Selective Binding and Precipitation of Cesium Ions from Aqueous Solutions: A Size‐Driven Supramolecular Reaction

The nuclear disasters of Chernobyl and Fukushima presented an urgent need for finding solutions to treatment of radioactive wastes. Among the by‐products of nuclear fission is radioactive 137Cs, which evokes an environmental hazard due to its long half‐life (>30 years) and high solubility in water. In this work, a water‐soluble organic ligand, readily obtained from alloxan and 1,3,5‐benzenetriol, has been found to selectively bind and precipitate Cs+ ions from aqueous solutions. The special rigid structure of the ligand, which consists of a “tripodal” carbonyl base above and below an aromatic plane, contributes to the size‐driven selectivity towards the large Cs+ ions and the formation of a giant, insoluble supramolecular complex. In addition to the low costs of the ligand, high yields and effectiveness in precipitating Cs+ ions, the Cs‐complex revealed a high endurance to continuous doses of γ‐radiation, increasing its potential to act as a precipitating agent for 137Cs.