Coexisting Ferroelectric and Ferroelastic Orders in Rare 3D Homochiral Hybrid Bimetal Halides

Molecular multiferroics that simultaneously possess ferroelectric and ferroelastic orders have sparked growing interest due to their promising uses in shape memory devices, actuators, and sensors. However, it is still a great challenge to effectively explore new molecular multiferroic materials with multiple functionalities. Herein, by introducing homochiral molecules as polar groups, we synthesized a new three-dimensional (3D) bimetal halide multiferroic (R3HP)₂RbBiBr₆ (1; R3HP = R-3-hydroxypyrrolidinium). Crystal 1 adopts a mixed face- and corner-sharing Rb^I/Bi^III-centered 4-connected lon topology with a Schläfli symbol of 6⁶. A distinct symmetry breaking with the 2F1 species leads to the emergence of ferroelasticity and biaxial ferroelectricity. Such a 3D homochiral bimetal halide combined with ferroelectricity and ferroelasticity is unprecedented. Moreover, 1 exhibits fascinating circularly polarized luminescence and semiconducting properties. This finding signifies an important step toward exploring new hybrid molecular multiferroic materials with the coexistence of ferroelectricity and ferroelasticity and inspires their future multifunctional applications.