Synthesis, crystal structures, high-temperatures phase transition, optic and electric properties of hybrid halogenometallates: [(CH3)(3)N(CH2)(2)Br](2)[(MBr4)-Br-II] (M = Cu, Zn)

摘要

Two organic-inorganic hybrid compounds [(CH3)(3)N(CH2)(2)Br](2) [(MBr4)-Br-II] (M = Cu, Zn); ((2-bromoethyl) trimethylammonium cations [Br(CH2)(2)N(CH3)(3)](+)) were successfully synthesized with slow evaporation conditions. The structures of the two compounds were determined using single-crystal X-ray diffraction. These materials crystallize in the monoclinic system, space group P2(1)/c. In the molecular arrangement, the [(MBr4)-Br-II](2-) anions are linked to the organic cations through C-H center dot center dot center dot Br hydrogen bonds to form cationanion-cation molecular units, giving a three-dimensional network. The phase transitions, electric and optical properties of [(CH3)(3)N(CH2)(2)Br](2) [CuBr4] (1) and [(CH3)(3)N(CH2)(2)Br](2) [ZnBr4] (2) were carefully characterized. Based on these results, both compounds underwent phase transitions at T-1 = 368 K and T-2 = 385K for (1) and at T-1 = 283K, T-2 = 330K, T-3 = 368K and T-4 = 402K for (2). The optical and electrical properties allow to determinate the gap energy and to characterize the phase transitions. These studies pave the pathway to explore new types of high-phase transition materials with targeted properties for electric and semiconductor applications. (C) 2020 Elsevier B.V. All rights reserved.