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Up-Converting Lanthanide Fluoride Core@Shell Nanorods for Luminescent Thermometry in the First and Second Biological Windows - β-NaYF4: Yb3+, Er3+@SiO2 Temperature Sensor
摘要： Up-converting core@shell type β-NaYF4:Yb3+-Er3+@SiO2 nanorods have been obtained by a two-step synthesis process, which encompasses hydrothermal and microemulsion routes. The synthesized nanomaterial forms stable aqueous colloids and exhibits a bright dual-center emission (λex= 975 nm), i.e. up-conversion luminescence of Er3+ and down-shifting emission of Yb3+, located in the first (I-BW) and the second (II-BW) biological windows of the spectral range. The intensity ratios of the emission bands of Er3+ and Yb3+ observed in the Vis-NIR range monotonously change with temperature, i.e. the thermalized Er3+ levels (2H11/2→4I15/2/4S3/2→4I15/2) and the non-thermally coupled Yb3+/Er3+ levels (2F5/2→2F7/2/4I9/2→4I15/2 or 4F9/2→4I15/2). Hence, their thermal evolutions have been correlated with temperature using the Boltzmann type distribution and 2-th order polynomial fits for temperature sensing purposes, i.e. Er3+ 525/545 nm (max Sr = 1.31 %K-1) and Yb3+/Er3+ 1010/810 nm (1.64 %K-1) or 1010/660 nm (0.96 %K-1). Additionally, a fresh chicken breast was used as a tissue imitation in the performed ex vivo experiment, showing the advantage of the use of NIR Yb3+/Er3+ bands, vs. the typically used Er3+ 525/545 nm band ratio, i.e. better penetration of the luminescence signal through the tissue in the I-BW and II-BW. Such nanomaterials can be utilized as accurate and effective, broad-range Vis-NIR optical, contactless sensors of temperature.
关键词： Up-conversion luminescence,Luminescence intensity ratio (LIR),Functional nanomaterials,Rare earth ions,Energy transfer,Optical thermometer
更新于2025-11-25 10:30:42
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A through-bond energy transfer-based ratiometric fluorescent pH probe: For extreme acidity and extreme alkaline detection with large emission shifts
摘要： A ratiometric fluorescence pH probe 1 based on through-bond energy transfer (TBET) with a 2-(2-hydroxyphenyl)benzoxazole (HBO) as donor and a Rhodamine derivative as acceptor is developed through simple condensation reaction. The probe exhibits a ratiometric fluorescence emission (I593/I422) characteristics and linear response to extreme acidity range of 5.00-2.88, and a ratiometric fluorescence emission (I555/I422) characteristics and linear response to extreme alkaline range of 10.00-13.78, respectively. Moreover, 1 possesses highly selective response to pH over metal ions, good reversibility and excellent photostability. Probe 1 is cellpermeable and can distinguish near pH 5.55 fluctuations in Hela cells. Furthermore, 1 can be immobilized on a test paper, which shows a rapid and reversible colorimetric response to HCl/NH3 vapor by the naked-eye.
关键词： ratiometric fluorescent response,pH sensing,large emission shifts,through-bond energy transfer,fluorescent probe
更新于2025-11-21 11:24:58
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Light Controlled In Vitro Gene Delivery Using Polymer-Tethered Spiropyran as a Photoswitchable Photosensitizer
摘要： A gene delivery system using spiropyran as a photoswitchable photosensitizer for controlled photochemical internalization effect was developed by engineering the outer coating of polyethylenimine/DNA complex with a small amount of spiropyran-containing cationic copolymers. The successful binding of cationic polymers by the polyethylenimine coating was detected by the distance-sensitive fluorescence resonance energy transfer technique that evidenced occurrence of energy transfer between fluorescein-labeled cationic copolymers and polyethylenimine-condensed rhodamine-labeled DNA. The ternary polyplexes feature reversible controllability of singlet oxygen generation based on the dual effect of spiropyrans in photochromism and aggregation-induced enhanced photosensitization, allowing significant light-induced amplification of bPEI-mediated in vitro transgene efficiency (from original 15% to final 91%) at a low DNA dose, with the integrity of supercoiled DNA structure unaffected. The use of spiropyran without the need of other photosensitizers circumvents the issue of uncontrolled long-lasting photocytotoxicity in gene delivery.
