Luminescent Sensor Research Articles

Ratiometric visualization fluorescence temperature sensing based on dual-lanthanide metal-organic frameworks

High-performance optical temperature sensors play an important role in various fields, and lanthanide metal-organic frameworks (Ln-MOFs) are expected to be luminescent temperature sensors due to their distinctive luminescent properties. Herein, a new three-dimensional (3D) Ln-MOF [Tb(TCA)(Phen)]·DEF (1) (H3TCA = 4,4′,4′'-nitrilotribenzoic acid, Phen = 1,10-phenanthroline, DEF= N, N-diethylformamide) is constructed with a rtl topology based on {Tb2(COO)4} secondary building units (SBUs). Meanwhile, dual-lanthanide Ln-MOFs [TbxEu1-x(TCA)(Phen)]·DEF (2-6) are also synthesized by varying the ratio of Tb3+: Eu3+ in the reaction mixture, which can be applied in practical LED applications originating from their visual luminescent color changes. Among them, 4 is an efficient ratiometric fluorescent thermometer over a wide temperature range from 283 to 393 K and has a large relative sensitivity Sr of 4.2407 % K−1 at 393 K with good repeatability. Furthermore, the emission color of 4 gradually changes from yellow (283 K) to orange-red (393 K) as temperature increases for visual colorimetric temperature measurements, which attributed to the energy transfer between Tb3+ and Eu3+ ions.

Two water-stable Cd(II)-based coordination compounds as a fluorescent sensor for selective and sensitive detection of antibiotics

Developing highly stable materials for harmful compound detection in a water environment is of much importance and challenge. we report two cadmium based fluorescent coordination compounds with formula [Cd(HL)(phen)(H2O)3] (1) and [Cd(HL)(2,2′-bipy)(H2O)2] (2) where H3L = 4-(N,N’-bis(4-carbonylbenzyl)amino)-3-methylbenzenesulfonic acid, phen = 1,10-phenanthroline monohydrate and 2, 2′-bipy = 2, 2′-bipyridine. Details structural studies showed that compounds 1 and 2 are mononuclear and binuclear discrete compounds, respectively. Its excellent luminescence stability in aqueous solutions, coupled with outstanding thermal and chemical stabilities, enables it to function as an efficient detector for metamitron (MMT). It boasts a limit of detection of 2.72 ppm and exhibits quenching constant (KSV) values of 0.09, making it an effective luminescent sensor for detecting MMT. The luminescence quenching of the compound 1 by MMT was attributed to competing absorption and photoelectron energy transfer mechanisms.

Two Three-Dimensional LnIII Coordination Polymers Exhibiting Luminescent Sensing and a Magnetocaloric Effect.

Two lanthanide 3D coordination polymers [Ln2(L)4Cl2(H2O)4]n (Ln = Eu (1), Gd (2)) with quinoline-2-carboxylic acid (HL) as the ligand were successfully synthesized and characterized. Complex 1 exhibits a highly sensitive and selective luminescent response to 2,6-dipicolinic acid (DPA) in tap water and is virtually unaffected by interferences such as amino acids, aromatic carboxylic acids, and ions. With the addition of DPA, the luminescence intensity of complex 1 decreases rapidly to the naked eye. The detection limit of 1 toward DPA is 3.36 μM, which is much less than the infectious dose (60 μM) of the anthrax spores, indicating the high sensitivity of 1 to DPA. This study offers a basis for employing lanthanide complexes in real sample analysis, enabling direct and efficient detection of DPA with high sensitivity and specificity. Additionally, it is noteworthy that at a magnetic field strength of 7 T and a temperature of 3 K, the maximum entropy change for complex 2 attains a value of 23.56 J kg-1 K-1.

New robust 2D cobalt (II) coordination polymer as an effective turn-on luminescent sensor to detect Tb3+ and pefloxacin

It is necessary to employ highly sensitive and rapid detection of antibiotics and heavy ions in the environment. A mixed-ligands ternary Co (II) coordination polymer containing new L ligands, {[Co(L)(mip)(H2O)]·2H2O}n (1), (L = 2,2′-bis-(2-pyridin-3-yl-vinyl)-3H,3′H-[5,5]bibenzoimidazole, H2mip= 5-methylisophthalic acid) was synthesized under solvothermal condition. Compound 1 displays a sql 2D layer with the point symbol of {44.62}. Compound 1 owns excellent thermal and pH stability and can effectively sensitize the luminescence of Tb3+ ions through the “antenna effect”. Compound 1 can serve as luminescent probe for detecting pefloxacin and Tb3+ with low detection limits. Especially Compound 1 is the first turn-on sensor for the detecting Tb3+ ions and pefloxacin via fluorescence enhancement. In addition, the sensing mechanism is discussed in detail.

