本文先朝個別合成Schiff base與quinoxaline兩種結構之液晶化合物前進，兩方面皆藉由改變不同官能基，觀察其液晶行為與單晶數據之中作用力類型的關聯性，並進一步合成同時具有Schiff base與quinoxaline結構之化合物8-12以探討兩者同時存在時的作用力差異。 以Schiff base為主體之化合物1-4，藉由不同間隔基團，可控制分子間CH-π數量的多寡以調整分子排列情形，最後產生對應之液晶相。另一方面，quinoxaline為主體之化合物5-7則呈現出強弱氫鍵對於此系列化合物的影響，值得一提的是，分子形狀在前半部的兩個系列之中亦為影響液晶行為的重要因素。 本文後半部敘述之Schiff base與quinoxaline複合材料擁有寬廣的液晶相範圍。此外，利用粉末X光繞射數據與變溫紅外光光譜可判斷其排列方式之轉換與氫鍵的存在與否息息相關，於本系列之中，強氫鍵並不利於穩定化合物5-12的液晶相，而趨向以弱氫鍵連結彼此的方式來主導分子之間的排列。 ;In this study, three series of Schiff base and quinoxaline derivatives were synthesized. Different types of rigid spacer were incorporated with Schiff base in order to investigate the spacer effect. Schiff base derivatives 1-4 were synthesized and compounds 1-2 showed long range mesogenic phase as nematic, smectic A and smectic C phases. The corelation between interactions and mesophases of compound 1 (n = 3, 6)and 2 (n = 3) were rationalized by the assistance of single crystal X-ray diffraction data. Crystallographic data indicated that the better mesomorphic properties might be controlled by CH-π, π-π and H-bonds in such system. On the other hand, quinoxaline derivatives 5-7 were synthesized and single crystallographic data of 7 (n = 6) were collected. The variable temperature FT-IR spectra and single crystallographic data illustrated the importance of weak H-bond of mesogenic behavior in quinoxaline derivatives. The existence of strong H-bond by carboxyl group not only shortened the range of mesogenic phases but also raised the clearing temperature. In last two chapters, compound 8-12 were synthesized as quinoxaline-Schiff base complex and showed wide temperature range of smectic or columnar phases. With changing the molecular interactions and/or suitable aspect ratios, these quinoxaline-Schiff base derivatives were proven as promising materials for further study.
