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Nowadays, the application scenarios of rare earth doped luminescent materials tend to be refined and complicated. The optical properties of rare earth doped materials are difficult to precisely control via the traditional design and synthesis methods, namely, changing doping concentration or preparative conditions. The aim of this study is to tune the optical transition properties of Er3+ in tungsto-molybdate NaY(Mo x W 1- x O 4) 2 (x = 0, 0.01, 0.1, 0.3, 0.5, 0.7, 0.9, 0.99 and 1.0) phosphors by changing the host matrix. The Er3+ doped continuous tungsto-molybdate solid solution NaY(Mo x W 1- x O 4) 2 phosphors were prepared via a solid state reaction technique at optimized calcination temperatures. The refractive indexes of the obtained solid solution samples were confirmed according to different models and compared. Subsequently, the optical transition intensity parameters, radiative transition rates and intrinsic radiative lifetimes of Er3+ in these solid solution phosphors were calculated in the framework of Judd-Ofelt theory. It was confirmed that the optical transition properties of Er3+ can be greatly tuned by the solid solution composition, and the tuning effects for different transitions are different. To validate the reliability of the Judd-Ofelt calculations, the temperature-dependent emission spectra of two green emissions of Er3+ for different solid solution samples were studied. It was found that the radiative transition rate ratios between two green emissions derived from theoretical calculations and experimental measurements are in reasonable agreement, thus proving that the optical transition calculations are reliable and the optical transition properties of Er3+ in the tungsto-molybdates can be tuned in a large range. This work reminds us of a new route for developing novel luminescence materials based on practical demands. [ABSTRACT FROM AUTHOR]

The extensive use of lanthanides in science, industry and high-technology products is accompanied by an anthropogenic input of rare earth elements into the environment. Knowledge of a metal's environmental fate is essential for reasonable risk assessment and remediation approaches. In the present study, Eu(III) was representatively used as a luminescent probe to study the chemical environment and to elucidate the molecular interactions of lanthanides with a suspension cell culture of Nicotiana tabacum BY-2. Biochemical methods were combined with luminescence spectroscopy, two-dimensional microspectroscopic mappings, and data deconvolution methods to resolve the bioassociation behavior and spatial distribution of Eu(III) in plant cells. BY-2 cells were found to gradually take up the metal after exposure to 100 μM Eu(III) without significant loss of viability. Time-resolved luminescence measurements were used to specify the occurrence of Eu(III) species as a function of time, revealing the transformation of an initial Eu(III) species into another after 24 h exposure. Chemical microscopy and subsequent iterative factor analysis reveal the presence of four distinct Eu(III) species located at different cellular compartments, e.g., the cell nucleus, nucleolus and cell walls, which could be assigned to intracellular binding motifs. In addition, a special type of bioaccumulation occurs through the formation of a Eu(III)-containing oxalate biomineral, which is already formed within the first 24 hours after metal exposure. Oxalate crystals were also obtained in analogous experiments with Gd and Sm. These results indicate that tobacco BY-2 cells induce the precipitation of metal oxalate biominerals for detoxification of lanthanides, although they also bind to other cellular ligands at the same time. [ABSTRACT FROM AUTHOR]

The influence of the degree of π-conjugation in biaroylmethane ligands upon Eu3+ luminescence efficiency in corresponding neutral tris-complexes was investigated in depth. The data obtained by both steady-state and time-resolved luminescence measurements gave an inside into electronic energy transfer mechanisms in the abovementioned complexes. It was shown that extension of the π-system in the naphthalene moiety in comparison to the phenyl one lead to a substantial decrease of both the S1 and T1 energy of the corresponding symmetrical β-diketones, which, in turn, led to a decrease of the total quantum yield of respective Eu3+ complexes. The obtained results are of interest for the rational design of highly luminescent complexes with NIR-emitting lanthanides, as the resonant levels energies are low and can hardly be sensitized by common ligands. [ABSTRACT FROM AUTHOR]

Two symmetric ligands harbouring two TEMPO radicals and two functionalized acetamide arms (R = OMe (L1), CF3 (L2)) were prepared and chelated to lanthanide ions (EuIII, YbIII for both L1 and L2, DyIII for L1). Luminescence measurements on the europium complexes support the coordination of a single water molecule. The TEMPO arms are magnetically interacting in L1 (and its complexes) but not in L2. The TEMPO moieties can be reversibly oxidized into an oxoammonium (0.33–0.36 V vs. Fc+/Fc) or reduced into a hydroxylamine (ill-defined redox wave, reduction by ascorbate), which are both diamagnetic. The europium complexes [Eu(L1)]3+ and [Eu(L2)]3+ in their hydroxylamine form exhibit a temperature dependent CEST effect, which is maximal at 25 °C (30%) and 37 °C (12%), respectively. The CEST activity is dramatically reduced in the corresponding nitroxide forms due to the paramagnetism of the ligand. The europium complexes show no cytotoxicity against M21 cell lines over long incubation times (72 h) at high concentration (40 μM). [ABSTRACT FROM AUTHOR]

Three lanthanide complexes (Ln=Gd, Eu) based on a DO3 A ([Ln(L1)]) or DO2 A ([Ln(L2–3)]+) platform appended by a redox active TEMPO‐based arm were prepared. Complex [Ln(L2)]+ shows an alkyne arm, offering the possibility of postfunctionalization by click reaction to yield [Ln(L3)]+. The complexes demonstrate a redox response whereby the hydroxylamine, nitroxide and oxoammonium forms of the arm can be obtained in turn. Luminescence measurements on the europium complexes support an octadentate (L1, L3) or heptadentate (L2) chelation by the ligand, with one water molecule in the inner coordination sphere. The relaxivity was determined from 20 kHz to 30 MHz by fast‐field cycling NMR. The three GdIII complexes under their hydroxylamine form [Gd(L1)] and [Gd(L2–3)]+ show r1 values of 7.0, 5.1 and 5.0 mM−1 s−1 (30 KHz), which increase to 8.8, 5.5 and 6.1 mM−1 s−1 in the nitroxide form. The radical complexes are not toxic against M21 cell lines, at least up to 40 μM. By using EPR spectroscopy we establish that they do not penetrate the cells with the exception of [Eu(L2)]+. [ABSTRACT FROM AUTHOR]

Rare earth (RE3+)-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at high temperatures. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc2(MoO4)3:Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er3+ are achieved upon raising the temperature from 298 to 773 K. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4I13/2 of Er3+ in Sc2(MoO4)3:Yb/Er displays a strong temperature dependence, enabling luminescence thermometry with the highest relative sensitivity of 12.3%/K at 298 K and low temperature uncertainty of 0.11 K at 623 K. These findings may gain a vital insight into the design of negative-thermal-expansion RE3+-doped phosphors for versatile applications. Rare-earth doped phosphors with negative thermal expansion (NTE) may display thermally-enhanced emission, but their performance is generally limited. Here the authors report thermally-boosted green upconversion luminescence and near-infrared downshifting luminescence in Sc2(MoO4)3:Yb/Er phosphors with two-dimensional NTE, and their application in temperature sensing. [ABSTRACT FROM AUTHOR]

