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Tunable multi-color luminescence and white emission in lanthanide ion functionalized polyoxometalate-based metal–organic frameworks hybrids and fabricated thin films
摘要： In this paper, luminescent hybrid material systems are prepared with porous polyoxometalate-based metal-organic framework (POM-based MOF)[La(H2O)4(pdc)]4}[SiMo12O40]$2H2O (1) through the introduction of lanthanide ions (Ln3+, Ln = Eu, Tb, Sm, Dy, Eu/Tb, Dy/Eu) by a solvothermal approach. The POM-based MOF serves as a host for protecting the luminescence of Ln3+ cations. The structure, thermal stability, ultraviolet absorption and visible light emission of the target hybrid materials are determined with powder X-rays diffraction patterns (PXRD), Fourier transform infrared spectra (FTIR), thermal-gravimetric analysis (TGA), inductively coupled plasma-mass spectrometry (ICP-MS) analysis, energy dispersive spectrometer (EDS), ultraviolet visible diffusion reflections spectra (UV-vis DRS) and especially luminescence spectra. The final luminescence of the Ln3+ hybrids can be adjusted by changing the composition of Ln3+ cations or converting the excitation wavelengths of them. Among [La0.95Dy0.045Eu0.005(H2O)4(pdc)]4}[SiMo12O40]$2H2O (Dy3+/Eu3+@1) emits white luminescence under the excitation at 295 nm and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinate of it is (0.361, 0.3408). Moreover, we manufacture POM-based MOF thin films by using ethyl methacrylate (EMA) to assemble the POM-based MOF on a quartz plate as substrate. The hybrid thin films based on {La0.95Eu0.05(H2O)4(pdc)]4}[SiMo12O40]$2H2O (Eu3+@1) and La0.95Eu0.04Tb0.01(H2O)4(pdc)]4}[SiMo12O40]$2H2O (Eu3+/Tb3+@1) can also achieve white-light. The CIE chromaticity coordinates of them are (0.3425, 0.2548) and (0.3857, 0.3377), respectively.
关键词： Thin film,Lanthanide functionalization,Photofunctional hybrid material,Polyoxometallate based metal-organic frameworks,Luminescence
更新于2025-09-09 09:28:46
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Five 3D lanthanide-based coordination polymers with 3,3,6T13 topology: Structures and luminescent sensor for Hg2+ and Pb2+ ions
摘要： A series of isostructural lanthanide coordination polymers Ln-CPs, {[Ln2(PBA)3(H2O)3]?DMF?3H2O}n (Ln = La 1, Nd 2, Sm 3, Eu 4, Dy 5), based on a tripodal nitrogen-containing carboxylic ligand (H2PBA=5-(4-pyridin-3-yl-benzoylamino)-isophthalic acid), have been successfully synthesized under solvothermal conditions. Structural analyses show that compounds 1-5 are isomorphous and crystallize in triclinic space group Pī, and feature an interesting 3,3,6T13 network topology with point symbol (4·52)2(42·52·10·6·72)(58·64·10·6·72). There exist two kinds of 1D metal-carboxylate chains, which are further extended into 3D framework through the connection of PBA2- ligands. Moreover, luminescent spectra of compound 4 are also investigated in visible region, which indicates that it could be used to detect toxic metal cations with relatively high sensitivity and selectivity towards Hg2+ and Pb2+ in DMF solvent.
关键词： Hg2+,3,3,6T13 topology,luminescent sensor,Pb2+,lanthanide coordination polymers
更新于2025-09-09 09:28:46
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Helicenic complexes of lanthanide: influence of f-element on the inter-system crossing efficiency and competition between luminescence and oxygen sensitization.
摘要： The coordination of a helicen functionalized bipyridine to various lanthanide complexes (Ln = Y, Eu, Yb, Gd) led to the formation of an isostructural series. The photophysical study indicated that non-emissive lanthanide act as heavy atoms strongly enhancing the singlet oxygen generation. We also demonstrated that sensitization of the f-f luminescence is in competition with singlet oxygen generation.
