New heterocyclic analogs of BCH- and CBC-compounds

A series of new liquid crystalline compounds with BCH- and CBC- structures was synthesized. They differ from the known carbocyclic analogs by the 1,2, 4-oxadiazole fragment placed in various positions of the long mesomorphic m olecule. The cross-coupling reaction of the aromatic boric acids and bromid es is a new way for mesogenic heterocycles design. The transition temperatu res of these new liquid crystals are lower as compared with carbocyclic BCH - and CBC- analogs and significantly depend on the position of the nonlinea r heterocyclic unit in the molecular chain.