Enhancement of Excimer Formation Ability by Modulating the Length of Side-Chains in Polyhedral Oligomeric Silsesquioxane (POSS) and Application for Fluorescence Sensors for Metal Cations

Abstract Polyhedral oligomeric silsesquioxane (POSS) is a molecule with an inorganic cubic structure and organic side-chains and has attracted great attention for its application to luminescent materials by modifying luminophores. In this study, pyrenes-integrated POSSs with various lengths of side-chains were synthesized and the effect of the length on luminescent properties was evaluated. In optical measurements, highly efficient excimer emission was observed under dilute solution conditions. The higher value of the intensity ratio of the excimer emission to the monomer one was detected in the shortest side-chains. It is likely that the shorter side-chains of POSS lead to more efficient intramolecular interaction. Interestingly, we also found that the luminescence color was changed in response to metal cations in the dilute solutions. From the mechanistic study, metal cations such as Cu2+ can accelerate hydrolysis at the linker moiety. As a result, highly-sensitive luminescent sensors were obtained. These data represent that POSS can work as a reaction field where chemical reactions are accelerated through the accumulation of reactive species.

Hydrogen‐Bonded Organic Frameworks as an Appealing Platform for Luminescent Sensing (Adv. Funct. Mater. 26/2024)

Hydrogen‐Bonded Organic Frameworks as an Appealing Platform for Luminescent Sensing (Adv. Funct. Mater. 26/2024)

Two Water-Stable Zn(II) Coordination Polymers as Luminescent Sensors for Detection of Uric Acid in Serum, MnO4–, and Cr(VI) Oxo-Anions in Tap Water

Two Water-Stable Zn(II) Coordination Polymers as Luminescent Sensors for Detection of Uric Acid in Serum, MnO₄^–, and Cr(VI) Oxo-Anions in Tap Water

2D Zn (II) Metal‐Organic Framework as a Highly Sensitive Luminescent Sensor for Detection of the Cr2O72− and Fe3+

AbstractIn this work, NH2‐containing organic ligand 5‐Aminoisophthalic acid (AIPA), and trans‐1,2‐bis(4‐pyridyl)ethene (bpe) were selected as organic ligands to construct a new two‐dimensional luminescent Zn(II) metal‐organic framework [Zn(AIPA)(bpe)1/2]⋅named MOF‐1. It is worth noting that MOF‐1 exhibited excellent thermal stability and chemical stability in common solvents and different pH aqueous solution. As we expected, the luminescence sensing investigations demonstrated that MOF‐1 could be deemed as a multifunctional fluorescence sensor toward Cr2O72− and Fe3+ via a “turn‐off” effect. Notably, MOF‐1 had high selectivity and sensitivity for Fe3+ and Cr2O72− with low detection limits of 9.72×10−5 M and 1.95×10−5 M, respectively. Furthermore, the possible quenching mechanisms were also explored in detail.

Highly Selective Ratiometric Sensors for Pb2+ Based on Luminescent Zn(II)-Coordination Polymers with Thiophenedicarboxylate. Crystal Structures and Spectroscopic Studies.

The development of luminescent coordination polymers for the selective sensing of Pb2+ in water constitutes an active area of research that impacts analytical, environmental, and inorganic chemistry. Herein, two novel water-stable 2D Zn-coordination polymers {[Zn2(H2O)2(tdc)2(bpy)]·(H2O)}n 1 and [Zn(tdc)(tmb)]n 2 (tdc = thiophenedicarboxylate; bpy = 4,4'-bipyridine and tmb = 4,4'-trimethylenebipyridine) were synthesized, structurally determined by single crystal X-ray diffraction, and studied in-depth as luminescent sensors for a series of cations (Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ Cd2+, Hg2+ and Pb2+) in 20% aqueous ethanol. These Zn-polymers possess photostability in 20% aqueous ethanol with a strong emission at 410 upon excitation at 330nm and quantum yields of around Φ = 0.09. Under these conditions, Pb+2 can be efficiently sensed with polymer 2 through a fluorescent ratiometric response with selectivity over common interfering metal ions such as Cu2+, Cd2+ and Hg2+ in the micromolar concentration range (detection limit = 1.78 ± 10μM). Such selectivity/affinity of Pb2+ over Hg2+ for luminescent chemosensors is still rare. On the basis of spectroscopic tools (1H NMR, far ATR-IR, PXRD), the X-ray crystal structure of 2, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopic analysis, the ratiometric fluorescent response is proposed via an efficient metal-ion exchange driven through interactions between thiophenedicarboxylate rings and Pb2+ ions. The use of flexible luminescent Zn-coordination polymers as sensors for selective and direct detection of Pb2+ in aqueous media has been unexplored until now.

