Substituted Phenanthrolines as Antennae in Luminescent Eu III Complexes (original) (raw)
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Molecules, 2021
New antenna ligand, 2-(phenylethynyl)-1,10-phenanthroline (PEP), and its luminescent Eu (III) complexes, Eu(PEP)2Cl3 and Eu(PEP)2(NO3)3, are synthesized and characterized. The synthetic procedure applied is based on reacting of europium salts with ligand in hot acetonitrile solutions in molar ratio 1 to 2. The structure of the complexes is refined by X-ray diffraction based on the single crystals obtained. The compounds [Eu(PEP)2Cl3]·2CH3CN and [Eu(PEP)2(NO3)3]∙2CH3CN crystalize in monoclinic space group P21/n and P21/c, respectively, with two acetonitrile solvent molecules. Intra- and inter-ligand π-π stacking interactions are present in solid stat and are realized between the phenanthroline moieties, as well as between the substituents and the phenanthroline units. The optical properties of the complexes are investigated in solid state, acetonitrile and dichloromethane solution. Both compounds exhibit bright red luminescence caused by the organic ligand acting as antenna for sensi...
lanthanide phen complexes, 2024
All chemicals used were of analytical reagent grade, including 1,10-phenanthroline, lanthanum oxide, europium oxide, hydrochloric acid, and ethanol, with deionized/doubly distilled water employed throughout the experiments using Grade A glassware. Europium chloride was prepared by dissolving europium oxide in 5 M HCl, and the resulting EuCl3 solution was added slowly to an ethanolic solution of 1,10-phenanthroline under stirring at 50°C for few hours, forming a light pink precipitate of the Eu-phen complex, which was isolated, washed with water and ethanol, and dried to obtain the solid product in 75-80% yield. The La-phen complex was synthesized similarly by reacting in-situ generated LaCl3 with 1,10-phenanthroline in ethanol, followed by precipitation, washing, and drying to get an off-white powder in 70-75% yield. UV-vis spectra of Eu-phen were recorded in aqueous solution showed two peaks with absorption maxima for at 263.8 and 227.8 nm, corresponding to the intraligand π→π* transitions of the phenanthroline ligand, slightly red-shifted compared to free phenanthroline due to coordination to Eu confirming the formation of complex. while for La-phen, peaks were seen at 262.0 and 231.9 nm (π→π* transitions) and an additional peak at 375.2 nm due to ligand-to-metal charge transfer (LMCT) from the phen ligand to the 5d orbital of La(iii). Photoluminescence studies showed the Eu-phen complex exhibited characteristic emission bands at 608, 610, 615, and 617 nm, corresponding to the 5D0 → 7FJ (J = 1, 2, 3, 4) transitions of the Eu3+ ion, with the intensity pattern, particularly the strong 5D0 → 7F2 band at 616 nm, indicating a non-centrosymmetric coordination environment around Eu3+, and additional peaklets at 577 and 589 nm suggesting perturbation of the local environment by the coordinated ligand, while the La-phen complex showed emission bands at 362 and 380 nm, likely due to LMCT or other metal-centered transitions influenced by 1,10-phenanthroline coordination, with a peaklet at 535 nm further indicating modification of electronic transitions upon complexation. SEM images revealed an agglomerated morphology for La-phen, consisting of irregularly shaped particles formed by aggregation of rod-like structures, while Eu-phen exhibited an agglomerated morphology forming irregular, plate-like structures randomly oriented and stacked. EDS analysis confirmed the expected elemental compositions, with the experimental and theoretical values matching closely for the proposed empirical formulas: La-phen: C36N6O3La (C 62.4%, N 7.9%, O 20.8%, La 6.3%) and Eu-phen: C36N6O3Eu (C 54.9%, N 3.8%, O 27.6%, Eu 10.6%), with EDS mapping showing homogeneous distribution of elements, indicating high purity of the complexes. The FT-IR spectra exhibited characteristic vibrational bands corresponding to the phenanthroline ligands and coordinated functional groups, with bands for La-phen at 1631 and 1519 cm-1 assigned to aromatic C=C and C=N stretches of phen, bands at 850 and 726 cm-1 attributed to out-of-plane C-H bending vibrations, a broad band at 3420 cm-1 indicating O-H stretching from coordinated hydroxides and hydration water, and the band at 1385 cm-1 confirming the presence of coordinated chloride counterions, with similar vibrational bands observed for Eu-phen, with slight shifts in band positions due to the difference in ionic radii and coordination preferences of the lanthanide centers. The UV-vis, photoluminescence, SEM-EDS, and FT-IR data collectively support the successful synthesis and coordination of the 1,10-phenanthroline ligand to the lanthanum and europium centers, forming the respective lanthanide complexes, with the spectroscopic data providing insights into the electronic transitions, coordination environment, and bonding interactions within the complexes, and the emission properties of the Eu-phen complex, with its characteristic Eu3+ emission bands in the visible region, and the La-phen complex, with its ligand-centered emission, suggesting potential applications in luminescent materials and photonic devices, while further time-resolved spectroscopic studies are proposed to better understand the excited-state photophysics governing the luminescence properties of these complexes, contributing overall to the understanding of the structural and photophysical properties of lanthanide-phenanthroline coordination compounds and laying the foundation for designing complexes with optimized luminescent output.
