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1.
In this paper, ligand effect of several bi-dental oxygen (O) and nitrogen (N) ligands on the red luminescence properties of europium ion (Eu 3+) was studied comprehensively. Absorption, emission, and excitation spectral properties of ternary europium complexes with different combinations of ligands including thenoyl trifluoroacetone (TTA), naphthyl trifluoroacetone (NTA), 2,2′-bipyridyl (bpy) and phenanthroline (Phen) were investigated. Efficient Eu 3+ red emission was observed with all the combinations of the above mentioned ligands. The most intense emission was found with the all nitrogen coordinated complex Eu(bpy) 2(Phen) 2 while the longest wavelength excitation band was recorded with oxygen-nitrogen mixed NTA-bpy complex Eu(NTA) 1(bpy) 3. With change of the ligands combination and ratio, the Eu 3+ emission peak changes slightly from 612 to 618 nm. The absorption and excitation spectra of the europium complexes were compared and analyzed referring to the individual absorption spectral properties of the ligands. The relation between ligand-to-metal charge transfer states and luminescence intensities for different complexes was studied. 相似文献
2.
Binuclear rare earth complexes Ln2L3phen2 (LnIII?=?NdIII, SmIII, EuIII, TbIII, DyIII, YbIII and YIII) with bis-CAPh type ligand - tetramethyl N,N′-(2,2,3,3,4,4-hexafluoro-1,5-dioxopentane-1,5-diyl)bis(phosphoramidate) (H2L) and 1,10-phenanthroline (phen) were synthesized and characterized by elemental analysis, IR, NMR, absorption and luminescence spectroscopy. Luminescence measurements were performed for all the complexes in solid state and for the EuIII, TbIII and YIII complexes - in solution in DMSO as well. The effective energy transfer from organic ligands to LnIII ions strongly sensitizes the LnIII ions emission and under excitation by UV light, the complexes exhibited bright characteristic emission of lanthanide metal centers. It was found that the energy level of the ligands lowest triplet state in the complexes matches better to resonance level of EuIII rather than TbIII ion. Depending on temperature the emission decay times of solid europium and terbium complexes were in the range of 1.5–2.0 ms. In solid state at room temperature the EuIII complex possess intense luminescence with very high intrinsic quantum yield 91% and decay time equal 1.88 ms. 相似文献
3.
The complexation of Eu 3+ with doxycycline (DC) antibiotic in the presence of several second ligands and surfactant micelles of different types is
studied by the spectrophotometric and luminescence methods. It is found that the efficiency of excitation energy transfer
in Eu 3+-DC chelate depends on the nature of the second ligand and surfactant micelles. Using thenoyltrifluoroacetone (TTA) as an
example, it is shown that the second ligand additionally sensitizes the europium fluorescence, and the possibility of intermediate
sensitization of DC and then of europium is shown by the example of 1,10-phenanthroline. In all cases, the excitation energy
transfer efficiency was increased due to the so-called antenna effect. The decay kinetics of the sensitized fluorescence of
the binary and mixed-ligand chelates in aqueous and micellar solutions of nonionic surfactants is studied and the relative
quantum yields and lifetimes of fluorescence are determined. 相似文献
4.
This work reports the synthesis and luminescent properties of complexes of europium(III) with 2-thienyltrifluoroacetonate (HTTA), terephthalic acid (TPA) and phenanthroline (Phen), in the solid state. The new complexes were characterized by elemental analysis, infrared (IR) spectroscopy, scanning electronic microscopy (SEM) and thermal stability analysis. Both binuclear complex Eu 2(TPA)(TTA) 4Phen 2 and polynuclear complex Eu(TPA)(TTA)Phen present better thermal stability than the mononuclear complex Eu(TTA) 3Phen does. The formation of the binuclear/polynuclear structure of the complexes appears to be responsible for the enhancement of the thermal stability. The emission spectra show narrow emission bands that arise from the 5D 0→ 7F J ( J=0-4) transition of the Eu 3+ ion. The spectral data of the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 present only one sharp peak in the region of the 5D 0→ 7F 0 transition indicating that only one Eu 3+ ion species is present in each sample. In addition, the luminescence decay curves of the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 fit a single-exponential decay law. The values of quantum efficiencies of the emitting 5D 0 level for the complexes Eu(TPA)(TTA)Phen and Eu 2(TPA)(TTA) 4Phen 2 are 29% and 28%, respectively. 相似文献
5.
