A Water-Stable Cationic Metal-Organic Framework as a Dual Adsorbent of Oxoanion Pollutants

A three‐dimensional water‐stable cationic metal–organic framework (MOF) pillared by a neutral ligand and with NiII metal nodes has been synthesized employing a rational design approach. Owing to the ordered arrangement of the uncoordinated tetrahedral sulfate (SO42−) ions in the channels, the compound has been employed for aqueous‐phase ion‐exchange applications. The compound exhibits rapid and colorimetric aqueous‐phase capture of environmentally toxic oxoanions (with similar geometries) in a selective manner. This system is the first example of a MOF‐based system which absorbs both dichromate (Cr2O72−) and permanganate (MnO4−) ions, with the latter acting as a model for the radioactive contaminant pertechnetate (TcO4−). Selective uptake: A 3D water‐stable cationic metal–organic framework (MOF) containing free SO42− ions has been synthesized. The compound exhibits rapid, selective, and colorimetric aqueous‐phase capture of environmentally toxic oxoanions. This system is the first example of a MOF‐based adsorbent of both Cr2O72− and MnO4− ions, with the latter acting as a model for the radioactive contaminant TcO4−.