Estudos espectroscópicos e estruturais dos polímeros de coordenação 2D, ∞[Tb(DPA)(HDPA)] e ∞[Gd(DPA)(HDPA)]

Rodrigues, Marcelo O.; Brito-Silva, Antônio M.; Júnior, Severino Alves; Simone, C. A. De; Araújo, Adriano A. S.; Carvalho, Pedro Henrique V. de; Santos, Sílvia Caroline G.; Aragão, Kennedy Alexandre S.; Freire, Ricardo Oliveira; Mesquita, Maria Eliane de

doi:10.1590/s0100-40422009000200004

Cited by 9 publications

(8 citation statements)

References 22 publications

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“…Because the ionic radii of Tb 3+ and Eu 3+ ions are very similar, small variations on cell parameters of the materials were expected. Figures S1 and S2 of the Supporting Information show the final Rietveld refinement plots for (1) and (2) , which unequivocally show that the compounds herein reported and studied are indeed identical to those previously reported. , The supramolecular structure of the materials consists of infinite 2D square-grid-type layers interconnected via offset π–π stacking. Figure depicts the structure of the materials along of b axis, emphasizing the nearest Ln 3+ –Ln 3+ intermetallic distances.…”

Section: Resultssupporting

confidence: 76%

Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Rodrigues

Dutra²,

Nunes

et al. 2012

J. Phys. Chem. C

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In this work, we report a theoretical and experimental investigation of the energy transfer mechanism in two isotypical 2D coordination polymers, ∞ [(Tb 1−x Eu x )(DPA)(HDPA)], where H 2 DPA is pyridine 2,6-dicarboxylic acid and x = 0.05 or 0.50. Emission spectra of ∞ [(Tb 0.95 Eu 0.05 )(DPA)(HDPA)] and ∞ [(Tb 0.5 Eu 0.5 )(DPA)-(HDPA)], (1) and (2), show that the high quenching effect on Tb 3+ emission caused by Eu 3+ ion indicates an efficient Tb 3+ →Eu 3+ energy transfer (ET). The k ET of Tb 3+ → Eu 3+ ET and rise rates (k r ) of Eu 3+ as a function of temperature for (1) are on the same order of magnitude, indicating that the sensitization of the Eu 3+ 5 D 0 level is highly fed by ET from the 5 D 4 level of Tb 3+ ion. The η ET and R 0 values vary in the 67− 79% and 7.15 to 7.93 Å ranges. Hence, Tb 3+ is enabled to transfer efficiently to Eu 3+ that can occupy the possible sites at 6.32 and 6.75 Å. For (2), the ET processes occur on average with η ET and R 0 of 97% and 31 Å, respectively. Consequently, Tb 3+ ion is enabled to transfer energy to Eu 3+ localized at different layers. The theoretical model developed by Malta was implemented aiming to insert more insights about the dominant mechanisms involved in the ET between lanthanides ions. Calculated single Tb 3+ → Eu 3+ ETs are three orders of magnitude inferior to those experimentally; however, it can be explained by the theoretical model that does not consider the role of phonon assistance in the Ln 3+ → Ln 3+ ET processes. In addition, the Tb 3+ → Eu 3+ ET processes are predominantly governed by dipole−dipole (d−d) and dipole−quadrupole (d−q) mechanisms.

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Section: Resultssupporting

confidence: 76%

Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Rodrigues

Dutra²,

Nunes

et al. 2012

J. Phys. Chem. C

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“…This can be explained by the error of ±1000 cm −1 associated with the theoretical method. Noteworthy, this short discrepancy does not disqualify the methodology. ,,, When the lowest triplets of the organic ligands are below the emitter levels of the Ln 3+ ions, fluorescence or phosphorescence arising from the ligand or no emission is normally observed. ,, Indeed the experimental observations demonstrate that the triplet- 5 D 4 resonance contributes significantly to nonradiative deactivation of the Tb 3+ ion and provides a plausible way to justify the short lifetime, 0.23 ms, and quantum yield, q = 28.0%, obtained for [Tb(fod) 3 (phen)].…”

