Fluorescence Properties Research Articles

Bioplastic films from starch of Colocasia esculenta and its waste: A smart template for sensing applications

The over usage plastics have possessed serious threat to the ecological system. Thus progressive advancement in fabricating biodegradable and renewable bioplastics is persuasively required to furnish an effective alternative to non-biodegradable plastics. In this view, the current work highlights the production of starch based bioplastic films using waste Colocasia esculenta (taro herb) as a viable starting precursor. The functional ability of developed taro starch based film was further modified by incorporating carbon dots (CQDs) fillers generated from the waste slurry produced during starch extraction from taro herbs. The optimization of films production was achieved by varying the CQDs amount (0.4 %, 0.8 %, 2 % and 4 % w/w) on taro-based films using casting technology. The data illustrates that the addition of CQDs has the ability to enhance the fluorescence property, mechanical properties (Tensile Strength 0.332–4.635 MPa, Elongation at break 42.45–547.63 %) and water resistance ability of films (Moisture content 15–6.4 %, Water Solubility 50–30 % Water Vapour Transmission Rate 2.0012–1.0054 g−2 h−1 and Water Contact Angle 40.6–89.6°). The developed films are found to be thermally stable. The formed films possessed anti-oxidative abilities which safeguard the film from oxidative attacks and ultimately protect the film from the external environment. The fluorescence nanosensor probe has further been developed by utilizing CQDs embedded in a starch-based bioplastic nanocomposite. The developed sensor displayed selective sensing ability towards Fe2+ ion with high sensitivity and accuracy in aqueous medium. Thus, the proposed sensor in this work offers a portable, efficient, low-cost, disposable, non-lethal, and eco-friendly nanosensor for on-site monitoring of metal ion for the food, beverage, and pharmaceutical industries. This is one of the primary reports where metal ions sensing is reported for Taro@CQDs nanocomposites based films. Our outcomes of this work hold significant relevance to providing a smart sensory and biodegradable probe for metal ion sensing by using waste resources, thus offering a better and sustainable alternative for environmental remediation applications.

Starch-calcium inclusion complexes: Optimizing transparency, anti-fogging, and fluorescence in thermoplastic starch

With the increasing demand for anti-fogging transparent material and environmental concern, developing sustainable intrinsically hydrophilic and anti-fogging thermoplastic material is important. In this work, thermoplastic starch (TPS) films with good anti-fogging and optical properties were prepared via coordinative interactions with calcium chloride (CaCl2), zinc chloride (ZnCl2) and magnesium chloride (MgCl2). Among them, TPS with the incorporation of CaCl2 exhibited excellent anti-fogging and high optical transparency. Notably, the haze of TPS-0.2Ca just increased from 2.5 % to 3.8 %, with transparency remaining robust at 80 %. FTIR, XPS and 2D-WAXD results demonstrated the formation of inclusion complexes between Ca2+ and hydroxyl groups, which could modulate the hydrophobicity and hydrophilicity of TPS. Moreover, DMA, POM, and AFM results revealed that the formation of starch-calcium inclusion complex was crucial for achieving uniform intensity distribution, reduced crystalline areas, minimized light scattering, and decreased surface roughness, thereby contributing to the high transparency and low haze of TPS-Ca. Furthermore, TPS-Ca samples exhibited inherent fluorescent properties under UV light, showing the potential as disposable and eco-friendly fluorescence materials. This work provides new insights into design of sustainable TPS-based materials that combine robust antifogging performance with advanced optical property.

Response of Leaf Traits and Photosynthetic Fluorescence Characteristics of Fraxinus malacophylla Seedlings to Rainfall Patterns During Dry and Rainy Seasons in Southwestern China.

