Fluorescence Intensity Of Eu3 Research Articles

Eu3+-Doped aluminum Metal-Organic Frameworks: A versatile platform for ratiometric detection of histidine and Water, and visible fingerprint identification

Ratiometric fluorescent sensors possess inherent self-calibration features that enable the mitigation of interference from factors unrelated to the analysis. This characteristic results in heightened sensitivity and more pronounced visual detection during qualitative and quantitative analytical processes. A ratiometric fluorescence probe Eu/Al-MOF has been successfully prepared via Eu3+ doped aluminum metal − organic frameworks. Upon introducing histidine, the fluorescence intensity of Eu3+ showed a noteworthy increase, whereas the intensity originating from the ligand decreased owing to enhancing energy transfer from the ligand to Eu3+ ions in the probe. Eu/Al-MOF could detect histidine over a wider linear range of 0.1–400 μM and a lower detection limit of 0.04 μM. Besides, in the presence of water in organic solvents, the excited state of Eu3+ in the probe could be coupled with the O-H oscillation of water molecules, and the excited state energy from Eu3+ would be transferred to the water molecules so that only the fluorescence intensity of Eu3+ gradually decreased. Thus, the proportional detection of trace water could be realized. In ethanol and DMF, the detection range for water was 0.1–20 % and 0.5–20 %, respectively. Moreover, it was found that Eu/Al-MOF could efficiently achieve the visualization identification of fingerprints, providing the possibilities for applying the nano-sensor as a promising multifunctional fluorescence probe.

Sensitive and smartphone-assisted visual detection of oxytetracycline by a ratiometric fluorescence sensor based on nitrogen-doped carbon quantum dots from banana peel cooperating with europium

Oxytetracycline (OTC) residues have serious adverse effects on human health. Thus, selective and sensitive field detection methods are needed. Here, we successfully synthesized nitrogen-doped carbon quantum dots (N-CQDs) with good water-solubility, prominent fluorescence (FL), and favorable stability via a one-step hydrothermal method using banana peel as a carbon source and diethylenetriamine as a nitrogen source. We used the N-CQDs to create a ratiometric FL probe by self-assembling them with europium ions (Eu3+), enabling OTC detection. The FL intensity of N-CQDs at 445 nm was quenched due to the inner filter effect, while the FL intensity of Eu3+ at 621 nm markedly increased via the antenna effect upon OTC introduction. The ratiometric FL sensor demonstrated two linear relationships with OTC concentrations, ranging from 0.01 to 5 μg mL−1 and 5 to 25 μg mL−1, with a limit-of-detection of 4.9 ng mL−1 for OTC. Additionally, this platform depicted an apparent color change from blue to purple under a 365 nm ultraviolet–visible lamp, and a visual semi-quantitative analysis of OTC was achieved using a mobile phone application. We successfully implemented this method to detect OTC in pork muscle and swine urine, achieving remarkable recovery results (96.89–103.20%). Therefore, our findings demonstrate the potential of this approach for real-time and semi-quantitative OTC detection.

Europium(III)-Based Fluorescent Microspheres with Styrene Copolymerization toward an Enhanced Photoluminescence Performance

Rare earth-based polystyrene (PS) fluorescent microspheres, which vigorously combine the merits of rare earth elements and polystyrene microspheres, hold great potential for applications in the state-of-the-art technology and tremendous efforts have been devoted to the photoluminescence field. Herein, a 5-acrylamido-1,10-phenanthroline (Aphen) and Eu(III)-based polystyrene fluorescent microsphere was developed via a facial copolymerization strategy. The optimal complexes of Eu(β-NTA)3(Aphen) and Eu(BFA)3(TPPO)2 were fabricated as the luminescent materials. Specifically, Eu(β-NTA)3(Aphen)-PS was modified for the first time to enhance the photoluminescence property, which effectively integrated the Aphen with styrene monomer. Meanwhile, Eu(BFA)3(TPPO)2 was encapsulated into PS microspheres for the realization of Eu(BFA)3(TPPO)2-PS via an ubiquitous embedding process. The fluorescent intensity of Eu(β-NTA)3(Aphen)-PS was notably reinforced along with an increasing concentration of the rare earth complexes. However, the fluorescence intensity of Eu(BFA)3(TPPO)2-PS was decreased when the concentration was 50 mg due to the saturated solubility of the complexes. The obtained copolymerization fluorescent microspheres could prevent the premature leakage of the fluorescent complexes in a natural environment and showed an outstanding photoluminescence efficiency.

