Synthesis and Liquid-Crystalline Properties of β-Bromopentakis(Alkoxy) Triphenylene: Reactivity of VOCl<sub>3</sub>, MoCl<sub>5</sub>, and FeCl<sub>3</sub>as Oxidants
作者:Sanjay Kumar Varshney、Hiroki Nagayama、D. S. Shankar Rao、Hideo Takezoe
DOI:10.1080/15421406.2010.504514
日期:2010.10.14
We present a simple synthetic strategy leading to nonsymmetrical functionalized hexasubstituted triphenylene. Further, new -bromopentakis(alkoxy)triphenylene was synthesized applying this strategy and reactivity of oxidizing agents such as VOCl3, MoCl5, and FeCl3 was investigated. The liquid-crystalline properties were studied by polarizing optical microscope (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies. The higher homologues exhibit a columnar hexagonal (Colh) phase, whereas lower homologues also exhibit a columnar hexagonal plastic (Colhp) phase. These mesophases are stable below and above the ambient temperature. We studied the effect of polar substitution on molecular self-assembly and found that a bromo bulky substituent at the -position of pentakis(alkoxy)triphenylenes stabilized the intra- or intermolecular interaction between the cores to form columnar mesophases.