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To address the problem of cyan-green light deficiency in fluorescent converters for laser diode (LD) illumination applications, Ca 3-x Sc 2 Si 3 O 12 :xCe3+ (CSS:xCe3+) cyan-green fluorescent ceramics and CSS:Ce3+ phosphor in glass (CSS:Ce3+-PiG) fluorescent converter were successfully prepared. Among them, the CSS:0.08Ce3+ cyan-green fluorescent ceramic and 20 wt% CSS:Ce3+-PiG fluorescent converter had the highest luminescence intensity. At 450 nm excitation, the emission spectra of both materials showed an asymmetric broadband band between 470 nm and 690 nm. And the two fluorescent converters are not appear of luminescence temperature quenching until more than 538 K. The performance of the white LDs synthesized with ceramic and PiG converters was investigated. Under different power excitation, the green emission intensity of both wLD is enhanced with increased incident laser power. The wLDs based on CSS:Ce3+ fluorescent ceramics have a luminous flux of 880 l m and the maximum luminescence efficiency of 176 l m/W at an incident power of 5 W. And the wLDs of PiG fluorescent converters have a maximum luminous flux of 584 l m and luminescence efficiencies of up to 117 l m/W. CSS:Ce3+ ceramics and CSS:Ce3+-PiG are green fluorescent converter with good luminescence performance and thermal stability. It will play an important role in the compensation of the cyan light in LD illumination. [ABSTRACT FROM AUTHOR]

In recent times, there has been significant interest in Mn4+-activated red phosphors in double perovskite oxide materials. However, the practical use of these materials is hindered by concerns related to their thermal and humidity stability. In this research, we have synthesized deep red-emitting phosphors with the composition La 2 LiNb (1- x) O 6 : x Mn4+ using a conventional high-temperature solid-phase method. The microstructures and luminescence properties of these phosphors have been thoroughly investigated. All the samples consist of irregular microcrystals with an average size ranging from 3 to 7 μm, and they exhibit excellent phase purity and crystallinity. Under excitation by 335 nm ultraviolet light, the La 2 LiNb (1- x) O 6 : x Mn4+ phosphors emit a narrow and sharp red band (centered at ∼710 nm), and the emission intensity initially increases and then decreases with increasing Mn4+-doping concentration, peaking at x = 0.5%. The La 2 LiNb 0.995 O 6 : 0.5%Mn4+ phosphor exhibits exceptional thermal stability, with a normalized emission intensity of 66.24% maintained at 150 °C. More importantly, the La 2 LiNb 0.995 O 6 :0.5%Mn4+ phosphor exhibits excellent humidity stability and can maintain more than 90% of its initial emission intensity after immersion in deionized water for 24 h. The La 2 LiNb 0.995 O 6 : 0.5%Mn4+ phosphor demonstrates an impressive resistance to humidity-induced luminescence quenching. It maintains a significantly higher far-red emission intensity at relative humidities exceeding 65%. These newly developed La 2 LiNb (1- x) O 6 : x Mn4+ phosphors hold great potential as red phosphors for high-power plant growth LEDs in extended outdoor, high-humidity conditions. [ABSTRACT FROM AUTHOR]

X-ray luminescent nanoparticles have gained significant attention as promising tools for implementing multimodal imaging and radiation-based treatments in theragnostics. The intricate comprehension of their properties and the underlying mechanisms driving the conversion of X-rays into light is critical for their success in various applications. LaPO 4 nanoparticles doped with various individual luminescence centers, gadolinium (Gd3+), europium (Eu3+), dysprosium (Dy3+), and terbium (Tb3+), were produced via co-precipitation and investigated for their behavior upon X-ray excitation using energies of up to 225 kV. These materials evidenced a radioluminescent response dependent on the dopant concentrations, with emission lines from 300 to 700 nm, providing insights into the luminescence quenching effect in these structures. The luminescent characteristics of the nanoparticles were studied under continuous irradiation, evidencing the materials' ability to withstand high absorbed doses and preserve their properties. Furthermore, the influence of dopant concentrations on crystallite size and the dependence of luminescence on thermal treatments was investigated. The assessment of nanoparticle stability in aqueous suspension was evaluated over a broad pH range, revealing a tendency of the LaPO 4 surface to selectively interact with electropositive species. This insight enhances our comprehension of the colloidal stability of the material, positioning it for extended applications and in vitro evaluations, along with further surface functionalization. [ABSTRACT FROM AUTHOR]

Phosphor-converted white light emitting diodes (pc-WLEDs) as a new green lighting source have attracted considerable attention around the world. Single-component white light emitters are particularly attractive for fabricating economical solid-state devices for display and lighting. However, the emission loss of phosphors caused by thermal quenching is one of the important factors limiting its application. Herein, a series of single-phase Li 3 Ba 2 Y 3 (WO 4) 8 :Dy3+,Tm3+ phosphors were synthesized by solid state reaction. The crystal structure, electronic structure, morphology, temperature dependent photoluminescence and decay lifetimes were systematically studied by experimental and theoretical calculations. Under the UV excitation, the phosphor could easily emit yellow, blue and white light by simply tuning the ratio of Dy3+ to Tm3+ ions. Notably, the obtained phosphors showed an anti-thermal quenching at 422 K, and the luminous intensity remained 93.09 % of that at room temperature even up to 472 K. Moreover, the CIE chromaticity coordinates hardly changed with the increase of temperature. Ultimately, by combining the phosphor with a 365 nm NUV chip, a high-performance pc-WLED device with a correlation color temperature of 4333 K and CIE coordinates of (0.328,0.396) was successfully realized. This work indicates that the designed single-phase Li 3 Ba 2 Y 3 (WO 4) 8 :Dy3+,Tm3+ may be potential candidates for efficient single-phased white emission in pc-WLED lighting applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, the unique 5D 4 energy level of terbium (Tb3+) can contribute to narrow-band green light emission, which has high application prospects. However, due to its poor thermal stability at high temperatures, how to enhance the antithermal-quenching properties of Tb-doped phosphors has become a research difficulty in the field of solid-state lighting and temperature sensing. In this contribution, the antithermal-quenching green-emitting of terbium was achieved by Nb/Ta substitution to form GdNb 1-x Ta x O 4 :Tb3+ phosphors with various components. Photoluminescence analyses reveal an increasing trend in both the optical band gap and the intervalence charge transfer (IVCT) energy level positions with substitution. Variable-temperature spectrums observed that the phosphors under different compositions presented a large discrepancy in thermal quenching performance. It is elucidated that the elevated position of the IVCT energy level (IVCT-EL) predominantly influences thermal quenching, bolstering its role as a compensatory luminescence channel of 5D 3 →5D 4 far more than functioning as a quenching luminescence channel for Tb3+5D 3 /5D 4. Delving into the perspective of IVCT-EL positioning unveils the intrinsic mechanism through which IVCT-EL positions modulate the thermal quenching properties of phosphors with varying compositions due to the substitution of Ta for Nb. This insight facilitates the realization of enhanced thermal quenching resistance in phosphors. Furthermore, the antithermal-quenching property of Tb3+ in single-phase phosphors can be effectively modulated by excitation at different wavelengths. This tuning scheme not only advances the exploration of terbium-doped antithermal-quenching phosphors but also provides a novel strategy and reference for designing green-emitting phosphors in the fields of lighting and sensing. [Display omitted] [ABSTRACT FROM AUTHOR]

Fluoroborates have garnered significant research interest due to their intricate structure and unique nonlinear optical properties. In this work, pure and Eu-activated Ba 5 B 4 O 10 F 2 were prepared via the high-temperature solid-state ceramic method. Ba 5 B 4 O 10 F 2 is a wide band semiconductor (E g = 4.51 eV) with an indirect transition characteristic. The optical absorption, photoluminescence, and dynamic spectra of Eu2+/3+ activators were investigated. Luminescence intensities of Eu2+ and Eu3+ had distinctly different responses to doping content. The residual Eu3+ centers in Ba 5-5 x Eu 5 x B 4 O 10 F 2 (x > 0.03) cannot be avoided even it was sintered in a reducing atmosphere. Time-resolved spectra and decay curves also confirm the presence of Eu3+ with Eu2+. Under near-UV light excitation, a strong emission band from the 5d→4f transition of Eu2+ was detected overlapping with sharp peaks from (5D 0 →7F 0,1,2,3,4) of Eu3+ in Ba 5-5 x Eu 5 x B 4 O 10 F 2 (x > 0.03). As the Eu-doping level increases, the intensity ratio of Eu2+ and Eu3+ changes regularly, and the luminescent intensity of Eu3+ obviously and systematically becomes stronger. As the temperature changes from 25 °C to 150 °C, the luminescent intensity of Eu3+ increases, while that of Eu2+ gradually decreases. The results confirm the energy transfer (ET) from Eu2+ to Eu3+ in Ba 5 B 4 O 10 F 2. Eu3+ can act as killers, leading to the luminescence quenching of Eu2+ activators. The heterovalent substitution of Eu and NaF in Ba 5 B 4 O 10 F 2 not only reduces the content of Eu3+ but also significantly enhances the efficiency of Eu2+. The experiments demonstrate that to improve the luminescence efficiency of Eu2+, it is important to focus on reducing the residual Eu3+ in the lattice through enhancing the reduction from Eu3+ to Eu2+. [ABSTRACT FROM AUTHOR]

