Investigation of structural, optical and electrical conductivity of a new organic inorganic bromide: [C12H17N2]2ZnBr4

Abstract

A new organic–inorganic hybrid, namely the [C₁₂H₁₇N₂]₂ZnBr₄ compound, has been synthesized and studied by single-crystal X-ray diffraction and optical and complex impedance spectroscopy. It crystallized in the centrosymmetric P2₁/n space group at room temperature. The asymmetric unit is constituted by [ZnBr₄]²⁻ anions, showing slightly distorted tetrahedral geometry, surrounded by four organic (C₁₂H₁₇N₂)⁺ cations. The crystal packing is stabilized by N–H⋯Br and C–H⋯Br hydrogen bonds arranged in a three-dimensional network. The optical absorption measurement confirms the semiconductor nature with a band gap of around 3.94 eV. Additionally, the analysis of Nyquist plots (−Z′′ vs. Z′) shows that the electrical properties of the material are heavily dependent on frequency and temperature, indicating a relaxation phenomenon and semiconductor-type behavior. Reduction in Z′ was observed as a function of temperature and frequency which indicates an increase in ac conductivity and the negative temperature coefficient of resistance. The frequency dependent plots of (−Z′′) show that the electrical relaxation is non-Debye in nature. The ac conductivity spectrum obeys Jonscher's universal power law. The Correlated barrier hopping model CBH has been suggested to agree with the conduction mechanism of σ_ac for the [C₁₂H₁₇N₂]₂ZnBr₄ compound.