Sorption-luminescent method for cerium determination based on natural Transcarpathian clinoptilolite without using of complex synthetic organic compounds and toxic solvents was proposed. Optimal luminophore preparation conditions are sorption of free Ce3+ ions by zeolite in the solution with pH 4.5. For luminescence measurements excitation by quanta with wavelength of 255 nm were used. Luminescence intensity at λ = 346 nm was selected as analytical parameter for a quantitative cerium determination. Features characteristic to Ce3+ and Ce4+ oxidation states were identified in XPS spectra from as-grown and annealed samples. Definable range of Ce(III) concentration with the detection limit of 5 ng mL–1 is within of 14–190 ng mL–1. The proposed method can be used for the cerium determination in the presence of many rare earths. Sorption-luminescent method can be applied for determination of trace cerium ions in synthetic water solutions containing rare earth elements of the cerium group. The proposed analytical method gave recoveries from 95 to 98.3% and relative standard deviation from 4.1% to 6.7% determination of cerium. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new CAPh ligand and based on it Ln(III) tetrakis-complexes were synthesized. • The structures, thermal stability and spectroscopy of these compounds are discussed. • The f-f luminescence was observed for the Eu(III), Tb(III) and Yb(III) complexes. In continuation of the studies of new promising phosphors a new representative of carbacylamidophosphates (CAPhs) was synthesized and used as a ligand to obtain new lanthanides complexes (NEt 4)[LnL 4 ] (Ln = La, Y, Ce – Nd, Sm – Lu; L- = {C 6 H 3 (4-Cl-3-NO 2) CONPO(OCH 3) 2 }-). The structure of "free" ligand HL and complexes (NEt 4)[YbL 4 ] and (NEt 4)[LuL 4 ] were established by X-ray diffraction analysis. Dimethyl(4-chloro-3-nitrobenzoyl)amidophosphate has a dimeric structure. Dimers are formed by means of two hydrogen bonds of N H···O P type between two neighboring molecules. In the structure of the complexes the ligands are coordinated to the metal ion by the P O and C O groups of the chelate fragment forming six-membered not planar rings. In the crystal, the ligand and the complexes form numerous intermolecular contacts, including specific Cl···O intramolecular interaction. For the obtained compounds absorption, 1H NMR, and IR spectra were recorded and analyzed. Thermal gravimetric analysis and luminescence spectroscopy at 77 K and 298 K were used to characterize the obtained complexes. [ABSTRACT FROM AUTHOR]

The quaternary tungstates Li3Ba2RE3(WO4)8 (RE = La–Nd, Sm–Ho) were obtained by a ceramic synthesis route and were characterized by powder and single crystal X-ray diffraction. The structures of Li3Ba2Pr3(WO4)8 and Li3Ba2Tb3(WO4)8 were refined from single crystal diffractometer data: RbLiBi2(MoO4)4 type, space group C2/c, a = 528.57(2), b = 1292.39(6), c = 1934.80(10) pm, β = 91.522(4)°, 2151 F2 values, 108 parameters for Li3Ba2Pr3(WO4)8 and a = 520.54(2), b = 1272.03(6), c = 1918.85(10) pm, β = 91.948(4)°, 2020 F2 values, 108 variables for Li3Ba2Tb3(WO4)8. Striking polyhedral building units in these tungstates are WO4 tetrahedra and LiO6 octahedra, while the mixed occupied site and the barium atoms have higher coordination numbers, i.e. RE/Li@O8 and Ba@O10. In addition to the powder quality assessment by means of reflection spectroscopy, the synthesized samples were studied for their suitability as a scintillator material. Therefore, X-ray excited luminescence measurements where performed. Apart from Li3Ba2Ce3(WO4)8 and Li3Ba2Nd3(WO4)8, all compounds show strong emission under X-ray irradiation. Li3Ba2La3(WO4)8 and Li3Ba2Gd3(WO4)8 show blue CT luminescence caused by tungstate units, while the other samples show typical and multiple lines due to well known [Xe]4fn → [Xe]4fn transitions. [ABSTRACT FROM AUTHOR]

The structure and solid‐state luminescence properties of an EuIII compound with two different lanthanide sites, [Eu(μ‐O)5(OH)(H2O)2][Eu(DOTA)(H2O)]2 (DOTA is 1,4,7,10‐tetrazacyclododecane‐1,4,7,10‐tetraacetate, C16H24N4O8), were determined. The compound crystallizes in a laminar structure in the triclinic space group P, where the two sites are a free europium(III) ion and an [Eu(DOTA)(H2O)]− complex. The crystal structure was determined using complex data treatment due to nonmerohedral twinning. Experimental data sets were recorded with large redundancy and separated according to scattering domains in order to obtain a reliable structure. In the first site, the [Eu(DOTA)(H2O)]− complex was found to adopt a capped twisted square‐antiprismatic (cTSAP) conformation, where a capping water molecule increased the coordination number of the europium(III) site to nine (CN = 9). In the second site, the europium(III) ion was found to be coordinated by two water molecules, one hydroxide group and five oxide groups from neighbouring [Eu(DOTA)(H2O)]− complexes. The coordination geometry of this site was found to be a compressed square antiprism (SAP) and the coordination number of the europium(III) ion was found to be eight (CN = 8). A large increase in the rate constant of luminescence was observed for EuIII in [Eu(DOTA)(H2O)]− in solid‐state luminescence spectroscopy measurements compared to in solution, which led to investigations of single crystals in deuterated media to exclude additional effects of quenching. We conclude that the most probable cause of the decrease in the observed luminescence lifetimes is the high asymmetry of the coordination environment of [Eu(DOTA)(D2O)]− in the [Eu(μ‐O)5(OD)(D2O)2][Eu(DOTA)(D2O)]2 crystals. [ABSTRACT FROM AUTHOR]

Recently, using the Eu2+ → Mn2+ energy transfer strategy to explore new single-phase phosphors suitable for the near-ultraviolet (n-UV) region has become one of the major strategies in solid-state lighting applications. Therefore, a novel color-tunable K2BaCa(PO4)2 (KBCPO):[Eu2+,Si4+],Mn2+ phosphor was developed because of the preeminent thermal stability of luminescence of Eu2+-activated KBCPO. In this study, we first designed a [Eu2+, Si4+] → [K+, P5+] charge compensation strategy to optimize the luminescence properties of Eu2+ in the KBCPO matrix. In terms of the obtained KBCPO:[Eu2+,Si4+] phosphor, this charge compensation method on the one hand strengthens the emission of Eu2+, and on the other hand, it dramatically improves the thermal stability of luminescence. In particular, the emission intensity of the KBCPO:0.03[Eu2+,Si4+] sample at 548 K can reach 103% relative to that at the initial temperature of 298 K. Based on this charge compensation strategy, we finally obtained a new dual emission KBCPO:[Eu2+,Si4+],Mn2+ phosphor. The analysis of the luminescence properties indicates that the emission enhancement of Mn2+ in KBCPO:[Eu2+,Si4+],Mn2+ stems from the energy transfer of Eu2+ → Mn2+ with the mechanism of the electric dipole–dipole interaction when excited at 365 nm. In addition, KBCPO:[Eu2+,Si4+],Mn2+ also has excellent thermal stability and the emission color could be easily tuned from cyan to orange only by adjusting the Eu2+ doping level. These results confirm that the KBCPO:[Eu2+,Si4+],Mn2+ phosphor is a viable candidate for n-UV white light emitting diodes. [ABSTRACT FROM AUTHOR]

This work aims to fully analyze the luminescence spectra and time response properties of LYSO:Ce (Lu 2-2x Y 2x SiO 5 :Ce) scintillation crystals with different Y contents. The photoluminescence excitation (PLE) and emission (PL) spectra of Ce1 and Ce2 luminescence centers in LYSO:Ce crystals with different Y contents have been systematically examined. The shape of photoluminescence emission spectra and the contribution of the energy transfer process between Ce1 and Ce2 have been varied with the yttrium content in the crystal. Based on the photoluminescence and scintillation decay time measurements, a table has been shown to provide the relationship between the decay time and Y content in the crystal. Meanwhile, the afterglow measurements demonstrate the relationship between long-lived delay recombination processes and the free carrier traps existing in the bandgap, and the source of afterglow has been analyzed. [ABSTRACT FROM AUTHOR]

