Insoluble Acyclic Cucurbit[n]uril-Type Receptors Capture Iodine from the Vapor Phase

Nuclear energy makes large contributions toward meeting global energy needs, but societal concerns remain high given the impacts of the intended release of radioactive materials including ¹²⁹I and ¹³¹I. In this paper we explore the use of a homologous series of acyclic CB[n] type hosts (H1-H4) as adsorbents of iodine from the vapor phase. We find that H2-H4, but not H1 - perform well in this application with uptake capacities of 2.2 g g^-1, 1.5 g g^-1, and 1.9 g g^-1, respectively. The chemisorptive uptake process involves partial oxidation of catechol walled H2 to quinone walled host and capture of I₃ ^- and I₅ ^-. Solid H2 can be regenerated by treatment with Na₂S₂O₄ and reused at least five times. The x-ray crystal structure of H2 is also reported.