Supramolecular Bola-Like Ferroelectric: 4-Methoxyanilinium Tetrafluoroborate-18-crown-6

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• 作者：Da-Wei Fu ; Wen Zhang ; Hong-Ling Cai ; Yi Zhang ; Jia-Zhen Ge ; Ren-Gen Xiong ; Songping D. Huang
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：August 17, 2011
• 年：2011
• 卷：133
• 期：32
• 页码：12780-12786
• 全文大小：1038K
• 年卷期：v.133,no.32(August 17, 2011)
• ISSN：1520-5126

文摘

Molecular motion is one of the structural foundations for the development of functional molecular materials such as artificial motors and molecular ferroelectrics. Herein, we show that pendulum-like motion of the terminal group of a molecule causes a ferroelectric phase transition. Complex 4-methoxyanilinium tetrafluoroborate-18-crown-6 ([C₇H₁₀NO(18-crown-6)]⁺[BF₄]^{鈭?/sup>, 1) shows a second-order ferroelectric phase transition at 127 K, together with an abrupt dielectric anomaly, Debye-type relaxation behavior, and the symmetry breaking confirmed by temperature dependence of second harmonic generation effect. The origin of the polarization is due to the order鈥揹isorder transition of the pendulum-like motions of the terminal para-methyl group of the 4-methoxyanilinium guest cation; that is, the freezing of pendulum motion at low temperature forces significant orientational motions of the guest molecules and thus induces the formation of the ferroelectric phase. The supramolecular bola-like ferroelectric is distinct from the precedent ferroelectrics and will open a new avenue for the design of polar functional materials.}