Chirality Induced by Circularly Polarized Light in Liquid Crystalline Twin Dimers with Azo Linkages

Emergence of large circular dichroism (CD) was found in liquid crystal twin dimers with azo linkages, nOAZmAZOn. The compounds with even m are of rod-shape and show the SmA phase, whereas those with odd m are of bent-shape and show the SmCA and BX phases. Right- and left-circular polarized light (CPL) irradiation in the crystal and BX phases induces positive and negative CD, respectively. However, large CD with the opposite sign is induced by decreasing temperature from SmCA to BX under CPL irradiation. Two different mechanisms were discussed.