Global climate change has led to a shift in rainfall patterns. And as water is an essential ingredient for plant photosynthesis, shifts in rainfall patterns will inevitably affect plant growth. This study was conducted in Kunming, southwest China. In this study, the response of leaf traits and photosynthetic fluorescence properties of Fraxinus malacophylla seedlings to rainfall patterns during the dry and rainy seasons was investigated using a natural rainfall interval of 5 days (T) and an extended rainfall interval of 10 days (T+) as rainfall interval treatments and a monthly average rainfall as a control (W), with the corresponding rainfall treatments of a 40% increase in rainfall (W+) and a 40% decrease in rainfall (W-). The results showed that Pn, Gs, and Tr basically all tended to increase and then decrease with increasing rainfall in the dry season and generally reached the highest under the W treatment; Pn, Gs, Ci, and Tr mostly remained high at 5 days relative to 10 days; PI was overall higher under the W treatment throughout the dry season. Extending the rainfall interval at the beginning of the rainy season significantly reduced Fm; throughout the rainy season, Gs, Ci, and Tr basically showed a decreasing trend with increasing rainfall, reaching the highest under the W-treatment and mostly higher at 5 days than at 10 days. These results suggest that natural rainfall intervals and natural rainfall amounts are more favorable to the growth of Fraxinus malacophylla seedlings in the dry season; reduced rainfall and multiple rainfalls in the rainy season tend to promote photosynthesis in Fraxinus malacophylla. This study reflects the different survival strategies of Fraxinus malacophylla under different rainfall patterns, as well as provides a theoretical basis for understanding how Fraxinus malacophylla can grow better under rainfall variability and for future management.

Two lanthanide coordination polymers: syntheses, structures and selective detection of Fe3+, Cr2O72− / CrO42− and antibiotics

Two new lanthanide coordination polymers (CPs) [Tb(bptc)(4,4′-H2bipy)0.5·2H2O]n (1) and [Gd(bptc)(4,4′-H2bipy)0.5·2H2O]n (2) (H4bptc = 3,3′,4,4′-benzophenone tetracarboxylic acid, 4,4′-bipy = 4,4′-bipyridine) have been synthesized under solvothermal conditions. They were characterized by single crystal X-ray diffraction, elemental analysis, powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis. CPs 1 and 2 are isomorphous and display a 2D layer structure with the Schlafli symbol of {46·64}{47·63}. CP 1 exhibits excellent fluorescence properties, which can be used for sensitive and selective detection of Fe3+, Cr2O72− / CrO42− and antibiotics (tetracycline (TC), metronidazole (MDZ), and nitrofurazone (NFZ)) simultaneously. The possible luminescence sensing mechanisms were explored in detail. Cyclic experiments demonstrated that the fluorescence intensity of the CP 1 remained basically unchanged even after five cycles.

Computational insights into the photophysical processes of an acylhydrazone fluorescent probe based on conical intersection and sensing mechanism for Al3+ detection

Al3+ detection is crucial for food safety, environmental monitoring, and biological assays. This work investigated the fluorescent properties of the probe VN62 and its sensing mechanism for the detection of Al3+ ion in detail. The ground- and excited-state properties such as isomerization geometries and absorption spectra, as well as the photophysical processes of transitions in PES have been studied. There are few fluorescent S1 states (PT*, TICT) of the VN62 molecule, and the conical intersections (CIs) have key importance in the fluorescent process. By comparing the radiative rate (kr) and the rate of transition to CI, we deduce that these fluorescent states are lack of stability for light emission. Therefore, the fluorescence of probe alone can be quenched by CI pathways. After coordination with Al3+, the CI pathways will be suppressed, resulting in enhanced fluorescence. This sensing mechanism is different from the previously proposed mechanisms, such as the dark state of TICT or ESIPT. We anticipate that our research would shed some light on the design of turn-on sensors.

