Construction of imide-functionalized aromatic conjugation tetracarboxylate frameworks and adsorption behavior for iodine and selective cationic dyes

Metal-organic frameworks (MOFs) show great potential in environmental contaminants removal owing to their outstanding pore properties and tunable chemical performance. Two new imide-functionalized aromatic conjugation tetracarboxylate frameworks: [Cd4(BDCPPI)2(DMF)2(H2O)3]·2DMF·8H2O (1) and [Zn4(BDCPPI)2(DMF)6]·3DMF·4H2O (2) were designed and synthesized under solvothermal conditions. Due to the micropore size and aromatic conjugation properties with the 3D network structures, complexes 1 and 2 have abundant active sites, resulting in strong iodine capture and dye adsorption capacity. The excellent iodine capture ability on complexes 1 and 2 might due to the interaction of iodine with the carbonyl oxygen atom (I⋯O) and the benzene ring (I···π). The materials were charge and size selective for the adsorption of dyes, and the presence of abundant imide-functionalized groups in the channels can form hydrogen-bonding interactions with dye molecules to promote their adsorption properties. In addition, the high I2 adsorption and release capacity of complexes 1 and 2 indicate their wide application prospects in nuclear waste management. Therefore, the as-synthesized MOFs can be used as potential multifunctional adsorbents for further removal of organic dyes and iodine from wastewater.