Search Results (1,781)

A new class of Ln(III) Schiff base (SB) complexes has been synthesized with the general formula [LnL(hfac)₃], where Ln = Tb (TbL), Eu (EuL), Sm (SmL) or Gd (GdL). The molecular structure of the complex was determined using the X-ray diffraction method. The IR spectra show that the C=O stretching is shifted from 1695 cm⁻¹ in pure PMMA to 1719–1724 cm⁻¹ in LnL-PMMA hybrid materials. This means that LnL materials are successfully embedded into the PMMA backbone in the polymeric films. However, the Ln(III) SB complexes exhibit emission spectra that cover the visible region. The TbL complex displays an intense green emission combined with a large emission lifetime of 0.505 ms. However, the incorporation of Ln-SB complexes into PMMA (polymethylmethacrylate) polymeric films was investigated. The thermal stabilities of the LnL-PMMA hybrid materials increased from 140 to 250 °C when compared with the LnL-SB complexes. Furthermore, their luminescence intensity and lifetimes were also enhanced due to their induced structural rigidity. The molecular interactions of the LnL complexes with the PMMA matrix were monitored by investigating the luminescence properties of EuL-PMMA. Detailed photoluminescence studies showed insights into the non-radiative rates and improved quantum yields (Q_Eu = 23%) from Eu(III). Furthermore, the higher values of Judd–Ofelt parameters Ω₂ and Ω₄ indicate strong hydrogen bonding interactions between L and PMMA. Nevertheless, these significant optical properties enable LnL-PMMA polymeric materials as colored phosphors for the design of opto-electronic devices. Full article

Glass-ceramics are inorganic, non-metallic materials obtained by controlled crystallization of glasses through different processing routes; they contain at least one functional crystalline phase together with a residual glass, and the crystallized fraction may range from trace levels to nearly complete crystallization. Transparent glass-ceramics (TGCs) constitute the optically transparent subset of this class and combine a controlled crystalline microstructure with a residual amorphous matrix. Their transparency distinguishes them from conventional opaque glass-ceramics and is achieved by minimizing light scattering through careful control of crystallite size, volume fraction, spatial distribution, and refractive-index mismatch between the crystalline and glassy phases. Unlike conventional sintered ceramics, TGCs retain many of the processing advantages of glass while incorporating crystalline phases that can enhance mechanical, thermal, optical, or functional properties. Depending on their composition and microstructure, TGCs may exhibit improved hardness, fracture toughness, thermal stability, chemical durability, luminescence, nonlinear optical response, or ion-exchange strengthening capability. These features make TGCs attractive for applications requiring both optical clarity and advanced performance, including protective cover glass, transparent armour, precision optical substrates, laser and photonic components, optical sensors, and multifunctional host materials for rare-earth ions and nanoparticles. Full article

Lanthanide-doped Ca₂Nb₂O₇ offers versatile and tunable luminescence properties. Previous studies have shown that Pr³⁺-doped and Pr³⁺/Er³⁺ co-doped Ca₂Nb₂O₇ ceramics exhibit non-destructive mechanoluminescence, up- and down-conversion luminescence, and thermoluminescence, with potential for optical temperature sensing. However, to date, niobate glass–ceramics (GCs) remain largely unexplored, although they would offer excellent temperature resistance, high chemical durability, controllable crystallization, and the possibility to combine functional properties. This study investigates Pr³⁺ single doping and Pr³⁺/Er³⁺ co-doping in glass–ceramics prepared from niobium-containing calcium aluminosilicate glasses with the composition 55CaO-(35-x)Al₂O₃-10SiO₂-xNb₂O₅ (mol%, where x = 0, 10). The aim is to obtain glass–ceramics containing Ca₂Nb₂O₇ crystals with a layered perovskite structure and to evaluate their suitability as hosts for rare-earth ions. The luminescence properties of both parent glasses and GCs were investigated, and it is shown that the glasses show intrinsic luminescence which, when doped, enables sensitization of rare-earth elements via charge transfer. Furthermore, several interesting photoluminescence mechanisms were observed in the doped GCs, including (i) Er³⁺ up-conversion from the NIR to the visible, (ii) variations in the relative intensities of Er³⁺ hypersensitive transitions, reflecting changes in site symmetry, and (iii) a charge transfer process to the activator ions under UV excitation. These phenomena extend the accessible excitation range for rare-earth emission. Overall, the developed Ca₂Nb₂O₇ GCs demonstrate efficient dopant integration, confirming their suitability as lanthanide hosts for advanced photonic, sensing and energy conversion applications. Full article

