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Quantitative Sensitization Efficiencies in NIR-Emissive Homoleptic Ln(III) Complexes Using 2-(5-Methylpyridin-2-yl)-8-hydroxyquinoline
摘要： A series of lanthanide complexes [Ln(MPQ)3] (Ln = Nd, Gd, Er, Yb, Lu) using a monoanionic tridentate methylpyridyl-substituted 8-hydroxyquinoline ligand (MPHQ = 2-(5-methylpyridin-2-yl)-8-hydroxyquinoline) have been prepared and characterized using elemental analysis (CHN), single-crystal X-ray diffraction (XRD), and 1H NMR spectroscopy. This ligand forms homoleptic charge-neutral lanthanide complexes with three coordinated ligands arranged in an 'up?up?down' fashion around the metal center. The photophysical properties of the Nd, Er, and Yb complexes were investigated using absorption and emission spectroscopy, with the latter species displaying efficient sensitization in the Near Infra-Red (NIR) region and a photoluminescence quantum yield (PLQY) as high as 1.0% in CH2Cl2 solution. The intersystem crossing and energy-transfer processes involved in the antenna effect were further investigated using transient absorption techniques, which revealed essentially quantitative sensitization efficiencies for the NIR-emitting cations.
关键词： lanthanide complexes,8-hydroxyquinoline ligand,homoleptic,quantitative sensitization efficiencies,NIR-emissive
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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Modulation of the properties of dinuclear lanthanide complexes through utilizing different ?2-diketonate co-ligands: near-infrared luminescence and magnetization dynamics
摘要： A family of new dinuclear lanthanide complexes as the simplest entities showing intramolecular magnetic interactions, [Ln2(dbm)2(L)2(CH3OH)2] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Yb (5), Lu (6)), [Ln2(acac)2(L)2(EtOH)2] (Ln = Dy (7), Er (8)), [Dy2(TTA)2(L)2(CH3OH)2]·2CH2Cl2 (9) and [Dy2(tfa)2(L)2(CH3OH)2] (10) (H2L = N’-(2-hydroxy-5-methylphenyl)-pyrazine-2-carbohydrazide, Hdbm = 1,3-diphenyl-1,3-propanedione, Hacac = acetylacetone, HTTA = 2-thenoyltrifluoroacetone, Htfa = trifluoroacetylacetone), were constructed successfully by the reaction of a Schiff base ligand H2L and four different β-diketonate salts. As for complexes 4, 5 and 8, all exhibit the characteristic emission peaks of the corresponding Er3+, Yb3+ and Er3+ ions, respectively. Meanwhile, the excitation wavelength (510 nm) of 5 is located in the visible region, confirming its significant potential application value. Magnetic studies indicate that complexes 9 and 10 exhibit characteristic slow relaxation of magnetization with the energy barriers (Ueff) of 102 K for 9 and 140 K for 10 under a zero dc field. Under the optimized dc fields, slow magnetic relaxations are present in 2 and 7, and the Ueff values of 9 and 10 have been improved. This proves that the β-diketonate co-ligands deserve an important role in regulating Dy-SMMs influenced by the diverse perturbations of the axial crystal field originating from minor changes in the coordination environment.
关键词： single-molecule magnets,dinuclear lanthanide complexes,β-diketonate co-ligands,near-infrared luminescence,magnetization dynamics
更新于2025-09-23 15:19:57
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Structural, Photophysical and Magnetic Studies of {Ln2} Assembled about Oxime
摘要： A series of bifunctional [Hpy]2[Ln2(NO3)2(ampy)4(H2shi)2] ({Ln2}; Ln = Eu(1), Gd(2) and Dy(3); H3shi = salicylhydroxamic acid; Hampy = 5-aminopyridine-2-carboxylic acid) have been synthesized and characterized. Single-crystal X-ray diffraction analyses reveal that complexes 1 and 3 are isostructural. The complexes {Ln2} exhibit either photophysical or magnetic properties in respect to the central lanthanide ion. It is rarely observed that 1 gives bright and red emission with high quantum yield (16%) and a long luminescence lifetime (547 μs). Magnetic measurement reveals that 3 exhibits significant single molecule magnet behavior with an effective energy barrier of 31 K.
