Lanthanide-Based Luminescent Hybrid Materials

A novel spectrofluorimetric method using optical sensor Eu3+-ACAC as a highly selective photo probe to determine Pregabalin in biological samples and pharmaceutical form

A novel spectrofluorimetric method with high selectivity and sensitivity was created to determine Pregabalin (PG) in pharmaceutical form, human serum, and urine. This method relies on detecting quenching in the intensity of luminescence of the europium acetylacetone complex (Eu3+-ACAC) at emission wavelength λem = 616 nm, which results from interaction with various concentrations of PG after excitation at λex = 395 nm and pH 6.5 in dimethylformamide (DMF). The calibration curve was generated using concentrations ranging from 7.6 × 10-8 to 6.3 × 10-6 mol/L. The plot showed a high correlation coefficient (r2) of 0.994 with a detection limit (LOD) of 2.81 × 10-8 mol/L and a quantification limit (LOQ) of 8.5 × 10-8 mol/L. The remarkable luminescence intensity quenching of the Eu3+-ACAC by ranged concentrations of PG was effectively employed as a photo probe to determine PG in marketable form and different body fluids. Spectroscopic characterization, such as absorption and emission spectra, confirmed the obtained sensor. The improved method is verified using a range of characteristics, such as accuracy, precision, selectivity, linearity, and robustness.

Effect of Pyrrolidinedithiocarbamate Ligand on the Luminescence Properties of Heteroligand Samarium and Europium Complexes: Experimental and Theoretical Study

The photophysical properties of two isostructural heteroligand lanthanide complexes of general formula Ln(pdtc)3(phen) (pdtc = pyrrolidinedithiocarbamate anion, phen = 1,10-phenanthroline), Ln = Sm3+ (1), Eu3+ (2)) were studied in solid state and dichloromethane (DCM) solution. The two lanthanide complexes were investigated by experimental techniques for structural (single-crystal X-ray diffraction analysis of 1, powder XRD, TG-DTA) and spectroscopic [electron paramagnetic resonance (EPR), infrared (IR), ultraviolet-visible (UV-vis), photoluminescence (PL)] characterization. DFT/TDDFT/ωB97xD and multireference SA-CASSCF/NEVPT2 calculations with perturbative spin-orbit coupling corrections were applied to construct the Jablonski energy diagrams and to discuss the excited state energy transfer mechanism with competing excited state processes and possible sensitized mechanism of metal-centered emission. The first excited state (S1) involved in the excited state energy transfer L(antenna)-to-Ln was predicted to have interligand (pdtc-to-phen) charge transfer character in contrast to the previously predicted ligand-to-metal charge transfer character. The theoretical consideration showed similar relaxation paths and luminescence quenching channels and appropriate Donor*(phen)-Acceptor*(Ln3+) energy gap for 1 and 2. The experimental measurements in the solid state, however, showed efficient luminescence and good ability to convert UV to visible light only for the Sm(pdtc)3(phen) complex. The minor emission of 2 was explained by partial reduction of Eu3+, confirmed by EPR and calculated electron density distribution data.

Dual-Mode Hydrogels with Structural and Fluorescent Colors toward Multistage Secure Information Encryption

Constructing an anti-counterfeiting material with non-interference dual optical modes is an effective way to improve information security. However, it remains challenging to achieve multistage secure information encryption due to the limited stimulus responsiveness and color tunability of the current dual-mode materials. Herein, a dual-mode hydrogel with both independently tunable structural and fluorescent colors toward multistage information encryption, is reported. In this hydrogel system, the rigid lamellar structure of poly(dodecylglyceryl itaconate) (pDGI) formed by shear flow-induced self-assembly provides the restricted domains wherein monomers undergo polymerization to form a hydrogel network, producing structural color. The introduction of fluorescent monomer 6-acrylamidopicolinate (6APA) as a complexation site provides the possibility of fluorescent color formation. The hydrogel's angle-dependent structural color can be controlled by adjusting the crosslinking density and water content. Additionally, the fluorescence color can be modulated by adjusting the ratio of lanthanide ions. Information of dual-mode can be displayed separately in different channels and synergistically overlayed to read the ultimate message. Thus, a multistage information encryption system based on this hydrogel is devised through the programed decryption process. This strategy holds tremendous potential as a platform for encrypting and safeguarding valuable and authentic information in the field of anti-counterfeiting.

Highly-sensitive optical thermometer developed based on an intervalence charge transfer mashup

Optical thermometers based on lanthanide thermal-coupled levels have attracted great attention owing to its fundamental importance in the fields of public health, biology, and integrated circuit. However, the inherent structural properties (shielded effect on 4f configurations, intense non-radiation relaxation) strictly suppress the sensing performance, limiting the relative temperature sensitivity (SR). To circumvent these limitations, we propose an intervalence charge transfer mashup strategy by inducing d0 electron configured transition metals. Specifically, transition metals Ta5+ is incorporated in Tm3+/Eu3+:LiNbO3, which improves the SR from 5.30 to 11.16% K-1. The validity of this component-modulation behavior is observed on other oxide crystals (NaY(Mo1-zWzO4)2) as well. Furthermore, the observed regulation is well explained by DFT calculation that indicates the d-orbit component at valence band minimum remains the core factor governing the electron transfer process. We successfully relate the SR to the band structure of luminescence carrier, offering a novel perspective for the collocation design of lanthanide configurations.

Phosphine Oxide-Nd3+ Coordination Chains with Cumulated Output Enable Efficient LED-Pumping Optical Amplification

Near-infrared luminescent rare-earth organic complexes have attracted intensive attention in the field of optical waveguide amplification. However, their optical gains were commonly less than 4 dB/cm due to limited doping concentrations. Herein, two one-dimensional (1D) Nd3+ coordination chains, namely, [Nd(TTA)3(DBTDPO)]n (Nd1) and [Nd(TTA)3(DPEPO)]n (Nd2), bridged by phosphine oxide ligands were developed for the neodymium-doped waveguide amplifier. Despite its P-P distance being similar to DBTDPO, the different P═O orientation of DPEPO renders markedly shorter intra- and interchain Nd-Nd distances for Nd2 in comparison to Nd1. Furthermore, the weaker intermolecular interactions alleviate the quenching effect for Nd2. Therefore, Nd2 can provide more locally concentrated and radiative Nd3+ ions, leading to a larger Nd3+-characteristic 1.06 μm emission intensity and duration than Nd1. Based on embedded and evanescent-field waveguide structures, Nd2 achieves state-of-the-art gain maxima of 5.7 and 4.9 dB/cm as well as outstanding gain stability. These results indicate that controllable coordination assembly of lanthanide ions in multidimension provides a flexible approach to combine local high-density outputs and effective suppression of quenching.

Terpyridyl-Imidazole Based Ligand Coordinated to Ln(Hexafluoroacetyl acetonate)3 Core: Synthesis, Structural Characterization, Luminescence Properties, and Thermosensing Behaviors in Solution and PMMA Film

A new array of ternary lanthanide complexes of the form [Ln(hfa)3(tpy-HImzphen)] have been synthesized and thoroughly characterized wherein Ln = LaIII (1), EuIII (2), SmIII (3), and TbIII (4); hfa = hexafluoroacetylacetonate; and tpy-HImzphen = 2-(4-[2,2':6',2″]terpyridin-4'-yl-phenyl)-1H-phenanthro[9,10-d]imidazole. Incorporation of tpy-HImzphen onto the Ln-hfa moiety induced a bathochromic shift of the absorption window of the complexes into the visible region. Extensive investigations of the luminescence characteristics have been conducted both at RT and at 77 K to understand the deactivation pathways of the complexes. Both steady-state and time-resolved emission spectral behaviors indicate four distinctive behaviors upon incorporation of tpy-HImzphen onto the lanthanide core, viz., a huge red-shift of the ligand-centered peak for LaIII; almost complete energy transfer for EuIII; very little energy transfer for SmIII, while reverse energy transfer in the case of TbIII. In addition, the EuIII-complex exhibits its excellence in luminescence thermometry in the solution state as well as in poly(methyl methacrylate) (PMMA) thin films. The thermosensitive luminescence response in solution was further utilized to mimic set-reset flip-flop logic operation. A plausible energy transfer scheme has been devised to explain dissimilar luminescence behaviors in the complexes. The role of LMCT was also considered for the observed thermosensing property of the Eu(III) complex.

