Highlighting non-covalent interactions to molecular structure, electronic and vibrational spectra in a new hybrid organic–inorganic cobalt complexes: Synthesis, characterization, experimental and computational studies

The cobalt (II) complexes have been synthesized from the reaction of the cationic entities (1-(2-methoxyphenyl) piperazine and the 1-(4-nitrophenyl) piperazine with metallic salt CoCl₂·6H₂O, then processing the evaporation crystal growth method at room temperature. The synthesized complexes have been fully characterized by single crystal X-ray diffraction, Hirshfeld surface analysis, as well as UV–visible, FTIR spectroscopy, Photoluminescence, and TGA/TDA analysis, and theoretical studies were also performed, in addition to the antioxidant DPPH⁺ radical and ABTS⁺ radical cation assays were performed. The crystal structural analysis reveals that both complexes crystallize in the orthorhombic system. The vibrational absorption bands were identified by infrared spectroscopy. The solid-state UV–visible absorption spectrum of the title compounds was obtained at room temperature to spotlight the optical properties. In the [300–700 K] range, the thermal behaviors were investigated and showed the decomposition of the two complexes with metal complexes residues. Hirshfeld surface analysis cum 2D fingerprint plots visualize the main intermolecular interactions with their contributions in the solid-state phase. The molecular geometries of both complexes obtained from the crystal structure were used for quantum chemical calculation. DPPH⁺ radical and ABTS⁺ radical cation assays were used to highlight the interesting antioxidant activity for both complexes, where the IC₅₀ of compound (1) was greater than 45 mg.mL⁻¹ and it was greater than 49 mg.mL⁻¹ for compound (2). The anticancer activities of the complexes studied were also investigated in silico by molecular docking.