Homochiral Multiferroic Cyanido‐Bridged Dimetallic Complexes Assembled by C−F⋅⋅⋅K Interactions

Abstract

AbstractCyanido‐bridged dimetallic complexes are attracting attention due to their varied structures and properties. However, homochiral cyanido‐bridged dimetallic complexes are rare, and making them ferroelectric is a great challenge. Introducing C−F⋅⋅⋅K interactions between the guest chiral cations and the host [KFe(CN)6]2− framework, gives three‐dimensional cyanido‐bridged dimetallic multiferroics, [R‐ and S‐3‐fluoropyrrolidinium]2[KFe(CN)6] (R‐ and S‐3‐FPC). The mirror‐symmetric vibrational circular dichroism (VCD) signal shows their enantiomeric nature. R‐ and S‐3‐FPC crystallize in the same chiral‐polar space group P21 at 298 K. Piezoresponse force microscopy (PFM), polarizing optical microscopy, and temperature‐dependent second‐harmonic generation (SHG) measurements show their multiferroic properties (the coexistence of ferroelectricity and ferroelasticity), in line with the Aizu notation of 222F2. R‐3‐FPC shows excellent ferroelectricity with saturated polarization up to 9.4 μC cm−2.