Regulation of excitation and luminescence efficiencies of europium and terbium benzoates and 8-oxyquinolinates by modification of ligands

Tsaryuk, V. I.; Zhuravlev, Konstantin P.; Zolin, V. F.; Gawryszewska, Paula; Legendziewicz, J.; Kudryashova, V. A.; Pekareva, Irina S.

doi:10.1016/j.jphotochem.2005.06.011

Cited by 66 publications

(60 citation statements)

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“…In a number of cases, there is degradation of a significant part of the energy arriving at the carboxylate levels from the singlet levels of the phenathroline molecule. In particular, in europium and terbium nitrobenzoates, we observed degradation of the energy absorbed by the phenanthroline via the nπ * state of the NO 2 group [9]. The presence of such quenching channels leads to an abrupt drop in the luminescence quantum yield for the Ln 3+ ion.…”

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confidence: 90%

“…The blocking effect of such bridges is observed in the excitation spectra of europium phenylacetate, phenoxyacetate (Fig. 5, curves 3 and 2), and 2-naphthoxyacetate (curve 8), in contrast to the spectra of europium and terbium benzoates (see the figures in [9]) and naphthoates (curve 10). When a bridge is present in the ligand, breaking up the system of conjugated π-electron bonds, there is no broad ligand band in the excitation spectrum.…”

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confidence: 97%

“…In most adducts with phenanthroline, the nπ * and ππ * quenching channels are less efficient than in the corresponding salts or in the nitrobenzoates of europium and terbium with phenanthroline that were studied in [9]. This should be associated primarily with the effect of the methylene bridges, blocking energy transfer from the phenanthroline to the second ligand.…”

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confidence: 97%

“…This leads to an increase in the brightness of luminescence of the adducts compared with the salts. The long-wavelength edge of the band assigned to the Phen and Bpy molecules in the excitation spectra of the Ln 3+ ions lies respectively at 350 nm and 325 nm [9]. For the excitation used, I for the adducts with phenanthroline reaches a value of 300-400, but by selecting the optimal excitation in the range 250-350 nm, it can be increased by an order of magnitude.…”

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confidence: 99%

“…Searching for methods to improve the brightness should be accompanied by study of the processes for excitation of luminescence and energy transfer. The effect of the groups in the ligand on the luminescence spectra, the luminescence excitation spectra, and the luminescence efficiency have been previously discussed for pyridinecarboxylates [5], β-diketonates [6,7], acylpyrazolonates [8], benzoates and 8-hydroxyquinolinates [9] as potential materials for applications. In this work, we have studied the possibility for controlling the luminescence efficiency for three groups of europium and terbium compounds: phenylcarboxylates, naphthylcarboxylates, and indolylcarboxylates.…”

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Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands

et al. 2007

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UDC 535.37We discuss the possibility of optimizing the brightness of luminescence for phenylcarboxylates, naphthylcarboxylates, and indolylcarboxylates of europium and terbium and their adducts with 1,10-phenanthroline and 2,2′-bipyridine by modifying the ligands. We have studied the efficiency of luminescence and luminescence excitation. We consider the effect of blocking energy transfer from the ligands to the Eu 3+ and Tb 3+ ions by methylene (-CH 2 -) bridges dividing the π-electron system of the ligands into two parts and by the electronacceptor nitro group . We have analyzed the pathways for transfer and degradation of the excitation energy at 77 K and 300 K. From the phosphorescence spectra of gadolinium salts, we have determined the energies of the lowest excited triplet states of the ligands. We consider the effect of the relative positions of the triplet levels of the ligands and the excited levels of the Eu 3+ and Tb 3+ ions on the luminescence efficiency. We found channels for dissipation of the excitation energy via the ππ * and nπ * states of the aromatic system of the carboxylate and the NO 2 group.Key words: Eu 3+ ion, Tb 3+ ion, luminescence and luminescence excitation spectra, luminescence efficiency, aromatic carboxylates.Introduction. Many investigations of luminescent materials based on aromatic carboxylates of lanthanides have been connected with their use in analytical chemistry, biology, medical diagnostics, environmental monitoring, etc. These compounds can also be used in organic electroluminescent cells as components forming the emitting layer of the device [1-3]. The major characteristic of luminophores for organic light-emitting diodes is their high brightness.In addition, the compounds should have high volatility or solubility, chemical stability, capability of forming amorphous layers, and in a number of cases they should have significant mobility of the injected charge carriers. An important task is to search for ways to control the brightness of the luminescence of the material and to optimize this brightness by varying fragments of the structure of the compound, changing the nature of the electronic system of the aromatic ligand. For this purpose, groups are introduced into the ligands which have different donor-acceptor capabilities, different sizes and different labilities; the position of the groups in the ligands is varied, and blocking bridging groups are incorporated into the ligands. Optical spectroscopy and modification of the ligands can be used to select compounds for the emitting layer of an electroluminescent device [4]. Searching for methods to improve the brightness should be accompanied by study of the processes for excitation of luminescence and energy transfer. The effect of the groups in the ligand on the luminescence spectra, the luminescence excitation spectra, and the luminescence efficiency have been previously discussed for pyridinecarboxylates [5], β-diketonates [6, 7], acylpyrazolonates [8], benzoates and 8-hydroxyquinolinates [9] as potential materials f...

