Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications.
Molecular Shape, Electronic Factors, and the Ferroelectric Nematic Phase: Investigating the Impact of Structural Modifications.
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分子形状、电子因素和铁电向列相：研究结构修改的影响。
DOI：
10.1002/chem.202300073
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Tufaha N
中科院分区：
文献类型：
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作者：
Tufaha N
报道了两个系列低摩尔质量液晶原（4-硝基苯基）2-烷氧基-4-（4-甲氧基苯甲酰基）氧基苯甲酸酯（NT3.m）和（3-氟-4-硝基苯基）2-烷氧基-4-（4-甲氧基苯甲酰基）氧基苯甲酸酯（NT3F.m）的合成和表征，以研究改变甲氧基取代的端环侧烷氧基链位置的影响以RM734为基础的这两个系列材料中的中心苯环。 NT3.ms系列的所有成员都表现出传统的向列相N，其先于铁电向列相NF，而NT3F.ms系列的所有成员都表现出直接的NF-I转变，除了NT3F.1也表现出N相。这些材料不能被描述为楔形，但它们的铁电向列-向列转变温度T值超过了侧烷氧基链位于甲氧基取代端环上的相应材料。在某种程度上，这可能归因于改变侧烷氧基链的位置对这些材料的电子性能的影响，特别是对与甲氧基取代的末端芳环相关的电子密度的影响。随着 NT3F.1 中与硝基邻接的氟原子的添加，TNI 值降低，然而，当比较 NF 相的转变温度时发现了相反的行为，NT3F.m 系列的转变温度较高。这可能反映了 NT3F.mseries 与 NT3.mseries 相比极性和极化率的变化。因此，有人认为，侧链在抑制反平行缔合中的作用及其对分子电子性质的影响是驱动NF相形成的关键因素，而不是简单地促进锥形形状。
The synthesis and characterisation of two series of low molar mass mesogens, the (4‐nitrophenyl) 2‐alkoxy‐4‐(4‐methoxybenzoyl)oxybenzoates (NT3.m) and the (3‐fluoro‐4‐nitrophenyl) 2‐alkoxy‐4‐(4‐methoxybenzoyl)oxybenzoates (NT3F.m), are reported in order to investigate the effect of changing the position of a lateral alkoxy chain from the methoxy‐substituted terminal ring to the central phenyl ring in these two series of materials based on RM734. All members of the NT3.mseries exhibited a conventional nematic phase, N, which preceded the ferroelectric nematic phase, NF, whereas all the members of the NT3F.mseries exhibited direct NF‐I transitions except for NT3F.1 which also exhibited an N phase. These materials cannot be described as wedge‐shaped, yet their values of the ferroelectric nematic‐nematic transition temperature,T, exceed those of the corresponding materials with the lateral alkoxy chain located on the methoxy‐substituted terminal ring. In part, this may be attributed to the effect that changing the position of the lateral alkoxy chain has on the electronic properties of these materials, specifically on the electron density associated with the methoxy‐substituted terminal aromatic ring. The value ofTNIdecreased with the addition of a fluorine atomorthoto the nitro group in NT3F.1, however, the opposite behaviour was found when the transition temperatures of the NFphase were compared which are higher for the NT3F.mseries. This may reflect a change in the polarity and polarizability of the NT3F.mseries compared to the NT3.mseries. Therefore, it is suggested that, rather than simply promoting a tapered shape, the role of the lateral chain in inhibiting anti‐parallel associations and its effect on the electronic properties of the molecules are the key factors in driving the formation of the NFphase.