Non-symmetric liquid crystal dimer containing a carbohydrate-based moiety

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Liquid Crystals

Background:

• Liquid crystal dimers offer unique self-assembly properties.
• Understanding phase transitions in complex molecular systems is crucial.
• Non-symmetric structures can lead to novel mesophases.

Purpose of the Study:

• To synthesize and characterize a novel non-symmetric liquid crystal dimer.
• To investigate the phase behavior, specifically glassy and smectic A phases.
• To elucidate the role of hydrogen bonding and van der Waals interactions in phase transitions.

Main Methods:

• Synthesis of 1-[3-O-(D-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4'-oxy)]octane.
• Variable temperature infrared spectroscopy.
• Differential scanning calorimetry (DSC) for thermal analysis.

Main Results:

• The synthesized dimer exhibits glassy behavior and a highly interdigitated smectic A phase.
• Aromatic and alkyl fragments show significant overlap within the smectic A phase.
• Infrared spectroscopy indicated no significant change in hydrogen bonding at the glass transition or smectic A-isotropic transition.

Conclusions:

• The smectic A-isotropic transition is primarily driven by van der Waals interactions.
• Hydrogen-bonded aggregates persist into the isotropic phase.
• The study provides insights into the molecular mechanisms governing liquid crystal phase transitions.