Main-chain Liquid Crystal Polymer Crown Ether Ligands And Their Complexes

The dissertation consists of four parts.1 The progress made in this field and the idea of our workThe concepts of liquid crystal, crown ether, liquid crystal crown ether and liquidcrystalline polymers were introduced. The progress made in this field and the assumption of our work were also introduced.2. Synthesis and characterization of main-chain liquid crystalline polymers crown ether ligands with dibenzo-18 -crown-6 crown ether cycleStarting from the molecular design, a novel kind of main chain liquid crystalline polymers crown ether ligands with biphenyly-type mesogenic unit and crown ether cycle of cis(trans)-4, 4 ' -bis(4-hydroxyphenyl-azo)diben- zo-18-crown-6 was synthesized via solution condensation polymerization from 4,4 ' -(α,ω-alkylene dioylxy) dibiphenylyloyl dichloride, cis(trans)-4, 4-bis(4-hydroxyphenyl-azo)dibenzo-18-crown-6, and 1,10-decandiol,which can be divided into two series according to configuration of the compound. The structures are shown as follows:3. Synthesis and characterization of main-chain liquid crystalline polymers crown ether complexes with dibenzo-18 -crown-6 crown ether cycleCP-IA～CP-ID and CP-IIA～CP-IID used as ligands, complex with K⁺ and Zn²⁺ ion respectively, a new kind of main chain liquid crystalline polymers crown ether complexes was therefore synthesized, which can be divided into two series, 16 complexes according to configuration and metal ion of the compound.4. ConclusionThe structures of the intermediates, monomers, the ligands and their complexes were characterizeded by means of Elemental Analysis, IR, UV-Vis, ¹H NMR and AAS. IR, the polarizing optical microscopy (POM), differential scanning calorimetry(DSC) and wide angle X-ray diffraction(WAXD) were applied to identify the mesophase of the intermediates, monomers, the ligands and their complexes.The intermediates, monomers , ligands and their complexes which have liquid crystalline properties were characterized by means of IR, differential scanning calorimetry(DSC), [η] ,UV-Vis, the polarizing optical microscopy (POM), and wide angle X-ray diffraction(WAXD).The synthesis procedure is optimized and improved. Some key techniques and thorny problems about the chose of solvents, the purification and separation of products are solved. The influence on liquid crystalline properties of a novel kind of main chain liquid crystalline polymers crown ether ligands and complexes have been invested systematically and some regular results were obtained.Experimental results have shown that:(1) The compounds 1, 2, CP-I, CP-II, CP-IK, CP-IIK, CP-IZn and CP-IIZn are thermotropic liquid crystal.(2) It was found that all the compounds went into liquid-crystal phase when they were heated over their melting temperature (T_m). The thread texture, ball granul texture and schlieren texture can be observed.(3) The ligands ,potassium complexes and zinc complexes exhibited a UV absorption band withλ_max located between 368.0～371.5 nm , 354.0～367.0nm and 360.5～365.5nm separatelly . After complexation, the position of absorbance maximum shifts to shorter wavelengths.(4) Metal ions complex with the crown ether ring of the ligands, but don't complex with -N=N- of the ligands.(5) Both T_m and T_i decrease with the the length of flexible spacers unit in the ligands, the temperature range of the liquid crystal phase of the ligands becomes wide. The T_m and T_i of CP-II are higher than CP-I.(6) The T_m and T_i of trans-configuration complexes are higher than cis--configuration complexes.For complexes of the same configuration, both T_m and T_i decrease with the increase of the length of flexible spacers unit , the T_m and T_i of ligands are higher than complexes. The temperature range of the liquid crystal phase of the complexes becomes wide.