Highly Efficient Extraction of Sulfate Ions with a Tripodal Hexaurea Receptor

Abstract

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.