A red-emitting Europium(III) complex as a luminescent probe with large Stokes shift for the sequential determination of Cu2+ and biothiols in real samples

In this work, a novel Eu3+-DTPA-bis(AMC) complex with red luminescence was designed and synthesized for sequential detection of Cu2+ and biothiols (Cys/Hcy/GSH) based on the displacement strategy with the good selectivity, high sensitivity, and large Stokes shift (288 nm). The possible detection mechanism was verified by UV–vis, the high-resolution mass spectrometry, and the fluorescence decay curve. The experimental parameters, including the solution pH, the incubation time, the concentration ratio of Eu3+-DTPA-bis(AMC) to Cu2+ and biothiols concentration, were optimized. Under the optimal conditions, it shows a good linear relationship between the concentration (0–10 μM) of Cu2+ and the fluorescence intensity of Eu3+-DTPA-bis(AMC), with a low detection limit of 0.065 μM. The linear range and the limit of detection of the Eu3+-DTPA-bis(AMC)/Cu2+ system for Cys/Hcy/GSH were 2.5–22.5/5–45/5–50 μM and 0.11/0.07/0.05 μM, respectively. Surprisingly, the high or low concentration of Eu3+-DTPA-bis(AMC)/Cu2+ can significantly affect the selectivity of the sensing system to biothiols (Cys/GSH/Hcy). When the concentration of the Eu3+-DTPA-bis(AMC)/Cu2+ system is 10.0 μΜ, it could recognize biothiols (Cys/GSH/Hcy) from other substances, but when the concentration is as low as 3.3 μM, it could further specifically distinguished Cys from Hcy/GSH. Owing to the high anti-interference characteristics, accuracy and specificity, the sensing system was well applied to the cascade detection of Cu2+ in actual environmental samples and Cys in biological and food samples, including FBS, urine, milk, beverage, fresh juice with the satisfactory recoveries from 96.20 to 106.80 %.

Synthesis, fluorescence properties and F− detection performance of Eu(III) complexes based on the novel coumarin Schiff base derivatives

Three novel coumarin Schiff base derivatives and corresponding Eu(III) complexes were designed and synthesized. The aggregation-induced emission (AIE) property of ligands was studied. The fluorescence properties and electrochemical properties of Eu(III) complexes were investigated by comparing different substituent groups. The ion selectivity and ion detection limits of the [EuL2(NO3)3] •H2O were also studied. The result indicates that all ligands exhibit the AIE property in CH3CN/H2O solution and emit green fluorescence with the maximum emission wavelength of 552 nm. All complexes show characteristic red fluorescence of Eu(III) and the influence of different substituents on the fluorescence intensity of Eu(III) complexes is ordered: -OCH3 > -H > -NO2, and [EuL2(NO3)3] •H2O exhibits the strongest fluorescence intensity. The density functional theory (DFT) calculations of the ligands indicate that the introduction of electron-donating groups increases the HOMO energy level and the electron cloud density, which enhance the ability to coordinate with Eu(III) and the fluorescence intensity of the corresponding complex. Besides, the electrochemical properties of Eu(III) complexes indicate that the introduction of electron-donating groups increases the energy gaps (Eg) and the conjugation of the complex, which enhances the fluorescence intensity of the complexes. Ion selectivity experiments show that [EuL2(NO3)3] •H2O has a specific recognition function for F−, and its response limit is between 1.0 × 10−5 mol·L−1 and 2.2 × 10−5 mol·L−1. Based on the above results, all the ligands and Eu(III) complexes have a promising application in optical materials due to the excellent fluorescence properties. In addition, All Eu(III) complexes also have a potential application prospects in the field of fluoride ion detection.