Doping of Mn2+ ion into boron quantum dots with enhanced fluorescence properties for sensing of L-thyroxine biomarker and bioimaging applications

L-thyroxine serves as a primary biomarker for diagnosing hypothyroidism and it is also utilized in hormone replacement therapy. Regular assessment of thyroxine levels is crucial for preventing health issues in hypothyroid patients, suggesting the requirement of a facile analytical tool for the detection of L-thyroxine. In this work, a straightforward and efficient synthetic method is introduced for in-situ preparation of Mn2+-doped boron quantum dots (Mn2+@B-QDs) derived from boron powder through a solvothermal reaction. The introduction of Mn2+ ion into B-QDs not only enhances fluorescence efficiency but also provides favorable sites within the QDs, expanding their potential applications in analytical chemistry. The blue fluorescent Mn2+ @B-QDs exhibited excellent performance for the selective recognition of L-thyroxine via a dynamic quenching mechanism. Under ideal conditions, a good linear relation was observed between the fluorescence emission intensity ratio of Mn2+@B-QDs and the concentration of L-thyroxine in the range of 0.125–5 μM, with a lower detection limit of 59.86 nM. The Mn2+@B-QDs exhibited the negligible cytotoxicity against A549 lung cancer cell lines and demonstrated good biocompatibility toward Saccharomyces cerevisiae cells.

Ultrasound synthesis of lanthanide complexes: Crystal structure, thermal decomposition kinetics and fluorescence properties

Two binuclear complexes were successfully synthesized by ultrasound method:[Ln(2-Cl-6-FBA)3(5,5′-DM-2,2′-bipy)(H2O)]2, (Ln=Tb(1), Dy(2); 2-Cl-6-FBA=2‑chloro-6-fluorobenzoicacid; 5,5′-DM-2,2′-bipy=5,5′-dimethyl-2,2′-bipyridine). The crystal structure analysis showed that the two complexes were isomorphic. And they were characterized by IR spectra, Raman spectra and XRD. The fluorescence properties of complex 1 were studied and its luminescence lifetime was calculated. Subsequently, the heat capacity of the two complexes were measured and their thermodynamic functions were obtained. TG-DTG/FTIR/MS technique was used to test the thermal decomposition of the complex in order to better understand the thermal decomposition behavior. Complex 1 was tested at different heating rates to study its non-isothermal kinetics. The relationship between activation energy E and conversion rate α was calculated by M. J. Starink method and NL-INT method. The mechanism functions in the third step decomposition process were determined by double equal-double steps method as G(α) = 1-(1-α)1/2 and f(α) = 2(1-α)1/2. The activation energy E and the pre-exponential factor A were calculated, a series of thermodynamic parameter of the complex were obtained by the equations.

A chitosan-based near-infrared ratiometric fluorescent nanoprobe created by molecular assembly with applications in hypochlorous acid detection in live mouse

Hypochlorous acid (HClO/ClO−) is a key reactive oxidative species (ROS) in the body. The HClO/ClO− concentrations are imbalanced during cancer formation due to the ROS stress response. This paper introduces a novel chitosan-based self-calibration fluorescent nanoprobe (ChCyNil) constructed by molecular assembly for the ratiometric detection of HClO/ClO−. Two chromophores with different fluorescence characteristics and HClO/ClO− sensitivity were labeled on chitosan, and nanoparticles were prepared by a self-assembly strategy for HClO/ClO− detection. ChCyNil exhibits several advantages, such as dual near-infrared emissions at 670 nm and 845 nm, tunable fluorescence intensity, self-calibration fluorescence, and good biocompatibility, improving its accuracy in HClO/ClO− detection. Our study confirmed that ChCyNil exhibits a well-assembled spheroidal nanostructure and good photophysical properties in solution. The fluorescence imaging properties were further proved by detecting endogenous HClO/ClO− produced by LPS/PMA stimuli in cells and zebrafish. In addition, ChCyNil was used to detect the fluorescence behavior of HClO/ClO− in tumors of live mice. The successful design and fabrication of ChCyNil have presented a new strategy for constructing detection tools with improved fluorescence properties for HClO/ClO− in live animals.

