Supramolecular discotic liquid crystals from wedge‐shaped diacetylenes and their polymerization

Wedge‐shaped diacetylenic compounds were synthesized by the amidation reaction between the linear diacetylenic side groups and 5‐acetamidoisophthalic acid. The compounds showed enantiotropic transitions. In the liquid‐crystalline states, they were dimerized via hydrogen bonding of acetamide groups, forming disklike supramolecules and had rectangular columnar phases. Polymerization was carried out by UV irradiation and thermal annealing at their mesophase temperatures, giving polydiacetylenes. After polymerization, the compounds became dark red, but their textures were still birefringent. The IR and ultraviolet–visible study demonstrated that the polymerization proceeded topochemically by 1,4‐addition. X‐ray analysis showed that the UV‐polymerized samples maintained rectangular columnar phases.