Lanthanide-Grafted Bipyridine Periodic Mesoporous Organosilicas (BPy-PMOs) for Physiological Range and Wide Temperature Range Luminescence Thermometry

Dual-signalled magneto-optical barcodes with lanthanide-based molecular cluster-aggregates

A proof-of-concept for magneto-optical barcodes is demonstrated for the first time. The dual-signalled spectrum observed via magnetic circular dichroism spectroscopy can be used to develop anti-counterfeiting materials with extra layers of security when compared with the widely studied luminescent barcodes.

Hybrid multifunctionalized mesostructured stellate silica nanoparticles loaded with β-diketonate Tb3+/Eu3+ complexes as efficient ratiometric emissive thermometers working in water

Despite the great effort made in recent years on lanthanide-based ratiometric luminescent nanothermometers able to provide temperature measurements in water, their design remains challenging. We report on the synthesis and properties of efficient ratiometric nanothermometers that are based on mesoporous stellate nanoparticles (MSN) of ca. 90 nm functionalized with an acetylacetonate (acac) derivative inside the pores and loaded with β-diketonate-Tb3+/Eu3+ complexes able to work in water, in PBS or in cells. Encapsulating a [(Tb/Eu)9(acac)16(μ3-OH)8(μ4-O)(μ4-OH)] complex (Tb/Eu ratio = 19/1 and 9/1) led to hybrid multifunctionalized nanoparticles exhibiting a Tb3+ and Eu3+ characteristic temperature-dependent luminescence with a high rate Tb3+-to-Eu3+ energy transfer. According to theoretical calculations, the modifications of photoluminescence properties and the increase in the pairwise Tb3+-to-Eu3+ energy transfer rate by about 10 times can be rationalized as a change of the coordination number of the Ln3+ sites of the complex from 7 to 8 accompanied by a symmetry evolution from Cs to C4v and a slight shortening of intramolecular Ln3+-Ln3+ distances upon the effect of encapsulation. These nanothermometers operate in the 20-70 °C range with excellent photothermal stability, cyclability and repeatability (>95%), displaying a maximum relative thermal sensitivity of 1.4% °C-1 (at 42.7 °C) in water. Furthermore, they can operate in cells with a thermal sensitivity of 8.6% °C-1 (at 40 °C), keeping in mind that adjusting the calibration for each system is necessary to ensure accurate measurements.

Lanthanide-grafted hollow bipyridine-based periodic mesoporous organosilicas as chemical sensors

We have synthesized a co-condensed hollow ethane-bipyridine periodic mesoporous organosilica (HEt-bpy-PMO) as a host material to anchor lanthanides for the purpose of developing a multifunctional chemical sensor. The host material was grafted with lanthanide chloride salts or complexes. The luminescence properties of the developed series of hybrid materials were studied in detail in the solid-state and after dispersing in water. The Eu3+ or Tb3+ singly incorporated materials were investigated for their use as ion sensors, showing ions selectivity towards Cu2+, Co2+ and Fe3+. Additionally, the Eu3+ or Tb3+ incorporated materials showed obvious luminescence quenching behavior towards acetone compared to other organic solvents, indicating excellent acetone sensing selectivity.

Ratiometric Luminescent Thermometer Based on the Lanthanide Metal-Organic Frameworks by Thermal Curing

The high-performance optical thermometer probes are of great significance in diverse areas; lanthanide metal-organic frameworks (Ln-MOFs) are a promising candidate for luminescence temperature sensing owing to their unique luminescence properties. However, Ln-MOFs have poor maneuverability and stability in complex environments due to the crystallization properties, which then hinder their application scope. In this work, the Tb-MOFs@TGIC composite was successfully prepared using simple covalent crosslinking through uncoordinated -NH₂ or COOH on Tb-MOFs reacting with the epoxy groups on TGIC {Tb-MOFs = [Tb₂(atpt)₃(phen)₂(H₂O)]_n; H₂atpt = 2-aminoterephthalic acid; phen = 1,10-phenanthroline monohydrate}. After curing, the fluorescence properties, quantum yield, lifetime, and thermal stability of Tb-MOFs@TGIC were remarkably enhanced. Meanwhile, the obtained Tb-MOFs@TGIC composites exhibit excellent temperature sensing properties in the low-temperature (S_r = 6.17% K^-1 at 237 K), physiological temperature (S_r = 4.86% K^-1 at 323 K), or high-temperature range (S_r = 3.88% K^-1 at 393 K) with high sensitivity. In the temperature sensing process, the sensing mode of single emission changed into double emission for ratiometric thermometry owing to the back energy transfer (BenT) from Tb-MOFs to TGIC linkers, and the BenT process enhanced with the increase of temperature, which further improved the accuracy and sensitivity of temperature sensing. Most notably, the temperature-sensing Tb-MOFs@TGIC can be easily coated on the surface of polyimide (PI), glass plate, silicon pellet (SI), and poly(tetrafluoroethylene) plate (PTFE) substrates by a simple spraying method, which also exhibited an excellent sensing property, making it applicable for a wider T range measurement. This is the first example of a postsynthetic Ln-MOF hybrid thermometer operative over a wide temperature range including the physiological and high temperature based on back energy transfer.