Tetranuclear europium(III) complexes, [Eu 4(μ-O)(L 1) 10] (L 1=2-hydroxy-4-octyloxybenzophenone, 1) and [Eu 4(μ-O)(L 2) 10] (L 2=2-hydroxy-4-dodecyloxybenzophenone, 2) were synthesized by the reaction of lanthanide nitrates with L 1 or L 2 in the presence of triethylamine in methanol. The photosensitized emission bands of the both Eu(III) complexes in THF- d8 were observed around 579, 590, 615, 653, and 699 nm by the excitation of the ligands at 380 nm, whereas the emission from the mononuclear complex 3 containing ethanol molecules was almost quenched. The emission efficiencies were determined to be 3.1±0.1% for 1 and 3.9±0.1% for 2, respectively. The differential scanning calorimetry (DSC) measurements demonstrated that the decomposition points of 1 and 2 were 309 °C and 320 °C, respectively, indicating high thermostability of these complexes compared to the mononuclear Eu(III) complex 3 (250 °C). New strategy for designing stable rare earth compounds giving strong emission would be emphasized by introducing polynuclear complexes. Polynuclear complexes should open a wide range of molecular design for photosensitized luminescence and thermal stability. 相似文献
6.
A novel europium complex Eu(TTA) 3(CPPO) 2 ( 1) (TTA=thenoyltrifluoroacetone, CPPO=9-[4-(diphenyl-phosphinoyl)-phenyl]-9H-carbazole) based on the phosphine oxide ligand
with bipolar structure was used to fabricate double-layer devices. The strong hole injection and transport ability of 1 was proved. The luminance of 414 cd m −2 was achieved with the device configuration ITO/Eu(TTA) 3(CPPO) 2(40 nm)/BCP (30 nm)/Mg:Ag (BCP = 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline), which is favorable among double-layer
organic light emitting devices based on small molecular Eu 3+ complexes. The maximum current efficiency of 2.44 cd A −1 and external quantum efficiency of 1.55% demonstrate the potential application of 1 as a promising candidate for high-efficiency, simple-structure and pure red-emitting devices. 相似文献
7.
Optical absorption and luminescence spectra of europium doped strontium borate glasses prepared in different conditions are studied. It is found that the percentage of Eu 3+ ions varies from 100 to 30% being controlled by the conditions of preparation. The mechanism, favoring reduction of europium to Eu 2+ state in polycrystalline strontium tetraborate, is much weaker in glasses of the same composition. In samples containing mixed valence europium at densities of 8×10 20 cm −3, the efficient transfer of optical excitation from Eu 3+ to Eu 2+, suppressing the Eu 3+ luminescence, has been found. The most reliable way of monitoring the percentage of europium ions in different valences for strontium borate glasses is the measuring of absorption at f-f transition 7F 0→ 5D 2 of Eu 3+. 相似文献
8.
A multi-functional ligand, 5-acryloxyethoxymethyl-8-hydroxyquinoline (Hamq), was synthesized, which contained a polymerizable C=C double bond for the copolymerization with other vinyl monomers and acted as photon antenna able to transfer energy to Eu 3+ ions effectively. The triplet state energy of Hamq was determined to be 22,370 cm −1 via the phosphorescence spectra of Hamq and its gadolinium complex. The title complex monomer Eu(tta) 2(amq) was prepared by coordination reaction of Hamq with europium isopropoxide and 2-thenoyltrifluoroacetone (Htta) in dry organic solvents under argon atmosphere and characterized by elemental analysis and IR spectrum. The photophysical properties of the complex were studied in detail with UV-vis, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (30.6%) upon ligand excitation and a long 5D 0 lifetime (389 μs), which indicated that the ligand Hamq could sensitize the luminescence of Eu(III) ion efficiently in Eu(tta) 2(amq), resulting in a strong luminescence of its copolymer poly[MMA- co-Eu(TTA) 2(amq)] under UV excitation. The excellent luminescence properties of the complex made it not only a promising light-conversion molecular device but also an excellent luminescent monomer. 相似文献
9.
