From molecules to materials: Engineering new ionic liquid crystals through halogen bonding

Gabriella Cavallo*, Duncan W. Bruce, Giancarlo Terraneo, Giuseppe Resnati, Pierangelo Metrangolo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid crystals (ILCs). Taking advantages of the high specificity of XB for haloperfluorocarbons and the ability of anions to act as XB-acceptors, we obtained supramolecular complexes based on 1-alkyl-3-methylimidazolium iodides and iodoperfluorocarbons, overcoming the well-known immiscibility between hydrocarbons (HCs) and perfluorocarbons (PFCs). The high directionality of the XB combined with the fluorophobic effect, allowed us to obtain enantiotropic liquid crystals where a rigid, non-aromatic, XB supramolecular anion acts as mesogenic core. X-ray structure analysis of the complex between 1-ethyl-3-methylimidazolium iodide and iodoperfluorooctane showed the presence of a layered structure, which is a manifestation of the well-known tendency to segregation of perfluoroalkyl chains. This is consistent with the observation of smectic mesophases. Moreover, all the reported complexes melt below 100 °C, and most are mesomorphic even at room temperature, despite that the starting materials were non-mesomorphic in nature. The supramolecular strategy reported here provides new design principles for mesogen design allowing a totally new class of functional materials.

Original languageEnglish
Article numbere55636
Number of pages11
JournalJournal of Visualized Experiments
Volume2018
Issue number133
DOIs
Publication statusPublished - 24 Mar 2018

Bibliographical note

© The Authors 2018.

Keywords

  • Fluorophobic effect
  • Halogen bonding
  • Haloperfluorocarbons
  • Imidazolium salts
  • Ionic liquids
  • Liquid crystals
  • Self-assembly
  • Supramolecular chemistry

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