This mini-review is intended to show how multimodal imaging could be developed from prototypes and proofs of concept by controlling the nanoscale for improved resolution of life science imaging for broad applications such as bioassays, early diagnoses and further applications. It intends to afford the presentation of multimodal approaches for imaging and bioimaging uses with potential applications to biological media. The application of multimodal nanoemitters provides enhanced bioimaging through the generation of various targeted and well-defined signals. Radionuclides and luminescent emitters were considered in the discussion for improved and enhanced signaling. In this manner, we intended to show the increase in the power of information by collecting varied optical signal–matter interactions. This could be important for Positron Emission Tomography and Computed Tomography (PET-CT), Fluorescence Tomography (FT), and other new modes of imaging contemplating the incorporation of nanotechnology. In the context of the design of new multimodal energy modes, key examples were shown from the literature, where the interactions of different energy modes could lead to enhanced and improved signaling. Electromagnetic fields and nanoplasmonics are involved in these different energy modes involving varied quantum particle interactions with modified properties. In this regard, multimodal imaging has experienced developments in nanoemitters and nanobiolabeling to track biomolecular events and targeted cells. A large quantity of research output actually focuses on nano- and quantum emissions. However, there are not as many studies dealing with enhanced emissions or laser emissions coupled with radionuclide emitters. A non-classical form of light emission, considering varied luminescent phenomena as well as further quantum signaling, showed interesting and high-impact perspectives when combined with nuclear emissions. This is the case for current trends focusing on innovative single-cell analysis. For example, the characterization and diagnosis of cells where the targeting of antibody–antigen interactions is required, providing light and energy from different sources to produce different details and imaging resolutions, has been noted. These are potential approaches that could be developed through various strategies targeting life science applications. In this regard, this article puts forward a discussion focused on nanotechnology contemplating radio-pharmacy and enhanced nanoemitters. Full article

Fungal infections remain a major threat to human health, with non-albicans Candida (NAC) species causing more than half of all clinical cases and many strains gaining resistance to current treatments rapidly. Previously, N-arachidonoyl ethanolamine (anandamide, AEA) has been studied and shown to possess antibacterial and antifungal properties against various bacteria and Candida albicans. Given the previous findings, we aim here to expand the current preliminary research on AEA to investigate its antifungal activities against clinically relevant NAC species in vitro: Candida glabrata, Candida parapsilosis, and Candidaozyma auris. The minimum inhibitory concentration (MIC) and growth curve analysis determined planktonic inhibition. MTT metabolic assay and ATP production via BacTiter-Glo luminescence assay evaluated biofilm formation. Membrane fluidity, polarization and efflux pump activity were examined using fluorescence probes Laurdan, DiS-C3(3), and Rhodamine 6G, respectively. Reactive oxygen species (ROS) were assessed using DCFH-DA. Biofilm architecture and cell viability were analyzed by spinning disk confocal microscopy (SDCM). AEA reduced MIC values and slowed planktonic growth, while MTT and ATP assays demonstrated a pronounced dose-dependent reduction in biofilm metabolic activity. Membrane-targeted effects revealed increased fluidity and permeability at 125 µg/mL. Notably, AEA rapidly impaired efflux pump activity and induced intracellular ROS production. This effect was accompanied by reduced cell viability, increased proportions of PI-positive cells, and enhanced intracellular dye retention, as confirmed by SDCM. Together, these findings demonstrate that AEA exerts antifungal activity by disrupting membrane integrity and associated cellular functions and provide the first comparative characterization of species-specific membrane and oxidative stress responses to AEA across three major clinically relevant multidrug-resistant NAC species. Full article

Metal–Organic Frameworks (MOFs) have undergone remarkable development in recent decades, transforming them into one of the most dynamic classes of emerging composite materials. These crystalline, porous coordination networks, built from metal ions or metal clusters interconnected by organic linkers, form architectures with tunable porosity, large specific surface area, and chemical functionality. Due to their remarkable stability and customizable functionalities, MOFs have attracted significant attention in recent years as promising materials for different applications. In 2025, Susumu Kitagawa, Omar Yaghi, and Richard Robson were awarded the Nobel Prize in Chemistry for pioneering the development of MOF crystalline materials with spacious internal cavities that can store, filter or catalyze molecules. This review systematically consolidates the recent literature (since 2020) on MOF-based systems, covering state-of-the-art performance, synthesis advantages and limitations, and the influence of reaction parameters on morphology, structure, and luminescent properties. The rapid yearly increase in MOF-related publications, continuing strongly into 2026, reflects the growing global interest and highlights the rising importance of their design and applications. This trend motivates the central focus of this paper, which, in a single work, emphasizes the integrated use of MOFs in luminescent sensing, biosensing, the removal of heavy metals, microplastics, and organic dyes in water treatment, and hydrogen storage. Finally, the challenges, conclusions and future perspectives of MOF-based materials will be highlighted with the aim of providing guidelines for their further development and additional applications. Full article

