The influence of molecular shape and electronic properties on the formation of the ferroelectric nematic phase
The influence of molecular shape and electronic properties on the formation of the ferroelectric nematic phase
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DOI：
10.1080/02678292.2024.2304598
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发表时间：
2024-01
期刊：
影响因子：
2.2
通讯作者：
E. Cruickshank;Naila Tufaha;R. Walker;Stevie Brown;E. Górecka;D. Pociecha;J. Storey;C. Imrie
中科院分区：
文献类型：
--
作者：
E. Cruickshank;Naila Tufaha;R. Walker;Stevie Brown;E. Górecka;D. Pociecha;J. Storey;C. Imrie
本文报道了两个系列的基于RM 734的铁电致变色剂的合成和表征，它们分别是3-甲氧基-4-（（4-硝基苯氧基）羰基）苯基2-烷氧基-4-烷氧基苯甲酸酯（7-m-n）和3-甲氧基-4-（（3-氟-4-硝基苯氧基）羰基）苯基2-烷氧基-4-烷氧基苯甲酸酯（8-m-n）。为了将这些系列的行为与在中心苯环上不含甲氧基的相应材料的行为进行比较，我们还报道了4-[4-（2-甲氧基苯基）-2-甲基]-2-甲基-苯并[4-（2-甲氧基苯基）-2-甲基]-2-甲基-苯并[4（4-硝基苯氧基）羰基]苯基4-甲氧基苯甲酸酯（11-0-1），4-[（3-氟-4-硝基苯氧基）羰基]苯基4-甲氧基苯甲酸酯（12-0-1）和4-[（3-氟-4-硝基苯氧基）羰基]苯基2，4-二乙氧基苯甲酸酯（12-2-2）。还描述了其中侧乙氧基链连接到中心环的两种化合物，3-乙氧基-4-[（4-硝基苯氧基）羰基]苯基2，4-二甲氧基苯甲酸酯（18-2-1）和3-乙氧基-4-[（3-氟-4-硝基苯氧基）羰基]苯基2，4-二甲氧基苯甲酸酯（19-2-1）。这些材料的行为表明，相对稳定的铁电体的N，NF，和传统的N，N相的空间和电子因素的微妙的相互作用。此外，电子因素更好地理解在电子密度的孤立区域，而不是由一个单一的大纵向偶极矩。在分子形状方面，为了观察NF相，似乎分子结构必须包括一个或多个横向取代基，其增强分子双轴性并使N相不稳定。图形摘要
ABSTRACT The synthesis and characterisation of two series of ferroelectric nematogens based on RM734 having an additional methoxy group on the central phenyl ring are reported, the 3-methoxy-4-((4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (7-m-n) and the 3-methoxy-4-((3-fluoro-4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (8-m-n). In order to compare the behaviour of these series to those of the corresponding materials that do not contain the methoxy group on the central phenyl ring, we also report the synthesis and characterisation of 4-[(4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (11-0-1), 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (12-0-1) and 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-diethoxybenzoate (12-2-2). Two compounds in which a lateral ethoxy chain is attached to the central ring, 3-ethoxy-4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (18-2-1) and 3-ethoxy-4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (19-2-1), are also described. The behaviour of these materials shows that the relative stabilities of the ferroelectric nematic, NF, and conventional nematic, N, phases are governed by a subtle interplay of steric and electronic factors. Furthermore, the electronic factors are better understood in terms of isolated regions of electron density rather than by a single large longitudinal dipole moment. In terms of molecular shape, to observe the NF phase it appears that the molecular structure must include one or more lateral substituents that enhance molecular biaxiality and destabilise the N phase. GRAPHICAL ABSTRACT