Synthesis and Complexing Ability of Azacrownophanes: The Cyclodextrin Catalysis of the Photochemical Cyclization Reaction

Azacrownophanes were efficiently prepared by the irradiation of precursor ammonium chlorides in the presence of -CD (-cyclodextrin) in aqueous solution, by repressing the amino group-quenching effect by inclusion of the styrene moieties in -CD. In liquid–liquid extraction, azacrownophanes (6 and 7) showed affinity toward both Ag⁺ and Pb²⁺ cations in a series of heavy metal nitrates. Both 6 and 7 formed 1:1 complexes with the above two cations, according to ¹³C NMR titration and ESI-MS analysis.