| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1304067 | Inorganic Chemistry Communications | 2012 | 6 Pages |
Pyrazine bridged dinuclear lanthanide β-diketonate complexes of the type [(tfaa)3Ln(μ-pyz)Ln(tfaa)3] (tfaa is the anion of 1,1,1-trifluoro-2,4-pentanedione; pyz is pyrazine) were isolated by mixing [Ln(tfaa)3] and pyrazine in 2:1 molar ratio in chloroform. The elemental analysis, high yield and only one sharp resonance for the pyrazine moiety in the NMR spectrum are strong enough to support dinuclear complex formation. The oscillator strength of the hypersensitive 4G5/2, 2G7/2 ← 4I9/2 transition of the neodymium complex is approximately two fold higher than the mononuclear [Nd(tfaa)3H2O]. It confirms the presence of two neodymium ions both of which contribute to the oscillator strength. The red and green photoluminescence of Eu–Eu and Tb–Tb complexes, respectively, were scrutinized in solution and discussed.
Graphical abstractPyrazine-bridged dinuclear complexes have been synthesized. One NMR resonance for pyrazine protons supports symmetric bridging of pyrazine to two [Ln(tfaa)3] units. The oscillator strenght of 4f-4f transitions of the dinuclear complex is twofold larger than the values for mononuclear complex. Eu and Tb complexes gives red and green luminescence, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pyrazine-bridged Ln2 complexes of the type [(tfaa)3Ln]2(μ-pyz) are discussed. ► Only one NMR resonance due to pyrazine is observed. ► Red and green photoluminescence are observed from Eu and Tb complexes, respectively. ► The low molecular symmetry around Eu is inferred by stark splitting in the 5D0 → 7F1. ► 5D0 → 7F2/5D0 → 7F1 intensity ratio of [(tfaa)3|Eu(μ-pyz)Ln(tfaa)3] is about 10.89.
