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Solvent-Dependent Sensitization of Ytterbium and Neodymium via an Intramolecular Excimer
摘要： We report the synthesis of a di(1-pyrenyl)-phosphoryl acetophenone ligand containing two pyrenyl moieties linked by a single phosphorus atom. The ligand exhibits solvent-dependent emission: in nonpolar solvents, typical monomeric pyrene emission is observed, whereas in polar solvents, an additional broad and structureless emission appears. The emission in polar solvents is concentration independent and is attributed to the emission of an intramolecular excimer. The coordination of the di(1-pyrenyl)phosphoryl acetophenone ligand as well as the corresponding deprotonated anionic di(1-pyrenyl)phosphoryl acetophenonate ligand was studied with the near-infrared emitting lanthanides, neodymium and ytterbium. Solvent-dependent sensitization of both lanthanides was observed and correlates with the presence of the excimer emission. Sensitization of ytterbium is more efficient than neodymium, and the overall quantum yields were found to be 12.8 and 1.9% for ytterbium and neodymium, respectively.
关键词： solvent-dependent emission,quantum yields,ytterbium,neodymium,intramolecular excimer,lanthanides
更新于2025-11-14 15:24:45
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Host Sensitized Lanthanide Photoluminescence from Post-synthetically Modified Semiconductor Nanoparticles Depends on Reactant Identity
摘要： This work investigates the photoluminescence characteristics where cadmium selenide (CdSe) and zinc sulfide (ZnS) nanoparticles are treated post-synthetically by the trivalent lanthanide cations (Ln3+) [Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb] separately to form either CdSe/Ln or ZnS/Ln nanoparticles. Host sensitized Ln3+ emission was found to be present only in CdSe/Eu, CdSe/Tb, ZnS/Eu, ZnS/Tb and ZnS/Yb nanoparticles. In all the cases tuning of emission of the nanoparticles has been observed, irrespective of the presence or absence of host sensitization. The elemental compositions of CdSe and ZnS nanoparticles upon post-synthetic treatment show a remarkable difference. Incorporation of lanthanides in the nanoparticles is evident with significant alteration in the anionic content, and complete cation exchange of either Cd2+ or Zn2+ by Ln3+ has not been detected; as evaluated from energy dispersive X-ray spectroscopy. Further evaluation on this comes from considering thermodynamic parameters of inter cation interaction. In cases where the host sensitized Ln3+ emission have been observed, luminescence lifetime measurements reveal significant protection of Ln3+ in the nanoparticles. Noticeable difference in photophysical properties for a given Ln3+ has been realized in the two hosts. The photophysical observations have been rationalized using (i) charge trapping mediated host sensitized dopant emission, (ii) autoionization of excited electrons, and (iii) environment induced photoluminescence quenching. The post-synthetic modification discussed in the present work provides an easy and less synthetically demanding room temperature based protocol to avail lanthanide incorporated (doped) semiconductor nanoparticles that can potentially use the unique emission properties of the lanthanide cations.
关键词： Semiconductor Nanoparticles,Host Sensitization,Trivalent Lanthanides,Photoluminescence,Post-synthetic Modification
更新于2025-09-23 15:23:52
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Complexation of the Mycotoxin Cyclopiazonic Acid with Lanthanides Yields Luminescent Products
摘要： Cyclopiazonic acid (CPA) is a neurotoxin that acts through inhibition of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA). CPA blocks the calcium access channel of the enzyme. The inhibition may involve the binding of CPA with a divalent cation such as Mg2+. The potential for CPA to act as a chelator also has implications for methods to detect this toxin. Certain of the lanthanide metals undergo a dramatic increase in luminescence upon coordination with small molecules that can transfer excitation energy to the metal. This report is the first to describe the coordination of CPA with lanthanide metals, resulting in a substantial enhancement of their luminescence. The luminescence expressed was dependent upon the type of lanthanide, its concentration, and the environment (solvent, water content, pH). Based upon the phenomenon, a competitive assay was also developed wherein terbium (Tb3+) and a series of metal cations competed for binding with CPA. With increasing cation concentration, the luminescence of the CPA/Tb3+ complex was inhibited. The chlorides of ten metals were tested. Inhibition was best with Cu2+, followed by Co2+, Al3+, Fe3+, Mn2+, Au3+, Mg2+, and Ca2+. Two cations in oxidation state one (Na+, K+) did not inhibit the interaction significantly. The interaction of CPA with lanthanides provides a novel recognition assay for this toxin. It also provides a novel way to probe the binding of CPA to metals, giving insights into CPA's mechanism of action.
