Synthesis and Liquid-Crystal Behavior of a Novel Class of Disklike Metallomesogens: Hexasubstituted Triazolehemiporphyrazines

Abstract

The synthesis, characterization and mesomorphic properties of two series of new discotic molecules based on the triazolehemiporphyrazine core is described. This central unit has been attached to six lipophilic chains, two dodecyl groups on the triazole ring and four dodecyloxy or dioctylaminocarbonilmethoxy on the isoindole moiety, and metallic complexes (Cu, Ni) have been prepared. The mesogenic behavior has been studied using optical microscopy, DSC, and X-ray diffraction. The alkoxy-substituted macrocycles melt from the solid to the liquid-crystalline phase at relatively low temperatures (ca. 30 °C), exhibiting hexagonal columnar mesophases (Dho) (despite being elliptical molecules) in a large temperature range, up to 300 °C in the case of metallic complexes. The dialkylamide derivatives are not mesogenic despite the extent of the paraffinic part. This fact is probably due to the steric hindrance between the branched chains, thus difficulting columnar stacking of the cores.