The First High‐Temperature Supramolecular Radical Ferroics

Abstract

Organic radical ferroics such as TEMPO have attracted widespread interest. However,the relatively low Curie temperature of 287 Ka nd melting point of 311 Ks everely hinder its application potential. Despite extensive interest, high-temperature radical ferroics have not yet been found. Here,taking advantage of chemical design and supramolecular radical chemistry,w ed esigned two high-temperature organic supramolecular radical ferroics [(NH 3 -TEMPO)([18]crown-6)](ReO 4 )( 1)and [(NH 3 -TEMPO)([18]crown-6)](ClO 4 )(2), which can retain ferroelectricity up to 413 Ka nd 450 K, respectively.T oo ur knowledge,t hey are both the first supramolecular radical ferroics and unprecedented hightemperature radical ferroics,w here the supramolecular component is vital for the stabilization of the radical and extending the working temperature window. Both also have paramagnetism, non-interacting spin moments,a nd excellent piezoelectric and electrostrictive behaviors comparable to that of LiNbO 3 .

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

“…[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. 27,[31][32][33][34][35][36] So far, crown ether-based ferroelastic molecular rotators are rarely reported.…”

Unusual high-temperature host–guest inclusion compound-based ferroelectrics with nonlinear optical switching and large spontaneous polarization behaviours

“…In the past ten years, some new crown ether-based inclusion compounds (Table S3, ESI †) have been successfully synthesized on the basis of this theory, but there is still a lot of room for structural modification: (i) the phase transition temperature of most crown ether-based inclusion compounds is usually lower than room temperature; (ii) most crown etherbased inclusion compounds crystallize in the centrosymmetric space group, resulting in a few NLO switching materials for application; (iii) usually they have small spontaneous polarization and uniaxial characteristics, the above shortcomings seriously hinder their practical application, such as [ (2,6- 12 [(4-methoxyanilinium)(18-crown-6)][BF 4 ](T c = 127 K), 13 ] and [(NH 3 -TEMPO)(18-crown-6)](ClO 4 ). 15 It provides ideas for the design of high temperature multiaxial ferroelectrics. For a material to become a ferroelectric, it must meet the basic conditions, such as undergoing a reversible structural phase change, and the ferroelectric phase must crystallize into 10 polar point groups (C 1 , C 2 , C s , C 2v , C 4 , C 4v , C 3 , C 3v , C 6 and C 6v ).…”

“…successfully designed three kinds of multiaxial high temperature ferroelectrics according to the idea of chemical design, [(MeO-C 6 H 4 -NH 3 )-(18-crown-6)][TFSA], 14 [(NH 3 -TEMPO)([18-crown-6)](ReO 4 )] and [(NH 3 -TEMPO)(18-crown-6)](ClO 4 ). 15 It provides ideas for the design of high temperature multiaxial ferroelectrics. For a material to become a ferroelectric, it must meet the basic conditions, such as undergoing a reversible structural phase change, and the ferroelectric phase must crystallize into 10 polar point groups ( C 1 , C 2 , C s , C 2v , C 4 , C 4v , C 3 , C 3v , C 6 and C 6v ).…”