A novel coordination network of Tb(III) with 2-hydroxy-trimesic acid showing very intense photoluminescence (original) (raw)
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Inorganic Chemistry Communications, 2010
The synthesis, structural investigation, and photophysical properties of the complex [Tb(TTA) 2 (NO 3 ) (TPPO) 2 ] are reported. Unlike the analog tris-diketonate complex [Tb(TTA) 3 (TPPO) 2 ], the new complex presents abnormally high luminescence intensity centered on the terbium ion. Our results clearly suggest a higher energy transfer efficiency from the TTA antenna ligand to the Tb(III) ion in the bis-diketonate complex compared with that in the tris-diketonate complex. A mechanism involving the increasing of triplet state energy when one TTA ligand is replaced by the NO 3 − group in the first coordination sphere is suggested and experimentally investigated to explain the anomalous luminescence properties of the new complex [Tb(TTA) 2 (NO 3 )(TPPO) 2 ].
Current manufacturing technologies for OLEDs involve the use of expensive high vacuum techniques and call for thermal stability requirements which are not fulfilled by many materials. These problems disappear when the OLED films are deposited directly from solution. In this study, we have synthesized, modelled by semi-empirical quantum chemistry methods and characterized the optical properties of two novel Tb(III) complexes with carboxylic acids, which can be readily used as "complex-only" emissive layers in wet-processed OLEDs. Upon excitation in the UV region, very efficient energy transfer from the ligands to Tb 3+ takes place, giving rise to intense green emission, both in powder and as a thin film. The good quantum efficiencies (31.3% and 24.7%, respectively) and adequate thin film forming properties make these materials promising chromophores for cost-effective OLEDs.
Inorganic Chemistry, 2019
Two discrete mononuclear complexes, [Tb(bbpen)(NO 3)] (I) and [Tb(bbppn)(NO 3)] (II), for which H 2 bbpen = N,N′-bis(2-hydroxybenzyl)-N,N′-bis(pyridin-2-ylmethyl)ethylenediamine and H 2 bbppn = N,N′-bis(2-hydroxylbenzyl)-N,N'-bis(pyridin-2-ylmethyl)-1,2-propanediamine, were synthesized and characterized by FTIR, Raman, and photoluminescence (PL, steady-state and time-resolved modes) spectroscopy. The attachment of a methyl group to the ethylenediamine portion of the ligand backbone differentiates II from I and acts as a determining feature to both the structural and optical properties of the former. The single-crystal X-ray structure of H 2 bbppn is described here for the first time, while that of complex II has been redetermined in the monoclinic C2 space group in light of new diffraction data. In II, selective crystallization leads to spontaneous resolution of enantiomeric molecules in different crystals. Absolute emission quantum yields (ϕ) and luminescence excited-state lifetimes (at room temperature and 11 K) were measured for both complexes. Despite their similar molecular structures, I and II exhibit remarkably different ϕ values of 21 ± 2% and 67 ± 7%, respectively, under UV excitation at room temperature. Results of quantum-mechanical (DFT and TD-DFT) calculations and experimental PL measurements also performed for H 2 bbpen and H 2 bbppn confirmed that both ligands are suitable to work as "antennas" for Tb III. Considering the 5 D 4 lifetime profiles and the significantly higher absolute quantum yield of II, it appears that thermally active nonradiative pathways present in I are minimized in II due to differences in the conformation of the ethylenediamine bridge.
Monomer and metallopolymer compounds of Tb(III) as precursors for OLEDs
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Inorganica Chimica Acta, 2014
ABSTRACT Three ternary lanthanide complexes with o-bromobenzoic (o-BrBA), o-chlorobenzoic acid (o-ClBA) and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) have been synthesized. These complexes were characterized by elementary analysis, UV absorption spectroscopy and IR spectroscopy. The crystal structures of [Tb-2(TPTZ)(2)(o-BrBA)(4)(NO3)(2)(H2O)(2)] (1), [Tb-2(TPTZ)(2)(o-ClBA)(3)(NO3)(2)(H2O)(3)]center dot o-ClBA center dot C2H5OH center dot 2H(2)O (2) and [Sm-2(TPTZ)(2)(o-ClBA)(4)(NO3)(2)(H2O)(2)] (3) were determined by single-crystal X-ray diffraction, and they were all dinuclear complexes with the characteristic of triclinic and P-1 space group. The crystals 1 and 3 were isostructural, whose center ions were bridged by mu(2)-o-BrBA /mu(2)-o-ClBA ions and the coordinate number of the central metal ions were nine, composed by a eta(3)-TPTZ, two bridging bidentates and one monodentate o-BrBA (o-ClBA) ligand, a bidentate NO3 and a coordinated water molecule. But the structure of complex 2 was asymmetric and the two Tb(III) ions have different coordination surroundings. Furthermore, the luminescence spectra and luminescence lifetimes of three crystals were then measured. Besides, the two Tb(III) complexes exhibit high emission quantum efficiencies.
