Unusual molecular diffusion in an induced SMA phase composed of charge-transferred liquid crystalline mixtures

We investigated molecular diffusion in charge-transferred (CT) liquid crystalline (LC) mixtures composed of a cyanobiphenyl compound (8CB, electron acceptor) and an azobenzene derivative (7AB7, electron donor). When the molar ratio of 7AB7 is as small as 0–0.1, the mixture forms a uniform two-dimensional (2D) fluid phase called induced SmA. Statistically, the induced SmA phase possesses the same structure as pure 8CB, but in the dynamics, it shows unusual molecular diffusion. With hemispherical bubbles made of the induced SmA phase, we examined gas transport across the films, and found that the oxygen diffusion abruptly fell when the 7AB7 ratio exceeded 0.05. The result suggests that even in the macroscopically uniform 2D fluid phase, small CT crystalline domains can be formed and stably dispersed, which should disturb the one-dimensional molecular transport normal to the smectic layer.