Terbium Metal-organic Framework Research Articles

Synthesis and fluorescence property of a new Tb-based metal-organic framework

A new 3D Terbium (III) metal-organic framework has been solvothermally synthesized by using terbium ion as the metal center and 1,1[Formula: see text],1[Formula: see text]-(2,4,6-trimethylphenyl-1,3,5-tri) trimethyl tritrium (4-carboxylpyridyl) tribromide (H3LBr3) as ligand. The molecular formula is [Tb(H3LBr3) (OH)2](NO3)●(DMAC)3. Compound crystallizes in the triclinic system, space group [Formula: see text], with [Formula: see text], [Formula: see text], [Formula: see text][Formula: see text]Å, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text][Formula: see text]Å3, [Formula: see text], [Formula: see text], [Formula: see text][Formula: see text]g/cm3, [Formula: see text][Formula: see text]mm[Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] for 7586 observed reflections ([Formula: see text] (I)). Meanwhile, the fluorescence property was also studied. The result shows that the synthesized Tb-MOF displays highly selective sensing of acetone.

A highly stable terbium metal−organic framework as a fluorescence turn-off sensor for glutamic acid in human urine and serum

Glutamic acid (Glu) is a biomarker of some neuropathological diseases, whose detection is of significance in early medical diagnosis. A 3D terbium metal-organic framework (Tb-ddb) is constructed from 1,3-di(3′,5′-dicarboxylphenyl)benzene (H4ddb) with Tb3+, displaying the 5D4 → 7Fj (j = 6-3) transfers of Tb(Ⅲ) at 490, 543, 584, and 621 nm. Tb-ddb has a high stability in water or common organic solvents. The sensitivity test shows a linear fitting equation of I0/I = 0.00443·CGlu + 0.93563 with LOD = 1.40 μM at CGlu = 0–500 μM. The detection performance of Tb-ddb is not affected by seven interferents of amino acids. High durability is supported by the stable emission intensities at 543 nm of blank Tb-ddb and Tb-ddb/Glu suspensions in five fluorescence quenching-recovery cycles. The returned CGlu close to the set CGlu and the recoveries around 100% demonstrate Tb-ddb sensing Glu in human urine and serum is reliable. The linear relationship between green value of the Tb-ddb strip and CGlu can realize the on-site Glu detection. Tb-ddb can be regarded as a promising fluorescence turn-off sensor to Glu with high sensitivity, selectivity and durability.

Rapid analysis of dichlorvos via releasing the phosphate core

Monitoring the residual dichlorvos (O,O-dimethyl-O-2,2-dichlorovinylphosphate, DDVP) in food has received extensive attention owing to its large consumption in agriculture. However, the previous sensing methods are not time-efficient enough due to the long incubation time for enzyme inhibition (tens of minutes to hours) or bottlenecked by the complicated procedures for senor fabrication. Herein, a novel sensing strategy is proposed based on the hydrolysis of DDVP into PO43−. By using alkaline phosphatase for hydrolysis, a certain portion of DDVP was transformed to PO43− within only 8 min. Then, the released PO43− was detected by a fluorescent terbium metal-organic framework (Tb-MOF). The coordination of the naked P–O groups to the metal nodes of the Tb-MOF disturbed the antenna effects of its ligands. Thus, DDVP was quantified by the decrease of the fluorescence of Tb ions. Based on this method, DDVP residues on plum surfaces were collected by swabs and successfully detected. The recovery of DDVP was determined in the range from 105 % to 115 %, demonstrating the quantification accuracy of this method. The detection limit reached 4.7 μM, which was lower than the restricted amount in fruit set by the National Standard of China. The present method provides an efficient and user-friendly way for the detection of DDVP and many other organophosphorus pesticides in food.

A new SERS quantitative analysis method for trace malathion with recognition and catalytic amplification difunctional MOFTb@Au@MIP nanoprobe

New multifunctional nanomaterial preparation and its application to trace pollutant analysis are interesting to peoples. Using terbium metal-organic framework loaded gold nanoparticles (MOFTb@Au) as the nanosubstrate and 3-aminopropyltriethoxysilane (APTES) as the functional monomer, a new bifunctional nanosurface molecularly imprinted polymer nanoprobe of MOFTb@Au@MIP with strongly recognition and catalytic amplification functions was prepared by the microwave sol-gel procedure. It was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier infrared spectroscopy (FTIR) and other techniques. The nanoprobe was found to specifically recognize malathion (MAL) and catalyze the L-cysteine (Cys)-HAuCl4 nanogold indicator reaction to amplify the molecular spectral signal. The gold nanoparticles (AuNPs) generated in the system show a strong surface-enhanced Raman scattering (SERS) effect, resonant Rayleigh scattering (RRS) peak and UV absorption (Abs) peak at 1615 cm−1, 370 nm and 520 nm, respectively. Based on this, a new SERS/RRS/Abs trimode method for the detection of MAL can be established. It has been applied to the analysis of cereal samples with satisfactory recoveries of 95.2–107.4% and precision of 3.76–9.06%.

