Rare earth metal containing polymers. 3. Characterization of ion-containing polymer structures using rare earth metal fluorescence probes

Single-Component Color-Tunable Gd(pic)3: Eu3+ Phosphor Based on a Metal-Organic Framework for Near-UV White-Light-Emitting Diodes

Compared with their multicomponent analogues, single-component white-light-emitting diodes (WLEDs) can eliminate the disadvantages such as high cost, fluorescence self-absorption, poor machinability, and reproducibility, but how to produce white light with high quality in a single-phase host is still a big challenge. In the work, a series of Eu³⁺/Tb³⁺-doped Gd(pic)₃ and La(pic)₃ are obtained through solvothermal conditions with picolinic acid (Hpic) and lanthanide nitrate. Researchers could regularly modulate the emitting color of phosphors by adjusting the excitation wavelength as well as the relative concentration of Ln³⁺ ions to obtain white light. Different luminance values [especially quantum yield (QYs)] between host materials Gd(pic)₃ and La(pic)₃ are investigated, which shows that doping of Eu³⁺ into Gd(pic)₃ can improve QY to a great extent. By employing Gd_0.9512Eu_0.0488(pic)₃ and Gd_0.9141Eu_0.0451Tb_0.0408(pic)₃ as phosphors, we successfully fabricated two excellent near-ultraviolet (365 nm) WLEDs with CIE chromaticity coordinates (0.3052, 0.3462) and (0.3007, 0.3448), relatively low color-correlated temperature (6755, 7001 K), and high color rendering index (R _a = 71.8, 72.9). This approach may open a new prospect for developing single-phase near-ultraviolet phosphors with high efficiency.

Synthesis and photoluminescence properties of europium(III) complexes sensitized with β-diketonato and N, N-donors ancillary ligands

Synthesis of three new europium(III) complexes with 1,3-[bis(4-methoxyphenyl)]propane-1,3-dionato (HBMPD) ligand and ancillary ligands such as 2,2'-biquinoline (biq) or neocuproine (neo) has been reported in this report. The synthesized complexes were characterized by IR (infrared), ¹H and ¹³C NMR (nuclear magnetic resonance) spectroscopy, CHN (carbon, hydrogen and nitrogen) elemental analysis, XRD (X-ray diffraction), TGA (thermogravimetric analysis) and photoluminescence (PL) spectroscopy. The emission spectra of europium(III) complexes displayed both the low intensity ⁵D_1-3→⁷F_0-3 transitions in 410-560nm blue-green region and high intensity characteristic ⁵D₀→⁷F_0-3 transitions in 575-640nm orange-red region correspond to the emission of ancillary ligands and europium ion respectively, which can lead to white luminescence due to integration of blue, green and red color emissions. The photoluminescence investigations indicate that the absorbed energy of the HBMPD ligand transferred to the central europium(III) ion in an efficient manner, which clearly explained by antenna effect. The excellent results of thermal behavior and photophysical properties like luminescence spectra, CIE (Commission Internationale Eclairage) chromaticity coordinates, luminescence decay curves and high quantum efficiency of the complexes make them a promising component of the white light-emitting diodes in display devices.

Optical Features of Efficient Europium(III) Complexes with β-Diketonato and Auxiliary Ligands and Mechanistic Investigation of Energy Transfer Process

Two new europium (III) complexes have been synthesized with 1,3-[bis(4-methoxyphenyl)]propane-1,3-dionato (HBMPD) as main ligand and 2,2'-bipyridyl (bipy) or 1,10-phenanthroline (phen) as an auxiliary ligand. The main ligand HBMPD has been synthesized by ecofriendly microwave approach and complexes by solution precipitation method. The resulting materials are characterized by IR, (1)H-NMR, elemental analysis, X-ray diffraction, UV-visible and TG-DTG techniques. The photoluminescence (PL) spectroscopy depicts the detail analysis of photophysical properties of the complexes, their results show that the ligand interact with Eu (III) ion which act as antenna and transfers the absorbed energy to the central europium(III) ion via sensitization process efficiently. As a consequence of this interaction, these materials exhibit excellent luminescent intensity, long decay time (τ), high quantum efficiency (η) and Judd-Ofelt intensity parameter (Ω2). The CIE coordinates fall under the deep red region, matching well with the NTSC (National Television Standard Committee) standard. Hence, these highly efficient optical materials can be used as a red component in organic light emitting diodes (OLEDs) and full color flat panel displays.