Highly Efficient and Thermally Durable Luminescence of 1D Eu3+ Coordination Polymers with Arsenic Bridging Ligands

In this work, bisarsine oxides were evaluated as novel bridging ligands, aiming to develop practical and efficient luminescent lanthanide coordination polymers. We have synthesized one-dimensional (1D) Eu3+ coordination polymers that incorporate bisarsine oxide bridging ligands and hexafluoroacetylacetonate anions. These polymers exhibited a denser packing of chains compared to analogous polymers bridged with bisphosphine oxides. The coordination polymers demonstrated exceptional thermal stability and substantial emission quantum yields. Additionally, the bisarsine oxides induced a pronounced polarization effect, facilitating a sensitive electric dipole transition that yields considerably narrow band red emission. Remarkably, the Eu3+ coordination polymers with bisarsine oxides maintained intense emission even at 550 K. A distinctive feature of these polymers is their heating-induced emission enhancement observed when the temperature was increased from 300 K to 400 K.

Effective photosensitized emission of a Tb(III) complex using a β-diketonate photosensitizer and an oxygen barrier system in a thermally populated triplet state

Photosensitizer design of luminescent terbium (Tb(III)) complexes with narrow bandwidths is important for advancing luminescent materials. In this study, we report an effective photosensitizer model in a thermally populated lowest excited triplet (T1) state during Tb(III) emission. The Tb(III) complex comprises a Tb(III) ion (serving as an emission center), hexafluoroacetylacetonates (acting as photosensitizer ligands), and bulky cyclohexyl group-attached phosphine-oxide-type ligands (functioning as an oxygen barrier system). Emission properties including emission and excitation spectra, ligand-excited emission quantum yields, and emission lifetimes were evaluated in the absence and presence of oxygen. Coordination geometry structures were determined through analysing single-crystal structures. The electronic structure based on 4f-orbitals was estimated from radiative rate constants and quantum chemical calculations. The bulky phosphine oxide ligand not only provides an oxygen barrier system but also induces an electronic structural modulation based on 4f-orbitals, allowing for effective photosensitized Tb(III) emission in a thermally populated ligand T1 state in air.

Cd(II)-based complex loaded with drug doxorubicin hydrogels against leukemia and reinforcement learning

A new 3D metal-organic frameworks [Cd6(L)4(bipy)3(H2O)2·H2O] (1) was gained by employing Cd(II) and organic ligand [H3L = 4,4',4''-(benzene-1,3,5-triyltris(oxy))tribenzoic acid)benzene acid; bipy = 4,4'-bipyridine] in the solvothermal condition, which has been fully examined via single-X ray diffraction, FTIR and elemental analysis and so on. Using natural polysaccharides hyaluronic acid (HA) and carboxymethyl chitosan (CMCS) as raw materials, we successfully prepared HA/CMCS hydrogels and observed their internal micromorphology by scanning electron microscopy. Using doxorubicin (Dox) as a drug model, we synthesized a novel metal gel particle loaded with doxorubicin, and their encapsulation and release effects were studied using fluorescence spectroscopy, followed by further investigation of their components through thermogravimetric analysis. Based on this, the therapeutic effect on leukemia was evaluated. Finally, an enhanced learning method for automatically designing new ligand structures from host ligands was proposed. Through generative modeling and molecular docking simulations, the biological behavior of the host and predicted cadmium complexes was extensively studied.

Finely manipulating room temperature phosphorescence by dynamic lanthanide coordination toward multi-level information security

Room temperature phosphorescence materials have garnered significant attention due to their unique optical properties and promising applications. However, it remains a great challenge to finely manipulate phosphorescent properties to achieve desirable phosphorescent performance on demand. Here, we show a feasible strategy to finely manipulate organic phosphorescent performance by introducing dynamic lanthanide coordination. The organic phosphors of terpyridine phenylboronic acids possessing excellent coordination ability are covalently embedded into a polyvinyl alcohol matrix, leading to ultralong organic room temperature phosphorescence with a lifetime of up to 0.629 s. Notably, such phosphorescent performance, including intensity and lifetime, can be well controlled by varying the lanthanide dopant. Relying on the excellent modulable performance of these lanthanide-manipulated phosphorescence films, multi-level information encryption including attacker-misleading and spatial-time-resolved applications is successfully demonstrated with greatly improved security level. This work opens an avenue for finely manipulating phosphorescent properties to meet versatile uses in optical applications.

Boosting the Luminescence of a Europium(III)-β-Diketonate Complex-Nanoclay Aqueous Solution by Acetylcholine

It is a challenging task to prepare lanthanide complex-based luminescent materials with high quantum efficiency in aqueous solution, since the excited state of Ln3+ can be significantly quenched by water through the excitation of the O-H vibrations. Herein, we present a simple and environmentally friendly strategy to prepare strongly red-light-emitting lanthanide complex-based luminescent materials by loading 2-thenoyltrifluoroacetate (TTA) on the Eu3+-exchanged nanoclay (Eu3+(TTAn)-NC, NC = nanoclay) and coadsorption of choline chloride (ChCl) or acetylcholine chloride (AChCl) in water. The coadsorbed molecules remarkably boosted the luminescence of Eu3+(TTAn)-NC, which is tentatively ascribed to the removal of waters coordinated in the Eu3+ coordination sphere via the complete coordination of TTA mediated by ChCl or AChCl. Highly luminescent films were facilely prepared by mixing a Eu3+(TTAn)-NC aqueous solution with PVA-ChCl (PVA-AChCl) deep eutectic solvents. This work provides a simple and environmentally friendly way for preparing highly luminescent emitting luminescent materials in aqueous solution.

A combined experimental-molecular modeling study of crown ether europium complexes: Effects of the coordinated anion on structural and luminescence properties

It is reported the synthesis, characterization by elemental analysis, thermogravimetry; electronic absorption, infrared, excitation, and emission spectroscopies of the [Eu(12C4)(phen)2(X)n]X2 complexes, where 12C4 = 12-crown-4, phen = 1,10-phenanthroline, and X  = F-, Cl-, Br-, SCN-, ClO4-, and NO3-. It is verified that the polarizability of the anion X- exerts remarkable effects on the emission process. As a general trend, lower wavenumbers for the 7F0→5L6, 7F0→5D2 and 7F0→5D1 transitions are associated with the anions with higher volumes and, consequently, higher polarizability. The molecular modeling results performed with quantum methods (RHF and DFT) suggest some relationships between the calculated structures, electronic, and luminescence properties with the presence of the LMCT (ligand-to-metal charge transfer) states, which explains the differences in the emission spectra of these complexes due to the coordinated anion.

