Experimental (FTIR, Raman, UV–visible and PL) and theoretical (DFT and TDDFT) studies on bis(8–hydroxyquinolinium) tetrachlorocobaltate(II) compound

• A new compound “bis (8–hydroxyquinolinium) tetrachlorocobaltate (II)” was synthesized.
• X-Ray diffraction, FTIR and Raman studies were reported.
• UV–Vis Absorption and Photoluminescence technique was used.
• DFT and TDDFT calculations have been incorporated for detailed analysis.
• The organic inorganic Charge Transfer phenomenon was discussed.

The purpose of this paper is to present the chemical preparation, crystal structure, vibrational study and optical features for new organic–inorganic compound [C9H8NO]2CoCl4 abbreviated [8–HQ]2CoCl4. The structural study by X–ray diffraction prove that this compound crystallize in a monoclinic unit–cell with space group C2/c (point group 2/m = C2h). It is built of tetrahedra [CoCl4]2- anions and (C9H8NO)+ cations in the 1/2 ratio. The crystal structure is stabilized by network three–dimensional of NH⋯Cl, NH⋯O, OH⋯Cl, CH⋯Cl hydrogen bonds, and offset π–π stacking interactions. Also, the Hirshfeld Surface projections and Fingerprint plots were elucidated the relative contribution of the type, nature and explore the H⋯Cl, C⋯H, C⋯C, C⋯N, H⋯O intermolecular contacts in the crystal in a visual manner. Furthermore, vibrational analysis of the structural groups in the compound was carried out by both Fourier transforms infrared (FT–IR) and Raman spectra. The spectral data are complemented by good information at the region characteristic of metal–ligand, which evidences coordination through the compound. The optical properties of the crystal were studied by using optical absorption UV–visible and photoluminescence (PL) spectroscopy studies. Theoretical calculations were performed using density functional theory (DFT) at (DFT/B3LYP/LanL2DZ) level in the aim of aiding in studying structural, vibrational and optical properties of the investigated compound. Good relationship consistency is found between the experimental and theoretical studies. Inspection of the optical properties has lead to confirm the exhibition of a green photoluminescence and the occurrence of charge transfer phenomenon in this material.