Development of New Fluorine-containing Ferroelectric Liquid Crystals

本项目的目的是开发一种新的高效的光学活性有机氟化合物的合成方法，并利用这些化合物作为手性构建块来开发新型铁电液晶。首先，东京工业大学研究小组开发了新的三氟硅烷介导的Claisen重排过程，并成功地将该Claisen过程应用于α-氟-α-甲基和α-氟-α-三氟甲基羧酸衍生物的不对称合成。特别有趣的是，用氟化衬底观察到的不对称透射感与用非氟化衬底观察到的不对称透射感相反。其次，日本能源株式会社利用光学活性氟化合物作为手性构建块制备了各种液晶，并评价了它们作为铁电液晶的功能性质。值得注意的发现是：(1)含氟液晶比一般非含氟液晶提供更大的自发偏振度；(2)具有α-氟-α-甲基手性中心的液晶比具有α-氟-α-CF3手性中心的液晶表现出更大的自发极化，(3)核心部含嘧啶环，手性部分含α-氟-α-甲酯部分的液晶显示出大于400nC/cm~2的自发极化。

The purposes of this project are to develop a new and efficient synthetic method for optically active organofluorine compounds and, by using these as chiral building blocks, to develop new types of ferroelectric liquid crystals.First, the Tokyo Inst.Tech.group has developed the new, silyl triflate-mediated procedure for the Claisen rearrangement and successfully applied this Claisen procedure to asymmetric synthesis of alpha-fluoro-alpha-methyl and alpha-fluoro-alpha-trifluoromethyl carboxylic acid derivatives. Of particular interest is that the senses of asymmetric transmission observed with the fluorinated substrates are opposite to those observed with the non-fluorinated counterparts. Second, the Japan Energy Co.group has prepared a variety of liquid crystals by using the optically active fluorine compounds as the chiral building blocks and evaluated their functional properties as ferroelectric LC's. Notable findings are : (I) the fluorinated liquid crystals provide a larger degree of the spontaneous polarization than the non-fluorinated counterparts in general, (2) Liquid crystal with the alpha-fluoro-alpha-methyl chiral center show a greater spontaneous polarization than the liquid crystals with alpha-fluoro-alpha-CF_3 chiral center, and (3) The liquid crystal with a pyrimidine ring in the core part and alpha-fluoro-alpha-methyl ester moiety in the chiral part is shown to provide a greater than 400 nC/cm^2 of spontaneous polarization.