New kinds of organic-inorganic hybrid materials consisting of lanthanide (Er 3+, Eu 3+, and Tb 3+) complexes covalently bonded to a silica-based network have been obtained by a sol-gel approach. A new versatile compound containing terpyridine has been synthesized by 4′- p-aminophenyl-2,2′:6′,2″-terpyridine and 3-(triethoxysilyl)propyl isocyanate, which is used as the a ligand of lanthanide ions and also the siloxane network precursor. The obtained hybrid materials were characterized by FT-IR, TGA, DSC, near-infrared, and visible spectrofluorometer, as well as decay analysis. For the Hybrid-Er and Hybrid-Eu, excitation at the ligand absorption wavelength resulted in the typical near-IR luminescence (centered at around 1.54 μm) resulting from the 4I 13/2- 4I 15/2 transition of Er 3+ ions and strong visible region emission of the Eu 3+ ions ( 5D 0- 7F J), which contributed to the efficient energy transfer from the ligands to the lanthanide ions. However, we have not found strong emission for the Hybrid-Tb. This indicated that the energy transfer did not take place in this system. A model of indirect excitation mechanism to explain the phenomenon was also suggested. 相似文献
10.
Polycrystalline europium huntite EuAl 3(BO 3) 4 has been prepared by solid-phase synthesis. The spectral and kinetic characteristics of its luminescence under the excitation
by a xenon lamp, single laser pulse, and electron beam have been studied. It has been established that the laser excitation
of the polycrystalline samples in the 7
F
0 → 5
L
6 transition of Eu 3+ ions with the power density P ≥ 5 × 10 7 W/cm 2 leads to the structure rearrangement of the optical centers, which is accompanied by an increase in the probability of the
radiation transitions of the activator. The stimulated radiation of the main type of Eu 3+ centers in the 5
D
0→ 7
F
1, 7
F
2, and 7
F
4 transitions has been obtained under the excitation by the electron beam with an energy of 200 keV and a duration of 2 ns. 相似文献
11.
Lanthanide complexes Ln(bta) 3L 2 (Ln 3+: Eu 3+, Tb 3+ and Ho 3+; bta: benzoyltrifluoroacetonate; L: N-octadecyl-2-hydroxy-4-tetradecyloxybenzal- dimine) are synthesized. Their photoacoustic
(PA) spectra are reported and interpreted. In the region of ligand absorption, PA intensity increases for Eu(bta) 3L 2, Tb(bta) 3L 2 and Ho(bta) 3L 2, respectively. It is found that the PA intensity of the ligand bears a relation to the intramolecular energy transfer process.
By comparison with luminescence spectra, the energy transfer process and phase transition of lanthanide complexes are studied
from two aspects: radiative and nonradiative processes. 相似文献
12.
Eu 2+- and Eu 3+-Zn 2GeO 4 were prepared by the high temperature solid-state reaction method. The phase purity and crystallinity of Zn 2GeO 4:Eu samples were characterized by X-ray diffraction (XRD). The excitation spectra, the emission spectra and the luminescence decay curves of the Eu 2+- and Eu 3+-Zn 2GeO 4 were investigated. Zn 2GeO 4:Eu 2+ gives a bluish-green luminescence with one emission band located at 467 nm, and Zn 2GeO 4:Eu 3+ presents an reddish-orange color due to the transition ( 5D 0→ 7F J, J = 1 and 2) of the Eu 3+ ions. The luminescence decay curves of Eu 2+ and Eu 3+ provide complementary evidence to the mixed valence of europium (Eu 2+, Eu 3+) in Zn 2GeO 4 host. These indicate that the mixed valence of europium (Eu 2+, Eu 3+) coexists in Zn 2GeO 4 host prepared in an oxidizing atmosphere. The abnormal reduction phenomenon of Eu 3+→Eu 2+ in Zn 2GeO 4 host prepared in an oxidizing atmosphere was reported and discussed on the basis of the charge compensation model. 相似文献
13.
