1. Contribution from the Department of Chemistry, University of Southern Denmark (Odense University), Campusvej 55, DK-5230, Odense M, Denmark, Department of Chemistry and Biochemistry, 1 University Station-A5300, The University of Texas at Austin, Austin, Texas 78712-0165, USA, and Chimie, Ingénierie Moléculaire et Matériaux d'Angers, CNRS UMR 6200, Université d'Angers 2 Bd Lavoisier, 49045 Angers, France