Electronic synergy between ligands of luminol and isophthalic acid for fluorescence ratiometric detection of Hg2+

Stimulus-responsive double-ligand luminol-Eu-IPA infinite coordination polymer nanoparticles (luminol-Eu-IPA CPNPs) were prepared as a ratiometric fluorescence probe for highly selective detecting Hg2+. The CPNPs were constituted of Eu3+ as the nuclear metal coordinated by isophthalic acid (IPA) together with luminol as an auxiliary ligand. The photoinduced electron transfer (PET) occurring from IPA to luminol prevented the antenna effect between IPA and Eu3+, leading to the quench fluorescence of Eu3+ under light excitation. As Hg2+ has a high affinity to N atom of luminol and the spin-orbit coupling effect, spectroscopically and magnetically silent properties, the fluorescence intensity of luminol was quenched. Meanwhile, the PET effect between luminol and IPA was interrupted under the presence of Hg2+. This process resulted in a significant decrease in the fluorescence intensity of luminol and a significant increase in the fluorescence intensity of Eu3+. Therefore, the fluorescence ratiometric detection of Hg2+ was performed by monitoring the ratio of the fluorescence at 617 nm of Eu3+ to that at 430 nm of luminol. The linear range was from 0.05 to 20 μM with a detection limit as low as 13.2 nM Hg2+ (S/N = 3). Due to the fluorescence of luminol be quenched and the effect of PET be disrupted simultaneously, the probe exhibiting excellent detection selectively can avoid false positive signals, which was demonstrated for monitoring mercury ions in real water samples. Precision in positioning ligands in CPNPs is an advantage to achieve high specificity in comparison to traditional organic dendrimers or precious metal nanomaterials.

Preparation and fluorescence properties of novel 2-quinolone derivatives and their corresponding Eu(III) complexes

A series of novel 2-quinolone ligands and their corresponding Eu(III) complexes were prepared. The effect of different solvents, different ligand concentrations and different substituents on the fluorescence intensity of ligands were investigated in detail. The fluorescence intensity of Eu(III) complexes were studied by comparing different substituents on the ligand. The results indicate that all ligands show the strongest fluorescence intensity in ethanol with the ligand concentration of 50 μM. Among these ligands, the ligand (K6) containing -COOCH3 group owns the strongest fluorescence intensity and the corresponding fluorescence quantum yield reaches 0.317. All complexes exhibit characteristic red light of Eu(III) ions with good thermal stability. The effect of diverse substituents on the fluorescence intensity is ordered: -COOCH3>-Cl> -Br> -OCH3>-CH3>-H, which indicates the complex [EuK6(NO3)3]·2H2O with the strongest electron-donating group (-COOCH3) possesses the strongest fluorescence intensity. The above analysis shows that the ligand (K6) and corresponding Eu(III) complex [EuK6(NO3)3]·2H2O own the best fluorescence property, which has an outstanding application prospect in the field of optical materials and biomedicine materials.

Recyclable Eu3+ functionalized Hf-MOF fluorescent probe for urinary metabolites of some organophosphorus pesticides

A luminescent metal-organic framework Eu3+ functionalized Hf-MOF (Eu3+@1) is designed through post-synthesis modification (PSM) and utilized as a probe for detecting p-nitrophenol (PNP, the urinary metabolite of parathion, methyl-parathion and EPN) and 3-methyl-4-nitrophenol (PNMC, the urinary metabolite of fenitrothion). The apparent quenching effect in urine is observed from the Eu3+@1 with the addition of organophosphorus metabolites. The fluorescent probe has several appealing merits, such as high selectivity, excellent sensitivity (0.36 μg mL−1 for PNP, 0.41 μg mL−1 for PNMC), fast response time (less than 1 min) and easy preparation. Linear correlation between the fluorescence intensity of Eu3+@1 and the concentration of PNP and PNMC are from 0.005 to 0.15 mg mL−1 and 0.005–0.30 mg mL−1, respectively. Furthermore, this fluorescent material also demonstrated the possibility for recycling. It is a prominent candidate for potential application in personalized monitoring the internal dose of human exposure to some organophosphorus pesticides.

