Tuning mesomorphic properties and handedness of chiral calamitic liquid crystals by minimal modification of the effective core.
Tuning mesomorphic properties and handedness of chiral calamitic liquid crystals by minimal modification of the effective core.
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DOI：
10.1002/chir.21002
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发表时间：
2011
期刊：
影响因子：
2
通讯作者：
Anhua Liu;Qiming Sun;Jiaxi Cui;Jia Zheng;Wenjian Liu;X. Wan
中科院分区：
文献类型：
--
作者：
Anhua Liu;Qiming Sun;Jiaxi Cui;Jia Zheng;Wenjian Liu;X. Wan
设计合成了(+)-2-[4'-(S)-叔丁基苯基]-5-（4'-己氧苯基）甲苯（(+)-S-1）和(+)-2-（4'-己氧苯基）-5-[4'-(S)-叔丁基苯基]甲苯（(+)-S-2）、(-)-2-[4'-(R)-叔丁基苯基]-5-（4'-己氧苯基）甲苯（(-)-R-1）和(-)-2-（4'-己氧苯基）-5-[4'-己氧苯基]甲苯（(-)-R-2）。每个分子由中间环上被甲基取代的对terphenyl核、手性仲丁基尾和非手性正己基尾组成。（+）- s -1 （(-)- r -1）和(+)- s -2 （(-)- r -2）的几何差异仅在于甲基在有效介生核上的位置。然而，这种结构上的微小变化会引起介生性质和手性的显著差异。（+）- s -1和(-)- r -1均具有对映性胆甾相（N*）和单向扭转晶界C*相（TGBC*），而(+)- s -2和(-)- r -2仅具有单向性N*相。此外，(+)- s -1 （(-)- r -1）和(+)- s -2 （(-)- r -2）在N*相中具有相反的手性，(+)- s -1和(-)- r -1甚至通过非螺旋手性中间相从N*向TGBC*发生螺旋反转。
Two pairs of calamitic liquid crystalline molecules, (+)-2-[4'-(S)-sec-butoxyphenyl]-5-(4'-hexoxyphenyl)toluene ((+)-S-1) and (+)-2-(4'-hexoxyphenyl)-5-[4'-(S)-sec-butoxyphenyl]toluene ((+)-S-2), (-)-2-[4'-(R)-sec-butoxyphenyl]-5-(4'-hexoxyphenyl)toluene ((-)-R-1) and (-)-2-(4'-hexoxyphenyl)-5-[4'-(R)-sec-butoxyphenyl]toluene ((-)-R-2), have been designed and synthesized. Each of the molecules consists of a p-terphenyl core substituted with a methyl group on the middle ring, a chiral sec-butoxy tail, and an achiral n-hexoxy tail. The geometrical difference between (+)-S-1 ((-)-R-1) and (+)-S-2 ((-)-R-2) lies only in the location of the methyl group on the effective mesogenic core. Yet, such a small change in the structure gives rise to remarkable differences in mesogenic properties and handedness. Both (+)-S-1 and (-)-R-1 have an enantiotropic cholesteric phase (N*) and a monotropic twist grain boundary C* phase (TGBC*), whereas (+)-S-2 and (-)-R-2 exhibit only a monotropic N* phase. Moreover, (+)-S-1 ((-)-R-1) and (+)-S-2 ((-)-R-2) have opposite handedness in the N* phase, and (+)-S-1 and (-)-R-1 even have a helical inversion from N* to TGBC* phase through a non-helical chiral mesophase.