We report halogen-bonded complexes between 1-polyfluoroalkyl-3-alkylimidazolium iodides and mono-iodoperfluoroalkanes of different chain lengths or di-iodoperfluorooctane. 19F NMR analyses revealed that the preferred stoichiometry between the donors and acceptors is 1 : 1 in the cases of the mono-iodoperfluoroalkanes, and 2 : 1 with di-iodoperfluorooctane, as a result of the monodentate behavior of the iodide anion (halogen bond acceptor). Single crystal X-ray diffraction analyses showed the presence of a perfluorinated superanion, which interdigitates with the cation fluorinated chains, favoring the formation of lamellar structures. All of the obtained supramolecular complexes exhibit enantiotropic liquid crystalline phases over a broad range of temperatures. Most of the obtained complexes show melting points lower than 100 °C, two of them being liquid at room temperature, thus representing a new family of fluorinated ionic liquid crystals.

Tuning of Ionic Liquid Crystal Properties by Combining Halogen Bonding and Fluorous Effect

Cavallo G.;Rosati M.;Pilati T.;Terraneo G.;Resnati G.;Metrangolo P.
2021

Abstract

We report halogen-bonded complexes between 1-polyfluoroalkyl-3-alkylimidazolium iodides and mono-iodoperfluoroalkanes of different chain lengths or di-iodoperfluorooctane. 19F NMR analyses revealed that the preferred stoichiometry between the donors and acceptors is 1 : 1 in the cases of the mono-iodoperfluoroalkanes, and 2 : 1 with di-iodoperfluorooctane, as a result of the monodentate behavior of the iodide anion (halogen bond acceptor). Single crystal X-ray diffraction analyses showed the presence of a perfluorinated superanion, which interdigitates with the cation fluorinated chains, favoring the formation of lamellar structures. All of the obtained supramolecular complexes exhibit enantiotropic liquid crystalline phases over a broad range of temperatures. Most of the obtained complexes show melting points lower than 100 °C, two of them being liquid at room temperature, thus representing a new family of fluorinated ionic liquid crystals.
fluorous effects
halogen bonding
ionic liquids
liquid crystals
self-assembly
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/1168435
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