Using the luminescent properties of temperature‐sensitive paints (TSPs) to monitor temperature is a new type of temperature measurement technology. Herein, Na9[EuW10O36](EuW10) molecules were doped with non‐fluorescent rare earth metal ions (La3+ and Gd3+) to prepare Na9[EuxLa1‐xW10O36](EuxLa1‐xW10) and Na9[EuxGd1‐xW10O36](EuxGd1‐xW10) probe molecules. The doping of non‐fluorescent rare earth metal ions (La3+ and Gd3+) will not change the structure of the parent EuW10. As the relative content of La3+ ions increasing, the luminescent intensity of the EuxLa1‐xW10 series decreases non‐monotonically; as the relative content of Gd3+ ions increasing, the luminescent intensity of EuxGd1‐xW10 series decreases monotonically. Subsequently, EuxLa1‐xW10 and EuxGd1‐xW10 as probe molecules were added into methyl methacrylate (MMA) to obtain temperature‐sensitive paints via polymerization process. In the range of 50 °C to 100 °C, the maximum relative sensitivity of temperature‐sensitive paints EuW10/PMMA, Eu0.9La0.1W10/PMMA and Eu0.7Gd0.3W10/PMMA can reach 1.27 % °C−1, 1.43 % °C−1, 1.42 % °C−1, respectively. This study indicates that the temperature sensing characteristics can be enhanced by doping EuW10 with non‐fluorescent rare earth ions (La3+, Gd3+), which can be promising materials used in more areas with high‐precision temperature measurements. [ABSTRACT FROM AUTHOR]

We synthesized two series of dinuclear rare earth complexes [RE2L2(acac)2(H2O)2]·i-PrOH (RE = Y (1), Eu (2), Dy (3), Ho (4), Er (5) and Yb (6)) and Dy2(L2)2(acac)2(C2H5OH)2 (7) (H2L = pyridine-2-carboxylic acid [(2-hydroxy-3-methoxyphenyl)methylene]hydrazide, Hacac = acetylacetone). The static (dc) magnetic susceptibility shows that the weak ferromagnetic interaction exists in DyIII of 3 and 7. Furthermore, the study of magnetization dynamics manifests that 7 possesses an energy barrier of about 45 K at a zero dc field, while the energy barrier of 3 is 42.93 K under the applied 800 Oe dc field by using a solvent-controlled crystallization. Interestingly, the energy barrier of 7 could attain 80.39 K through deteriorating the QTM. Besides, near-infrared luminescence analysis shows that the ligands can work as effective sensitizing agents of 5 and 6. We observed the characteristic peaks of ErIII and YbIII ions, meanwhile, complex 5 has a potential application for optical systems because the maximum peak is located in the third telecommunication window about 1531 nm. [ABSTRACT FROM AUTHOR]

trans‐[Ln(NO3)2(Ph3AsO)4](NO3)2 (1) and mer‐[Ln(NO3)3(Ph3AsO)3] (2) complexes were prepared from Ln(NO3)3·xH2O and Ph3AsO in chloroform (Ln = Y, Sm, Eu, Tb, and Dy). Production of complexes 1 vs. 2 and solvent content was found to be highly dependent on crystallization solvent choice. Tb and Eu produced only 1, while the other Ln metals produced both 1 and 2. Solvent‐free, acetone‐, and methanol‐containing polymorph series were identified for complexes 1. Acetone/ether‐ and CH2Cl2‐containing polymorph series were identified for complexes 2. Luminescence measurements were performed on solvent‐free 1 (Ln = Y, Eu, Tb, and Dy) and 2 (Ln = Sm) at 78 K. Sensitized lanthanide emission bands via resonance energy transfer were observed in all cases, except the control (Ln = Y). The efficiency of this energy transfer process varies amongst the lanthanide metals studied and was rationalized using Latva's empirical rule and Density Functional Theory calculations. [ABSTRACT FROM AUTHOR]

• Lanthanide metal–organic frameworks can be used as luminescent sensing platforms. • Several mechanisms (quenching, turn-on...) can be exploited to lead to sensitive and selective sensors. • Promising examples of drug, biomarkers, temperature and pH sensing are presented. Lanthanide metal–organic frameworks (Ln-MOFs) have aroused increasing interest due to their highly effective luminescence from their constitutive metal ions, ligands, and/or the inserted or absorbed guests, enabling a good luminescence response in analysis. This review aims to present a thorough understanding of the design principles of Ln-MOFs and the associated detection mechanisms. Sensors utilizing Ln-MOFs are categorized into three distinctive classes, distinguished by diverse synthesis strategies: Monometallic lanthanide MOFs, MOFs with intrinsic dual-emission properties, and innovative Ln-MOFs composites. Within each section, we explain the design strategies employed and the associated corresponding merits. Additionally, the review concludes with a presentation of the numerous applications where Ln-MOFs based luminescent sensors had a significant impact. [ABSTRACT FROM AUTHOR]

A theoretical model that allows to predict, for the first time, the luminescence properties of a new phosphor (BaSnSi3O9:Eu2+) is presented. The predicted emission wavelength, 488 nm with a 64 nm bandwidth, was confirmed by subsequent experimental work. The method consists in a multi‐electron Hamiltonian parametrized from ab initio calculations. The luminescence properties of other similar compounds (i.e., BaHfSi3O9:Eu2+ and BaZrSi3O9:Eu2+), for which there is already experimental information, were also correctly reproduced. Designing luminescence: Computational methods and quantum mechanics are used to predict the properties of a brand‐new phosphor based on EuII. Our prediction is confirmed by successive experimental data. [ABSTRACT FROM AUTHOR]

The paper is concerned with the study of triboluminescence of lanthanide salts in an atmosphere of hydrocarbon gases (methane, its homologues, ethylene, and acetylene). The luminescence of *CH and/or *C 2 appeared after mechanochemical decomposition of these gases during tribodestruction of crystals was observed in all the gases. Injection of hydrocarbon gases suppressed the glow of *N 2 (a gas component in a triboluminescence spectrum of air). When heavier hydrocarbon gases were used, the triboluminescence spectra indicated that *C 2 emission predominated over the luminescence of a *CH radical. The intensity of *C 2 emission decreased with an increase in a hydrocarbon chain. The decomposition mechanism of hydrocarbon gases to form *CH and *C 2 during triboluminescence of lanthanide salts in the atmosphere of these gases is discussed. A similar decomposition mechanism of these gases in electric discharges is also discussed. The experimental spectra of the *C 2 (Swan bands) were used to calculate and to estimate some characteristics of the radiating medium. The vibrational temperatures T vib ~ 4000–5000 K calculated for different hydrocarbon gases exceeded the rotational one T rot ˂ 3000 K. This indicates that the working medium is a nonequilibrium plasma, in which the C 2 excitation occurs due to electron impact. In addition, it was assumed that the excitation could also be caused by collision with heavy particles, for example, hot gas molecules as a result of gas heating during a series of consecutive experiments. [ABSTRACT FROM AUTHOR]