1,10-Phenanthroline-based periodic mesoporous organosilica: from its synthesis to its application in the cobalt-catalyzed alkyne hydrosilylation

1,10-Phenanthroline (Phen) is a typical ligand for metal complexation and various metal/Phen complexes have been applied as a catalyst in several organic transformations. This study reports the synthesis of a Phen-based periodic mesoporous organosilica (Phen-PMO) with the Phen moieties being directly incorporated into the organosilica framework. The Phen-PMO precursor, 3,8-bis[(triisopropoxysilyl)methyl]-1,10-phenanthroline (1a), was prepared via the Kumada-Tamao-Corriu cross-coupling of 3,8-dibromo-1,10-phenanthroline and [(triisopropoxysilyl)methyl]magnesium chloride. The co-condensation of 1a and 1,2-bis(triethoxysilyl)ethane in the presence of P123 as the template surfactant afforded Phen-PMO 3 with an ordered 2-D hexagonal mesoporous structure as confirmed by nitrogen adsorption/desorption measurements, X-ray diffraction, and transition electron microscopy. Co(OAc)₂ was immobilized on Phen-PMO 3, and the obtained complex showed good catalytic activity for the hydrosilylation reaction of phenylacetylene with phenylsilane.

Magneto-Induced Hyperthermia and Temperature Detection in Single Iron Oxide Core-Silica/Tb3+/Eu3+(Acac) Shell Nano-Objects

Multifunctional nano-objects containing a magnetic heater and a temperature emissive sensor in the same nanoparticle have recently emerged as promising tools towards personalized nanomedicine permitting hyperthermia-assisted treatment under local temperature control. However, a fine control of nano-systems' morphology permitting the synthesis of a single magnetic core with controlled position of the sensor presents a main challenge. We report here the design of new iron oxide core-silica shell nano-objects containing luminescent Tb³⁺/Eu³⁺-(acetylacetonate) moieties covalently anchored to the silica surface, which act as a promising heater/thermometer system. They present a single magnetic core and a controlled thickness of the silica shell, permitting a uniform spatial distribution of the emissive nanothermometer relative to the heat source. These nanoparticles exhibit the Tb³⁺ and Eu³⁺ characteristic emissions and suitable magnetic properties that make them efficient as a nanoheater with a Ln³⁺-based emissive self-referencing temperature sensor covalently coupled to it. Heating capacity under an alternating current magnetic field was demonstrated by thermal imaging. This system offers a new strategy permitting a rapid heating of a solution under an applied magnetic field and a local self-referencing temperature sensing with excellent thermal sensitivity (1.64%·K^-1 (at 40 °C)) in the range 25-70 °C, good photostability, and reproducibility after several heating cycles.

Chemical sensors based on periodic mesoporous organosilica @NaYF4:Ln3+ nanocomposites

