Emission Of Tb3 Research Articles

[formula omitted] leaves mediated combustion synthesis of Tb[formula omitted] doped Zn2V2O7 nanoparticles: Color tunable photoluminescence and electrochemical studies for display and supercapacitor applications

A new series of Tb3+ doped Zn2V2O7 (ZV) nanoparticles (NPs) at different concentration from 1 to 9 mol% was synthesized by Menthaspicata leaves extract mediated solution combustion method. On Tb3+ doping, the diffraction pattern matches well with the monoclinic crystal structure with the C2/c(2/m) space group of ZV host matrix. The surface morphology tuned from irregular shaped NPs to hexagonal shaped NPs with variation in dopant concentration. The crystallite size estimated from Scherrer’s method matches well with the transmission electron microscopy analysis. The optical band gap determined from Tauc’s plot utilizing UV–Visible absorption was tuned from 3.061 to 3.035 eV with increase in dopant concentration. Under 266 nm excitation, the emission of Tb3+ ions from Tb3+-doped ZV NPs is observed, with the intensity of emission showing sensitivity to the concentration of Tb3+ ions. The optimal doping content is determined to be 7 mol %. The CIE coordinates clearly indicates the tuning of the emission color from green to blue region with increase in dopant concentration. The average color coordinated temperature was found to be 7895 K showing the cooler appearance. Further, cyclic voltammetry analysis offers valuable insights into redox reactions, electrode kinetics, and overall electrochemical behavior, while Electrochemical Impedance Spectroscopy (EIS) provides information on ion transport kinetics. Galvanostatic Charge–Discharge (GCD) analysis revealed supercapacitance values ranging from 79.43 to 133.26 F/g at 10 mV/s with increasing dopant concentration. These findings underscore the potential of this material for use in energy storage and display technology applications.

Synthesis, characterization, and temperature-dependent luminescence of Tb3+-activated and self-activated Sr10(PO4)6Cl2 phosphors

In this work, a series of new nanosized phosphors based on strontium chlorapatite (Sr10(PO4)6Cl2, abbreviated as SrClAp) with varying terbium concentration were synthesized using a modified microwave-hydrothermal method. This study meticulously investigated the impact of Tb3+ concentration and annealing temperature on factors such as crystal purity, particle morphology, photoluminescence, chromatic properties, and the mechanism of thermal quenching.The synthesized phosphors underwent characterization using X-Ray Diffraction (XRD) and scanning electron microscopy (SEM) to verify their crystal structure purity and examine their morphology. Upon near-ultraviolet (NUV) excitation at the 378 nm line, the obtained nanosized powders emitted green light arising from the characteristic 5D4→7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. Notably, a broad host-related emission was discernible at 80 K, with its intensity diminishing as the temperature increased. The mechanism governing this host-related emission and the process of its thermal quenching have been proposed. Moreover, a comprehensive exploration of the influence of ambient temperature on the emission of Tb3+-doped SrClAp was undertaken.

Fabrication of Tb/Eu co-doped borosilicate glasses for white-light LED and broadband photodetection

We successfully prepared a series of rare-earth doped borosilicate glasses using the melt-quenching method, and carefully investigated the luminescent properties and the spectral modulation of Tb/Eu-cdoped borosilicate glasses under UV (200–400 nm) excitation. The results show that the prepared samples have the characteristics of broadband response, excellent transparency and tunable luminescence. By adjusting the excitation wavelength, the emissions of Tb3+, Eu2+ and Eu3+ ions are observed, which exhibit yellow-green, blue, red color and multi-color even white emissions, respectively. Moreover, the energy transfer between Tb3+ and Eu3+ ions in the codoped glasses is confirmed. Tb3+ absorbs a large number of solar-blind light, transfers to Eu3+ and results in intense visible emission in a wide waveband range. This makes the Tb/Eu codoped glass a desirable candidate for solar-blind light detections. The photodetection system was built and shows a strong and stable response to the UV light of 210–400 nm. Due to broad detection range, high sensitivity and stability, our results offer strong implications for the development of photodetection device for diverse applications.

