Liquid crystalline alkane-3,4-dienoates (allenylacetates) have been
synthesized. Most compounds incorporate a heterocyclic 1,3,4-thiadiazole
ring or a pyrimidine ring as a constituent of the rigid core. These axial
chiral allene derivatives were at first obtained as racemic mixtures. Some
of them were also synthesized in enantiomerically enriched form by
enantioselective synthesis. The compounds were investigated by polarizing
microscopy and by differential scanning calorimetry. The three-ring
compounds exhibit broad regions of smectic C-phases. The optically active
three-ring compounds show broad S
c
*-phases with moderate values
of spontaneous polarization.
液晶
烷烃-3,4-二烯酸盐(烯基
乙酸盐)已被合成。大多数化合物的刚性核心都包含一个杂环 1,3,4-
噻二唑环或一个
嘧啶环。这些轴向手性烯衍
生物最初是以外消旋混合物的形式获得的。其中一些还通过对映体选择性合成获得了对映体富集形式。这些化合物通过偏光显微镜和差示扫描量热法进行了研究。
三环化合物呈现出宽广的胶状 C 相区域。具有光学活性的
三环化合物显示出宽广的 S c * 相,自发极化值适中。