Zirconium-Based Nanoscale Metal–Organic Framework with Metal-Bridged Cationic Linkers for the Selective Removal of Anionic Dyes

A nanoscale metal–organic framework (MOF) based on zirconium, featuring the stacking of a layered structure, has been successfully synthesized. The linear dicarboxylic acid ligand FeTPY2 was built from a unique coordination–dimerization strategy, through the coordination of terpyridyl group with ferrous ions. This approach offers a methodology for extending the length of ligands, which is rarely employed in the MOF design. Subsequently, this ligand was used for making Zr-FeTPY2. The deliberate incorporation of cationic Fe2+ units within Zr-FeTPY2 renders it highly effective in the selective adsorption of anionic dyes, with a loading capacity of 2.84 g/g for Acid Red 94. This result demonstrates the superiority of the developed Zr-FeTPY2 over charge-neutral UiO-68, providing a viable strategy for sustainable water treatment and dye recovery.