Luminescent lanthanide-containing gelatin/polydextran/laponite nanocomposite double-network hydrogels for processing and sensing applications

Lanthanide-containing nanomaterials have gained significant popularity for their utilization in polymeric networks, enabling the creation of luminescent nanocomposites for advanced applications. In this study, we developed a new type of lanthanide-containing nanocomposite hydrogels by incorporating terbium-containing laponite (Tb3+@Lap) into the networks of polyethyleneimine-modified gelatin/polydextran aldehyde (PG/PDA) through dynamic bonds. The structures and properties of the Tb3+@Lap-containing nanocomposite double-network (ncDN) hydrogels were comprehensively investigated in comparison with the DN hydrogels with a pure polymeric network and the Lap-containing ncDN hydrogels. The PG/PDA/Tb3+@Lap ncDN hydrogels with multiple dynamic bonds (i.e., imine bonds, coordination bonds, hydrogen bonds, and electrostatic interactions) exhibited remarkable characteristics of shear-thinning and self-healing, making them suitable for the construction of hydrogel scaffolds on a macroscale using fabrication techniques such as electrospinning and 3D printing. Moreover, the PG/PDA/Tb3+@Lap ncDN hydrogels have been demonstrated to act as sensitive and selective luminescent sensors for detecting copper ions. Taken together, a versatile lanthanide-containing ncDN hydrogel platform capable of dynamic features is developed for processing and sensing applications.

Crystal structure of tetra-phenyl phosphate tetra-kis-[dimethyl (2,2,2-tri-chloro-acet-yl)phos-pho-ramidato]lutetium(III), PPh4[LuL4]

A lutetium(III) complex based on the anion of the ligand dimethyl (2,2,2-tri-chloro-acet-yl)phospho-ramidate (HL) and tetra-phenylphosphonium, of composition PPh4[LuL 4] (L = CAPh = carbacyl-amido-phosphate), or (C24H20)[Lu(C4H6Cl3NO4P)4], has been synthesized and structurally characterized. The X-ray diffraction study of the compound revealed that the lutetium ion is surrounded by four bis-chelating CAPh ligands, forming the complex anion [LuL 4]- with a coordination number of 8[O] for LuIII, while PPh4 + serves as a counter-ion. The coordination geometry around the Lu3+ ion was determined to be a nearly perfect triangular dodeca-hedron. The complex crystallizes in the monoclinic crystal system, space group P21/c, with four mol-ecules in the unit cell. Weak hydrogen bonds O⋯HC(Ph), Cl⋯HC(Ph) and N⋯HC(Ph) are formed between the cations and anions. For a comparative study, HL-based structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed. A Hirshfeld surface analysis was also performed.

Design, Characterization, and Bioanalytical Applications of Green Terbium- and Nitrogen-Doped Carbon Quantum Dots as a Fluorescent Nanoprobe for Omadacycline Analysis

Terbium- and nitrogen-doped carbon quantum dots (Tb,N@CQDs) were greenly created employing microwave synthesis from plum juice with terbium nitrate. The synthesis of Tb,N@CQDs was fast (7 min) with a high quantum yield (35.44%). Tb,N@CQDs were fully characterized using transmission electron microscopy, Zeta potential analysis, fluorescence, and ultraviolet spectroscopy. Omadacycline (OMC) is a broad-spectrum tetracycline that has been recently approved by the United States Food and Drug Act (FDA) in October 2018. OMC is the first oral aminomethylcycline class antibiotic drug that was authorized for the treatment of acute skin structure infections and community-acquired pneumonia. Tb,N@CQDs exhibited emission at 440 nm after excitation at 360 nm, where their fluorescence intensity showed a reduction upon addition of OMC. The experimental parameters were further studied and optimized. The linear range was between 40 and 60 parts per billion (ppb), with (limit of quantitation) equal to 34.78 ppb. The proposed approach was validated for bioanalytical purposes using FDA guidelines and proved to be straightforward, cheap, highly sensitive, and very selective, which can be used in clinical studies. The developed approach proved to be green using some current assessment metrics and was applied successfully for the determination of OMC in human plasma, milk, and pharmaceutical formulations as well as pharmacokinetic study.

Recent advances in lanthanide-based POMs for photoluminescent applications

Since the first formation of the famous "Peacock-Weakley" anions [Ln(W5O18)2]8/9-, a steady stream of breakthroughs have been made in the chemistry of multitalented lanthanide (Ln)-based polyoxometalates (POMs) for their potentially desirable properties. In particular, LnIII ions are generally recognised as the "vitamins of the modern industry" owing to their ability to cover a wide emission range, endowing Ln-based POMs with great potential for versatile and diverse luminescence-related applications. In this frontier, we discuss the synthesis strategies and intramolecular energy transfer in Ln-based POM derivatives. Then, the progressive improvements achieved with Ln-based POMs in photoluminescence applications are highlighted, focusing mainly on luminescent and fluorescent probes. Finally, the challenges for Ln-based POM materials for photoluminescence applications are discussed.

Rationally designed nanotrap structures for efficient separation of rare earth elements over a single step

Extracting rare earth elements (REEs) from wastewater is essential for the growth and an eco-friendly sustainable economy. However, it is a daunting challenge to separate individual rare earth elements by their subtle differences. To overcome this difficulty, we report a unique REE nanotrap that features dense uncoordinated carboxyl groups and triazole N atoms in a two-fold interpenetrated metal-organic framework (named NCU-1). Notably, the synergistic effect of suitable pore sizes and REE nanotraps in NCU-1 is highly responsive to the size variation of rare-earth ions and shows high selectivity toward light REE. As a proof of concept, Pr/Lu and Nd/Er are used as binary models, which give a high separation factor of SFPr/Lu = 796 and SFNd/Er = 273, demonstrating highly efficient separation over a single step. This ability achieves efficient and selective extraction and separation of REEs from mine tailings, establishing this platform as an important advance for sustainable obtaining high-purity REEs.

Photophysics and its application in photon upconversion

Photoluminescence (PL) upconversion is a phenomenon involving light-matter interaction, where the energy of the emitted photons is higher than that of the incident photons. PL upconversion has promising applications in optoelectronic devices, displays, photovoltaics, imaging, diagnosis and treatment. In this review, we summarize the mechanism of PL upconversion and ultrafast PL physical processes. In particular, we highlight the advances in laser cooling, biological imaging, volumetric displays and photonics.

Molecularly Targeted Lanthanide Nanoparticles for Cancer Theranostic Applications

Injectable colloidal solutions of lanthanide oxides (nanoparticles between 10 and 100 nm in size) have demonstrated high biocompatibility and no toxicity when the nanoparticulate units are functionalized with specific biomolecules that molecularly target various proteins in the tumor microenvironment. Among the proteins successfully targeted by functionalized lanthanide nanoparticles are folic receptors, fibroblast activation protein (FAP), gastrin-releasing peptide receptor (GRP-R), prostate-specific membrane antigen (PSMA), and integrins associated with tumor neovasculature. Lutetium, samarium, europium, holmium, and terbium, either as lanthanide oxide nanoparticles or as nanoparticles doped with lanthanide ions, have demonstrated their theranostic potential through their ability to generate molecular images by magnetic resonance, nuclear, optical, or computed tomography imaging. Likewise, photodynamic therapy, targeted radiotherapy (neutron-activated nanoparticles), drug delivery guidance, and image-guided tumor therapy are some examples of their potential therapeutic applications. This review provides an overview of cancer theranostics based on lanthanide nanoparticles coated with specific peptides, ligands, and proteins targeting the tumor microenvironment.

Portable and Recyclable Luminescent Lanthanide Coordination Polymer Film Sensors for Adenosine Triphosphate in Urine

Adenosine triphosphate (ATP) is a small molecule that is released to the urine from bladder urothelial cells and the bladder mucosal band of the human body. In certain cases, ATP can serve as a biomarker in bladder disease. For the practical applicability of luminescent sensors for ATP in urine, it is significant to find a new strategy for making the detection progress simple and available for in-field urine analysis. Here, a novel luminescent lanthanide coordination polymer (Tb-BPA) was designed and synthesized for quick and sensitive detection of ATP through luminescence quenching with a quenching constant of 4.90 × 103 M-1 and a detection limit of 0.55 × 10-6 M. Besides, Tb-BPA has excellent anti-interference ability and can detect ATP in simulated urine with a small relative standard deviation (<4%). Moreover, the luminescent polyacrylonitrile nanofiber films modified by Tb-BPA were prepared by electrospinning and were used for ATP visual detection. Notably, this film is easy to recover and reuse, and maintains good detection performance after at least 7 cycles.

