Luminescent thermometry has emerged as a powerful tool for remote temperature sensing, yet the development of sustainable materials that combine robust photophysical performance with environmental compatibility remains a challenge. Herein, we report a bio-derived luminescent thermometric film obtained by incorporating the europium-based complex [Eu (tta)3(PIB)] into a castor-oil-based alkoxysilane polymer (SiCO). The resulting luminescent films are transparent, stable, and preserve the structural integrity and optical characteristics of the trivalent europium (Eu3+) complex, as confirmed by spectroscopic analyses. Efficient ligand-to-metal energy transfer gives rise to well-defined Eu3+ emission, while residual ligand-centered luminescence enables a ratiometric thermometric approach. Temperature-dependent photoluminescence measurements reveal distinct thermal quenching behaviors of the ligand and Eu3+ emissions, allowing reliable temperature readout through an intensity ratio thermometric parameter. The optimized SiCO-0.25Eu film exhibits a maximum relative thermal sensitivity of 1.31% K−1 at 189 K and a minimum temperature uncertainty of 0.43 K at 173 K, maintaining stable performance over a broad low-temperature range (42–282 K) and under repeated thermal cycling. These results demonstrate that castor-oil-derived polymer matrices can serve as efficient and sustainable platforms for luminescent thermometry, offering a promising route toward environmentally friendly luminescent temperature sensors for low-temperature applications.

This work reports the thermometric properties of a heterodinuclear Yb-Er complex, [{Yb(tta)3}(& micro;2-bpm){Er(tta)3}] (1) (tta- = thenoyltrifluoroacetonate and bpm = 2,2'-bipyrimidine), together with the corresponding homodinuclear analogues [{Ln(tta)3}2(& micro;2-bpm)] (Ln = Yb(2), Er(3)). Under 394 nm excitation, complex 1 enables temperature sensing over the 12-310 K range using three luminescence intensity ratio (LIR) readouts based on Yb3+ and Er3+ emissions, while complexes 2 and 3 provide single-ion-based thermometric responses. Among these, the Yb3+ (2F5/2 -> 2F7/2)/Er3+(4I13/2 -> 4I15/2) LIR yields the highest relative thermal sensitivity for 1, with a maximum value (Sm) of 2.5% K-1 at 12 K, and 1.0% K-1 at 310 K. Importantly, 1 represents the first heterodinuclear Yb-Er complex exhibiting thermometric properties and, more remarkably, enabling temperature sensing through three distinct LIR-based readouts. The Yb-only complex 2 exhibits Sm = 3.6% K-1 at 110 K, among the highest reported for Yb3+ molecular thermometers, while Er-based readouts in 1 and 3 provide moderate sensitivities at higher temperatures. Comparative analysis highlights the role of Yb3+ -> Er3+ energy transfer in modulating the thermometric behaviour of the heterodinuclear complex. Theoretical calculations support the presence of metal-metal and ligand-mediated energy-transfer pathways, which contribute to the observed temperature-dependent luminescence response.

Lanthanide (3-diketonate complexes are prominent luminescent materials due to their intense, spectrally pure emissions and their broad utility in sensing, display technologies, and photonics. Their efficiency, however, depends critically on the effectiveness of ligand-to-metal energy transfer and the suppression of non-radiative deactivation. Introducing ancillary N-donor ligands enhances these processes by improving energy-transfer efficiency and reducing vibrational quenching. We report a family of Eu3+ and Sm3+ complexes of general formula LnL3L*, where L is a (3-diketonate (4,4,4trifluoro-1-phenyl-1,3-butanedionate, btfa- , or 2-thenoyltrifluoroacetate, tta- ) and L* a bidentate (1,10-phenanthroline) or tridentate (terpyridine derivatives) N-donor ligand. The complexes were synthesized and characterized by single-crystal and powder X-ray diffraction, Raman, and IR spectroscopies. Photophysical measurements, supported by computational analysis, reveal clear structure-property correlations. All complexes exhibit markedly enhanced emission relative to the parent LnL3 & sdot;2H2O species (Ln = Eu and Sm). The highest luminescence intensities were obtained with 4 '(4-methyl)-2,2 ':6 ',2 ''-terpyridine, followed by 1,10-phenanthroline, 2,2 ':6 ',2 ''-terpyridine, and 2,6-bis(5-(p-methoxyphenyl)-1H-pyrazol-3-yl)pyridine. Overall, these results highlight the critical role of ancillary N-donor ligands in tuning lanthanide photophysics, thereby enabling enhanced emission efficiency and tailored optical properties for advanced luminescent technologies.

