Luminescent Sensor Research Articles

Ultralong luminescence lifetime imaging of edible plant tissue for humidity sensing in food packaging by a smartphone

The safety of luminescence sensors and probes used in food packaging should be seriously considered, while most luminescence sensors were artificially synthesized with unclear toxicity, and cannot be directly used as indicators that were in contact with food. To overcome this problem, a humidity indicator based on an edible plant tissue was developed without any chemical processing. We found that garlic bulbs could emit significant persistent luminescence after drying at room temperature. The luminescence lifetime decreases from hundreds of milliseconds to tens of milliseconds as humidity increases. The long-lived luminescence could easily be detected through smartphones without any sophisticated instruments. The edible garlic is expected to be used as a humidity indicator in food packaging without worrying about food safety. Furthermore, the interference of scattered light and short-lived fluorescence from foods and packages can be eliminated in time-resolved luminescence imaging, greatly increasing the signal-to-noise ratio.

Remote optical thermometry by two-dimensional LiAl5O8:Cr3+ luminescence sensor probe

Pure-phase LiAl5O8:Cr3+ leaf-like particles were synthesized by combustion synthetic route at various concentrations. Both sharp peaks and broad emission photoluminescence are apparent even at room temperature. The most optimum doping concentration of 0.75 % based on lifetime and emission intensity was chosen. Peaks of different configurations were separated by deconvolution from 120 K to 680 K, where 4T2 peak increases in temperature to the expense of the sharp 2E emissions, giving luminescence intensity ratio (LIR) relative sensitivity of 2.8 % K−1 at room temperature. Large separation between Cr3+ R lines marks their LIR as perspective at low temperatures. At high temperatures luminescence lifetime provided for 0.8 % K−1 sensitivity, while line-shift and bandwidth methods are not sensitive enough for thermometric applications. Deconvolution of peaks enabled for 10 % more precise estimation of Debye temperature (679 K).

Thiazole-Decorated PCN-700 Metal–Organic Frameworks for Diclofenac Luminescence Sensing and Adsorption in Wastewater

Thiazole-Decorated PCN-700 Metal–Organic Frameworks for Diclofenac Luminescence Sensing and Adsorption in Wastewater

Thermosensitive chameleon films based on polystyrene doped with complexes of europium(III) and terbium(III)

New complexes of Eu(III) and Tb(III) tris(β-diketonates) with Lewis bases were synthesized. The spin-coating technique was used to produce composite films consisting of polystyrene (PS) polymer doped with mixtures of Eu(III) and Tb(III) complexes with different ratio of luminophores. An increase in the content of the Tb(III) complexes in the 5 %Eu x%Tb films intensifies emission of both the Tb3+ and Eu3+ ions due to occurring intermolecular energy transfer and leads to a significant increase in photostability of the material (the loss of luminescence intensity ratio did not exceed 0.5 %/hour). These photostable films were characterized as potential luminescent temperature sensors. The temperature sensitivity of their luminescence intensity and lifetime was investigated in the range of 298–383 K. The maximum absolute sensitivity of the films reaches 6.00 µs/K and exceeds that of all known lanthanide-containing thermal sensors designed for measuring physiological temperatures. In combination with changeable luminescence colors of the films, such a sensitivity makes these materials promising colorimetric thermal sensors for in situ temperature measurements.

Stimuli-responsive photoluminescent and structural properties of MIL-53(Al) MOF for sensing applications

Metal–organic frameworks (MOFs) are an intriguing group of porous materials due to their potential influence on the development of indispensable technologies like luminescent sensors and solid-state light devices, luminescent multifunctional nanomaterials. In this research work we explored MIL-53(Al), an exceptional class of MOF that, along with guest adsorption, undergoes structural transitions exhibiting breathing behavior between narrow pore and large pore under temperature and mechanical stress. Therefore, we opted for the time resolved luminescence and FT-Raman spectroscopy to investigate the mechanochromic and thermochromic response of this material under external stimuli. Intriguingly, when subjected to temperature changes, MIL-53(Al) exhibited a ratiometric fluorescence behavior related to the reversible relationship of photoluminescence emission intensity with respect to temperature. Moreover, under higher mechanical stress MIL-53(Al) displayed turn-on behavior in emission intensity, hence offering a thrilling avenue for the application in mechanically deformed-based luminescent sensors and ratiometric fluorescence temperature sensors.