Eu 2+-doped BaSi 6N 8O phosphors (Ba 1−xEu xSi 6N 8O, 0.005≤ x≤0.2) were synthesized by gas-pressure sintering of the powder mixture of BaCO 3, Si 3N 4, and Eu 2O 3 at 1750 °C under 0.5 MPa N 2. The fired powder consists of a major BaSi 6N 8O phase and a trace amount of impurity phases. The structural result of the BaSi 6N 8O powder, refined by the Rietveld method, agrees well with that of single crystals. A wide blue luminescence band peaking at about 500 nm is observed in BaSi 6N 8O:Eu 2+, upon excitation with the ultraviolet light of 310 nm. Although Eu is covalently bonded to six nearest neighbor nitrogen atoms, the luminescence of Eu 2+ is not significantly redshifted but shows a very narrow excitation spectrum at high energies. The origin of the short-wavelength luminescence is mainly ascribed to a small crystal-field splitting as a result of extremely long distances between europium and nitrogen ligands in BaSi 6N 8O:Eu 2+. 相似文献
14.
We 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 (-NO 2). 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.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 48–54, January–February, 2007. 相似文献
15.
The luminescence lifetimes of europium(III) complexes with new monophosphorus acid derivatives of H 4dota were measured by means of time-resolved laser-induced luminescence spectroscopy in H 2O and D 2O. The hydration numbers of these complexes were estimated using different empirical equations [Horrocks and Sudnick (1979) J. Am. Chem. Soc. 101 (1979) 334; Choppin and Barthelemy(1989) Inorg. Chem. 28, 3354–3357; Choppin and Bünzli Lanthanide probes in life, chemical and earth sciences. Theory and practice (1989); Kimura and Kato J. Alloys Comp. 275–277 (1998) 806; Parker (1999) J. Chem. Soc., Perkin Trans. 2, 493–503; Supkowski and Horroks (2002) Inorg. Chim. Acta. 340, 44–48]. It was shown that all the relationships gave similar results with a satisfactory precision. The hydration numbers of complexes of H 3do3a and H 4dota agreed with the literature values. One water molecule is coordinated in complexes of the new ligands. The results showed that the Choppin formula based on measurements only in H 2O can be satisfactorily used for estimation of the hydration numbers. 相似文献
16.
In this paper, Eu 3+ β-diketone Complexes with the two ligands 1-(2-naphthoyl)-3, 3, 3-trifluoroacetonate (TFNB) and 2’2-bipyridine (bpy) have
been synthesized. Furthermore, we reported a systematical study of the co-fluorescence effect of Eu(TFNB) 3bpy doped with inert rare earth ions (La 3+, Gd 3+ and Y 3+) and luminescence ion Tb 3+. The co-luminescence effect can be found by studying the luminescence spectra of the doped complexes, which means that the
existence of the other rare earth ions (La 3+, Y 3+, Gd 3+ and Tb 3+) can enhance the luminescence intensity of the central Eu 3+, which may be due to the intramolecular energy transfer between rare earth ions and Eu 3+. The efficient intramolecular energy transfer in all the complexes mainly occurs between the ligand TFNB and the central
Eu 3+. Full characterization and detail studies of luminescence properties of all these synthesized materials were investigated
in relation to co-fluorescence effect between the central Eu 3+ and other inert ions. Further investigation into the luminescence properties of all the complexes show that the characteristic
luminescence of the corresponding Eu 3+ through the intramolecular energy transfers from the ligand to the central Eu 3+. Meantime, the differences in luminescence intensity of the 5D 0→ 7F 2 transition, in the 5D 0 lifetimes and in the 5D 0 luminescence quantum efficiency among all the synthesized materials confirm that the doped complex Eu 0.5Tb 0.5(TFNB) 3bpy exhibits higher 5D 0 luminescence quantum efficiency and longer lifetime than the pure Eu(TFNB) 3bpy complex and other materials. 相似文献
17.
合成了苯甲酸-镝-钇固体配合物并研究了它们的光致发光性质.实验结果表明,当苯甲酸镝中部分Dy3+离子被Y3+离子取代时,可以便配合物中Dy3+离子的发光增强. 相似文献
18.
