Fluorine-Bond Donors Escort Anions Past Membranes

Small, perfluorinated molecules with the ability to form halogen bonds can help transport anions across the lipid bilayer membrane of cells—a complex task that usually requires the concerted actions of large proteins, report Stefan Matile of the University of Geneva and colleagues (Nat. Commun., DOI: 10.1038/ncomms1902). Such effective, small transport systems have numerous potential applications, including drug delivery and sensors. Researchers have previously attempted to use small molecules such as detergents to transport ions, but these efforts have caused membrane destruction and content leakage. Matile’s group found, however, that molecules such as perfluoroiodohexane and tetrafluorodiiodobenzenes surround chloride and hydroxide ions, forming strong, directional halogen bonds. The halogen-bonded complexes then slip across lipid bilayer membranes selectively. Matile and coworkers note that one of these molecules, trifluoroiodomethane, contains only one carbon and therefore represents the smallest possible version of the organic ion transporters.