High-efficiency detection of phenylamine biomarker based on a stable terbium metal-organic framework

Phenylamine was listed as a carcinogen. Nevertheless, the detection of phenylamine in humans is complicated and challenging. In this work, a stable Tb-MOF {[Tb(L)(NMP)2]·2NMP}n (1-Tb) was synthesized by solvothermal method based on 3,5-bis((3′-carboxyphenyl)oxy)-benzoic acid (H3L) and Tb(III) ion. 1-Tb possesses the ability to quantitatively detect p-aminophenol (PAP) in human urine, and its limit of detection (LOD) is 8.69 × 10−4 ppm, which is lower than most reported MOFs. Furthermore, the fluorescence quenching mechanism is dynamic quenching and FRET (fluorescence resonance energy transfer) via experiments and theoretical computations in depth. 1-Tb exhibits excellent selectivity, high sensitivity, and outstanding stability. Hence, 1-Tb is anticipated to be a potential candidate material for a fluorescence sensor in the biological field.

TbMOF@Au catalytic determination of trace malathion with aptamer SERS/RRS/Abs assay.

Terbium metal-organic framework (TbMOF) was prepared by microwave method with 1,3,5-benzenetricarboxylic acid as ligand. With HAuCl4 as precursor and NaBH4 as reducing agent, TbMOF-loaded gold nanoparticles (AuNPs) catalyst (TbMOF@Au1) was prepared rapidly and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was found that TbMOF@Au1 has a strong catalytic effect on the HAuCl4-Cys nanoreaction, and the produced AuNPs have a strong resonant Rayleigh scattering (RRS) peak and surface plasmon resonance absorption (Abs) peak at 370nm and 550nm, respectively. With the addition of the molecular probe Victoria blue 4R (VB4r), AuNPs have a strong surface-enhanced Raman scattering (SERS) effect, the target analyte molecules are trapped in between the nanoparticles and a hot spot effect created in the process resulting in an extremely high SERS signal. A new SERS/RRS/Abs triple-mode analysis method for Malathion (MAL) was established by coupling this new TbMOF@Au1 catalytic indicator reaction with MAL aptamer (Apt) reaction, and its SERS detection limit was 0.21ng/mL. The SERS quantitative analysis method has been applied to the analysis of fruit samples with the recovery of 92.6-106.6% and the precision of 2.72-8.16%.

A water-stable Tb-MOF as a multifunctional luminescent sensor for Fe3+ and Cr2O72− in water

A 3D terbium metal–organic framework, {[Tb(CPBi)(DMF)(H2O)]·H2O}n. (namely Tb-MOF, H3CPBi = 2-(3,5-dicarboxyphenyl)-6-carboxybenzimidazole, DMF = N,N-Dimethylformamide) was synthesized under solvothermal conditions for the luminescent study. By virtue of the strong luminescence and excellent water stability, Tb-MOF has been applied as a multi-responsive luminescent sensor for Fe3+ and Cr2O72− in aqueous solutions, which exhibits outstanding detection effect with high selectivity and sensitivity. The Ksv values of Tb-MOF for Fe3+ and Cr2O72− are 7.435 × 103 M−1 and 1.1652 × 104 M−1 in water systems, respectively. Meanwhile, the possible detecting mechanisms of Tb-MOF for Fe3+ and Cr2O72− were further speculated.

Dual-functional lanthanide-MOF probe nanocomposite based on hydroxyapatite nanowires as fluorescent sensor for ascorbic acid.

