99Tco4−: Selective recognition and trapping in aqueous solution

Abstract

Too hot to handle: Unprecedented affinity and specificity for 99TcO4− in aqueous solution was shown with the p-xylyl azacryptand in the hexaprotonated form (see scheme). A crystal structure of the complex reveals how the anion fits within the cavity of the cage, and the formation of multiple H-bond interactions with protonated amino groups stabilize the adduct.