title: Ion Aggregation and R3N+-C(R)-H···NR3Hydrogen Bonding in a Fluorous Phase.
abstract: Potentiometric selectivities show that in fluorous ion-selective electrode membranes the tetrabutylammonium ion binds to fluorophilic proton ionophores. For the ionophore bis[3-(perfluorooctyl)propyl](2,2,2-trifluoroethyl)amine, this type of interaction is confirmed by the effect of the ionophore on the ionic conductivity of perfluoro(perhydrophenanthrene) solutions of a fluorophilic NBu4+salt. In this system, ion pairs, triple ions, and higher ionic aggregates dominate over single ions, and the ionophore increases the conductivity by favoring the formation of ion aggregates with a net charge. These observations are consistent with the formation of R3N+-C(R)-H···NR3type hydrogen bonds between the nitrogen atom of the ionophore and the hydrogen atoms in the α position to the positively charged quaternary ammonium center of NBu4+. Similar interactions were observed in a number of crystalline phases. To date, observations of C-H···N type hydrogen bonds in liquid phases have been very few, and solution-phase N+-C-H···N type hydrogen bonds have not been reported previously. Interestingly, no interactions between NBu4+and the more basic ionophore tridodecylamine were observed in conventional plasticized poly(vinyl chloride) membranes doped with the ionophore tridodecylamine, emphasizing the uniquely low polarity of fluorous phases.
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Evan L
authors.initials: EL
authors.lastname: Anderson
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gingery
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Boswell
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Xin V
authors.initials: XV
authors.lastname: Chen
authors.affiliation: Institute of Chemistry, Eötvös Loránd University , P.O. Box 32, H-1518 Budapest 112, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Rábai
authors.affiliation: Department of Chemistry, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States.
authors.forename: Philippe
authors.initials: P
authors.lastname: Bühlmann
mesh_terms: D005461:Fluorine / Q000737:chemistry*; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D011199:Potentiometry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D007477:Ions; D000644:Quaternary Ammonium Compounds; D005461:Fluorine; C009405:tetrabutylammonium