Resorcinol Incorporated Azo Chromophore: Design, Spectral and Biological Investigation of Its Metal Chelates

Azo dye ligands are a class of organic compounds that are widely used as chromophores, in various applications such as dyes, pigments, and sensing materials. Novel transition metal complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Fe(III) incorporating azo chromophore, 3-hydroxy-4-(2,4-dihydroxyphenylazo)naphthalene-1-sulphonic acid (LH) have been synthesized and characterized. Characterization of synthesized ligand and complexes were performed from their microanalysis, magnetic susceptibility, molar conductance, mass spectrometry, fluorescence, vibrational, electronic, 1H-NMR and ESR spectral studies. Mössbauer spectral analysis of Fe(II) complexes are reported. The azo ligand coordinates to various metal entities through O- atom of hydroxy group and N-atom of azo group. The fluorescence studies reveal enhanced emission. Cyclic voltametric studies and nonlinear optical (NLO) properties were reported for representative complexes and ligand. The in vitro biological activity of LH and corresponding complexes were evaluated against Escherichia coli, Staphylococcus aureus, Aspergillus niger and Candida albicans and the results indicate that the complexes have potential biological characteristics. Antioxidant activity of the ligand and complexes was reported using DPPH free radical scavenging technique. The nuclease activity of LH and metal complexes reveal the cleavage of DNA through redox chemistry.