Liquid exfoliated, atomically thin semiconducting transition metal dichalcogenides (TMDs), as inorganic equivalents of graphene, have attracted great interest due to their distinctive physical, optoelectronic, and chemical properties. Functionalization of 2D TMDs brings new prospects for applications in optoelectronics, quantum technologies, catalysis, and medicine. In this report, dual functionalization of 2D semiconducting 2 H-MoS2 nanosheets through simultaneous incorporation of magnetic and luminescent properties is demonstrated. A facile method is proposed for tuning the properties of the TDM semiconductors and accessing multimodal platforms, consisting in covalent grafting of lanthanide complexes onto the surface of 2D TMDs. Dual functionalization of liquid-exfoliated MoS2 nanosheets is demonstrated simultaneously with both europium (III) and gadolinium (III) complexes to form a colloidally stable luminescent (with millisecond lifetimes) and paramagnetic MoS2-based nanohybrid material. This work is the first example of transition metal dichalcogenide nanosheets functionalized with preformed lanthanide complexes. These findings open new prospects for covalent functionalization of TMDs with molecular species bearing specific functionalities as a means to tune the optoelectronic properties of the semiconductors, in order to create advanced materials and devices with a wide range of functionalities. [ABSTRACT FROM AUTHOR]

• A stable, highly selective and sensitive lanthanide sensor towards toxic pollutant of formaldehyde is designed. • The sensor was fabricated into uniform microspheres, and further molded into smart detection device of test paper for naked eye detection of formaldehyde. • The sensing mechanism is revealed by luminescence lifetimes comparison. Formaldehyde is toxic to human body and animals, thus sensing of low concention of formaldehyde is urgent. A new uniform luminescent and stable lanthanide microsphere of europium complex sensor (Eu-MTFBA) towards formaldehyde in water is developed. Single crystal analysis shows the microsphere has a one dimensional (1D) coordination polymer structure. The sensor was further molded into smart detection device of test paper, which is applied to detect formaldehyde through naked eyes. Furthermore, the sensing mechanism is also revealed by luminescence lifetimes measurement. A stable, highly selective and sensitive lanthanide sensor towards toxic pollutant of formaldehyde is designed. The sensor was fabricated into uniform microspheres, and further molded into smart detection device of test paper for naked eye detection of formaldehyde. The sensing mechanism is revealed by luminescence lifetimes comparison. [Display omitted] [ABSTRACT FROM AUTHOR]

Er3+-doped and Er3+,Yb3+-co-doped Gd 2 O 2 S are one of the most efficient upconversion (UC) materials available to date. However, preparing lanthanide oxysulfides can be challenging as it requires several hours of heating at>1000 °C in high power furnaces. Nonetheless, in designing a new synthesis technology for UC materials, one should consider that these systems suffer from defect quenching, responsible for significant optical energy losses. In this work, the microwave-assisted solid-state (MASS) synthesis was explored as an alternative to synthesize this class of materials, using two different starting compounds – lanthanide oxides (Ln 2 O 3) and hydroxycarbonates (Ln(OH)CO 3), where Ln3+: Gd, Er, Yb. Different Er3+,Yb3+ concentrations were investigated, and the Er3+ (5%) ,Yb3+ (5%) and Er3+ (1%) ,Yb3+ (10%) were shown to give the most intense UC output comparable to commercially available materials. Using Ln(OH)CO 3 instead of the more common Ln 2 O 3 for the MASS synthesis contributed to higher UC efficiencies and a more homogeneous Er3+ and especially Yb3+ distribution through the Gd 2 O 2 S lattice as verified by luminescence lifetime measurements. These high-quality materials were prepared in a simple two-step synthesis of 50 min and using a domestic microwave oven, leading to a remarkable decrease of 79% in processing time and 93% in energy consumption, making the MASS method suitable to be explored as an alternative synthesis methodology for high performance UC materials. • Efficient Gd 2 O 2 S-based upconversion materials prepared in a rapid (50 min) microwave-assisted solid-state (MASS) synthesis. • Best upconversion performance observed for co-doped materials, specifically for Er3+(5%),Yb3+(5%) and Er3+(1%),Yb3+(10%). • Lanthanide hydroxycarbonates proven to be best precursors over the oxides, leading to a 10-fold UC intensity increase. • Best MASS-prepared materials show 4-fold lower UC intensity compared to custom materials with same Er3+,Yb3+ concentrations. • MASS method - decrease of 79% in processing time and 93% in energy consumption compared to conventional solid-state methods. [ABSTRACT FROM AUTHOR]

The high temperature sensitivity of the luminescence emission of thermographic phosphor (TP) particles favours its utilization for the measurement of wall or gas temperatures in combustion devices. The present work focuses on the luminescence behavior and suitability of two lanthanide ion types (Tm and Dy) doped in a YAG host crystal for high temperature applications. The Dy:YAG is a well-known thermographic phosphor and is used here as a reference for the comparison with Tm:YAG TP. Additionally its dopant concentration is varied to improve its signal intensity for high temperature applications. For the studied thermographic phosphors phosphorescence spectra, intensity ratios and luminescence decay time are characterized for a wide temperature range up to 1573 K. [ABSTRACT FROM AUTHOR]

Europium metal-organic frameworks (Eu-MOFs) and terbium metal-organic frameworks (Tb-MOFs) incorporated side-by-side nanofibrous membrane (Eu//Tb SBS NFs) was successfully fabricated by electrospinning. Eu-MOFs or Tb-MOFs emitting red or green light, respectively, were adjusted on each side, and a luminescent sensor with yellow luminescence was prepared by adjusting the ratio of the two MOFs. Eu//Tb SBS NFs have high luminescence efficiency and show sequential changes in luminescence color (yellow-green-gray). To investigate whether it is possible to detect metal ions reliably in aqueous media, we evaluated the wettability of the samples by contact angle measurement and luminescence stability in different pH conditions. Eu//Tb SBS NFs showed selective detection of Fe3+ and Cu2+ in aqueous solutions containing various metal ions. The quenching effect constant (K s v ) for Fe3+ was calculated as 7.62 x 103 M−1 (the limit of detection = 1.6 x 10−7 M), indicating high sensitivity for Fe3+. The luminescence changes of the Eu//Tb SBS NFs resulting from the presence of the metal ions and varying concentrations of the targeted metal ions were confirmed with the naked eye. This is the first report of a nanofibrous membrane with a unique side-by-side structure designed as a luminescence switchable dual sensor for Fe3+ and Cu2+. The superiority of Eu//Tb SBS NFs as luminescent sensors is discussed in this paper. [Display omitted] • We propose a simple strategy to develop luminescence switchable SBS NFs dual sensor. • Eu- and Tb-MOFs emitting red or green light, respectively, were placed in each side of SBS NFs. • Yellow luminescence was prepared by adjusting the ratio of the Eu- and Tb-MOFs. • SBS NFs were used as dual sensor for Fe3+ and Cu2+ that can be judged by naked eyes. • We have also proposed the luminescence mechanism of SBS NFs for metal ion detection. [ABSTRACT FROM AUTHOR]

