Thompson Sam Y, Abeyasekere Rebecca H, Page Samuel J, Hodgkinson Paul, Scott Cameron A M, Bristowe Nicholas C, Wagstaff Oliver J, Evans John S O
Department of Chemistry, Durham University, Lower Mount Joy, South Road, Durham DH1 3LE, U.K.
Centre for Materials Physics, Durham University, Durham DH1 3LE, U.K.
Cryst Growth Des. 2025 Jul 21;25(15):6237-6247. doi: 10.1021/acs.cgd.5c00666. eCollection 2025 Aug 6.
Molecular ferroelectrics are an important class of materials offering chemical versatility, low toxicity, and tunable functional properties. A major design challenge lies in achieving multiaxial properties akin to inorganic perovskite ferroelectrics. Here, we report a series of new potential multiaxial molecular ferroelectrics obtained by introducing chiral cations into a structure type known to undergo a phase transition that raises the symmetry significantly. Three of the compounds studied show an Aizu 3̅ phase transition, resulting in 24 equiv polarization directions in the polar phase. H solid-state NMR was used to study the dynamics of the organic cation, confirming rapid rotation about the 3-fold rotation axis of the cubic cell. This blurs the chiral center to an X-ray probe, making the distinction between Sohncke and non-Sohncke space group choices redundant.
分子铁电体是一类重要的材料，具有化学多样性、低毒性和可调节的功能特性。一个主要的设计挑战在于实现类似于无机钙钛矿铁电体的多轴特性。在此，我们报告了一系列新的潜在多轴分子铁电体，它们是通过将手性阳离子引入一种已知会发生相变且对称性显著提高的结构类型中获得的。所研究的三种化合物显示出爱津3̅相变，在极性相中产生24个等效极化方向。利用高分辨固态核磁共振研究了有机阳离子的动力学，证实了其围绕立方晶胞的三重旋转轴快速旋转。这使得手性中心对于X射线探针而言变得模糊不清，从而使 Sohncke 空间群和非 Sohncke 空间群选择之间的区分变得多余。
