Europium Β-diketonate Research Articles

Synthesis and luminescent properties of cellulose acetate butyrate films doped with europium complex Eu(TTA)3 for optical thermometry

In this work, the luminescent β-diketonate europium complex, Eu(TTA)3, was incorporated into the polymer cellulose acetate butyrate in different concentrations in the form of composite films. The photoluminescence analysis showed that the composites improved the internal transition of the europium ion, 5D0 → 7F2, mainly responsible for the emission of red light from the complex, by providing a highly asymmetric chemical environment around the europium ion and by reducing non-radiative decays. The composite matrix also contributed to the quantum efficiency of the luminescence, reaching 38 %, by reducing the excited state deactivation rates. The luminescence lifetime of the composite linearly decayed with increasing temperature, while the luminescence intensity displayed an exponential decrease by increasing temperature, both behaviors proved to be appropriate for use in optical thermometry. The analysis of Raman spectra, Judd-Ofelt parameters, decay rates, and lifetime showed that the characteristics of the isolated complex were mostly maintained after being added to the polymeric matrix.

Computational and optoelectronic investigations of red-emissive europium (III) β-diketonate with n-donor ligands for display applications

Europium complexes exhibiting red luminescence were prepared by employing β-diketone as main ligand and 1,10-phenanthroline as an additional ligand. Various methods, including 1H NMR, IR spectroscopy and analysis of optical band gap were employed to examine these complexes. The luminescent photophysical properties were investigated using PL spectroscopy and theoretical calculations were conducted to explore radiative transitions probabilities and Judd-Ofelt (J-O) parameters for transitions of type 5D0 → 7F2, 4. J-O parameters were determined using the JOES computer program and results were in good agreement with the outcomes obtained experimentally. The luminescence analysis results have verified the vibrant, single-color red emission of the prepared complexes. The band gap of ternary europium complexes, determined optically, electronically, and theoretically, falls within the range of 3–4 eV. This similarity indicates that these complexes are potentially suitable as semiconductor materials. The results from absorption, electrochemical and photophysical analyses indicate the potential use of synthesized complexes in lighting and display applications.

Photoluminescence lifetime stability studies of β-diketonate europium complexes based phenanthroline derivatives in poly(methyl methacrylate) films.

In this work, five phenanthroline derivatives substituted with different methyl groups have been selected to synthesize β-diketonate-based europium complexes to check the influence of the substitutions on the degradation effect of those complexes in poly(methyl methacrylate) (PMMA) films. The photophysical properties of Eu(III) complexes, including absorbance, excitation, and emission have been carefully investigated in solution, solid-state, and doped in PMMA film. In all these states, the complexes exhibit an impressive red emission at 614 nm with a high photoluminescence quantum yield of up to 85 %. The films have been exposed under outdoor, indoor, and dark storage stability lifetime conditions for 1200 hours. The photoluminescence measurements recorded every 400, 800, and 1200 hours demonstrated that the film containing europium complex with phenanthroline ligand substituted by a high number of methyl groups (Eu(TTA)3L5) showed good photoluminescent stability in indoor and dark conditions, and exhibited better resistance to degradation in outdoor conditions compared to other complexes. This study has proved that phenanthroline ligands could be tuned chemically leading to better stability of those types of complexes in films which can be end-used for future stable optoelectronic devices such as luminescent solar concentrators.

Оптические свойства триэтиламиниевой соли трифторуксусной кислоты

. Triethylaminium trifluoroacetate (CH3CH2)3NH+ ‒O(O)C‒CF3, obtained by reacting tri-fluoroacetic acid with triethylamine, is a colorless ionic liquid that passes into the vapor phase when heated to 200–220 °C. The compound has been characterized by elemental analysis, infrared spectroscopy, 1H and 13C nuclear magnetic resonance, mass spectroscopy, thermogravimetry, differential scanning calorimetry, refractometry, electron absorption and emission spectroscopy. In the UV spectrum there is a weak absorption band in the range of 260–340 nm. When excited at 320 nm, the compound shows two photoluminescence bands at 375 and 425 nm. The ionic liquid readily dissolves lanthanide coordination compounds: erbium(III) phenanthroline thenoyltrifluoromethyl acetonate Er(tta)3·phen, europium(III) tris(3-trifluoroacetamidobenzoyltrifluoroacetonate) and holmium(III) acetylacetonate Ho(acac)3. The absorption spectra of erbium(III), europium(III), holmium(III) β-diketonates and emission spectra of erbium(III) and europium(III) β-diketonates are presented.