The novel red-emitting phosphors Ba 3 Lu 1– x Eu x B 9 O 18 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.85) belonging to the Ba 3 REE B 9 O 18 (REE – Y, Pr–Lu) family were successfully obtained by a multistep solid-phase synthesis. X-ray diffraction experiments revealed no phase transitions caused by the Eu3+ → Lu3+ isomorphic substitution in this series of solid solutions. An increase in the Eu3+ content leads to an expectable increase of hexagonal unit cell parameters and volume. Optical properties of the Ba 3 Lu 1– x Eu x B 9 O 18 (x = 0–0.85) phosphors were investigated. The highest emission intensity was demonstrated by Ba 3 Lu 0.6 Eu 0.4 B 9 O 18. The concentration quenching of luminescence was revealed for the x (Eu3+) > 0.4 samples. Concentration quenching, quantum yield and structural data were compared between three red-emitting Ba–Lu borates-phosphors (BLBO:Eu3+) containing independent crystallographic sites for the REE ions (n = 1–3) in crystal structure. It was revealed that the higher the number of nonequivalent cationic REE sites suitable for the Eu3+ → Lu3+ substitution, the higher the quantum yield taking into account practically equal amount of an optimal concentration of the activator-ion. Such an observation could be useful for a crystal chemical design of novel phosphors. [Display omitted] • Novel red-emitting phosphors Ba 3 LuB 9 O 18 :Eu3+ are synthesized. • Optical properties of the phosphors are studied. • Luminescence and structural data of three Ba–Lu borates-phosphors are compared. • Dependence of quantum yield on number of nonequivalent REE cationic sites is discussed. [ABSTRACT FROM AUTHOR]

So far, overcoming thermal quenching remains a huge challenge in the application of phosphor materials. The intervalence charge transfer (IVCT) state has an inestimable role in the compensation of antithermal-quenching effects and is widely used in the research of applications in optical temperature sensing, yet little study has been reported on its modulation of thermal quenching properties. In this contribution, the thermal quenching properties of praseodymium-activated solid-solution substituted GdNb 1-x Ta x O 4 phosphors were investigated systematically for the inaugural time from the perspective of IVCT energy level positions. According to the empirical formula, the IVCT level positions in the phosphor increase sequentially from 32960.71 cm−1 to 33442.15 cm−1, the DFT calculates the extension of the substrate band gap from 3.6408 eV to 4.3066 eV, and the contributing energy level of the conduction band is determined. The variation in the position of the IVCT energy level explains the alteration of the luminescence intensity at room temperature for different composition phosphor 3P 0 and 1D 2 energy levels. More particularly, it was analyzed that in the variable temperature spectra, x = 0–0.75 exhibited different degrees of efficient antithermal-quenching properties at 303–523 K, while no antithermal-quenching was presented at x = 1. By analyzing the IVCT energy level position and other influencing factors such as band gap, the feasibility of the IVCT energy level position as a competing model for the compensation and quenching channels is established, and the internal mechanism of regulating thermal quenching property is revealed. Effective control of the phosphor resistance to thermal quenching performance was achieved, which directly determines whether enhanced or diminished thermal quenching can be obtained. This finding provides a new effective strategy for the tuning of thermal quenching luminescence of Pr3+-doped Nb/Ta system phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

So far, overcoming thermal quenching remains a huge challenge in the application of phosphor materials. The intervalence charge transfer (IVCT) state has an inestimable role in the compensation of antithermal-quenching effects and is widely used in the research of applications in optical temperature sensing, yet little study has been reported on its modulation of thermal quenching properties. In this contribution, the thermal quenching properties of praseodymium-activated solid-solution substituted GdNb 1-x Ta x O 4 phosphors were investigated systematically for the inaugural time from the perspective of IVCT energy level positions. According to the empirical formula, the IVCT level positions in the phosphor increase sequentially from 32960.71 cm−1 to 33442.15 cm−1, the DFT calculates the extension of the substrate band gap from 3.6408 eV to 4.3066 eV, and the contributing energy level of the conduction band is determined. The variation in the position of the IVCT energy level explains the alteration of the luminescence intensity at room temperature for different composition phosphor 3P 0 and 1D 2 energy levels. More particularly, it was analyzed that in the variable temperature spectra, x = 0–0.75 exhibited different degrees of efficient antithermal-quenching properties at 303–523 K, while no antithermal-quenching was presented at x = 1. By analyzing the IVCT energy level position and other influencing factors such as band gap, the feasibility of the IVCT energy level position as a competing model for the compensation and quenching channels is established, and the internal mechanism of regulating thermal quenching property is revealed. Effective control of the phosphor resistance to thermal quenching performance was achieved, which directly determines whether enhanced or diminished thermal quenching can be obtained. This finding provides a new effective strategy for the tuning of thermal quenching luminescence of Pr3+-doped Nb/Ta system phosphors. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, Fe 3 O 4 /α-Fe 2 O 3 /Y 2 O 3 :Eu3+ multifunctional nanocomposites were synthesized using a hydrothermal method. Fe 3 O 4 /α-Fe 2 O 3 /Y 2 O 3 :Eu3+ nanocomposites are core-shell nanostructures consisting of a superparamagnetic nanomagnetite core, which is converted to hematite during the synthesis. As a theranostic material, hematite could be used in drug-release processes, while nanomagnetite generates heat in a hyperthermia cancer treatment. An outer shell of Y 2 O 3 :Eu3+ nanophosphor is added to give nanocomposites photoluminescent properties and to render them visible in bioimaging. Structural, optical, and magnetic features of nanocompositesare studied using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), Raman, photoluminescence (PL), vibrating-sample magnetometer (VSM), and high-resolution transmission electron microscope (HRTEM) techniques. Photoluminescence properties of nanocomposites show a quenching effect related to the proportion of magnetite and Y 2 O 3 :Eu3+. A luminescence quenching mechanism is proposed based on the optical effects of a core-shell structure. Magnetic saturation grows proportionally with the amount of magnetite present, which indicates that Fe 3 O 4 magnetic structure is not altered, even by the hematite that forms around it. The synthesized nanocomposites possess a core-shell morphology modified by the different proportions of their components. The optical, structural, and magnetic nanocomposite properties found will be of interest in theranostic materials research in the biomedical field. [ABSTRACT FROM AUTHOR]

Photodynamic and photothermal therapy (PDT and PTT) have been widely used in tumor treatment researches owe to its advantages of spatiotemporal controlliability and non-invasiveness. Combining two phototherapy strategies together and/or with chemodynamic therapy (CDT) could achieve better therapeutic efficiency, but the resulting inconvenient dual-laser irradiation and the potential skin toxicity limit its development. Moreover, the lack of tumor-specificity causes side-effects to normal tissues. Therefore, shortening the irradiation time, or integrating two lasers, and increasing tumor specificity are necessary to reduce side effects. Herein, we developed a tumor microenvironment responsive one-laser-excited PDT/PTT/CDT synergistic therapeutic nanosystem ZPPSC (refers to ZGGC-PDA-PEI-Si-Pc-Cu) for precise tumor phototherapy. In this nanosystem, the simultaneous PTT and PDT activation using a single laser, enhancing phototherapy efficiency while reducing phototoxicity were achieved. Specifically, persistent luminescence nanoparticle ZnGa 1.6 Ge 0.2 O 4 :Cr (ZGGC) is coated with polydopamine (PDA) through self-polymerization of dopamine, modified with polyethyleneimine (PEI), Si-Pc, and adsorbed with Cu2+. Cu2+ quenches the persistent luminescence (PersL) in physiological environment, and could be reduced to Cu+ under the excess GSH in tumor cells, resulting in removing from nanosystem. Whereafter, PersL is restored, and Fenton-like reaction between Cu+ and overexpressed H 2 O 2 is triggered to generate ·OH for CDT therapy. Under single 808-nm irradiation, PDA will be irradiated to perform PTT, and the opening persistent luminescence could irradiate photosensitizers for PDT and continues to stimulate them even after the laser stops, reducing external excitation time. The in vivo results shown that ZPPSC exhibit ideal PDT performance, and increased local temperature close to 60 °C. Most importantly, the tumor inhibition rate by combined PTT, PDT, CDT with 5-min 808-nm laser irradiation is 99%, and even one mouse was completely cured with the bearing tumor completely disappeared. By using this nanosystem, PDT and PTT were achieved by only on laser with relatively short irradiation time. Moreover, the weak tissue penetration of the 660-nm PS excitation source was also addressed. Our design achieves tumor-specific one-laser three-mode phototherapy with shortened irradiation time, enhancing therapy effectiveness while minimizing side effects. These results exhibit great therapeutic outcomes of ZPPSC for precious tumor phototherapy. One-laser-excited three-model therapy nanosystem is prepared for tumor specific treatment. Cu2+ realizes tumor-responsive PDT process "turn on" and CDT, PDT and PTT are co-excited by one laser simultaneously. [Display omitted] [ABSTRACT FROM AUTHOR]

Structural and thermal stability are two essential conditions in phosphor research, which are related to the structure of the host and the position of 4T 2 energy lever in Mn4+-activated phosphors. Here, Mn4+-activated CaGdAlO 4 phosphor with superior structural stability was synthesized through systematically screening the aluminate family of ABAlO 4 (A = Mg, Ca, Sr, Ba; B Sc, Lu, Y, Gd, La). Sr2+ was subsequently introduced to modulate the 4T 2 state level of Mn4+ for achieving better thermal stability in CaGdAlO 4 :Sr2+,Mn4+ phosphor. The luminescence quenching temperature T 1/2 show a parabolic trend with the increasing of Sr2+ dopant in Ca 1-y GdAlO 4 :ySr2+, Mn4+ phosphors, and change from 403 K to 426 K and 387 K in CaGdAlO 4 :Mn4+, Ca 0.4 GdAlO 4 :0.6Sr2+,Mn4+ and SrGdAlO 4 :Mn4+ three samples, respectively. The corresponding crystal-field calculations confirm that a certain amount of Sr2+ doping can improve the 4T 2 state of Mn4+ and obtain better thermal stability in the phosphor. All the samples have deep-red emission located at 712 nm, which matches well with the absorption spectra of green vegetables. This deep-red light accelerate morphological formation and increase vegetable biomass. This work is expected to stimulate more exploration of Mn4+-doped oxide phosphors with better structural and thermal stability for emerging applications of agricultural lighting. [ABSTRACT FROM AUTHOR]