Developments of ratiometric bioprobes are highly appealing due to the superiority of their self-calibration capability for the quantitative biotracking. In this work, we designed and synthesized a novel lanthanide complex-based ratiometric luminescence probe, [4'-(2,4-dinitrophenyloxy)-2,2':6',2"-terpyridine-6,6"-diyl]bis(methylenenitrilo) tetrakis(acetate)-Eu3+/Tb3+ (NPTTA-Eu3+/Tb3+), for the specific recognition and quantitative time-gated luminescence detection of hydrogen sulfide (H2S) in aqueous and living cell samples. Due to the presence of the photoinduced electron transfer (PET) process from the terpyridine-Eu3+/Tb3+ moiety to 2,4-dinitrophenyl (DNP), the probe itself is weakly luminescent. In physiological pH aqueous media, the reaction of NPTTA-Eu3+/Tb3+ with H2S leads to the cleavage of DNP moiety from the probe molecule, which affords the deprotonated (4'-hydroxy-2,2':6',2"-terpyridine-6,6"-diyl)bis(methylenenitrilo) tetrakis(acetate)-Eu3+/Tb3+ and terminates the PET process. Meanwhile, the intensity of Tb3+ emission at 540 nm is remarkably increased, while that of the Eu3+ emission at 610 nm is slightly decreased. After the reaction, the intensity ratio of Tb3+ emission to Eu3+ emission, I540/I610, was ~220-fold increased, and the dose-dependent enhancement of I540/I610 showed a good linearity upon the increase of H2S concentration with a detection limit of 3.5 nM. This unique luminescence response allowed NPTTA-Eu3+/Tb3+ to be conveniently used as a ratiometric probe for the time-gated luminescence detection of H2S with I540/I610 as a signal. In addition, the applicability of the probe for the quantitative time-gated luminescence imaging of intracellular H2S in living cells was investigated. The results demonstrated the efficacy and advantage of the new probe for the time-gated luminescence cell imaging application. [ABSTRACT FROM AUTHOR]

Lanthanide ions, due to their unique photo-physical characteristics, have attracted considerable attention in recent years. Their long lifetimes, sharp, well-defined emission bands, and designable environmental sensitivity make them ideal for integration into switchable supramolecular assemblies where emission can report on local conformation and/or coupled energy levels (redox state). The immobilisation of lanthanide containing constructs on interfaces facilitates device integration, the fabrication of advanced sensory and molecular electronic platforms and presents a means by which conformational dynamics within molecular assemblies can be analysed. In this feature article we discuss the current and potential applications for lanthanide luminescence in supramolecular, switchable and surface bound architectures. [ABSTRACT FROM AUTHOR]

Rare earth-doped fluorides with strong up-conversion (UC) luminescence have attracted growing attention due to their potential applications in photonics and biological areas. However, current techniques to process these fluorides into thin films have not been sufficiently developed. Here, we report for the first time the preparation of NaYF4 thin film doped with Yb3+, and Tm3+ by electro-deposition and subsequent annealing. The as-deposited thin film was characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, differential thermal analysis and photoluminescence. Under excitation by a near infrared laser diode at 980 nm, the transparent NaYF4:Yb-Tm thin film exhibits bright visible upconversion luminescence from Tm3+ as a result of energy transfer from Yb3+. The results demonstrate that the electro-deposition process provides facile access to UC fluoride thin films which may have applications in photovoltaic devices. [ABSTRACT FROM AUTHOR]

Luminescent lanthanide labels (LLLs) and semiconductor quantum dots (QDs) are two very special classes of (at least partially) inorganic fluorophores, which provide unique properties for Förster resonance energy transfer (FRET). FRET is an energy-transfer process between an excited donor fluorophore and a ground-state acceptor fluorophore in close proximity (approximately 1-20 nm), and therefore it is extremely well suited for biosensing applications in optical spectroscopy and microscopy. Within this cogent review, we will outline the main photophysical advantages of LLLs and QDs and their special properties for FRET. We will then focus on some recent applications from the FRET biosensing literature using LLLs as donors and QDs as donors and acceptors in combination with several other fluorophores. Recent examples of combining LLLs and QDs for spectral and temporal multiplexing from single-step to multistep FRET demonstrate the versatile and powerful biosensing capabilities of this unique FRET pair. As this review is published in the Forum on Imaging and Sensing, we will also present some new results of our groups concerning LLL-based time-gated cellular imaging with optically trifunctional antibodies and LLL-to-QD FRET-based homogeneous sandwich immunoassays for the detection of carcinoembryonic antigen. [ABSTRACT FROM AUTHOR]

In order to deduce the molecular mechanisms of biological function, it is necessary to monitor changes in the subcellular location, activation, and interaction of proteins within living cells in real time. Förster resonance energy-transfer (FRET)-based biosensors that incorporate genetically encoded, fluorescent proteins permit high spatial resolution imaging of protein-protein interactions or protein conformational dynamics. However, a nonspecific fluorescence background often obscures small FRET signal changes, and intensity-based biosensor measurements require careful interpretation and several control experiments. These problems can be overcome by using lanthanide [Tb(III) or Eu(III)] complexes as donors and green fluorescent protein (GFP) or other conventional fluorophores as acceptors. Essential features of this approach are the long-lifetime (approximately milliseconds) luminescence of Tb(III) complexes and time-gated luminescence microscopy. This allows pulsed excitation, followed by a brief delay, which eliminates nonspecific fluorescence before the detection of Tb(III)-to-GFP emission. The challenges of intracellular delivery, selective protein labeling, and time-gated imaging of lanthanide luminescence are presented, and recent efforts to investigate the cellular uptake of lanthanide probes are reviewed. Data are presented showing that conjugation to arginine-rich, cell-penetrating peptides (CPPs) can be used as a general strategy for the cellular delivery of membrane-impermeable lanthanide complexes. A heterodimer of a luminescent Tb(III) complex, Lumi4, linked to trimethoprim and conjugated to nonaarginine via a reducible disulfide linker rapidly (10 min) translocates into the cytoplasm of Maden Darby canine kidney cells from the culture medium. With this reagent, the intracellular interaction between GFP fused to FK506 binding protein 12 (GFP-FKBP12) and the rapamycin binding domain of mTOR fused to Escherichia coli dihydrofolate reductase (FRB-eDHFR) were imaged at high signal-to-noise ratio with fast (1-3 s) image acquisition using a time-gated luminescence microscope. The data reviewed and presented here show that lanthanide biosensors enable fast, sensitive, and technically simple imaging of protein-protein interactions in live cells. [ABSTRACT FROM AUTHOR]

Two stable three-dimensional lanthanide metal-organic frameworks, Ln-MOFs of [M 2 O(BDCPO) 1.5 (H 2 O) 7 ]·2H 2 O (Eu for CUST-621, Tb for CUST-622) are successfully constructed using π-electron riched ligand N,N′-bis(2,4-dicarboxyphenyl)-oxalamide (H 6 BDCPO) and Eu and Tb metal ions under solvothermal conditions. The appropriate chromophores in ligands can effectively sensitize Ln3+ ions, resulting in luminescence emission. The crystal structures are determined by single X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, infrared spectrophotometer and luminescence measurements. Triple emission centers are successfully designed and realized the solid-state white light (SSWL) performance, whose CIE coordinates are close to ideal white light (0.32, 0.33). Furthermore, the temperature sensitivity tests indicate that the two materials can be used to sense the temperature in the range of 303–423 K with remarkable color change. The maximum sensitivity are 6.86% K−1 and 7.73% K−1 at 423 K, respectively. Moreover, CUST-621 and CUST-622 can be used as multi-responsive luminescence sensors to Fe3+ and Cr 2 O 7 2−, with high sensitivity, long-time stability and remarkable selectivity with resistance to interference from other ions. This work supply a general way to construct Ln-MOFs materials for multifunctional luminescence properties for sensing fields. Eu-MOF and Tb-MOF are used as fluorescence sensors to detect Fe3+ and Cr 2 O 7 2− in the water environment. The different mass ratios of Eu and Tb are mixed to achieve white light emission. The temperature-sensitive performance experiment were carried out at 303K–423K. The maximum sensitivity of Eu-MOF and Tb-MOF are 6.86% K−1 and 7.73% K−1 at 423 K, respectively. The color of the doped system changes significantly with the change of temperature. [Display omitted] • Two isostructural Ln-based MOFs were constructed by π-conjugate system ligands onto its skeleton. • Adjusting the different mass ratios of Eu and Tb achieve the white light emission. • CUST-621 and CUST-622 display excellent temperature sensing performance. • The two fluorescent sensor can detect the analytes in a water environment. [ABSTRACT FROM AUTHOR]