Section: Resultsmentioning

confidence: 97%

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes

et al. 2010

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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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“…O marcador denominado EuDPA foi sintetizado via hidrotermal assistida por micro-ondas (Monowave 300 Anton Paar) em um reator de vidro (Vial Glass) de 10 mL, seguindo uma metodologia descrita por Rodrigues et al 71 Foram misturados 0,35 mmols de Eu(NO3)3 com 0,7 mmols do ligante ácido dipicolínico (H2DPA) (Aldrich, 95%) em 5 mL de água destilada, sob agitação. A reação ocorreu durante 10 minutos a uma temperatura de 160 °C, originando um pó branco.…”

Section: Eudpaunclassified

“…Número de Onda (cm -1 ) compatíveis com o esperado. 69,71,152,153 . As bandas em 1605-1568 e 1485-1437 são referentes ao estiramento simétrico e assimétrico do grupo COO -, respectivamente.…”

Section: Caracterização Dos Marcadores Luminescentesunclassified

“…Na MOF EuDPA, o íon Eu 3+ está coordenado com duas moléculas do ligante, sendo uma parcialmente protonada (HDPA) e outra totalmente desprotonada (DPA). Os ligantes coordenam-se ao metal central através dos átomos de nitrogênio, dos anéis heterocíclicos e pelos oxigênios das carbonilas, atuando como uma espécie de ligante tridentado, conforme demonstrado na Figura 11 69,71. O Eu 3+ possui número de coordenação 8, e geometria antiprisma quadrado distorcido.…”

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Estudo da aplicabilidade dos marcadores luminescentes de disparos de armas de fogo

Arouca¹

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Aos meus pais, avô, esposo e à minha eterna companheira de estudo Biga. iv AGRADECIMENTOS Em primeiro lugar agradeço a Deus, por me conceder força e esperança para continuar a caminhada sempre. Sem Ele, nada faria sentido. Gostaria de agradecer aos meus pais, que sempre me incentivaram a seguir os meus sonhos, sempre instigando e mostrando o caminho certo. Agradeço pela motivação e inspiração que sempre me forneceram. Ao meu esposo e companheiro de vida, Felipe, que compartilhou todos os momentos importantes ao meu lado, sempre me ajudando e me tranquilizando. Você sempre será meu modelo. Te amo. Agradeço também à minha família, em especial meu avô Marcelino e minha avó Odette (in memorian), que sempre irá me acompanhar em mente e coração. Às minhas irmãs caninas, Bia (in memorian) e Biga (in memorian), que sempre estiveram ao meu lado. À Profa. Ingrid pela paciência, confiança e amizade. Obrigada por permitir que eu entrasse no mundo da Química Forense. Ao Márcio, pelo apoio, ensinamentos e discussões. Obrigada pela dedicação na co-orientação e por sua amizade.

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Estudos espectroscópicos e estruturais dos polímeros de coordenação 2D, ∞[Tb(DPA)(HDPA)] e ∞[Gd(DPA)(HDPA)]

Cited by 9 publications

References 22 publications

Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes

Estudo da aplicabilidade dos marcadores luminescentes de disparos de armas de fogo

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Estudos espectroscópicos e estruturais dos polímeros de coordenação 2D, ∞[Tb(DPA)(HDPA)] e ∞[Gd(DPA)(HDPA)]

Cited by 9 publications

References 22 publications

Tb3+→Eu3+ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Tb3+→Eu3+ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln3+−β-Diketonate Complexes

Estudo da aplicabilidade dos marcadores luminescentes de disparos de armas de fogo

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Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Tb³⁺→Eu³⁺ Energy Transfer in Mixed-Lanthanide-Organic Frameworks

Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes