A Water-Stable Cationic Metal–Organic Framework with Hydrophobic Pore Surfaces as an Efficient Scavenger of Oxo-Anion Pollutants from Water

Water contamination due to heavy metal-based toxic oxo-anions (such as CrO₄²⁻ and TcO₄⁻) is a critical environmental concern that demands immediate mitigation. Herein, we present an effort to counter this issue by a novel chemically stable cationic metal-organic framework (iMOF-2C) with strategic utilization of a ligand with hydrophobic core, known to facilitate such oxo-anion capture process. Moreover, the compound exhibited very fast sieving kinetics for such oxo-anions and a very high uptake capacity for CrO₄²⁻ (476.3 mg g⁻¹) and ReO₄⁻ (691 mg g⁻¹), while the latter being employed as a surrogate analogue for radioactive TcO₄⁻ anions. Notably, the compound showed excellent selectivity even in the presence of other competing anions such as NO₃⁻, Cl⁻, SO₄²⁻, ClO₄⁻. etc.. Furthermore, the compound possesses excellent reusability (up to 10 cycles) and is also employed to a stationary phase ion column to decontaminate the aforementioned oxo-anions from water.