1. LCPO−CNRS−ENSCPB, Bordeaux University (UMR 5629), 16 Avenue Pey Berland, 33607 PESSAC Cedex, France, UEM−DFF, Department of Pharmacy and Pharmacology, Maringá State University, CEP 87020-900 Maringá, Paraná, Brazil, Chemistry Department, Stanford University, Stanford, California, and CERMAV−CNRS, Joseph Fourier University, B. P. 53, F-38041 Grenoble Cedex, France