Time-resolved luminescence measurements of luminescent lanthanide complexes have advantages in biological assays and , owing to their high sensitivity. In spite of the recent advances in their energy-transfer mechanism and molecular-orbital-based computational molecular design, it is still difficult to estimate the quantum yields of new luminescent lanthanide complexes. Herein, solid-phase libraries of luminescent lanthanide complexes were prepared through amide-condensation and Pd-catalyzed and their luminescent properties were screened with a microplate reader. Good correlation was observed between the time-resolved luminescence intensities of the solid-phase libraries and those of the corresponding complexes that were synthesized by using liquid-phase chemistry. This method enabled the rapid and efficient development of new sensitizers for SmIII, EuIII, and TbIII luminescence. Thus, solid-phase combinatorial synthesis combined with on-resin screening led to the discovery of a wide variety of luminescent sensitizers. [ABSTRACT FROM AUTHOR]

β-NaYF4:Ln3+ (Ln = Eu, Tb, Yb/Er, Yb/Tm) hexagonal microrods have been successfully synthesized through a facile molten salt method without any surfactant. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, high-resolution transmission electron microscopy, and photoluminescence spectra were used to characterize the samples. It is found that at a preferred reaction temperature of 400 °C, the structure of β-NaYF4 can gradually transform from microtubes to microrods as reaction time extends from 0.5 to 4 h. Furthermore, as the molar ratio of NaF:RE3+ (RE represents the total amount of Y3+ and the doped rare earth elements such as Eu3+, Tb3+, Yb3+/Er3+, or Yb3+/Tm3+) increased, the phase of sample transforms from YF3 into NaYF4. Under the excitation of 395 nm ultraviolet light, β-NaYF4:5 %Eu3+ shows the emission lines of Eu3+ corresponding to 5D0-3 → 7FJ ( J = 1-4) transitions from 400 to 700 nm, resulting in red down-conversion (DC) light emission. When doped with 5 % Tb3+ ions, the strong DC fluorescence corresponding to 5D4 → 7FJ ( J = 6, 5, 4, 3) transitions with 5D4 → 7FJ (green emission at 544 nm) being the most prominent group that has been observed. Moreover, upon 980 nm laser diode excitation, the Yb3+/Er3+- and Yb3+,Tm3+- co-doped β-NaYF4 samples exhibit bright yellow and blue upconversion (UC) luminescence, respectively, by two- or three-photon UC process. The luminescence mechanisms for the doped lanthanide ions were thoroughly analyzed. [ABSTRACT FROM AUTHOR]

Abstract: A novel N-heterocycle multicarboxylate ligand 4-(3,5-dicarboxyphenyl)pyridine-2,6-dicarboxylic acid (H4dpda) was synthesized, and then reacted with lanthanide salts to yield a series of lanthanide metal–organic frameworks, [Ln(Hdpda)(H2O)4]·0.5(H2O) (Ln=Eu(1), Gd(2), Tb(3), Dy(4)) and [Tb1− x Eu x (Hdpda)(H2O)4]·0.5(H2O) (x =0.1–10mol%). Single crystal X-ray diffraction and powder XRD patterns confirm these MOFs are isostructural. Luminescent measurements suggest that the ligand can provide efficient sensitization for the lanthanide ion Tb(III) and Eu(III) in the mixed lanthanide MOFs. Additionally, the luminescence color of the mixed MOFs can be easily tuned from green to green–yellow, yellow, orange, red–orange and red by varying the molar ratio of Eu(III)/Tb(III). [Copyright &y& Elsevier]

A systematic investigation of the luminescence properties of Dy3+ doped alkali-alkaline earth orthoborates of the stoichiometric composition XZBO 3 with X = Li, Na, K and Z = Mg, Ca, Ba was conducted. XRD diffractograms show that the compounds LiMgBO 3 , LiCaBO 3 , LiBaBO 3 , NaMgBO 3 , NaCaBO 3 , NaBaBO 3 , and KMgBO 3 could be produced in high purity. Relatively intense luminescence was observed only for the phases LiCaBO 3 , NaMgBO 3 , NaCaBO 3 and NaBaBO 3. Micro Raman investigations show that the Dy3+ luminesence mainly originates from the orthoborate phase in these samples. Photo-luminescence spectroscopy of LiCaBO 3 , NaCaBO 3 and NaBaBO 3 shows the typical Dy3+ emission with the prominent emission peak in the yellow spectral range around 575 nm. A second, but much less intense peak is observed at around 485 nm (cyan). The luminescence emission spectrum of Dy3+:NaMgBO 3 is much different: here, the highest emission intensity is observed at about 485 nm. It is proposed that the Dy3+ ions occupy the Na positions in this crystal phase which has a much higher symmetry than the alkaline earth positions in the other examined crystal phases. This is supported by broadened and more split up peaks in the excitation and emission spectra of Dy3+:NaMgBO 3 suggesting a much stronger local crystal field at the rare earth position in this compound. The results are additionally compared to spectroscopic data of different well known Dy3+ doped crystalline compounds and Dy3+ and Eu3+ doped alkali-alkaline earth orthoborates from other publications, which offer further insight into the relation between the crystallographic sites of the doped rare earth ions and their luminescence. • Alkali-alkaline earth orthoborates of the stoichiometric composition XZBO 3 with X = Li, Na, K and Z = Mg, Ca, Ba were doped with Dy3+. • Incorporation of Dy3+ into LiCaBO 3 , NaCaBO 3 , NaBaBO 3 , NaMgBO 3 is supported by simultaneous Micro Raman - Luminescence measurements. Incorporation of Dy3+ into LiMgBO 3 , LiBaBO 3 , KMgBO 3 is unlikely. • Dy3+ luminescence is correlated with the site symmetry of the Dy position in the crystal lattices. • The yellow Dy3+ emission intensity is decreased and the blue Dy3+ emission increased by a high symmetry at the rare earth position. [ABSTRACT FROM AUTHOR]

A series of neutral mononuclear lanthanide complexes [Ln(HL)2(NO3)3] (Ln = La, Ce, Nd, Eu, Gd, Dy, Ho) with rigid bidentate ligand, HL (4′-(1H-imidazol-1-yl)biphenyl-4-carboxylic acid) were synthesized under solvothermal conditions. The coordination compounds have been characterized by infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. According to X-ray diffraction, all the complexes are a series of isostructural compounds crystallized in the P2/n monoclinic space group. Additionally, solid-state luminescence measurements of all complexes show that [Eu(HL)2(NO3)3] complex displays the characteristic emission peaks of Eu(III) ion at 593, 597, 615, and 651 nm. [ABSTRACT FROM AUTHOR]