Investigating the long-term stability of photoluminescence lifetimes in PMMA films doped with β-diketonate europium complexes based on bipyridine and terpyridine derivatives

In this work, two β-diketonate ligands: dibenzoylmethane (DBM) and Hexafluoroacetone (hfac) have been selected to synthesize a series of β-diketonate europium complexes based on bipyridine and terpyridine derivatives. These complexes were then incorporated into PMMA films to comprehensively investigate their thermal and long-term photoluminescence stability. Comparatively, Eu(hfac)3L1-5 demonstrated higher heat resistance than Eu(DBM)3L1-5, as indicated by their respective initial decomposition temperatures. Various aspects including absorbance, excitation, and emission were examined in solution, powder, and within the PMMA-doped films. Notably, the complexes exhibited a remarkable red emission peak at 613nm and a high photoluminescence quantum yield. To assess their stability, the films were subjected to light, indoor, and dark storage conditions for 720h, with photoluminescence measurements recorded at both 0h and 720h. The results revealed that the hfac-based europium complexes (Eu(hfac)3L1-5) demonstrated good stability under light, indoor, and dark conditions compared to the DBM-based europium complexes (Eu(DBM)3L1-5). This study highlights the direct impact of the β-diketonate ligand structure on the stability of such complexes in films, thus showcasing their potential for future applications in stable optoelectronic devices.

Green host urethanesil based on castor oil doped with Eu3+ complex

Polymers based on vegetable oils can be suitable candidates for the replacement of fossil polymers, for instance, polyurethanes (PU) based on castor oil. However, the synthesis PU materials are normally carried out using organic solvents, metals, and high temperatures. To overcome these problems, the sol-gel route is an alternative approach based on mild conditions to produce organic-inorganic hybrid urethanesil (Ut) environmentally friendly. Therefore, in this study, we proposed an organic-inorganic hybrid (OIH) synthesis based on castor oil (CO)-derived Ut, as well as the incorporation and interaction of europium β-diketone [Eu(tta)3(H2O)2] in organic-inorganic hybrid matrix. The Ut self-supporting hybrid was synthesized from the reaction of 3-(triethoxysilyl)propyl isocyanate (ICPTES) and CO in a 3:1 M ratio. The films were obtained using the sol-gel process, following the casting method. The CO-based OIH-Ut films showed high transmittance in the visible and infrared spectrum (90%), and urethanesil showed photoluminescence (PL) with emission at 416.0 nm when excited at 319.0 nm. The results also revealed an increase in the intrinsic quantum yield of PL (QLEu) for [Eu(tta)3(H2O)2]. It has been verified a QLEu value of 27% for the isolated complex, whereas when it is incorporated into OIH-Ut a value of 49% was observed.

Impact of chiral ligands on photophysical and electro-optical properties of β-diketonate europium complexes in circularly polarized OLEDs.

Luminescent lanthanide complexes exhibiting chiroptical properties are attracting attention for their application in chiral optoelectronics and photonics, thanks to their unique optical properties, allied to intraconfigurational f-f transitions, which are generally electric-dipole-forbidden and can be magnetic dipole-allowed, which in an appropriate environment can lead to high dissymmetry factors and strong luminescence, in the presence of an antenna ligand. However, because luminescence and chiroptical activity are governed by different selection rules, their successful application in commonly used technologies is still an expectation. Recently, we showed that europium complexes bearing β-diketonates acting as luminescence sensitizers, and chiral bis(oxazolinyl) pyridine derivatives as the chirality inducer, reasonably perform in circularly polarized (CP) organic light-emitting devices (OLEDs). Indeed, europium β-diketonate complexes are an interesting molecular starting point, given their strong luminescence and their established use in conventional (i.e., nonpolarized) OLEDs. In this context, it is interesting to investigate in detail the impact of the ancillary chiral ligand on complex emission properties and the performances of corresponding CP-OLEDs. Here we show that, by incorporating the chiral compound as emitter in the architecture of solution processed electroluminescent devices, CP emission is retained, and the efficiency of the device is comparable to reference unpolarized OLED. The observed remarkable dissymmetry values strengthen the position of chiral lanthanide-OLEDs as CP-emitting devices.

Red-Emitting Latex Nanoparticles by Stepwise Entrapment of β-Diketonate Europium Complexes.

