Nickel(II), copper(II) and zinc(II) complexes containing symmetrical Tetradentate Schiff base ligand derived from 3,5-diiodosalicylaldehyde: Synthesis, characterization, crystal structure and antimicrobial activity

Novel transition metal complexes of nickel(II), copper(II) and zinc(II) with a symmetrical tetradentate Schiff base, obtained by condensation of 1,3-diaminopropane and 3,5-diiodosalicylaldehyde, N,N′-bis(3,5-diiodosalicylaldehyde)-1,3-diaminoporpane (H2L), have been prepared and characterized by elemental (CHN), FT-IR, UV–Vis and 1H NMR spectroscopic techniques. Out of these, copper (Cu(L)) and zinc (Zn(L)) complexes were isolated in the form of single crystals and characterized by single-crystal X-ray diffraction studies. In the Cu(L) complex, the geometry was found to be slightly distorted square planar, whereas the Zn(L) complex adapted slightly distorted octahedral geometry due to the attachment of two pyridine rings. The antibacterial screening of the prepared compounds was carried out by taking two Gram-positive (Staphylococcus aureus and Bacillus cereus) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The appearance of zones of inhibition clearly depicted that the complexes have more retardation potential as compared to the Schiff base ligand.