1. IMOMEC Division, IMEC, Wetenschapspark 1, SBG/OS, B-3590 Diepenbeek, Belgium; Group Organic and Polymer Chemistry, Limburg Universitair Centrum, Building D, SBG, B-3590 Diepenbeek, Belgium; and Department of Chemistry, AGFA Gevaert, RM-D, Septenstraat, B-2640 Mortsel, Belgium