Reversible Visible-Light Tuning of Self-Organized Helical Superstructures Enabled by Unprecedented Light-Driven Axially Chiral Molecular Switches

Two enantiomeric light-driven azo molecular switches with axial chirality and extended conjugation were found to exhibit unprecedented reversible photo-isomerization in both organic-solvent and liquid-crystal media only upon visible-light irradiation. When doped in an achiral liquid crystal with a different concentration, the chiral switch was able either to immediately induce an optically tunable helical superstructure or to retain an achiral liquid-crystal phase whose helical superstructure was induced and tuned reversibly upon visible-light irradiation. Furthermore, reversible dynamic red, green, and blue reflection achieved only by using visible light was demonstrated.