Organosilicon cluster goes ferroelectric

Ferroelectrics and clusters have independently attracted significant attention as two important classes of functional materials. Bridging these two fields by introducing ferroelectricity into clusters offers a compelling strategy to overcome the intrinsic limitations of conventional small-molecule materials. However, cluster-based ferroelectrics remain exceedingly rare and challenging to realize. In this study, we report the construction of an organosilicon molecular cluster ferroelectric, aminopropyl isobutyl Si₈O₁₂ cluster (1), achieved by introducing distorted tetrahedral units with a polar -NH₂ group. Crystal 1 undergoes a 3F1-type ferroelectric-ferroelastic phase transition at 328 K, accompanied by a distinct on/off switching behavior of optical birefringence. Comprehensive structural and physical characterizations confirm the coexistence of ferroelectricity and ferroelasticity. Remarkably, this multiferroic crystal demonstrates excellent thermal stability, high chemical robustness, a large number of polar axes, pronounced entropy change, and a low elastic modulus compared with previously reported organosilicon ferroelectric crystals. To the best of our knowledge, Crystal 1 is the first organosilicon cluster ferroelectric, establishing a new design paradigm for organosilicon and molecular ferroelectrics.