Synthesis and luminescent properties of novel red-emitting Eu(III) complexes based on alanine aliphatic derivatives with different optical rotation

A series of novel luminescent amino acid-rare earth complexes (denoted as Eu(L/D-SA)3-Phen) have been successfully synthesized. Using stearoyl alanine (denoted as SA) with different optical rotations as the first ligand and 1,10-phenanthroline (Phen) as the second ligand, the products were prepared by solution chemical reaction. Fourier transform infrared spectrometer (FT-IR), nuclear magnetic resonance spectroscopy (1H NMR), x-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet and visible spectrum (UV) and photoluminescence spectroscopy were used to characterize the properties of Eu(L/D-SA)3-Phen. FT-IR, 1H NMR and XRD indicate that ligand SA and Phen were prepared and successfully combined with Eu3+ ions. SEM analysis shows relatively uniform morphological structure. Eu(L/D-SA)3-Phen exhibit a typical luminescence emission peak at 614 nm. In addition, the lifetimes of Eu(L/D-SA)3-Phen are in scale of millisecond. The relationship between fluorescence intensity of Eu(L/D-SA)3-Phen and the optical rotation of ligand SA has been studied and discussed. Based on the results, Eu(L/D-SA)3-Phen have excellent luminescent performance and possess potential application as luminescent materials.

Structure, thermal and luminescence properties of Eu/Tb(BA)3phen/PAN fibers fabricated by electrospinning

Novel high luminescence fibers often exhibit potential applications in the fields of color displays and sensor systems. In this study, Eu(BA)3phen and Tb(BA)3phen powders was successfully synthesized by solvothermal reactions, firstly. Then, three kinds of novel flexible Eu(BA)3phen/PAN, Tb(BA)3phen/PAN and Eu/Tb(BA)3phen/PAN (BA = benzoic acid, phen = phenanthroline, PAN = Polyacrylonitrile) fibers had been successfully prepared by electrospinning technology. The characterizations of the final products have been investigated in detail. It was found that the diameter of the as-prepared fibers were almost uniform with the fabricated complexes doping into PAN successfully. Thermogravimetric analysis indicates that the thermal stability of the pure PAN fiber could be improved by the incorporation of the complex, although only 1 wt % was added. Furthermore, in Eu/Tb(BA)3phen complex, the fluorescence intensity of Eu3+ ions was remarkably increased by adding Tb3+ ions. This is primarily due to an energy transfer from the 5D4 level of Tb (III) to the 5D0 level of Eu (III) ions, where Tb3+ acted as sensitizer. The corresponding luminescent fibers displayed the same regularity as the complexes. Moreover, with the increasing of the incorporation of complexes into PAN, the fluorescence intensities were significantly enhanced and reached its maximum value at 2.5 wt % for Eu(BA)3phen/PAN fibers and 2.0 wt% for Tb(BA)3phen/PAN fibers. The further intensity decreased with the increasing content of the complexes because of typical emission concentration quenching.

