Reversible On/Off Switching of Ferroelectricity in a Molecular FeCo Prussian Blue Analogue with Multiple Control

Abstract

Abstract Polar molecule-based magnetic materials capable of multistate switching have garnered significant interest for their potential applications in next-generation memory devices, sensors, and energy conversion. Among such materials, Prussian blue analogs that exhibit electron transfer–coupled spin transition (ETCST) behavior stand out due to their unique switching properties. In this study, we report a trinuclear cyanide-bridged FeCo compound ( 1 ) that exhibits photo- and thermo-induced ferroelectric phase transition via ETCST mechanism. Notably, this FeCo complex also demonstrates a quenching effect, whereby a non-polar state is trapped as a metastable state at low temperature, allowing the polarization control via the cooling rate variations. In addition, reversible single-crystal-to-single-crystal transformation via the desorption and absorption of solvent molecules are observed. The EtOH-removed FeCo compound ( 1’ ) loses its ferroelectricity, revealing that the ferroelectric phase transition can be modulated by dynamic desorption/adsorption of the guest molecule. These findings advance the design of functional ferroelectric materials with multistate switching capabilities, offering potential for future applications in contactless memory devices and beyond.