European Journal of Inorganic Chemistry, 2011
Crystal structures and vibrational and electronic spectroscopic data are reported for europium(III) complexes with 5(or 4)-R-1,10-phenanthroline (phen) ligands (R = chloro, methyl, nitro, amino). All complexes comprise a 10-coordinate Eu 3+ ion with three chelating nitrato anions and two bidentate phen ligands. The crystal structures are of three distinct types with space groups C2/c, P2 1 /n and P1. The roomtemperature emission spectra are dominated by the forced electric dipole 5 D 0 Ǟ 7 F 2 emission of Eu 3+ . The excitation spectra show that the triplet donor state of the nitro-substituted complex has a lower energy than the other complexes and the lower luminescence quantum efficiency of this complex is rationalized. The emission spectra recorded at 10 K [a]
Chemical Physics, 2011
In this work, it were performed computational design and synthesis of a new luminescent Eu(III) complex with the usual 1,10-phenanthroline ligand substituted in the 4 and 7 positions by chlorine atoms, which one has shown a higher luminescent output than that of the non-substituted analogous complex. The molecular structures for all complexes using the Sparkle and DFT methods were obtained, such as their coordination bond distances with values in a typical range. Analyzing the direct Eu(III) ion excitation for the phenCl complex, all of them are red shifted in comparison to the one of the phen complex suggesting that the ion environment is more polarizable in the first case, this corroborate with results obtained for intensities and R02 parameters.
Polyhedron, 2013
A new coordination compound of Eu(III) with 1-methyl-1,10-phenanthroline-2(1H)-one (L) as a ligand has been synthesized and characterized using infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. The structure contains isolated [Eu(L) 3 (NO 3 ) 3 ] molecules interacting through extensive p-stacking. Photoluminescence studies demonstrate that the complex shows line-like emission characteristic of Eu(III) when excited in the ligand-centered absorption bands, with a quantum yield of 22% and a lifetime of 0.74 ms.
Asian Journal of Chemistry, 2014
The complex [Eu(L)3(phen)] (where L = 2'-hydroxy-4'-methoxy-2-phenylacetophenone, phen = 1,10-phenanthroline) was synthesized and characterized, by elemental analysis, energy dispersive X-ray spectroscopy, 1 H NMR spectroscopy infra red spectroscopy, TGA/ DTA, scanning electron microscopy and the excitation as well as emission spectrum. The [Eu(L)3(phen)] had regular shaped particles with size less than 1 µm without any phase separation and on excitation at 344 nm emits bright red luminescence with main peak at 614 nm. The complex emitting red luminescence might be used to make the electroluminescent devices for display purposes.
Novel Luminescent Eu 3+ -Indandionate Complexes Containing Heterobiaryl Ligands
Journal of the Brazilian Chemical Society, 2014
Novos complexos indandionatos de fórmulas [Ln(aind) 3 L(H 2 O)] e [Ln(bind) 3 L]•H 2 O, (L: 1,10-fenantrolina (phen) ou 4,7-dimetil-1,10-fenantrolina (dmphen), Ln 3+ : Eu 3+ ou Gd 3+ , aind: 2-acetil-1,3-indandionato e bind: 2-benzoil-1,3-indandionato) foram sintetizados e caracterizados por análise elementar, espectroscopia de absorção na região do infravermelho e análise termogravimétrica. Os dados de caracterização são consistentes com a presença de uma molécula de água de cristalização nas estruturas dos compostos [Ln(bind) 3 L]•H 2 O, enquanto que nos complexos [Ln(aind) 3 L(H 2 O)] a molécula de água atua como ligante. As geometrias dos complexos do íon Eu 3+ , otimizadas pelo modelo SPARKLE/AM1, foram consistentes com os resultados experimentais de luminescência. As propriedades luminescentes dos compostos de Eu 3+ são discutidas em termos de parâmetros de intensidade experimentais (Ω 2 e Ω 4), taxas radiativas (A rad) e não-radiativas (A nrad) e eficiência quântica de emissão (η). Os maiores valores de η foram obtidos para os compostos [Eu(bind) 3 L]•H 2 O, refletindo a ausência de moléculas de água na primeira esfera de coordenação do íon Eu 3+. Novel Ln 3+-indandionate complexes of formulas [Ln(aind) 3 L(H 2 O)] and [Ln(bind) 3 L]•H 2 O (L: 1,10-phenanthroline (phen) or 4,7-dimethyl-1,10-phenanthroline (dmphen), Ln 3+ : Eu 3+ or Gd 3+ , aind: 2-acetyl-1,3-indandionate and bind: 2-benzoyl-1,3-indandionate) were synthesized and characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analyses. The characterization data are consistent with the presence of a water lattice molecule in the [Ln(bind) 3 L]•H 2 O compounds. However, the data also suggest that the water acts as a coordinated molecule in the [Ln(aind) 3 L(H 2 O)] ones. Theoretical geometries of the Eu 3+-complexes have been optimized via the SPARKLE/AM1 Model for lanthanide complexes that are consistent with their luminescence experimental data. The photoluminescence properties of the Eu 3+-compounds have been discussed in terms of experimental intensity parameters (Ω 2 and Ω 4), radiative (A rad), and non-radiative (A nrad) spontaneous emission coefficients. The higher values of emission quantum efficiency (η) of the [Eu(bind) 3 L]•H 2 O compounds reflect the absence of luminescence-quenching water molecule in their first coordination spheres.
