Structure and Emission Properties of Er₃Q₉ (Q = 8-Quinolinolate)

Abstract

We report the first combined optical and structural investigation of the water free Er-quinolinolate complex, an organo-lanthanide system of interest for 1.5-microm telecom applications. Structural data demonstrate that the complex has a trinuclear structure (Er3Q9) which provides the Er metals with an octa-coordination by the organic ligand and prevents solvent and water molecules from entering the lanthanide coordination sphere. The results of the structural analysis allow us to infer that the strong Er luminescence quenching exhibited by the Er3Q9 complex is due uniquely to resonant energy transfer to the aromatic C-H vibrations of the ligand, providing the correct tools to design more efficient emitters.

Near infrared light emission quenching in organolanthanide complexes

“…We have performed this analysis in Er-quinoline complexes, for which detailed x-ray studies have been reported. 7,13 The comparative study confirms that Eq. ͑4͒ just leads to a negligible underestimation, ϳ10%, of the exact dipole-induced transfer rate, calculated using Eq.…”

“…m-terphenyl-based ͑L͒ Er 3+ complexes ͑ErL͒ and Er-8-hydroxiquinoline ͑Er 3 Q 9 ͒ in the solid state, for which the necessary optical and structural data are available. In ErL, r =1/k r = 4 ms, 2 R min = 3.7 Å, and ͗␣ A ͘ Er ϳ 6.6 cm −1 ; 15,16 assuming a refraction index n ϳ 1.5, the continuum model yields nr =1/k nr ϳ 0.4 s, in good agreement with the measured NIR lifetime, 0.5 s. 2 In Er 3 Q 9 , r = 5 ± 0.5 ms, 17 R min = 3.4 Å, 13 and ͗␣ A ͘ Er = 1 ± 0.3 cm −1 . 18 With these parameters and for n ϳ 1.5, the theoretical nonradiative lifetime becomes nr ϳ 2.6 s, in very good agreement with the experimental emission lifetime, 2.3 s. 13 As predicted by the continuum model, the previous analysis shows that the larger the vibrational absorption at 1530 nm, the faster the nonradiative decay rate of the rareearth complexes.…”

“…In ErL, r =1/k r = 4 ms, 2 R min = 3.7 Å, and ͗␣ A ͘ Er ϳ 6.6 cm −1 ; 15,16 assuming a refraction index n ϳ 1.5, the continuum model yields nr =1/k nr ϳ 0.4 s, in good agreement with the measured NIR lifetime, 0.5 s. 2 In Er 3 Q 9 , r = 5 ± 0.5 ms, 17 R min = 3.4 Å, 13 and ͗␣ A ͘ Er = 1 ± 0.3 cm −1 . 18 With these parameters and for n ϳ 1.5, the theoretical nonradiative lifetime becomes nr ϳ 2.6 s, in very good agreement with the experimental emission lifetime, 2.3 s. 13 As predicted by the continuum model, the previous analysis shows that the larger the vibrational absorption at 1530 nm, the faster the nonradiative decay rate of the rareearth complexes. A further elegant proof of this scaling law is provided by Van Deun's experimental results in solutions of complexes synthesized with the same mononuclear molecular structure, namely, Er-8-quinoline ͑ErQ͒, Er-5-chloro-Q ͑Er5ClQ͒, and Er-5,7-dichloro-Q ͑Er57ClQ͒.…”

Population Saturation in Trivalent Erbium Sensitized by Organic Molecular Antennae

“…Materials synthetic procedures, chemical, structural and photophysical charaterization are described in recent reports. 5,6 The molecular structures of ErClQ 4 and Er 3 Q 9 are shown in Figure 1.…”

“…Erbium lifetimes (τ), ∼2 μs in both complexes (see Table 1), have been previously ascribed to nonradiative deactivation induced by C-H stretching vibrations. 5,6 As a first step to determine Er III sensitization efficiency, we measure the quantum yields (Φ IR ) of the Er III IR emission by the relative method using tris(2,2 0 -bipyridyl)ruthenium(II) ion (Ru(bipy) 3 2þ ; 2.40 Â 10 -3 M) in deaerated water as the reference standard (Φ R = 4.2%, τ = 0.58 μs). 7 The quantum yields is determined as…”