Thermal quenching (TQ) that weakens luminescent intensity is crucial for the application value of a phosphor. Here, we report a series of color-tunable phosphors Na 2 MgAl 10 O 17 : x Eu2+ (NMA: x Eu2+) from green to cyan. For optimized Eu2+ concentration of x = 0.15, its internal and external quantum efficiency can reach up to 86% and 43%, respectively. In addition, it is unexpected that NMA:0.15Eu2+ exhibits anti-temperature quenching (TQ) luminescence even up to 300 °C, which is due to the ability of the defect energy levels to counteract the usual loss of emission by TQ through EPR and TL spectral analysis. Then, a prototype w-LED lamp by using NMA:0.15Eu2+ cyan phosphor, CaAlSiN 3 :Eu2+ red phosphor, and 380 nm LED chip is fabricated. This work not only reports a new phosphor with high efficiency and good thermal stability of luminescence, but also brings forward a defect engineering approach for enhancing the thermal quenching resistance of a phosphor. [Display omitted] [ABSTRACT FROM AUTHOR]

Quantum dot light-emitting diodes (QLEDs) are considered as the ideal candidate for next-generation displays, solid-state lighting, and optical communication applications. Although the efficiency of QLEDs has been significantly improved to the level comparable to that of organic light-emitting diodes in recent years, simultaneously achieving high efficiency and high brightness still remains challenging for QLEDs. In this work, we report a facile and effective electron-transport-layer interface control strategy of incorporating 3-aminopropyl triethoxysilane (APTES) into a ZnO nanocrystal-solution to enhance charge injection balance and suppress interfacial exciton quenching via in-situ formation of ZnO/organic silica (hereinafter referred to as ZnO/SiO 2) quasi core/shell nanoparticles in the solution, enabling red QLEDs to exhibit a maximum luminance intensity of 261,700 cd m−2, a peak external quantum efficiency (EQE) of 19.0%, and low efficiency roll-off at high luminance (an EQE up to 16.8% remained at a brightness of 200, 000 cd m−2). Our results demonstrate that substituting quasi core/shell-structured ZnO/SiO 2 nanoparticles for traditional ZnO nanocrystals as electron transport materials is a simple and effective means of fabricating QLEDs with both high efficiency and high luminance, which is expected to facilitate the development of QLED technology toward practical applications in lighting, displays and optical communication. [ABSTRACT FROM AUTHOR]

GdAl 3 (BO 3) 4 :Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72–1985. The FTIR analyses show the detection of B − O stretching and B − O − B bending modes as well as Al − O and Gd − O bonds in the phosphor samples. Energy dispersive spectroscopy (EDS) analysis reveals that Sm, Eu, Dy, and Tb have been successfully doped into GdAl 3 (BO 3) 4. The observed broad intrinsic luminescence band can be caused by oxygen-induced luminescence defects in the GAB host with hydrous precursors. The luminescence properties of rare earth ion-doped GdAl 3 (BO 3) 4 samples are analysed by photoluminescence spectra, showing their optimal doping concentrations and critical distances of Dy3+, Eu3+, Sm3+ and Tb3+ are 2 wt% − 25.8 Å, 7 wt% − 17 Å, 1 wt% − 32.59 Å, and 7 wt% − 17.03 Å. Additionally, the energy transfer mechanism for luminescence quenching was determined as dipole-dipole (for Dy3+, Eu3+, and Tb3+) or dipole-quadrupole (for Sm3+) and the cross-relaxation process. GdAl 3 (BO 3) 4 samples obtained by doping with different RE3+ ions exhibit intense light emissions with different colors originating from different RE3+ ions under 349 nm excitation. When doped with different concentrations of RE3+ ions, the luminescence properties of the samples changed. The synthesized luminescence materials have potential applications in lighting and display technologies. [ABSTRACT FROM AUTHOR]

Herein, we report strategies combining component adjustment and ion doping for the development of photochromic materials with high color-changing contrast. Sr 0.05 Ba 0.95 HfO 3 : Eu3+ ceramics showed reversible photochromism from off-white to dark brown under the alternating action of 254 nm UV light and heat treatment at 300 °C. This is caused by the capture and release of electrons by defects in the Sr 0.05 Ba 0.95 HfO 3 : Eu3+ host such as oxygen vacancies. Under this strategy, the maximum photochromic contrast ratio of 44.81% is achieved, which is a great improvement compared to pure SrHfO 3 (15.91%) and BaHfO 3 (14.98%). The luminescence quenching behavior based on the photochromic reaction can effectively modulate the emission of Eu3+. The reversible photochromic properties of Sr 0.05 Ba 0.95 HfO 3 : Eu3+ ceramics can be used for repeated writing and erasing of optical information, and the significant body color change improves its resolution in pattern information storage. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (QDs) have been considered as excellent luminescent materials that can replace traditional phosphors in backlit display field due to their narrow emission and high photoluminescence quantum yield (PLQY). However, the problems of rapid aging and luminescence quenching seriously affect their practical applications. One of the effective strategies to improve the stability is to prepare the QDs in glass. Herein, highly quality perovskite QDs embedded borosilicate glasses have been successfully prepared with the introduction of alkaline earth metals. With the help of alkaline earth, the further precipitation of perovskite QDs from glass can be promoted and then the heat-treatment temperature and time decreased. The crystallization principle, luminescence performance, and stability are studied in detail. The intrinsic PLQY of the optimal perovskite QDs glass powder exceeds 95%. The perovskite QDs glass powder was mixed with epoxy resin to form a flexible film. Both the QDs glass powder and film could still emit bright light under ultraviolet light when immersed in 90 °C hot water. The color gamut of LED based on QDs glass film reaches 112% of the NTSC standard, 158% of the sRGB standard, showing its strong potential applications in the backlit display field. [ABSTRACT FROM AUTHOR]

A highly efficient luminescent Zn-MOF@COF hybrid has been successfully prepared and employed as specific detection and removal of Cu(II) ions and methylene blue dye in aqueous media with adsorption capability of 99.8 and 97.6 % respectively. [Display omitted] • An interlinked hybrid Zn-MOF@COF based on the Zn-N bond is synthesized. • Zn-MOF@COF shows excellent capability for detection and removal of Cu2+ and methylene blue (MB). • The Zn-MOF@COF detected Cu2+ ions via luminescence quenching with high K sv and low detection limit values. • The maximum adsorption efficiency of Zn-MOF@COF towards Cu2+ and MB is 99.8 and 97.6 % respectively. Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have attained great attraction from researchers nowadays because of their diverse applications owing to their tunable porosity and controllable functions. This work reports an interlinked hybrid composite of Zn-based MOF and imine-base COF (Zn-MOF@COF) based on the Zn N bond. The resulting mesoporous hybrid material shows excellent capability for detecting and removing Cu2+ ions and methylene blue (MB) from water. The adsorption process followed pseudo-first-order kinetics, and the Langmuir model fits for Cu2+ adsorption and the Freundlich isotherm model for MB adsorption. The thermodynamic studies showed that the reaction process between Zn-MOF@COF composite and adsorbates is endothermic. Further, negative ΔS0 show a decrease in randomness and an increase in the order of adsorbent on solid/liquid interface, and positive ΔG0 suggests non-spontaneous behaviour of the reaction process. The composite material detected Cu2+ ions via luminescence quenching with a high K sv value and low detection limit, showing strong interactions with Cu2+. The maximum adsorption efficiency of Zn-MOF@COF towards Cu2+ and MB is 99.8 and 97.6 %, respectively. The hybrid composite shows the best performance for decontaminating Cu2+ ions and MB among various COF- and MOF-based chemosensors. [ABSTRACT FROM AUTHOR]

Reactions of Cd(NO 3) 2 with tri-imidazolyl ligands and 4,4′-biphenyldicarboxylic acid resulted in the formation of 2D-MOF and its selective luminescence sensing were investigated. [Display omitted] • 2D-MOF based on tri-imidazolyl ligands and 4,4′-H 2 bpda were synthesized. • Complex 1 exhibits billayered structure with rectangular channels. • Complex 1 can selectively sense Fe3+ by the luminescence quenching method. A Cd(II) metal–organic framework with 4,4′-biphenyldicarboxylic acid (4,4′-H 2 bpda) and 1,3-bis(1-imidazolyl)-5-[4-(1-imidazolyl)-phenoxymethyl]-benzene (ptim), {[Cd 2 (NO 3) 2 (bpda)(ptim) 2 ]·2DMF·H 2 O} n (1), has been synthesized under hydrothermal condition. Single-crystal X-ray diffraction analyses demonstrate that complex 1 exhibits a 2D bilayered structure interconnected with 4-bpda, resulting in 1D channels. These layers are arranged via the π···π stacking interactions between ptim ligands, forming a 3D supramolecular structure. The solid state luminescent property of 1 at ambient temperature was also investigated and showed a high selectivity and sensitivity for Fe(III) owing to the quenching effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Zr-MOF incorporating amino and sulfoxide dual-functional groups was constructed. • Zr-MOF showed excellent adsorption and detection performances of TCs. • The mechanisms of adsorption and detection were explained and confirmed in detail. Antibiotics contamination in aquatic environment has attracted considerable interest owing to its detrimental effects on human health and ecological safety. Therefore, developing more efficient materials for synchronous removal and detection of antibiotics is highly desired yet challenging. Herein, one novel zirconium-based metal–organic framework (Zr-MOF) was successfully constructed via a tetra-carboxylate ligand (H 4 SBTD-NH 2) and demonstrated as a dual-functional platform for simultaneous removal and detection of tetracycline antibiotics. The ligand featuring amino and sulfoxide functionalization, facilitates the formation of variable pore sizes and a surface adorned with potential acting sites along the channels. Zr-MOF demonstrated high TCs adsorption capabilities (262.46 and 267.92 mg g−1 for TC and OTC, respectively). In addition to its high uptake, Zr-MOF exhibited exceptional sensitivity in the detection of TCs, particularly through the luminescence quenching effect, with remarkably nanomolar detection limits for TC (LOD 6.14 nM), and OTC (LOD 14.59 nM). These values are comparable to, or even exceed, the other excellent-performing MOF-based materials designed for removing and detecting of TCs. The outstanding performance of Zr-MOF should stem from a synergistic interplay of electron transfer, the inner filter effect (IFE), and specific host–guest interactions. The possible theoretical mechanism was investigated and discussed in detail by DFT calculations. This work provides a design basis for the development of materials that can both detect and remove specific pollutants from wastewater. [ABSTRACT FROM AUTHOR]

