Insight into the mesogenic character of 15-membered triolefinic azamacrocycles, and their diolefinic open precursors and Pd(0) complexes

The mesogenic ability of triolefinic 15-membered azamacrocycles, appropriately functionalised with arenesulfonamide groups, as well as their open precursors and palladium(0) complexes, has been explored. The double bonds increase the rigidity of the macrocycle and are also responsible for the coordination to the metal. These features, along with the substitution pattern of the aryl units, determine the mesomorphic behaviour of the compounds. For example, a smectic mesophase was observed for the macrocycle derived from 4-hexadecyloxybenzenesulfonamides. In contrast, columnar mesophases appear for derivatives that incorporate 3,4-dialkoxybenzenesulfonamides. All of the mesophases were studied by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction, which enabled the determination of the structural parameters. © The Royal Society of Chemistry 2005.