The core-shell structure of poly(St-co-MAA) nanoparticles containing β-diketonate Eu3+ complexes were synthesized by a step-wise process. The β-diketonate Eu3+ complexes of Eu (TFTB)2(MAA)P(Oct)3 [europium (III); 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione = TFTB; trioctylphosphine = (P(Oct)3); methacrylic acid = MAA] were incorporated to poly(St-co-MAA). The poly(St-co-MAA) has highly monodispersed with a size of 300 nm, and surface charges of the poly(St-co-MAA) are near to neutral. The narrow particle size distribution was due to the constant ionic strength of the polymerization medium. The activated carboxylic acid of poly(St-co-MAA) further chelated with europium complex and polymerize between acrylic groups of poly(St-co-MAA) and Eu(TFTB)2(MAA)P(Oct)3. The Em spectra of europium complexes consist of multiple bands of Em at 585, 597, 612 and 650 nm, which are assigned to 5D0→7FJ (J = 0-3) transitions of Eu3+, respectively. The maximum Em peak is at 621 nm, which indicates a strong red Em characteristic associated with the electric dipole 5D0→7F2 transition of Eu3+ complexes. The cell-specific fluorescence of Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA) indicated endocytosis of Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA). There are fewer early apoptotic, late apoptotic and necrotic cells in each sample compared with live cells, regardless of the culture period. Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA) synthesized in this work can be excited in the full UV range with a maximum Em at 619 nm. Moreover, these particles can substitute red luminescent organic dyes for intracellular trafficking and cellular imaging agents.

Thermally Induced Structural Transitions and Temperature Memory Effect in a Luminescent Vitrified Film of an Anisometric Europium(Iii) Β-Diketonate Complex

Thermally Induced Structural Transitions and Temperature Memory Effect in a Luminescent Vitrified Film of an Anisometric Europium(Iii) Β-Diketonate Complex

Synthesis and photophysical properties of ternary β-diketonate europium(III) complexes incorporating bipyridine and its derivatives

Two new octa-coordinated ternary europium(III) complexes of the type [Eu(btfa)3(Br2-bpy)] (Eu-1) and [Eu(btfa)3(PhE2-bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, Br2-bpy = 5,5′-dibromo-2,2′-bipyridine, PhE2-bpy 5,5′-bis(phenylethynyl)-2,2′-bipyridine) together with a previously reported complex [Eu(btfa)3(bpy)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs).

A tris β-diketonate europium(III) complex based OLED fabricated by thermal evaporation method displaying efficient bright red emission

A new tris β-diketonate europium(III) complex [Eu(btfa) 3 Py-Im] ( Eu-1 ) (4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) and 2-(2-pyridyl)benzimidazole (Py-Im)] has been synthesized and structurally characterized. A single crystal X-ray diffraction analysis shows that Eu-1 is octacoordinated and the coordination sphere is composed of a EuO 6 N 2 core with a trigonal dodecahedral (D 2d ) geometry. The photophysical properties of Eu-1 were analysed in detail and with the help of the experimental PL data and theoretical modelling, energy transfer rates were calculated, and an energy transfer mechanism is proposed for Eu-1 . The complex has been used as the emitting layer (EML) to fabricate organic light emitting diodes (OLEDs). Eight OLEDs, of which four single-EML and four double-EML with varying doping concentration, were fabricated via a thermal evaporation method using Eu-1 as the EML. Under the optimum conditions a highly monochromatic bright red emission (CIE x,y = 0.640, 0.311) with brightness (B) = 896 cd/m 2 , current efficiency (η c ) = 2.26 cd/A, power efficiency (η p ) = 1.92 lm/W and external quantum efficiency (EQE) = 1.6% at very low V turn-on = 3.4 V was obtained. • A new [Eu(btfa) 3 Py-Im] has been synthesized and structurally characterized. • Photophysical properties were analysed in detail experimentally and theoretical. • The complex has excellent thermal and photophysical properties. • Pure red emitting OLEDs were fabricated using the complex as an emitter. • Device showed improved EL performance than analogous europium complexes.

Real-Time Tracking of Highly Luminescent Mesoporous Silica Particles Modified with Europium β-Diketone Chelates in Living Cells.

