N-Rich Porous Polymer with Isolated Tb3+ -Ions Displays Unique Temperature Dependent Behavior through the Absence of Thermal Quenching

The challenge of measuring fast moving or small scale samples is based on the absence of contact between sample and sensor. Grafting lanthanides onto hybrid materials arises as one of the most promising accurate techniques to obtain noninvasive thermometers. In this work, a novel bipyridine based porous organic polymer (bpyDAT POP) was investigated as temperature sensor after grafting with Eu(acac)₃ and Tb(acac)₃ complexes. The bpyDAT POP successfully showed temperature-dependent behavior in the 10-310 K range, proving the potential of amorphous, porous organic frameworks. We observed unique temperature dependent behavior. More intriguingly, instead of the standard observed change in emission as a result of a change in temperature for both Eu³⁺ and Tb³⁺ , the emission spectrum of Tb³⁺ remained constant. This work provides framework- and energy-based explanations for the observed phenomenon. The conjugation in the bpyDAT POP framework is interrupted, creating energetically isolated Tb³⁺ environments. Energy transfer from Tb³⁺ to Eu³⁺ is therefore absent, nor energy back transfer from Tb³⁺ to bpyDAT POP ligand (i.e. no thermal quenching) is detected.

Eu3+ Sensitization via Nonradiative Interparticle Energy Transfer Using Inorganic Nanoparticles

Phosphors have been used successfully for both research and commercial applications for decades. Eu³⁺-doped materials are especially promising, because of their extremely stable, efficient, and narrow red emission lines. Although these emission properties are ideal for lighting applications, weak absorption in the blue spectral range has until now prevented the use of Eu³⁺-based phosphors in applications based on blue light-emitting diodes. Here, we demonstrate a sensitization mechanism of Eu³⁺ based on interparticle Förster resonance energy transfer (IFRET) between lanthanide-doped inorganic nanocrystals (NCs). Compared to co-doping different lanthanides in the same host crystal, IFRET allows an independent choice of host lattices for Eu³⁺ and its sensitizer while potentially greatly reducing metal-to-metal charge transfer quenching. We demonstrate IFRET between NCs, resulting in red Eu³⁺ emission upon blue excitation at 485 nm using LaPO₄:Tb/LaPO₄:Eu and LaPO₄:Tb/YVPO₄:Eu NC mixtures. These findings pave the way toward engineering blue-sensitized line emitters for solid-state lighting applications.

Binary activated iron oxide/SiO2/NaGdF4:RE (RE = Ce, and Eu; Yb, and Er) nanoparticles: synthesis, characterization and their potential for dual T1–T2 weighted imaging

Iron oxide/SiO₂/NaGdF₄:RE (RE = Ce, and Eu; Yb, and Er) NPs upon irradiation of (i) 254 nm UV light shows red lines in (Ce, and Eu) activated systems and (ii) a 980 nm NIR laser shows green lines and mid IR lines in (Yb, and Er) activated systems.

Lanthanide-Doped Core-Shell-Shell Nanocomposite for Dual Photodynamic Therapy and Luminescence Imaging by a Single X-ray Excitation Source

Photodynamic therapy (PDT) could be highly selective and noninvasive, with low side effects as an adjuvant therapy for cancer treatment. Because excitation sources such as UV and visible lights for most of the photosensitizers do not penetrate deeply enough into biological tissues, PDT is useful only when the lesions are located within 10 mm below the skin. In addition, there is no prior example of theranostics capable of both PDT and imaging with a single deep-penetrating X-ray excitation source. Here we report a new theranostic scintillator nanoparticle (ScNP) composite in a core-shell-shell arrangement, that is, NaLuF₄:Gd(35%),Eu(15%)@NaLuF₄:Gd(40%)@NaLuF₄:Gd(35%),Tb(15%), which is capable of being excited by a single X-ray radiation source to allow potentially deep tissue PDT and optical imaging with a low dark cytotoxicity and effective photocytotoxicity. With the X-ray excitation, the ScNPs can emit visible light at 543 nm (from Tb³⁺) to stimulate the loaded rose bengal (RB) photosensitizer and cause death of efficient MDA-MB-231 and MCF-7 cancer cells. The ScNPs can also emit light at 614 and 695 nm (from Eu³⁺) for luminescence imaging. The middle shell in the core-shell-shell ScNPs is unique to separate the Eu³⁺ in the core and the Tb³⁺ in the outer shell to prevent resonance quenching between them and to result in good PDT efficiency. Also, it was demonstrated that although the addition of a mesoporous SiO₂ layer resulted in the transfer of 82.7% fluorescence resonance energy between Tb³⁺ and RB, the subsequent conversion of the energy from RB to generate ¹O₂ was hampered, although the loaded amount of the RB was almost twice that without the mSiO₂ layer. A unique method to compare the wt % and mol % compositions calculated by using the morphological transmission electron microscope images and the inductively coupled plasma elemental analysis data of the core, core-shell, and core-shell-shell ScNPs is also introduced.

(Lu0.3Gd0.7)2SiO5:Y3+ single crystals grown by the laser floating zone method: structural and optical studies

Laser floating zone growth of transparent Y0.05:(Lu0.3Gd0.7)2SiO5 single crystals suitable as laser host materials.

Facile hydrothermal synthesis and multicolor-tunable luminescence of YPO4:Ln3+ (Ln = Eu, Tb)

This work investigates a novel facile hydrothermal conversion method for the synthesis of uniform cuboid YPO₄ and obtains multicolor emissions in YPO₄:Tb³⁺, Eu³⁺ samples, and the energy transfer efficiency reachs about 94.30%.