title: Self-assembly of a double-helical complex of sodium.
abstract: Spontaneous self-organization of helical and multiple-helical molecular structures occurs on several levels in living organisms. Key examples are alpha-helical polypeptides, double-helical nucleic acids and helical protein structures, including F-actin, microtubules and the protein sheath of the tobacco mosaic virus. Although the self-assembly of double-helical transition-metal complexes bears some resemblance to the molecular organization of double-stranded DNA, selection between monohelical, double-helical and triple-helical structures is determined largely by the size and geometrical preference of the tightly bound metal. Here we present an example of double-helical assembly induced by the weaker and non-directional interactions of an alkali-metal ion with an organic ligand that is pre-organized into a coil. We have characterized the resulting complex by two-dimensional NMR and fast-atom-bombardment mass spectrometry. These results provide a step toward the creation of molecular tubes or ion channels consisting of intertwined coils.
authors.affiliation: Department of Chemistry, State University of New York, Stony Brook 11794-3400.
authors.forename: T W
authors.initials: TW
authors.lastname: Bell
authors.forename: H
authors.initials: H
authors.lastname: Jousselin
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010618:Phenanthrolines / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D012964:Sodium / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D010618:Phenanthrolines; D011725:Pyridines; D012964:Sodium