Ionic liquid crystals based on mesitylene-containing bis- and trisimidazolium salts

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Ionic liquid crystals (ILCs) are a fascinating class of materials combining ionic liquid properties with liquid crystalline behavior.
• Imidazolium-based salts are versatile building blocks for designing functional materials.
• Understanding the relationship between molecular structure and mesomorphic properties is crucial for developing new ILCs.

Purpose of the Study:

• To synthesize novel bis- and trisimidazolium-based ionic liquid crystals.
• To investigate the mesomorphic properties and phase transitions of these new ILCs.
• To explore the self-aggregation behavior of imidazolium salts in solution.

Main Methods:

• Synthesis of bis- and trisimidazolium salts with hexadecyl chains and a mesitylene linker.
• Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) for mesophase characterization.
• Powder X-ray diffraction (p-XRD) for structural analysis as a function of temperature.
• Diffusion Nuclear Magnetic Resonance (NMR) spectroscopy to study self-aggregation in solution.

Main Results:

• Successful synthesis of novel bis- and trisimidazolium salts.
• Characterization of the Smectic A phase in the synthesized ILCs.
• Observation of a glass transition from Smectic A to a metastable lamellar phase upon cooling via p-XRD.
• Demonstration of self-aggregate formation in solution for bisimidazolium iodide.

Conclusions:

• The synthesized imidazolium-based ILCs exhibit tunable mesomorphic properties.
• The compounds display a reversible glass transition, indicating potential for thermochromic or memory devices.
• The ability to form self-aggregates opens avenues for applications in nanotechnology and drug delivery systems.