2010
New lanthanide complexes with 4,5-bis(diphenyl)phosphoranyl-1,2,3-triazolate (L-), LnL 3 3 nH 2 O (1-8) and LnL 3-(phen) 3 nH 2 O (9-16) (Ln = La, Ce, Nd, Sm, Eu, Gd, Tb, Er), have been prepared and spectroscopically characterized. The structures of LnL 3 3 nH 2 O (Ln = La, Ce, Nd, Sm and Gd) were determined by X-ray crystallography. The metal centers exhibit a distorted trigonal dodecahedron coordination environment with two symmetrically O,O-bidentate ligands and one unsymmetrically O,N-ligand attached to the metal; two oxygen atoms from neighboring dimethyl sulfoxide (DMSO) molecules complete the coordination sphere. This unsymmetrical ligand coordination behavior was also identified in solution through 31 P{ 1 H} NMR studies. Photoluminescence spectroscopy experiments in CH 2 Cl 2 for both types of complexes containing Eu(III) (6, 14) and Tb(III) (7, 15) exhibit strong characteristic red and green emission bands for Eu(III) and Tb(III), respectively. Furthermore, NdL 3 (phen) 3 5H 2 O (11) displays emission in the near-infrared spectral region (4 F 3/2 f 4 F 9/2 at 872 nm and 4 F 3/2 f 4 F 11/2 at 1073 nm). The complexes containing 1,10-phenantroline exhibit higher quantum yields upon excitation at 267 nm, indicating that this auxiliary ligand promotes the luminescence of the complexes; however, luminescence lifetimes (τ) in this case are shorter than those of the LnL 3 3 nH 2 O series.
Inorganic Chemistry Communications, 2001
A new europium (III) complex, EuNO 3 6 fHphen 6 Á 2NO 3 Á NO 3 g (1) was prepared and structurally characterized in which Eu 3 is 12-coordinated to six bidentate nitrates. The coordination polyhedron around Eu 3 was described as a slightly distorted icosahedron. The six mono-protonated 1,10-phenanthrolines do not coordinate to the Eu 3 directively due to the formation of hydrogen bonds in form of OÁ Á ÁH±N with two nitrates and also the formation of two face-to-face trigonal plates within which one free nitrate is sandwiched. 1 exhibits strong red and blue¯uorescence when it was irradiated by UV light. Ó
Polyhedron, 2006
Two new Eu(III) complexes featuring 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate (hfac) and a rigid Lewis base ligand 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz), ½EuðhfacÞ 2 ðH 2 OÞðEtOHÞðtptzÞ½CF 3 CO 2 À (1) and Eu(hfac) 3 (tptz) (2), were synthesized. Their structures were established by single crystal X-ray diffraction. The europium ion in each of these complexes is nona-coordinate with six oxygen and three nitrogen atoms forming a coordination polyhedron best describable as a monocapped square antiprism. The difference in the composition and structure between these two complexes is caused by simply reversing the order of ligand (hfac and tptz) addition during the complex synthesis, and is rationalized in terms of the structural and electronic properties of the ligands and the overall steric bulk of the coordination sphere. Both complexes display characteristic Eu(III)-originated red emission upon UV excitation. The high quantum yields observed, 52% (1) and 60% (2), are rationalized in terms of the strong absorptions of both hfac and tptz ligands near the excitation wavelength (295 nm), an interpretation consistent with the well-established mechanism of ligand-mediated energy transfer for lanthanide-based light emission.