New azo ligands containing azomethine groups in the pyridazine-based chain: Synthesis and characterization

Five, novel pyridazine-based azo chromophores were synthesized by the condensation reaction of 3,6-bis((aminoethyl)thio)pyridazine with 5-(4-X-phenyl)-azo-salicylaldehyde (X = NO2, Cl and Et), 5-(2,4-di-Cl-phenyl)-azo-salicylaldehyde and 5-(3,4-di-Cl-phenyl)-azo-salicylaldehyde. The dyes were characterized by elemental analysis, thermal analyses, IR, UV–vis, NMR and mass spectroscopy. Spectral characteristics of the dyes were investigated in four organic solvents of differing polarity; thermal studies indicate that the framework of dyes is stable up to 220 °C. Complexation of the azo dyes with Cu(II) gave subtle changes in their absorption spectra.