Here, three unique organic-inorganic hybrid nanocomposite materials prepared by combining NaYF₄:Yb³⁺,Ln³⁺ (Ln³⁺ = Er³⁺, Tm³⁺, Ho³⁺) and periodic mesoporous organosilica (PMO) are proposed for both metal ion sensing and solvent sensing. The luminescence properties of the developed hybrid materials, PMO@NaYF₄:Yb³⁺,Ln³⁺, were studied in detail in the solid state and after dispersing in water. It is found that PMO@NaYF₄:Yb³⁺,Er³⁺ showed selective "turn on" luminescence for Hg²⁺ with the detection limit of 24.4 μM in an aqueous solution. Additionally, the above three materials showed different luminescence emission responses towards water and organic solvents. It is worth noting that all three PMO@NaYF₄:Yb³⁺,Ln³⁺ materials showed "turn on" luminescence towards alcohols. PMO@NaYF₄:Yb³⁺,Er³⁺ and PMO@NaYF₄:Yb³⁺,Ho³⁺ were selected and further developed into sensitive sensors for the detection of water in alcohols by taking advantage of their quenching behavior in water. The detection limit for sensing of water was determined to be 0.21%, 0.18% and 0.29%, corresponding to isopropanol (PMO@NaYF₄:Yb³⁺,Er³⁺), n-butanol (PMO@NaYF₄:Yb³⁺,Er³⁺) and ethanol (PMO@NaYF₄:Yb³⁺,Ho³⁺), respectively. The above results illustrate the potential of these hybrid materials for applications in environmental fields as well as in chemical industries.

The importance, status, and perspectives of hybrid lanthanide-doped upconversion nanothermometers for theranostics

Theranostics combines diagnostics and therapy in a single multifunctional system. Multifunctional upconversion luminescent lanthanide-doped nanothermometers for theranostic purposes offer non-invasive and sensitive multimodal performance in the biomedical field over traditional temperature measurement methods. Despite existing challenges, various studies on hybrid upconversion nanothermometers show substantial progress for (bio)imaging, temperature sensing, photodynamic and photothermal therapy, as well as drug delivery applications. The beauty of such an approach is that it unfolds possibilities to combine diagnostics and therapy in a single particle, which can modify the way certain diseases are treated, hence change the entire healthcare scene.

Lanthanide-based metal-organic frameworks solidified by gelatin-methacryloyl hydrogels for improving the accuracy of localization and excision of small pulmonary nodules

The localization of invisible and impalpable small pulmonary nodules has become an important concern during surgery, since current widely used techniques for localization have a number of limitations, such as invasive features of hookwires and microcoils, and rapid diffusion after injection of indocyanine green (ICG). Lanthanide-based metal–organic frameworks (MOFs) have been proven as potential fluorescent agents because of their prominent luminescent characteristics, including large Stokes shifts, high quantum yields, long decay lifetimes, and undisturbed emissive energies. In addition, lanthanides, such as Eu, can efficiently absorb X-rays for CT imaging. In this study, we synthesized Eu-UiO-67-bpy (UiO = University of Oslo, bpy = 2,2'-bipyridyl) as a fluorescent dye with a gelatin-methacryloyl (GelMA) hydrogel as a liquid carrier. The prepared complex exhibits constant fluorescence emission owing to the luminescent characteristics of Eu and the stable structure of UiO-67-bpy with restricted fluorescence diffusion attributed to the photocured GelMA. Furthermore, the hydrogel provides stiffness to make the injection site tactile and improve the accuracy of localization and excision. Finally, our complex enables fluorescence-CT dual-modal imaging of the localization site.

Plugged bifunctional periodic mesoporous organosilica as a high-performance solid phase microextraction coating for improving extraction efficiency of chlorophenols in different matrices

In this study, a sensitive solid phase microextraction (SPME) coating was developed based on two kinds of plugged and non-plugged bifunctional periodic mesoporous organosilicas (BFPMO) with ionic liquid and ethyl units. The extraction efficiency of all plugged and unplugged sorbents was investigated for the extraction of chlorophenols (CPs) in water and honey samples by emphasizing the effect of different physicochemical properties. The separation and determination of the CPs was performed by gas chromatography-mass spectrometry (GC-MS). The extraction results showed that plugged BFPMO coating exhibited outstanding enrichment ability for the extraction of CPs as model analytes with different polarities. This can be attributed to a valuable hydrophobic-hydrophilic balance in the mesochanels of the plugged BFPMO, which is the result of the combination of plug technology and bridged organic groups. Low limits of detection in the range of 5-70 ng L^-1, wide linearity, and good reproducibility (RSD = 8.1-10.1 % for n = 6) under the optimized extraction conditions were achieved. Finally, the BFPMOs coated fiber was successfully used for determination of CPs in real water samples. The relative recoveries for the five CPs were in the range of 92.3-104.0 %, which proved the applicability of the method.

