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

Abstract

We report halogen-bonded complexes between 1-polyfluoroalkyl-3-alkylimidazolium iodides and mono-iodoperfluoroalkanes of different chain lengths or di-iodoperfluorooctane. 19 F 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.

Halogen bonding regulated functional nanomaterials

“…Cavallo and colleagues reported a new family of fluorinated ionic liquid crystals, which was synthesized between 1-polyfluoroalkyl-3-alkylimidazolium iodides and mono-iodoperfluoroalkanes of different chain lengths or di-iodoperfluorooctane. 73 Over a wide range of temperatures, these resulting halogen bonded ionic LCs showed enantiotropic liquid crystalline phases.…”

Copper(II)-Mediated Iodination of 1-Nitroso-2-naphthol

“…We applied this reaction as a starting point to develop a synthetic route to I-NON (Scheme 1). On the one hand, I-NON, as a representative of the group of nitrosonaphthols, can be useful as a chelator for transition metal complexes and this sequestering can be applied for analytic or extraction purposes [19,20]; on the other hand, the iodine functionality in I-NON, acting as a halogen bond (HaB) donor, might be useful for HaB-based crystal engineering [21][22][23][24][25]. Scheme 1.…”

Shaping 1,2,4-Triazolium Fluorinated Ionic Liquid Crystals

“…Aside from the widely explored cationic cores such as imidazolium and pyridinium, [8][9][10] other heterocyclic core ionic structures, such as oxadiazoles and triazoles, which have been mainly investigated for their biological activity, [11][12][13][14] are interesting for their predictable tuning of mesophase behavior [1,15] when segregations between polar charged regions and non-polar aliphatic chains are expected to drive self-assembly. Moreover, the presence of fluorocarbon chains would additionally stress self-organisation [9,16,17] and allow for the formation of ordered, smectic lamellar phases [18][19][20][21] with the appealing property of gas sorption [22].…”