Highly efficient extraction of sulfate ions with a tripodal hexaurea receptor

Fatal extraction: The Hofmeister bias for sulfate ions in aqueous environments can be overcome by using a tripodal hexaurea receptor (L) that completely encapsulates the sulfate ion in a complementary cavity protected by hydrophobic aromatic rings (see picture; C-gray, N-blue, O-red, S-yellow). Almost quantitative extraction of sulfate ions from an aqueous to an organic phase is achieved when this receptor is used as a liquid-liquid extractant.