Adenine-based urea receptors in fluorescent recognition of iodide

Adenine-based receptors 1 and 2 are designed and synthesized for selective sensing of iodide over the other halides and carboxylate anions. Both the receptors 1 and 2 use the urea motif for binding carboxylates and halides. Emissions of the naphthalene and the anthracene in 1 and 2, respectively, are monitored in CHCl₃ in detecting the anions. While carboxylates, fluoride, chloride, and bromide increase the emissions of naphthalene and anthracene in both the receptors 1 and 2 during complexation, iodide quenches the emission. Such selective quenching allows iodide to be discriminated from other halides and carboxylate anions.