Nitrogen-rich pi-conjugated stars - discotic liquid crystals with an electron deficient core

新型盘状液晶具有宽的中间相、高的电子亲和力、高效的荧光和传感能力。缺乏电子的杂环、吡嗪、1，3，5-三嗪、1，2，4-三氮唑和1，3，4-恶二唑是这些星形或盘状分子中心的基石。一系列的烷基链以乙醚、胺或硫醚的形式连接到恒星的边缘，以提供溶解性和熔融性。链的数目、位置、类型和长度是调节热性质的工具；聚集态的pi-链段产生柱状物，它们的脂肪表面应该导致宽广的中间相。N，O，S是中等到强的给电子基，从而改变了光学性质。研究了晶相、浓度、极性和质子对光谱和非线性光学性质的影响。将使用热方法来表征相行为，用X射线衍射法来阐明LC相的结构。作为潜在的新型n型半导体和有机发光二极管的发射体，将进行电学研究。一些恒星将作为反应的底物，将芳烃碎片转化为环状杂环系统。Cadogan反应将邻-硝基联芳基还原为杂化的咔唑，1，2-二芳基芳烃在Scholl反应中被氧化，氧化光环化反应将邻位的二芳基芳烃转化为扩展的稠合杂环芳烃体系。S-七津，一种独特的荧光团，将作为Hekates的新核心引入。

New discotic liquid crystals displaying broad mesophases, high electron affinity, efficient fluorescence and sensing ability will be synthesized. Electron deficient heterocycles, pyrazine, 1,3,5-triazine, 1,2,4-triazole and 1,3,4-oxadiazole are building blocks for the center of these star- or disc-shaped molecules. A series of alkyl chains is attached as ether, amine or thioether to the rim of the stars to provide solubility and fusibility. Number, position, type and length of the chains are tools to tune the thermal properties; aggregation of pi-segments yields columns and their aliphatic surface should result in broad mesophases. N,O,S are moderate to strong electron donating groups, thus modifying the optical properties. The impact of phase, concentration, polarity and protons on optical spectra as well as non-linear optical properties will be studied. Thermal methods will be used to characterize phase behavior, X-ray diffraction to elucidate structures of the LC-phases. As potential new n-type semiconductors and emitters in OLEDs, electrical studies will be performed. Some stars will be substrates for reactions converting arylene fragments to annulated heterocyclic systems. Cadogan reaction reduces o-nitrobiaryl units to heteroanalogous carbazoles, 1,2-diarylarenes will be oxidized in a Scholl reaction and oxidative photocyclisation transforms vicinal distyrylarenes to extended condensed heterocyclic aromatic systems. s-Heptazine, a unique fluorophore, will be introduced as a new core for hekates.