Discovering bismuth based smart materials that can respond to thermal, mechanical, and wide range X-ray to infrared photon excitation remains a challenge. Such materials have various uses like in advanced information encryption. In this work, valence state change between Bi2+, Bi3+, and Bi4+, and the dual role of Bi3+ in trapping electrons and holes have been studied in Bi3+ or/and Ln3+ (Ln=Tb or Pr) doped LiScGeO 4 family of compounds by vacuum referred binding energy (VRBE) diagram construction, thermoluminescence, and spectroscopy. Electron release from Bi2+ has been evidenced. It can be used to experimentally determine the VRBE in the Bi2+ 2P 1/2 ground state and to realize Bi3+ negative quenching luminescence. Particularly, a new force induced charge carrier storage phenomenon has been discovered for non-real-time force recording. Wide range of emission tailorable afterglow, unique Bi3+ ultraviolet-A, white, and infrared afterglow have been demonstrated by using Bi3+ as a hole trapping and recombination center and using energy transfer processes from Bi3+ to Tb3+, Pr3+, Dy3+, or Cr3+. Proof-of-concept advanced anti-counterfeiting, information encryption, and X-ray imaging will be demonstrated. This work not only develops smart storage phosphors, but more importantly unravels the valence change between Bi2+, Bi3+, or Bi4+ and how it can affect the trapping and release of charge carriers with thermal, optical, or mechanical excitation. This work therefore can promote the discovery and development of Bi3+ based smart materials for various applications. Discovering bismuth based smart materials that can respond to thermal, mechanical, and wide range X-ray to infrared photon excitation remains a challenge. Such materials have various uses like in advanced information encryption. In this work, valence state change between Bi2+, Bi3+, and Bi4+, and the dual role of Bi3+ in trapping electrons and holes have been studied in Bi3+ or/and Ln3+ (Ln=Tb or Pr) doped LiScGeO 4 family of compounds by vacuum referred binding energy (VRBE) diagram construction, thermoluminescence, and spectroscopy. Electron release from Bi2+ has been evidenced. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF with benzo-2,1,3-thiazole units shows a high 74 % luminescence quantum yield. • MOF demonstrates luminescence quenching response to gossypol in cottonseed oil. • gossypol detection in sunflower oil allows to detect oil adulteration. A new 3D metal–organic framework {[Cd 16 (tr 2 btd) 10 (dcdps) 16 (H 2 O) 3 (EtOH)]∙15DMF} n (MOF 1 , tr 2 btd = 4,7-di(1,2,4-triazol-1-yl)benzo-2,1,3-thiadiazole, H 2 dcdps = 4,4′-sulfonyldibenzoic acid) was obtained and its luminescent properties were studied. MOF 1 exhibited bright blue-green luminescence with a high quantum yield of 74 % and luminescence quenching response to a toxic natural polyphenol gossypol and luminescence enhancement response to some trivalent metal cations (Fe3+, Cr3+, Al3+ and Ga3+). The limit of gossypol detection was 0.20 µM and the determination was not interfered by the components of the cottonseed oil. The limit of detection of gallium(III) was 1.1 µM. It was demonstrated that MOF 1 may be used for distinguishing between the genuine sunflower oil and oil adulterated by crude cottonseed oil through qualitative luminescent and quantitative visual gossypol determination. [ABSTRACT FROM AUTHOR]

The applicability of ruthenium tris(bipyridine) complexes in fields like photoactivated chemotherapy or photocatalysis requires in-depth understanding of their excited state deactivation mechanism. In particular, the quenching of luminescence from the lowest triplet metal-to-ligand charge-transfer (▪) excited state or the ligand photorelease relies on the fine-tuning of the energetics of the higher-lying metal-centered excited states (▪). In this contribution, we critically review different kinetic models commonly used to interpret the thermal activation of the ▪ excited states from the lowest ▪ minimum. Further, we extend our recently introduced kinetic model (Angew. Chem. Int. Ed. 2023, 62, e202308803) for ▪ (bpy = 2,2'-bipyridine) to a set of homoleptic tris(bipyridine)ruthenium (II) derivatives. This set has been selected to cover a wide range of electron -withdrawing/-donating substituents in the periphery of the bipyridyl ligands (4,4'-▪-2,2'-bpy; R= ▪, ▪, ▪, ▪, ▪▪, and ▪), on the basis of the Hammett's constant of the R functional group. Our calculations show that complexes with electron donating groups decay predominantly via one Jahn-Teller isomer (the so-called ▪ -trans conformation), while those with electron withdrawing ligands tend to decay through a different one (the ▪-cis Jahn-Teller isomer). We discuss structure/property relationships with focus on how to steer the energetics of the ▪ excited states. This work opens the pathway to rationally use ligand substitution to enhance or quench the lifetimes of the ▪ state and also provides guidelines to understand better non-radiative deactivation mechanisms in metal complexes. • Ruthenium complexes exhibit tunable emission, making them applicable in a variety of light harvesting processes. • Deactivation via triplet metal-centered states is key to determine non-radiative rates to the electronic ground state. • Different Jahn-Teller isomers of the ▪-minima need to be considered to predict accurate emission lifetimes. • Non-radiative deactivation is controlled by different ▪ Jahn-Teller isomers depending on the substitution pattern. [ABSTRACT FROM AUTHOR]

Developing new hybrid materials is critical for addressing the current needs of the world in various fields, such as energy, sensing, health, hygiene, and others. C-dots are a member of the carbon nanomaterial family with numerous applications. Aggregation is one of the barriers to the performance of C-dots, which causes luminescence quenching, surface area decreases, etc. To improve the performance of C-dots, numerous matrices including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and polymers have been composited with C-dots. The porous crystalline structures, which are constituents of metal nodes and organic linkers (MOFs) or covalently attached organic units (COFs) provide privileged features such as high specific surface area, tunable structures, and pore diameters, modifiable surface, high thermal, mechanical, and chemical stabilities. Also, the MOFs and COFs protect the C-dots from the environment. Therefore, MOF/C-dots and COF/C-dots composites combine their features while retaining topological properties and improving performances. In this review, we first compare MOFs with COFs as matrices for C-dots. Then, the recent progress in developing hybrid MOFs/C-dots and COFs/C-dots composites has been discussed and their applications in various fields have been explained briefly. [Display omitted] • Comparison of MOF and COF as support for C-dots is presented. • Methods for hybridization of MOF and COF with C-dots have been discussed. • Described are the generated and synergistic properties of the hybrid materials. • The main applications of MOF/C-dots and COF/C-dots have been addressed. [ABSTRACT FROM AUTHOR]

This study explores the structural and optical qualities of LaCa 4 O(BO 3) 3 (LACOB) phosphors doped with Eu3+, Dy3+, and Tb3+ using a microwave-assisted sol-gel technique. It uncovers oxygen-related luminescence defects in LACOB, highlighting emission peaks at 489 and 585 nm for Dy3+, a distinct sharp peak at 611 nm for Eu3+ in the red spectrum, and a notable green emission for Tb3+ due to specific transitions. The photoluminescence (PL) analysis indicates that luminescence is optimized through precise doping, leveraging dipole interactions, and localized resonant energy transfer, which are influenced by dopant concentration and spatial configuration. Temperature studies show emission intensity variations, particularly noticeable below 100 K for Tb3+ doped samples, demonstrating the nuanced balance between thermal quenching and luminescence efficiency. This temperature dependency, alongside the identified optimal doping conditions, underscores the potential of these materials for advanced photonic applications, offering insights into their thermal behavior and emission mechanisms under different conditions. [Display omitted] • Novel Eu3+, Tb3+, and Dy3+ Doped LaCa 4 O(BO 3) synthesized phosphors by microwave-assisted sol-gel technique. • Optimal Eu3+, Dy3+ and Tb3+ levels identified for peak emission. • Concentration quenching observed beyond optimal doping. • CIE analysis confirms consistent color output for tech applications. [ABSTRACT FROM AUTHOR]