Functional Construction of a Novel Lanthanide MOF for Efficient Ratio Luminescence Detection of Ethanol Vapor

AbstractIt is necessary to develop excellent sensors for volatile organic compounds (VOCs) detection from the perspective of environmental protection and human health. Luminescent lanthanide metal‐organic frameworks (MOFs) have many advantages such as porosity, luminescence, and structural controllability, making them very suitable as luminescent sensing materials. Based on a functional oriented strategy, novel Ln‐MOFs are successfully constructed and their structure and properties are characterized in detail. A series of vapor luminescence sensing tests have shown that Eu/Tb doped L1‐Eu0.1/Tb0.9 not only exhibits high selectivity for alcohols, especially ethanol vapor, but also has high sensitivity and extremely low detection limit (9.76 mg L−1). To the knowledge, there are no reports on ratio luminescence sensors based on Ln‐MOFs for ethanol vapor, especially those with such excellent performance. Crystal structure determination demonstrates that ethanol binds to the framework through multiple hydrogen bonding interactions, altering the energy transfer efficiency between Tb3+ and Eu3+ to achieve ratio luminescence detection. In addition, L1‐Eu0.1/Tb0.9 has good repeatability, the prepared thin film sensing material also demonstrates the advantages of portability and processability. This work can provide some experience for the development of VOCs sensing materials with better performance.

Non-invasive paper-based sensors containing rare-earth-doped nanoparticles for the detection of D-glucose

Today, diabetes mellitus is one of the most common diseases that affects the population on a worldwide scale. Patients suffering from this disease are required to control their blood-glucose levels several times a day through invasive methods such as piercing their fingers. Our NaGdF4: 5% Er3+, 3% Nd3+ nanoparticles demonstrate a remarkable ability to detect D-glucose levels by analysing alterations in their red-to-green ratio, since this sensitivity arises from the interaction between the nanoparticles and the OH groups present in the D-glucose molecules, resulting in discernible changes in the emission of the green and red bands. These luminescent sensors were implemented and tested on paper substrates, offering a portable, low-cost and enzyme-free solution for D-glucose detection in aqueous solutions with a limit of detection of 22 mg/dL. With this, our study contributes to the development of non-invasive D-glucose sensors, holding promising implications for managing diabetes and improving overall patient well-being with possible future applications in D-glucose sensing through tear fluid.

Pyrrole-substituted difluoroboron β-diketonate dyes: Facile synthesis and multi-state optical properties

Difluoroboron β-diketonate complexes (BF2bdks) are classic fluorescent molecules that have been applied in luminescent materials, oxygen and mechanical sensors, and most investigations concentrate on BF2bdks with varying aromatic groups without heteroatoms. In this work, a new molecular platform BF2bdks with heterocycle-substituted is prepared in one pot, and six unsymmetric π-expanded BF2bdks are synthesized via condensation reaction. B-1∼6 exhibit comparable fluorescence properties in solution, aggregated and solid states. B-3 (683 nm, Φf = 13.1 %) and B-5 (700 nm, Φf = 2.1 %) show near infra-red (NIR) emission with moderate fluorescence intensity in solution state. Solid emission of B, B-1-3 and B-5 are detected with fluorescence quantum yield from 12.8 % to 25.6 %, and B-2, B-3 and B-5 show AIE phenomenon in aggregated state. The results are supported by crystal analysis and DFT calculation in some extent. In a word, this work enriches the heterocycle-substituted BF2bdks system. B-3 and B-5 with moderate intensity NIR emission in solution, aggregated and solid states at the same time, providing a simple preparation method for multi-states luminescent dyes.

Dual-functional fluorescence sensors based on 3D lanthanide metal–organic framework and its mixed matrix membrane

A new lanthanide metal–organic framework (Ln-MOF) {[Eu(DPB)(H2O)](Me2NH2+)}n (1) (H4DPB = (1,1′:3′,1′’-terphenyl)-3,3′’,5,5′’-tetracarboxylic acid）was synthesized under solvothermal conditions and presented a fascinating three-dimensional (3D) framework with 4,8-connected diamond topology, which were built from Eu3+ ions and tetra carboxylate groups. 1 showed strong red luminescence emission in the solid state at room temperature and exhibited good stability in different solvents. 1 could be used as a multi-responsive luminescent sensor for hemin and p-Nitrophenol (4-NP) with detection limits of 3.91 × 10−6 M and 1.98 × 10−4 mM, respectively. Moreover, using 1 as a filler and poly (vinylidene difluoride) (PVDF) as matrix, a mixed matrix membrane 1@PVDF was successfully prepared. 1@PVDF also exhibited fluorescence emission comparable to that of 1 and could be used for hemin and 4-NP sensing with good selectivity and remarkable recyclability.