Adual-functional lanthanide-MOF nanocomposite probewas designed and constructed for the detection of ascorbic acid (AA). The magnetically functionalized hydroxyapatite nanowires are selected as the carriers and simultaneously loaded with ciprofloxacin (CIP) and terbium metal organic framework to form the internal reference fluorescence probe nanocomposite (Fe3O4-HAPNWs-Tb/MOF-CIP). This dual-functional lanthanide-MOF probe not only combines the respectively unique fluorescence properties of lanthanide MOFs and CIP, but also takes full advantage of the rapid separation properties of the magnetic component. Structural and spectroscopic characterization results have demonstrated the successful synthesis of probe material and the fluorescence mechanism. At a suitable excitation wavelength (295nm), the probe can simultaneously emit characteristic fluorescence of CIP (445nm) and Tb3+ (543nm). In the presence of AA, the ratio of I543/I445 decreases rapidly with increasing of AA concentration. The linear range of determinationis 0.3-40μM with a detection limit of 20.4nM. Thecontents of AA in vitamin C tablets and four fruit juice samples were detected by the composite probe. The spiked recoveries ranged from 82.6 to 104.2% with relative standard deviations (RSD) less than 2.1%, revealing the practical application value of the developed sensor in healthcare and food fields. A novel internal reference fluorescence sensor (Fe O -HAPNWs-Tb/MOF-CIP) was constructed for detecting ascorbic acid by solvothermal and self-assembly techniques, showing excellent selectivity and sensitivity based on the different responses of Tb/MOF and CIP to the target.

Terbium metal organic framework hollow spheres: Sensing properties for trace water in organic solvents and iron ions in water

Terbium metal organic frameworks (Tb-MOFs) hollow spheres were synthesized by solvothermal method, using 5-aminoisophthalic acid (H2AIP) as organic ligand, 2-methylimidazole (2-MI) as competitive ligand and protective agent. Tb-MOFs exhibit excellent luminescent sensing properties to water in organic solvents, and the limit of detections (LODs) in N, N-dimethylformamide and ethanol are 0.000515% and 0.000422%, respectively. Water can not only enhance the luminescent properties of Tb-MOFs, and also a new emission peak at 418 nm (or 427 nm) appears. The enhancement and new peak are quenched by the Fe3+ in water, and the LODs of Tb-MOFs for Fe3+ at 402 nm and 545 nm are 0.45 μM and 0.71 μM, respectively. The sensing mechanism for water is water can replace part of the coordination of H2AIP with Tb3+, and the sensing mechanism for Fe3+ is that the competitive absorption between Fe3+ and H2AIP inhibits the energy absorption of the organic ligand.

Expanding the Knowledge of the Selective-Sensing Mechanism of Nitro Compounds by Luminescent Terbium Metal-Organic Frameworks through Multiconfigurational ab Initio Calculations.

The current research shows that the excited-state dynamics of the antenna ligand, both in the interacting system sensor/analyte and in the sensor without analyte, is a safe tool for elucidating the detection principle of the luminescent lanthanide-based metal-organic framework sensors. In this report the detection principle of the luminescence quenching mechanism in two Tb-based MOFs sensors is elucidated. The first system is a luminescent Tb-MOF [Tb(BTTA)1.5(H2O)4.5]n (H2BTTA = 2,5-bis(1H-1,2,4-triazol-1-yl) terephthalic acid) selective to nitrobenzene (NB), labeled as Tb-1. The second system is {[Tb(DPYT)(BPDC)1/2(NO3)]·H2O}n (DPYT = 2,5-di(pyridin-4-yl) terephthalic acid, BPDC = biphenyl-4,4'-dicarboxylic acid), reported as a selective chemical sensor to nitromethane (NM) in situ, labeled as Tb-2. The luminescence quenching of the MOFs is promoted by intermolecular interactions with the analytes that induce destabilization of the T1 electronic state of the linker "antenna", altering thus the sensitization pathways of the Tb atoms. This study demonstrates the value of host-guest interaction simulations and the rate constants of the radiative and nonradiative processes in understanding and elucidating the sensing mechanism in Ln-MOF sensors.

Transformation of Amorphous Terbium Metal-Organic Framework on Terbium Oxide TbOx(111) Thin Film on Pt(111) Substrate: Structure of TbxOy Film.

