Sheet-shaped mesogens based on 1,3,5-triazines: variation of columnar mesophases through intermolecular hydrogen bonding

The mesomorphic behaviour of a liquid crystalline sheet-shaped 2,4,6-triarylamino-1,3,5-triazine bearing six peripheral decyloxy chains has been investigated in binary mixtures with two-fold alkoxy substituted non-mesomorphic benzoic acids. Each investigated equimolar mixture exhibits an enantiotropic columnar phase with either a hexagonal or a rectangular lattice. The two-dimensional lattice parameters depend on the length and positions of the flexible alkoxy chains of the aromatic carboxylic acids. The structure formation of the mixed systems giving rise to variations of the mesophase structure of the pure triarylaminotriazine results from intermolecular hydrogen bonding between the complementary melamine and acid components.