Dual-Regulation of Supramolecular Chirality in Achiral Side-Chain Azobenzene Liquid-Crystalline Polymers

Azobenzene (Azo) liquid-crystalline polymers are intriguing due to their unique photo-induced isomerization and supramolecular chirality. However, clarification on multicomponent chiral induction towards Azo polymers remains ambiguous and challenging. Herein, chiral solvents and amines were employed to control the chiroptical activity of achiral Azo polymers. Methyl L-/D-lactate was added as the poor solvent and chiral inducer to achieve the first chiral induction in Azo aggregates. Chiral amines were utilized for the second chiral induction based on the acid-base interactions between the carboxyl groups of polymers and amines. The chiral enhancement and inversion of Azo units could be observed through the synergistic or antagonistic effect between solvents and amines. The impacts of solvent, chemical structures, feed ratio, enantiomeric excess, and temperature on supramolecular chirality were systematically studied. Furthermore, this system displayed the chiroptical switching property and chiral recovery under reversible irradiation. By virtue of chiral solvents and amines, hierarchical regulation of supramolecular chirality in achiral azobenzene liquid-crystalline polymers was carried out. Chiral enhancement and inversion were accomplished in one system based on the synergistic or antagonistic effect between different chiral inducers.image