Journal of Coordination Chemistry, 2018
Synthesis and properties of new luminescent amphiphilic Tb(III) complexes [TbL 3 Á2H 2 O]Á3H 2 O, TbL 3 Ábipy, [H 3 O][TbL 4 ]Á6H 2 O and [H 3 O][TbL 0 3 L]ÁH 2 O, where HL is 1-phenyl-3-methyl-4-stearoylpyrazolone-5 and HL 0 is 1-phenyl-3-methyl-4-formylpyrazolone-5, are reported. The complexes have been characterized by elemental and thermal analysis, FTIR and luminescence spectroscopy methods. Formation and properties of Langmuir-Blodgett films of the complexes are described.
Helvetica Chimica Acta, 2002
Two macrobicyclic ligands derived from an 18-membered tetralactam ring and 2,2'-bipyridine or 2,6bis(pyrazol-1-yl)pyridine moieties, 1 and 2, respectively, form stable complexes with Gd III , Eu III , and Tb III ions in aqueous solution. The ligand-based luminescence is retained in the Gd III cryptates, whereas this radiative deactivation is quenched in the Eu III and Tb III cryptates by ligand-to-metal energy transfer, resulting in the usual metal-centered emission spectra. Singlet-and triplet-state energies, emission-decay lifetimes, and luminescence yields were measured. [Tb & 1] 3 cryptate shows a long luminescence lifetime (t 1.12 ms) and a very high metal luminescence quantum yield (F 0.25) in comparison with those reported in the literature for Tb 3 complexes sensitized by a bipyridine chromophore. By comparison to [Ln & 1] 3 , [Ln & 2] 3 presents markedly lower luminescence properties, due to worse interaction between the 2,6-bis(pyrazol-1-yl)pyridine unit and the metal ion. Moreover, the luminescent metal and the triplet ligand energy levels of [Eu & 2] 3 do not match. The effects of H 2 O molecules coordinated to the metal centre and of thermally activated decay processes on nonradiative deactivation to the ground-state are also reported.
The synthesis and photoluminescent properties of Ln(III)-TTA complexes (Ln¼ Eu(III) and Sm(III) ions; TTA ¼ 3-thenoyltrifluoroacetonate) with N-methyl-ε-caprolactam (NMC) are reported. The Ln complexes were characterized by elemental analysis, complexometric titration with EDTA and infrared spectroscopy. The molecular structures of the [Eu(TTA) 3 (NMC)(H 2 O)] and [Sm(TTA) 3 (NMC)(H 2 O)] Á H 2 O compounds were determined by single crystal X-ray crystallography. In these structures, the three TTA molecules are coordinated to the metal in anionic form as bidentate ligands, while the H 2 O and NMC molecules are coordinated to the metal in neutral form as monodentated ligands. The coordination polyhedron around the Ln(III) atom can be described as square antiprismatic molecular geometry. The geometry of the [Eu(TTA) 3 (NMC)(H 2 O)] complex was optimized with the Sparkle/RM1 model for Ln(III) complexes, allowing analysis of intramolecular energy transfer processes of the Eu(III) compound. The spectroscopic properties of the 4f 6 intraconfigurational transitions of the Eu(III) complex were then studied experimentally and theoretically. The low value of emission quantum efficiency of 5 D 0 emitting level (η) of Eu (III) ion (ca. 36%) is due to the vibrational modes of the water molecule that act as luminescence quenching. In addition, the luminescence decay curves, the experimental intensity parameters (Ω λ), lifetimes (τ), radiative (A rad) and non-radiative (A nrad) decay rates, theoretical quantum yield (q cal) were also determined and discussed.
Novel terbium luminescent complexes with o-phosphorylated phenolate ligands
Inorganic Chemistry Communications, 2012
Lanthanide complexes with ortho-phosphorylated phenolate ligands LnL 3 (Ln = Eu, Tb, Lu; HL 1 =2-di(p-tolyl) phosphorylphenol; HL 2 = 2-diphenylphosphoryl-4-ethylphenol) were synthesized for the first time and characterized by elemental analysis, FTIR, 1 H, 31 P NMR spectroscopy, LDI-TOF mass-spectrometry. The energy gap between the triplet energy level and the corresponding resonance level of a lanthanide ion ( 5 D 1 for Eu 3+ and 5 D 4 for Tb 3+ ) is optimal for luminescence sensitization of only terbium ions. Bright green photo-and electroluminescence of terbium complexes was demonstrated.