The present study is focused on the synthesis and structural properties of amorphous terbium metal–organic framework thin film (TbMOF-TF) and its transformation to terbium oxide by pyrolysis at 450 °C in the air. The crystalline (cTbMOF) and amorphous (aTbMOF) films were prepared by solvothermal synthesis using different amounts (0.4 and 0.7 mmol) of the modulator (sodium acetate), respectively. The powders were characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), Fourier transform infrared (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM). The varied chemical composition of the surface of TbMOFs and TbxOy was investigated by X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that aTbMOF had been fully transformed to a Tb4O7 phase with a cubic crystal structure at 450 °C. The amorphous aTbMOF-TF film was prepared by dropping a colloidal solution of amorphous precursor nanocrystals on the SiO2/Si substrates covered with Pt as an interlayer. XPS confirmed the presence of Tb in two states, Tb3+ and Tb4+. The amorphous film has a rough, porous microstructure and is composed of large clusters of worm-like particles, while terbium oxide film consists of fine crystallites of cubic fluorite cF-TbOx, c-Tb4O7, and c-Tb2O3 phases. The surface topography was investigated by a combination of confocal (CM) and atomic force microscopy (AFM). The amorphous film is porous and rough, which is contrast to the crystalline terbium oxide film.

A highly stable terbium(III) metal-organic framework MOF-76(Tb) for hydrogen storage and humidity sensing.

The present study described the synthesis and characterization of MOF-76(Tb) for hydrogen storage and humidity sensing applications. The structure and morphology of as-synthesized material were studied using powder X-ray diffraction, scanning, and transmission electron microscopy. The crystal structure of MOF-76(Tb) consists of terbium(III) and benzene-1,3,5-tricarboxylate(-III) ions, one coordinated aqua ligand and one crystallization N,N´-dimethylformamide molecule. The polymeric framework of MOF-76(Tb) contains 1D sinusoidally shaped channels with sizes of 6.6 × 6.6 Å propagating along c crystallographic axis. The thermogravimetric analysis of the prepared material exhibited thermal stability up to 600 °C. At 77 K and pressure up to 20 bar; 0.6 wt.% hydrogen storage capacity for MOF-76(Tb) was observed. Finally, the humidity sensing measurements (water adsorption experiments) were performed, and the results indicate that MOF-76(Tb) is not a suitable material for moisture sensing applications.

Metal-organic frameworks of rare earth metals embedded side-by-side nanofiber as a switchable luminescent sensor for Fe3+ and Cu2+ in aqueous media

Europium metal-organic frameworks (Eu-MOFs) and terbium metal-organic frameworks (Tb-MOFs) incorporated side-by-side nanofibrous membrane (Eu//Tb SBS NFs) was successfully fabricated by electrospinning. Eu-MOFs or Tb-MOFs emitting red or green light, respectively, were adjusted on each side, and a luminescent sensor with yellow luminescence was prepared by adjusting the ratio of the two MOFs. Eu//Tb SBS NFs have high luminescence efficiency and show sequential changes in luminescence color (yellow-green-gray). To investigate whether it is possible to detect metal ions reliably in aqueous media, we evaluated the wettability of the samples by contact angle measurement and luminescence stability in different pH conditions. Eu//Tb SBS NFs showed selective detection of Fe3+ and Cu2+ in aqueous solutions containing various metal ions. The quenching effect constant (Ksv) for Fe3+ was calculated as 7.62 x 103 M−1 (the limit of detection = 1.6 x 10−7 M), indicating high sensitivity for Fe3+. The luminescence changes of the Eu//Tb SBS NFs resulting from the presence of the metal ions and varying concentrations of the targeted metal ions were confirmed with the naked eye. This is the first report of a nanofibrous membrane with a unique side-by-side structure designed as a luminescence switchable dual sensor for Fe3+ and Cu2+. The superiority of Eu//Tb SBS NFs as luminescent sensors is discussed in this paper.

A smart nanoprobe based on luminescent terbium metal–organic framework coated gold nanorods for monitoring and photo-stimulated combined thermal-chemotherapy

Real-time monitoring and accurate treatment are of great significance for reducing the side effects during the cancer therapy. In this work, we rationally prepared a smart nanoprobe based on core–shell terbium metal–organic gramework (MOF) with highly effective photothermal conversion capacity and drug release efficiency under near-infrared light irradiation for real-time fluorescence imaging-guided multimodal therapy. The nanoprobe can achieve prominent photothermal therapy and controllable drug release, act as a fluorescence thermometer, and also real-time feedback of temperature is expected to be achieved. At the same time, the two-photon ligand design significantly improves the tissue penetration ability of the nanoprobe. Our work is expected to provide a reference for precise treatment and real-time monitoring of tumors and at the same time provide new ideas for the formulation of individualized treatment plans.

Stable terbium metal-organic framework with turn-on and blue-shift fluorescence sensing for acidic amino acids (L-aspartate and L-glutamine) and cations (Al3+ and Ga3+).