Preparation, characterization and application of EVA film containing Eu3+ complex with 1-tridecanecarboxylic acid ligand

In this study, on the basis of complex Eu(DBM)3Phen which was widely applied in polymer matrices, quaternary complex Eu(DBM)2Phen(TA) was synthesized by the introduction of 1-tridecanecarboxylic acid (TA). XRD analyses show that Eu(DBM)2Phen(TA) inclines to amorphization compared with Eu(DBM)3Phen which is crystal. Ethylene-vinyl acetate (EVA) film doped with Eu(DBM)2Phen(TA) was prepared by casting method. SEM and AFM analyses show that the compatibility of Eu(DBM)2Phen(TA) with EVA is better than that of Eu(DBM)3Phen with EVA. Under the same addition amount of Eu3+ complexes, visible light transmittance of Eu(DBM)2Phen(TA)/EVA film is obviously greater than that of Eu(DBM)3Phen/EVA film, and the fluorescence intensity of Eu(DBM)2Phen(TA)/EVA film is only slightly lower than that of Eu(DBM)3Phen/EVA film. With the optimum addition amount of Eu3+ complexes, the energy conversion efficiency of the polycrystalline silicon solar cell coated with Eu(DBM)2Phen(TA)/EVA film is improved to 12.14%, and in comparison, that of the solar cell coated with Eu(DBM)3Phen/EVA film is only 11.98%. Hence Eu(DBM)2Phen(TA)/EVA film has a potential prospect as luminescent down-shifting material.

Flexible composite nanobelts: facile electrospinning construction, structure and color-tunable photoluminescence

The flexible color-tunable [Eu(BA)3phen + Tb(BA)3phen]/PMMA composite nanobelts have been fabricated by single axial electrospinning. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and fluorescence spectroscopy were used to characterize the final products. As-prepared nanobelts are almost uniform and the thickness and width of them are respectively ca. 890 nm and 16.6 ± 0.09 μm. The fluorescence intensity of Eu3+ is increased with adding more Eu(BA)3phen into the composite nanobelts, and the fluorescence intensity of Tb3+ is found to increase monotonically with introducing more Tb(BA)3phen into the composite nanobelts. By adjusting the ratio of Eu(BA)3phen to Tb(BA)3phen complexes, the fluorescence color of composite nanobelts can be tuned from red to yellow, yellow green, and green under the excitation of 290-nm single-wavelength ultraviolet light. Besides, the emission color could also be tuned easily from red to yellow, yellow to green via variation of excitation wavelengths. The novel color-tunable composite nanobelts have potential applications in the fields of color displays and sensor systems.

Repeatable fluorescence switcher of Eu3+-doped CeO2nanorods byl(+)-ascorbic acid and hydrogen peroxide

Inorganic phosphors of Eu3+-doped CeO2 nanorods were synthesized by a hydrothermal method, followed by high temperature calcination. The phosphors with various doping concentrations of Eu3+ exhibited similar rod-like morphology. These phosphors with different Eu3+ contents can be effectively excited at 340 nm due to the charge transfer from O2− to Ce4+, and display orange and red emissions of Eu3+. It was found that the fluorescence intensity of Eu3+-doped CeO2 nanorods was exponentially decreased with increase in the concentrations of L(+)-ascorbic acid, resulting from the chemical reduction of Ce4+ into Ce3+ and the subsequent excitation cut-off of O2− to Ce4+. The fluorescence intensity of reduced phosphors was restored to the original intensity reversibly by adding hydrogen peroxide, which oxidized Ce3+ into Ce4+. The evolution in fluorescence intensity was consistent with surface Ce3+ fractions of Eu3+-doped CeO2 nanorods, which were 22.0% for as-synthesized phosphors, 34.6% for reduced phosphors and 23.2% for restorative phosphors oxidized by H2O2, respectively. The quantitative and repetitive fluorescence switching of Eu3+-doped CeO2 nanorods by adding L(+)-ascorbic acid and hydrogen peroxide alternatively indicates their potential applications as fluorescence switching devices and chemical or biological sensors for detection and monitoring.

