Synthesis, spectroscopic thermal and biological activity studies on azo-containing Schiff base dye and its Cobalt(II), Chromium(III) and Strontium(II) complexes

Schiff base ligand is prepared by condensation of o-amino benzoic acid with 5-phenyl azo-salicyladehyde. The characterization of the ligand is based on elemental analysis, mass spectra and IR spectra. The novel Co(II), Cr(III) and Sr(II) metal complexes are reported and characterized by physico-chemical, spectroscopic methods based on elemental analyses, IR, magnetic moment, and thermal analysis (TGA). The molar conductance data reveals that all the complexes are non-electrolytes. The activation thermodynamic parameters, such as ΔE*, ΔH*, ΔS* and ΔG* are calculated from the DTA curves using Coats–Redfern method. Optical absorption measurements show that the fundamental absorption edge obeys Tauc’s relation for the allowed non-direct transition. Optical band gap (Eg) values equal 2.4, 2.38 and 1.5 eV for Co(II), Cr(III) and Sr(II) metal complexes respectively. The synthesized ligand and its metal complexes were screened for their biological activity against bacterial species, two Gram positive bacteria (Bacillus subtillis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and Pseudomonas aereuguinosa).