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Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands

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Sodium Salicylate: An In‐Depth Thermal and Photophysical Study

Spielberg

Campbell

Szeto

et al. 2018

Chemistry A European J

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Sodium salicylate (2-hydroxybenzoate) has been fully characterised by single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis in combination with in operando FTIR spectroscopy and GC-MS, as well as by UV/Vis absorption and photoluminescence spectroscopy backed up by DFT calculations. SCXRD revealed a layered crystal structure composed of ionic sheets formed by Na -O contacts sandwiched between π-stacked aromatic rings of the salicylate anion oriented perpendicular to the layer plane. Only weak van der Waals interactions hold the individual sheets together. No solid/solid or solid/liquid phase transitions were observed upon heating, but a three-step decomposition was observed, with the first onset at 245 °C corresponding to concomitant release of CO and phenol. The UV/Vis absorption spectra show temperature-dependent absorption bands at around 305 and/or 345 nm, which according to DFT calculations correspond to the absorption of the carboxylate or phenolate proton transfer species, respectively. In solution, indications of the phenolate species are found only in a very apolar solvent (cyclohexane). Because of excited-state relaxation, emission always occurs from the phenolate structure, which explains the large Stokes shift.

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Syntheses, Structures, and Luminescence Properties of Lanthanide Coordination Polymers with a Polycarboxylic Terpyridyl Derivative Ligand

Xie

Shu²,

et al. 2014

ChemPlusChem

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Solvothermal reactions of lanthanide chloride with a new ligand, H3L, 4′‐(3‐carboxylpyridyl)‐2,2′:6′,2“‐terpyridine‐6,6”‐dicarboxylic acid, yields seven new lanthanide–organic frameworks: {[Ln2L2]⋅H2O}n (Ln=Pr (1), Nd (2), Sm (3), Eu (4)), {[Ln5L4(COO)3(H2O)4]⋅10 H2O}n (Ln=Tb (5), Dy (6)), and [Yb2L2(H2O)2]⋅2 H2O (7). Single‐crystal X‐ray diffraction reveals that these complexes belong to three structural types. Type I (1–4) consists of lanthanide–carboxyl group layers pillared by L3− to form a three‐dimensional network. Type II (5 and 6) comprises a right‐handed helical chain and a left‐handed helical chain linked through L3− anions into a three‐dimensional framework. Type III (7) is a discrete dinuclear structure. The structural change is due to the decrease in the metal coordination number from nine for the large ions to seven for the small ions; this demonstrates the effect of lanthanide contraction. These materials exhibit high thermal stability. In addition, the luminescent properties of these complexes are discussed.

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Regulation of excitation and luminescence efficiencies of europium and terbium benzoates and 8-oxyquinolinates by modification of ligands

Cited by 66 publications

References 40 publications

Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands

Luminescence efficiency of aromatic carboxylates of europium and terbium when methylene bridges and nitro groups are present in the ligands

Sodium Salicylate: An In‐Depth Thermal and Photophysical Study

Syntheses, Structures, and Luminescence Properties of Lanthanide Coordination Polymers with a Polycarboxylic Terpyridyl Derivative Ligand

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