A novel strategy for the synthesis of samarium/europium-metal organic frameworks, and their utilization for detection of Cr3+, Pb2+, and acetone as a luminescent sensor with superior selectivity and sensitivity properties

With outstanding detection selectivity and sensitivity characteristics, samarium/europium-metal organic frameworks (Sm/Eu-MOF) is capable of functioning as a versatile light-emitting sensor particularly for detecting acetone, Cr3+, and Pb2+ in aqueous environment. While considering maximum detectable concentrations of 0.85 μM, 0.46 μM, and 1.04 μM, respectively, competitive energy interactions for acetone, absorption of energy for Cr3+, and substitution of ions for Pb2+ are the elucidated mechanisms of detecting these substances by Sm/Eu-MOF. Successful formulation and synthesis of a core–shell structured Sm/Eu-MOF, which has endurance to acid/alkali conditions and hydration/heat-stability, can be accomplished by utilizing Samarium and Europium nitrate ions, terephthalic acid, and 2, 5-furandicarboxylic acid. The recovery rate of acetone, Cr3+, and Pb2+ detection from real samples were 95.0–101.0 %, 99.8–101.0 %, and 99.9–104.0 %, respectively.

Two robust zinc(II) complexes as multi-functional luminescence sensor for detection of Fe3+, Cr2O72−, and CrO42− ions in water

Two new zinc(II) complexes, namely, [Zn(BBOP)(TPA)0.5]n (1) and [Zn(BBOP)(NDC)·H2O]n (2) (H2TPA = terephthalic acid, H2NDC = 1,4-naphthalene dicarboxylic acid, BBOP = 1,3-bis(benzimidazol-2-yl)-2-oxapropane) are hydrothermally synthesized and characterized. 1 features a 3D 2-fold interpenetrated 3-connected SrSi2-type framework. 2 is a mononuclear Zn(II) complex and further extend into the 3D supramolecular framework by OH⋯O and NH⋯O hydrogen bonding interactions. 1 and 2 both manifest high chemical stability. Two luminescence complexes are excellent sensors for the luminescent detection of Fe3+, Cr2O72−, and CrO42− ions in an aqueous medium. The quenching mechanism of the complexes is also investigated.

Hydrogen‐Bonded Organic Frameworks as an Appealing Platform for Luminescent Sensing

AbstractHydrogen‐bonded organic frameworks (HOFs), a novel subclass of porous crystalline materials self‐assembled from organic linkers through hydrogen bonding and other intermolecular interactions, have emerged as an exciting platform for developing multifunctional materials. Recently, luminescent HOF sensors have drawn considerable attention due to their unique advantages, such as hydrogen‐bonding flexibility, inherent luminescent centers in organic linkers, ease of functionalization, low density and toxicity, and good stability. However, a comprehensive study on the design strategies, functionalities, and applications of HOFs in sensing is lacking. In this review, the uniqueness and development of luminescent sensing HOFs are outlined. The design principles and strategies to enable the sensing performance are summarized, including the pre‐design of luminescent organic linkers and post‐modification with additional luminescent species. The state‐of‐the‐art advances in diverse sensing applications are overviewed, such as the detection of chemical pollutants, biomolecules, gases, and physical factors like temperature and mechanical forces. Moreover, the current challenges and corresponding potential avenues are discussed. This review aims to inspire more innovative research on the fabrication of advanced HOFs for luminescent sensing functions.

Indole-imidazole hybrid Schiff base for the selective detection of the explosive picric acid via fluorescence “turn-off” process: Experimental and theoretical DFT-D3 study

A compound containing a heteroatom and Schiff base, 3-(4,5-Diphenyl-1H-imidazol-2-yl)-1H-indole (INBIL) has been synthesized through the one-pot condensation of indole-3-carbaldehyde with benzil in ethanol and characterized using various analytical parameters like FT-IR, NMR; its thermal and chemical stability also established. The synthesized INBIL showed a 'turn off' luminescent property that has been used to detect picric acid. This luminescent sensor has a broad emission band at 415 nm in acetonitrile due to the conjugation of its double bond. It is worth noting that INBIL can be recycled through TEA treatment. The chemosensor exhibited the highest sensitivity with Ksv = 1.51 × 10−6 M, and a detection limit of 2.91 × 10−7 M, with perfect linearity up to 22 µL. The binding stoichiometry ratio between INBIL and picric acid was predicted to be 1:1 using Job's plot, which was confirmed by 1H NMR analysis. Finally, DFT-D3 calculations were used to calculate the excited molecule's singlet and triplet energy states.