Synthesis and Characterization of Heteronuclear Copper(II)-Lanthanide(III) Complexes of N,N′-1,3-Propylenebis(Salicylaldiminato) Where Lanthanide(III) = Gd or Eu

Three complexes, namely, [Cu(salbn)] (1), [Cu(salbn)Gd(NO3)3·H2O] (2), and [Cu(salbn)Eu(NO3)3·H2O] (3) where salbn = N,N′-1,3-propylenebis (salicylaldiminato) have been synthesized and characterized by elemental analyses, ICP-AES, IR, UV, NMR, MS, EDX, powder XRD, and EPR spectroscopies. The EDX results suggest the presence of two different metal ions in heteronuclear complexes (2) and (3). The ligand(salbn), complex (1), and complex (3) crystallize in triclinic system while complex (2) crystallizes in monoclinic system. The EPR studies suggest that [Cu(salbn)] complex is tetragonally coordinated monomeric copper(II) complex with unpaired electron in the dx2-y2 orbital and spectral features that are the characteristics of axial symmetry while complex (2) in DMF solution at liquid nitrogen temperature exhibits an anisotropic broad signal around g ~ 2.03 which may suggest a weak magnetic spin-exchange interaction between Gd(III) and Cu(II) ions. The fluorescence intensity of Eu(III) decreased markedly in the complex (3).

PHOTONIC BAND GAP EFFECT ON ENERGY TRANSFER IN Tb3+, Eu3+ CO-DOPED TiO2 INVERSE OPAL FILMS

The energy transfer from Tb 3+ to Eu 3+ co-doped TiO 2( TiO 2: Tb , Eu ) inverse opal photonic crystals was investigated by photoluminescence. The results showed that the photonic band gap enhanced energy transfer from the donor Tb 3+ to the acceptor Eu 3+. When the fluorescence emission wavelength of Tb 3+ overlaps with the photonic band gap, the fluorescence intensity of Tb 3+ is suppressed, while the fluorescence intensity of Eu 3+ is enhanced. Energy transfer efficiencies were attributed to the tuning effects of energy transfer in the photoluminescence process by photonic crystal structure.

Synthesis of Novel Eu(III) Luminescent Probe Based on 9- Acridinecarboxylic Acid Skelton for Sensing of ds-DNA

Eu(III)-9-acridinecarboxylate (9-ACA) complex was synthesized and characterized by elemental analysis, conductivity measurement, IR spectroscopy, thermal analysis, mass spectroscopy, (1)H-NMR, fluorescence and ultraviolet spectra. The results indicated that the composition of this complex is [Eu(III)-(9-ACA)(2)(NCS)(C(2)H(5)OH)(2)] 2.5 H(2)O and the oxygen of the carbonyl group coordinated to Eu(III). The interaction between the complex with nucleotides guanosine 5'- monophosphate (5'-GMP), adenosine 5'-diphosphates (5'-ADP), inosine (5'-IMP) and CT-DNA was studied by fluorescence spectroscopy. The fluorescence intensity of Eu(III)-9-acridinecarboxylate complex was enhanced with the addition of CT-DNA. The effect of pH values on the fluorescence intensity of Eu(III) complex was investigated. Under experimental conditions, the linear range was 9-50 ng mL(-1) for calf thymus DNA (CT- DNA) and the corresponding detection limit was 5 ng mL(-1). The results showed that Eu(III)-(9-ACA)(2) complex binds to CT-DNA with stability constant of 2.41 × 10(4) M.

New Luminescent Bioprobes Eu(lll)-phloroglucinol Derivatives and Their Spectrofluorimetric, Electrochemical Interactions with Nucleotides and DNA

Two new ligands derived from phloroglucinol 2-{[(4-methoxy benzoyl)oxy]} methyl benzoic acid[L1] and 2-{[(4-methyl benzoyl)oxy] methyl} benzoic acid[L2] were synthesized. The solid complex Eu(III)-L2 has been synthesised and characterized by elemental analysis, UV and IR spectra. The reaction of Eu(III) with the two synthesized ligands has been investigated in I = 0.1 mol dm(-3) p-toluene sulfonate by cyclic voltammetry and square wave voltammetry. The reaction of Eu (III)-L1 and Eu (III)-L2 binary complexes with nucleotide 5'-AMP, 5'-ADP, 5'-ATP, 5'- GMP, 5'-IMP, and 5'-CMP has been investigated using UV, fluorescence and electrochemical methods. The experimental conditions were selected such that self-association of the nucleotides and their complexes was negligibly small, that is, the monomeric complexes were studied. The interaction of the Eu(III)-L1 or L2 solid complexes with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery(CV), differential pulse polarography (DPP) and square wave voltammetry (SWV) on a glassy carbon electrode. The fluorescence intensity of Eu(III)-L2 complex was enhanced with the addition of DNA. Under optimal conditions in phosphate buffer pH 7.0 at 25 °C the linear range is 3-20 μM for calf thymus DNA (CT-DNA) and the corresponding determination limit is 1.8 μM.