Luminescent materials with desirable properties are in constant demand for lighting applications and as probes in bioimaging. In this study, we successfully synthesized nanosized strontium fluorapatite (SrFAp) powders doped with varying concentrations of Eu3+ ions via the hydrothermal method, targeting applications in lighting and bioimaging probes. Our focus was on understanding the impact of annealing temperature and dopant concentration on structural purity, particle morphology, photoluminescence, dopant ion occupancy, and temperature-dependent emission characteristics. The materials emit red light, with the most intense transition being 5 D 0 → 7 F 2. The asymmetry parameter (R) determination and CIE color coordinates provided insights into the spectroscopic attributes. Emission spectra were measured and discussed at four distinct excitation lines. Lower-energy excitation wavelengths, deemed favorable for organisms, make these materials particularly suitable for bioimaging applications. While the most intense emission occurred under 393 nm excitation, emissions were also detected at 464.5 nm and 525 nm, suggesting alternative excitation wavelengths better suited for bioimaging. Additionally, we conducted extensive studies to assess the effect of ambient temperature on the emission intensity of SrFAp materials doped with 1 mol% Eu3+ ions. Thermal quenching of luminescence was observed in both as prepared and annealed materials, providing insights into the temperature-dependent behaviour of the emission properties. • Nanosized Eu3+:Sr 10 (PO 4) 6 F 2 materials were synthesized by hydrothermal method. • The influence of Eu3+ content and annealing temperature on luminescence properties were studied. • Emission spectra were measured using two excitation wavelengths more friendly for bioimaging. • The emission intensity decreases as the ambient temperature increase. • A wide emission band around 430 nm was observed below 0°C that undergoes thermal quenching. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compound 1 displays a single excitation double emission in aqueous suspensions. • The luminescence properties of 1 was exploited as a multi-responsive luminescence sensor of nitrofuran antibiotics and triazine pesticides. • 1 has been successfully used in the field of antibiotic and pesticide detection of dual-function test strips. In recent years, there has been an increasing concern for health and food safety due to the severe environmental pollution caused by the overuse of antibiotics and pesticides. Effective and accurate detection of these species is of great importance in many fields. In this paper, a two-dimensional lanthanide organic framework [Tb(dobpdc) 1.5 (DEA) 2 ] n (1) was synthesized using 4,4′-dihydroxy-3,3′-biphenyl dicarboxylic acid ligand (H 2 L) with Tb(III) ion in the atmosphere of N,N'-diethylacetamide (DEA) and deionized water as solvents by solvothermal method. Compound 1 displays a single excitation double emission in aqueous suspensions. The luminescence properties of 1 were exploited as a multi-responsive luminescence sensor for nitrofuran antibiotics (nitrofurazone, nitrofurantoin) and triazine pesticides (metamitron) with a low detection limit and high selectivity via dual emission "turn-off" luminescence quenching. 1 has also been successfully applied to the construction of portable test strips for the detection of antibiotics and pesticides. In addition, the mechanism of fluorescence quenching has also been further discussed. [ABSTRACT FROM AUTHOR]

Double perovskite Ca 3 LiSbO 6 : x %Mn4+, y %Eu3+ far-red emitting phosphors with zero-thermal quenching properties as well as the sensitization effect of Eu3+ ions were reported. The Ca 3 LiSbO 6 :0.4%Mn4+ phosphor showed an emission intensity of 109 % at 423 K compared with that at 298 K. In addition, the emission intensity of Ca 3 LiSbO 6 :0.8%Mn4+, 4%Eu3+samples can be enhanced to about 1.25 times that of Ca 3 LiSbO 6 :0.4%Mn4+ due to the sensitization of Eu3+ ions. Meanwhile, the Ca 3 LiSbO 6 :0.8%Mn4+, 4%Eu3+ phosphor showed an internal quantum efficiency (IQE) of 78.9 % as compared with that of Ca 3 LiSbO 6 :0.4%Mn4+ (60.7 %), and the external quantum efficiency (EQE) also enhanced from 52.8 % to 68.5 % at the same time. Under the excitation of 365 nm light, the Ca 3 LiSbO 6 : x %Mn4+, y %Eu3+ samples display an emission peak at 698 nm, which is appropriate for the absorption of plant pigments including chlorophyll a , b and phytochrome of PFR. The result indicates that the Ca 3 LiSbO 6 : x %Mn4+, y %Eu3+ phosphors may have a potential in the application fields of pc-LEDs and indoor plant cultivations. [Display omitted] • Energy transfer process from Eu3+ to Mn4+ was observed in Ca 3 LiSbO 6 host. • Sensitization of Eu3+ ions results in a high IQE of 78.9 % for CLSO:0.8%Mn4+, 4%Eu3+ phosphor. • The CLSO:0.4%Mn4+ phosphor showed a zero thermal quenching performance with 109 % PL intensity maintained at 423 K. [ABSTRACT FROM AUTHOR]

Location of lanthanide levels in the bandgap, vacuum referred binding energy (VRBE) in the lanthanide ground state and energy of lanthanide charge transition levels (CTLs) are just three different namings for the same concept. A concept of importance for the performance of lanthanide activated compounds. Energy differences of CTLs with the conduction band bottom and valence band top are important when it concerns e.g. lanthanide luminescence, charge carrier trapping, and valence stability. Effect of temperature on CTL energy or VRBE has so far never been addressed despite that luminescence application and thermoluminescence studies may span a temperature range from 10 K to 1000 K. In this work information on the bandgap (or energy of host exciton creation) around 10 K and at RT in compounds is gathered to demonstrate that bandgap decreases by 0.1 eV to 0.3 eV when temperature increases to RT. A similar decrease will be demonstrated for the energy of electron transfer from the VB to a trivalent lanthanide. The findings have consequences for VRBE-diagram construction, i.e. the experimental parameters for such construction should all apply to the same temperature. They also have consequences on how to relate luminescence thermal quenching energy barriers and TL derived electron and hole trap depths with a VRBE diagram. By proper evaluating the effects of temperature, accuracy of VRBE diagrams and consistency with luminescence and thermoluminescence data can be improved. • Data has been collected on temperature dependence of bandgap and Eu charge transfer band energies. • The effect on VRBE schemes, lanthanide trap depths and quenching temperature has been explored. • Lanthanide and conduction band levels move down and anion levels move up with temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • A two-dimensional europium coordination polymer [Eu(dlba)(phen)·2(H 2 O)]n (CP-1) was prepared based on 1,10-phenanthroline and 2-(3,5-dicarboxybenzyloxy) benzoic acid. • The CP-1 exhibits excellent water stability and thermal stability. • The CP-1 shows good sensitivity, rapid response time and low detection limit in detection dipicolinic acid. The development of luminescence sensors capable of detecting anthrax biomarkers is crucial for preventing anthrax. In this study, a two-dimensional europium coordination polymer [Eu(dlba)(phen)·2(H 2 O)] n (CP-1) was prepared based on a rigid 1,10-phenanthroline (phen) and a flexible 2-(3,5-dicarboxybenzyloxy) benzoic acid (H 3 dlba) under the hydrothermal conditions. The CP-1 was characterized by powder X-ray diffraction, elemental analysis, thermogravimetric analysis, infrared spectroscopy, and single crystal X-ray diffraction. The CP-1 exhibits excellent water stability and thermal stability. Luminescence experiments demonstrated a high luminescence quenching efficiency (98.1 %) upon addition of the anthrax biomarker dipicolinic acid (DPA). Additionally, the sensor shows good sensitivity and a rapid response time of 30 s. The detection limit is as low as 0.12 µM, which is much lower than the infection dose of spores (60 µM). The sensor has a recovery rate of 95–105 % when tested on actual samples, indicating its potential for practical applications. The luminescence quenching effect may be due to the competitive absorption of DPA, which affects the efficiency of energy transfer from the ligands to the europium ions. [ABSTRACT FROM AUTHOR]

The structural, optical properties and underlying photophysical phenomena controlling the luminescence of PPy modified ZnO nanoplates are discussed in details here. Scanning electron micrographs reveal that the size of ZnO nanoplates prepared in presence of PPy decreases as compared to that of pristine ZnO. The crystallite size obtained from XRD for the PPy modified ZnO nanoplates also decreases as compared to that of pristine ZnO. O1s core level XPS spectra of ZnO synthesised in presence of PPy as well as pure ZnO show that oxygen vacancy in ZnO decreases in presence of PPy than that of pure ZnO. This in turn helps to reduce the visible emission and enhance UV emission from the ZnO nanoplates obtained in presence of PPy. The overall emission intensity of PPy modified ZnO samples decreases as compared to pristine ZnO. This indicates that apart from the modification of defect states of ZnO, different photophysical interactions like Forster Resonance Energy Transfer (FRET) as well as charge transfer also come into play to quench the overall luminescence of PPy modified ZnO. [ABSTRACT FROM AUTHOR]

The novel phosphors Ba 6 (Lu 1– x Eu x) 5 B 9 O 27 (x = 0.02, 0.04, 0.06, 0.08, 0.1, 0.14, 0.2) were obtained by cooling from a melt. Single-crystal X-ray diffraction experiments were provided for all the samples. No structural transitions caused by the Eu3+ → Lu3+ isomorphic substitution were revealed in this series of solid solutions. The data showed that an expected increase of cell parameters is caused by an increase in the Eu3+ content. First, the Eu3+ ions occupy large [Lu2O 6 ] and [Lu3O 6 ] polyhedra that are the most suitable ones for them, then (at x = 0.14) they start to occupy the smallest [Lu1O 6 ] polyhedra. Luminescent properties of the Ba 6 (Lu 1– x Eu x) 5 B 9 O 27 (x = 0.02–0.2) phosphors were investigated. The highest emission intensity with quantum yield of 28% was demonstrated by Ba 6 (Lu 0.92 Eu 0.08) 5 B 9 O 27. The concentration quenching effect was revealed for the 0.1 ≤ x ≤ 0.2 samples that could be caused by a beginning of the substitution of the smallest [Lu1O 6 ] polyhedra. It was shown that the successive substitution occurs at several cation positions of different sizes affects the quenching of luminescence. • Novel red-emitting phosphors Ba 6 Lu 5 B 9 O 27 :Eu3+ are synthesized. • Steady-state and kinetics luminescent properties of the phosphors are studied. • CIE coordinates are found to be close to those for the NTSC standard red phosphor. • Optimal concentration of Eu3+ depends on a sequential occupation of independent sites. [ABSTRACT FROM AUTHOR]

Upconversion luminescence materials have gained extensive attentions owing to their unique luminescence characteristics of converting near-infrared excitation to visible light emission. However, how to improve the doping concentration of activator (usually <3 mol%) in traditional sensitizer-activator system is still a great challenge due to the luminescence quenching effect. In this work, NaErF 4 crystals with diverse crystal phases and morphologies were prepared by simple hydrothermal method, constructing a 100% doping concentration system of activator (Er3+). With the increase of F− content, the phase of NaErF 4 transfers from cubic to hexagonal, and the morphology changes from nanospheres to hexagonal microflakes, meanwhile, the upconversion luminescence intensity also increases gradually. In addition, in order to further inhibit the luminescence quenching effect of NaErF 4 bare core, a series of NaErF 4 @SiO 2 core-shell samples with different SiO 2 shell thickness were successfully prepared. Compared with NaErF 4 bare core, the morphology and structure of the NaErF 4 @SiO 2 core-shell samples have no obvious change, but the UC luminescence intensity is significantly enhanced. Interestingly, the change of NaErF 4 crystal phase and SiO 2 shell thickness can both bring about multicolor luminescence. In addition, different from the traditional NaYF 4 :Yb, Er co-doping system, the as-prepared hydrophilic NaErF 4 and NaErF 4 @SiO 2 samples showed a greater red to green ratio (R/G > 1), which may expand their potential applications in biological imaging and sensing fields. [ABSTRACT FROM AUTHOR]