Aggregation induced emission dynamic chiral europium(III) complexes with excellent circularly polarized luminescence and smart sensors

The synthesis of dynamic chiral lanthanide complex emitters has always been difficult. Herein, we report three pairs of dynamic chiral EuIII complex emitters (R/S-Eu-R-1, R = Et/Me; R/S-Eu-Et-2) with aggregation-induced emission. In the molecular state, these EuIII complexes have almost no obvious emission, while in the aggregate state, they greatly enhance the EuIII emission through restriction of intramolecular rotation and restriction of intramolecular vibration. The asymmetry factor and the circularly polarized luminescence brightness are as high as 0.64 (5D0 → 7F1) and 2429 M−1cm−1 of R-Eu-Et-1, achieving a rare double improvement. R-Eu-Et-1/2 exhibit excellent sensing properties for low concentrations of CuII ions, and their detection limits are as low as 2.55 and 4.44 nM, respectively. Dynamic EuIII complexes are constructed by using chiral ligands with rotor structures or vibration units, an approach that opens a door for the construction of dynamic chiral luminescent materials.

Eu(III) functionalized ZnMOF based efficient dual-emission sensor integrated with self-calibrating logic gate for intelligent detection of epinephrine

The rapid detection of epinephrine (EPI) in serum holds immense importance in the early disease diagnosis and regular monitoring. On the basis of the coordination post-synthetic modification (PSM) strategy, a Eu3+ functionalized ZnMOF (Eu3+@ZnMOF) was fabricated by anchoring the Eu3+ ions within the microchannels of ZnMOF as secondary luminescent centers. Benefiting from two independent luminescent centers, the prepared Eu3+@ZnMOF shows great potential as a multi-signal self-calibrating luminescent sensor in visually and efficiently detecting serum EPI levels, with high reliability, fast response time, excellentrecycleability, and low detection limits of 17.8 ng/mL. Additionally, an intelligent sensing system was designed in accurately and reliably detecting serum EPI levels, based on the designed self-calibrating logic gates. Furthermore, the possible sensing mechanisms were elucidated through theoretical calculations as well as spectral overlaps. This work provides an effective and promising strategy for developing MOFs-based self-calibrating intelligent sensing platforms to detect bioactive molecules in bodily fluids.

Layer‐By‐Layer Chiral Induction of Fluorene‐Based Metal–Organic Framework Films for Circularly Polarized Luminescence Sensing of Enantiomers

AbstractDeveloping films of chiral metal–organic frameworks (MOFs) with high circular polarization luminescence (CPL) is facing a great challenge for chiral sensing applications. Herein, a layer‐by‐layer chiral induction method is first reported to prepare enantiopure MOF films for CPL sensing. By layer‐by‐layer induction with the chiral inductor camphorsulfonic acid, fluorene‐based chiral MOF D/L‐ZnHF‐SO2 film (HF‐SO2 = 3,7‐Dibenzothiophenedicarboxylate, 5,5‐dioxide) with preferential growth orientation and homogeneous surface are prepared, which shows strong chiral feature and CPL with higher asymmetry factor of ±0.073. In addition, by mixed ligand approach, the isostructural fluorene ligand 9‐fluororenone‐2,7‐dicarboxylate is chosen to replace part of HF‐SO2 for preparing a series of chiral MOF films with tunable CPL emission. Furthermore, the prepared chiral MOF films with strong CPL performance are further utilized for enantiomers sensing. The CPL changes consisted with enantioselective adsorption results showed that D/L‐ZnHF‐SO2 film has good discrimination against chiral R/S‐phenylethylamine enantiomers, first reporting chiral MOF‐based candidates for the application in CPL sensing of enantiomers. This work provides a facile and effective approach for preparing chiral MOF films materials with high and tunable CPL performance, and also gives a new way to achieve CPL sensing of chiral enantiomers.

Application of Luminescent Effects In CdSe/CdS/ZnS Quantum Dots for the Determination of Sulphur-Containing Impurities in Mixtures of Hydrocarbons and Oils

The article is dedicated to the development of a new method for the sulphur-containing compound impurities analysis in mixtures of liquid hydrocarbons and corresponding oil fractions, based on the quenching of CdSe/CdS/ZnS quantum dots photoluminescence effect. The control of quantitative content of such impurities in oil samples is very important for the organization of the processes of its further processing and subsequent wide practical application. The work uses specially developed methods for the synthesis of CdSe/CDs/ZnS quantum dots, containing a semiconductor core, coated with a composite shell consisting of semiconductor and dielectric layers, as well as a fluorinated polymer porous layer. This technique made it possible to achieve a high quantum yield of photoluminescence (80–90) %, high temporal stability of luminescence in the range of (580–650) nm, as well as good compatibility of quantum dots with liquid hydrocarbon media. For the analysis, a special luminescent sensor was manufactured, which allows measuring the presence of organic sulphur-containing impurities with high sensitivity: (10–5 – 10–4) mg/kg. The technique is low-cost, allows the use of compact equipment and can be used to conduct operational analysis in real time.