关键词： single-molecule magnet,fluorescence,dinuclear,lanthanide
更新于2025-09-23 15:19:57
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Engineering efficient upconverting nanothermometers using Eu <sup>3+</sup> ions
摘要： Upconversion nanothermometry combines the possibility of optically sensing temperatures in very small areas, such as microfluidic channels or on microelectronic chips, with a simple detection setup in the visible spectral range and reduced heat transfer after near-infrared (NIR) excitation. We propose a ratiometric strategy based on Eu3+ ion luminescence activated through upconversion processes. Yb3+ ions act as a sensitizer in the NIR region (980 nm), and energy is transferred to Tm3+ ions that in turn excite Eu3+ ions whose luminescence is shown to be thermally sensitive. Tridoped SrF2:Yb3+,Tm3+,Eu3+ nanoparticles (average size of 17 nm) show a relative thermal sensitivity of 1.1% K-1 at 25.0 °C, in the range of the best ones reported to date for Ln3+-based nanothermometers based on upconversion emission. The present nanoparticle design allows us to exploit upconversion of lanthanide ions that otherwise cannot be directly excited upon NIR excitation and that may provide operational wavelengths with a highly stable read out to fill the spectral gaps currently existing in upconversion-based nanothermometry.
关键词： nanothermometry,nanoparticles,upconversion,ratiometric strategy,lanthanide ions,Eu3+
更新于2025-09-19 17:15:36
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Orthogonal Shortwave Infrared Emission Based on Rare Earth Nanoparticles for Interference-free Logical Code and Bio-imaging
摘要： Shortwave infrared (SWIR) photoluminescence has received intense interest in many fields in the recent years thanks to the advantages of its wide wavelength, high tissue imaging ability and it is invisible to the naked eye. However, achieving orthogonal SWIR emission still remains challenge. In the present study, synthesized NaErF4@NaLuF4 (Er@Lu) and NaYF4:Nd@NaLuF4 (Y:Nd@Lu) nanoparticles emitted atom-liked SWIR emission, respectively, and the separated distance between the SWIR emission was beyond 50 nm, which permitted orthogonal SWIR signal acquirement with optical filters. Furthermore, we designed an invisible logical code by manipulating the orthogonal SWIR emission of the lanthanide fluoride nanoparticles, which was further operated by basic logical operations and applied in information encryption and anti-counterfeit. In addition, the emission between these two hydrophilic nanoparticles could be also separated in vivo without signals interference and the orthogonal SWIR imaging mode was achieved, which was demonstrated in bio-imaging experiment in vivo. This demonstration extended the orthogonal SWIR emission capacity by controlling the orthogonal emission, opening new opportunities in the data security, diseases diagnosis and non-interference label in vivo.
