An Imide-Decorated Indium-Organic Framework for Efficient and Selective Capture of Carcinogenic Dyes with Diverse Adsorption Interactions

A functional indium-organic framework with an anionic skeleton, [(CH3)2NH2][In(BDCPPI)]·0.5DMF·H2O (compound 1, H4BDCPPI = N,N′-bis(3,5-dicarboxyphenyl)pyromellitic diimide, DMF = N,N-dimethylformamide), has been solvothermally synthesized. Compound 1 with a (4, 4)-connected pts network is constructed by negative [In(OOC)4]− secondary building units (SBUs) and expanded tetracarboxylate ligands with functional imide groups. Meanwhile, the overall framework possesses large open channels of 17.3 × 5.5 Å with a high solvent-accessible volume that occupied about 69.2% of the total cell volume. Due to its anionic skeleton and imide-functional channels, compound 1 can efficiently adsorb large-sized carcinogenic Basic Red 9 (BR9) and Basic Violet 14 (BV14) under the synergetic promotion of Coulombic interaction, hydrogen bonding, and ion exchange and can display a repelling effect to anionic dyes. In addition, the maximum adsorption capacities for BR9 and BV14 are as high as 245 and 227 mg g–1, respectively. With regard to series of mixtures with oppositely charged dyes, compound 1 can selectively trap carcinogenic dyes. Therefore, compound 1 should be a promising metal–organic framework (MOF)-based material for the efficient and selective adsorption of carcinogenic dyes.