Hu Shui

Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

Abstract Two kinds of Eu-complexes, Eu(TTA)2(Phen)(AA) and Eu(TTA)2(Phen)(MA) (HTTA=2-Thenoyltrifluoroacetone, Phen=1,10- phenanthroline, AA=acrylic acid, MA=Maleic anhydride), which combined the excellent fluorescence properties of Eu(TTA)2(Phen)(H2O) and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared (IR) spectra, and X-ray photoelectron spectroscopy (XPS). Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the Ωλ (λ=2 and 4) experimental intensity parameters were calculated. The results demonstrated that the Ω2 intensity parameters for the two complexes were smaller than those for the Eu(TTA)2(Phen)(H2O) complex, indicating that a less symmetrical chemical environment existed in the complexes. It implied that the radiative efficiency of the 5D0 of these two complexes could be enhanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA (τ=7.26×10−4 s) or Eu-MA complex (τ=8.12×10−4 s) was higher than that of the Eu(TTA)2(Phen)(H2O) complex, which was attributed to the substitution of the water molecule (H2O) in Eu(TTA)2(Phen)(H2O) by the MA or AA ligand.

Electrospinning preparation and luminescence properties of Eu(TTA)3phen/polystyrene composite nanofibers

Abstract Efficient luminescent composite nanofibers, composed of polystyrene (PS, M w =250000) and europium complex Eu(TTA) 3 phen (TTA=2-thenoyltrifluoroacetone, phen=1,10-phenanthroline) with diameters ranging from 350 nm to 700 nm, were prepared by electrospinning and characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), fluorescence spectroscopy, and thermogravimetric analysis (TG). The room-temperature fluorescence spectra of the composite nanofibers were composed of the typical Eu 3+ ion red emission, assigned to the transitions between the first excited state ( 5 D 0 ) and the multiplet ( 7 F 0–4 ). Owing to the incorporation of the europium complex into the PS fiber matrix and the subsequent distortion of the symmetry around the lanthanide ions by the capping PS, the polarization of the Eu 3+ ions was enhanced, which increased the probability for electronic dipole allowed transitions. The monochromaticity ( 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 ) around the Eu 3+ ions was also efficiently improved. Judd-Ofelt intensity parameters (Ω 2 and Ω 4 ) were determined from the emission spectra based on the 5 D 0 → 7 F 2 and 5 D 0 → 7 F 4 electronic transitions, respectively. The results showed that the Ω 2 values of the composite nanofibers were apparently higher than that of the pure complex, indicating an increased covalency degree in the europium first coordination shell due to the modification of PS matrix. The modification of the polymer matrix also resulted in much higher thermal stability of the composite fibers than that of the pure complex.

Physical dispersion state and fluorescent property of Eu-complex in the Eu-complex/silicon rubber composites

Abstract The fluorescent complex Eu(TTA) 2 (Phen)(MA) (HTTA=2-Thenoyltrifluoroacetone, Phen=1,10-phenanthroline, MA=Maleic anhydrider) was synthesized and characterized with elemental analysis, infrared spectrum (IR), scanning electron microscope (SEM), X-ray Diffraction(XRD), differential scanning calorimetry(DSC), and fluorescent measurement. To explore the effect of different physical dispersion state of Eu-complex on the fluorescent property of the Eu-complex/silicon rubber composites, various quantities of Eu(TTA) 2 (phen) (MA) were mixed with silicon rubber (SiR) and peroxide to form uncured composites. These composites were vulcanized to obtain cured Eu-complex/SiR composites at 250 °C, which was higher than the melting-point of Eu-complex. The SEM, XRD, DSC, and the fluorescent measurement of these composites showed that both the complex molecules dispersed in the silicon rubber during the melting process and the parent Eu-complex particles had positive effects on fluorescent property, whereas the re-crystallized Eu-complex particles and the aggregating complexes formed during the melting-process had negative effects on fluorescent property. For the uncured composites, their fluorescent intensities almost did not change with the increasing amount of Eu-complex. Furthermore, for the composites with small content of Eu-complex, their fluorescent intensities decreased significantly after curing, and this difference in fluorescent intensity became smaller as the content of Eu-complex increases.

Luminescent properties of Eu(OA)3(TTA)/NBR composites prepared by in-situ reaction

Eu(OA)3(TTA) (OA=cis-9-octadecenoic acid, TTA=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione) complexes (Eu- complexes) containing the ligand OA with long molecular chains were synthesized. The Eu(OA)3(TTA) complexes and peroxide were added into nitrile-butadiene rubber (NBR) by mechanical shearing to get the uncured composites. The cured composites were obtained by vulcanizing the uncured composites at high temperature. The in-situ reaction including polymerization and grafting of Eu-complex took place at the curing process, which was verified by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations showed the fine dispersion of Eu(OA)3(TTA) complex (Eu-complex) in the cured composites compared with the uncured ones. Fluorescent spectra and Judd-Ofelt parameters analysis revealed that the fluorescent intensity increased approximate linearly with the content of Eu- complex increasing due to the in-situ reaction and long molecular chains of OA. The fluorescent lifetime of composites was longer than that of original Eu-complexes.

Eu(TTA)2 (phen) (UAH)/SiR Fluorescence Materials Prepared by In-Situ Reaction Method

Abstract Eu(TTA)2(phen) (UAH) (UAH = undecylenic acid) with fine fluorescent property and active group was synthesized. The measurement and characterization of complexes were also carried out. A series of composites based silicon rubber were prepared by blending silicon rubber and Eu(TTA)2(phen) (UAH) rare earth complex with active groups. Next, the effect of vulcanizing time on the property of materials was mainly studied. The results show that the dispersed particle size of rare earth complexes decreases gradually in the vulcanizing process.

Exploration of Reactivity of Eu(TTA)2(phen) (MA)

Abstract The reactivity of Eu (TTA) 2 (phen) (MA) (HTTA = 2-thenoyltrifluoroacetone, MA = maleic anhydride) was studied. A series of products were prepared by direct polymerization, suspension polymerization, and alternate suspension and solution copolymerization with the styrene. And then we reactivity of these products were studied. The complexes were investigated and characterized by X-ray Diffraction (XRD), gel permeation chromatography (GPC) and fluorescence spec-trophotometer. Although high polymerization degree is not found in the exploration of reactivity, it is found that the fluorescent intensity of complexes prepared by suspension polymerization increases significantly compared with the original particles, which is five times higher than that of the pure rare earth complex.

Influence of Blending Temperature on Fluorescence Properties of Silicone Rubber Matrix Eu(TTA)2(phen)(MA) Composites

A series of fluorescent composites were prepared by blending silicone rubber with Eu(TTA)2(phen)(MA). The influence of mechanical blending temperature on fluorescent intensity of composites and dispersion of rare earth complexes in the SiR matrix were investigated. As for the cured rubber, it is found that its fluorescent intensity is relatively low compared with that of uncured rubber. Low temperature is beneficial to dispersion of Eu(TTA)2(phen)(MA) homogeneously. When the amount of rare earth complexes is low, the fluorescent intensity of composites prepared by mechanical blending method above melting point of Eu(TTA)2(phen)(MA) is much higher than that of composites prepared below melting point.