Frustrated smectic layer structures in bent-shaped dimer liquid crystals studied by x-ray microbeam diffraction.

The layer structures in bent-shaped liquid crystal dimers mOAM5AMOm (m=6-16) have been investigated by x-ray microbeam diffraction. These liquid crystal molecules have two rodlike mesogens connected with an odd-numbered alkylene spacer and form a bent shape. In these compounds it is found that the structure changes from the single (m=6) to frustrated-layer structures (m=8, 10, and 12) and switchable frustrated-layer structures (m=14 and 16) with increasing terminal chain length. An anticlinic antiferroelectric structure is suggested in the compound with m=16, based on the different electric-field-induced reorientation behavior from those in the other dimers.