Highly luminescent europium complexes modified mesoporous silica particles (MSP) were synthesized as an imaging probes for both in-vitro diagnostic and in-vivo cellular tracking agents. Europium β-diketone chelates (4,4,4-trifluoro-l-(2-thienyl)-l,3-butanedione) trioctylphosphine europium (III) (Eu(TTA)3(P(Oct)3)3) were incorporated inside the nanocavities that existed in hierarchical MSP (Eu@MSP). The MSP and Eu@MSP on mouse bone marrow-derived macrophages (BMDMs) did not show any toxic effect. The MSP and Eu@MSP in the BMDMs were found at cytoplasm without any degradation and immunogenicity. However, both pro- and anti-inflammatory cytokines of macrophages were significantly increased when lipopolysaccharide and a high concentration (100 μg/mL) of MSP and Eu@MSP were treated simultaneously.

Dependence of the Operational Characteristics of a Luminescent Temperature Probe Based on a Vitrified Film of a Europium(III) β-Diketonate Complex on the Fixing Technology

Dependence of the Operational Characteristics of a Luminescent Temperature Probe Based on a Vitrified Film of a Europium(III) β-Diketonate Complex on the Fixing Technology

In Situ Interactions of Eu(TTA)3(H2O)2 with Latent Fingermark Components-A Time-Gated Visualization of Latent Fingermarks on Paper.

We introduce a new latent fingermark (LFM) development method, where compounds showing long lifetime luminescence are generated in situ by the reactions of Eu(TTA)3(H2O)2 with LFM components. Until now, time-gated imaging could not be used to develop LFM on porous surfaces due to the difficulties with selective binding of the developing agents to the fingermark ridges. The nature of the interactions of Eu(TTA)3(H2O)2 with the LFM material has been investigated for three model compounds commonly found in the LFM composition-oleic acid, l-serine, and squalene. The LFMs developed with the europium β-diketonate complex have been successfully photographed using a time-gated imaging scheme. The presented new approach has been demonstrated to give similar or better results than developing agents commonly used for paper samples (ninhydrin and 1,2-indanedione). Moreover, contrary to the methods mentioned above, the new approach allows for the development of amino acid-poor LFM on paper.

Oxide ancillary ligand-based europium β-diketonate complexes and their enhanced luminosity

Ternary materials of europium complex with 2,2,6,6-tetramethyl-3,5-heptanedione (tmhd) ligand and aqua ligand as ancillary ligands have been prepared and characterized for various optoelectronic characteristics. Reactions of hydrated complex [Eu(tmhd)3(H2O)2] proceeded with triphenylphosphine oxide (TPPO) and pyridine-N-oxide (PNO) ancillary ligands were studied to develop novel complexes. The prepared complexes show good thermal stability. A comparative investigation of prepared materials [Eu(tmhd)3(H2O)2], [Eu(tmhd)3(TPPO)2] and [Eu(tmhd)3(PNO)2] was conducted for their luminescent behaviors in order to obtain the role of ancillary ligand in the enhancement of illumination amount generated from europium (Eu3+) ion. Color coordinates of prepared ternary complexes such as [Eu(tmhd)3(H2O)2] with (x = 0.54, y = 0.32), [Eu(tmhd)3(TPPO)2] with (x = 0.56, y = 0.32) and [Eu(tmhd)3(PNO)2] with (x = 0.57, y = 0.33) indicated that these materials exhibited bright red emission in visible region spectrum. The complexes show a proficient energy transport pathway from the ligands to the innermost Eu3+ by means of an ancillary ligand-sensitized luminescence process. Interaction between the metal and ligand results in a distinguished effect on quantum efficiency (η) as well as on Judd–Ofelt intensity factor (Ω2) of the prepared materials.

Luminescent sensor based on the lanthanide-fibroin composite

Abstract This work aims to produce luminescent sensors based on lanthanide ions and silk fibroin composite films. Associating the physicochemical properties of fibroin with the spectroscopic properties of lanthanide ions can be a strategy to develop a new generation of biocompatible and biodegradable sensors with high transparency in the visible region. The results presented herein are a natural consequence of a previous study that used europium ions as structural probes in the composite fibroin matrix and investigated their potential application as photonic devices. Here, highly transparent thin films containing the silk fibroin matrix and an Eu3+ complex were produced by dip-coating under controlled conditions. Europium thenoyltrifluoroacetonate was employed as the luminescent component of the proposed sensor. The films were characterized by electronic spectroscopy in the UV–Vis region and photoluminescence. The effect of complex insertion on the refraction index of the silk fibroin film was studied. The results showed a high-intensity emission that is characteristic of europium β-diketone chelates, and the intensity of the 5D0 → 7F2 transition depended on the ammonia vapor concentration. To understand the whole process, different composite films were prepared, and the results corroborated the potential use of this system as a photonic sensor of vapors.

