1. Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200 F, B-3001 Leuven, Belgium
2. POLY-tech S. Coop.r.l., AREA Science Park, Padriciano, 99, I-34012 Trieste, Italy
3. Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, via L. Giorgieri, 1 I-34127 Trieste, Italy