A new ionic liquid bridged periodic mesoporous organosilicas stationary phase for per aqueous liquid chromatography and its application in the detection of biogenic amines

In order to solve the problems of using a large proportion of acetonitrile on the hydrophilic interaction liquid chromatography (HILIC) columns that was not environmentally friendly, and the poor acid and base resistance of traditional bonded silica columns, we reported a novel stationary phase of Au nanoparticles (Au NPs) covalently bonded to ionic liquid (ILs) bridged periodic mesoporous organosilicas (PMO) hydrophilic microspheres (PMO-ILs-Au NPs) for per aqueous liquid chromatography (PALC). The PMO hydrophilic microspheres were prepared by condensation of 1,3-bis(trimethoxysilylpropyl)imidazoliumchloride and 1, 2-Bis (triethoxysilyl) ethane and then modified with Au NPs the surface. The obtained materials were characterized by elemental analysis, FT-IR spectra, scanning electron microscope and transmission electron microscopy. The retention behavior was evaluated by investigating the effect of various chromatographic factors on the retention of different types of solutes. The retention mechanism of the stationary phases in PALC was a mixed type of anion-exchange and hydrophobic interaction. Compared with C₁₈-SiO₂ column, the acid and base resistance of the stationary phase were greatly improved. Compared with the HILIC column and C₁₈ column, some hydrophilic compounds such as six organic acids and eight biogenic amines were baseline separated with the enhanced resolution of the PMO-ILs-Au NPs column under the PALC mode. The efficiency of the new column was significantly higher than that of the HILIC column. Furthermore, the analysis of PALC-triple quadrupole mass spectrometry was developed for simultaneous detection of eight biogenic amines. This method could improve detection efficiency, save reagent and reduce environmental pollution. PALC as a green chromatography analytical method was suitable for the replacement of HILIC.

Key Points in Remote-Controlled Drug Delivery: From the Carrier Design to Clinical Trials

The increased research activity aiming at improved delivery of pharmaceutical molecules indicates the expansion of the field. An efficient therapeutic delivery approach is based on the optimal choice of drug-carrying vehicle, successful targeting, and payload release enabling the site-specific accumulation of the therapeutic molecules. However, designing the formulation endowed with the targeting properties in vitro does not guarantee its selective delivery in vivo. The various biological barriers that the carrier encounters upon intravascular administration should be adequately addressed in its overall design to reduce the off-target effects and unwanted toxicity in vivo and thereby enhance the therapeutic efficacy of the payload. Here, we discuss the main parameters of remote-controlled drug delivery systems: (i) key principles of the carrier selection; (ii) the most significant physiological barriers and limitations associated with the drug delivery; (iii) major concepts for its targeting and cargo release stimulation by external stimuli in vivo. The clinical translation for drug delivery systems is also described along with the main challenges, key parameters, and examples of successfully translated drug delivery platforms. The essential steps on the way from drug delivery system design to clinical trials are summarized, arranged, and discussed.

Real-Time Temperature Monitoring of Photoinduced Cargo Release inside Living Cells Using Hybrid Capsules Decorated with Gold Nanoparticles and Fluorescent Nanodiamonds

Real-time temperature monitoring within biological objects is a key fundamental issue for understanding the heating process and performing remote-controlled release of bioactive compounds upon laser irradiation. The lack of accurate thermal control significantly limits the translation of optical laser techniques into nanomedicine. Here, we design and develop hybrid (complex) carriers based on multilayered capsules combined with nanodiamonds (NV centers) as nanothermometers and gold nanoparticles (Au NPs) as nanoheaters to estimate an effective laser-induced temperature rise required for capsule rupture and further release of cargo molecules outside and inside cancerous (B16-F10) cells. We integrate both elements (NV centers and Au NPs) in the capsule structure using two strategies: (i) loading inside the capsule's cavity (CORE) and incorporating them inside the capsule's wall (WALL). Theoretically and experimentally, we show the highest and lowest heat release from capsule samples (CORE or WALL) under laser irradiation depending on the Au NP arrangement within the capsule. Applying NV centers, we measure the local temperature of capsule rupture inside and outside the cells, which is determined to be 128 ± 1.12 °C. Finally, the developed hybrid containers can be used to perform the photoinduced release of cargo molecules with simultaneous real-time temperature monitoring inside the cells.

