Quenching of Er(III) luminescence by ligand C-H vibrations: Implications for the use of erbium complexes in telecommunications

Copyright 2006 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 89, 111115 (2006) and may be found at

Lanthanoid/Alkali Metal ß-Triketonate Assemblies: A Robust Platform for Efficient NIR Emitters.

The reaction of hydrated lanthanoid chlorides with tribenzoylmethane and an alkali metal hydroxide consistently resulted in the crystallization of neutral tetranuclear assemblies with the general formula [Ln(Ae⋅HOEt)(L)4]2 (Ln=Eu3+, Er3+, Yb3+; Ae=Na+, K+, Rb+). Analysis of the crystal structures of these species revealed a coordination geometry that varied from a slightly distorted square antiprism to a slightly distorted triangular dodecahedron, with the specific geometrical shape being dependent on the degree of lattice solvation and identity of the alkali metal. The near-infrared (NIR)-emitting assemblies of Yb3+ and Er3+ showed remarkably efficient emission, characterized by significantly longer excited-state lifetimes (τobs≈37–47 μs for Yb3+ and τobs≈4–6 μs for Er3+) when compared with the broader family of lanthanoid β-diketonate species, even in the case of perfluorination of the ligands. The Eu3+ assemblies show bright red emission and a luminescence performance (τobs≈0.5 ms, equation image≈35–37 %, ηsens≈68–70 %) more akin to the β-diketonate species. The results highlight that the β-triketonate ligand offers a tunable and facile system for the preparation of efficient NIR emitters without the need for more complicated perfluorination or deuteration synthetic strategies