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

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 σac for the [C12H17N2]2ZnBr4 compound.