A nine-metal Zn(II)-Nd(III) nanoring with a diameter of about 2.3 nm was constructed for the rapid and ratiometric fluorescence detection of explosive 2,4,6-trinitrophenol at the ppm level. [Display omitted] • 2,4,6-Trinitrophenol (TNP) is detected firstly by a NIR luminescent high-nuclearity d-4f nanomolecular sensor. • The ratiometric fluorescence detection of TNP is fast and reliable. • The ratiometric fluorescence detection of TNP is highly sensitive and selective. Rapid and quantitative detection of 2,4,6-trinitrophenol (TNP) is very crucial for homeland security, military application, and environment protection. Herein, a nine-metal Zn(II)-Nd(III) nanoring 1 with a diameter of 2.3 nm was constructed by the use of a long-chain Schiff base ligand, which shows ratiometric fluorescence response to TNP with high selectivity and sensitivity. The fluorescence sensing behavior of 1 to TNP is expressed by a first-order equation I 1060nm / I 560nm = -0.0128*[TNP] + 0.9723, which can be used to quantitatively analyze TNP concentrations in solution. The limits of detection (LODs) to TNP based on the ligand-centered (LC) and Nd(III) emissions of 1 are 5.93 μM and 3.18 μM, respectively. The fluorescence response mechanism to TNP is attributed to the competitive absorption effect and photoinduced electron transfer (PET). The luminescence quenching of 1 is dominated by static process. [ABSTRACT FROM AUTHOR]

• Achieved optimal luminous intensity by systematically adjusting the doping ratios of rare earth elements of the material. • Discussed the energy transfer processes within the Nd-Yb-Er system. • Investigated the impact of Yb doping concentration in the middle layer on luminescence of the core-shell-shell structure. [Display omitted] In the second near-infrared window (NIR-II), biological tissues exhibit lower light scattering and allow for deeper tissue penetration of photons. In the Nd-Yb-Er co-doped NIR-II emissive systems, it has been demonstrated that multi-layered core-shell structures can effectively inhibit luminescence quenching. In this structure, the compositions of each layer will impact luminous efficiency, with a complex energy transfer process involved. Herein, we meticulously optimized the doping concentrations in each layer of the NIR-II nanoparticles, and discussed their influence on the energy transfer process within this system. Compared to conventional materials, the optimized materials produce sharper imaging results in mouse vascular imaging. [ABSTRACT FROM AUTHOR]

The quenching of luminescence in Er3+/Yb3+ co-doped with Tm3+ presents a dilemma as it substantially diminishes thermometric performance. In this study, Y 2 O 2 S: Er3+/Yb3+/Tm3+ phosphors were synthesized using a homogeneous precipitation method combined with a sulfurization process. In addition, three sets of fluorescence intensity ratio (FIR) models were designed, which have self-calibration function. The effects of incorporation of Li+ or Li+/Ba2+ on the up-conversion luminescence (UCL) intensity and thermometric performance of the phosphors were systematically studied. The results show that the introduction of Li+ or Li+/Ba2+ co-doping leads to lattice distortion and the formation of oxygen ion vacancies in the lattice, which further accelerates the energy transfer process and mixes the charge transfer states, and ultimately dramatically improves the UCL and thermometric performance. The introduction of Li+ and Li+/Ba2+ co-doping enhanced the UCL of the materials by about 3.7 times and 5.6 times compared to Y 2 O 2 S: Er3+/Yb3+/Tm3+. When based on nonthermally coupled levels (NTCLs), the S r-max of Li+/Ba2+ co-doped sample is 0.080 K−1 at 573 K, which is 87 % higher than that based on TCLs. These findings not only provide a new avenue for improving the UCL and thermometric performance but also provide an accurate self-calibration FIR model over a wide temperature range. • Monodisperse spherical Y 2 O 2 S:Er3+/Yb3+/Tm3+ phosphors were successfully synthesized. • A simple, accurate, low cost and large-scale production method for rare earth doped Y 2 O 2 S phosphors was proposed. • The effects of Li+ and Li+/Ba2+ ions on enhancement of optical performance were investigated systematically. • Three sets of fluorescence intensity ratio models were designed and a self-calibration function was obtained. [ABSTRACT FROM AUTHOR]

• A coordination polymer synthesized from carboxylic acid ligand and nitrogen containing ligand. • Chain structure with a very rare (4,4)(2,3) topology that has not yet been found in other valence-bonded coordination compounds has been presented. • The coordination polymer can be used as a multifunctional fluorescent probe with high selectivity and excellent sensitivity to detect Fe3+, Cr 2 O 7 2− and CrO 4 2−. • The possible quenching mechanism of the selective detection was presented. One Cadmium(II)-based complex, [Cd(LBIX)(HEA)] n (1), was synthesized using 4,4′-bis((1H-imidazol-1-yl)methyl)-1,1′-biphenyl (LBIX) and 1,2-phenylenediacetic acid (H 2 HEA) as ligands. The analysis of the single crystal structure reveals that 1 possesses a ladder-like chain structure, which extends into a 3D architecture through π···π interactions. 1 was identified through powder X-ray diffraction analysis (PXRD), elemental analysis (EA), infrared spectroscopy (IR) and thermogravimetric analysis (TGA). It can be seen from the luminescence experiment that 1 has high K sv value (Cr 2 O 7 2−: 1.51 × 104 M−1, CrO 4 2−: 1.16 × 104 M−1 and Fe3+: 1.26 × 104 M−1) and lower detection limit (Cr 2 O 7 2−: 1.14 μM, CrO 4 2−: 1.88 μM and Fe3+: 1.14 μM), it is utilized as a multi-response sensor to recognition Fe3+, CrO 4 2− and Cr 2 O 7 2− in an aqueous solution. Mechanisms in which fluorescence quenching occurs have been examined using techniques such as PXRD, UV–vis absorption spectra, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Due to its excellent selectivity, high sensitivity and strong stability, it is suitable for detecting Fe3+, CrO 4 2− and Cr 2 O 7 2− ions as a fluorescent probe. One novel coordination polymers (CPs), namely, [Cd(LBIX)(HEA)] n (1) (LBIX = 2-(N-methylimidazole)biphenyl, H 2 HEA = 1,2-phenylenediacetic acid) was synthesized. Three helical chains with the same direction intertwine with each other to form a complete 1D chain structure of coordination polymer. 1 forms 3D supramolecular structure through π···π interaction along a axis. The luminescent experiments showed that complex 1 can act as a turn-off luminescent probe for sensitivity. [Display omitted] [ABSTRACT FROM AUTHOR]

A unique mixed valence copper-based luminescent MOF is constructed by a new AIE ligand to exhibit highly efficient TNP sensing. [Display omitted] Designing and synthesizing functional metal–organic frameworks (MOFs) remains great challenges. In this study, a new aggregation-induced-emission (AIE) molecule 4,4′-(((9H-fluoren-9-ylidene)methylene)bis(4,1-phenylene))dipyridine (L) was developed as functional ligand to construct a unique MOF [Cu(I) 2 Cu(II) L 2 (SCN) 4 ] n (1) with mixed-valence Cu centers. 1 is fabricated by 4-connected Cu(II) and Cu(I) building units, and "V" shaped L and linear SCN− bridges, and forms a three-dimensional (3-D) binodal (4, 4)-connected framework with rare non-interpenetrated (64·82)(66) 2 network. 1 demonstrates excellent water, pH and thermal stabilities, and can efficiently detect TNP in aqueous medium. Its quenching constant and detection limit for sensing TNP reach 2.16 × 105 M−1 and 1.05 × 10−5 mM, respectively, which are better than those of the most MOF-based TNP sensors. Moreover, 1 exhibits notable TNP sensing selectivity and recyclability. The luminescence quenching sensing mechanism of 1 toward TNP is in-depth investigated. [ABSTRACT FROM AUTHOR]

A thermally and hydrolytically stable 1D zinc coordination polymer with 1,4-bis((2-methylimidazol-1-yl)methyl)benzene demonstrates highly sensitive and selective sensing properties towards nitrofuran antibiotics with part- per -billion limits of detection through luminescence quenching. [Display omitted] With the harm caused by the misuse of antibiotics, the problem of water pollution has attracted much attention. Besides, water resources are closely related to human health. Therefore, the development of efficient and rapid methods for the detection of antibiotics is an important and urgent task. Here, a series of isostructural metal–organic framework materials (SYUCT-M, M = Zn, Co) was synthesized, SYUCT-Zn demonstrated sensing properties for efficient detection of nitrofuran antibiotics (NFAs). The detection limits of nitrofurazone (NFZ), furazolidone (FZD) and nitrofurantoin (NFT) by SYUCT-Zn were 1.47 ppb, 1.73 ppb and 2.43 ppb, respectively. Meanwhile, a fast response time and anti-interference ability of SYUCT-Zn is outstanding for 12 antibiotics in 5 classes. Apart from the sensitivity and selectivity, SYUCT-Zn featured excellent stability in acidic, basic or organic solvent media. Recyclability of SYUCT-Zn sensor was established, which indicates its great potential as sensory material for antibiotics detection. [ABSTRACT FROM AUTHOR]

