Synthesis and Characterization of New Azo dye and applications in colorimetric analysis of trace metal ions in Aqueous Medium

Abstract

The chelation behavior of azo dye HL derived from coupling 4-nitrophenyl diazonium salt with 7-hydroxycoumarin with Cd (II), Hg(II) and Fe (III) metal ions has been studied. Reaction of the azo dye with Cd (II) and Hg(II) ions at different pH gave new two complexes. At pH=8, complex of the formula [Cd(L)2]Cl2 was formed while at pH=4.5, the complex [Cd(L) Cl2]. 2H2O was obtained. Another two new complexes of the formula [Fe(L)2Cl2]Cl.2H2O have been obtained from the reaction of aqueous solution of the azo dye with FeCl3.6H2O. All the above preparations were performed after fixing the optimum pH and molar concentration. Wide range of molar concentrations was investigated and the concentration which obeyed the Lambert-Beer’s Law, was chosen. The effects of time on the stability of these complexes were checked. The stoichiometry of the above prepared complexes was determined using mole ratio and Job methods. A great bathochromic shift was observed in the UV–Vis absorption spectra of (10-6-10-8 mole/lit.) of an aqueous solution of the solid complexes. The vibration spectra of these complexes gave different changes compared to that of the free ligand. The 1H NMR spectra for one of the complexes were also performed.