H/Br substitution in ethylamine improves the phase transition temperature of in-based material (BrC2H4NH3)3[InBr6

Abstract

Organic-inorganic hybrid phase transition materials with simple synthesis and flexible structure have become a research hotspot. However, one of the obstacles for expanding their application prospects is how to effectively adjust the phase transition temperature. Herein, taking advantage of H/Br substitution on the reported In-based phase transition material (C2H5NH3)3[InBr6], a new In-based material (BrC2H4NH3)3[InBr6] (1) was successfully prepared (Tc = 288 K). As expected, the Tc is successfully improved from 248 K of (C2H5NH3)3[InBr6] to 288 K of (BrC2H4NH3)3[InBr6], effectively regulating the phase transition temperature. The variable-temperature structure elucidation suggests that the disorder degree transitions of (BrC2H4NH3)+ cations triggers the phase transition. The introduction of heavier atom (Br) and Br···Br interaction increases the rotational energy barrier of the (BrC2H4NH3)+ cation, which leads to the enhancement of the phase transition temperature. In addition, compound 1 shows dielectric anomalies near Tc, which is consistent with DSC result. This work provides an effective method for further expanding the application range of phase transition materials.