Synthesis, Characterization and Antibacterial Activity of New Complexes of Some Lanthanide Ions with 15-Crown-5 and 18-Crown-6

Complexes of some lanthanide picrates (Ln(3+) = Nd3+ and Dy3+) with 15-crown-5 and 18-crown-6 were synthesized and characterized by elemental analysis, ICP-AES, FTIR, H-1-NMR, C-13-NMR and UV-Visible spectrophotometric methods, thermal analysis (TGA & DTG), magnetic susceptibility, molar conductance and melting points. Also an in-vitro study on pathogenic gram positive (Staphylococcus aureus) and pathogenic gram negative bacteria (Escherichia coli, Salmonella and pseudomonas aeruginosa) was performed and the results were compared to those of a broad spectrum antibiotic (Chloramphinicol). The complexes of 15-crown-5 have the general formula [Ln(15C5)(2)(Pic)]Pic(2)center dot nH(2)O where (Ln(3+) = Nd3+ and Dy3+), (Pic = Picrate anion) and (n = 2 or 4) except for Pr3+ complex which has the formula [Pr(15C5)]Pic(3)center dot H2O, the 18-crown-6 complexes have the general formula [Ln(18C6)]Pic(3) where (Ln(3+) = Pr3+ and Nd3+) except for Dy3+ complex which has the formula [Dy(18C6)(Pic)]Pic(2)center dot 3H(2)O. In 15-crown-5 complexes both Nd3+ and Dy3+ were coordinated with two 15-crown-5 ligands and one picrate anion through its phenolic oxygen and the oxygen of it's ortho nitro group, except for Pr3+ which was coordinated with only one 15-crown-5 ligand leaving three picrate anions as counter ions. In 18-crown-6 complexes both Pr3+ and Nd3+ were coordinated with one 18-crown-6 ligand leaving all the three picrate anions as counter ions outside the coordination sphere, except for the Dy3+ complex which was coordinated with one 18-crown-6 ligand and one picrate anion.