Mechanochemical synthesis and characterization of a nickel(ii) complex as a reversible thermochromic nanostructure

Abstract

In this study, a new thermochromic Ni(II) complex with [(C₃H₇)₂NH₂]₂[NiCl₂(H₂O)₄]Cl₂·2H₂O formula has been synthesized in the solid phase. The complex undergoes a reversible phase transition temperature at thermochromic temperature (T_c), 120 °C, changing its color from green-yellow to dark blue upon heating. The structure and the thermochromic behavior of the complex have been studied using Fourier transform infrared spectroscopy (FTIR), elemental analysis, diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), thermal analysis (TG/DTG/DSC), X-ray diffraction spectroscopy (XRD) and magnetic susceptibility measurements. As the thermochromic reverse process takes place gradually, the spectra analysis and visual inspection before and after transition temperature enables us to monitor the structural changes under heating.