Nopinic acid is an unprece dente d homochiral single-component organic ferroelectric
Nopinic acid is an unprece dente d homochiral single-component organic ferroelectric
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Nopinic Acid 是一种前所未有的齿状同手性单组分有机铁电体
DOI：
10.1016/j.apmt.2020.100687
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发表时间：
2020
影响因子：
8.3
通讯作者：
Tang Yun-Zhi
中科院分区：
文献类型：
--
作者：
Yang Kang;Dong Xing-Xian;Xu Qing;Tan Yu-Hui;Tang Yun-Zhi
自1921年Valasek发现第一个纯手性铁电晶体罗谢尔盐（NaKC_4 H_4 O_6·4 H_2 O）以来，尽管在过去的十年中发现了许多单组分纯手性有机分子铁电体，但迄今为止，单组分纯手性有机分子铁电体仍处于空白状态。在这里，我们提出了第一个例子的纯手性单组分有机铁电体，诺频酸，（2-羟基-6，6-二甲基双环[3，1，1]庚烷-2-羧酸），1，它经历了一个独特的铁电体到铁电体相变约161 K从空间群C2到P1。热反常、介电常数的可切换性以及随温度变化的倍频响应直接证实了其可逆相变行为。进一步的X射线单晶衍射分析表明，随着温度的变化，H-质子的相对位移运动引起双螺旋诺频酸链的集体沿着方向移动，导致可逆相变。利用压电响应力显微镜（PFM）对1薄膜的测量，在纳米尺度上探测和转换了薄膜的局部铁电极化，直接证明了其铁电性。由于其固有的手性，灵活性，环境友好，易于加工的能力，和室温极化开关，我们相信这些发现提供了一个新的途径，探索高性能铁电体。
Since the first homochiral ferroelectric crystal Rochelle salt (NaKC4H4O6•4H2O) was discovered in 1921 by Valasek, the single-component homochiral organic molecular ferroelectrics still remain unexplored although a number of molecular ferroelectrics were discovered in the past decade. Here we present the first example of homochiral single component organic ferroelectric, nopinic acid, (2-hydroxy-6, 6-dimethyl bicycle [3, 1, 1] heptane-2-carboxylic acid), 1, which experiences a unique ferroelectric to ferroelectric phase transition around 161 K from space groupC2 toP1. The heat anomaly, switchable dielectric and varied SHG responses dependence on temperatures directly confirm its reversible phase transition behavior. The further X-ray single crystal diffraction analysis indicates that with the temperature changes the relative displacement motions of H-proton caused the collective shift along the direction of double helical nopinic acid chains, and results the reversible phase transition. The piezo-response force microscopy (PFM) measurements on thin films of1probed and switched the local ferroelectric polarization at the nanoscale, and directly proved its ferroelectricity. Because of its inherent chirality, flexibility, environment-friendly, easy process ability, and room-temperature polarization switching, we believe these finding affords a new venue to explore for high performance ferroelectrics.