Optical temperature sensing properties realized by isotropic negative thermal expansion in ScF3:Tb3+/Eu3+ phosphor ceramics

The anomalous luminescence thermal quenching performance caused by negative thermal expansion has attracted much attention due to the potential application in optical fields. However, the downshifting emissions with abnormal thermal quenching achieved by isotropic negative thermal expansion for optical temperature sensing applications are still lacking. Herein, a large enhancement of red emission and a high temperature sensing performance are realized by isotropic negative thermal expansion in ScF3:Tb3+/Eu3+ phosphors ceramics. Specially, a selectively thermal enhanced red emission of Eu3+ from 5D0→7F2 with hypersensitive transition characteristics could be obtained due to the thermal stimulated lattice distortion. Attributing to the shortening of cation spacing, the energy transfer efficiency between Tb3+ and Eu3+ is largely enhanced with the increasing of the temperature from 303 to 473 K. The enhanced energy transfer leads to that the emission of Tb3+ firstly increases and then slightly decreases, whereas the emission from Eu3+ has been largely improved. Finally, an optical temperature sensing strategy based on the fluorescence intensity ratio of the sensitizer Tb3+ (signal ions) and the activator Eu3+ (referring ions) is designed, attributing to the distinguishable luminescence response to the temperature. The obtained maximum relative sensitivity is 1.04 % K−1 (@303 K). Besides, the sensing strategy based on lifetime mode also suggests a maximum relative sensitivity of 1.00 % K−1 at 343 K. It provides a feasible strategy to obtain an optical temperature sensing material with high emission efficiency at a high temperature, which sheds light on the design of luminescence materials keeping high luminescence stability in a wide temperature range in the fields of optical temperature sensing.

Ratiometric emission of Tb(III)-functionalized Cd-based layered MOFs for portable visual detection of trace amounts of diquat in apples, potatoes and corn

Diquat (DQ) is a typical bipyridine herbicide widely used to control weeds in fields and orchards. The severe toxicity of diquat poses a serious threat to the environment and human health. Metal-organic frameworks (MOFs) have received widespread attention due to their unique physical and chemical properties and applications in the detection of toxic and harmful substances. In this work, a two-dimensional (2D) Tb(III) functionalized MOF Tb(III)@1 (1 = [Cd(HTATB)(bimb)]n·H2O (Cd-MOF), H3TATB = 4,4′,4″-triazine-2,4,6-tribenzoicacid, bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene) has been prepared and characterized. Tb(III)@1 has excellent optical properties and high water and chemical stability. After the Tb(III) is fixed by the uncoordinated -COO- in the 1 framework, Tb(III)@1 emits the typical green fluorescence of the lanthanide ion Tb(III) through the “antenna effect”. It is worth noting that Tb(III)@1 can be used as a dual emission fluorescence chemical sensor for the ratio fluorescence detection of pesticide DQ, exhibiting a relatively low detection limit of 0.06 nM and a wide detection range of 0–50 nM. After the addition of DQ, a rapid color change of Tb(III)@1 fluorescence from green to blue was observed due to the combined effects of IFE, FRET and dynamic quenching. Therefore, a simple test paper box has been designed for direct on-site determination of pesticide DQ. In addition, the developed sensor has been successfully applied to the detection of DQ in real samples (fruits a Yin-Xia Sun and Bo-Tao Ji contributed equally to this work and should be considered co-first authors.nd vegetables) with satisfactory results. The results indicate that the probe developed in this study has broad application prospects in both real sample detection and actual on-site testing.

Structures, photoluminescence, and magnetism of 1D lanthanide coordination polymers dominated on 3,5‐dichlorobenzoate

AbstractTwo series of novel coordination polymers (CPs), namely, Ln3(3,5‐DCB)9(bipy) (H2O)2·(bipy) [Ln = Nd (1), Sm (2)] and Ln2(3,5‐DCB)6(bipy)H2O [Ln = Eu (3), Gd (4), Tb (5) and Dy (6)], have been synthesized by hydrothermal reaction of a bridging ligand, 3,5‐dichlorobenzoic acid (3,5‐HDCB), with LnCl3·nH2O and N‐donor neutral ligand, 2,2′‐bipyridine (bipy). Single‐crystal x‐ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), and powder x‐ray diffraction (PXRD) for 1–6 are presented. CPs 1 and 2 exhibit trinuclear lanthanide architectures, in which the center Ln(III) are seven‐coordinated and eight‐coordinated adopting monocapped triangular prismatic, distorted square antiprism and bicapped trigonal prismatic coordination geometry, respectively, whereas CPs 3–6 are isostructural dinuclear structures. The center Ln(III) ions are also seven‐coordinated and eight‐coordinated with different coordinate modes adopting distorted monocapped triangular prismatic and square antiprism coordination geometry. Trinuclear CPs 1 and 2 are packed together via hydrogen‐bonding interaction to form the two‐dimensional (2D) supramolecular layers. CPs 3–6 exhibit 2D layers by the π–π interaction. CPs 2, 3, 5, and 6 display the characteristic fluorescent emissions of Sm(III), Eu(III), Tb(III), and Dy(III), respectively. CPs 1 and 4–6 exhibit corresponding weak anti‐ferromagnetic and ferromagnetic interactions of Nd(III), Gd(III), Tb(III), and Dy(III) in the low‐temperature range.

