An azo-azomethine ligand and its copper(II) complex: Synthesis, X-ray crystal structure, spectral, thermal, electrochemical and photoluminescence properties

• A novel azo chromophore group containing Schiff base ligand its Cu(II) complex were synthesized.
• The ligand and its Cu(II) complex were characterized by spectroscopic and analytical methods.
• Solid state structures of the ligand and its Cu(II) complex were determined by single crystal X-ray diffraction study.
• Electronic and electrochemical properties of the compounds were examined in detail.
• Thermal behaviors of the compounds were also investigated.

In this study, a new azo-azomethine ligand, 4-[(E)-phenyldiazenyl]-2-[(E)-{[4-(propan-2-yl)phenyl]imino}methyl]phenol (HL) and its Cu(II) complex, [CuL2] were synthesized and characterized by the analytical and spectroscopic methods such as elemental analyses, FT-IR, 1H, 13C NMR and mass spectra. Molecular structures of the ligand and its Cu(II) complex were determined by single crystal X-ray diffraction studies. In the structure of the ligand, there is an intramolecular phenol-imine hydrogen bond (O1⋯N1) with a distance of 2.580(3) Å. There are also intermolecular hydrogen bond type interactions CH⋯O and CH⋯NN stabilizing the structure. The crystal structure of the Cu(II) was solved in the triclinic   space group P1¯. In the structure of the complex, the Cu(II) ion is four coordinate bonded to two phenolate oxygens and two imine nitrogens of two ligand molecules in an approximate square-planar geometry. The Cu–O bonds are in trans configuration. Thermogravimetric data revealed that the Cu(II) complex is thermally more stable than the azo-azomethine compound (HL). Upon coordination with Cu(II) ion, both excitation and emission intensities of the ligand shifted to lower values.

A novel azo-azomethine dye, 4-[(E)-phenyldiazenyl]-2-[(E)-{[4-(propan-2-yl)phenyl]imino}methyl]phenol and its Cu(II) complex were prepared and characterized by spectroscopic and analytic methods. Molecular structures of the ligand and its metal complex were also determined by single X-ray diffraction studies. The complex [CuL2] exhibits only one emission band in the 544–555 nm range upon excitation in the 530–560 nm range. Electronic and electrochemical behaviors of the synthesized compounds were also investigated.Figure optionsDownload as PowerPoint slide