1. Laboratoire de Synthèse Organique, UMR 6513 CNRS&FR CNRS 2465, Université de Nantes, Faculté des Sciences et des Techniques de Nantes, BP 92208; 2, rue de la Houssinière, 44322 Nantes Cedex 03, France, Chemical Physics, Department of Photochemistry and Molecular Science, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, and Center of Molecular Devices, Department of Chemistry, Royal Institute of Technology, Teknikringen 30, 100 44 Stockholm, Sweden