Suppression of Back Energy Transfer by Energy Transfer Between Terbium Ions

Abstract

Suppression of back energy transfer is crucial in realizing efficient luminescent lanthanide complexes. However, the only practical method reported to this day is to raise the energy of the triplet excited state so that back energy transfer is energetically unfavorable, which limits the application where the absorbing wavelength of the organic ligands is important. This chapter explores a radically new strategy that focus on the yield of the back energy transfer as opposed to the rate constant of the back energy transfer. By utilizing energy transfer between lanthanide ions, which is a competitive process to back energy transfer, the contribution of back energy transfer can be suppressed. This chapter describes the theoretical background of this concept using kinetic analysis, and then the experimental confirmation of the proposal using [TbnGd9−n(µ-OH)10(Bu)16]NO3 (n = 0, 1, 2, 5, 8, 9). It is revealed that indeed the contribution of the back energy transfer is suppressed in this cluster, implying the potential of lanthanide clusters as functionalized and efficient luminescent material.