A novel three-dimensional terbium (III)-based metal-organic framework, [Tb(TDC)(µ 2 -CH 3 COO)(H 2 O)] (Tb-MOF , H 2 TDC = 2,5-thiophenedicar-boxylic acid), was designedly synthesized with TDC ligands under solvothermal conditions. The Tb-MOF features a 3D network constructed by bridging a 2D wave-like network connected by TDC ligands with monodentate coordination modes to form a 3D net framework. Furthermore, by applying Tb-MOF as a fluorescent probe, a convenient and rapid sensor was constructed for the sensing of nitroimidazole antibiotics, including metronidazole (MDZ), dimetridazole (DTZ), and ornidazole (ODZ). [Display omitted] • A novel 3D Tb-MOF was synthesized by the self-assembly mode under solvothermal method. • It demonstrates a high QY of 55.0 % and an average fluorescent lifetime of 534 µs. • It exhibits excellent selectivity towards nitroimidazole antibiotics. • A portable test paper was designed for rapid sensing of nitroimidazole antibiotics. A new 3D terbium (III)-based metal–organic framework, [Tb(TDC)(µ 2 -CH 3 COO)(H 2 O)] (Tb-MOF , H 2 TDC = 2,5-thiophenedicar-boxylic acid), was obtained with Tb3+ ions as metal source and TDC ligands as the auxiliary ligand through self-assemble mode. The Tb-MOF features a 3D network constructed by bridging a 2D wave-like network connected by TDC ligands with monodentate coordination mode, which results in the formation of a 3D net framework. The luminescent properties and sensing antibiotics experiments were extensively investigated for the Tb-MOF. Remarkably, the Tb-MOF exhibits a substantial quantum yield (QY) at 55.0 % and an average photoluminescence lifetime of 534 µs. Furthermore, the Tb-MOF shows selective luminescence quenching for nitroimidazole antibiotics, including metronidazole (MDZ), dimetridazole (DTZ), and ornidazole (ODZ), with a particularly strong response for MDZ (K sv = 5.49 × 104 M−1, LOD value is 7.9 × 10−5 M). Finally, the Tb-MOF enables a simple and convenient test paper that allows luminescent color changes to be observed with the naked eye for detecting MDZ. [ABSTRACT FROM AUTHOR]

The photoluminescence of terbium(III) chloride in liquid ammonia at 293 K and 8.8 atm is considered. The solubility of TbCl 3 crystal hydrate in ammonia is 5∙10−4 mol/L. The luminescence spectrum of the solvated Tb3+ ion in this solution coincides with the luminescence spectrum of the hydrated Tb3+ ion in a similar aqueous solution at atmospheric pressure. The measured excited state (5D 4) lifetime τ of the terbium ion is somewhat longer in ammonia (470 μs) than in water (420 μs). The (Tb3+)* luminescence in ammonia is quenched by solvated electron (e s –), formed upon dissolution of lithium metal. Under these conditions, a solution of Tb3+ and e s – is unstable, precipitate is being formed, and continuous change in the component concentrations takes place. This hampers obtaining an adequate Stern-Volmer dependence of the Tb3+ luminescence intensity on the concentration of the quencher e s –, which is determined by measuring the absorbance of the solution at 1400 nm at the absorption band of e s –. A linear dependence was obtained by measurement of terbium ion τ with variable e s – concentration. The results were used to calculate the bimolecular rate constant k = (3.2 ± 0.3)∙108 M−1s−1 for the assumed quenching reaction (Tb3+)* + e s – → Tb2+. [Display omitted] • The Tb3+ ion photoluminescence was recorded in liquid NH 3 • The e s −, generated by dissolving Li in NH 3 , quenches Tb3+ photoluminescence • The quenching occurs via (Tb3+)* + e s –.→ Tb2+ reaction • The quenching reaction rate constant was found from (Tb3+)* lifetime dependence on [e s −] [ABSTRACT FROM AUTHOR]

[Display omitted] • The terephthalic acid, 2, 5-furandicarboxylic acid, and Samarium and Europium nitrate salts was used to synthesis a samarium/europium-metal organic frameworks. • Sm/Eu-MOF can specifically luminescence detect Cr3+, Pb2+, and acetone in aquatic solution. • The limit of detection for Cr3+, Pb2+, and acetone are 0.85 μM, 0.46 μM, and 1.04 μM, respectively. With outstanding detection selectivity and sensitivity characteristics, samarium/europium-metal organic frameworks (Sm/Eu-MOF) is capable of functioning as a versatile light-emitting sensor particularly for detecting acetone, Cr3+, and Pb2+ in aqueous environment. While considering maximum detectable concentrations of 0.85 μM, 0.46 μM, and 1.04 μM, respectively, competitive energy interactions for acetone, absorption of energy for Cr3+, and substitution of ions for Pb2+ are the elucidated mechanisms of detecting these substances by Sm/Eu-MOF. Successful formulation and synthesis of a core–shell structured Sm/Eu-MOF, which has endurance to acid/alkali conditions and hydration/heat-stability, can be accomplished by utilizing Samarium and Europium nitrate ions, terephthalic acid, and 2, 5-furandicarboxylic acid. The recovery rate of acetone, Cr3+, and Pb2+ detection from real samples were 95.0–101.0 %, 99.8–101.0 %, and 99.9–104.0 %, respectively. [ABSTRACT FROM AUTHOR]

Herein, the triple-atomic nanozyme (TAzyme) Fe/Zn/Ir with high peroxidase (POD)-like and luminescent properties is employed to sensitively detect melatonin (MT) with colorimetric and luminescent modes. [Display omitted] • The triple-atomic enzyme (TAzyme) Fe/Zn/Ir is prepared without high temperature and pyrolysis procedures. • Fe/Zn/Ir not only has high POD-like activity, but also possesses interesting luminescence properties. • The developed dule-mode detection provides new conception to detect other biological molecules. • Fe/Zn/Ir is fabricated into the test swabs which can effectively monitor MT in the portable and naked-eye way. Herein, a novel ternary-atomic Fe/Zn/Ir nanozyme (Fe/Zn/Ir TAzyme) with peroxidase (POD)-like and luminescence properties is fabricated through coordinating Ir(III) complex into the as-prepared Fe/ZIF-8. The preparation procedures avoid high-temperature and pyrolysis which endue Fe/Zn/Ir nanocomposite with high stability and can be scaled up. Once Fe/Zn/Ir TAzyme catalyzes the substrate TMB to produce blue oxidized TMB (oxTMB), its luminescence is quenched by the generated oxTMB. Ascribed to its high POD-like activity and interesting luminescence property, a dual-mode sensing platform for the detection of melatonin (MT) is fabricated. In the presence of increasing concentrations of MT, the absorbance of the detection system declines, while the emission of the detection system grows. The detection platform exhibits the limits of detection (LODs) in colorimetric and luminescence detections are 8.9 nM and 8.8 nM, respectively, which can mutually validate the assay results. More importantly, Fe/Zn/Ir TAzyme has been fabricated into test swabs to monitor MT in the way of portable and naked-eye detection. This double-role TAzyme provides new conceptions for researchers to explore novel and highly efficient nanozymes in future. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation into the structural and luminescent properties of lanthanide 2-hydroxybenzoate compounds, focusing on Eu3+ and Tb3+ ions in both single and mixed systems. The X-ray structures of (Hphen) 2 [Eu 2 (2-OHBz) 8 (H 2 O) 2 ]·2H 2 O (1a ·2H 2 O) and [Eu(2-OHBz) 3 (phen) 2 ]·PhMe (2a ·PhMe) were determined, where 2-OHBz: 2-hydroxybenzoate and phen: 1,10-phenantroline, revealing triclinic crystal structures with distinct coordination geometries. Compound 1a ·2H 2 O displayed a centrosymmetric dinuclear anion with a coordination number of eight for each Eu3+ center, while compound 2a ·PhMe exhibited a neutral mononuclear complex with a decacoordinated Eu3+ center. A comparative analysis of luminescent properties between these compounds unveiled significant differences in the nonradiative decay rates of the 5D 0 level of Eu3+ ions, suggesting potential luminescence-quenching channels. The investigation is extended to mixed Eu3+-Tb3+ systems, demonstrating efficient Tb3+ to Eu3+ energy transfer, especially at room temperature. Three models, including two novel ones proposed in this study, were considered to rationalize energy transfer in the mixed systems. Our theoretical-experimental investigation reveals that variations in lifetimes of the emitting level 5D 0 of Eu-2-OHBz mononuclear and binuclear complexes, or mixed Eu/Tb-2-OHBz complexes, with 1,10-phenanthrolines, primarily result from multiphonon decay processes; however, low-energy ligand-to-metal charge transfer (LMCT) states play a key role in suppressing luminescence in the binuclear complex compare to the mononuclear ones. The image depicts X-ray structures of (Hphen) 2 [Eu 2 (2-OHBz) 8 (H 2 O) 2 ]·2H 2 O (1a) and [Eu(2-OHBz) 3 (phen) 2 ]·PhMe (2a), sample photos with UV illumination, energy transfer processes, and a luminescence decay curve modeled with three different approaches. These models are used to rationalize the luminescent properties of mononuclear and binuclear Eu/Tb-2-hydroxybenzoate complexes with 1,10-phenanthroline. [Display omitted] • Structural and luminescent properties of the mono and binuclear Eu/Tb-2-hydroxybenzoate complexes with 1,10-phenanthroline. • Luminescence activation and quenching of Eu3+ ions in mixed systems. • Novel models for understanding energy transfer and excited-state lifetimes in mixed lanthanide systems. [ABSTRACT FROM AUTHOR]

