Synthesis, characterization, and histological activity of novel polydentate azo ligands and their cobalt(II), copper(II) and nickel(II) complexes

We describe the synthesis and characterization of two novel azo ligands, 4,5-dihydroxy-3,6-bis(2-hydroxyphenylazo)-2,7 naphthalene disulfonic acid (H2L) and 4,5-dihydroxy-3,6-bis(2-hydroxy-4-sulfophenylazo)-2,7-naphthalenedisulfonic acid (H2L1). The Cu(II), Ni(II), and Co(II) complexes of these ligands were prepared and characterized by infrared, UV–Vis, 1H- and 13C-NMR spectra, atomic absorption spectroscopy, mass spectrometry, elemental analyses, thermogravimetric analysis, conductivity, cyclic voltammetry, and magnetic measurements. The results suggest that the complexes have a 2:1 (metal:ligand) molar ratio, involving binuclear azo ligands with an ONO donor set. Metal ion uptake studies were conducted with a batch technique. Preliminary histological studies were also made. The results indicate that the azo ligands have high thermal stability, good metal extraction capacity, and favorable dying properties with certain tissues.