Abstract
We present a simple synthetic strategy leading to nonsymmetrical functionalized hexasubstituted triphenylene. Further, new β-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 β-position of pentakis(alkoxy)triphenylenes stabilized the intra- or intermolecular interaction between the cores to form columnar mesophases.
Acknowledgment
S. K. Varshney is grateful to Prof. K. A. Suresh for his sustaining support for the research work and to Dr. Veena Prasad for the fruitful discussions. A fellowship by the Japan Society for Promoting Science (JSPS), Tokyo, Japan, is gratefully acknowledged.
Notes
Cr = crystal; Colh = columnar hexagonal; Colhp = columnar hexagonal plastic; g = glassy transition; I = isotropic liquid.
Temperatures are given in °C and enthalpies (in parentheses) are given in kJ mol−1.