Ferroelectricity of Hydrogen-Bonded Azobenzene Derivatives
Ferroelectricity of Hydrogen-Bonded Azobenzene Derivatives
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DOI：
10.1021/acsaelm.1c00462
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发表时间：
2021-08
影响因子：
4.7
通讯作者：
Jianyun Wu;Qingyang Zhu;Takashi Takeda;Norihisa Hoshino;T. Akutagawa
中科院分区：
文献类型：
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作者：
Jianyun Wu;Qingyang Zhu;Takashi Takeda;Norihisa Hoshino;T. Akutagawa
设计了含− CONHC 10 H21链的氢键偶氮苯衍生物（1a，2和3a），并对其铁电响应进行了分析.其中1a和2具有一个氢键烷基酰胺链，而3a在4，4 ′-位具有两个烷基酰胺链.为了提高2分子组装的灵活性，一个癸基（− C10 H21）链被进一步取代成2。在1a和2中发生了固-固相变（S1-S2），而在3a中观察到了层状液晶M1和M2相。对带有− CONHC 4 H9的短链衍生物1band 3b进行了单晶X射线结构分析，以阐明1a，2和3a的氢键和堆积结构。所有化合物均形成了由偶氮苯π-核和烷基链组成的层状结构，烷基链之间通过一维N-H···O-氢键单元连接形成3a的M1或M2相。热激活运动自由度的大小顺序为：1a（S2相）>2（S2相）>3a（M1相）>3a（M2相）。其中，铁电极化-电场磁滞回线被观察到的S2相的2以及M1和M2相的3a，其中的极性氢键链的动态反转被激活，通过施加外电场。此外，3a形成有机凝胶，这是应用于调整的反式和顺式异构体的3a在云母表面的表面形态。
Hydrogen-bonded azobenzene derivatives (1a,2, and3a) bearing a −CONHC10H21chain were designed, and their ferroelectric responses were analyzed.1aand2had one hydrogen-bonded alkylamide chain, whereas3ahad two alkylamide chains at 4,4′-positions. To improve the flexibility of the molecular assembly of2, one decyl (−C10H21) chain was further substituted into2. Solid–solid phase transitions (S1–S2) were induced in1aand2, whereas lamellar-type liquid crystalline M1 and M2 phases were observed in3a. Single-crystal X-ray structural analyses of short-chain derivatives1band3bbearing −CONHC4H9were performed to clarify the hydrogen-bonding and packing structures of1a,2, and3a. All compounds formed a layered structure comprising azobenzene π-core and alkyl chains, which were connected by one-dimensional N–H···O═ hydrogen-bonding units to form the M1 or M2 phase of3a. The magnitude of thermally activated motional freedom decreased in the following order:1a(S2 phase) >2(S2 phase) >3a(M1 phase) >3a(M2 phase). Among them, ferroelectric polarization–electric field hysteresis loops were observed for the S2 phase of2as well as M1 and M2 phases of3a, where the dynamic inversion of the polar hydrogen-bonded chains was activated by applying an outer electric field. Additionally,3aformed an organogel, which was applied to adjust the surface morphologies of the trans- and cis-isomers of3aon the mica surface.