Anions Distorting Triggering Ferroelectricity in a Molecular Crystal†.

Comprehensive Summary: Recently, molecular ferroelectrics have attracted more and more attention due to their structural diversity, low cost of manufacture, and environmental‐friendly processing. However, most of the design strategies for molecular ferroelectrics have focused on the selection and modification of cations, and the use of anions has been rarely reported. Here, introducing distorted [CuBr4]2– tetrahedra, we obtained a high curie temperature (Tc) ferroelectric, [cyclopentylammonium]2CuBr4, with a Tc as high as 393 K, and exceeding commercial and most of reported molecular ferroelectric BaTiO3 (393 K). Variable‐temperature hysteresis loop shows the nonlinear P‐E loop of the crystal under a wide temperature range. Variable‐temperature single‐crystal X‐ray diffraction revealed that the Aizu expression can be written as mmmFmm2. In short, this work will inspire more creative strategies by exploiting the tunability of the anion module. [ABSTRACT FROM AUTHOR]