Synthesis and characterization of a Eu-containing polymer precursor featuring thenoyltrifluoroacetone and 5-acrylamido-1,10-phenanthroline

A polymerizable ligand, 5-acrylamido-1,10-phenanthroline (L), was synthesized. Its Eu(III) complex with 2-thenoyltrifluoroacetone (HTTA) was prepared and characterized by elemental analysis, IR, MS, and (1)H NMR spectra. The photophysical properties of the complex were studied in detail by using UV, luminescence spectra, luminescence lifetime and quantum yield. The complex shows a remarkable luminescence quantum yield at room temperature (40.1%) upon ligand excitation and a long (5)D(0) lifetime (590 μs), which makes it not only a promising light-conversion molecular device but also an excellent luminescent polymer precursor.

Stabilization of neodymium oxide nanoparticles via soft adsorption of charged polymers

In this work, two synthetic polyelectrolytes, PSS and PAH, are employed as strong adsorbed surfactants to disperse and stabilize neodymium oxide nanoparticles. The acid-base equilibria of the oxide surfaces of the particles were investigated under different pH conditions in the absence and presence of polyelectrolytes, to optimize particle stabilization through enhancement of the effective repulsive surface charges. Surface charge amplification of a 3:5 ratio was achieved to permit improved particle transparency of 100-fold in visible wavelengths in neutral and acidic pH regimes, and a stable 10-fold surface charge amplification was achieved under basic pH conditions. The potential of polyelectrolytes as stabilizing agents for neodymium oxide NPs in large-scale particle physics experiments requiring extremely high optical transparency over long path length is evaluated based on optical absorbance and particle stability.

Optical Properties of Lanthanide Metal Ion Polymer Complexes

The fluorescent characteristics of lanthanide chelates are of considerable interest in connection with electronic energy transfer processes and with their use in laser systems. We have synthesized various chelating groups, such as diketone and bypyridyl containing polymers and prepared their Tb3+ and Eu3+ complexes. Their fluorescent properties in connection with a possible laser action were investigated.

Electroluminscence (EL) in organic compounds has been investigated from fundamental as well as practical point of views. Various organic dyes were utilized as emitter materials in EL devices. In these examples, owing to the broad nature of the luminescence spectra of organic dyes, the luminescent colors are dull. We have utilized lanthanide metal ion complexes as a luminescent emitter.

Tb and Eu ion complexes emitted sharp green and red light, respectively. The configuration of the EL cell and experimental results are described.

Isophthalato-Based 2D Coordination Polymers of Eu(III), Gd(III), and Tb(III): Enhancement of the Terbium-Centered Luminescence through Thiophene Derivatization

We present here the first examples of lanthanide ion complexes with only isophthalic acid or thiophenylisophthalic acid ligands. The complexes of isophthalic acid with Eu(3+) (1) and Tb(3+) (2) and the moderately soluble complexes of 5-thiophen-3-ylisophthalate with Eu(3+) (3), Gd(3+) (4), and Tb(3+) (5) were isolated as single crystals through gel crystallization. X-ray diffraction studies confirm the cross-linking structure of these complexes, which, in case of the thiophenyl derivatives, results in low solubility in common solvents. The two-dimensional isophthalato complex of Eu(3+) (1) crystallizes in the C2/c space group, with a = 22.154(4), b = 12.649(3), and c = 15.921(3) A, beta = 112.34(3) degrees, and V = 4126.7(14) A(3), while the one-dimensional Tb(3+) complex of the same ligand, 2, crystallizes in the space group P2(1)/c with a = 11.921(2), b = 10.838(2), and c = 17.499(4) A, beta = 92.44(3) degrees, and V = 2258.9(8) A(3). The thiophenylisophthalato complexes of Eu(3+) (3) and Gd(3+) (4) are two-dimensional and crystallize in the P2/n space group with parameters for 3 of a = 14.139(3), b = 10.684(2), and c = 15.138(3) A, beta = 102.51(3) degrees, and V = 2232.3(8) A(3) and parameters for 4 of a = 14.1195(13), b = 10.6594(10), and c = 15.1149(14) A, beta = 102.529(2) degrees, and V = 2220.7(4) A(3), while the Tb(3+) complex, 5, also two-dimensional, crystallizes in the P space group with a = 11.051(2), b = 14.528(3), and c = 15.041(3) A, alpha = 77.63(3), beta = 87.86(3), and gamma = 83.51(3) degrees, and V = 2343.48 A(3). All complexes of Eu(3+) and Tb(3+) luminesce in aqueous solution, and the luminescence lifetimes and quantum yields are 123.8 +/- 7.4, 0.14% (1), 475.1 +/- 14.5, 3.58% (3), 129.3 +/- 3.5, 0.19% (4), and 213.9 +/- 2.2 micros, 7.46% (5).