Mesophase Stabilization in Ionic Liquid Crystals through Pairing Equally Shaped Mesogenic Cations and Anions
作者:Kathrin Stappert、Gregor Lipinski、Gabriel Kopiec、Eike T. Spielberg、Anja-Verena Mudring
DOI:10.1021/acs.cgd.5b01023
日期:2015.11.4
The synthesis and properties of a set of novel ionic liquid crystals with congruently shaped cations and anions are reported to check whether pairing mesogenic cations with mesogenic anions leads to a stabilization of a liquid crystalline phase. To that avail 1-alkyl-3-methyl-triazolium cations with an alkyl chain length of 10, 12, and 14 carbon atoms have been combined with p-alkyloxy-benzenesulfonate anions with different alkyl chain lengths (n = 10, 12, and 14). The corresponding triazolium iodides have been synthesized as reference compounds where the cation and anion have strong size and shape mismatch. The mesomorphic behavior of all compounds is studied by differential scanning calorimetry and polarizing optical microscopy. All compounds except 1-methyl-3-decyltriazolium iodide, which qualifies as an ionic liquid, are thermotropic ionic liquid crystals. All other compounds adopt smectic A phases. A comparison of the thermal phase behavior of the 1-methyl-3-decyltriazolium bromides to the corresponding p-alkoxy-benzensulfonates reveals that definitely the mesophase is stabilized by pairing the rod-shaped 1-alkyl-3-methyltriazolium cation with a rod-like anion of similar size.
报告了一组具有形状一致的阳离子和阴离子的新型离子液晶的合成和性质,以检验介原阳离子与介原阴离子配对是否会导致液晶相的稳定。为此,我们将烷基链长为 10、12 和 14 个碳原子的 1-烷基-3-甲基三唑阳离子与不同烷基链长(n = 10、12 和 14)的对烷氧基苯磺酸阴离子结合在一起。相应的三唑鎓碘化物是作为阳离子和阴离子具有强烈尺寸和形状不匹配的参考化合物合成的。所有化合物的介形行为都是通过差示扫描量热法和偏振光学显微镜进行研究的。除了 1-甲基-3-癸基三唑碘化物(符合离子液体的条件)外,所有化合物都是热致性离子液晶。所有其他化合物都是熔融 A 相。将 1-甲基-3-癸基三唑溴化物的热相行为与相应的对烷氧基苯磺酸盐进行比较后发现,棒状的 1-烷基-3-甲基三唑鎓阳离子与类似大小的棒状阴离子配对后,介相肯定会得到稳定。