title: Singlet energy transfer as the main pathway in the sensitization of near-infrared Nd3+ luminescence by dansyl and lissamine dyes.
abstract: 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.
authors.affiliation: Laboratories of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Hebbink
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Klink
authors.forename: Lennart
authors.initials: L
authors.lastname: Grave
authors.forename: Patrick G B
authors.initials: PG
authors.lastname: Oude Alink
authors.forename: Frank C J M
authors.initials: FC
authors.lastname: van Veggel