1. Department of Chemistry and Biochemistry and Centre for Research in Nanoscience; Concordia University; 7141 Sherbrooke Street West, QC H4B 1R6 Canada
2. Institut de Recherche de Chimie-Paris, UMR 8247 CNRS; Chimie-ParisTech; Paris F-75231 cedex 05 France
3. Luminescence Materials Research Group; Faculty of Applied SciencesDelft University of TechnologyMekelweg 15; NI-2629 JB Delft The Netherlands