Synthesis, spectroscopic studies, X-ray powder diffraction data and antibacterial activity of mixed transition metal complexes with sulfonate azo dye, sulfamate and caffeine ligands

The ligand azo dye (L) [disodium (7-hydroxyl-8-phenylazo-1,3-naphthalenedisulfonate)] and its complexes of the formula [M L(S) (caf)]; M = Cd(II), Ni(II), Cu(II) and Zn(II); S = sulfamate; Caf = caffeine are prepared and characterized by molar conductance, infrared, H-1, C-13, NMR, EPR,UV-visible and X-ray Powder Diffraction (XRD). Correlations of all spectroscopic data suggest that azo dye (L) acts as bidentate ligand with (NO) sites; the caffeine and sulfamate behave as a monodentate ligand with N9 and oxygen donor towards metal ions respectively. The molar conductance reveals that the new series of the metal complexes are non-electrolytes. The postulated tetrahedral structure of the obtained complexes is also confirmed by the spectroscopic data analysis. The antibacterial activity of the complexes was tested against pathogenic strains using agar disk diffusion method.