1. Magnetic Resonance Center (CERM), University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy, Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy, and ProtEra s.r.l., Viale delle Idee 26, 50019, Sesto Fiorentino, Italy