Molecular Crystals and Liquid Crystals, Vol.494, 282-292, 2008
Synthesis and Physico-Chemical Properties of Polar Liquid Crystal Materials Incorporating a Coumarin Skeleton at the Terminal Position
This paper described the synthesis and physico-chemical properties of homologous series of 2-oxo-2H-chromen-6-yl 6-alkoxy-naphthalene-2-carboxylate (compounds 1-n). Compounds 1-n show a monotropic nematic (N) phase, where the average of the N-isotropic (1) phase transition temperatures is ca. 140 degrees C. The mesomorphic properties were also examined by binary phase diagrams for the mixture of 1-n (n = 4 or 8) and 4-(cyano-4'-octyloxybiphenyl (8 OCB), or 4-heptyloxyphenyl 4-nonyloxybenzoate. The physico-chemical properties for compounds 1-n are compared with the corresponding 4-alkoxybenzoate derivatives (compounds 2-n) and 4-alkoxybiphenyl-4'-carboxylate ones (compounds 3-n). These results are discussed in terms of molecular structures and the electrostatic natures of the molecules.