A new class of bent‐shaped mesogens exhibiting unusual mesophase behaviour

Examples of a new class of bent-core compounds are presented, the central fragment of which consists of a benzoyl derivative of a secondary cyclic amine. The mesophase behaviour has been studied by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction and electro-optical measurements. It was found that the five-ring compounds form smectic CP or B1 phases which are typical for bent-core mesogens. The six-ring compounds exhibit, in some cases, only conventional non-polar smectic phases; in other cases non-polar smectic phases as well as banana phases are seen. Of particular interest is the occurrence of a switchable uniaxial semectic A-like phase with an antiferroelectric structure.