Synthesis, characterization, and fluorescence study of phthalhydrazidylazo derivative of an unsaturated diketone and its metal complexes

The coupling of diazotized luminol with the unsaturated diketone 1,7-diphenylhepta-4,6-diene-1,3-dione yielded a new type of tridentate ligand (H_2L). Analytical, IR, ^1H NMR, and mass spectral data indicate the existence of the compound in the intramolecularly hydrogen-bonded keto-hydrazone tautomeric form. Dibasic tridentate coordination of the compound in its [ML(H_2O)] complexes [M = Cu(II), Ni(II) and Zn(II)] was established on the basis of analytical and spectral data. The Ni(II) and Zn(II) chelates are diamagnetic while Cu(II) complex showed normal paramagnetic moment. The fluorescence maxima of the compound in different solvents show that the emission wavelength increases with increases in the polarity of the solvent. The fluorescence intensity in the presence of Cu(II) ion shows a gradual decrease with increases in the concentration of metal ion.