Ion Receptors
Ion receptors could be used for the extraction of toxic or radioactive cations and anions from water or the recycling of valuable raw materials, providing means for water purification and decontamination. Supramolecular chemistry has been concerned with cation receptors since the seminal work of Pedersen, Lehn, and Cram on crown ethers, cryptands, and spherands, respectively. Since then, cation receptor chemistry represents an important research field, which has also addressed the challenge of developing systems that can efficiently work in water.