Crystal structure, phase transitions, optical and electrical properties in a new Cu-halide organic-inorganic hybrid

Single crystals of a new hybrid metal halide [C7H16N2][CuCl4] were grown by hydrothermal technique and characterized by single-crystal X-ray diffraction, IR and Raman spectroscopy, optical absorption, differential scanning calorimetry and dielectric measurements. The compound [C7H16N2][CuCl4] crystallizes in the monoclinic space group P2(1)/c at room temperature. In the molecular structure, the tet-rachlorocuprate anions are linked to the organic cations through N-H center dot center dot center dot Cl hydrogen bonds. The Raman and IR analyses confirm the presence of the organic groups and the anionic entities. UV-Visible absorption spectrum revealed the energy of the optical band gap. The DSC measurements indicated that [C7H16N2][CuCl4] underwent two sequential phase transitions at around 288 and 388 K. The temperature dependence of the electrical conductivity confirmed the phase transitions that were well detected with differential scanning calorimetry. The analysis of Nyquist plots revealed the contribution of the bulk mechanism and the grain boundaries. (C) 2019 Elsevier B.V. All rights reserved.