Two 3D fsc-type hydrogen-bonded networks as luminescent sensors for turn-on sensing of tryptophan and aspartic acid

Two new luminescent coordination polymers (CPs), [M(Aze)(bmbp)]n (M = Zn for 1; Cd for 2), based on 4,4′-bis(2-methylimidazol-1-ylmethyl)biphenyl (bmbp) and azelaic acid (H2Aze) ligands have been hydrothermally synthesized. In their crystal structures, the metal centers are connected by bmbp and Aze2- to generate 1D chains, which are further linked by CH···O hydrogen bonds to form 3D supramolecular structures. Topological analysis suggests that the 3D hydrogen-bonded networks are binodal (4,6)-connected fsc nets with the symbol of (44·610·8) (44.62). CPs 1 and 2 both dispay excellent photoluminescence with good stability. Luminescent sensing experiments show that both 1 and 2 can be used as turn-on sensors to detect tryptophan (Trp) and aspartic acid (Asp) in aqueous solution. The limits of detections (LODs) toward Trp and Asp are 0.30 and 5.33 μM for 1, 0.23 and 2.62 μM for 2, respectively. Furthermore, the sensing mechanisms were also investigated in detail via various detection means and theoretical calculations. The test films of both CPs were also prepared for visual detection of Trp and Asp.

A water stable europium coordination polymer based on mixed organic ligands as a luminescence sensor for the detection of an anthrax biomarker

The development of luminescence sensors capable of detecting anthrax biomarkers is crucial for preventing anthrax. In this study, a two-dimensional europium coordination polymer [Eu(dlba)(phen)·2(H2O)]n (CP-1) was prepared based on a rigid 1,10-phenanthroline (phen) and a flexible 2-(3,5-dicarboxybenzyloxy) benzoic acid (H3dlba) under the hydrothermal conditions. The CP-1 was characterized by powder X-ray diffraction, elemental analysis, thermogravimetric analysis, infrared spectroscopy, and single crystal X-ray diffraction. The CP-1 exhibits excellent water stability and thermal stability. Luminescence experiments demonstrated a high luminescence quenching efficiency (98.1 %) upon addition of the anthrax biomarker dipicolinic acid (DPA). Additionally, the sensor shows good sensitivity and a rapid response time of 30 s. The detection limit is as low as 0.12 µM, which is much lower than the infection dose of spores (60 µM). The sensor has a recovery rate of 95–105 % when tested on actual samples, indicating its potential for practical applications. The luminescence quenching effect may be due to the competitive absorption of DPA, which affects the efficiency of energy transfer from the ligands to the europium ions.

A dual‐responsive luminescent sensor for efficient detection of 3‐nitrotyrosine and dipicolinic acid biomarkers based on copper(II) organic framework

The trace detection of biomarkers in real samples has profound a most important significance in the early diagnosis and daily monitoring of diseases. Based on the ligand pre‐design strategy, a novel 3D CuMOF, with the formula of {[Cu4(BTPB)(μ2‐OH)2(H2O)5]·3H2O}n, was fabricated by using the hexacarboxyl ligand of 1,4‐bis(2,4,6‐tricarboxylpyrid‐5‐yl)benzene (H6BTPB) and tetranuclear {Cu4(COO)4(μ2‐OH)2} SBUs. Benefiting from the robust framework and unique luminescence performance, the prepared CuMOF displays great potential as a dual‐responsive efficient luminescent sensor in “turn‐off” detection of 3‐nitrotyrosine (3‐NT) biomarker and “turn‐on” detecting the anthrax biomarker of dipicolinic acid (DPA), with detection limits (LOD) for 3‐NT and DPA being 110.8 ng/ml and 85.2 ng/ml, respectively. Additionally, the practicality and compatibility of such developed sensors were verified by quantifying 3‐NT and DPA biomarkers in diluted serum and urine samples with satisfactory recoveries. Further, the theoretical calculations of energy levels as well as the spectral overlap between the analytes and CuMOF were conducted to elucidate the possible sensing mechanisms. This work demonstrated that MOFs‐based luminescent sensors are evolving as an efficacious and equable approach for the detection of biomarkers in real samples.