Energy Transfer Enhancement in Eu3+, Tb3+‐Doped SiO2 Inverse Opal Photonic Crystals

The energy transfer from Tb3+ to Eu3+‐doped SiO2 (SiO2:Eu3+, Tb3+) inverse opal photonic crystals was investigated by photoluminescence and fluorescence lifetime. The results showed that the photonic band gap enhanced energy transfer from the donor Tb3+ to the acceptor Eu3+. When the fluorescence emission wavelength of Tb3+ overlaps the photonic band gap, the fluorescence intensity of Tb3+ is suppressed, and the fluorescence intensity of Eu3+ is increased because of the enhancement of energy transfer. In addition, the fluorescence lifetime of Tb3+ decreased.

Efficient fluorescence emission and photon conversion of LaOF:Eu3+ nanocrystals

Efficient spectral conversion of 325–550 nm light to 570–710 nm light has been demonstrated in LaOF:Eu3+ nanocrystals. When levels above the D50 level of Eu3+ are optically excited, strong emission arising from the D50 level is obtained in the range of 570–710 nm, a highly efficient working range for organic solar cells. The influences of ambient temperature, particle size, dopant concentration, and codoped ions on the fluorescence intensity of Eu3+ are discussed in detail. The photon conversion efficiency can reach 3.91% in LaOF:Eu3+ codoped with Tm3+, if light reflection and scattering effects are ignored

Structural, Thermal, and Fluorescence Properties of Eu(DBM)3Phenx Complex Doped in PMMA

Tris (dibenzoylmethanido) (o-phenanthroline)-europium(III) complexes [Eu(DBM)(3)(Phen)(x)] have been synthesized, and their structural, thermal, and fluorescence properties have been investigated both as an independent complex and also after embedding it in poly(methyl methacrylate) (PMMA) polymer matrix. X-ray analysis reveals an unusual crystalline to amorphous transformation in structure of the Eu(DBM)(3)Phen(x) complexes when x exceeds 1.0 (mole %). Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) analysis depict the interaction between the Eu(DBM)(3)Phen(x) complex and the PMMA matrix. The fluorescence intensity of Eu(3+) ion in the Eu(DBM)(3)Phen(1·5) complex is an order of magnitude larger compared to the Eu(DBM)(3)·2H(2)O complex. In addition to the transition (5)D(0) → (7)F(2,) which has a rise time of 83 μs, transitions from the (5)D(1) and (5)D(2) levels are also observed, along with several ligand field splittings in the Eu(DBM)(3)Phen(1·5) complex. Appearance of a rise time (∼0.76 ns) in the decay of the fluorescence from DBM in the presence of Phen and a simultaneous large decrease in the fluorescence intensity (both the singlet and triplet emission) of DBM along with a decrease in fluorescence decay time, in the presence of Eu(3+), indicates a cascading excitation energy transfer from Phen to DBM and finally to the (5)D(0) state of Eu(3+) ion in Eu(DBM)(3)Phen(1.5) through short-range excitation energy transfer. A systematic and significant improvement in the thermal and fluorescence properties of the complex is observed with an increase in the mole concentration of Phen. The maximum fluorescence is observed for Eu(DBM)(3)Phen(1·5), which is a new composition as compared with the usual composition reported earlier. This finding indicates the possibility for the development of brighter luminescent lanthanide photonic materials.