Azobenzene‐Based Glycomacrocycles: Synthesis, Photoisomerization, and Photomodulation of Liquid Crystal Helical Pitch with Helix Inversion

Novel azobenzene-embedded glycomacrolactones bearing different substituents on the glucopyranoside ring have been synthesized and characterized by NMR spectroscopy, UV/vis spectroscopy, and circular dichroism (CD), then applied for cholesteric liquid crystal photomodulation. All the macrocycles displayed good photochromic properties, fatigue resistance, thermal bistability, and chiroptical activity. As chiral dopants for nematic liquid crystal (NLC), an amplification of helix upon E to Z photoisomerization and enforcement of helical twisting power (HTP) at Z-rich state have been observed. We also demonstrated the critical influence of sugar-ring functionalization in governing chirality transfer and photoswitching behavior in cholesteric liquid crystals (CLCs). Two of the synthesized glycomacrocycles uniquely achieved photoinduced helix inversion-marking the first such example for this class of compounds.