The three Dy 2 complexes based on schiff-base ligand H 2 L display various slow magnetic relaxation behaviors through utilizing different β -diketone co-ligands. [Display omitted] • A new schiff-base ligand was induced to construct Ln 2 complexes. • Three Dy 2 complexes display different magnetism for the tuning of β-diketonate coligands. • Complexes 4 and 5 exhibit characteristic near-infrared luminescent peaks of central ions. Seven new dinuclear lanthanide complexes based on a schiff-base ligand H 2 L and β-diketonate coligands have been synthesized and characterized: [Eu 2 (acac) 4 (HL) 2 ]·3C 2 H 5 OH (1), [Ln 2 (acac) 2 (HL) 4 ]·6C 2 H 5 OH (Ln = Tb(2), Dy(3), Er(4), Yb(5)), [Dy 2 (bfa) 4 (HL) 2 ]·2H 2 O (6), [Dy 2 (tmhd) 2 (HL) 4 ] (7) (H 2 L = 5-methylsalicylaldehyde-2-aminobenzoylhydrazone; Hacac = acetylacetone; Hbfa = benzoyltrifluoroacetylacetone; Htmhd = 2,2,6,6-tetramethylheptane-3,5-dione). These complexes are all centrosymmetric and bridged by phenoxo-O, offered with Ln 2 O 2 cores. Meanwhile, the near-infrared luminescence measurements show that the characteristic emission peaks of ErIII (4) and YbIII (5) ions can be observed, which means the effective sensitization of the ligands. Subsequently, the dynamic magnetization properties studies show that 3 , 6 and 7 exhibit slow magnetic relaxation behavior, typical SMM behavior, resulting in an effective barrier of 48.42 K (3) and 54.82 K (6) under an applied 800 Oe dc field, and 60.59 K for 7 under 3000 Oe dc field. In particular, this work demonstrates that the magnetic properties can be modulated by regulating the electron effects of terminal substituents on the coligands. [ABSTRACT FROM AUTHOR]

Three novel lanthanide complexes with the ligand 4,4-difluoro-1-(1,5-dimethyl-1H-pyrazol-4-yl)butane-1,3-dione (HL), namely [LnL3(H2O)2], Ln = Eu, Gd and Tb, were synthesized, and, according to single-crystal X-ray diffraction, are isostructural. The photoluminescent properties of these compounds, as well as of three series of mixed metal complexes [EuxTb1-xL3(H2O)2] (EuxTb1-xL3), [EuxGd1-xL3(H2O)2] (EuxGd1-xL3), and [GdxTb1-xL3(H2O)2] (GdxTb1-xL3), were studied. The EuxTb1-xL3 complexes exhibit the simultaneous emission of both Eu3+ and Tb3+ ions, and the luminescence color rapidly changes from green to red upon introducing even a small fraction of Eu3+. A detailed analysis of the luminescence decay made it possible to determine the observed radiative lifetimes of Tb3+ and Eu3+ and estimate the rate of excitation energy transfer between these ions. For this task, a simple approximation function was proposed. The values of the energy transfer rates determined independently from the luminescence decays of terbium(III) and europium(III) ions show a good correlation. [ABSTRACT FROM AUTHOR]

Two DO3A-type ligands conjugated to substrates of urokinase (L3) and caspase-3 (L4) via a propyl-amide linker were synthesized and their lanthanide(III) (Ln3+) complexes studied. A model compound without peptide substrate (L2) and an amine derivative ligand mimicking the state after enzymatic cleavage (L1) were also prepared. Proton Nuclear Magnetic Relaxation Dispersion (NMRD) profiles recorded on the gadolinium(III) (Gd3+) complexes, complemented with the assessment of hydration numbers via luminescence lifetime measurements on the Eu3+ analogues, allowed us to characterize the lanthanide coordination sphere in the chelates. These data suggest that the potential donor groups of the peptide side chains (carboxylate, amine) interfere in metal coordination, leading to non-hydrated LnL3 and LnL4 complexes. Nevertheless, GdL3 and GdL4 retain a relatively high relaxivity due to an important second-sphere contribution generated by the strongly hydrophilic peptide chain. Weak PARACEST effects are detected for the amine-derivative EuL1 and NdL1 chelates. Unfortunately, the GdL3 and GdL4 complexes are not significantly converted by the enzymes. The lack of enzymatic recognition of these complexes can likely be explained by the participation of donor groups from the peptide side chain in metal coordination. [ABSTRACT FROM AUTHOR]

Heterometallic complexes were used in rational design of luminescent isostructural MOF series with total preserving of initial {M 2 Ln} node. [Display omitted] • Heterometallic molecular complexes were used as building block sources for 5 new MOFs design. • Four new heterometallic isostructural MOFs were obtained and characterized with SCXRD, PXRD, IR and Luminescence analysis. • For the first time the total preserving of {M 2 Ln} node during the MOF structure formation was shown. • Rational design of luminescent MOFs based on heterometallic {M 2 Ln} complexes. The use of heterometallic pivalate complexes [M 2 Ln(piv) 7 (H 2 O) 2 ] (M = Zn2+, Cd2+; Ln = Eu3+, Tb3+; piv– = pivalate anion) as sources of heterometallic sites in the reaction with 1,4-naphthalenedicarboxylic acid (H 2 ndc) makes it possible to fully preserve the geometry of the building block in the structure of the obtained metal–organic organic frameworks (MOFs). Solvothermal synthesis in dimethylformamide (DMF) results in a series of isostructural layered MOFs (Me 2 NH 2)[M 2 Ln(dmf) 2 (ndc) 4 ]·DMF. The structure of the MOF (Me 2 NH 2)[Cd 2 Tb(dmf) 2 (ndc) 4 ]·DMF was determined by the means of single crystal X-ray diffraction analysis. Compounds based on europium cations show characteristic luminescence in the red region, while compounds based on terbium cations do not exhibit characteristic green luminescent properties and have ligand-centered emission. The reactions of [Cd 2 Eu(piv) 7 (H 2 O) 2 ] under similar conditions with 2,5-furandicarboxylic acid (H 2 fdc) are complicated, with complete destruction of the heterometallic fragment. The composition and structure of the homometallic MOF (Me 2 NH 2) 2 [Cd(fdc) 2 ]·DMF·H 2 O obtained in such conditions were determined by single crystal X-ray diffraction performed using synchrotron radiation. [ABSTRACT FROM AUTHOR]

By utilizing multicolor upconversion luminescence of rare earth-doped nanophosphors (UCNPs), NIR-light-activated photopolymerization and controlled drug delivery is achieved for PEGDA hydrogels. The loading capacity of zinc(ii) phthalocyanine reaches 12.3% into UCNPs–PEGDA hybrid microspheres. [ABSTRACT FROM AUTHOR]

• Two novel Metal complexes Gd-DO3AM-MPP and Eu-DO3AM-MPP for MRI studies of 5-HT 1A receptors were synthesized. • CEST Parameters 1) Residence Lifetime of water molecule (τ m) 0.23 ms 2) Relaxivity (r 1 = 5.85 mM−1s−1 and r 2 = 6.41 mM−1s−1) 3) Metal coordinated water molecule distance (r M -H2O) of 2.7 Å have been calculated. • Energy minimization through DFT and Theoretical docking Studies of Gd-DO3AM with 5-HT 1A receptor reflects the potential of Gd-DO3AM-MPP to bind with 5-HT 1A receptors. • Eu-DO3AM-MPP displays high affinity toward the 5-HT 1A receptors with K d value 62 ± 0.02 pM. • In vivo studies confirmed preferential binding of Gd-DO3AM-MPP to 5-HT 1A receptors in hippocampus region of the brain. Contrast enhancement in MRI using magnetization or saturation transfer techniques promises better sensitivity, and faster acquisition compared to T 1 or T 2 contrast. This work reports the synthesis and evaluation of 5-HT 1A targeted PARACEST MRI contrast agent using 1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide (DO3AM) as the bifunctional chelator, and 5-HT 1A -antagonist methoxyphenyl piperazine (MPP) as a targeting unit. The multi-step synthesis led to the MPP conjugated DO3AM with 60% yield. CEST-related physicochemical parameters were evaluated after loading DO3AM-MPP with paramagnetic MRI active lanthanides: Gadolinium (Gd-DO3AM-MPP) and Europium (Eu-DO3AM-MPP). Luminescence lifetime measurements with Eu-DO3AM-MPP and computational DFT studies using Gd-DO3AM-MPP revealed the coordination of one water molecule (q = 1.43) with metal-water distance (r M -H 2 O) of 2.7 Å and water residence time (τ m) of 0.23 ms. The dissociation constant of K d 62 ± 0.02 pM as evaluated from fluorescence quenching of 5-HT 1A (protein) and docking score of −4.81 in theoretical evaluation reflect the binding potential of the complex Gd-DO3AM-MPP with the receptor 5-HT 1A. Insights of the docked pose reflect the importance of NH 2 (amide) and aromatic ring in Gd-DO3AM-MPP while interacting with Ser 374 and Phe 370 in the antagonist binding pocket of 5-HT 1A. Gd-DO3AM-MPP shows longitudinal relaxivity 5.85 mM−1s−1 with a water residence lifetime of 0.93 ms in hippocampal homogenate containing 5-HT 1A. The potentiometric titration of DO3AM-MPP showed strong selectivity for Gd3+ over physiological metal ions such as Zn2+ and Cu2+. The in vitro and in vivo studies confirmed the minimal cytotoxicity and presential binding of Gd-DO3AM-MPP with 5-HT 1A receptor in the hippocampus region of the mice. Summarizing, the complex Gd-DO3AM-MPP can have a potential for CEST imaging of 5-HT 1A receptors. [ABSTRACT FROM AUTHOR]

