Amide, urea and thiourea-containing triphenylene derivatives: influence of H-bonding on mesomorphic properties

The synthesis and thermotropic properties are reported for a series of hexaalkoxytriphenylenes that contain an amide, urea or thiourea group in one of their alkoxy tails. The intermolecular hydrogen bonding abilities of these molecules have a disturbing influence on the formation and stability of the columnar liquid crystalline phases. The stronger the hydrogen bonding the more the liquid crystallinity is suppressed, probably due to disturbance of the - stacking of the triphenylene discs. As a direct result, urea- and amide-containing triphenylene derivatives are not liquid crystalline, but several thiourea derivatives show hexagonal columnar mesophases.