2-Octyl thiophene based three ring mesogens: solid state (13)C NMR and XRD investigations.

Area of Science:

• Materials Science
• Organic Chemistry
• Liquid Crystals

Background:

• 2-Octyl thiophene derivatives are explored for their liquid crystalline properties.
• Understanding structure-property relationships in mesogens is crucial for advanced materials.
• Direct arylation offers an efficient synthetic route for complex organic molecules.

Purpose of the Study:

• To synthesize and characterize novel three-ring mesogens based on 2-octyl thiophene.
• To investigate the influence of alkoxy chain length on mesomorphic behavior.
• To elucidate the phase behavior and molecular ordering using advanced techniques.

Main Methods:

• Palladium acetate-catalyzed direct arylation for synthesis.
• Hot-stage optical microscopy and differential scanning calorimetry for phase analysis.
• Variable temperature powder X-ray diffraction for phase confirmation.
• High-resolution solid-state Carbon-13 Nuclear Magnetic Resonance (NMR) spectroscopy for molecular ordering.

Main Results:

• Enantiotropic polymesomorphism, including nematic, smectic A, C, and B phases, observed across homologs.
• Smectic B phase formation confirmed by sharp X-ray diffraction peaks.
• Thiophene ring exhibits higher orientational order than phenyl rings in all mesophases.
• Photoemission observed at approximately 410 nm in chloroform solution.

Conclusions:

• The synthesized 2-octyl thiophene benzoates display complex liquid crystalline behavior.
• Molecular shape, particularly the terminal bend, influences orientational order.
• These mesogens possess photoemissive properties, suggesting potential optoelectronic applications.