Metal complexes of azo compounds: Synthesis, characterization, molecular modeling and degradation study by gamma radiation

Abstract

The Fe(III), Co(II) and Cu(II) complexes of three azo compounds namely, 2-(phenylazo)-1-naphtllol (Sudan I) (HL1) a, 4-(phenylazo)-1-naphthol (HL2) b and 2,4-bis(phenylazo)-1-naphthol (HL3) c were prepared and characterized on the basis of their elemental analysis, molar conductance, UV–VIS and FT IR spectroscopic studies. Besides, density functional theory (DFT) computations were conducted to study structures and energetics of the ligands and their complexes. Molecular Electrostatic Potential was also calculated by the DFT method and predicts the most reactive part in the molecule. The isolated complexes are found to have the formulas [Cu(L1)2] a1, [Co(L1)2] a2, [Fe(L1)3] a3, [Cu(HL2)2Cl2].H2O b1, [Co(HL2)(NO3)2].H2O b2, [Fe(HL2)Cl3].H2O b3, [Cu(HL3)Cl2].H2O c1, [Co(HL3)(NO3)2].H2O c2 and [Fe(HL3)Cl3].H2O c3. The IR result showed that the ligand a was chelated with the metal ions in a monobasic bidentate manner, with NO donor sites of the azo nitrogen and the deprotonated phenolic oxygen. While the ligand c was chelated with the metal centers in a neutral bidentate manner and the ligand b was bound with the metal ions as a neutral monodentate donor by azo nitrogen atom. The molecular docking results indicated that the ligands HL1a, HL2b and HL3c may possess significant anti-inflammatory activity. Gamma irradiation of variable concentrations of the ligand solutions HL1a and its complexes [Cu(L1)2] a1, [Co(L1)2] a2 and [Fe(L1)3] a3 was investigated. The color bleaching of the dyes solutions was increase gradually with increasing absorbed dose in the dose range of 3, 5 and 10 kGy.