1. Medicinal Chemistry, Department of Biological Sciences, Faculty of Exact Sciences, National University of La Plata, 47 and 115, La Plata B1900BJW, Argentina, Walther Cancer Research Center and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, and Università degli Studi di Firenze, Polo Scientifico, Laboratorio di Chimica Bioinorganica, Rm. 188, Via della Lastruccia 3, 50019 Sesto Fiorentino (Florence), Italy