Construction of Highly Luminescent Lanthanide Coordination Polymers and Their Visualization for Luminescence Sensing

NaH2SIP was selected as an organic ligand (NaH2SIP = 5-sulfoisophthalic acid monosodium salt). We successfully constructed a new class of lanthanide coordination polymers Ln-HS ([Ln(SIP)(DMF)(H2O)4]DMF·H2O; Ln = Eu, Tb, Sm, and Dy) by a simple solvothermal synthesis method. They exhibited excellent photoluminescence properties for Ln3+ ions, where Eu-HS and Tb-HS exhibited high quantum yields of 13.70 and 42.38%, respectively. The codoped lanthanide coordination polymers obtained by doping with different ratios of Eu3+/Tb3+ serve as excellent ratiometric thermometers with high sensitivities in the physiological temperature range, with values of 16.8, 7.0, and 14.5%·K-1, respectively. The luminescent colors of Tb0.95Eu0.05-HS and Tb0.94Eu0.06-HS exhibit variations from green to yellow to orange, achieving visualized luminescence in a narrow temperature range. The composite film material Tb0.94Eu0.06-HS@PMMA demonstrates this color variation. Next, Tb0.5Sm0.5-HS obtained by Tb3+/Sm3+ codoping was investigated. The difference in the luminescence colors visible to the naked eye at different excitation wavelengths and the change in luminescence colors occur in a very narrow temperature range. All of them show the great value of the visualized luminescence in practical anticounterfeiting, with double anticounterfeiting function and high security.

Base-Directed Formation of Isostructural Lanthanide-Sulfate-Glutarate Coordination Polymers with Photoluminescence

A series of five isostructural 3D lanthanide-based coordination polymers [LnIII2(H2O)6(glu)(SO4)2]n [Ln = Pr(1), Nd(2), Sm(3), Eu(4), and Gd(5)] was effortlessly obtained within a few minutes via the microwave-heating method. The employment of auxiliary bases, that is, sodium hydroxide, 4,4'-bipyridine, and 1,4-diazabicyclo[2.2.2]octane, led to the formation of the title complex, whereas base-free synthesis yielded a three-dimensional inorganic coordination polymer, [Ln2(H2O)4(SO4)3]n·nH2O, Ln = Nd (2a). The robustness of the synthetic method was illustrated as both microwave-heating and conventional hydrothermal techniques also enabled the formation of a high-crystalline phase-pure complex 1-5. In the structure of 1-5, glutarato (glu2-) and sulfato ligands link dinuclear Ln(III) building units into three-dimensional frames. The glu2- ligands act as tethering linkers, expanding the structure into a neutral 3D coordination network. Hydrogen bonds were found to be the predominant intermolecular interactions in the crystal structures. Photoluminescence of the complex 1-5 was studied.

Tracking of structural defects induced by Eu-doping in β-Ag2MoO4: their influences on electrical properties

In this study, several methods were employed to investigate the electrical characteristics of β-Ag2MoO4 systems, both Eu-doped and undoped, synthesized using the microwave-assisted hydrothermal method. The focus extended to understanding how synthesis time influences material defects, with doping fixed at 1%. A systematic shift in the silver vacancy (VAg) concentration was observed within the doped β-Ag2MoO4 system. Specifically, this study demonstrated that the incorporation of Eu3+ into polycrystalline β-Ag2MoO4 initially increases the VAg concentration. However, as the synthesis time progresses, the VAg concentration decreases, resulting in alterations in the resulting electrical properties, arising from the intricate interplay between the number of grain boundaries and carrier density. By combining information obtained from photoluminescence, positron annihilation lifetime spectroscopy, and impedance spectroscopy, a comprehensive conduction mechanism was formulated, shedding light on both doped and undoped β-Ag2MoO4 systems.

Influence of Ancillary Ligand on the Photosensitization and Photophysical Properties of Red Luminescent Tri-fluorinated Β-diketonate Eu(III) Complexes

Highly emissive ternary Eu(III) complexes were synthesized with a tri-fluorinated β-diketone as principal ligand and heterocyclic aromatic compounds as ancillary ligands to assess their utility as an illuminating material for display devices and other optoelectronics. The general characterizations, regarding the coordinating facets of complexes were accomplished via various spectroscopic techniques. Thermal stability was investigated via TGA/DTA. Photophysical analysis was accomplished by PL studies, Band gap value, color parameters and J-O analysis. DFT calculations were performed adopting geometrically optimized structure of complexes. Superb thermal stability has been achieved in complexes, which decides their concrete candidature for display devices. The bright red luminescence of complexes is ascribed to 5D0 → 7F2 transition of Eu(III) ion. Colorimetric parameters unlocked the applicability of complexes as warm light source and J-O parameters adequately summarized the coordinating surrounding around the metal ion. Various radiative properties were also evaluated which suggested the prospective use of complexes in lasers and other optoelectronic devices. The band gap and Urbach band tail, procured from absorption spectra, revealed the semiconducting behavior of synthesized complexes. DFT studies rendered the energies of FMO and various other molecular parameters. It can be summarized from the photophysical and optical analysis of synthesized complexes that these complexes are virtuous luminescent materials and possess potentiality to be used in diverse domain of display devices.

Triboluminescence and crystal structure of the complex [Eu(MBA)3 Dipy]2 (HMBA)

The atomic structure of the crystals [Eu(MBA)3 Dipy]2 (HMBA) (MBA-аnion toluic acid, Dipy-2,2'-dipyridyl, HMBA-toluic acid), displaying intensive luminescence and triboluminescence was determined using single crystal X-ray diffraction analysis. The triclinic centrosymmetric crystals have the following parameters: a = 10.620(2), b = 11.849(2), c = 14.9868(2) Å, α = 68.297(1), β = 76.172(1), γ = 80.378(1)°, sp.gr. P - 1, Z = 1, ρcalc.  = 1.537 g/cm3 . The structure belongs to the insular type and is presented as the isolated complex Eu2 -dimeric formations and outer-sphere HMBA. The structural aspects of the observed luminescence and triboluminescence properties of the compound were discussed, and the cleavage plane role in the process of the crystal destruction was revealed.

Synthesis of CdSe Quantum Dots in Two Solvents of Different Boiling Points for Polymer Optical Fiber Technology

Polymer materials find many applications in various industries. Efforts are being made to obtain structures with increasingly better properties. It is necessary not only to obtain new materials but also to modify existing structures. Such is the situation with polymer optical fibers. The widespread use of polymer optical fibers is impossible, due to their very high optical losses compared to glass optical fibers. The solution to this problem can be the manufacturing of polymer active optical fibers. Active fibers are the basic components of fiber optic amplifiers and lasers that allow the direct amplification of light inside the fiber. In order for their operation to be the most effective, it is necessary to use dopants. The most commonly used are lanthanide ions isolated from the polymer network, active organic dyes, and quantum dots. These dopants are characterized by very high luminescence and long glow times. Quantum dots of CdSe are made using two organic solvents that differ in boiling points-hexane (a low-boiling solvent with a boiling point of 69 °C) and 1-octadecene (a high-boiling solvent with a boiling point of 315 °C). This work aims to test whether the type of solvent used to obtain quantum dots affects the doping capabilities of polymer structures, from which optical fibers can then be drawn.