The Isocyanurate-Carbamate-Bridged Hybrid Mesoporous Organosilica: An Exceptional Anchor for Pd Nanoparticles and a Unique Catalyst for Nitroaromatics Reduction

Hybridisation of mesoporous organosilicas (MO) to reinforce the surface capability in adsorption and stabilisation of noble metal nanoparticles is of great attention in generating/supporting noble metal within their matrices and transforming them into efficient heterogeneous catalysts. Here, we used a unique hybrid of organic-inorganic mesoporous silica in which pore profile pattern was similar to the well-known mesoporous silica, SBA-15 for catalysis. This hybrid mesoporous organosilica was further engaged as a support in the synthesis and stabilisation of Pd nanoparticles on its surface, and then, the obtained Pd-supported MO was employed as a heterogeneous green catalyst in the conversion of aqueous p-nitrophenol (PNP) to p-aminophenol (PAP) at room temperature with efficient recyclability.

Overview of N-Rich Antennae Investigated in Lanthanide-Based Temperature Sensing

The market share of noncontact temperature sensors is expending due to fast technological and medical evolutions. In the wide variety of noncontact sensors, lanthanide-based temperature sensors stand out. They benefit from high photostability, relatively long decay times and high quantum yields. To circumvent their low molar light absorption, the incorporation of a light-harvesting antenna is required. This Review provides an overview of the nitrogen-rich antennae in lanthanide-based temperature sensors, emitting in the visible light spectrum, and discusses their temperature sensor ability. The N-rich ligands are incorporated in many different platforms. The investigation of different antennae is required to develop temperature sensors with diverse optical properties and to create a diverse offer for the multiple application fields. Molecular probes, consisting of small molecules, are first discussed. Furthermore, the thermometer properties of ratiometric temperature sensors, based on di- and polynuclear complexes, metal-organic frameworks, periodic mesoporous organosilicas and porous organic polymers, are summarized. The antenna mainly determines the application potential of the ratiometric thermometer. It can be observed that molecular probes are operational in the broad physiological range, metal-organic frameworks are generally very useful in the cryogenic region, periodic mesoporous organosilica show temperature dependency in the physiological range, and porous organic polymers are operative in the cryogenic-to-medium temperature range.

An "off-on-off" fluorescence chemosensor for the sensitive detection of Cu2+ in aqueous solution based on multiple fluorescence emission mechanisms

A new organosiloxane precursor ((E)-3-hydroxy-4-((2-(2-hydroxy-4-(3-(3-(triethoxysilyl)propyl)ureido)benzoyl)hydrazono)methyl)phenyl(3-(triethoxysilyl)propyl)carbamate, hereinafter referred to as AHBH-Si) and tetraethylorthosilicate (TEOS) were mixed as the mixed Si source, and bridged periodic mesoporous organic silica (AHBH-PMOs) nanoparticles were obtained through the co-condensation reaction. AHBH-PMO nanoparticles possess mechanisms of "Aggregation Induced Emission" (AIE) and "Intramolecular Charge Transfer" (ICT), which originate from the molecular structure of AHBH having "C[double bond, length as m-dash]N" bond, ortho hydroxyl groups, etc.. Therefore, the optical properties of AHBH are excellent with respect to the solvent effect and enhanced fluorescence. For hybrid materials, the silica framework provides a rigid environment that restricts the rotation of AHBH, thereby turning on the fluorescence of AHBH due to the regulation by the AIE effect. In particular, AHBH-PMOs are no longer restricted by organic solvents and could really achieve the response to Cu2+ with high sensitivity and selectivity in aqueous solutions of a wide pH range. In addition, the detection limit is as low as 3.26 × 10-9 M. Methods such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry have shown the coordination interaction between AHBH and Cu2+. The Gaussian 09 software of density functional theory to calculate the reducing changes of energy gaps among AHBH and AHBH-Si before and after the addition of Cu2+ showed that coordination interaction exists in the system. These results indicate that AHBH-PMO hybrid materials have potential applications in the field of environmental monitoring.