关键词： gene delivery,spiropyran,photoswitching,singlet oxygen,fluorescence resonance energy transfer
更新于2025-11-21 11:08:12
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Synthesis, energy transfer and multicolor luminescent property of Eu3+-doped LiCa2Mg2V3O12 phosphors for warm white light-emitting diodes
摘要： In this study, Eu3+-doped LiCa2Mg2V3O12 (LCMVO) phosphors with multicolor luminescent property were prepared by the solid phase reaction. Their structure, morphology and luminescent property were studied systematically by X-ray diffraction, scanning electron microscope and photoluminescence spectra. The LCMVO phosphors showed pure cubic crystal structure with space group (3Ia d ) and irregular spherical morphology. The excitation spectra showed a strong absorption to ultraviolet light. Under the excitation wavelength at 360 nm, they exhibited a cyan emission with a luminescence center at 520 nm. When Eu3+ ions were doped into LCMVO system, the Eu3+ characteristic emissions were also observed and the emission colors were tuned from cyan to orange via adjusting Eu3+ ion concentration. Further, electric dipole-quadrupole interaction and luminescence decay curves were adopted to explain the energy transfer from (VO4)3- to Eu3+. The emission spectra of as-obtained phosphors at different temperature were measured to evaluate their thermal stability. The quantum efficiency values were measured to be 42.5% for LCMVO host and 38.6% for LCMVO: 0.01Eu3+ sample. The final prepared LED lamp showed easeful warm white light with suitable Ra of 89 and CCT of 3847 K, respectively. These results suggest LCMVO phosphors may be applied in near ultraviolet chip-excited white light-emitting diodes.
关键词： energy transfer,multicolor luminescent,self-activated luminescence,excitation and emission spectra,vanadate phosphor,UV-LED
更新于2025-11-20 15:33:11
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Utilization of Ternary Europium Complex for Organic Electroluminescent Devices and as a Sensitizer to Improve Electroluminescence of Red-Emitting Iridium Complex
摘要： Two new lanthanide complexes [Ln(hfaa)3(Py-Im)] [hfaa = hexafluoroacetylacetone, Py-Im = 2-(2-pyridyl)benzimidazole and Ln = Eu(III) (1) and Tb(III) (2)] were synthesized and characterized. An X-ray crystal structure determination confirms that complex 1 is eight-coordinate with a distorted trigonal dodecahedral geometry. It shows typical vivid red Eu(III) emission in the solid state, in solution, and in a polymer matrix. The observed lifetime (τobs) of complex 1 in the solid state, in dichloromethane (DCM) solution, and in thin films is 833.01, 837.95, and 626.16?715.69 μs, respectively, with a photoluminescence quantum yield QEuL ≈ 33% in DCM solution. Complex 2 displays a yellowish-green emission in the solid state (τobs ≈ 36.99 μs), while a near white-light emission in solution (x; 0.2574: y; 0.3371) and in thin films. Therefore, it is a potential candidate for generating single-component white light-emitting materials for solid-state lighting applications. The kinetic scheme for modeling energy-transfer processes shows that the main donor state for 1 is the ligand triplet state (T1) and that energy transfer occurs to both the 5D1 (56.55%) and 5D0 (40.58%) levels. We fabricated a series of single- and double-layer organic light-emitting devices using complex 1. The luminance of the optimized double-layer electroluminescence (EL) device was 373 cd/m2 with very low turn-on voltage of ～4.2 V. Complex 1 was further utilized as a sensitizer to improve the EL of a red-emitting iridium complex PQ2Ir(dpm) (PQ = phenylquinoly-N,C2′, dpm = dipivaloylmethane). The codoped device achieved a maximum brightness and maximum current efficiency (ηc) of 93 224 cd/m2 and 36.38 cd/A, respectively.
关键词： electroluminescence,organic light-emitting devices,photoluminescence,energy transfer,lanthanide complexes
更新于2025-11-20 15:33:11
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Energy transfer behaviors and tunable luminescence in Tb3+/Eu3+ codoped oxyfluoride glass ceramics containing cubic/hexagonal NaYF4 nanocrystals
摘要： For glass ceramics, glass crystallization and doping activators into nanocrystalline phases are the key factors determining optical performance, including energy transfer (ET) process. Herein, we propose a strategy to verify ET behaviors based on glass crystallization, elaborately selecting phase-transformed NaYF4: Tb3+, Eu3+ nanocrystals embedded transparent glass ceramics as a typical example. The ET behaviors from Tb3+ to Eu3+ are clarified via photoluminescence spectra, time-resolved spectra and decay curves. Impressively, the corresponding ET process in cubic NaYF4 turns out to be more efficient than that in hexagonal, in spite of a disorder-to-order transformation from cubic to hexagonal. The reason for this abnormal ET efficiency is that dopants prefer to be partitioned into the cubic NaYF4 rather than the hexagonal one during glass crystallization. This work provides keen insights into the relationship between glass crystallization and ET behaviors, which can also feed back to helpfully guide the design and fabrication of glass ceramics with superior optical performance.
关键词： glass crystallization,cubic/hexagonal NaYF4,energy transfer
更新于2025-11-20 15:33:11
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Single-Composition White Light Emission from Dy3+ Doped Sr2CaWO6
摘要： A series of Dy3+ ion doped Sr2CaWO6 phosphors with double perovskite structure were synthesized by traditional high temperature solid-state method. It was found that there is significant energy transfer between Dy3+ and the host lattice, and the intensities of emission peaks at 449 nm (blue), 499 nm (cyan), 599 nm (orange), 670 nm (red), and 766 nm (infra-red) can be changed by adjusting the concentration of dopant amount of Dy3+ ion in Sr2CaWO6. The correlated color temperature of Dy3+ ion doped Sr2CaWO6 phosphors can be tuned by adjusting the concentration of Dy3+ ion. Upon optimal doping at 1.00 mol% Dy3+, white light with chromaticity coordinate (0.34, 0.33) was emitted under excitation at 310 nm. Thus, single composition white emission is realized in Dy3+ doped Sr2CaWO6.