Effective photosensitized emission of a Tb(III) complex using a β-diketonate photosensitizer and an oxygen barrier system in a thermally populated triplet state.

Photosensitizer design of luminescent terbium (Tb(III)) complexes with narrow bandwidths is important for advancing luminescent materials. In this study, we report an effective photosensitizer model in a thermally populated lowest excited triplet (T1) state during Tb(III) emission. The Tb(III) complex comprises a Tb(III) ion (serving as an emission center), hexafluoroacetylacetonates (acting as photosensitizer ligands), and bulky cyclohexyl group-attached phosphine-oxide-type ligands (functioning as an oxygen barrier system). Emission properties including emission and excitation spectra, ligand-excited emission quantum yields, and emission lifetimes were evaluated in the absence and presence of oxygen. Coordination geometry structures were determined through analysing single-crystal structures. The electronic structure based on 4f-orbitals was estimated from radiative rate constants and quantum chemical calculations. The bulky phosphine oxide ligand not only provides an oxygen barrier system but also induces an electronic structural modulation based on 4f-orbitals, allowing for effective photosensitized Tb(III) emission in a thermally populated ligand T1 state in air.

Lead-free double perovskite Cs2NaInCl6 nanocrystals doped with Sb3+ and Tb3+ for copper ions detection in lubricating oil

Detecting heavy metal copper ions in lubricating oil holds immense significance for assessing mechanical wear and predicting mechanical failure. While perovskite nanocrystals offer high sensitivity in detecting copper ions, traditional lead halide perovskites suffer from lead toxicity defects. Lead-free perovskites, like Cs2NaInCl6, avoid the issue of lead toxicity but display lower luminescence intensity due to the presence of forbidden optical transitions. To address these issues, this study synthesized Cs2NaInCl6 nanocrystals (NCs) co-doped with Sb3+ and Tb3+ ions for copper ions detection in lubricating oil. The introduction of Sb3+ effectively reduced the band gap of the Cs2NaInCl6 host, creating an energy transfer pathway for Tb3+ emission via self-trapped excitations (STEs). Moreover, the doping of Tb3+ ions resulted in the suppression of STEs emission due to electron transfer from STEs to Tb3+. The emission of Tb3+ increased initially and then decreased with the increasing Tb3+ concentration, peaking at 40 %. Finally, Cs2NaInCl6: 2.5 %Sb3+, 40 %Tb3+ NCs were employed as probes for copper ions detection, exhibiting superior sensitivity and selectivity compared to similar probes. The presence of copper ions introduced competition between copper and Tb3+ for electrons from STEs, consequently leading to the quenching of multiple emission intensities associated with STEs and Tb3+. This method shows promising potential in predicting mechanical failure.

Bimetallic Eu/Tb Complexes for Ratiometric Temperature Sensing with Unusual Enhancement of Eu Luminescence with Temperature

In this paper we describe the results of the influence of temperature in the range of 280–340 K on the luminescence of bimetallic Eu/Tb complexes with N-heterocyclic ligand L based on 2,2′-bipyridyldicarboxylic acid in acetonitrile. The experiments were carried out for systems with various Eu/Tb ratios. The stability of the complexes of the ligand L with metal M (Eu or Tb) was determined using spectrophotometric titration in acetonitrile solutions. The LM complexes’ stability constants were found to be typical for these systems; however, the stability of Eu complex is slightly higher than that for Tb. Along with rising temperature, we observed a decrease in Tb emission intensity and, at the same time, an enhancement in Eu luminescence. An explanation of Eu luminescence enhancement involves the appearance of charge transfer states, bands of which can be observed in the Eu luminescence excitation spectra as difference spectra measured with two close temperatures. The unusual Eu luminescence enhancement upon heating was observed for the first time for the complex with tetradentate O,N-type heterocyclic diamide ligand L, while an inverse phenomenon was observed with the Tb luminescence. The Eu luminescence enhancement was found earlier for various carboxylate complex salts, but not for heterocyclic coordination complexes. This allows the construction of a ratiometric luminescent thermometer in the range of 280–340 K using the ratio of luminescence intensities for Eu and Tb. The stability constants for the individual Eu and Tb complexes help us to understand the equilibrium in L:Tb:Eu complex system and shed light on plausible speciation in solution.