Modulating the Photoluminescence of Europium through Crystalline Assembly Formation with Gold Nanoclusters and Then Phosphate Ions

We report delayed fluorescence enhancement of europium (Eu3+) ions through complexation with ligand-stabilized gold nanoclusters (Au NCs). The different Eu3+-centric emissions following complexation with Au NCs exhibited selective augmentation in the spectral lines attributed to the 5D0 → 7FJ transitions. The photoluminescence (PL) properties, including delayed Eu emission, from each component could be modulated through further functionalization of phosphate ions (Pi), leading to crystallization. The assembled crystalline structure of europium-containing Au NCs (Eu Au NCs) was corroborated by selected area electron diffraction analyses and high-resolution transmission electron microscopy analyses. On the basis of PL measurements and other experimental evidence, the two different lifetimes arising from the components, prompt emission of Au NCs and delayed emission of Eu3+, were affected in the assembled nanostructure. Such a design offers the possibility of developing an optical system by conjugating molecular NCs and atomic luminescent probes that has potential uses.

Comparative spectroscopic study of Tb:Ce(Sal)3Phen complex inhibited PVA nanofibres for flexible moisture sensor

In the present work, we report a systematic study on optical alteration in Tb:Ce(Sal)3Phen, Tb(Sal)3Phen complexes, and TbCl3·6H2O inhibited in polyvinyl alcohol (PVA) polymeric nanofibres. We also report the feasibility of Tb:Ce(Sal)3Phen complex dispersed electrospun nanofibres for opto-humidity sensor. Structural, morphological, and spectroscopic properties of the synthesized nanofibres were systematically compared using Fourier transform infrared spectroscopy, scanning electron microscopy, and Photoluminescence analysis. Synthesized Tb(Sal)3Phen complex inhibited in nanofibres yields characteristic bright green photoluminescence of Tb3+ under UV excitations, which is at least two manifolds enhanced on the addition of Ce3+ ions in the same complex. The presence of Ce3+ ions, the salicylate ligand, and the Tb3+ ion help to expand the absorption range (290 nm-400 nm) and, subsequently, the photoluminescence in blue and green regions. Our analysis revealed the linear enhancement of photoluminescence intensity with the addition of Ce3+ ions. Upon exposing the flexible Tb:Ce(Sal)3Phen complex dispersed nanofibres mat in different humidity environments, photoluminescence intensity shows a linear variation. The prepared nanofibres film shows good reversibility, small hysteresis, cyclic stability, and acceptable response and recovery times i.e. 35 and 45 s. The humidity sensing mechanism was proposed on the basis of infrared absorption analysis of dry and humid nanofibres.

Near Infrared Emissive Lanthanide Luminescence Nanoparticle Used in Early Diagnosis and Brain Temperature Detection for Ischemic Stroke

Ischemic stroke (IS) is one of the most dangerous medical conditions resulting in high mortality and morbidity. The increased brain temperature after IS is closely related to prognosis, making it highly significant for the early diagnosis and the progression evaluation of IS. Herein, a temperature-responsive near infrared (NIR) emissive lanthanide luminescence nanoparticle is developed for the early diagnosis and brain temperature detection of IS. After intravenous injection, the nanoparticles can pass through the damaged blood-brain barrier of the ischemic region, allowing the extravasation and enrichment of nanoparticles into the ischemic brain tissue. The NIR luminescence signals of the nanoparticles are used not only to judge the location and severity of the cerebral ischemic injury but also to report the brain temperature variation in the ischemic area through a visualized way. The results show that the designed nanoparticles can be used for the early diagnosis of ischemic stroke and minimally invasive temperature detection of cerebral ischemic tissues in transient middle cerebral artery occlusion mice model, which is expected to make the clinical diagnosis of ischemic stroke more rapid and convenient, more accurately evaluate the state of brain injury in stroke patients and also guide stroke hypothermia treatment.

A novel optical temperature sensor and energy transfer properties based on Tb3+/Sm3+ codoped SrY2(MoO4)4 phosphors

A series of SrY2(MoO4)4 phosphors doped and co-doped with Tb3+/Sm3+ ions was synthesized to develop new optical temperature sensor materials. The structures, morphologies, and luminescent characteristics of these phosphors were thoroughly investigated. Luminescence spectra of mono-doped SrY2(MoO4)4 phosphors were measured under the excitation at 375 and 403 nm corresponding to direct excitation of Tb3+ and Sm3+, respectively. The characteristic luminescence bands corresponding to electronic transitions of terbium and samarium ions were detected and investigated for different dopant concentrations. The emission spectrum of the Tb3+/Sm3+ co-doped sample exhibited a total of five distinct emission peaks, indicating an energy transfer from Tb3+ to Sm3+ ions. The energy transfer efficiency from Tb3+ ions to Sm3+ ions was investigated in detail. At elevated temperatures, Tb3+ and Sm3+ exhibited distinct thermal sensitivities in their emission and excitation spectra, leading to evident thermochromic behavior. The fluorescence intensity ratio (FIR) was utilized with dual center to evaluate the temperature sensitivity of SrY2(MoO4)4:Tb3+/Sm3+ phosphors. The temperature sensing mechanism relied on the emission band intensity ratios of the 4G5/2 → 6H5/2, 4G5/2 → 6H9/2, and 4G5/2 → 6H7/2 transitions of Sm3+ in conjunction with the 5D5/2 → 7F5/2 transitions of Tb3+. This approach demonstrated high thermal sensitivity values, reaching up to 0.9% K-1. The studied nanoparticles exhibited sub-degree thermal resolution, making them suitable candidates for precise temperature-sensing applications.

New Transition Metal Coordination Polymers Derived from 2-(3,5-Dicarboxyphenyl)-6-carboxybenzimidazole as Photocatalysts for Dye and Antibiotic Decomposition

Coordination polymers (CPs) are an assorted class of coordination complexes that are gaining attention for the safe and sustainable removal of organic dyes from wastewater discharge by either adsorption or photocatalytic degradation. Herein, three different coordination polymers with compositions [Ni(HL)(H2O)2·1.9H2O] (1), [Mn3(HL)(L)(μ3-OH)(H2O)(phen)2·2H2O] (2), and [Cd(HL)4(H2O)]·H2O (3) (H3L = 2-(3,5-dicarboxyphenyl)-6-carboxybenzimidazole; phen = 1,10-phenanthroline) have been synthesized and characterized spectroscopically and by single crystal X-ray diffraction. Single crystal X-ray diffraction results indicated that 1 forms a 2D layer-like framework, while 2 exhibits a 3-connected net with the Schläfli symbol of (44.6), and 3 displays a 3D supramolecular network in which two adjacent 2D layers are held by π···π interactions. All three compounds have been used as photocatalysts to catalyze the photodegradation of antibiotic dinitrozole (DTZ) and rhodamine B (RhB). The photocatalytic results suggested that the Mn-based CP 2 exhibited better photodecomposition of DTZ (91.1%) and RhB (95.0%) than the other two CPs in the time span of 45 min. The observed photocatalytic mechanisms have been addressed using Hirshfeld surface analyses.

Upconversion Luminescence in Mononuclear Yb/Sm Co-crystal Assemblies at Room Temperature

Metal-based upconversion luminescence transforming high-energy photons into low-energy photons is an attractive anti-Stokes shift process for fundamental research and promising applications. In this work, we developed the upconversion luminescence in co-crystal assemblies consisting of discrete mononuclear Yb and Sm complexes. The characteristic visible emissions of Sm3+ were observed under the excitation of absorption band of Yb3+ at 980 nm. A series of co-crystal assemblies were investigated based on mononuclear Yb and Sm complexes, and the strongest luminescence was obtained when the molar concentration between Yb3+ and Sm3+ is equivalent. The crystal structure was fully characterized by the single crystal X-ray diffraction and upconverting energy transfer mechanisms were verified as cooperative sensitization upconversion and energy transfer upconversion. This is the first example of Sm3+ -based upconverting luminescence in discrete lanthanide complexes which present as co-crystal assemblies at room temperature.

