Crystal structure, spectroscopic, non-linear optical, magnetic properties and DFT studies of bis(2-aminopyridinium) tetrachlorocobaltate(II)

Abstract The crystal structure investigation in room temperature reveals that bis(2-aminopyridinium) tetrachlorocobaltate(II) (1) (abbreviated [2NH2PyH]2[CoCl4]) crystallizes in at monoclinic space group C2/c which is in line with one at 120 K. Fourier transform infrared (FT-IR) and Raman spectra were recorded in order to affirm vibrational modes. The thermal stability of the hybrid crystal analyzed by TG-TDA technique reveals that the title crystal was stable up to 170 °C. Powder XRD diffraction study confirms the crystalline nature and purity of the title salt. The HOMO-SOMO band gap energy of UV–Vis spectrum explains the eventual charge transfer interaction that take mainly place between the anion and [2NH2PyH]+ cation, and the low value (0.48 ev in gas state and 0.68 ev in solid state) indicates the suitability of the crystal for optical application. The first hyperpolarisability (βtot) predicted using DFT is more than one thousand times that of the reference crystal KDP, and the salt shows weak antiferromagnetic interactions.