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

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Halogen bonding is a key non-covalent interaction driving self-assembly.
• Fluorinated compounds offer unique properties for materials applications.
• Ionic liquids are versatile solvents and functional materials.

Purpose of the Study:

• To synthesize and characterize novel halogen-bonded supramolecular complexes.
• To investigate the structural and self-assembly behavior of these complexes.
• To explore the liquid crystalline properties of the resulting materials.

Main Methods:

• Synthesis of 1-polyfluoroalkyl-3-alkylimidazolium iodides.
• Complexation with mono-iodoperfluoroalkanes and di-iodoperfluorooctane.
• Characterization using 19F NMR spectroscopy and single crystal X-ray diffraction.

Main Results:

• Formation of 1:1 and 2:1 complexes depending on the iodoperfluoroalkane.
• Observation of interdigitated lamellar structures driven by anion-cation interactions.
• Enantiotropic liquid crystalline phases observed over a wide temperature range.
• Several complexes exhibit melting points below 100°C, with two being liquid at room temperature.

Conclusions:

• A new family of fluorinated ionic liquid crystals has been developed.
• The study demonstrates the utility of halogen bonding in designing functional supramolecular materials.
• These materials hold promise for applications requiring tunable liquid crystalline behavior.