Homochiral anionic modification toward the chemical design of organic enantiomeric ferroelectrics

Modulating the ferroelectric phases in cholesteryl-based organic compounds with perfluoroalkyl tail engineering

Here, we synthesized a series of cholesteryl-based compounds, whose phases and their transformation can be modulated by temperature and the chain length of the fluoroalkyl moieties. To our knowledge, this is the first time that the phase transition could be modulated with perfluoroalkyl tail engineering in organic single-component ferroelectric crystals.

Zero-Dimensional Sn-Based Enantiomeric Phase-Transition Materials with High-Tc and Dielectric Switching

The combination of chirality and phase-transition materials has broad application prospects. Therefore, based on the quasi-spherical theory and the thought strategy of introducing chirality, we have successfully synthesized a pair of chiral enantiomeric ligands (R/S)-triethyl-(2-hydroxypropyl)ammonium iodide, which can be combined with a tin hexachloride anion to obtain a pair of new organic-inorganic hybrid enantiomeric high-temperature plastic phase-transition materials: (R/S)-[CH3 CH(OH)CH2 N(CH2 CH3 )3 ]2 SnCl6 (1-R/1-S), which have a high temperature phase transition of Tc =384 K, crystallize in the P21 chiral space group at room temperature, and have obvious CD signals. In addition, compounds 1-R and 1-S have a good low-loss dielectric switch and broadband gap. This work is conducive to the research into chiral high-temperature reversible plastic phase-transition materials, and promotes the development of multi-functional phase-transition materials.

2-Chloroethylamine·trifluoromethanesulfonate combined with 18-crown-6: a ferroelectric with excellent dielectric switching properties

Ferroelectric materials are not only important electronic functional materials, but also considered as the most promising intelligent basic materials, because they show good application prospects. Therefore, it is an urgent task to develop and explore new ferroelectric material systems. In addition, the most important feature of crown ethers is their ability to complex with positive ions, which is extremely useful in synthesis. We report that [NH3C2H4Cl(18-crown-6)](CF3SO3) (1) has a phase transition temperature Tc = 255 K, and there is an obvious SHG switch below Tc. At the same time, the saturation polarization value Ps = 1.25 μC cm-2 is obtained from the hysteresis loop, which directly proves the ferroelectric nature of compound 1. It is noteworthy that the second harmonic response test of compound 1 shows a symmetric transition from a non-centrosymmetric to a centrosymmetric point group, that is a symmetry break from the paraelectric phase to the ferroelectric phase. This work is expected to promote the further exploration of organic crown ether ferroelectrics and provide a way to design and synthesize organic crown ether ferroelectrics.

Two quasi-spherical molecules [1,4-diazabicyclo(3.2.2)nonane]X (X = ClO4, ReO4) exhibit switchable phase transition, dielectric and second-harmonic-generation properties

Two quasi-spherical molecules [3.2.2-Hdabc]X (1,4-diazabicyclo[3.2.2]nonane = 3.2.2-dabcn, X = ClO4, ReO4) with a high phase transition temperature exhibited switchable phase transition as well as dielectric and SHG properties.

High temperature molecular-based phase transition compounds with tunable and switchable dielectric properties

Molecular-based dielectric switching compounds [ClEt-Dabco][ReO4]2 and [BrEt-Dabco][ReO4]2 with high-temperature phase transition.