Interaction of Tri-Cyclic Nucleobase Analogs with Enzymes of Purine Metabolism: Xanthine Oxidase and Purine Nucleoside Phosphorylase.

Fluorescent markers play important roles in spectroscopic and microscopic research techniques and are broadly used in basic and applied sciences. We have obtained markers with fluorescent properties, two etheno derivatives of 2-aminopurine, as follows: 1,N2-etheno-2-aminopurine (1,N2-ε2APu, I) and N2,3-etheno-2-aminopurine (N2,3-ε2APu, II). In the present paper, we investigate their interaction with two key enzymes of purine metabolism, purine nucleoside phosphorylase (PNP), and xanthine oxidase (XO), using diffraction of X-rays on protein crystals, isothermal titration calorimetry, and fluorescence spectroscopy. Crystals were obtained and structures were solved for WT PNP and D204N-PNP mutant in a complex with N2,3-ε2APu (II). In the case of WT PNP-1,N2-ε2APu (I) complex, the electron density corresponding to the ligand could not be identified in the active site. Small electron density bobbles may indicate that the ligand binds to the active site of a small number of molecules. On the basis of spectroscopic studies in solution, we found that, in contrast to PNP, 1,N2-ε2APu (I) is the ligand with better affinity to XO. Enzymatic oxidation of (I) leads to a marked increase in fluorescence near 400 nm. Hence, we have developed a new method to determine XO activity in biological material, particularly suitable for milk analysis.

A high toughness hydrogel with Dy3+ enhanced fluorescence properties: For visual Zn2+ detection

Rapid, portable, and sensitive detection of Zn2+ is crucial for human health. In this study, SA/PEG/Ln fluorescent hydrogels were synthesized via in situ polymerization with lanthanide metals (Tb3+/Dy3+) and PAM. The results demonstrated a significant improvement in mechanical properties (132.8 % increase in compressive properties) after rare earth doping. The addition of Dy3+ enhanced the fluorescence properties of the singly doped Tb3+ fluorescent hydrogel (maximum luminous intensity increased by 1900 cd). Monitoring changes in fluorescence intensity enabled the realization of Zn2+ detection, allowing for quick and accurate determination of zinc ion presence. Visual monitoring of Zn2+ was achieved with the assistance of a portable ultraviolet lamp.

Multifunctional honeysuckle extract/attapulgite/chitosan composite films containing natural carbon dots for intelligent food packaging

In order to fulfill people's requirements for food quality and safety, it is a promising strategy to develop intelligent biodegradable food packaging materials. Herein, honeysuckle extracts/attapulgite/chitosan composite films containing natural carbon dots were fabricated for intelligent food packaging. Different characterization techniques were employed to study the obtained composite films, while the physicochemical properties, optical properties, antibacterial and antioxidant activities of composite films were determined. The obtained composite films presented good mechanical, antibacterial and antioxidant properties, and the antibacterial ratios of composite films against Escherichia coli and Staphylococcus aureus were 99.27 ± 0.18 % and 98.85 ± 0.65 %, respectively. When the added amount of honeysuckle extracts/attapulgite nanocomposites was 4.76 %, the tensile strength and elongation at break of composite films reached 24.9 ± 2.35 MPa and 64.8 ± 2.11 %, respectively, which were obviously higher than that of pure chitosan film. Furthermore, the composite films exhibited excellent UV shielding and blue fluorescence properties, as well as pH-sensitivity due to the presence of caffeoquinic acid-based natural carbon dots derived from honeysuckle extract. Therefore, the composite films indicated a potential application for intelligent food packaging.

