Structural phase transition in a new organic-inorganic hybrid post-perovskite: (N,N-dimethylpyrrolidinium)[Mn(N(CN)2)3]

In the realm of molecular phase transition research, particularly for applications in sensors, data storage, and switching technologies, the role of organic-inorganic hybrid perovskite materials has been increasingly recognized for their significant potential. Nevertheless, hybrid post-perovskites, as a critical subclass of perovskites, has not been thoroughly studied and mainly limits in the instances based on polyatomic bridging agents like dicyanamide (dca−) and non-cyclic organic cations. Herein, a polar cyclic quaternary ammonium cation, N,N-dimethylpyrrolidinium (DMP+), was used to assemble a new hybrid post-perovskite, (DMP)[Mn(dca)3] (1), which undergoes a phase transition from orthorhombic Bmmb to monoclinic P21/n space group at 249 K. By employing multiple techniques such as differential scanning calorimetry, variable-temperature single-crystal X-ray analysis, dielectric measurements, and Hirshfeld surface analysis, we disclosed the role of polar cyclic quaternary ammonium DMP+ in elevating the phase-transition temperature by 48 K, generating significant dielectric switching effect, and facilitating interlayer sliding of inorganic framework.