Uninuclear europium (Eu), as well as binuclear Eu and terbium (Tb), complexes were synthesized using acrylic acid (AA) as the first ligand and 1,10-phenanthroline (Phen) as the second ligand. The relative weight ratio of the europium (III) (Eu 3+) to terbium (III) (Tb 3+) ions of the binuclear complex was 1:1 as determined via energy dispersive X-ray analysis. The structures of the Eu(AA) 3Phen and Eu 0.5Tb 0.5(AA) 3Phen complexes were characterized by Fourier transform infrared spectroscopy. A series of tri-cellulose acetate (TCA)/ the Eu(AA) 3Phen and TCA/Eu 0.5Tb 0.5(AA) 3Phen composites were prepared by solution blending, and their luminescent properties were investigated by fluorescence spectrophotometry. The excitation spectra of all composites indicated that the TCA matrix probably affected the energy absorption and transfer of organic ligands. In TCA/Eu 0.5Tb 0.5(AA) 3Phen composites the introduced Tb 3+ ions had some influence on energy absorption and transfer of organic ligands; the energy transfer process of the complex is suggested to be as follows: Phen→AA→Tb 3+ion→Eu 3+ion. The emission spectra indicated that the luminescent intensity of the TCA/Eu 0.5Tb 0.5(AA) 3Phen composites was noticeably stronger than that of the TCA/Eu(AA) 3Phen composites, suggesting that the comparatively stable and high-efficiency energy transfer process was only slightly influenced by the TCA matrix. In summary, the TCA/Eu 0.5Tb 0.5(AA) 3Phen (90/10) composite possesses fine luminescent properties for potential usage as red fluorescent materials. 相似文献
19.
A β-diketone, 2-acetylfluorene-4,4,4-trifluorobutane-1,3-dione (HAFTFBD), and its three europium(III) complexes, Eu(AFTFBD) 3⋅2H 2O, Eu(AFTFBD) 3(TPPO) 2 and Eu(AFTFBD) 3phen, were designed and synthesized, where TPPO was triphenylphosphine oxide and phen was 1,10-phenanthroline. The complexes
were characterized by IR, UV-visible, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The results
show that the Eu(III) complexes exhibit a high thermal stability,and wide and strong excitation bands when monitored at 613 nm.
Excited by ∼395 nm near UV light, the complexes emitted strong and characteristic red light due to f– f transitions of the central Eu 3+ ion, and no emission from the ligands was found. The photoluminescence mechanism of the europium(III) complexes was investigated
and proposed as a ligand-sensitized luminescence process. Among the three europium(III) complexes, Eu(AFTFBD) 3phen exhibits the highest thermal stability and the most excellent photoluminescence properties. A bright red light-emitting
diode was fabricated by coating the Eu(AFTFBD) 3phen complex onto an ∼395 nm-emitting InGaN chip, and the LED showed appropriate CIE chromaticity coordinates ( x=0.66, y=0.33). A white LED with CIE chromaticity coordinates ( x=0.32, y=0.32) was prepared with Eu(AFTFBD) 3phen as red phosphor, indicating that Eu(AFTFBD) 3phen can be applied as a red component for fabrication of near ultraviolet-based white light-emitting diodes. 相似文献
20.
The reflection and luminescence excitation spectra of CaF 2 crystals containing europium ions in divalent (Eu 2+) and trivalent (Eu 3+) states were measured in the range from 4 to 16 eV. It was established that, in CaF 2 : Eu 3+ crystals, luminescence of Eu 3+ ions (the f- f transitions) is effectively excited both in the charge-transfer band (at ~8 eV) and in the region of the 4 f–5 d transitions (at ~10 eV) but is virtually not excited in the fundamental region of the crystal (at an energy higher than 10.5 eV). Luminescence of Eu 2+ ions (the 427-nm band) in CaF 2 : Eu 3+ is effectively excited in the fundamental region of the crystal; i.e., luminescence of divalent europium ions occurs through the trapping mechanism. Emission of Eu 2+ ions in CaF 2 : Eu 2+ crystals is characterized by the excitation band at an energy of 5.6 eV (the 4 f → 5 d,t 2g transitions), as well as by the exciton and interband luminescence excitations. The results obtained and data available in the literature are used to construct the energy level diagram with the basic electron transitions in the CaF 2 : Eu crystals. 相似文献
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