Establishment of appropriate conditions for the efficient determination of multiple mycotoxins in tea samples and assessment of their drinking risks

Conditions were determined for rapid, convenient, and efficient determination of 16 common mycotoxins in tea samples. Mycotoxins in tea leaves and tea infusion samples were extracted using solid-liquid extraction/liquid-liquid extraction combined with ultrasonic-assisted extraction. The extraction solvent was 2-butanone/ethyl acetate (9/1 v/v) with 0.1 % formic acid. The established conditions enabled the analysis of these mycotoxins by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) in 5.5 min. In addition, HPLC with a temperature-controlled fluorescence detector was able to simultaneously determine 8 mycotoxins with fluorescent properties in 10 min without derivatization. Aflatoxin M1 (2.15 and 3.01 μg/kg), fumonisin B2 (198.89 μg/kg), and zearalenone (87.54 μg/kg) could be detected in commercially available pu-erh tea, green tea, and black tea products, and their total transfer rates from the products to brewed tea infusions were 64.08–65.13 %, 90.59 %, and 25.99 %, respectively. The risks of drinking mycotoxins from these tea infusions mostly showed low levels of concern.

Water-Soluble AIE Photosensitizer in Short-Wave Infrared Region for Albumin-Enhanced and Self-Reporting Phototheranostics

Organic photosensitizers (PSs) play important roles in phototheranostics, and contribute to the fast development of precision medicine. However, water-soluble and highly emissive organic PSs, especially those emitting in the short-wave infrared region (SWIR), are still challenging. Also, it's difficult to prepare self-reporting PSs for visualizing the treatment via stimulated emission depletion (STED) nanoscopy. Thus, in this work, a water-soluble molecule of DTPAP-TBZ-I with aggregation-induced emission features is designed for the self-reporting photodynamic therapy (PDT) in an ultra-high resolution. In contrast to single molecule, its complex (DTPAP-TBZ-I@BSA) shows much enhanced fluorescence properties and reactive oxygen species (ROS) generation in SWIR window. Their photoluminescence quantum yield is determined to be ∼20.6 % and the enhancement of ROS generation is ∼18-fold. During the PDT, immigration of the complex from cytoplasm to nucleus is also observed via STED nanoscopy with a resolution of 66.11 nm, which allows self-report in the PDT treatment. DTPAP-TBZ-I@BSA is finally utilized for the imaging-guided PDT in vivo with a tumor inhibition rate of 84 %. This is the first work in albumin-enhanced water-soluble organic PSs in SWIR window for self-reporting phototheranostics at ultra-high resolutions, providing an ideal solution for the next generation of photosensitizers for precise medicine.

Facile synthesis and tunable fluorescent properties of a new D-π-A isocoumarin: Applications in encryption and OLED technology

A facile synthesis of a new D-π-A isocoumarin (ICP-NH2) with only two steps under mild conditions through O-acylation/Wittig/reduction reaction has been established. The readily accessible phosphonium salt precursor 1 and 4-nitrobenzoyl chloride 2 produced intermediate ICP-NO2 in the presence of triethylamine. Subsequently, ICP-NO2 underwent conversion to ICP-NH2 through the reduction of stannous dichloride. ICP-NH2 exhibits enhanced fluorescence overcoming the photo-induced electron transfer (PET) process in ICP-NO2. ICP-NH2 demonstrates a significant change in fluorescence from blue to green in various polar solvents, and DFT analysis confirmed that its solvatochromism is attributed to intramolecular charge transfer (ICT) effect. ICP-NH2 undergoes noticeable acidochromism based on reversible protonation and deprotonation reactions with TFA and TEA, leading to periodic changes in fluorescence from green to dark blue. This phenomenon can be utilized in designing reusable encryption technology. Additionally, ICP-NH2 can be employed in the fabrication of a cyan green OLED device.

