3,4-Dialkoxybenzoyl substituted derivatives of hexahydro-1,3,5-triazine with hexagonal columnar mesophases

The synthesis of a homologous series of amidic derivatives of azacyclic compounds, i.e. 3,4-dialkoxybenzoyl ('two chain') N',N',N'-substituted hexahydro-1,3,5-triazines with alkoxy chains-OCnH2n+1 having n = 5, 6, 8-14 and 16 carbon atoms, and of one corresponding amine derivative, i.e. 1,3,5-tris(3,4-didecyloxybenzyl)hexahydro-1,3,5-triazine, is described. The thermal behaviour of the compounds is characterized by means of polarizing microscopy and differential scanning calorimetry. The amide with n = 6 is a monotropic liquid crystalline material, whereas the amides with n = 8-14 and 16 exhibit enantiotropic mesomorphism. The amine derivative with n = 10 is not a thermotropic liquid crystalline compound. The optical textures of the mesogenic compounds are spherulitic. X-ray diffraction measurements for the amides with n = 8, 10, 12, 13 and 16 show evidence of a hexagonal columnar structure (Colh) in the mesophase. The lattice constants of the mesophase are compared with the values from CPK models.