Ce3+/Tb3+ codoped RbY3F10 nanophosphors were synthesized by a microwave-assisted solvothermal method and investigated as UV-excited green-emitting materials for latent fingerprint visualization. The study combines structural characterization, steady-state and time-resolved photoluminescence spectroscopy, and proof-of-concept fingerprint development to clarify the relationship between Ce3+ -> Tb3+ sensitization and practical imaging performance. Powder X-ray diffraction confirmed the formation of a single-phase face-centered cubic structure (Fm3m) and successful dopant incorporation, while TEM, EDS, and elemental mapping analyses revealed flower-like aggregates composed of similar to 40 nm primary nanoparticles and a homogeneous distribution of Ce3+ and Tb3+ ions throughout the particles. Photoluminescence measurements revealed efficient sensitization of Tb3+ green emission via Ce3+ -> Tb3+ energy transfer under UV excitation. The composition showing the highest emission intensity within the investigated series was RbY2.1Ce0.3Tb0.6F10. The optimized phosphor exhibits a strong emission peak at 544 nm with an internal quantum yield of 0.47 under 258 nm excitation. Time-resolved photoluminescence measurements revealed a significant shortening of the Ce3+ emission lifetime as Tb3+ concentration increased (0-20 mol %), with a maximum energy transfer efficiency of similar to 90% at the optimized composition. Analysis based on Dexter's multipolar interaction model indicated a dipole-dipole dominated mechanism, supported by a critical transfer distance of similar to 7.5 & Aring;. The combination of high energy-transfer efficiency and stable green emission under UV excitation indicates that Rb-based fluoride hosts are suitable for Ce3+/Tb3+ systems, and their possibility for latent fingerprint visualization was experimentally demonstrated.

Water appears simple, yet its anomalous behavior reveals an unexpected structural complexity. A growing body of evidence indicates that many of water's anomalies arise from fluctuations between low-density (LD) and high-density (HD) local structural motifs, a form of polymorphism that is well established in the supercooled regime and increasingly supported at ambient conditions. Yet, how these structural motifs manifest within hydration layers, where water interacts with nanoparticles, proteins, and charged interfaces, remains far less understood. This interfacial water governs colloidal stability, biomolecular function, and chemical reactivity, but its microscopic organization is difficult to probe directly with conventional bulk techniques. In this Account, we describe how luminescence nanothermometry provides a powerful and versatile approach to accessing density fluctuations in the hydration layer. By monitoring temperature-dependent optical and Brownian observables of luminescent probes, structural reorganizations of the surrounding hydration layer can be inferred with nanoscale sensitivity. Over the past several years, our group has shown that lanthanide-doped upconversion nanoparticles (UCNPs) and fluorescent proteins, such as enhanced green fluorescent protein (EGFP), act as local reporters of hydration-water density fluctuations. A central observation emerging from these studies is the existence of a crossover temperature, Tc, at which hydration-water observables exhibit bilinear temperature dependencies. This Tc correlates with the depletion of LD motifs in the hydration shell and typically falls within the 315-330 K range, close to the minimum of water's isothermal compressibility. Importantly, Tc depends on the nature of the probe and its interaction with the surrounding water. By systematically varying nanoparticle size, pH, surface chemistry, and probe type, we show that previously contradictory trends in Tc can be unified by a single parameter: the effective surface charge density of the probe. When Tc is plotted against this quantity, data from UCNPs with different sizes and surface functionalizations, as well as from fluorescent proteins at different concentrations, collapse onto a master curve. This result demonstrates that interfacial electrostatics govern the stability of LD motifs in the hydration layer, providing a physically intuitive framework that links nanoscale charge distributions to local water structure. We further extend this framework by examining nuclear quantum effects through isotopic substitution. Using EGFP as a model biomolecular probe, we show that replacing H2O with D2O shifts Tc upward by ≈10 K and enhances protein thermal stability, consistent with stronger hydrogen bonding and the displacement of thermodynamic anomalies in heavy water. In contrast, several inorganic and molecular probes fail to resolve a comparable isotopic shift, highlighting that the detectability of LD/HD fluctuations might be probe-dependent. Control experiments in H218O confirm that hydrogen, rather than oxygen, dominates these quantum effects. Together, these results establish luminescent nanoprobes as sensitive reporters of hydration-water density fluctuations and reveal how interfacial charge, confinement, and quantum effects sculpt water structure at the nanoscale. Beyond resolving long-standing questions about water's anomalies, this approach opens new avenues for understanding protein stability, designing functional nanomaterials, and exploiting hydration-water density fluctuations in chemical and biological systems.

The incorporation of luminescent lanthanide complexes into structurally organized solid matrices is of broad interest in materials science, as it enables the development of functional materials with diverse optical properties. In this work the successful preparation of a luminescent stable new hybrid material was carried out. A regular MCM-41 type mesostructured silica was used as support for immobilizing a photostable ternary tetraphenylimidodiphosphinate (tpip)-Eu3+ complex with the co-ligand 1,10-phenantroline (phen). The complex was immobilized using the pore volume impregnation method in dichloromethane. Spectroscopic and photophysical features were analyzed by powder X-ray diffraction, SEM, N2 adsorption/desorption, TGA, UV-Vis and FTIR diffuse reflectance, 29Si solid state NMR spectroscopy and photoluminescence spectroscopy allowing to gather evidence concerning enhanced (photo)stability of the complex upon immobilization.