关键词： mechanism of action,lanthanides,calcium-ATPase,luminescence,mycotoxin,cyclopiazonic acid
更新于2025-09-23 15:22:29
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A New Generation of NIR-II Probes: Lanthanide-Based Nanocrystals for Bioimaging and Biosensing
摘要： Fluorescence-based imaging in the second near infrared window (NIR-II, 1000–1700 nm) is extensively used in both fundamental scientific research and clinical practice, owing to its advances of high sensitivity and high spatiotemporal resolution with increasing tissue penetration depths. Among several NIR-II fluorophores, recent accomplishments in biocompatible lanthanide-based luminescent nanomaterials have aroused great interest of researchers. This progress report summarizes recent progress in controlled synthesis of lanthanide-based NIR-II nanomaterials and their state-of-the-art in NIR-II biomedical imaging and biosensing applications. In addition, challenges and opportunities for this kind of novel NIR-II nanoprobes are also discussed.
关键词： lanthanides,bioimaging,NIR-II,near infrared imaging,fluorescence,nanoparticles
更新于2025-09-23 15:22:29
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Modulating the photocatalytic activity of TiO2 (P25) with lanthanum and graphene oxide
摘要： The modulation and tuning of the photocatalytic activity of commercial titanium dioxide (TiO2) P25 nanoparticles is demonstrated through the incorporation of lanthanum (La) and/or graphene oxide (GO). These composite materials, which could have applications in commercial products, were prepared by a two-step hydrothermal method from the corresponding precursors. The effect of La (0.05 - 2 mol%) and GO (5 m%) content on the crystal structure, morphology and photocatalytic activity of TiO2 was investigated by XRS, SEM, EDS, TEM, UV-visible DRS, point of zero charge, photoluminescence and the decolorization of methylene blue. Lanthanum modified the recombination rate of the photogenerated electron-hole charges on TiO2 by inducing an increase in the structural defects, which resulted in a significant suppression, up to 90%, of the photocatalytic activity in the UVA light region. In contrast, the addition of GO enhanced the photocatalytic activity of TiO2. Materials with tuned intermediate photoactivity within the entire range from high to very low were prepared by dosing appropriate amounts of La and GO species. The strategy of combining La and GO represents a useful and simple method for tuning or for suppressing the photocatalytic activity of TiO2 under UVA light irradiation in materials and consumer products using TiO2.
关键词： lanthanides,rare earths,titanium dioxide,graphene oxide
更新于2025-09-23 15:21:21
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Picomolar Biosensing and Conformational Analysis Using Artificial Bidomain Proteins and Terbiuma??Toa??Quantum Dot F??rster Resonance Energy Transfer
摘要： Although antibodies remain a primary recognition element in all forms of biosensing, functional limitations arising from their size, stability, and structure have motivated the development and production of many different artificial scaffold proteins for biological recognition. However, implementing such artificial binders into functional high-performance biosensors remains a challenging task. Here, we present the design and application of F?rster resonance energy transfer (FRET) nanoprobes comprised of small artificial proteins (αRep bidomains) labeled with a Tb complex (Tb) donor on the C-terminus and a semiconductor quantum dot (QD) acceptor on the N-terminus. Specific binding of one or two protein targets to the αReps induced a conformational change that could be detected by time-resolved Tb-to-QD FRET. These single-probe FRET-switches were used in a separation-free solution-phase assay to quantify different protein targets at subnanomolar concentrations and measure the conformational changes with subnanometer resolution. Probing ligand-receptor binding under physiological conditions at very low concentrations in solution is a special feature of FRET that can be efficiently combined with other structural characterization methods to develop, understand, and optimize artificial biosensors. Our results suggest that the αRep FRET nanoprobes have a strong potential for their application in advanced diagnostics and intracellular live cell imaging of ligand-receptor interactions.
关键词： protein structure,molecular ruler,lanthanides,molecular diagnostics,FRET,binding assay
更新于2025-09-23 15:21:01
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High Emission Quantum Yield Tb <sup>3+</sup> -Activated Organic-Inorganic Hybrids for UV-Down-Shifting Green Light-Emitting Diodes
摘要： Solid-state light-emitting diodes (LEDs) are driving the lighting industry towards efficient and environmentally friendly lighting and displays. Current challenges encompass efficient and low-cost down-shifting phosphors with tuned emission colors. Green light lies on the low-loss optical transmission window in plastic optical fibers and plays a special role in human and plants circadian rhythm regulation. Moreover, green-emitting phosphors may suppress the ‘green gap’ found in semiconductor-based LEDs. In this work, a UV-photostable Tb(NaI)3(H2O)2, with (1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-NaI= nalidixic naftiridine-3-carboxylic acid), was incorporated into tripodal organic-inorganic hybrid materials. The hybrid hosts boost the absolute emission quantum yield from ~0.11 (isolated complex) to ~0.82 (doped hybrid), being the largest value reported for Tb3+-based hybrid phosphors. A green-emitting LED was fabricated by coating a near-UV LED (365 nm) with a Tb3+-activated organic-inorganic hybrid showing pure-green light with Commission International de l’Eclairage color coordinates and an efficacy value of (0.33, 0.59) and 1.3 lm·W?1, respectively.