The surface plasmon resonance (SPR) effect induced by metal nanoparticles (NPs) can improve the visible-light response in photocatalysis. However, the optical shielding effect of NPs will scatter light, which reduces the utilization of light. With unique 4 f electrons and multiple splitting of 4f orbits, lanthanide elements possess distinct luminescence property. Moreover, semiconductor can be excited by the role of up or down-conversion luminescence in rare earth. In this work, Yb with different contents were first doped in BiOBr via solvothermal method. Then, Pd NPs were deposited on Yb/BiOBr by photo-deposition. XRD, SEM, TEM, FT-IR, XPS, PL and Uv–vis-DRS were used to characterize the physical and optical structure of samples. The influence of Yb doping on the density of states (DOS) of BiOBr was analyzed by first principle calculation. The results show that the crystallinity and band-gap energy of BiOBr were promoted by Yb doping. Moreover, Yb doping promoted the exposure of active crystal face, which benefits the formation of Schottky junction after Pd deposition. The down-conversion luminescence of Yb can restrain the optical shielding effect and promote the SPR effect of Pd in photocatalysis. Image 1 • Yb doping enhances the crystallinity of BiOBr nanosheet. • Yb doping benefits the exposure of crystal face and the Schottky junction. • The luminescence induced by Yb3+/Yb2+ promotes the SPR effect of Pd. [ABSTRACT FROM AUTHOR]

• Gd3+, Tb3+ and Dy3+ ions doped borate host glasses have been prepared successfully. • Gd3+ glass shows ultraviolet radiation emission in the range of 310–315 nm. • Tb3+ and Dy3+ glasses can find applications in the green and yellow emission range. This paper reports the time-resolved luminescence and excitation-emission matrix measurements of three different lanthanide ions Gadolinium, Gd3+ (GdG), Terbium, Tb3+ (TbG) and Dysprosium, Dy3+(DyG) doped silver-zinc borate glasses. The GdG and TbG glasses were excited at 267 nm and 371 nm, respectively, and time-resolved luminescence measurements used to evaluate how the randomness of the network can influence the lanthanide ion emission. The GdG glass exhibited ultraviolet radiation (UVR) at around 310 nm with a 6P 7/2 → 8S 7/2 transition. Similarly, a sharp band at 545 nm with a 5D 4 → 7F 5 transition provided a bright green coloured emission from the TbG glass. To further elucidate the Dy3+ emission, steady-state luminescence (SSL), excitation-emission matrix (EEM) studies and decay associated spectra (DAS) were obtained. These showed a bright yellow emission transition (4F 7/2 → 6H 9/2), 571 nm composed of species with decay times of 0.062, 0.148, 0.337 and 0.701 ms. Among them, an ideal decay time was observed at 0.701 ms along with a dependency of the DyG glass lifetimes on the emission intensity. [ABSTRACT FROM AUTHOR]

In this study, single phase Dy x La 1-x BO 3 , Dy x Ce y La 1-x-y BO 3 , Dy x Eu y La 1-x-y BO 3 , and Tb x Ce y La 1-x-y BO 3 phosphors were successfully synthesized through the microwave assisted solid state method with urea. Synthesized compounds were characterized by X-Ray Diffraction, Fourier Transform Infrared spectroscopy, Scanning Electron Microscope, and Fluorescence spectroscopy. Thermal stabilities of the phosphors were studied with temperature dependent fluorescence measurements. In addition, density functional theory calculations were performed to investigate preferential Dy3+ ion doping sites in LaBO 3 lattice. The findings of the study revealed over ten times increase in the emission intensities of phosphors were observed with Ce3+ codoping. The highest luminescence intensities were recorded for Dy 0.09 Ce 0.05 La 0.86 BO 3 and Tb 0.07 Ce 0.05 La 0.88 BO 3 phosphors. Furthermore, energy transfers were supported by luminescence lifetime measurements. Temperature dependent fluorescence measurements showed their thermal stabilities. According to the CIE 1931 color space, the colors of the Dy3+ only doped, Ce3+/Dy3+; Ce3+/Tb3+ and Dy3+/Eu3+ codoped phosphors were determined as off-white, white, green and yellow-orange, respectively. Intensities of the bands and the colors of the phosphors can be tuned with the choice of codopant ions or with adjustments in their concentration ratio. • Microwave assisted solid state synthesis method saves energy and time. • Colors of LaBO 3 phosphors can be tuned by changing concentration of codopants. • Luminescence intensities of phosphors were significantly enhanced with codoping. • Rare earth codoped single phase LaBO 3 are candidates for solid state lighting. • Dy3+ only doped phosphors retain 86% of their luminescence intensity at 423 K. [ABSTRACT FROM AUTHOR]

New PdII–LnIII–PdII complexes of hexadentate N2O4 Schiff base ligand (H4L: N,N′-bis(2,3-dihydroxybenzylidene)-1,3-diamino-2,2-dimethylpropane) with Eu (1), Tb (2), Er (3) and Yb (4) ([Pd2Eu(H2L)2NO3](NO3)2∙2H2O∙2CH3OH 1, [Pd2Ln(H2L)2H2O](NO3)3∙3H2O, where Ln = Tb 2, Er 3, [Pd2Yb(H2L)2H2O](NO3)3∙5.5H2O 4) were synthesized and characterized structurally and physicochemically by thermogravimetry (TG), differential thermogravimetry (DTG), differential scanning calorimetry (DSC) and luminescence measurements. The compounds 1–4 are built of cationic heterometallic PdII–LnIII–PdII trinuclear units. The palladium(II) centers adopt a planar square geometry occupying the smaller N2O2 cavity of the Schiff base ligand. The lanthanide(III) is surrounded by two Schiff base ligands (eight oxygen atoms) and its coordination sphere is supplemented by a chelating bidentate nitrate ion in 1 or by a water molecule in 2–4. The complexes have a bent conformation along the PdII–LnIII–PdII line with valence angles in the ranges of 162–171°. The decomposition process of the complexes results in mixtures of: PdO, Pd and respective lanthanide oxides Eu2O3, Tb2O3, Tb4O7, Er2O3, Yb2O3. The luminescent measurements show low efficiency intramolecular energy transfer only in the complex of terbium(III) (2). [ABSTRACT FROM AUTHOR]