Synthesis and Phase Transition Behaviours of a Homologous Series of Pyridine Symmetrical Dimers
作者:Lay-Khoon Ong、Sie-Tiong Ha、Guan-Yeow Yeap
DOI:10.14233/ajchem.2013.14295
日期:——
A series of symmetrical dimers bearing heterocyclic ring, a,w-bis-(4-pyridine-4-methylideneaminoxy) alkanes, were prepared and all the members are differed by the alkyl spacer length (CnH2n, where n = 6, 8, 10, 12). Differential scanning calorimetry and polarizing optical microscopy techniques were employed to study their transition temperatures and mesophase characteristics. Differential scanning calorimetry thermograms displayed direct isotropization and recrystallization during heating and cooling processes, respectively. The crystal phase texture changed to dark region (isotropic stage) without exhibiting any mesophase. Influence of molecular structure on the mesomorphic properties of symmetrical dimers was also reported.
一系列具有杂环的轴对称二聚体,即α,ω-双-(4-吡啶-4-亚甲氨基氧基)烷烃,被制备出来,所有成员的区别在于烷基间隔长度(CnH2n,其中n = 6, 8, 10, 12)。采用差示扫描量热法和偏光显微镜技术研究了它们的转变温度和介晶特性。差示扫描量热法的温度图显示,在加热和冷却过程中分别出现了直接各向同性和再结晶现象。晶体相的纹理转变为暗区(各向同性阶段),没有显示出任何介晶相。还报道了分子结构对对称二聚体介晶性质的影响。