关键词： singlet oxygen generation,lanthanide,photodynamic therapy,luminescence,helicen
更新于2025-09-09 09:28:46
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A stoichiometric terbium-europium dyad molecular thermometer: energy transfer properties
摘要： The optical thermometer has shown great promise for use in the fields of aeronautical engineering, environmental monitoring and medical diagnosis. Self-referencing lanthanide thermo-probes distinguish themselves because of their accuracy, calibration, photostability, and temporal dimension of signal. However, the use of conventional lanthanide-doped materials is limited by their poor reproducibility, random distance between energy transfer pairs and interference by energy migration, thereby restricting their utility. Herein, a strategy for synthesizing hetero-dinuclear complexes that comprise chemically similar lanthanides is introduced in which a pair of thermosensitive dinuclear complexes, cycTb-phEu and cycEu-phTb, were synthesized. Their structures were geometrically optimized with an internuclear distance of approximately 10.6 ?. The sensitive linear temperature-dependent luminescent intensity ratios of europium and terbium emission over a wide temperature range (50–298 K and 10–200 K, respectively) and their temporal dimension responses indicate that both dinuclear complexes can act as excellent self-referencing thermometers. The energy transfer from Tb3+ to Eu3+ is thermally activated, with the most important pathway involving the 7F1 Eu3+ J-multiplet at room temperature. The energy transfer from the antenna to Eu3+ was simulated, and it was found that the most important ligand contributions to the rate come from transfers to the Eu3+ upper states rather than direct ligand–metal transfer to 5D1 or 5D0. As the first molecular-based thermometer with clear validation of the metal ratio and a fixed distance between the metal pairs, these dinuclear complexes can be used as new materials for temperature sensing and can provide a new platform for understanding the energy transfer between lanthanide ions.
关键词： temperature sensing,hetero-dinuclear complexes,lanthanide,energy transfer,optical thermometer
更新于2025-09-09 09:28:46
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Synthesis, photoluminescence and thermodynamics of two lanthanide coordination polymers with 5-nitroisophthalate
摘要： Two lanthanide-based metal–organic frameworks, [Tb2(5-nip)3(H2O)5·5H2O]n (1), and [Eu3(5-nip)4(5-Hnip)(H2O)7·9H2O]n (2) (5-H2nip = 5-nitroisophthalic acid), have been synthesized and structurally characterized. 1 features a unique 3D network with two distinct paddlewheel building blocks. 2 displays a 3D supramolecular framework with 1D channels occupied by free water molecules. Solid-state photoluminescence studies indicate that both the compounds 1 and 2 exhibit characteristic luminescence emission bands of the corresponding lanthanide ions in the visible region at room temperature. TG-DSC curves show that the dehydrated products of the title compounds exhibit high stability up to 400 °C. The enthalpy changes of liquid-phase reaction of formation for 1 and 2, (l), were determined at 298.15 K by a microcalorimeter to be (10.7 ± 0.1) kJ·mol-1 and (30.6 ± 0.1) kJ·mol-1, respectively. Based on a designed thermochemical cycle, that of solid-phase reaction of formation and the standard molar enthalpy of formation for 1, (s) and , were calculated to be (16.9 ± 0.6) kJ·mol-1 and -(3103.2 ± 15.3) kJ·mol-1, respectively. Those for 2 were (119.4 ± 0.8) kJ?mol-1 and -(4510.2 ± 17.4) kJ?mol-1, respectively. Combining the thermochemical data of the reactions and kinetic equations with the data of thermokinetic experiments, the fundamental thermodynamic and kinetic parameters were also achieved.