A terbium-based metal-organic framework, namely {[Tb2(ADIP)(H2ADIP)(HCOOH)(H2O)2]·2DMF·2H2O}n (Tb-MOF, H4ADIP = 5,5'-(anthracene-9,10-diyl) diisophthalic acid), was synthesized and characterized. The single-crystal structure analysis shows that the Tb-MOF crystallizes in the C2/C space group in the monoclinic system and its asymmetric unit contains two TbIII ions, one ADIP4-, one H2ADIP2-, one coordinating formic acid and two coordination water molecules. Tb-MOF has a three-dimensional porous structure with a porosity of 41.5%. Tb-MOF is a highly selective and sensitive fluorescence turn-on and blue-shift sensor for L-aspartate (Asp), L-glutamine (Glu), Al3+ and Ga3+with detection limits of 0.25, 0.23, 0.069 and 0.079 μM, respectively. Experimental studies and theoretical calculations show that the sensing process is mainly attributed to the energy transfer and the absorbance caused enhancement (ACE) mechanism. Therefore, Tb-MOF is a good multi-response fluorescence sensor for acidic amino acids and Al3+, Ga3+cations.

Terbium metal-organic framework/bovine serum albumin capped gold nanoclusters-based dual-emission reverse change ratio fluorescence nanoplatform for fluorimetric and colorimetric sensing of heparin and chondroitin sulfate

In this work, we designed a novel dual-emission reverse change ratio fluorescence nanoplatform for fluorimetric and colorimetric sensing of heparin (Hep) and chondroitin sulfate (CS) based on green emissive terbium metal-organic framework (Tb MOF) and red emissive bovine serum albumin capped gold nanoclusters (BSA@AuNCs). When excess Tb MOF was mixed with BSA@Au NCs, the nanoaggregates of Tb MOF and BSA@Au NCs could be precipitated by centrifugation due to the electrostatic interactions between them, and the supernatant displayed bright green color of Tb MOF under 254 nm UV lamp. However, the introduced Hep or CS caused the decomposition of Tb MOF since Tb3+ has stronger affinity with Hep and CS, which resulted in the release of BSA@AuNCs into the supernatant. As a result, the red fluorescence of BSA@Au NCs turned on while the green fluorescence of Tb MOF turned off under the 254 nm UV illumination. The dual- emission reverse change ratio fluorescence nanoplatform possessed the variations of the emission intensity ratio at two different wavelength and the corresponding green-to-red fluorescent color changes, endowing a novel mechanism for fluorimetric and colorimetric analysis of Hep and CS using fluorescence spectrophotometer and smartphone, respectively. With the ratiometric fluorescence nanoprobe, simple and rapid sensing of Hep and CS with high sensitivity, selectivity and accuracy could be realized. Moreover, successful recoveries of the analytes in human serum samples were also validated, indicating promising application for Hep and CS analysis in biomedical diagnosis.

A Terbium Metal–Organic Framework Platform for Determination of Lamotrigine in Exhaled Breath Condensate

Background: Lamotrigine is widely used in the management of partial epilepsy, generalized tonic-clonic epilepsy and Lenox-Gastut syndrome and an add-on therapy in the treatment of complex and simple partial seizures and secondarily generalized tonic-clonic seizures resistant to multiple drug therapy. Methods: In the current study, a fluorometric nanoprobe based on metal–organic frameworks (MOF) was designed for the determination of lamotrigine in exhaled breath condensate (EBC). The MOF nanoprobe consisted of Tb3+ ions as metal part and dimethylformamide (DMF) and 1,10-phenanthroline (Phen) as organic parts of nanoprobe. Results: The used probe shows a week fluorescence in alkaline media owing to an energy transfer from nitrogen groups of DMF and Phen on carbonyl group of DMF as an antenna for Tb3+ luminescence. However, its fluorescence is enhanced in acidic conditions by protonation of DMF nitrogen atoms and Phen and deactivation of energy transfer pathways of nitrogen groups to carbonyl group. Lamotrigine addition to this fluorescent system leads to quenching in the fluorescence intensity due to reactivation of the above mentioned energy transfer pathways resulting in competitive interaction with H+ ions. Moreover, the inner filter effect (IFE) of lamotrigine on DMF–Tb–Phen MOF NPs is considered as another reason for the observed quenching in the fluorescence of DMF–Tb–Phen MOF NPs. The intensity of the fluorescence was recorded at λem = 545 nm and the difference between fluorescence signal in the absence and presence of lamotrigine was the analytical response. The factors affected on experimental conditions were optimized utilizing a multivariate optimization technique. The validation of nanoprobe response to lamotrigine gives a linear relationship in the range of 0.05 to 2.0 µg⋅mL‒1 with a detection limit of 11.0 ng⋅mL‒1 for lamotrigine. Conclusion: The developed method reveals good repeatability and selectivity for lamotrigine in real samples.

