The ferroelectric nematic phase: on the role of lateral alkyloxy chains
The ferroelectric nematic phase: on the role of lateral alkyloxy chains
复制标题
DOI：
10.1080/02678292.2023.2221651
复制
发表时间：
2023-06-11
期刊：
影响因子：
2.2
通讯作者：
Walker, Rebecca
中科院分区：
文献类型：
--
作者：
Cruickshank, Ewan;Pearson, Abigail;Walker, Rebecca
报道了2-烷氧基-4-甲氧基苯甲酸4-（{[4 ′-硝基-（1，1 ′-联苯基）-4-基]氧}羰基）苯酯的合成和表征：1 O（m-On）PEPEBNO_2系列。这些材料包括一个额外的苯环相比，被广泛研究的铁电性液晶原RM 734，增加液晶转变温度。系列的所有成员都表现出常规的N（N）相和铁电的N（N-F）相; T-NI和T-NFN都随着侧链烷氧基链长度n的增加而减小。这四个环系列的性能进行了比较，与类似的三环横向取代的RM 734的变体;额外的苯环的添加有一个显着更显着的效果比T-NFN的T-NI的值。T-NI的增加可能是由于苯环的插入引起的增强的结构各向异性和更有利的分子间相互作用，而对T-NFN的弱得多的影响可能反映了分子形状的变化。我们还报道了两个三环结构的化合物，4 ′-硝基-（1，1 ′-联苯基）-4-基-2-烷氧基-4-甲氧基苯甲酸酯：1 O（m-On）PEBNO_2（n = 1和2）. RM 734和1 O（m-O 1）PEPNO 2之间的酯键的去除使N-F相消失，这似乎与其中分子被描述为纵向表面电荷密度波的模型一致。
The synthesis and characterisation of the 4-({[4'-nitro-(1,1'-biphenyl)-4-yl]oxy}carbonyl)phenyl 2-alkoxy-4-methoxybenzoates are reported: the 1O(m-On)PEPEBNO2 series. These materials include an additional phenyl ring compared to the extensively studied ferroelectric nematogen RM734, added to increase the liquid crystal transition temperatures. All members of the series exhibited both conventional nematic (N) phase and ferroelectric nematic (N-F) phases; T-NI and T-NFN both decrease on increasing n, the length of the lateral alkoxy chain. The properties of this four-ring series are compared with analogous three-ring laterally substituted variants of RM734; the addition of the extra phenyl ring has a significantly more pronounced effect on the value of T-NI than on T-NFN. The increase in T-NI may be attributed to the enhanced structural anisotropy and more favourable intermolecular interactions arising from the insertion of the phenyl ring, whereas the much weaker effect on T-NFN may reflect a change in the shape of the molecule. We also report two materials with three-ring structures, the 4'-nitro-(1,1'-biphenyl)-4-yl 2-alkoxy-4-methoxybenzoates: 1O(m-On)PEBNO2 (n = 1 and 2). The removal of the ester linkage between RM734 and 1O(m-O1)PEPNO2 extinguishes the N-F phase and this appears to be consistent with a model in which the molecules are described in terms of a longitudinal surface charge density wave.