A series of novel heterometallic rare-earth chloroterephthalate metal–organic frameworks with the general formula (Tb_xGd_1−x)₂(Cl-1,4-bdc)₃·5H₂O (x = 0–1) were synthesized via direct precipitation from aqueous solutions. The structural and photophysical properties of these compounds were studied in detail. All compounds exhibit bright luminescence upon UV excitation into the ligand absorption band due to an efficient antenna effect. The photoluminescence quantum yield shows a non-monotonic dependence on the concentration of the terbium ion with a maximum value of 71% achieved for the compound containing equal molar fractions of the lanthanide ions. The (Tb_0.5Gd_0.5)₂(Cl-1,4-bdc)₃·5H₂O sample was evaluatedfor its utility in both qualitative and quantitative analysis of selected metal ions and in latent fingerprint development. It was shown to enable the detection of Cr(III), Fe(III), and Cu(II) ions through luminescence quenching, with the emission intensity being concentration-dependent. This behaviour highlights the compound’s potential as a basis for analytical protocols and materials aimed at the quantitative determination of these metal ions. Full article

In this work, a comprehensive analysis of the relationship between photoluminescent, thermo-oxidative, and photocatalytic (upon simulated sunlight exposure) properties of ZnO powders is performed. The correlation between the X-ray diffraction and microscopic data is studied. ZnO powders of various sizes and morphologies were used: pseudo-spherical nanoparticles (30–50 nm), submicron faceted crystallites (100–500 nm), and plate- and rod-like microstructures (up to 20 μm). The mean specific surface area values were 32 m²/g, 3.8 m²/g, and 2.6 m²/g for pseudo-spherical nanoparticles, submicron faceted crystallites, and plate- and rod-like microstructures, respectively. According to the XRD data, microstresses and carbon-based impurities were present in ZnO nanoparticles, which is characteristic of nanomaterials synthesized at low temperatures. According to the photoluminescence spectroscopy data, the emission in ZnO was reduced due to high defectiveness, and characteristic emission bands indicated the presence of organic impurities. Upon long signal registration times, an intensive luminescence band with an effective maximum at 579 nm occurred, which indicated the presence of long-term components exhibiting decay times τ ~300 μs. According to the XRD data, the crystal structure parameters of ZnO submicro- and microparticles were close, with no impurities present. In their photoluminescence spectra, pronounced UV and defect-related bands were present with intensity ratios of 11.6 and 6.88, respectively. The decrease in the UV and defect-related luminescence band intensity ratios indicates deviation from the stoichiometry toward an increased Zn over oxygen content. At long signal registration times, in submicron ZnO particles, a luminescence band with maxima at 425 and 490 nm is present, which decays rapidly. An emission band in the 530 nm region is also present, which decays for ≤80 μs, and a weak long-wavelength emission decaying for ~100 μs. At long delay and strobe times (up to milliseconds), only an emission in the 460 nm region is observed, which we connect to the triplet–singlet transition of a defect center (F*, F⁺*). At lower intensities, an emission connected to the surface contamination by organic impurities is observed. In photoluminescence spectra of ZnO microparticles, no long-wavelength emission components are observed. However, upon immersing into methylene blue solution, a modification of the surface and UV region of the spectra is observed with signs of charge carrier recombination rate acceleration. It is shown that the catalytic action of ZnO powders in polyethylene thermo-oxidation processes is determined by a combination of factors. In addition to dispersity and concentration, which are the key parameters, the morphology of ZnO particles, the presence of impurities, the surface state, and the distribution of active sites have a significant influence on catalysis. It has been experimentally demonstrated that these secondary factors can markedly affect the rate of radical formation in polyethylene films and alter their resistance to oxidation. ZnO nanoparticles exhibited low catalytic activity in both photocatalysis (rate constant 0.146 min⁻¹) and thermocatalysis due to the high defect density of the crystallites and the presence of carbon-containing impurities. Submicron ZnO particles, owing to a high carrier generation rate and suppressed recombination (via trapping), demonstrated the highest photoactivity (rate constant 0.729 min⁻¹). Submicron ZnO particles exhibit a catalytic effect on the thermo-oxidation of polyethylene (PE films); however, at concentrations above 8 wt.% a transition to an inhibiting effect is observed. ZnO microparticles catalyzed the oxidation of PE films over a broader concentration range (1–12 wt.%), with oxidation inhibition observed only at 18 wt.%. At the same time, they demonstrated moderate photocatalytic activity (rate constant 0.256 min⁻¹). These characteristics of the samples correlate with data obtained by microscopy, photoluminescence spectroscopy, and X-ray diffraction analysis. Full article

