Synthesis and mesomorphic properties of three-benzene-ring-containing banana-shaped liquid crystals

A homologous series of three-benzene-ring-containing banana-shaped compounds, N,N-bis(4-alkylcarbonyloxybenzylidene)benzene-1,3-diamine, were synthesised by esterifying aliphatic acids with the three-benzene-ring bent core 1,3-phenylene-bis(4-hydroxybenzylideneamine). As the number of carbon atoms in the aliphatic acids increased from 1 to 12, 12 novel banana-shaped compounds resulted with increasing lengths in their terminal tails. The mesomorphic properties of this homologous series of three-benzene-ring-containing banana-shaped compounds were characterised by means of polarised optical microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical studies. Our results have demonstrated that this series of banana-shaped compounds can form mesophases, although each of their bent cores contains only three benzene rings.