A Bifunctional Coordination-Chain-Based Hydrogen-Bonded Framework for Quantitative Enantioselective Sensing

Enantioselective sensing is highly crucial and challenging due to the highly similar physical/chemical properties of enantiomers which may have different chemical impact on organism. Luminescent coordination compounds have attracted great attention as sensing materials based on their controllable chemical and electric structures that can be highly matched with the targeted species. To achieve high-performance enantioselective sensing, the direct synthesis of chiral and luminescent bifunctional coordination compounds is a rational way but highly challenging due to the price and synthesis difficulty. Herein, an anionic coordination-chain-based hydrogen-bonded framework was applied as a host to accommodate chiral and luminescent centers via a facile cation exchange reaction, affording a bifunctional framework that possesses enantioselective sensing properties for the mixture of enantiomers. This study paves a pathway for constructing multifunctional coordination chain-based hydrogen-bonded frameworks for rapidly enantioselective sensing function.

Luminescent Hybrid BPA.DA-NVP@Eu2L3 Materials: In Situ Synthesis, Spectroscopic, Thermal, and Mechanical Characterization

A series of homogeneous hybrid BPA.DA-NVP@Eu2L3 materials were obtained through an in situ approach where the luminescent dopant was formed at the molecular level with different contents (0.1; 0.2; 0.5; 1; and 2% by weight). A Europium(III) complex (Eu2L3) with quinoline-2,4-dicarboxylic acid was applied as a luminescence additive while a polymer matrix consisted of a combination of bisphenol A diacrylate (BPA.DA) and N-vinylpyrrolidone (NVP) monomers. Synthesis steps and the final materials were monitored by NMR and Fourier transform infrared spectroscopy (FTIR). The emission, excitation spectra, lifetime, and quantum yield measurements were applied for the determination of the photophysical characteristics. The thermal and mechanical properties of the obtained materials were tested via thermal analysis methods (TG/DTG/DSC and TG-FTIR) in air and nitrogen atmospheres, dynamic mechanical analysis (DMA), and hardness and bending measurements. Generally, even a small addition of the metal complex component causes changes in the thermal, mechanical, and luminescent properties. Hybrid materials with a greater europium complex content are characterized by a lower stiffness and hardness while the heterogeneity and the flexibility of the samples increase. A very small amount of an Eu2L3 admixture (0.1% wt.) in a hybrid material causes an emission in the red spectral range and the luminescence intensity was reached for the BPA-DA-NVP@1%Eu2L3 material. These materials may be potentially used in chemical sensing, security systems, and protective coatings against UV.

Eu3+ Complex-Based Superhydrophobic Fluorescence Sensor for Cr(VI) Detection in Water

Cr(VI) compounds are bioaccumulative and highly toxic pollutants, and there is a need for simple and fast detection methods to monitor their trace levels. In this work, we developed a Eu3+ complex-based fluorescence sensor to easily detect Cr(VI) in water droplets. Our sensor consists of a nanofibrous membrane electrospun with a blend of polyvinylidene fluoride (PVDF), silica particles, and Eu3+ complex. Upon modifying the membrane surface with fluoroalkyl chemistry, the sensor displayed superhydrophobicity. When a water droplet with Cr(VI) was placed on such a superhydrophobic fluorescence sensor, the overlapping absorption of Cr(VI) and Eu3+ complex facilitated the inner filter effect, allowing the selective detection of Cr(VI) down to 0.44 µM (i.e., 45.76 µg L-1). We proposed and designed of new inexpensive and fast sensor for the detection of Cr(VI).

Exploration of Optical and Radiative Properties of Fluorinated β-keto Carboxylate Tb3+ Complexes Emanating Cool Green Light

Tb3+ complexes with β-ketocarboxylic acid as main ligand and heterocyclic systems as auxiliary ligand were synthesized and analyzed to assess their prospective relevance as green light emitting material. The complexes were characterized via various spectroscopic techniques and were found to be stable up to ≈ 200 ℃. Photoluminescent (PL) investigation was performed to assess the emissive nature of complexes. Longest luminescence time of decay (1.34 ms) and highest intrinsic quantum efficiency (63.05%) were fetched for complex T5. Color purity of complexes was found to be in range 97.1 - 99.8% which demonstrated the aptness of these complexes in green color display devices. NIR Absorption spectra were employed to evaluate Judd-Ofelt parameters to appraise the luminous performance and environment encircling Tb3+ ions. The JO parameters were found to follow the order: Ω2 > Ω4 > Ω6 and suggested the higher covalence character in complexes. Theoretical branching ratio in the range 65.32 - 72.68%, large stimulated emission cross section and narrow FWHM for 5D4 → 7F5 transition unlocked the relevance of these complexes as a green color laser media. Band gap and Urbach analysis were consummated via enforcing nonlinear curve fit function on absorption data. Two band gaps with values in between 2.02 - 2.93 eV established the prospective use of complexes in photovoltaic devices. Energies of HOMO and LUMO were estimated employing geometrically optimized structures of complexes. Investigation of biological properties accomplished via antioxidant and antimicrobial assays which communicated their applicability in biomedical domain.

Tough, Eu3+ -Induced Luminescent Hydrogel as Flexible Chemosensor for Real-Time Quantitative Detection of Zn2+ Ion

Herein, a novel tough luminescent hydrogel with Europium is fabricated using a facile copolymerization process by introducing 2,2':6',2-terpyridine (TPy) into a dual physical cross-linked hydrogel. The obtained P(NAGA-co-MAAc)/Eu/TPy (x) (x refers to the feed ratio of NAGA to MAAc) hydrogels not only show outstanding mechanical performances (fracture strength, ≈2.5 MPa), but also give a special ability of rapid detection to low concentrations of zinc ions. Attractively, the theoretical limits of detection (LOD) of the hydrogel sensors are calculated as 1.6 µm, which is acceptable within the WHO limit. Furthermore, the continuous change in fluorescence of P(NAGA-co-MAAc)/Eu/TPy (10) strips upon contact with Zn2+ can be clearly observed by the naked eyes with the aid of a portable UV lamp, resulting in semi-quantitative naked-eyes detection through a standard colorimetric card. Moreover, by identifying the RGB value of the hydrogel sensor, it can also realize quantitative analysis. Therefore, excellence in sensing, simplicity in structure, and convenience in using make P(NAGA-co-MAAc)/Eu/TPy (10) hydrogel as a superior fluorescent chemosensor of Zn2+ ions.

Rational Loading of Linear Multi-Site Receptors with Functional Lanthanide Containers: The Missing Link between Oligomers and Polymers

Although metal-containing organic polymers are becoming essential for modern applications in lighting, catalysis, and electronic devices, very little is known about their controlled metallic loading, which mainly limits their design to empirical mixing followed by characterization and often hampers rational developments. Focusing on the appealing optical and magnetic properties of 4f-block cations, the host-guest reactions leading to linear lanthanidopolymers already display some unexpected dependence of the binding-site affinities on the length of the organic polymer backbone: a drift usually, and erroneously, assigned to intersite cooperativity. Taking advantage of the parameters obtained for the stepwise thermodynamic loading of a series of rigid linear multi-tridentate organic receptors with increasing length, N = 1 (monomer L1), N = 2 (dimer L2), and N = 3 (trimer L3), with [Ln(hfa)3] containers in solution (Ln = trivalent lanthanide cations, hfa- = 1,1,1,5,5,5-hexafluoro-pentane-2,4-dione anion), it is demonstrated here that the site-binding model, based on the Potts-Ising approach, successfully predicts the binding properties of the novel soluble polymer P2N made up of nine successive binding units . An in-depth examination of the photophysical properties of these lanthanidopolymers shows impressive UV→vis downshifting quantum yields for the europium-based red luminescence, which can be modulated by the length of the polymeric chain.

