Mesomorphic 1,2,4-triazine-4-oxides in the synthesis of new heterocyclic liquid crystals

New liquid-crystalline materials are described, which are obtained using a versatile synthetic methodology that employs the intermediacy of 1,2,4-triazines. Triazines, triazine-N-oxides, pyridine and laterally cyanated pyridines are among the compounds reported and the mesomorphism of the different structures shows how function affects mesomorphism. In particular, systems based on laterally cyanated pyridines turn out to be materials with low melting points and wide phase ranges. Lateral dipole moments, calculated at the Hartree-Fock level for the triazine-N-oxides and the cyanopyridines, showed a significant dependence on conformation and confirmed that the dipole moment was great for the latter materials. Appreciable spontaneous polarisation was measured for chiral derivatives of the triazine-N-oxides.