关键词： double perovskite,energy transfer,white light-emitting,photoluminescence
更新于2025-11-20 15:33:11
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Energy transfer in and fluorescence studies of the Eu-Tb doped BPA-phen system
摘要： To enhance the red emission efficiency of Eu3+ complexes, [Eu/Tbx(BPA)3phen] (BPA = bisphenol A, phen = 1,10-phenanthroline) is designed and synthesized. The complexes are characterized fully and their luminescence properties are evaluated. Co-fluorescence is detected in the Eu/Tbx(BPA)3phen complexes, and the existence of Tb3+ enhances the luminescence intensity of the central Eu3+ because of the intramolecular energy transfer from the 5D4 level of Tb3+ to the 5D0 level of Eu3+. The luminescence intensity of europium ions at 615 nm is the highest for Eu/Tb1(BPA)3phen. To improve the thermal stabilities and mechanical properties of pure complexes, Eu/Tb1(BPA)3phen/PAN (PAN = polyacrylonitrile) is used to fabricate fibres by electrospinning. Compared with Eu/Tb1(BPA)3phen (τ = 1.1087 ms), the fibres have a longer fluorescence lifetime of 1.533 ms. The fibres also retain a high quantum yield of 47.16%. Thus, the flexible luminescent fibres have potential applications in many fields.
关键词： electrospinning,Bisphenol A,energy transfer,luminescence
更新于2025-11-20 15:33:11
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Broad-Spectrum Tunable Photoluminescent Material Based on Cascade Fluorescence Resonance Energy Transfer between Three Fluorophores Encapsulated within the Self-Assembled Surfactant Systems
摘要： A broad spectrum tunable photoluminescent material with dual encryption based on a two-step Fluorescence Resonance Energy Transfer (FRET) between Pyrene (Py), Coumarin480 (Cou480) and Rhodamine6G (R6G) in micelles of SDS and bmimDS is presented. The phenomenon is achievable due to the encapsulation of the fluorophores within these micelles. The transfer of energy as FRET between the pair Py and Cou480 showed ON at 336 nm and OFF at 402 nm in contrast to the FRET observed between the pair Cou480 and R6G that showed ON at 402nm and OFF at 336 nm. However, the transfer of energy as FRET occurs from Py to R6G in the presence of Cou480 when excited at 336 nm, thereby making it a chain of three fluorophores with Cou480 acting as a relay fluorophore receiving energy from Py and transferring it to R6G. The different FRET scenarios between the three fluorophores in micelles provide a window for the generation of a matrix of colors, which occupies a significant 2D area in the chromaticity diagram, having potential applications in security printing. The different fluorophoric ratios generate different colors based on their individual photonic emissions and the FRET processes taking place between them. Writing tests were carried out using varied ratios of the fluorophores in the micellar systems producing different colored outputs under the UV light with insignificant visibility under the white light. We envision that this as-discovered three fluorophoric FRET system could form the basis for the future development of multi-FRET light-harvesting devices and anti-counterfeiting security inks based on much simpler non-covalent interaction aided encapsulation of the fluorophores within the self-assembled soft systems.
关键词： micelles,security printing,Rhodamine6G (R6G),SDS,Pyrene (Py),Coumarin480 (Cou480),bmimDS,Fluorescence Resonance Energy Transfer (FRET),photoluminescent material
更新于2025-11-19 16:46:39
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Electrical and optical properties of organic light-emitting diodes with rhenium(I) complexes using DC and AC methods
摘要： Four rhenium(I) tricarbonyl complexes with 1,10-phenanthroline and derivative bearing electron-donating CH3 and OCH3 substituents were doped into host material poly (9-vinylcarbazole) (PVK) with a mass ratio of 8% as the emissive layer in organic light-emitting diodes (OLEDs). All complexes showed photoluminescence in the solution and embedded into a PVK matrix (λmax～520–550 nm). The comparison with the bare PVK emission and the compound/PVK ?lm shows that the emission of the polymer was quenched through an energy transfer process from PVK to the dopant. The electrical properties of the devices with FTO/PEDOT:PSS/Complex:PVK/Al architecture were investigated using the DC method by curves of current density-voltage and the AC method as admittance spectroscopy, which showed that the behavior of the devices is controlled by charge carrier injection rather than bulk transport.
关键词： Energy transfer,Re(I) complexes,Charge injection,Admittance spectroscopy,Emission,OLEDs
更新于2025-11-14 17:28:48