Observation of Transition from Ferroelasticity to Ferroelectricity by Solvent Selective Effect in Anilinium Bromide

Abstract

Organic ferroelectrics are highly desirable for their light weight, mechanical flexibility and biocompatibility. However,t he rational design of organic ferroelectrics has always faced great challenges.A nilinium bromide (AB) has two structures reported in the Cambridge Crystallographic Data Centre,w hich might be an mmmF2/m type ferroelastic (AB-1). When we studied its ferroelasticity,wewere surprised to discover that there was another crystal (AB-2) in H 2 O besides this one,a nd they were very difficult to separate.B y changing the solvent, we found that AB-1 crystals could be formed in ethanol, where ferroelastic domains were visualized by polarized light microscopy, and AB-2 crystals could be obtained from various crystallization solvents of methanol, isopropanol, N-butanol, acetonitrile,d imethyl sulfoxide,a nd N,N-dimethylformamide,w hich undergo af erroelectric phase transition with mm2Fm, showing clear ferroelectricity in two phases.T oo ur knowledge,t he regulation of ferroelasticity to ferroelectricity by solvent selective effect is unprecedented in the field of ferroelectrics.This work reveals the important role of solvent effect in organic ferroelectrics.

A ferroelastic molecular rotator [(Me2N(CH2)2NH3)(18-crown-6)]triflate with dual dielectric switches

“…These reasons undoubtedly promote the exploration of ferroelastics from inorganic materials to organic molecules. [18][19][20][21][22][23][24] In particular, as a representative of organic molecules, the crown ether-based molecular rotators show a special structure: the crown ether as a stator to fix the rotator cation through hydrogen bonds, and the counterion. [25][26][27][28][29][30] This structure is considered as a promising template for the construction ferroelastic phase transition and switchable materials, because it facilitates the dynamic motions of building blocks.…”