Excitation Wavelength Engineering through Organic Linker Choice in Luminescent Atomic/Molecular Layer Deposited Lanthanide-Organic Thin Films

We demonstrate multiple roles for the organic linker in luminescent lanthanide-organic thin films grown with the strongly emerging atomic/molecular layer deposition technique. Besides rendering the hybrid thin film mechanically flexible and keeping the lanthanide nodes at a distance adequate to avoid concentration quenching, the organic moieties can act as efficient sensitizers for the lanthanide luminescence. We investigate six different aromatic organic precursors in combination with Eu3+ ions to reveal that by introducing different nitrogen species within the aromatic ring, it is possible to extend the excitation wavelength area from the UV range to the visible range. This opens new horizons for the application space of these efficiently photoluminescent thin-film materials.

Potassium and Cesium Fluorinated β-Diketonates: Effect of a Cation and Terminal Substituent on Structural and Thermal Properties

As potential precursors for the synthesis of fluoroperovskites, a family of heavy alkali metal (MI = K, Cs) fluorinated β-diketonates were prepared and characterized by elemental analysis, IR, and powder-XRD. The crystal structures of the new six complexes, MI(β-dikF)(H2O)X, X = 0 or 1, were also determined. The structural diversity of this poorly explored class of complexes was discussed, including the preferred types of cation polyhedra and the ligand coordination modes, and the thermal properties of the metal β-diketonates were studied by TG-DTA in an inert (He) atmosphere. The data obtained allowed us to reveal the effect of the metal cation and the terminal substituent on the structural and thermal features of this family of complexes.

Screening the complex biological behavior of late lanthanides through genome-wide interactions

Despite their similar physicochemical properties, recent studies have demonstrated that lanthanides can display different biological behaviors. Hence, the lanthanide series can be divided into three parts, namely early, mid, and late lanthanides, based on their interactions with biological systems. In particular, the late lanthanides demonstrate distinct, but poorly understood biological activity. In the current study, we employed genome-wide functional screening to help understand biological effects of exposure to Yb(III) and Lu(III), which were selected as representatives of the late lanthanides. As a model organism, we used Saccharomyces cerevisiae, since it shares many biological functions with humans. Analysis of the functional screening results indicated toxicity of late lanthanides is consistent with disruption of vesicle-mediated transport, and further supported a role for calcium transport processes and mitophagy in mitigating toxicity. Unexpectedly, our analysis suggested that late lanthanides target proteins with SH3 domains, which may underlie the observed toxicity. This study provides fundamental insights into the unique biological chemistry of late lanthanides, which may help devise new avenues toward the development of decorporation strategies and bio-inspired separation processes.

Exploring Ln(III)-Ion-Based Luminescent Species as Down-Shifters for Photovoltaic Solar Cells

In this work, we have compiled our research on lanthanide-based luminescent materials for use as down-shifter layers in photovoltaic (PV) mini-modules. The complexes we have prepared (C1-17), with formulas [Eu₂(phen)₂(bz)₆] (C1), [Eu₂(bphen)₂(bz)₆] (C2), [Eu(tta)₃bphen] (C3), [Eu(bta)₃pyz-phen] (C4), [Eu(tta)₃pyz-phen] (C5), [Eu(bta)₃me-phen] (C6), [Er(bta)₃me-phen] (C7), [Yb(bta)₃me-phen] (C8), [Gd(bta)₃me-phen] (C9), [Yb(bta)₃pyz-phen] (C10), [Er(tta)₃pyz-phen] (C11), [Eu₂(bz)₄(tta)₂(phen)₂] (C12), [Gd₂(bz)₄(tta)₂(phen)₂] (C13), [EuTb(bz)₄(tta)₂(phen)₂] (C14), [EuGd(bz)₄(tta)₂(phen)₂] (C15), [Eu_1.2Gd_0.8(bz)₄(tta)₂(phen)₂] (C16), and [Eu_1.6Gd_0.4(bz)₄(tta)₂(phen)₂] (C17), can be grouped into three families based on their composition: Complexes C1-6 were synthesized using Eu³⁺ ions and phenanthroline derivatives as the neutral ligands and fluorinated β-diketonates as the anionic ligands. Complexes C7-11 were prepared with ligands similar to those of complexes C1-6 but were synthesized with Er³⁺, Yb³⁺, or Gd³⁺ ions. Complexes C12-17 have the general formula [M1M2(bz)₄(tta)₂(phen)₂], where M1 and M2 can be Eu³⁺, Gd³⁺, or Tb³⁺ ions, and the ligands were benzoate (bz^-), 2-thenoyltrifluoroacetone (tta^-), and 1,10-phenanthroline (phen). Most of the complexes were characterized using X-ray techniques, and their photoluminescent properties were studied. We then assessed the impact of complexes in the C1-6 and C12-17 series on the EQE of PV mini-modules and examined the durability of one of the complexes (C6) in a climate chamber when embedded in PMMA and EVA films. This study emphasizes the methodology employed and the key findings, including enhanced mini-module efficiency. Additionally, we present promising results on the application of complex C6 in a bifacial solar cell.

[α-AsW9O33]9- bridged hexagonal clusters of Ln(III) showing field induced SMM behavior: experimental and theoretical insight

Polyoxometalates (POM), as inorganic polydentate oxygen donors, provide binding opportunities for oxophilic lanthanide metal centers to construct novel Ln-substituted POM materials with exciting structures and attractive properties. Herein, we have reported four arsenotungstate [α-AsW₉O₃₃]^9- based lanthanide-containing polyoxometalates [Cs_xK_36-x{Ln₆(H₂O)₁₂(α-AsW₉O₃₃)₆}]·yH₂O (Ln = Er (1), Gd (2), Ho (3), and Tb (4)), which are synthesized in an alkaline medium. Complexes 1-3 are the dimeric structures of [Ln₃(H₂O)₆(α-AsW₉O₃₃)₃]^18- polyanions, whereas complex 4 is a hexamer of the polyanion [Tb (H₂O)₂(α-AsW₉O₃₃)]^6- as a building unit. In all the complexes, [α-AsW₉O₃₃]^9- units are staggered up and down and give rise to the chair conformation, where one [α-AsW₉O₃₃]^9- unit bridges two Ln(III) centers through four μ₂-oxygen and two terminal oxygen atoms, resulting in the hexagonal arrangement of lanthanides. The dynamic magnetic measurement indicates that only complex 1 exhibits slow relaxation of magnetization with an applied dc field (1500 Oe). To gain insight into the slow relaxation of magnetization in complex 1, the ligand-field parameters and the splitting of the ground-state multiplet of the Er(III) ions have been estimated. The ab initio calculation results confirm that the ground state wave function of these molecules (1, 3, and 4) is mainly composed of a mixture of m_J states, and the non-axial crystal field (CF) terms are more predominant than the axial CF term. The solid-state fluorescence spectra of 1-4 reveal that the photoexcitation O → M ligand-to-metal charge-transfer (LMCT) of arsenotungstate fragments is effectively quenched due to the spatial coordination environment around the Ln(III) ion.

Paper-based biosensors relying on core biological immune scaffolds for the detection of procymidone in vegetables

In order to achieve a highly sensitive detection of procymidone in vegetables, three paper-based biosensors based on a core biological immune scaffold (CBIS) were developed, which were time-resolved fluorescence immunochromatography strips with Europium (III) oxide (Eu-TRFICS). Goat anti-mouse IgG and europium oxide time-resolved fluorescent microspheres formed secondary fluorescent probes. CBIS was formed by secondary fluorescent probes and procymidone monoclonal antibody (PCM-Ab). The first type of Eu-TRFICS (Eu-TRFICS-(1)) fixed secondary fluorescent probes on a conjugate pad, and PCM-Ab was mixed with a sample solution. The second type of Eu-TRFICS (Eu-TRFICS-(2)) fixed CBIS on the conjugate pad. The third type of Eu-TRFICS (Eu-TRFICS-(3)) was directly mixed CBIS with the sample solution. They solved the problems of steric hindrance of antibody labeling, insufficient exposure of antigen recognition region and easy loss of activity in traditional methods. They realized multi-dimensional labeling and directional coupling. They replaced the loss of antibody activity. And the three types of Eu-TRFICS were compared, among which Eu-TRFICS-(1) was the best detection choice. Antibody usage was reduced by 25% and sensitivity was increased by 3 times. Its detection range was 1-800 ng/mL, the limit of detection (LOD) was 0.12 ng/mL with the visible LOD (vLOD) of 5 ng/mL.

