Singlet energy transfer as the main pathway in the sensitization of near-infrared Nd3+ luminescence by dansyl and lissamine dyes.
In general, sensitization of lanthanide(III) ions by organic sensitizers is regarded to take place via the triplet state of the sensitizers. Herein, we show that in dansyl- and lissamine-functionalized Nd3+ complexes energy transfer occurs from the singlet state of the sensitizers to the Nd3+ center. No sensitized emission was observed in the corresponding complexes with Er3+, Yb3+, and Gd3+ ions. Furthermore, the fluorescence of the sensitizers was quenched only in the Nd3+ complex and not in the complexes with the other ions. Only Nd3+ centers can accept energy from the singlet state of the dyes, because the excited states of Nd3+ have a high spectral overlap with the fluorescence of the dansyl and lissamine sensitizers, and because the selection rules allow a fast energy transfer, which apparently is competitive with the fluorescence.
Hebbink
Gerald A
GA
Laboratories of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Klink
Stephen I
SI
Grave
Lennart
L
Oude Alink
Patrick G B
PG
van Veggel
Frank C J M
FC