Mesomorphism and flexibility of alkyl chains in chalcone esters
Mesomorphism and flexibility of alkyl chains in chalcone esters
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DOI：
10.1080/15421406.2016.1221989
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发表时间：
2016-10
影响因子：
0.7
通讯作者：
N. R. Muniya;V. Patel
中科院分区：
文献类型：
--
作者：
N. R. Muniya;V. Patel
摘要合成并研究了一种新的同系查尔酮酯液晶：RO− C6 H4-CH：CH-COO− C6 H4-CO−CH：CH− C6 H4-OC 10 H21（n）（帕拉），旨在了解和建立分子结构与液晶性能之间的关系，并参考末端链的柔性。新系列由11个同系物（C1-C16）组成。C_1和C_2同系物为非液晶，其余同系物（C_3-C_16）为各向异性液晶，无近晶相。通过配备有加热台的光学偏振显微镜测定转变和熔融温度。第二相的纹理是螺纹或纹影。Cr-N/I过渡曲线呈锯齿形，总体呈下降趋势。从C_3到C_6，N-I转变曲线表现出尖锐的、较短的奇偶效应，并且对于较长正烷基链（R）的高级同系物，从C_6开始和超过C_6，N-I转变曲线以或多或少或可忽略不计的偏离正常下降趋势的方式减小。C3和C12同系物的热稳定性分别为116.4°C和中间相长度为19°C至67°C。将本新系列的LC性质与结构相似的类似系列进行比较，得出群效率阶。
ABSTRACT A novel homologous series of chalconyl ester liquid crystals (LCs): RO−C6H4–CH:CH–COO−C6H4–CO−CH:CH−C6H4–OC10H21 (n) (para) has been synthesized and studied with a view to understanding and establishing the relationship between molecular structure and LC properties with reference to flexibility of the terminal chain. The novel series consists of eleven homologs (C1–C16). The C1 and C2 homologs are nonliquid crystals and the rest of the homologs (C3–C16) are enantiotropic nematic without exhibition of smectic mesophase. Transition and melting temperatures were determined by an optical polarizing microscope equipped with a heating stage. Textures of nematic phases are threaded or Schlieren. Cr-N/I transition curve adopts a zigzag path in a normal manner with overall descending behaviors. The N-I transition curve exhibits a sharp and shorter odd-even effect from C3 to C6 and it diminishes from and beyond C6 for higher homologs of longer n-alkyl chain (R) in more or less or negligible deviating manner from normal descending tendency. Thermal stability for the nematic is 116.4°C and mesophase length ranges from 19°C to 67°C at the C3 and C12 homolog respectively. The LC properties of present novel series are compared with structurally similar analogous series to derive group efficiency order.