[1] Ecole Natl Super Chim Montpellier, CNRS, Heterochim Mol & Macromol UMR 5076, F-34296 Montpellier, France
[2] Ecole Natl Super Chim & Phys Bordeaux, Federat Rech, CNRS, FR 2648,Labs PIOM & IXL, F-33607 Pessac, France
[3] Univ Montpellier 2, UMR 5587, LCVN, F-34095 Montpellier, France
[4] European Mol Biol Lab, F-38042 Grenoble 9, France