SrAl₂O₄: Eu²⁺, Dy³⁺ polymeric composites are the reference photoluminescent materials in passive signaling due to their high emission intensity and long luminescent persistence. But their real long-term outdoor durability is still poorly understood. This study analyzes a strontium aluminate polymer composite exposed to real weathering for 15 years to evaluate its degradation threshold, exceeding the frameworks of accelerated tests. Using FTIR, Raman, FE-SEM, colorimetry and phosphorescence decay, the weathered material was compared with its reference material. Results show that the luminescent composite retains its structural properties, its optical functionality improving its mechanical properties (increasing the flexural strength between 23 and 64% and microhardness between 136 and 164%), while suffering only a small yellowing, suggesting a longer service life than expected. Finally, it was established that the loss in the optical performance is not due to irreversible degradation of the polymer or pigment but is caused by the accumulation of surface dust and the formation of an opaque outer layer. The application of mechanical surface polishing removes this polluting layer, restoring optical transmittance and effectively recovering almost the original luminosity of the photoluminescent system. Full article

Natural blue calcite is relatively rare, and its coloration and luminescence mechanisms have not been systematically established. In this study, four natural blue calcite samples from China were comprehensively characterized using mineralogical testing, X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), photoluminescence (PL), and electron paramagnetic resonance (EPR). XRD confirms single-phase trigonal calcite (space group R-3c). EPMA detects minor Mg, Fe, Cu, and Sr, with smaller-radius Mg²⁺, Fe²⁺, and Cu²⁺ being the main contributors to the contraction through isomorphous substitution for Ca²⁺. UV-Vis spectra show characteristic absorptions at 270 nm and 340 nm related to lattice defects with a broad emission band centered at 480 nm in the PL spectra. EPR detects a CO₂⁻ radical center (g = 2.003), and the same signal is also observed in the colorless sample. The colorless sample also contains the same CO₂⁻ radicals, indicating that these radicals alone do not account for the blue coloration. A broad 480 nm blue-violet fluorescence band is observed in the four blue samples under 405 nm excitation. These findings provide a spectroscopic and crystallographic basis for distinguishing natural blue calcite from analogous materials and for understanding the origin of its color and luminescence. Full article

All inorganic CsPbBr₃ perovskite nanocrystals (NCs) exhibit outstanding luminescence for optoelectronics, yet poor environmental stability severely restricts their practical deployment. As a stable derivative phase, Cs₄PbBr₆ can effectively improve structural stability. Nevertheless, the rational fabrication of high-quality Cs₄PbBr₆/CsPbBr₃ hybrid NCs remains challenging owing to the lack of straightforward and scalable synthetic strategies. To overcome these hurdles, we synthesize well-defined Cs₄PbBr₆/CsPbBr₃ hybrid NCs via a temperature-controllable continuous-flow microfluidic route. This platform precisely modulates phase composition via systematic temperature tuning across a range of 110–170 °C, producing distinct compositions from Cs₄PbBr₆-dominant to high-purity CsPbBr₃. A direct correlation was elucidated between temperature-induced phase transformation and optical properties. The NCs synthesized at 130 °C exhibited a high photoluminescence quantum yield of 96.24% and bright 521 nm green emission. These NCs were successfully integrated into white light-emitting diodes incorporating a 478 nm blue excitation chip and K₂SiF₆:Mn⁴⁺ red phosphor, which demonstrated excellent color performance with a luminous efficiency of 86.3 lm W⁻¹ and Commission Internationale de l’Éclairage coordinates of (0.2991, 0.3784). This work highlights the potential of continuous-flow microfluidics for precise phase modulation and scalable production of high-quality perovskite NCs, offering a viable route for advanced optoelectronic applications. Full article

