An Exceptionally Water Stable Metal-Organic Framework with Amide-Functionalized Cages: Selective CO2/CH4 Uptake and Removal of Antibiotics and Dyes from Water

As the main organic pollutants in wastewater, antibiotics and organic dyes are harmful to the environment and public health, and their removal is important but challenging. In this work, highly porous 3D metal-organic frameworks (MOFs) [M-2(PDAD)(H2O)](n) (PCN-124-stu; M = Cu, Zn; H(4)PDAD = 5,5'-(pyridine-3,5-dicarbonyl)bis(azanediyl)diisophthalic acid) were synthesized, and PCN-124-stu(Cu) shows excellent chemical and thermal stability. PCN-124-stu(Cu) was used as a host for efficient extraction of various organic dyes, especially the large-molecule dye Coomassie brilliant blue, and fluoroquinolones from water, in comparison with five common MOFs, zeolite 13X, and activated carbon. PCN-124-stu(Cu) exhibits absolute predominance for fluoroquinolone adsorption among these microporous materials because of the H-bonds between fluoroquinolone molecules and the amide groups in the frameworks, except for MIL-100(Cr), which is a mesoporous MOF. Moreover, PCN-124-stu(Cu) could release fluoroquinolones slowly in physiological saline and retained its framework structure after four adsorption/desorption cycles. In addition, PCN-124-stu(Cu) can be used as a platform for selective adsorption of CO2/CH4.