Luminescent PMMA Films and PMMA@SiO2 Nanoparticles with Embedded Ln3+ Complexes for Highly Sensitive Optical Thermometers in the Physiological Temperature Range*

In recent years, luminescent materials doped with Ln³⁺ ions have attracted much attention for their application as optical thermometers based on both downshifting and upconversion processes. This study presents research done on the development of highly sensitive optical thermometers in the physiological temperature range based on poly(methyl methacrylate) (PMMA) films doped with two series of visible Ln³⁺ complexes (Ln³⁺ =Tb³⁺ , Eu³⁺ , and Sm³⁺ ) and SiO₂ nanoparticles (NPs) coated with these PMMA films. The best performing PMMA film doped with Tb³⁺ and Eu³⁺ complexes was the PMMA[TbEuL₁ tppo]1 film (L₁ =4,4,4-trifluoro-1-phenyl-1,3-butadionate; tppo=triphenylphosphine oxide), which showed good temperature sensing of S_r =4.21 % K^-1 at 313 K, whereas for the PMMA films doped with Tb³⁺ and Sm³⁺ complexes the best performing was the PMMA[TbSmL₂ tppo]3 film (L₂ =4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadionate), with S_r =3.64 % K^-1 at 313 K. Additionally, SiO₂ NPs coated with the best performing films from each of the series of PMMA films (Tb-Eu and Tb-Sm) and their temperature-sensing properties were studied in water, showing excellent performance in the physiological temperature range (PMMA[TbEuL₁ tppo]1@SiO₂ : S_r =3.84 % °C at 20 °C; PMMA[TbSmL₂ tppo]3@SiO₂ : S_r =3.27 % °C at 20 °C) and the toxicity of these nanoparticles on human cells was studied, showing that they were nontoxic.

Highly selective fluorescence detection of Cu2+ based on Schiff base functionalized periodic mesoporous organosilicas

A novel copper ion sensing periodic mesoporous organosilica (SCN-PMO) was obtained by incorporating a Schiff base-based fluorescent receptor into the pore walls of mesoporous silica, which exhibited a well ordered mesoporous structure and excellent optical properties demonstrated by various characterization results. SCN-PMO possessed high selectivity and sensitivity towards Cu²⁺ based on its specific fluorescence response. The detection limit of SCN-PMO could be as low as 6.7 × 10^-7 M. Due to protection of the silica network, SCN chromophores in PMOs exhibited higher photostability and the resulting material possessed great repeatability. Additionally, the fluorescence changes of SCN-PMO towards copper ions in vivo (zebrafish) showed that SCN-PMO has potential application as a nanoprobe in biological fields.

Novel esterquat-based herbicidal ionic liquids incorporating MCPA and MCPP for simultaneous stimulation of maize growth and fighting cornflower

Modern agricultural practices are often based on the use of mixtures of specific herbicides to achieve efficient crop protection. The major drawbacks of commercial herbicidal formulations include the necessity to incorporate toxic surfactants and high volatility of active substances. Transformation of herbicides into herbicidal ionic liquids (HILs) seems to be a promising alternative which allows to almost completely reduce volatility due to ionic interactions. In the scope of this research, we transformed (2-methyl-4-chlorophenoxy)acetic acid (MCPA) into a quaternary ester (esterquat) with the use of derivatives of 2-dimethylaminoethanol. The obtained esterquats were later coupled with (±)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) in the form of an anion. The combination of MCPA and MCPA is commonly applied in the UK, EU countries and also in the USA to increase the spectrum of targeted weed species. In the framework of this study, novel HILs with an esterquat moiety incorporating a long alkyl chain (C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₄) were prepared and characterized in terms of basic physicochemical properties (solubility and volatility) as well as biodegradability. Their phytotoxicity was assessed towards cornflower (Centaurea cyanus) as a model weed and maize (Zea mays) as a crop plant. The presence of the esterquat cation contributed to satisfactory solubility in water and other low polar solvents, which eliminates the need to add exogenous adjuvants. Further experiments indicated that the tested HILs stimulated the germination stage of maize and maintained high herbicidal activity towards cornflower. No significant differences in terms of properties were observed in case of HILs which included alkyl substituents with an odd number of carbon atoms. Future studies should be focused on structural modifications in order to improve the biodegradability as well as field studies for evaluation of commercial applications.

