Synthesis, spectroscopic characterization and antibacterial activity of lanthanide-tetracycline complexes

A series of Ln(III)-tetracycline complexes of the type [Ln(TC)Cl-3].2H(2)O [Ln = lanthanum, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium and yttrium; TC = tetracycline] have been synthesized and characterized by analytical, i.r., electronic, H-1-n.m.r. spectral studies, X-ray diffraction and thermogravimetric analysis. A pentagonal bipyramidal structure has been tentatively proposed for the new complexes. The ligand and the new complexes were tested in vitro to evaluate their activity against the bacteria Escherichia coli and Staphylococcus aureus.