Dielectric switching from a high temperature plastic phase transition in two organic salts with chiral features. Issue 3 (5th January 2022) - Ying, Tingting
Abstract : Two organic ionic crystals were successfully synthesized, namely [N(CH2 CH3 )3 (CH2 Cl)][ClO4 ] (1 ) and [N(CH2 CH3 )3 (CH2 Cl)][BF4 ] (2 ), with high-temperature reversible phase transitions. In addition, compounds 1 and 2 also show obvious CD signals. Abstract : Organic ionic plastic crystals (OIPCs) with high-temperature reversible dielectric switching properties, single chiral characteristics, and the potential for various structural phase transformations provide more possibilities for obtaining different functional properties. Here, we successfully synthesized two organic ionic plastic crystals, namely [N(CH2 CH3 )3 (CH2 Cl)][ClO4 ] (1 ) and [N(CH2 CH3 )3 (CH2 Cl)][BF4 ] (2 ), which have two continuous reversible transitions triggered by the order and disorder of anions and ammonium ions. Interestingly, the dielectric constant of 2 is significantly higher than that of 1 under the same conditions. Impedance testing suggests that the arc radius of 2 is smaller than that of 1, indicating that 2 has a faster photogenerated charge carrier rate and greater conductivity. In addition, adopting the chiral space group P 32 21, 1 and 2 showed obvious CD signals. These two chiral compounds with high-temperature dielectric switching provide new ideas for the design of new phase transition compounds and for the exploration of ionic-crystal-based multifunctional organic materials.