Two-photon excited luminescence of structural light enhancement in subwavelength SiO2 coating europium ion-doped paramagnetic gadolinium oxide nanoparticle and application for magnetic resonance imaging

BACKGROUND

Oxides of lanthanide rare-earth elements show great potential in the fields of imaging and therapeutics due to their unique electrical, optical and magnetic properties. Oxides of lanthanide-based nanoparticles enable high-resolution imaging of biological tissues by magnetic resonance imaging (MRI), computed tomography (CT) imaging, and fluorescence imaging. In addition, they can be used to detect, treat, and regulate diseases by fine-tuning their structure and function. It remains challenging to achieve safer, efficient, and more sensitive nanoparticles for clinical applications through the structural design of functional and nanostructured rare-earth materials.

RESULT

In this study, we designed a mesoporous silica-coated core-shell structure of europium oxide ions to obtain near-infrared two-photon excitation fluorescence while maintaining high contrast and resolution in MRI. We designed enhanced 800 nm photoexcitation nanostructures, which were simulated by the finite-difference method (FDM) and finite-difference time-domain method (FDTD). The nanoparticle structure, two-photon absorption, up-conversion fluorescence, magnetic properties, cytotoxicity, and MRI were investigated in vivo and in vitro. The nanoparticle has an extremely strong optical fluorescence response and multiple excitation peaks in the visible light band under the 405 nm continuous-wave laser excitation. The nanoparticle was found to possess typical optical nonlinearity induced by two-photon absorption by ultrafast laser Z-scan technique. Two-photon excited fluorescence of visible red light at wavelengths of 615 nm and 701 nm, respectively, under excitation of the more biocompatible near-infrared (pulsed laser at 800 nm). In an in vitro MRI study, a T1 relaxation rate of 6.24 mM^-1 s^-1 was observed. MRI in vivo showed that the nanoparticles could significantly enhance the signal intensity in liver tissue.

CONCLUSIONS

These results suggest that this sample has applied potential in visible light fluorescence imaging and MRI.

Construction of High Quantum Yield Lanthanide Luminescent MOF Platform by In Situ Doping and Its Temperature Sensing Performance

Lanthanide luminescent MOF materials show excellent luminescent properties. However, obtaining lanthanide luminescent MOFs with high quantum yield is a challenging research. A novel bismuth-based metal-organic framework [Bi(SIP)(DMF)₂] was constructed by solvothermal method, utilizing 5-sulfoisophthalic acid monosodium salt (NaH₂SIP) and Bi(NO₃)₃·5H₂O. Thereafter, doped MOFs (Ln-Bi-SIP, Ln = Eu, Tb, Sm, Dy, Yb, Nd, Er) with different luminescent properties have been obtained by in situ doping with different lanthanide metal ions, among which Eu-Bi-SIP, Tb-Bi-SIP, Sm-Bi-SIP, and Dy-Bi-SIP have high quantum yield. What is special is that the doping amount of Ln³⁺ ions is very low, and the doped MOF can achieve high luminescence quantum yields. EuTb-Bi-SIP obtained by Eu³⁺/Tb³⁺ codoping and Dy-Bi-SIP exhibit good temperature sensing performance over a wide temperature range with the maximum sensitivity S_r of 1.6%·K^-1 (433 K) and 2.6%·K^-1, respectively (133 K), while the cycling experiments also show good repeatability in the assay temperature range. Finally, considering the practical application value, EuTb-Bi-SIP was blended with an organic polymer poly(methyl methacrylate) (PMMA) to produce a thin film, which shows different color changes at different temperatures.

Novel Red-Emitting Eu3+-Doped Y2(WxMo1-xO4)3 Phosphor with High Conversion Efficiency for Lighting and Display Applications

In this study, a series of trivalent europium-doped tungstate and molybdate samples were synthesized using an improved sol-gel and high-temperature solid-state reaction method. The samples had different W/Mo ratios and were calcined at various temperatures ranging from 800 to 1000 °C. The effects of these variables on the crystal structure and photoluminescence characteristics of the samples were investigated. It was found that a doping concentration of 50% for europium yielded the best quantum efficiency based on previous research. The crystal structures were found to be dependent on the W/Mo ratio and calcination temperature. Samples with x ≤ 0.5 had a monoclinic lattice structure that did not change with calcination temperature. Samples with x > 0.75 had a tetragonal structure that remained unchanged with calcination temperature. However, samples with x = 0.75 had their crystal structure solely dependent on the calcination temperature. At 800-900 °C, the crystal structure was tetragonal, while at 1000 °C, it was monoclinic. Photoluminescence behavior was found to correlate with crystal structure and grain size. The tetragonal structure had significantly higher internal quantum efficiency than the monoclinic structure, and smaller grain size had higher internal quantum efficiency than larger grain size. External quantum efficiency initially increased with increasing grain size and then decreased. The highest external quantum efficiency was observed at a calcination temperature of 900 °C. These findings provide insight into the factors affecting the crystal structure and photoluminescence behavior in trivalent europium-doped tungstate and molybdate systems.

Perfluoroalkyl Chain Length Effect on Crystal Packing and [LnO8] Coordination Geometry in Lanthanide-Lithium β-Diketonates: Luminescence and Single-Ion Magnet Behavior

Functionalized perfluoroalkyl lithium β-diketonates (LiL) react with lanthanide(III) salts (Ln = Eu, Gd, Tb, Dy) in methanol to give heterobimetallic Ln-Li complexes of general formula [(LnL₃)(LiL)(MeOH)]. The length of fluoroalkyl substituent in ligand was found to affect the crystal packing of complexes. Photoluminescent and magnetic properties of heterobimetallic β-diketonates in the solid state are reported. The effect of the geometry of the [LnO₈] coordination environment of heterometallic β-diketonates on the luminescent properties (quantum yields, phosphorescence lifetimes for Eu, Tb, Dy complexes) and single-ion magnet behavior (U_eff for Dy complexes) is revealed.

Tuning the optical and magnetic properties of lanthanide single-ion magnets using nitro-functionalized trispyrazolylborate ligands

We report the synthesis, crystal structures, photophysical and magnetic properties of 11 novel lanthanide complexes with the asymmetrically functionalized trispyrazolylborate ligand 4-nitrotrispyrazolylborate, 4-NO₂Tp^-: [Ln(4-NO₂Tp)₃] (Ln = La-Dy, except Pm). In-depth photophysical characterization of the ligands via luminescence, reflectance and absorption spectroscopic techniques, decay lifetimes, quantum yields supported by time-dependent density functional theory (TD-DFT) and natural bond order (NBO) analysis reveal that n-NO₂Tp^- ligands are dominated by intra-ligand charge transfer (ILCT) transitions and that second-sphere interactions are critical to the stabilization of the T₁ state of n-NO₂Tp^- ligands and hence their ability to sensitize Ln³⁺ emission. The luminescence properties of the complexes indicate that 4-NO₂Tp^- is a poor sensitizer of Ln³⁺ emission, unlike 3-NO₂Tp^-. Moreover, [Nd(4-NO₂Tp)₃] (crystallized as a hexane solvate) displays single-molecule magnet (SMM) properties, with longer relaxation times and larger barrier than the non-functionalized [NdTp₃], attributed to the addition of the NO₂-group and subsequent rigidification of the molecular structure.