| Autor: |
Blois L; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil., Costa IF; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil., Honorato J; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil., V Sanches de Araújo A; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil., Ando RA; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil., Carneiro Neto AN; Physics Department and CICECO─Aveiro Institute of Materials, University of Aveiro, Aveiro 3810-193, Portugal., Suta M; Inorganic Photoactive Materials, Institute of Inorganic Chemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany., Malta OL; Department of Fundamental Chemistry, Federal University of Pernambuco, Recife 50740-560, Brazil., Brito HF; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, São Paulo 05508-000, Brazil. |
| Abstrakt: |
Luminescent trivalent lanthanide (Ln 3+ ) complexes are compounds of technological interest due to their unique photophysical properties, particularly anionic tetrakis complexes, given their higher stability and emission quantum yields. However, structural studies on the cation-anion interaction in these complexes and the relation of such to luminescence are still lacking. Herein, the cation-anion interactions in two luminescent anionic tetrakis(2-thenoyltrifluoroacetonato)europate(III) complexes with alkylimidazolium cations, specifically 1-ethyl-3-methylimidazolium and 1-butyl-3-methylimidazolium are investigated. The Eu 3+ complexes were synthesized and characterized by elemental analysis, mass spectrometry, and single-crystal X-ray crystallography, and their luminescence spectra were recorded at 77 K. Quantum chemical calculations were also performed. X-ray crystallography revealed hydrogen bonds between the enolate ligands and imidazolium ring hydrogens. The 1-butyl-3-methylimidazolium complex had two crystallographic Eu 3+ sites, also confirmed by luminescence spectroscopy. The 1-ethyl-3-methylimidazolium complex exhibited an unusual 300 cm -1 splitting in the 5 D 0 → 7 F 1 transition, as reproduced by ligand field calculations, suggesting a stronger hydrogen bonding due to the smaller substituent. We hypothesize that this strong bonding likely causes angular distortions, resulting in high ligand field splittings. |