High-sensitivity ferrous sulfate dosimeters with wide dosimetry range based on fluorescence properties of gold nanoclusters

With the widespread application of nuclear technologies, radiation dose measurement is important. Ferrous sulfate dosimeters are common chemical dosimeters, but their high detection limit and narrow dosimetry range limit their application in some fields. In this work, we introduce a novel dosimetry approach for ferrous sulfate dosimeters utilizing the fluorescence properties of gold nanoclusters (AuNCs) capped with histidine. The Fe2+ ions in the ferrous sulfate dosimeter are oxidized to Fe3+ ions during irradiation. The presence of Fe3+ ions results in the fluorescence quenching of AuNCs, establishing a correlation between the fluorescence intensity of the dosimeter and irradiation doses. The lowest detection limit of the fluorescence dosimeter was found to be 2 Gy. Moreover, the dose response of the dosimeter showed good linearity within the dose range of 2–400 Gy. The dosimetric sensitivity of the fluorescence dosimeter was 17.9% higher than that of ultraviolet–visible spectroscopy. The results indicate that the dosimetry method utilizing the fluorescence properties of AuNCs significantly improves the detection sensitivity and detection limit of the dosimeter. Our work provides a new dosimetry method for ferrous sulfate dosimeters that can be used in a wider range of irradiation situations.

Structural Comparisons, Fluorescence Properties, and Glass-to-Crystal Transformations of Heat-Cooled and Melt-Quenched Zeolitic Imidazolate Framework Glass.

As a representative of zeolitic imidazolate framework glass, agZIF-62 has been reported to be synthesized using a melt-quenching method in which the ZIF-62 crystal is heated to a temperature above the melting point. Interestingly, we unexpectedly found that agZIF-62 can also be synthesized by simple heating at temperatures lower than the melting point, which may be assisted by the release of encapsulated solvent molecules. The structural differences between melt-quenched agZIF-62 (MQ-agZIF-62) and heat-cooled agZIF-62 (HC-agZIF-62) were investigated. The results indicated that MQ-agZIF-62 is closer to the liquid state, while HC-agZIF-62 is closer to the crystal state. Interestingly, their luminescent emissions exhibit significant differences. Compared with the ZIF-62 crystal, MQ-agZIF-62 showed a blue-shift of 14 nm, whereas HC-agZIF-62 showed a red-shift of 9 nm. The emission intensity of agZIF-62 is also significantly stronger than that of ZIF-62; thus, rapid semiquantitative detection of the content of the MOF glass in glass and crystal mixtures can be achieved. In addition, HC-agZIF-62 and MQ-agZIF-62 can transform into ZIF-62 crystals via a solvent-media mechanism. This study provides new insights into ZIF-62 glass.

Dual-Template-Directed Zero-Dimensional Bismuth Chlorides: Structures, Luminescence, Photoinduced Chromism, and Enhanced Proton Conductivity.

Zero-dimensional (0D) hybrid organic-inorganic bismuth halides have attracted immense scientific interest as promising candidates for lead-free materials. Here, by using a typical solvothermal method, two mixed-cation-phase 0D hybrid bismuth chlorides of [HPDA][H2PDA]BiCl6 (1) and [Hbzim][H2PA]BiCl6 (2) (PDA = bis(4-pyridyl)amine, bzim = benzimidazole, PA = 2-picolylamine) have been assembled based on a series of organic amine guests. Both compounds exhibit interesting photoluminescence phenomena, in which compound 1 exhibits a double emission property of blue fluorescence and yellow-green phosphorescence simultaneously, while compound 2 exhibits wide-band yellow-green emission under visible light excitation. The luminescence mechanism is explained by experiments and theoretical calculations. In view of the fact that halometallate units and the conjugated nitrogen heterocyclic systems can act as electron donors and electron acceptors, respectively, both compounds exhibit free radical-driven photochromism induced by electron transfer under xenon lamp irradiation at room temperature. In addition, benefiting from abundant hydrogen bond networks in structures, the two compounds show significant temperature-dependent proton conduction behavior in the range of 298-343 K, and the proton conductivity of both compounds is significantly improved after light irradiation. Our study demonstrates two novel hybrid mixed-cation-phase 0D hybrid bismuth halides with photoluminescence, photochromism, and photomodulated proton conduction properties, which enriches the dual-template-directed metal halide system and provides a feasible scheme for the synthesis of photoresponsive smart materials.

