A Cu(II) complex based on a Schiff base ligand derived from Ortho-vanillin: Synthesis, DFT analysis and catalytic activities

Abstract

The synthesis of a new Cu(II) complex with a bidentate Schiff base is presented. The ligand L was characterized using 1H NMR, 13C NMR, IR and UV–Visible spectroscopy techniques. Structural analysis of CuL2 was carried out using single crystal X-ray diffraction in which the copper center adopts a square planar geometry with two naphthyl substituents perpendicular to the molecular plane. The structure has been further analyzed by IR and UV–Visible spectroscopy techniques. Density functional theory (DFT) and TD-DFT studies provided further information on the structural features and electronic transitions of CuL2. The catalytic activity of CuL2 was investigated in the oxidation of selected primary and secondary alcohols. These reactions were carried out in the presence of various oxidants such as oxygen, hydrogen peroxide or tert‑butyl hydroperoxide (TBHP) and additives such as sulphuric acid, acetic acid and imidazole. The oxidant/additive combination of TBHP and imidazole was shown to be effective for the oxidation process, and the degree of their impact on the oxidation reaction is highly dependent on a balanced ratio between them.