High dielectric permittivity and relaxation-induced dielectric pulsing effect-like in [1,3-bis(1-methylimidazolium)propane][Pb₂I₆] crystal

Herein, a new hybrid, [1,3-bis(1-methylimidazolium)propane][Pb₂I₆] (1), was synthesized and thoroughly characterized using microanalysis, thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and powdered X-ray diffraction (PXRD) techniques. The crystal structure of 1 reveals one-dimensional face-sharing PbI₆ octahedral chains composed of Pb²⁺ and I⁻ ions, with the disordered 1,3-bis(1-methylimidazolium)propane dications positioned between these inorganic chains. Remarkably, 1 exhibits high dielectric permittivity (∼200) across a wide temperature range of 123–423 K. Moreover, it demonstrates a relaxation-induced dielectric pulsing effect-like, characterized by a broad and temperature-independent dielectric anomaly peak around 263 K in ε'−T plots. The mechanisms responsible for the high dielectric permittivity and the origin of the relaxation-induced dielectric pulsing effect-like are further discussed through a comprehensive analysis of the variable-temperature crystal structure.