Azobenzene/Triptycene-Based Cholesteric Liquid Crystal Dopants

Area of Science:

• Materials Science
• Organic Chemistry
• Physical Chemistry

Background:

• Cholesteric liquid crystals (CLCs) exhibit structural color tunable by chiral dopants.
• The precise interactions between CLCs and dopants, and chiral information transfer, remain incompletely understood.

Purpose of the Study:

• To investigate the structure-property relationships of photoswitchable chiral dopants for CLCs.
• To elucidate the mechanisms of chiral information transfer from dopants to CLCs.

Main Methods:

• Synthesized and characterized five chiral dopants featuring a triptycene core and azobenzene switchable unit.
• Performed structure-property analysis to correlate dopant structure with helical twisting power (β).
• Investigated the impact of E/Z photoisomerization of azobenzene on β values.

Main Results:

• Triptycene-azobenzene dopants demonstrated high helical twisting power (β) values up to 127 µm⁻¹.
• Dispersion interactions and electron-deficient aromatic units were identified as key factors influencing β.
• Significant changes in β upon E/Z photoswitching were observed.

Conclusions:

• The triptycene-azobenzene system effectively transfers chiral information to CLCs.
• Photoswitchable dopants enable the development of multicolor, high-contrast liquid crystal films.
• Understanding these interactions allows for precise control over optical properties across UV to IR ranges.