Bromination of organic spacer impacts on the structural arrangement, phase transitions, and optical and electrical properties of a hybrid halide compound:[(CH3)3N(CH2)3Br]2PdBr4

Abstract

Understanding the structure and arrangement of organic inorganic hybrid metal halides and their contribution to physical properties remains a challenging topic. In particular, materials involving d⁸ metal halides incorporating organo-halogen components are still largely unexplored. In this study, we have used precise reagents to design and synthesize a low dimensional semiconductor material, [(CH₃)₃N(CH₂)₃Br]₂PdBr₄. Crystals were prepared through slow evaporation. Through the reactions of (3-bromopropyl)trimethylammonium bromide with PdBr₂ in an aqueous HBr solution, we successfully obtained a 0D organic–inorganic hybrid material, [(CH₃)₃N(CH₂)₃Br]₂PdBr₄. This compound exhibits two reversible phase transitions, at 363 K and 393 K, assigned to an order/disorder change and a rare congruent melting. These transitions are confirmed through DSC analysis, temperature dependent Raman studies and electrical measurements. The crystals remained stable up to 520 K. Furthermore, we measured the UV-visible absorption spectrum of the polycrystalline sample to estimate the band gap, which was found to be approximately 2 eV. The halogen atom in the organic spacer has a considerable impact on the structure, high-temperature phase transition, and semiconducting characteristics, as revealed in this work.