Selective Capture of Small Environmental Pollutants by Cyclohexanohemicucurbit[n]urils ^†

Persistent organic pollutants that occur in different environmental matrices create a need for their sensing, removal and remediation. Cyclohexanochemicucurbit[n]urils (cycHC[n], n = 6 or 8) are chiral macrocyclic cavitands with a well-defined electron-deficient cavity suitable for the accommodation of various electron-rich guests [1,2,3]. The current work describes the application of cycHC[8] as a molecular container for the encapsulation of small neutral organic molecules, including environmental pollutants (mustard gas degradation products, haloalkanes) and biologically active compounds. The formation of inclusion complexes in solid state was confirmed via SC-XRD. Complexation studies in solution through 1H NMR and ITC revealed host–guest interactions between cycHC[8] and hydrophobic S- and O-containing neutral heterocycles, as well as small haloalkanes, in methanol and methanol–water media, resulting in stronger binding upon an increase in solvent polarity. Since the macrocycle is insoluble in water, it was further utilized for the selective capture of the neutral guests from aqueous solutions [3].