关键词： Microcalorimetry,Thermochemistry,Photoluminescence,Crystal structure,Lanthanide
更新于2025-09-09 09:28:46
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Highly-efficient, Chemically-stable, UV/blue Light Excitable Biluminescent Security Ink to Combat Counterfeiting
摘要： A strategy has been demonstrated to design a biluminescent security ink using Eu(TTA)3Phen (ETP) and fluorescein for protecting the currency and other essential documents viz. passport, bank cheque, certificates against counterfeiting. Biluminescent security ink exhibits strong red and green emission under 367 and 445 nm excitations, respectively. As it is quite challenging to prepare a material that possesses two prominent (green and red) and distinguishable colors upon excitation with two separate LEDs sources, emitting at different wavelengths, the biluminescent security ink would be hard to counterfeit as compared to the existing luminescent security ink that exhibits single color under UV light exposure. To check its feasibility for security application the patterns printed out using biluminescent security ink were kept under a hot and humid atmosphere for 150 days. Also, the ETP and fluorescein fluorophores were exposed to UV light for a prolonged time, which do not show any sign of deterioration in their luminescence intensities. Furthermore, to check their chemical stability printed patterns were also exposed to chemicals which have potential to wiped-out ink viz. detergent, ethanol, acetone, and sodium hypochlorite (bleach) solution and noticed that it is well stable against these chemicals. Because of the reasons mentioned above and easy availability of 367 and 445 nm LEDs at low cost, authors believe that the application of this biluminescent security ink can trigger to realize the full potential of this advanced security feature in detecting fake currency.
关键词： luminescence,lanthanide,security ink,anticounterfeiting,fluorescein
更新于2025-09-09 09:28:46
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Determination of Handedness in a Single Chiral Nanocrystal via Circularly Polarized Luminescence
摘要： The occurrence of biological homochirality is attributed to symmetry breaking mechanisms which are still debatable. Studies of symmetry breaking require tools for monitoring the population ratios of individual chiral nano-objects, such as molecules, polymers or nanocrystals. Moreover, mapping their spatial distributions may elucidate on their symmetry breaking mechanism. While luminescence is preferred for detecting single particle chirality due to its high signal to noise ratio, the typical low optical activity of chromophores limits its applicability. Here, we report on handedness determination of single chiral lanthanide based luminescent nanocrystals with a total photon count of 2×104. Due to the large emission dissymmetry we could determine the handedness of individual particles using only a single circular polarization component of the emission spectrum, without polarization modulation. A machine learning algorithm, trained to several spectral lineshape features, enabled us to determine and spatially map the handedness of individual nanocrystals with high accuracy and speed. This technique may become invaluable in studies of symmetry breaking in chiral materials.
关键词： chiroptical activity,circularly polarized luminescence,lanthanide nanocrystals,single-particle spectroscopy
更新于2025-09-09 09:28:46
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Gas Adsorption and Fluorescent Sensing Properties of Two Porous Lanthanide Metal-Organic Frameworks Based on 3,5-Bis(2-carboxy-phenoxy)-Benzoic Acid
摘要： Two porous isomorphic 3D Eu(Ⅲ)/Nd(Ⅲ) lanthanide metal?organic frameworks (Ln-MOFs), formulated as {[Eu(BCPB)(H2O)(DMF)]·H2O·1.5CH3OH}n (1) and {[Nd(BCPB)(H2O)(DMF)]·2H2O}n (2), have been designed and synthesized by using the tripodal ligand of 3,5-bis(2-carboxy-phenoxy)-benzoic acid (H3BCPB) under solvothermal condition. Complexes 1 and 2 display 3D (3,6)-c net with the point symbol of {4.62}2{42.610.83}. Furthermore, fluorescent measurements showed 1 has highly selective detection for Fe3+ and CrO4 2- ions in aqueous solution, which shows that it acts as a chemical sensor for detecting Fe3+/CrO4 2- in aqueous solution. Meanwhile, gas adsorption properties of 1 and 2 have also been studied at different temperatures for N2, CH4 and CO2.