A vitrified film of an anisometric europium(iii) β-diketonate complex with a low melting point as a reusable luminescent temperature probe with excellent sensitivity in the range of 270–370 K

Vitrified film of europium(iii) β-diketonate complex as reusable highly sensitive luminescent temperature probe suitable for long-term monitoring in range of 270–370 K.

Novel trivalent europium β-diketonate complexes with N-(pyridine-2-yl)amides and N-(pyrimidine-2-yl)amides as ancillary ligands: Photophysical properties and theoretical structural modeling

Eighteen new Eu3+ complexes and their Gd3+ analogues with 1,3-diketonate as main ligands and N-(pyridine-2-yl)amides or N-(pyrimidine-2-yl)amides as ancillary ligands were synthesized. The replacement of water molecules by those amides in the Eu3+ complexes increase the intrinsic quantum yields of luminescence, making them comparable or even more efficient than Eu3+ complexes with standard ancillary ligands such as 2,2′-bipyridine. The luminescence spectra of Gd3+ complexes in comparison with the Eu3+ ones show that efficient ligand-to-metal intramolecular energy transfer processes take place. In most cases the experimental Judd-Ofelt intensity parameters (Ω2 and Ω4) for the Eu3+ complexes show variations as a function of the temperature (77 and 300 K) that overall apparently does not follow clearly any trend. For this reason, geometric variations (on the azimuthal angle φ and ancillary ligands distances) were carried out in the coordination polyhedron for simulating thermally induced structural changes. It has been observed that, in this way, the Ω2 and Ω4 can be satisfactorily reproduced by in silico experiments. It was concluded that, at low-temperature, the ancillary ligands become closer to the Eu3+ ion and the angular variations affect more Ω2 than Ω4, in agreement to the theoretical calculations. The use of N-(pyridine-2-yl)amides or N-(pyrimidine-2-yl)amides as ancillary ligands in Eu3+ 1,3-diketonates looks to be a good strategy for obtaining highly luminescent complexes.

Luminescent Vesicles and Lyotropic Liquid Crystals in Ethylammonium Nitrate from a Partially Amphiphilic Eu Complex.

Soft luminescent materials have attracted much attention because of their self-assembled and controllable properties. To explore their facile and effective fabrication ways, we report here the self-assembling of luminescent vesicles and lyotropic liquid crystals (LLCs) in a protic ionic liquid, ethylammonium nitrate, by a partially amphiphilic europium β-diketonate complex (Eu(III)) with a 1-dodecyl-3-methylimidazolium cation as the counter ion. An interesting result came from the complex-induced vesicle formation of corresponding amphiphile, 1-dodecyl-3-methylimidazolium bromide ([C12mim]Br), which has been rarely reported in the past. It was the interaction between the Eu(III) and imidazolium group that changed the critical packing parameter of [C12mim]Br, which finally resulted in the occurrence of vesicles. The obtained vesicle aggregates exhibited enhanced fluorescence intensity and lifetime compared to those of Eu(III) solution. Meanwhile, a hexagonal LLC phase with better fluorescence properties was found at higher [C12mim]Br concentration. The obtained photophysical data confirmed that the order degree of Eu(III)-containing aggregates could effectively increase the energy transition efficiency of ligands. The better luminescent properties of LLC resulted from the stronger stabilizing and binding effects on Eu(III) in LLC than that in vesicles, which might be caused by closer molecular packing in LLC. The results presented here will not only expand the strategy of constructing lanthanide-containing luminescent soft materials in ionic liquids but also provide reference to better understand the effect of organized aggregates on luminescence properties.

Temperature-sensitive luminescent photopolymer activated by europium β-diketonate complexes

Photopolymer luminescent compositions containing chelate complexes of Eu3 + with 2-naphthoyltrifluoroacetone and trioctylphosphine oxide as a luminescent dopant have been developed for the photopolymer-based 3-D printing techniques. Photocured samples of photopolymer compositions are transparent in the visible range and have bright red luminescence under the UV excitation. Photophysical studies have revealed that photocured samples possess high quantum yields of luminescence up to 0.59 and monoexponential luminescence decay with 640 μs lifetime at 293 K. It was found that the luminescence of photocured samples is temperature-dependent; the luminescence lifetime of Eu3 + ions decreases threefold during the heating from 293 to 373 K. The combination of monoexponential luminescence decay and high quantum yield is very promising for printing of temperature sensors.