A highly efficient luminescent MOF-based TNP sensor fabricated by new AIE ligand

Designing and synthesizing functional metal–organic frameworks (MOFs) remains great challenges. In this study, a new aggregation-induced-emission (AIE) molecule 4,4′-(((9H-fluoren-9-ylidene)methylene)bis(4,1-phenylene))dipyridine (L) was developed as functional ligand to construct a unique MOF [Cu(I)2Cu(II)L2(SCN)4]n (1) with mixed-valence Cu centers. 1 is fabricated by 4-connected Cu(II) and Cu(I) building units, and “V” shaped L and linear SCN− bridges, and forms a three-dimensional (3-D) binodal (4, 4)-connected framework with rare non-interpenetrated (64·82)(66)2 network. 1 demonstrates excellent water, pH and thermal stabilities, and can efficiently detect TNP in aqueous medium. Its quenching constant and detection limit for sensing TNP reach 2.16 × 105 M−1 and 1.05 × 10−5 mM, respectively, which are better than those of the most MOF-based TNP sensors. Moreover, 1 exhibits notable TNP sensing selectivity and recyclability. The luminescence quenching sensing mechanism of 1 toward TNP is in-depth investigated.

Highly Sensitive Fluorescent Sensing for Nitrobenzene of CdII Complexes Based on Three Isomers and a Bis-Imidazole Ligand.

Detection of nitro pollutants is an important topic in environmental protection. A total of 3 Cd (II) complexes (1-3) based on 3 soft organic isomers, n-(3,5-dicarboxylato benzyloxy) benzoic acid (n = 2, 3 or 4-H3DBB), and a linear N-donor ligand, 3-bis(imidazole-l-ylmethyl) benzene (3-bibz), have been synthesized hydrothermally. Structural diversity of Complexes 1-3 displays the architectural 2D or 3D change: Complex 1 exhibits a 2D network featuring tri-nuclear metal units, Complex 2 is a 3D framework based on similar tri-nuclear metal units, and Complex 3 shows a 3D network with binuclear units. Fluorescent sensing properties exhibited in all these complexes have been discovered to detect nitrobenzene (NB) selectively and sensitively. In particular, Complex 3 possesses high sensitivity for NB with the lowest detection limit of 1.15 × 10-10 M. The results of the theoretical calculation verified the fluorescence detection mechanism of NB by these Cd-based complexes. Therefore, these Cd-based complexes might be used as excellent luminescent sensors for NB.

A Zn-MOF-based mixed matrix membrane as an ultrastable luminescent sensor for selective and visual detection of antibiotics and pesticides in food samples

The detection of antibiotics and pesticides are of great significance since their residues threaten the health of human beings by accumulation. However, most traditional solid chemical sensors are suffer from the limitations of low sensitivity and economic practicability because of the aggregating nature and unstable of solid sensors. Herein, a new luminescent sensor 1@PMMA (1, [(ZnL)·H2O]n (H2L = 5-(4-(pyridin-4-yl)benzamido)benzene-1,3-dioic acid); PMMA = poly(methyl methacrylate)) was successfully prepared. Notably, the polymer matrix provided the chemical protection for MOF particles. The as fabricated 1@PMMA was stable in milk, honey and egg as well as exhibited strong blue emission under ultraviolet light irradiation, which can act as luminescent probe for detecting antibiotics and pesticides. More interestingly, 1@PMMA exhibited visual, real-time and recyclable detection of antibiotics ornidazole (ODZ) and pesticides 2,6-dichloro-4-nitrobenzenamine (DCN) in real food samples. This work shows that the luminescent MOF-based mixed matrix membranes could be applied as good candidates for sensing analytes in practical application.

Chiral Linker Installation in a Metal-Organic Framework for Enantioselective Luminescent Sensing.

Linker installation is a potent strategy for integrating specific properties and functionalities into metal-organic frameworks (MOFs). This method enhances the structural diversity of frameworks and enables the precise construction of robust structures, complementing the conventional postsynthetic modification approaches, by fully leveraging open metal sites and active organic linkers at targeting locations. Herein, we demonstrated an insertion of a d-camphorate linker into a flexible Zr-based MOF, PCN-700, through linker installation. The resultant homochiral MOF not only exhibits remarkable stability but also functions as a highly efficient luminescent material for enantioselective sensing. Competitive absorption and energy/electron transfer processes contribute to the sensing performance, while the difference in binding affinities dominates the enantioselectivity. This work presents a straightforward route to crafting stable homochiral MOFs for enantioselective sensing.

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.