1. Rud-er Bošković Institute, P.O.B. 180, HR-10002 Zagreb, Croatia, European Media Laboratory, Villa Bosch, Schloss-Wolfsbrunnenweg 33, D-69118 Heidelberg, Germany, Institut für Physikalische und Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austria, and Department of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, GR-157 71, Athens, Greece