π interaction, etc.)…”

Anion-Dependent Catalytic C–C Bond Cleavage of a Lignin Model within a Cationic Metal–Organic Framework

“…68% void space). This MOF, [Cu 2 (L)­(H 2 O) 2 ]­(NO 3 ) 2 ·5.5H 2 O ( 1 ), where L = 1,1′-bis­(3,5-dicarboxylatophenyl)-4,4′-bipyridinium (Figure A), is an isoreticular analogue of neutral NOTT-102 , (Figure B) . In addition to being cost-effective and environmentally friendly, copper­(II)-based materials have previously been investigated for their catalytic activity toward C–C bond cleavage of lignin models. , In both NOTT-102 and its charged congener 1 , owing to the paddlewheel nodes of the MOFs, the copper­(II) ions adopt a slightly distorted five-coordinate square pyramidal geometry, with the apical position being occupied by a water molecule.…”

“…, where L = 1,1′-bis(3,5dicarboxylatophenyl)-4,4′-bipyridinium (Figure 1A), 23 isoreticular analogue of neutral NOTT-102, (Figure 1B). 24 In addition to being cost-effective and environmentally friendly, copper(II)-based materials have previously been investigated for their catalytic activity toward C−C bond cleavage of lignin models.…”

“…We also characterized SCN − @1 and Cr 2 O 7 2− @1 by nitrogen adsorption−desorption and observed the same collapse reported for as-synthesized 1 (Figure S12). 23 Nevertheless, the highly porous nature of these materials and the presence of accessible copper(II) sites encouraged us to explore their potential as heterogeneous catalysts in dry organic solvents.…”

Mixed Short and Long Ligands toward the Construction of Metal–Organic Frameworks with Large Pore Openings

“…Also, a blue shift of the maximum absorption peak was observed along with the absorption process, like other reports. 29,30 In the first 10 min, 30% of Cr 2 O 7 2− was removed from water. And 80 min later, the ion-exchange reached its equilibrium point.…”