Helical superstructures in a novel smectic mesophase formed by achiral banana-shaped molecules

A new smectic type mesophase without in-plane order is presented which is f ormed by nitro substituted banana-shaped compounds. The structure of this p hase is not yet known in detail. The growth of germs and also the textures point to a helicoidal structure. The helical structure is obviously the res ult of the chirality of the smectic layers which is caused by the tilt of t he molecules together with the polar arrangement of the angled molecules.