Synergy among X-ray crystallography, molecular modeling, thermal analysis, spectroscopic and chemometric methods in the study of rifamycins activity and polymorphism: A. Bacchia, G. Pelizzia, P. Ferrarib and M. Nebulonib,c a) Dipartimento di Chimica Generale ed Inorganica, University of Parma, V. delle Scienze, I-43100 Parma, Italy b) Lepetit Research Center, Via R. Lepetit, 34- I 21040 Gerenzano (VA), Italy. c Present address: Redox snc, Via S.Margherita, 51 - I-20093 Cologno M.se (MI), Italy