In this paper, we performed a comparative spectroscopic analysis of Tm3+-doped glasses based on GeO 2 -BaO-Ga 2 O 3 (GBG) and TiO 2 -GeO 2 -BaO-Ga 2 O 3 (TGBG) to achieve broadband luminescence at 1.8 μm. Glasses were prepared at different doping concentrations (0.05 mol% and 1mol%) in order to investigate the effect of Tm3+ ions as well as host composition (GeO 2 :TiO 2 molar ratios) on near-IR luminescence properties. We report on the hypersensitivity of the transition 3H 6 → 3F 4 of Tm3+ in a series of titanate-germanate glasses, which was shifted to longer wavelengths with increasing TiO 2 concentration. The relative intensity of the main near-IR emission band corresponding to the 3F 4 → 3H 6 (1.8 μm) transition of Tm3+ was 4.8-fold enhanced for glass with molar ratio GeO 2 :TiO 2 = 1:5 compared to GBG glass system. We observed the luminescence quenching phenomena for samples containing more than 0.5 mol% of Tm3+ ions. The calculated spectroscopic parameters, such as measured luminescence lifetime (τ m) and the quantum efficiency (η), were discussed and compared to the different laser glasses. Importantly, luminescence decay curves have been examined using the Inokuti-Hirayama model. Additionally, the correlation between optical properties and local structure in glasses was well evidenced by Raman spectroscopy. The proposed strategy, in combination with various chemical composition of glass host activated by various Tm 2 O 3 concentration, might be beneficial for modern near-infrared photonics. • NIR emission of Tm3+ in BGG glass was examined with TiO 2 and activator content. • The main band due to 3F 4.→ 3H 6 transition of Tm3+ was 4.8-fold enhanced. • The hypersensitive 3H 6.→ 3F 4 transition of Tm3+ was shifted to longer wavelengths. • The luminescence decay curves were examined by the Inokuti-Hirayama model. • Tm3+-doped glasses with GeO 2 :TiO 2 = 1:1, 1:2, 1:3 can be attractive for photonics. [ABSTRACT FROM AUTHOR]

Ceramic samples of two multi-cation fluoride compositions, namely Na 3 CaMg 3 AlF 14 doped with Ce3+ or Eu2+ and KCaAl 2 F 9 doped with Eu2+, have been synthesized using a conventional solid-state reaction method. The XRD analysis shows that the new polymorphic modification of Na 3 CaMg 3 AlF 14 with the cubic A 2 B 2 X 7 pyrochlore crystal structure (space group Fd 3 ‾ m , lattice parameter 10.172 Å) has been obtained. This conclusion is confirmed with the simulation of the XRD pattern for the cubic pyrochlore structure by introducing random occupation of Na+ and Ca2+ ions at the A-type sites as well as Mg2+ and Al3+ ions at the B-type sites in the structure of rhombohedral Na 3 CaMg 3 AlF 14. It has been shown that doping of the Na 3 CaMg 3 AlF 14 pyrochlore matrix with Ce3+ ions creates several Ce3+ optical centers with different spectral and decay properties of 5d-4f luminescence. In contrast to that, doping with Eu2+ ions creates a single optical center by the substitution for the Na/Ca A-type site in the cubic Na 3 CaMg 3 AlF 14 pyrochlore structure. In Eu2+-doped Na 3 CaMg 3 AlF 14 , the Eu2+ emission band caused by the interconfigurational 4f65d – 4f7 transition has a rather narrow width (FWHM = 29 nm) which is considerably less than that observed in Eu2+-doped KCaAl 2 F 9 (FWHM = 44 nm) in which the emission band is broadened due to the existence of two types of sites for doping Eu2+ ions. The Eu2+ ions doped into Na 3 CaMg 3 AlF 14 and KCaAl 2 F 9 hosts emit not only broad-band 4f65d – 4f7 luminescence but also a narrow-line 4f7 – 4f7 (6P 7/2 - 8S 7/2) emission which is not observed under excitation to the lowest-energy 4f65d state. It has been shown that both Na 3 CaMg 3 AlF 14 :Eu2+ and KCaAl 2 F 9 :Eu2+ demonstrate a rather good thermal stability of luminescence with thermal quenching temperature T 1/2 equal to 504 and 573 K, respectively. • Novel cubic polymorphic modification of Na 3 CaMg 3 AlF 14 pyrochlore has been synthesized. • Eu2+ ions create a single luminescence center in the cubic Na 3 CaMg 3 AlF 14 pyrochlore. • In the Na 3 CaMg 3 AlF 14 host Eu2+ ions show both 4f65d-4f7 and 6P 7/2 -8S 7/2 luminescence. • 4f65d-4f7 luminescence of Eu2+ doped into Na 3 CaMg 3 AlF 14 has high thermal stability. • Ce3+ ions create several luminescence centers in the cubic Na 3 CaMg 3 AlF 14 structure. [ABSTRACT FROM AUTHOR]

A novel cationic Mn-based metal-organic framework, composed of a 1D infinite Mn-chain and a rigid dicarboxylic viologen derivative, features a positively charged network. Remarkably, it exhibits multifunctional properties, including chemochromism, antibiotic detection and magnetic behavior. [Display omitted] • Compound 1 features a positively charged skeleton with triangular pores. • Compound 1 demonstrates a chemical chromism phenomenon for ammonia. • Compound 1 exhibits rapid and selective detection of antibiotics. • Magnetic property investigations reveal predominant antiferromagnetic coupling between Mn(II) ions within compound 1. Utilizing the rigid and linear viologen carboxylic ligand as an organic linker, we have successfully synthesized and structurally characterized a multifunctional Mn-based cationic metal-organic framework (1). Compound 1 features a three-dimensional framework structure with a positively charged skeleton, wherein triangular pores accommodate [MnCl 4 ]2− anions to preserve charge neutrality. Notably, compound 1 demonstrates a chemical chromism phenomenon, transitioning from yellow-brown to deep green upon exposure to ammonia. This color change is attributed to the nucleophilic attack of electron-rich ammonia molecules on the electron-deficient viologen moiety of viologen carboxylic ligand, leading to the formation of viologen radicals and charge transfer complexes. Moreover, compound 1 exhibits rapid and selective detection of antibiotics like metronidazole (MDZ) and dimetridazole (DTZ) via a competitive absorption-induced luminescence quenching process, featuring high quenching coefficients and low detection limits. Additionally, magnetic property investigations reveal predominant antiferromagnetic coupling between Mn(II) ions within compound 1. [ABSTRACT FROM AUTHOR]

The establishment of rapid target analysis methods for cytokeratin fragment antigen 21-1 (CYFRA 21-1) is urgently needed. [Ir(pbi) 2 (acac)] (pbi = 2-(4-bromophenyl)-1-hydrogen -benzimidazole, acac = acetylacetonate) as traditional electrochemiluminescence (ECL) luminophores has been confined due to its non-negligible dark toxicity and poor water solubility leading to poor biocompatibility and electrical conductivity as an organic molecule. Hence, to overcome this limitation, [Ir(pbi) 2 (acac)] can be effectively loaded on the polyvinyl alcohol hydrogel modified Ti 3 C 2 T x MXene surface (Ir@Ti 3 C 2 T x -PVA) as sensing platform which can emit high ECL signals. Then, a quenching strategy was proposed to fabricate an ECL sandwich immunosensor using H 2 O 2 as quencher molecules which can generated by Pd@Au 0.85 Pd 0.15. Especially, the generation of O 2 to H 2 O 2 can be achieved through a two-electron (2e–) reaction pathway by Pd@Au 0.85 Pd 0.15 , to overcome the restriction that the H 2 O 2 was virtually impossible to label or immobilize on the non-enzyme nanomaterials. The proposed ECL assay achieves a response to CYFRA 21-1 within the range of 0.1 pg/mL–100 ng/mL, with a detection limit of 8.9 fg/mL (S/N = 3). This work provided a feasible tactic to seek superior-performance ECL luminophore and quencher consequently set up a novel means to makeup ultrasensitive ECL biosensor, which extended the utilization potential of Ir(pbi) 2 (acac) in ECL assays. [Display omitted] • Ir@Ti 3 C 2 T x -PVA has high ECL efficiency. • Pd@Au 0.85 Pd 0.15 can through a two-electron reaction pathway to generate H 2 O 2. • H 2 O 2 can quench the ECL of Ir@Ti 3 C 2 T x -PVA. • The luminescence and quenching mechanisms are novel. [ABSTRACT FROM AUTHOR]

Both excess and deficiency of Cr3+ and Cu2+ ions can bring about certain abnormalities in human health, but it is still challenging to achieve great sensitivity and selectivity for sensing trace amount of copper and chromium ions due to the strong interference of coexisting ions in ambient water. To take advantage of excellent luminescence of rare earth (RE) ions and biodegradability and environmental friendliness of hydroxyapatite (HAP), novel luminescent Eu3+/Gd3+ co-doped hydroxyapatite (HAP/Eu-Gd) has been synthesized as a sensing material for the detection of Cu2+ and Cr3+ ions. Based on the fluorescence "turn-off" effect, Cr3+ and Cu2+ ions can be selectively recognized by their quenching fluorescence of the HAP/Eu-Gd. The HAP/Eu-Gd displays great sensitivity. Its limit of detection for Cu2+ and Cr3+ ions are 0.566 μM (35.967 μg/L) and 0.165 μM (8.579 μg/L), respectively, which are below the Cu2+ (2 mg/L) and Cr3+ (100 μg/L) contamination limits of drinking water stated from the United States Environmental Protection Agency. Moreover, the luminescence quenching mechanisms of the HAP/Eu-Gd for Cu2+ and Cr3+ ions were elucidated by X-ray diffraction, Fourier transform infrared spectra, UV-Vis adsorption spectra, photoluminescence studies and luminescence lifetime measurements. Our study paves the way for RE-doped HAP luminescent sensors in potential applications for metal ion detection. [Display omitted] • Environmentally friendly luminescent sensing material HAP/Eu-Gd was synthesized. • HAP/Eu-Gd was first applied to detect Cu2+ and Cr3+ ions • HAP/Eu-Gd detected Cr3+ and Cu2+ ions with high sensitivity and selectivity. • The luminescent sensing mechanism of HAP/Eu-Gd was revealed. [ABSTRACT FROM AUTHOR]