Copper doped terbium metal organic framework as emitter for sensitive electrochemiluminescence detection of CYFRA 21-1

Lanthanide metal organic frameworks (L-MOFs) are emerging as promising electrochemiluminescence (ECL) emitters for bioanalysis. This work proposed a copper doped terbium MOF as a luminescent tag for construction of a “signal-on” ECL immunosensing method. The Tb–Cu-PA MOF was prepared using Tb3+ and Cu2+ ions as metal linkers and m-phthalic acid as bridge ligand, and exhibited strong ECL emission with K2S2O8 as a coreactant. The immunosensor was prepared by immobilizing capture antibody on Pd nanoparticles modified Ni–Co layered double hydroxide (Pd-ZIF-67@LDH) nanoboxes, which showed strong electrocatalytic activity toward the reduction of S2O82− for amplifying the ECL signal. Upon the sandwich-typed immunoreactions, Tb–Cu-PA MOF labeled antibody was introduced onto the immunosensor for sensitive ECL detection of target protein. Using cytokeratin 19 fragment 21–1 (CYFRA21-1), a representative lung cancer biomarker, as target model, the ECL immunosensing method showed a linear range of 0.01–100 ng/mL and a detection limit of 2.6 pg/mL (S/N = 3). This immunosensing strategy highlighted the advances of using luminescent and electroactive MOFs in the developments of highly efficient immunosensors for bioanalysis.

A highly sensitive and multi-responsive Tb-MOF fluorescent sensor for the detection of Pb2+, Cr2O72−, B4O72−, aniline, nitrobenzene and cefixime

A terbium metal organic framework (Tb-MOF), namely {[Tb(dppa)(H2O)2]·dima·H2O·0.5O}n (1), (H4dppa = 5-(3′4′-dicarboxylphenoxy)isophthalic acid, dima = dimethylamine, which is formed by the decomposition of DMF in aqueous solution at high temperature.) was prepared and characterized. Tb-MOF is connected by (dppa)4- ligands via μ4:η1,η2,η2,η2 coordination mode to form a two-dimensional wavy network, which is extended to three-dimensional supramolecular structures based on hydrogen bonding. Tb-MOF has excellent fluorescence properties, which can be used for fluorescence recognition and quantitative determination of cation and anion, antibiotics and small organic molecules in aqueous solution with high sensitivity and good selectivity. Tb-MOF showed enhanced fluorescene for Pb2+ and B4O72− ions, while quenching fluorescence for Cr2O72− ion. Noticeably, this is the first time that Pb2+ and B4O72− ions have been detected by a MOF-based fluorescence sensor using a fluorescence enhancement mechanism. More interestingly, Tb-MOF can quantitatively detect aniline (ANI) in aqueous solution by ratiometric fluorescence sensing. In addition, Tb-MOF has great selectivity and sensitivity for detecting of nitrobenzene (NB) and cefixime (CEF). In particular, when NB concentration is 50 μM, the fluorescence quenching rate of Tb-MOF reaches 99.6%. Therefore, this paper introduces a highly sensitive and multi-responsive Tb-MOF sensor, which can be used to detect Pb2+, B4O72−, Cr2O72−, ANI, NB and CEF with fast response speed and good selectivity.

A recycled Tb-MOF fluorescent sensing material for highly sensitive and selective detection of tetracycline in milk

A novel three-dimensional terbium metal–organic framework (Tb-MOF) sensing material has been synthesized by hydrothermal method and applied in fluorescent detection of tetracycline (TC) in milk. The sensing material could emit strong green fluorescence with a long fluorescence lifetime (906.48 ± 1.49 μs), which could be sensitively and selectively quenched by TC aqueous solution. Meanwhile, it had the characteristics of fast response (2 min), low detection limit (184 nmol/L), wide linear range (0–100 and 100–244 μmol/L) and recyclable luminescence sensing during TC detection. The luminescence quenching mechanism was mainly derived from the inner-filter effect and energy transfer from ligand to Tb3+ ion. Furthermore, satisfactory recoveries of 93.5–104.2% were obtained in TC spiked raw milk and pasteurized milk samples, suggesting the potential application of Tb-MOF in the detection of TC in food engineering.