关键词： bio-imaging,anti-counterfeit,Orthogonal shortwave infrared,SWIR logical codes,lanthanide fluoride nanoparticles
更新于2025-09-19 17:15:36
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Energy Transfer Networks Within Upconverting Nanoparticles Are Complex Systems With Collective, Robust, and History-Dependent Dynamics
摘要： Applications of photon upconverting nanoparticles (UCNPs) in biological imaging and solar energy conversion demand that their anti-Stokes luminescence be both tunable and efficient. Rational design of more efficient UCNPs requires an understanding of energy transfer (ET) between their lanthanide dopants – dynamics that are typically characterized by measuring luminescence lifetimes. Existing knowledge, however, cannot explain basic observations in lifetime experiments such as their dependence on excitation power, significantly limiting the generality and reliability of lifetime measurements. Here, we elucidate the origins of the ET dynamics and luminescence lifetimes of Yb3+,Er3+-codoped NaYF4 UCNPs using time-resolved luminescence and novel applications of rate equations and stochastic simulations. Experiments and calculations consistently show that, at high concentrations of Er3+, the luminescence lifetimes of UCNPs decrease as much as 6-fold when excitation power densities are increased over six orders of magnitude. Since power-dependent lifetimes cannot be explained by intrinsic relaxation rates of individual transitions, we analyze lifetime data by treating each UCNP as a complex ET network. We find that UCNP ET networks exhibit four distinguishing characteristics of complex systems: collectivity, nonlinear feedback, robustness, and history dependence. We conclude that power-dependent lifetimes are the consequence of thousands of minor relaxation pathways that act collectively to depopulate and repopulate Er3+ emitting levels. These ET pathways are dependent on past excitation power because they originate from excited donors and excited acceptors; however, each transition has an unexpectedly small impact on lifetimes due to negative feedback in the network. This robustness is determined by systematically 'knocking out,' or disabling, ET transitions in kinetic models. Our classification of UCNP ET networks as complex systems explains why UCNP luminescence lifetimes do not match the intrinsic lifetimes of emitting states. In the future, UCNP networks may be engineered to rival the complexity of biological networks that pattern features with unmatched precision.
关键词： complex systems,energy transfer,upconverting nanoparticles,lanthanide dopants,power dependence,luminescence lifetimes
更新于2025-09-19 17:15:36
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Electronic structure and optical properties of Ln(III) nitrate adducts with 1,10-phenanthroline
摘要： Adducts of tris-nitrates of rare-earth elements Ce(III), Nd(III), Eu(III), and Er(III) with two molecules of 1,10-phenanthroline with formula Ln(NO3)3(Phen)2 are studied by X-ray photoelectron spectroscopy (XPS) and quantum chemistry (DFT/TDDFT). The geometric structure for DFT modeling is build using X-ray diffraction data. To analyze the composition and differences of the electronic structure in the series under study, XPS spectra were obtained for which interpretation was performed using calculated data. It has been shown that the molecule of Phen, when attached to the complexes of nitrates, is polarized, leads to an increase in absorption in the visible region and reduces the energy gap between HOMO and LUMO. Experimental absorption spectra were obtained, described and interpreted using TDDFT simulation. The transitions in adducts from π to π * MO in Phen ligands determine the main absorption band. The reasons for the absence of luminescence in adducts with ions Ce(III), Nd(III), and Er(III) are revealed by the example of the correlation diagram of singlet and triplet levels. A possible origin of coloring of adducts is determined using TDDFT.
关键词： Optical properties,Nitrates,DFT,Lanthanide ions,Photoelectron spectroscopy
更新于2025-09-19 17:15:36
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Identification and optical features of the Pb4Ln2O7 series (Ln = La, Gd, Sm, Nd), genuine 2D-van der Waals oxides.
摘要： We report on the identification and survey of the Pb4Ln2O7 series (Ln= La, Gd, Sm and Nd) which turn out to be real Van der Waals 2D oxides. In the neutral layers, strong covalent Pb-O bonds together with external stereoactive Pb2+ lonepairs, which play as sensitizers, lead to an ideal matrix for enhanced and tunable luminescence by lantanide emittors, tested here for Sm3+ and Eu3+ doping. DFT calculations and preliminary exsolution experiments validate the weak bonding between the layers separated by 3.5 ? and suggest a undirect to direct crossover realized by isolating the layers.
关键词： lanthanide doping,luminescence,2D materials,Van der Waals oxides,DFT calculations
更新于2025-09-19 17:15:36
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A series of two-dimensional lanthanide coordination polymers: synthesis, structures, magnetism and selective luminescence detection for heavy metal ions and toxic solvents
摘要： A series of two-dimensional lanthanide coordination polymers: synthesis, structures, magnetism and selective luminescence detection for heavy metal ions and toxic solvents
关键词： lanthanide ions,coordination polymers,luminescence properties,crystal structure,magnetic properties
更新于2025-09-19 17:15:36