Aqueous Systems with Tunable Fluorescence Including White-Light Emission for Anti-Counterfeiting Fluorescent Inks and Hydrogels

White-light-emitting materials have attracted wide interest for potential applications in information displays and lighting. To date, the majority of reported white-light-emitting materials have been multicomponent systems that are typically processed with organic solvents. These features are associated with complex processing, poor white-light quality, and environmental pollution. Herein, a white-light-emitting aqueous system is realized by encapsulating a fluorophore, which has a vibration-induced emission effect, in Pluronic F127 micelles. Tunable multicolor fluorescence is achieved by changing the temperature, and the use of organic solvents is effectively avoided. Through this process, white-light emission with Commission Internationale de l'Eclairage coordinates of (0.3351, 0.3326) is obtained, which is very close to pure white light, and its color rendering index is as high as 89. The fluorescence color tunability of this system could be performed in a wide temperature range, rendering it a potential material in optical thermometry. Besides, the aqueous system also allows for the application of the material as a fluorescent ink and white-light-emitting hydrogels. Information could be embedded in paper-based materials and hydrogels through the fluorescence quenching effect of iron ions (Fe³⁺) on the fluorophore. Fluorescence could then be recovered upon removal of Fe³⁺ by adenosine 5'-triphosphate. Thus, fluorescent patterning and triple-mode anti-counterfeiting could be expected due to the temperature-sensitive emission, fluorescence quenching, and recovering properties.

N-Rich Porous Polymer with Isolated Tb3+ -Ions Displays Unique Temperature Dependent Behavior through the Absence of Thermal Quenching

The challenge of measuring fast moving or small scale samples is based on the absence of contact between sample and sensor. Grafting lanthanides onto hybrid materials arises as one of the most promising accurate techniques to obtain noninvasive thermometers. In this work, a novel bipyridine based porous organic polymer (bpyDAT POP) was investigated as temperature sensor after grafting with Eu(acac)₃ and Tb(acac)₃ complexes. The bpyDAT POP successfully showed temperature-dependent behavior in the 10-310 K range, proving the potential of amorphous, porous organic frameworks. We observed unique temperature dependent behavior. More intriguingly, instead of the standard observed change in emission as a result of a change in temperature for both Eu³⁺ and Tb³⁺ , the emission spectrum of Tb³⁺ remained constant. This work provides framework- and energy-based explanations for the observed phenomenon. The conjugation in the bpyDAT POP framework is interrupted, creating energetically isolated Tb³⁺ environments. Energy transfer from Tb³⁺ to Eu³⁺ is therefore absent, nor energy back transfer from Tb³⁺ to bpyDAT POP ligand (i.e. no thermal quenching) is detected.

Ho3+-Yb3+ doped NaGdF4 nanothermometers emitting in BW-I and BW-II. Insight into the particle growth intermediate steps

Here, the excellent thermal sensing capability of Ho3+, Yb3+ doped β-NaGdF4 nanoparticles, where the system is excited into the 5F5 ← 5I8 transition of Ho3+ (640 nm), is reported. The ratio of the 2F5/2 → 2F7/2 transition peak of Yb3+ and the 5I6 → 5I8 transition peak of Ho3+ was employed for thermometry applications, resulting in a novel thermometer, which could potentially operate in BW-I and BW-II (BW - biological window). Additionally, interesting findings were made about the influence of the reaction time on the particle morphology and the presence of intermediate morphology forms.

Yb/Ho Codoped Layered Perovskite Bismuth Titanate Microcrystals with Upconversion Luminescence: Fabrication, Characterization, and Application in Optical Fiber Ratiometric Thermometry

Optical thermometry has attracted great interest owing to its noncontact and fast responsive properties in practical applications. However, some sensing errors may occur in many optical ratiometric thermometers due to the overlap of emission peaks, suggesting the necessity of developing excellent luminescent materials. Here, we report the fabrication and characterization of Bi₄Ti₃O₁₂:Yb/Ho for ratiometric thermometry. Bismuth titanate was selected as the matrix due to its low phonon energy, high machinability, and satisfactory thermal stability. The temperature sensing was constructed on the intensity ratio of the two upconversion emission bands with wide separation in Bi₄Ti₃O₁₂:Yb/Ho under 980 nm excitation. The wide separation endows the materials with high signal discrimination for temperature detection. The developed materials were characterized in terms of crystal structure, reflectance, and emission spectra for thermometry application. The maximum relative sensitivity was shown to be as high as 2.11% K^-1. More importantly, an optical fiber thermometry was developed based on the fabricated microcrystals, which can find its potential applications in harsh environments.