This paper investigates the spectral properties of colloidally ordered systems formed from 100 nm nanodiamonds (NDs) synthesized using the high-pressure high-temperature (HPHT) method. Despite the polydispersity and irregular shape of the particles, aqueous ND suspensions can colloidally order via repeated centrifugation-induced sedimentation. To the best of our knowledge, this is the first spectroscopic study of such ordered ND systems. In our study, we obtained colloidally ordered ND structures, evidenced by the formation of rainbow-colored layers in the centrifuge tubes. Fragments extracted from these layers were subjected to microscopic and spectroscopic characterization. Spectroscopic measurements with 488 nm wavelength laser reveal modulated emission in a narrower spectral range, lying within the characteristic broad emission band of NDs and indicating the formation of ordered structures with a characteristic micrometer scale. In view of the intrinsic luminescence of NDs, we propose that these structures are best regarded as analogous to colloidal photonic crystals with intrinsic luminescence. This concept can significantly extend the functionality of ND-based materials and offers new opportunities for fundamental optical studies and practical photonic applications. Full article

Three new isomeric pyridone fluorenone hydrazone-based boron complexes, 3-BrN to 5-BrN, with bromination at the 3-, 4-, or 5-position of the pyridone ring and their corresponding σ-platinum complexes trans-Pt(PEt₃)₂(n-N)X (n = 3, 4, or 5; X = Cl, Br, I) resulting from oxidative addition of the aryl-Br bond of n-BrN to Pt(PEt₃)₂ and, for X = Cl, I, subsequent substitution of the halogenide ligand, were synthesized and characterized by NMR, UV–Vis absorption, and photoluminescence spectroscopy. The molecular structures of dyes 3-BrN to 5-BrN and of seven complexes, including the cis-isomer of the bromo complex resulting from 3-BrN, were established by single X-ray diffraction. The nearly orthogonal orientation of the Pt coordination plane with respect to the plane of the dye ligand limits intermolecular π-stacking interactions in the crystalline state while giving rise to extensive C-H···halogen and C-H···π interactions, resulting in intricate packing patterns. Electronic absorption spectra of dyes 3-BrN to 5-BrN show a prominent HOMO-LUMO absorption band at ca. 520 nm, which is red-shifted and intensifies on platination. All compounds are dual fluorescence and phosphorescence emitters in the range of 520 to 670 nm, or at ca. 1000 nm, both at room temperature and at 77 K. The population of an excited triplet state and their photostability even towards continuous light irradiation renders these compounds efficient sensitizers for singlet oxygen generation and catalysts for the photo-oxidation of triphenylphosphine. Full article

The accurate discrimination of structurally analogous neurotransmitters remains a formidable challenge due to their high structural similarity and overlapping chemical properties. To address the limitations of low specificity in single-probe sensors and the fabrication complexity of multi-component arrays, we developed a simplified fluorescence sensing array based on a single pyrene-functionalized MOF, In-TBAPy. This strategy leverages the distinctive monomer-to-excimer luminescence transition of In-TBAPy, triggered by the tunable π-π stacking of pyrene units within the crystalline framework. The results demonstrate that the array, integrated with Linear Discriminant Analysis (LDA) across four optimized emission channels, achieves a classification accuracy of 93.75% in identifying four highly similar neurotransmitters: serotonin (5-HT), dopamine (DA), adrenaline (A), and norepinephrine (NA). Notably, the sensing platform exhibits exceptional robustness in simulated physiological environments and complex multi-analyte mixtures, enabling reliable quantitative analysis: 0–100 μM for 5-HT and adrenaline (A), 0–40 μM for dopamine (DA), and 0–80 μM for norepinephrine. Mechanistic studies suggest that the differential quenching of monomer and excimer peaks stems from the synergistic effect of competitive absorption and host–guest interactions. This work effectively overcomes the cross-interference issues of traditional sensors and validates a high-efficiency solution for high-throughput neurotransmitter analysis using a single-material-based array strategy, significantly reducing operational costs and preparation time. Full article

A novel Dy³⁺-doped self-activated Sr₂NaMg₂V₃O₁₂ (SNMVO) phosphor was synthesized via a high-temperature solid-state reaction method. Its microstructure, surface morphology, valence state, and luminescence properties were investigated. The results showed that the prepared phosphor exhibited bright green emission at 521 nm and yellow emission at 575 nm under 345 nm excitation. The luminescence intensity showed a strong concentration dependence, with an optimal Dy³⁺ ion doping concentration of 0.05 mol, and the concentration quenching (CQ) mechanism was dipole–dipole (d-d) interaction. Energy transfer between vanadate and Dy³⁺ was observed, with a maximum transfer efficiency of 63.5%. The thermal activation energy (0.1859 eV) indicated good thermal stability. Furthermore, this phosphor can be used as a yellow phosphor for white light-emitting diodes (wLEDs) and for anti-counterfeiting patterns. Full article