Hexaarylbiimidazoles(HABI)-functionalized lyotropic liquid crystalline systems as visible light-responsive materials

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Hexaarylbiimidazoles (HABIs) are photoswitchable molecules with limited literature.
• HABI1 exhibits negative photochromism and green light responsiveness.
• Controlling lyotropic liquid crystalline (LLC) material structure with light is an emerging area.

Purpose of the Study:

• To investigate HABIs as photo-responsive actuators for LLC materials.
• To synthesize and characterize HABI1 and HABI2 for LLC applications.
• To explore light-induced phase transitions in lipid-based systems.

Main Methods:

• Synthesis of HABI1 (methyl chains) and HABI2 (dodecyl chains).
• Time-resolved small-angle X-ray scattering (TR-SAXS) to study LLC nanostructure.
• Irradiation studies to observe HABI isomerization and LLC phase behavior.

Main Results:

• HABIs showed rapid isomerization under light and slow reversion in the dark, indicating stability.
• HABIs induced complete phase transitions in phytantriol-based LLCs.
• HABI2 caused greater disruption of lipid packing than HABI1.
• Light triggered transitions from lamellar to bicontinuous cubic phases, altering release profiles.

Conclusions:

• HABIs are effective photo-responsive actuators for LLC materials.
• The study demonstrates potential for light-controlled "on demand" drug delivery.
• Tuning HABI structure and lipid composition allows for controlled release kinetics.