1. Department of Chemistry University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland
2. Centre for Microscopy and Image Analysis University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland
3. SAMS Research Group University of Strasbourg, Institut Charles Sadron CNRS Rue du Loess 23 67200 Strasbourg France
4. Department of Organic Chemistry University of Geneva 30 quai Ernest-Ansermet 1205 Geneva Switzerland