ABSTRACT

Nine new C₃-symmetric 2,7,12-tris(decanoxy)-3,8,13-tris(alkoxy)truxene discogens were synthesized, and all exhibited only one three-dimensionally ordered hexagonal columnar mesophase with a wide mesogenic temperature range, as characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffractometry. Crucially, as the length of the alkoxy chain increased, the melting points first increased and then decreased, and, at the same time, the temperatures of the clearing point decreased gradually. In addition, these compounds were found to be highly thermally stable, having decomposition temperatures occurring well above 350°C, as determined by thermogravimetric analysis. The self-assembly behaviors in solution were studied using variable-concentration ¹H-NMR, revealing that the truxenes self-aggregated in solution via the π–π facial interactions of the polycyclic aromatic units, and scanning tunneling microscopy results revealed that one of the discotic liquid crystal compounds periodically assembled in a hexagonal geometry at the liquid–solid interface of highly oriented pyrolytic graphite.

摘要

合成了九个新的 C ₃ -对称 2,7,12-三(癸氧基)-3,8,13-三(烷氧基)杜克烯disogens，均仅表现出一种具有宽介晶温度范围的三维有序六方柱状中间相，如偏光光学显微镜、差示扫描量热法和 X 射线衍射法所表征。至关重要的是，随着烷氧基链长度的增加，熔点先升高后降低，同时透明点的温度逐渐降低。此外，发现这些化合物具有高度的热稳定性，通过热重分析确定其分解温度远高于 350°C。^{使用可变浓度1}研究溶液中的自组装行为H-NMR，揭示了通过多环芳族单元的 π-π 面相互作用在溶液中自聚集的 truxenes，以及扫描隧道显微镜结果表明，其中一种盘状液晶化合物在液体中周期性地组装成六边形几何形状——高取向热解石墨的固体界面。