Panchromatic Chromophore Mixtures in an AlPO4-5 Molecular Sieve: Spatial Separation Effects and Energy Transfer Cascades


  • The authors are indebted to Dr. K. Hoffmann for the polarization dependent absorption spectra of dye-loaded AlPO4-5 single crystals (Institut für Angewandte Chemie, Berlin). Support by the Volkswagen Foundation under the grant I76160 is gratefully acknowledged.


Dye-loaded AlPO4-5 single crystals were prepared by microwave-assisted hydrothermal synthesis from a batch, containing a mixture of three chromophores (Coumarin 40, Rhodamine BE50, and Oxazine 1) differing in their absorption range, molecular dimensions, and solubilities. Confocal fluorescence images reveal a spatial separation effect of the dye molecules, where the slimmer, more-soluble dye molecule (Coumarin 40) is uniformly distributed in the body of the single crystal, and the bulky and/or less-soluble ones (Rhodamine BE50, Oxazine 1) are situated in distinct domains. Visible spectra show good panchromatic absorption of visible light. Fluorescence lifetime measurements indicate the presence of an energy transfer cascade of the entirely fixed dye molecules from Coumarin 40 to Oxazine 1. The transfer mechanism is predominantly radiative.