少しいびつな“王冠型分子”を使って、電気の＋/－と磁石のN/Sをそれぞれ反転できる分子結晶を実現 ―“分子機能の積み木”を組み上げていく新しい多機能材料の設計―

2026-10-07 山口大学

図1．加熱によるクラウンエーテル分子の形と向きの変化、強誘電性、及び分極反転の仕組み

＜関連情報＞

• https://www.yamaguchi-u.ac.jp/weekly/52171/index.html
• https://pubs.acs.org/jacsat/article-abstract/doi/10.1021/jacs.6c10197/5275777/Low-Symmetry-Crown-Ether-Design-for-Coexisting

二次元分子結晶における強誘電性と強磁性の共存を実現するための低対称クラウンエーテル設計 Low-Symmetry Crown Ether Design for Coexisting Ferroelectricity and Ferromagnetism in a Two-Dimensional Molecular Crystal

Jia-bing Wu;Kiyonori Takahashi;Masaru Fujibayashi;Ryo Tsunashima;Yasutaka Suzuki;Jun Kawamata;Masato Haneda;Sadafumi Nishihara;Shin-ichiro Noro;Xin Chen;Ichiro Hisaki;Tomoyuki Akutagawa;Rui-Kang Huang;Takayoshi Nakamura
Journal of the American Chemical Society  Published:August 18, 2026
DOI:https://doi.org/10.1021/jacs.6c10197

Abstract

Multiferroics combining ferroelectricity and ferromagnetism within a single phase are promising materials for magnetoelectric (ME) functionalities. Compared with oxide-based systems, molecular materials offer greater structural tunability for realizing coupled ferroic behavior. Here we report a low-symmetry crown ether design for constructing a layered molecular crystal of [(o-fluoroanilinium⁺)(benzo[18]crown-6)][Mn^IICr^III(oxalate)₃]⁻, in which supramolecular ferroelectricity coexists with two-dimensional ferromagnetic layers. This compound undergoes a reversible, single-crystal-to-single-crystal phase transition driven by the reorientation and conformational change of the polar benzo[18]crown-6 molecule, involving a 180° in-plane rotation and transformation of a polar V-shaped conformation into a planar configuration. Single-crystal X-ray diffraction, dielectric measurements, pyroelectric current, P–E hysteresis loops, and magnetic susceptibility measurements support the coexistence of ferroelectricity and ferromagnetism. Density functional theory (DFT) calculations and structural analysis identify the noncollinear supramolecular geometry of benzo[18]crown-6 units, their tilted assemblies, and the bistable motion as the origin of spontaneous polarization. This work demonstrates the effectiveness of the low-symmetry crown ether in designing molecular multiferroics.