ABSTRACT Soft photonic materials capable of maintaining optical functionality under large mechanical deformation are highly desirable for wearable photonics, flexible sensors, optical and mechanically adaptive photonic systems. Here, we report highly stretchable luminescent elastomers based on the thermoplastic copolymer PEBAX 2533 incorporating a europium β‐diketonate complex. The transparent films combine intense europium emission with exceptional mechanical flexibility, displaying elongation at break exceeding 1200%, while maintaining high optical transparency in the visible range. The elastomers exhibit intense red luminescence with absolute quantum yields of 0.61. Under mechanical deformation, the 5 D 0 → 7 F 0 transition shows a strain‐dependent spectral shift and intensity modulation, enabling optical strain readout with sensitivities of –1.6 ± 0.2 cm −1 ·ε −1 and −0.44 ± 0.04 ε −1 , respectively. The luminescence spectra also display a thermal dependence, characterized by a blue shift and intensity decrease of the Eu 3+ emission with a temperature sensitivity of 0.08 ± 0.01 cm −1 ·°C −1 over the investigated temperature range. The coexistence of large deformability, high transparency, efficient Eu 3+ emission, and two independently calibrated optical responses establishes Eu‐doped elastomers as a versatile soft photonic platform for multimodal optical transduction, highlighting their potential for flexible sensing technologies in which mechanical and thermal perturbations are optically encoded within the same material platform.

Tuning the excitation source (UV or NIR) in the Nd 3+ dimer allows modulation of its thermal response, providing high relative sensitivities at low and physiological temperature ranges, and setting a new benchmark for Nd-based molecular thermometry.

Anomalies in liquid water are increasingly rationalized by a two-state model involving fluctuations between lowdensity (LD) and high-density (HD) motifs. Luminescent nanoprobes, including upconversion nanoparticles (UCNPs), quantum dots (QDs), and fluorescent proteins, offer unique optical access to LD/HD fluctuations in the hydration layer surrounding nanoprobes. We previously established a master curve linking the crossover temperature Tc (marking LD motif depletion) to effective surface charge density (6f) for aqueous dispersions of NaGdF4:Yb/Er UCNPs. Here we test its generality across diverse optical probes and solvents, including CdTe QDs (1.5-3 nm), enhanced green fluorescent protein (EGFP) in H2O and D2O, 100 nm silica-coated UCNPs in water, ) and 15 nm UCNPs in H2 18O. While EGFP and silica-coated UCNPs in H2O follow the predicted sigmoidal Tc ( 6f scaling, CdTe QDs and isotopically modified systems exhibit clear deviations. Small CdTe QDs exceed the model high-6f validity range due to nonlinear zeta potential-charge relations, while isotopic effects perturb hydrogenbond dynamics. Despite deviations, Tc increases monotonically with 6f, establishing interfacial electrostatics as the primary control parameter. These results delineate the operating limits of the master curve and provide design guidelines for charge-tunable luminescent probes in aqueous thermometry and nanoscale water sensing.

Lanthanide-based carriers have emerged as powerful platforms for next-generation biomedical imaging, combining unique optical and magnetic features to address key limitations of conventional agents. Owing to their 4f electron configuration, lanthanide ions provide sharp emission lines, long lifetimes, high photostability, and strong paramagnetism, enabling high-resolution, multiplexed, and deep-tissue imaging with minimal photodamage. This review surveys recent advances across optical, X-ray, and magnetic resonance modalities, focusing on how material design influences performance. We examine representative carriers, such as lanthanide-doped nanoparticles, organic complexes, and lanthanide-binding proteins, and their roles in near-infrared (NIR) imaging (long-term single-particle tracking, molecular sensing, and NIR-II modalities), X-ray imaging (contrast media, scintillators, and persistent emitters for low-dose diagnostics), and magnetic resonance imaging (chemical and biosynthetic agents with enhanced relaxivity, specificity, and safety, including targeted protein constructs). We highlight molecular engineering and surface modification strategies that boost signal and biocompatibility, and discuss emerging directions such as artificial intelligence-enabled data analysis and the integration of multimodal probes to deliver integrated anatomical and functional information. While most advances are still at the proof-of-concept stage, lanthanide carriers show great potential for bridging materials science, biophysics, and clinical needs, and are reshaping biomedical imaging toward more precise, responsive, and personalized diagnostics.

