| Theoretical and experimental spectroscopic approach of fluorinated Ln(3+)-beta-diketonate complexes. | |
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MedLine Citation:
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PMID: 20617802 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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In this paper we report the synthesis of two new complexes, [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadionate and phen = 1,10-phenanthroline), and their complete characterization, including single-crystal X-ray diffraction, UV-vis spectroscopy, IR spectroscopy, and TGA. The complexes were studied in detail via both theoretical and experimental approaches to the photophysical properties. The [Eu(fod)(3)(phen)] complex crystallizes in the monoclinic space group P2(1)/c. The crystal structure of [Eu(fod)(3)(phen)] exhibits an offset pi-pi stacking interaction between the phenanthroline ligands of adjacent lanthanide complexes. The Eu(3+) cation is coordinated to three fod anionic ligands and to one phen. The symmetry around Eu(3+) is best described as a highly distorted square antiprism. The molar absorption coefficients of [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] revealed an improved ability to absorb light in comparison with the stand-alone phen and fod molecules. [Tb(fod)(3)(phen)] emits weak UV excitation, with this feature being explained by the triplet-(5)D(4) resonance, which contributes significantly to the nonradiative deactivation of Tb(3+), causing a short lifetime and low quantum yield. The intensity parameters (Omega(2), Omega(4), and Omega(6)) of [Eu(fod)(3)(phen)] were calculated for the X-ray and Sparkle/AM1 structures and compared with values obtained for [Eu(fod)(3)(H(2)O)(2)] and [Eu(fod)(3)(phen-N-O)] (phen-N-O = 1,10-phenanthroline N-oxide) samples. Intensity parameters were used to predict the radiative decay rate. The theoretical quantum efficiencies from the X-ray and Sparkle/AM1 structures are in good agreement with the experimental values, clearly attesting to the efficacy of the theoretical models. |
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Authors:
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Edjane R Dos Santos; Ricardo O Freire; Nivan B da Costa; Filipe A Almeida Paz; Carlos A de Simone; Severino A Júnior; Adriano A S Araújo; Luiz Antônio O Nunes; Maria E de Mesquita; Marcelo O Rodrigues |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The journal of physical chemistry. A Volume: 114 ISSN: 1520-5215 ISO Abbreviation: J Phys Chem A Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-07-29 Completed Date: 2010-11-10 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9890903 Medline TA: J Phys Chem A Country: United States |
Other Details:
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Languages: eng Pagination: 7928-36 Citation Subset: - |
Affiliation:
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Department of Chemistry, UFS, 49100-000 Sao Cristovao, SE, Brazil. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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