Red-Green Emitting and Superparamagnetic Nanomarkers Containing Fe₃O₄ Functionalized with Calixarene and Rare Earth Complexes

The design of bifunctional magnetic luminescent nanomaterials containing Fe₃O₄ functionalized with rare earth ion complexes of calixarene and β-diketonate ligands is reported. Their preparation is accessible through a facile one-pot method. These novel Fe₃O₄@calix-Eu­(TTA) (TTA = thenoyltrifluoroacetonate) and Fe₃O₄@calix-Tb­(ACAC) (ACAC = acetylacetonate) magnetic luminescent nanomaterials show interesting superparamagnetic and photonic properties. The magnetic properties (M-H and ZFC/FC measurements) at temperatures of 5 and 300 K were explored to investigate the extent of coating and the crystallinity effect on the saturation magnetization values and blocking temperatures. Even though magnetite is a strong luminescence quencher, the coating of the Fe₃O₄ nanoparticles with synthetically functionalized rare earth complexes has overcome this difficulty. The intramolecular energy transfer from the T₁ excited triplet states of TTA and ACAC ligands to the emitting levels of Eu³⁺ and Tb³⁺ in the nanomaterials and emission efficiencies are presented and discussed, as well as the structural conclusions from the values of the 4f–4f intensity parameters in the case of the Eu³⁺ ion. These novel nanomaterials may act as the emitting layer for the red and green light for magnetic light-converting molecular devices (MLCMDs)

Red-Green Emitting and Superparamagnetic Nanomarkers Containing Fe₃O₄ Functionalized with Calixarene and Rare Earth Complexes

The design of bifunctional magnetic luminescent nanomaterials containing Fe₃O₄ functionalized with rare earth ion complexes of calixarene and β-diketonate ligands is reported. Their preparation is accessible through a facile one-pot method. These novel Fe₃O₄@calix-Eu­(TTA) (TTA = thenoyltrifluoroacetonate) and Fe₃O₄@calix-Tb­(ACAC) (ACAC = acetylacetonate) magnetic luminescent nanomaterials show interesting superparamagnetic and photonic properties. The magnetic properties (M-H and ZFC/FC measurements) at temperatures of 5 and 300 K were explored to investigate the extent of coating and the crystallinity effect on the saturation magnetization values and blocking temperatures. Even though magnetite is a strong luminescence quencher, the coating of the Fe₃O₄ nanoparticles with synthetically functionalized rare earth complexes has overcome this difficulty. The intramolecular energy transfer from the T₁ excited triplet states of TTA and ACAC ligands to the emitting levels of Eu³⁺ and Tb³⁺ in the nanomaterials and emission efficiencies are presented and discussed, as well as the structural conclusions from the values of the 4f–4f intensity parameters in the case of the Eu³⁺ ion. These novel nanomaterials may act as the emitting layer for the red and green light for magnetic light-converting molecular devices (MLCMDs)

Luminescent Analysis of Eu³⁺ and Tb³⁺ Flufenamate Complexes Doped in PMMA Polymer: Unexpected Terbium Green Emission under Sunlight Exposure

The design of efficient luminescent lanthanide materials with a wide range of different excitation wavelengths in the UVA, UVB, and UVC regions, as well as under sunlight exposure, is highly desirable for application as molecular light-converting devices. In this work, [Ln(fluf)3(L)] complexes (Ln3+: Eu, Gd, and Tb) and doped PMMA:(1%)Tb(fluf)3(L) films, where fluf stands for the flufenamate ligand and L is H2O, phen, tppo, topo, and dpso, were successfully prepared by a facile one-pot method, and their photophysical properties were also investigated. The Ln3+ compounds were characterized by elemental analysis, Fourier transform infrared absorption spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and diffuse reflectance spectroscopy techniques. The Eu3+ complexes present very weak emission intensities at 300 K temperature, showing very low intrinsic quantum yield (QEuEu) values due to a highly operative luminescence quenching by a low-lying ligand to metal charge transfer state. However, these values are significantly increased when obtained at low temperature (77 K). For Tb3+ complexes and the doped PMMA, polymeric films revealed an unprecedented bright emission under excitation at UVA, UVB, and UVC radiation. In addition, the doped polymers under sunlight exposure show the characteristic 5D4 → 7F6–0 transitions of the Tb3+ ion, exhibiting green emission color. These luminescent doped polymeric materials act as efficient energy harvesters and converters. Hence, the optical results show that the PMMA:(1%)Tb(fluf)3(L) photonic materials are highly versatile and desirable, presenting suitable application as efficient light-converting molecular devices and as luminescent solar concentrators

Rare Earth-Indomethacinate Complexes with Heterocyclic Ligands: Synthesis and Photoluminescence Properties

<div><p>In this work, synthesis, characterization and photophysical properties of trivalent rare earth complexes with a nonsteroidal anti-inflammatory drug [the indomethacinate (indo), presenting formulas RE(indo)3(H2O)x (x = 3, for Eu3+ and Gd+3, and x = 4 for Tb+3), RE(indo)3(bipy) and RE(indo)3(phen) (bipy: 2,2'-bipyridine, and phen: 1,10-phenanthroline)] were investigated. Based on photoluminescent results, the intramolecular energy transfer process from T1 triplet states of indo, phen and bipy ligands to the 5D0 emitting level of the Eu3+ ion in the coordination compounds is discussed. Accordingly, it is proposed two possible intramolecular energy transfer mechanisms between indomethacinate ligand and rare earth ions, which involve the participation of excited electronic states of the heterocyclic ligands as intermediate ones.</p></div

Synthesis and Characterization of the Europium(III) Pentakis(picrate) Complexes with Imidazolium Countercations: Structural and Photoluminescence Study

Six new lanthanide complexes of stoichiometric formula (C)₂[Ln­(Pic)₅]where (C) is a imidazolium cation coming from the ionic liquids 1-butyl-3-methylimidazolium picrate (BMIm-Pic), 1-butyl-3-ethylimidazolium picrate (BEIm-Pic), and 1,3-dibutylimidazolium picrate (BBIm-Pic), and Ln is Eu­(III) or Gd­(III) ionshave been prepared and characterized. To the best of our knowledge, these are the first cases of Ln­(III) pentakis­(picrate) complexes. The crystal structures of (BEIm)₂[Eu­(Pic)₅] and (BBIm)₂[Eu­(Pic)₅] compounds were determined by single-crystal X-ray diffraction. The [Eu­(Pic)₅]^2– polyhedra have nine oxygen atoms coordinated to the Eu­(III) ion, four oxygen atoms from bidentate picrate, and one oxygen atom from monodentate picrate. The structures of the Eu complexes were also calculated using the sparkle model for lanthanide complexes, allowing an analysis of intramolecular energy transfer processes in the coordination compounds. The photoluminescence properties of the Eu­(III) complexes were then studied experimentally and theoretically, leading to a rationalization of their emission quantum yields