The development of ideal marine-engineering materials is confronted with problems associated with corrosion and sailing resistance. In the current study, we prepared a Fe3O4 nanoparticle-based nano-oil and employed it to form a slippery liquid-infused porous surface (SLIPS) on 2024 aluminum alloy. As synthesized, the SLIPS reduced drag in a sailing experiment by 30% and biofouling by 99.7%, and exhibited a more than 2 orders of magnitude greater anticorrosion performance. Owing to its integrated functions for drag reduction, anti-biofouling, and anticorrosion, the newly uncovered Fe3O4 nanoparticle-based nano-oil has great potential for applications in marine material engineering. [GRAPHICS]

This review shows polymer-modified lanthanide-doped UCNPs enhance stability, biocompatibility and multifunctionality, enabling advances in bioimaging, phototherapy, drug delivery and biosensing, and outlines routes toward clinical translation.

Understanding the dynamics of photophysical processes in Ln3+ complexes remains challenging due to the intricate nature involving the metallic center, where sensitization (antenna effect) plays a pivotal role. Current studies have often overlooked the vibronic coupling within the antenna effect, leading to incomplete insights into excited-state dynamics. To address these shortcomings, we introduce a novel theoretical and computational approach that leverages the impact of the vibrational modes of the S1 and T1 states in this effect through the correlation function formalism, offering a comprehensive view of intersystem crossing (ISC). Our approach achieves a desirable alignment between empirical and theoretical rates, outperforming previously employed semiclassical methods. A groundbreaking finding is that vibronic coupling with vibrations in the 700-1600 cm-1 energy range is crucial for higher ISC, and local vibrational mode analysis identified that this process is driven by delocalized vibrations across the molecule. These results shed light on the key molecular fragments responsible for vibronic coupling, opening an avenue for harnessing faster ISC by tailoring the ligand scaffold. Overall, it also demonstrates how ISC dynamics can serve as a bridge between theory and experiment, furnishing detailed mechanistic insights and a roadmap for the development of brighter compounds.

Examples of molecular complexes acting as thermometers operating at room temperature in near infrared region are scarce, therefore this work showcases the anti-thermal quenching effect on neodymium(III) molecular thermometers working in biological windows within the physiological temperature range. A mononuclear complex, [Nd(L)(NO3)3] (1Nd), where L is a macrocyclic ligand, was synthesized and used as a precursor to develop two novel species: a dinuclear, [(Nd(L)(NO3))2(µ-BDC)](NO3)2·H2O (2Nd), linked by 1,4-benzenedicarboxylate (BDC), and a hexameric, [(Nd(L))(µ-BTC)(H2O)]6·35H2O (6Nd), linked with 1,3,5-benzenetricarboxylate (BTC). Thermometric properties were studied in the physiological temperature range (292-332 K), utilizing 804 nm laser excitation (first biological window) and monitoring emissions in the second biological window (908, 1065, and 1340 nm) associated with the 4F3/2 → 4I9/2, 4I11/2, 4I13/2 transitions, respectively. Among the complexes, the hexamer 6Nd exhibited exceptional performance, with Sr of 2.4%K-1 at 293 K, when luminescence intensity ratio (LIR) of two Stark components of the 4F3/2 → 4I11/2 emission was used, positioning it as a high-performance NdIII-based thermometer. All complexes displayed anti-thermal quenching behavior, surpassing the current molecular-based thermometers in the near-infrared region. Theoretical calculations using complete active space self consistent field (CASSCF) and Boltzmann population models between Kramers doublets of the 4F3/2 level were performed to rationalize the anti-thermal behavior.

The anomalous properties of water are increasingly understood in terms of its structural fluctuations between high-density (HD) and low-density (LD) domains. However, the temperature at which these fluctuations vanish upon heating (the crossover temperature, Tc) and the fraction of LD domains under ambient conditions remain debated, particularly near interfaces. Here, we demonstrate that the surface charge density of colloidal upconverting nanoparticles (UCNPs) plays a key role in controlling Tc within the hydration layer, i.e., the water molecules forming the interfacial layer directly interacting with the nanoparticle surface. By combining the reanalysis of existing data with new experiments on compositionally similar UCNPs bearing different surface functionalizations, we demonstrate that Tc increases systematically with surface charge density. This trend holds regardless of particle size, surface chemistry, or pH. These results clarify previous conflicting findings and establish surface charge as a major factor governing the transition between LD and HD domains in hydration water. Beyond nanotechnology, these insights provide a framework for understanding how hydration water modulates biological processes, including protein stability and unfolding, where hydration shell dynamics play a determining role.

A bifunctional molecular material operates as both a magnet (40 K blocking temperature) and luminescent thermometer within the same temperature range.

The study explores the effectiveness of various machine learning algorithms for luminescence thermometry. We demonstrate that the Convolutional Neural Network outperforms other machine learning algorithms and the ratiometric classical approach.