The Effect of the Substituent Positions on Self-Assembly Behaviors of Liquid-Crystalline 1,3,4,6,9b-Pentaazaphenalene Derivatives

Abstract

Abstract We describe the syntheses and phase transition behaviors of liquid crystals composed of triangular π-conjugated molecules, 1,3,4,6,9b-pentaazaphenalene (5AP). Three types of 5AP derivatives having 3,4,5-tris(dodecyloxy)phenyl ((OC12)3Ph) were prepared by changing substituent positions. From thermal and structural analyses, liquid crystalline phases were observed from all derivatives. According to structural data and phase transition behaviors, it was suggested that the positions of the substituents significantly influence molecular alignments in liquid crystals as well as thermal properties. In particular, the columnar structures, which are favorable for expressing efficient carrier transportation, were observed in the 5AP derivative. These results suggest that the 5AP scaffold could be a platform for constructing a variety of aggregated structures by slightly different patterns of the molecular structures. Plausible models for these transitions are discussed.