关键词： near-UV light-emitting diodes,green light-emitting diodes,lanthanides,solid-state lighting,organic-inorganic hybrids
更新于2025-09-23 15:21:01
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Magnetic and Luminescence Properties of Two Dinuclear Lanthanide Complexes with Butterfly-like Arrangement
摘要： Two dinuclear lanthanide complexes with pentadentate ligand 3-[bis(pyridine-2-ylmethyl)amino]propane-1,2-diol (H2L), formulated as [Ln2(HL)2(NO3)2(H2O)2]·1.5NO3·0.5I [Ln = Tb (ZTU-1) and Eu (ZTU-2); ZTU = Zhaotong University] were synthesized and structurally characterized. ZTU-1 and ZTU-2 are isomorphous and feature a butterfly-like arrangement. The fluorescence properties of ZTU-1 and ZTU-2 are investigated and slow magnetic relaxation behavior is observed in ZTU-1.
关键词： Lanthanides,Slow magnetic relaxation,Luminescence,Dinuclear lanthanide complex
更新于2025-09-23 15:21:01
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Eye safe emission in Tm3+/Ho3+ and Yb3+/Tm3+ co-doped optical fibers fabricated using MCVD-CDS system
摘要： The RE-co-doped silica optical fibers emitting in the eye-safe spectral range are still attractive for new applications like LIDAR, pollution monitoring, navigation, and free-space optical communication. High gain and beam quality of fiber sources based on large mode area (LMA) active fibers can be fabricated by the well-known Modified Chemical Vapor Deposition (MCVD) technology improved by the chelate doping system. Considering silica matrix, the most interesting co-dopants in the region above 1400 nm are thulium and holmium. In the paper Tm3t/Ho3t and Yb3t/Tm3t co-doped silica optical fibers (refractive index and rare earth distribution profile, luminescence) are presented. Their respective emission spectra has been measured over the range 1550–2150 nm for Tm3t/Ho3t (exc. at 796 nm) and 1600–2100 nm for Yb3t/Tm3t (exc. at 976 nm). A wide luminescent spectrum has been recorded from RE co-doping of silica glass during the MCVD process and we were able to achieve the appropriate and uniform concentration for getting the conditions of energy transfer. The fabrication and characterization of Tm3t/Ho3t and Yb3t/Tm3t co-doped optical fibres are presented. The analysis of luminescence spectrum changes vs. fibre length has shown that there is Amplified Spontaneous Emission (ASE) at 1960 nm in Yb3t/Tm3t co-doped optical fibre. The possibilities of obtaining novel constructions of RE co-doped optical fibers for eye-safe emission region will be also shown.
关键词： Modified chemical vapor deposition (MCVD),Optical fibers,Lanthanides,Eye-safe emission
更新于2025-09-23 15:19:57
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Self-assembled Ln(III) cyclen-based micelles and AuNPs conjugates as candidates for luminescent and magnetic resonance imaging (MRI) agents
摘要： The tetra-substituted heptadentate cyclen (1,4,7,10-tetraazacyclododecane) based Eu(III)/Tb(III)/Gd(III)-complexes 1.Ln and 2.Ln were developed. 1.Eu/Tb and 2.Eu/Tb were employed in the formation of luminescent self-assembling ternary structures, and we demonstrate that only in the presence of appropriate sensitizing antennae, was the lanthanide-emission of 1.Eu/Tb and 2.Eu/Tb ‘switched on’. 1.Gd/2.Gd were developed as potential MIR contrast agents, and employed in NMRD-measurements, where their relaxivity was investigated, and their (relatively high) r1 values determined. The formation of a self-assembled micelle-type structure was clearly observed for 2.Gd. The functionalised gold nanoparticles 1.Ln-AuNP were also synthesized from 1.Ln. As for the free complexes, the Ln-emission was ‘switched on’ for 1.Eu/Tb-AuNP in the presence of the antennae. NMRD measurements indicated that the relaxivity for the 1.Gd-AuNP systems was very high, with a value of 445 s-1mM-1 (at 400 MHz), demonstrating the cumulative effect of the relatively high number of 1.Gd complexes on the surface of the AuNP.
关键词： gold nanoparticles,lanthanides,Supramolecular chemistry,luminescence,MRI contrast agents,cyclen complexes
更新于2025-09-23 15:19:57