Bent-shaped liquid crystal dimers. Influence of the direction of the oxybiphenylenecarboxyl groups on their mesomorphic behavior

In order to study what role the direction of the whole mesogenic groups play on their mesomorphic behavior we synthesized a series of bent-shaped dimers in which the mesogens differ in their relative orientation along the long molecular axis of the dimers. A tilted anticlinic smectic mesophase is presented exclusively by the dimer where the mesogens are tethered in a head-to-head fashion. The head-to-tail and tail-to-tail organizations of the mesogens preclude any kind of mesophase formation. The mesomorphic behavior of dimers was characterized by a combination of polarizing optical microscopy, differential scanning calorimetry and computational techniques.