Gram-Scalable Solvent-Free One-Pot Three-Component Synthesis of 2-Arylamino-3-Cyanopyridines

Organic compounds that can show fluorescence are utilized for numerous applications. Scalable synthetic routes for such compounds are a great part of academic as well as technological investigations in this area. In addition to fluorescent properties, pyridine compounds have been proven for other applications, especially in biological studies. A one-pot synthetic procedure is presented and 16 (14 new) compounds of the 2-arylamino-3-cyanopiridine family are being reported for the first time. Analytical methods including CHN, NMR (1H and 13C), IR, and MS were used to characterize the newly reported compounds. They all show blue to green fluorescence when irradiated with UV light. A scalable approach is also presented with more than 95% yield for obtaining these compounds with a fairly facile workup.

Flexible AIE/PCM composite fiber with biosensing of alcohol, fluorescent anti-counterfeiting and body thermal management functions

Alcohol sensing plays a critical role in medical detection and personal health management. AIE materials with high sensitivity, selectivity and fast response have been widely used in biosensing, but their application in the field of alcohol sensing still needs further research and development. Furthermore, developing flexible phase change materials (PCMs) is significant for the research of human-body thermal management. In this study, a kind of flexible polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP)/polyethylene glycol (PEG)/Py-CH (pyrene-based AIE molecule)/SiO2@h-BN composite fiber textile (PAB) with alcohol sensing performance, writable fluorescence property, and human body thermal management function has been prepared via electrospinning technique. The PAN/PVP fiber matrix successfully integrated AIE fluorescent sensing material and PCM into a multi-functional composite with great shape stability. Owing to the introduction of novel pyrene-based Py-CH with AIE characteristic, this innovative textile exhibited wonderful fluorescent properties, including sensitive alcohol fluorescence sensing, writable fluorescence performance and variable temperature fluorescence. Furthermore, proposed PAB textile delivered a high energy storage density of 87∼90 J/g, excellent thermal reliability, great comprehensive mechanical flexibility and enhanced thermal conductivity for flexible human body thermal management. Hence, this flexible multifunctional AIE/PCM composite sensing textiles can be widely used in alcohol sensing, fluorescence anti-counterfeiting and flexible body thermal management.

Hydroxyl-driven construction of dual-emitting CsPbBr3/EuWO4(OH) composite for radiometric thermometer and information encryption applications

Self-assembled inorganic metal halide perovskite composites with high emitting efficiency, tunable multimode emission and stimuli-responsive luminescence demonstrated great potential in diversified luminescence applications. Here, a novel CsPbBr3/EuWO4(OH) composite was successfully prepared through the surface adsorption of Pb2+ ions on hydroxylated EuWO4(OH) microsheets and subsequent nucleation of CsPbBr3 peroviskite quantum dots (PQDs) by the anti-solvent crystallization in CsBr containing N,N-dimethylformamide (DMF) solution. Due to the distinct fluorescent thermochromic switching properties of temperature-insensitive Eu3+ and sensitive CsPbBr3 PQDs emitting centers, the resultant CsPbBr3/EuWO4(OH) composite exhibits excellent ratiometric temperature sensing performance. The CsPbBr3/EuWO4(OH) thermometer based on the fluorescence intensity ratio (FIR) technique originating from emissions of Eu3+ to CsPbBr3 PQDs was then explored with a high temperature sensitivity (Sr) of 5.8 % ℃−1 at 54 ℃. In addition, a high-security-level information encryption scheme was proposed by utilizing the excitation-wavelength-dependent switchable fluorescence of CsPbBr3/EuWO4(OH) composite. This study provides a simple and feasible strategy for assembling dual-emission CsPbBr3/EuWO4(OH) composite, showing potential applications in optical ratiometric thermometry and information encryption fields.