Synthesis, spectral studies and antioxidant study of metal-coordinated azo-dye of pyridine and its analytical application for spectrophotometric micro-determination of copper(II)

A novel azo dye ligand namely (2-(pyridin-3-yldiazenyl)naphthalen-1-ol (HPYNA), was synthesized by the coupling reaction of diazonium salt of 3-aminopyridine with naphthol. The palladium(II) complex for HPYNA ligand was prepared by reacting palladium(II) ions with the HPYNA ligand. These synthesized compounds were characterized using different techniques, including mass, 1H-NMR, infrared, and UV-Vis spectroscopy. The infrared results show that the azo ligand reacts as a bidentate via the oxygen atom of phenol and nitrogen atom of the azo group. The palladium(II) complex is square-planer with diamagnetic properties depending on the results of electronic transitions and magnetic sensitivity. The HPYNA ligand and palladium complex showed significant activity as antioxidants by DPPH method. Trace levels of copper in synthetic urine sample can be successfully determined using the validated method. And finally, the proposed method showed selectivity, in addition to have high accuracy and control. KEY WORDS: Azo dye, Naphthol, DPPH, Palladium(II) complex, Synthetic urine Bull. Chem. Soc. Ethiop. 2025, 39(7), 1273-1282. DOI: https://dx.doi.org/10.4314/bcse.v39i7.4