Inversion of Molecular Chirality Associated with Ferroelectric Switching in a High-Temperature Two-Dimensional Perovskite Ferroelectric

Abstract

Controlling molecular chirality by external stimuli is of great significance in both fundamental research and technological applications. Herein, we report a high-temperature (384 K) molecular ferroelectric of a Cu(II) complex whose spontaneous polarization can be switched associated with flipping of molecular chirality. In this two-dimensional perovskite structure, the inorganic layer is separated by (NH₃(CH₂)₂SS(CH₂)₂NH₃)²⁺ organic cations skewed in a chiral conformation (<i>P</i>- or <i>M</i>-helicity in an individual crystal). As the stereodynamic disulfide bridge determines the molecular dipole moment along the polar axis, the chiral organic cation can be converted to its enantiomer as a consequence of an electric field-induced shift of the S-S moiety relative to its screw axis during the ferroelectric switching. The variation of the molecular chirality is examined with single-crystal X-ray diffraction and circular dichroism spectra. The simultaneous switching of molecular chirality and spontaneous polarization in this perovskite ferroelectric may lead to novel chiral electronic phenomena.