Design, Synthesis And Self-assembly Of Thiophene(Triazole)-based Triazine Wedge- Shape And Dimer-like Polycatenar Liquid Crystal Compounds

Liquid crystal combines both periodic order of crystal and mobility of liquid at the molecular level, which has led to the liquid crystalline system have stimulate responsiveness, the self-healing and adaptability, therefore study on how the liquid crystalline molecules self-assembly into supramolecular structure in spatial is one of the most important subjects of scientific research today. In the research of supramolecular liquid crystal, we can obtain the profound understanding on the order and complexity in soft matter self-assembly system and the understanding of the fundamental principles of self-assembly, which will guide the other multifunctional materials in the field of self-assembly synthsis and performance study.This thesis is composed of three chapters. The first chapter and the second chapter introduce the synthesis and liquid crystalline behavior research of the thiophene (triazole)-based 4,6-diamino-1,3,5-triazine wedge-shape molecules and dimer-like bent-core Polycatenar liquid crystal compounds respectively; the third chapter is the experimental part.In chapter 1, four types of liquid crystalline molecules containing 1,3,5-triazine group are designed and synthesized. Intramolecular or intermolecular hydrogen bonds which has a very important role in the self-assembly of supramolecular is easily formed in the 1,3,5-triazine. Due to the special nature of the triazine, it makes widespread concern in many areas. Coltex/p6mm-Colrec/c2mm-Colhex/p6mm phase sequence is observed along with the increasing of the alkyl chain n in the 1T2/n (n=10,12,14,16) series. In the 1T6/n (n=12,16) series, along with the increasing of the n, the phase sequence CubI/Im3m-CubI/Pm3n is opposite to the sequences observed previously; Amazingly, although the compounds 2T3/14 and 1Tr3/14 has similar molecular structure and shape, they form entirely different liquid crystalline phases. Compound 2T3/14 shows a Colhex/p6mm, but three-dimensional structure CubI/Pm3n is observed in the compound 1Tr3/14. In addition, the fluorescence emission spectrum test shows that compound 1T2/12 has a strong ability to recognize Cr3+, Cu2+, Fe3+, Hg2+, Pb2+. This has potential applications in fluorescent tags and molecular fluorescent probe field etc.In chapter 2, bend-core Polycatenar liquid crystalline molecules IC6/n、ⅡE6/n、 Ⅲ12/n and Ⅳs12/n are described. Because of the particular shape of these bend-core molecules, it gives rise to a macroscopic polarization in the smectic layers or columns. The singularities of these self-organizing supramolecular systems have attracted the attention of academics. These bent-core molecules can form versatile intermediate phases, such as columnar phases typical for disc-like molecules, smectic and nematic phases, typical for rod-like molecules, also can form many specific phases not observed for other groups of mesogens. Even if non-chiral bent-core molecules, it can also organize into chiral structures, and form sponge phases or twisted nematic phases. Rarely, bent-core molecules can also form complex three-dimensional structure, with cubic or tetragonal symmetry. In this chapter, the research finds that in series of IC6/n (n =10,12,14,16), with the increase of n, Colhex/p6mm-CubVes/Pm3n phase sequence is observed. By changing the connection group X, core and center elbow, the effect of molecular structure on the liquid crystalline behavior was studied. The gelation abilities of compounds IC6/14, Ⅲ12/12 and Ⅳs12/12 are examined in various organic solvents. The thermoreversible physical gels formed with low molecular weight organic molecules may have potential applications in many areas, such as hardeners of solvents, drug delivery systems, membranes, and sensors and so on.The third chapter is the experimental section including the synthetic route and spectral data.