A Bifunctional Anionic Metal–Organic Framework: Reversible Photochromism and Selective Adsorption of Methylene Blue

A novel anionic Cd(II)-organic framework, {[(CH3)2NH2]2[Cd(H2BIPA-TC)2]·5(DMF)}n, has been solvothermally synthesized from a naphthalenediimide-based ligand 5,5′-(1,3,6,8-tetraoxobenzo[Imn][3,8]phenanthroline-2-7-diyl)bis-1,3-benzenedicarboxylic acid (H4BIPA-TC). In the crystal structure, Cd (II) cations link H2BIPA-TC2– ligands into a 3-fold interpenetrated 3D network with dia topology. Interestingly, the title compound exhibits a reversible photochromic property and excellent adsorption capacity of Methylene Blue (MB) (149 mg/g) as compared with Rhodamine (RhB), Methyl Orange (MO), and Solvent Yellow 2 (SY2) due to electrostatic interaction in aqueous solution.