Viologen-Based Cationic Metal–Organic Framework for Antibiotics Detection and MnO₄^– Removal in Water

A novel Eu(III)-based cationic metal–organic framework (Eu-CMOF), formulated as [Eu(bcbp)(tdc)(H2O)3]·Cl·5H2O (H2bcbpCl2 = 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) dichloride, H2tdc = 2,5-thiophenedicarboxylic acid), has been solvothermally synthesized. Eu-CMOF displays a four-fold interpenetrating three-dimensional cationic diamondoid network, in which the positive charges of the framework are derived from the bipyridinium moiety of the bcbp ligand. Notably, Eu-CMOF exhibits a good sensing ability to nitrofurantoin and nitrofurazone in aqueous solution with high selectivity and a low limit of detection. And the quenching coefficient and mechanism have also been further investigated. Meanwhile, Eu-CMOF also possesses high uptake kinetics and adsorption capacity for MnO4–, which is mainly attributed to the cationic framework, as well as the decentralized distribution of the positive charge.