Controllable Structures Designed with Multiple-Dielectric Responses in Hybrid Perovskite-Type Molecular Crystals.

In this report, two new hybrid organic-inorganic perovskite-type compounds, (IBA)CdBr3 (1; IBA = isobutylammonium cation, i-C4 H9 -NH3 ) and (IBA)2 CdBr4 (2), have been successfully synthesized by reasonable modulation of the ratio of the reactants. 1 with a one-dimensional (1D) chained structure presents sequential solid-state phase transitions, and 2 with a two-dimensional (2D) layered structure undergoes triple structural phase transitions. The phase transitions are attributable to the stepwise ordering process of the organic IBA cation of the title compounds, which also exhibit temperature-dependent dielectric transitions and dielectric anisotropies. Among the different structural environments, the dynamic motions of organic cations show distinct differences, driving the variation of physical properties.