关键词： Fluorescent Properties,Adsorption Properties,Lanthanide Metal?Organic Frameworks,3,5-Bis(2-Carboxy-Phenoxy)-Benzoic Acid
更新于2025-09-04 15:30:14
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Comparative Spectroscopic Investigation of Tm3+:Tellurite Glasses for 2-μm Lasing Applications
摘要： We performed a comparative spectroscopic analysis on three novel Tm3+:tellurite-based glasses with the following compositions Tm2O3:TeO2-ZnO (TeZnTm), Tm2O3:TeO2-Nb2O5 (TeNbTm), and Tm3+:TeO2-K2O-Nb2O5 (TeNbKTm), primarily for 2-μm laser applications. Tellurite glasses were prepared at different doping concentrations in order to investigate the effect of Tm3+ ion concentration as well as host composition on the stimulated emission cross sections and the luminescence quantum efficiencies. By performing Judd–Ofelt analysis, we determined the average radiative lifetimes of the 3H4 level to be 2.55 ± 0.07 ms, 2.76 ± 0.03 ms and 2.57 ± 0.20 ms for the TeZnTm, TeNbTm and TeNbKTm samples, respectively. We clearly observed the effect of the cross-relaxation, which becomes significant at higher Tm2O3 concentrations, leading to the quenching of 1460-nm emission and enhancement of 1860-nm emission. Furthermore, with increasing Tm2O3 concentrations, we observed a decrease in the fluorescence lifetimes as a result of the onset of non-radiative decay. For the 3H4 level, the highest obtained quantum efficiency was 32% for the samples with the lowest Tm2O3 ion concentration. For the 1860-nm emission band, the average emission cross section was determined to measure around 6.33 ± 0.34 × 10?21 cm2, revealing the potential of thulium-doped tellurite gain media for 2-μm laser applications in bulk and fiber configurations.
关键词： thulium-doped laser glasses,solid-state spectroscopy,lanthanide ion-doped glasses,glass lasers,2-micron lasers,thulium,tellurite glass
更新于2025-09-04 15:30:14
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Wide-Range UV-to-Visible Excitation of Near-Infrared Emission and Slow Magnetic Relaxation in Ln <sup>III</sup> (4,4′-Azopyridine-1,1′-dioxide)[Co <sup>III</sup> (CN) <sub/>6</sub> ] <sup>3–</sup> Layered Frameworks
摘要： Trivalent lanthanide ions combined with two linkers, organic 4,4′-azopyridine-1,1′-dioxide (apdo), and inorganic hexacyanidocobaltate(III), gave a series of magnetoluminescent coordination polymers, [{LnIII(apdo)(H2O)4}{CoIII(CN)6}]·2H2O (Ln = Nd, 1; Tb, 2; Dy, 3; Er, 4; Tm, 5; Yb, 6). They are hybrid organic?inorganic layered frameworks composed of cyanido-bridged {Ln2(μ-NC)4Co2} squares linked by Ln?apdo?Ln bridges into a coordination network of a mixed 4- and 8-metal ring topology. Lanthanide(III) complexes, [LnIII(μ-apdo)2(H2O)4(μ-NC)2]+, of a distorted dodecahedral geometry are isolated by diamagnetic [CoIII(CN)6]3? and apdo linkers. As a result, 1?6 reveal field-induced slow relaxation of magnetization, with typical temperature-dependent relaxation of a single-ion origin for NdIII-containing 1, DyIII-containing 3, and YbIII-containing 6. The related alternate-current magnetic data were precisely analyzed, indicating the multiple magnetic relaxation pathways, including a direct process, strong quantum tunneling of magnetization, non-negligible Raman processes, and crucial two-phonon Orbach thermal relaxation. The thermal energy barriers of the Orbach process, ΔE/kB, are 15.1(9) K with τ0 = 9.8(9) × 10?6 s at Hdc = 4500 Oe, 16.1(8) K with τ0 = 9.0(9) × 10?5 s at Hdc = 1500 Oe, and 17.3(6) K with τ0 = 3.2(7) × 10?6 s at Hdc = 700 Oe, for 1, 3, and 6, respectively, proving the single-molecule magnet (SMM) behavior. Because of the presence of [Co(CN)6]3?, 1?6 show strong UV absorption, while the chromophoric apdo leads to the strong absorption in the visible range. As a result, the visible 4f/3d metal-centered emission is quenched, but the near-infrared luminescence from NdIII and YbIII is observed in 1 and 6, respectively. It is realized by Co-to-Ln metal-to-metal, and apdo-to-Ln ligand-to-metal energy transfers; thus, broad UV-to-visible excitation can be explored. Compounds 1?6 form a novel family of functional bimetallic assemblies, incorporating NIR-emissive SMMs as presented for NdCo (1) and YbCo (6) derivatives.
关键词： single-molecule magnets,near-infrared luminescence,coordination polymers,magnetoluminescent,lanthanide
更新于2025-09-04 15:30:14