Enhanced green emissions and excellent thermal stability of Ce3+-Tb3+ co-activated Na3.6Y1.8(PO4)3 phosphors via high efficiency energy transfer

In this paper, the authors synthesized Na3.6Y1.8(PO4)3: Ce3+, Na3.6Y1.8(PO4)3: Tb3+ and Na3.6Y1.8(PO4)3: Ce3+, Tb3+ phosphors (Na3.6Y1.8(PO4)3 abbreviated as NYPO) via a high-temperature solid-phase method and investigated the luminescent properties. NYPO:Ce3+ phosphor has a broad emission band peaking at 379 nm with an optimal doping concentration of Ce3+ being 6 mol%. It is shown that NYPO:Tb3+ phosphor has green emissions peaking at 540 nm with a quenching concentration of Tb3+ being 27 mol%. It is also found that the emissions of Tb3+ in Ce3+-Tb3+ co-activated NYPO phosphors can be enhanced and tuned effectively through an energy transfer (ET) between Ce3+ and Tb3+ with a transfer efficiency as high as 79 %. In addition, NYPO:Ce3+,Tb3+ phosphor shows excellent thermal stability with nearly 100 % retained luminescence even at 498 K, revealing that NYPO:Ce3+,Tb3+ has potential applications in phosphor-converted LEDs (Pc-LEDs).

Metal-Organic Framework Fluorescence Sensors for Rapid and Accurate Detection of Melamine in Milk Powder.

In this research, a simple, label-free, and ultra-sensitive fluorescent platform based on a metal-organic framework (MOF) has been developed to detect melamine in milk powder. This fluorescence sensor was fabricated from sensitized terbium (Tb)@NH2-MIL-253 (Al) MOF using a hydrothermal method that involved combining the green emission of Tb (λem = 545 nm) with the blue emission of NH2-MIL-253(Al) MOF (λem = 430 nm) under a single excitation wavelength (λex = 335 nm). The fluorescence sensor was then used under optimized conditions (pH = 9.0; sensor concentration = 30 mg/L; response time = 30 s) to quantify melamine in milk powder. The accuracy, sensitivity, and reproducibility of this sensor were established compared to the high-performance liquid chromatography (HPLC) method. The linear range and lower limit of detection (LLOD, computed with 3σ/S) of the sensor were between 40-396.45 nM (equal to 25 µg/kg-0.25 mg/kg) and 40 nM (equal to 25 µg/kg), respectively, which is much less than the maximum residual level (MRL) for the detection of melamine in infant formula (1 mg/kg) and other foods/feeds (2.5 mg/kg). Additionally, the results had good agreement with the HPLC outcomes, suggesting that the NH2-MIL-253(Al) MOF sensing probe has great precision and repeatability. To conclude, the new fluorescence sensor developed in this study can accurately and sensitively detect melamine in food samples, which may be useful for screening for adulteration of milk powders and other foods.

Formation of lanthanide luminescent di-metallic helicates in solution using a bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligand.

The chiral bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligand 1 was used in the formation of lanthanide di- and triple stranded di-metallic helicates in acetonitrile solution, where the changes in the ground and the Tb(III) excited state properties were used to monitor the formation of these supramolecular structures in situ under kinetic control.

Green/red emission modulation via Tb/Eu co-doping in MOF host for the ratiometric sensing of peroxyacetic acid

As an important oxidant, peracitic acid (PAA) has found wide applications in chemical engineering, agriculture, and industry, as well as public safety. Consequently, the easy-and-fast recognition for PAA is always desired. In this work, we have introduced rare earth-based probes in a microporous host bio-MOF-1, where bio-MOF-1 denotes [Zn8(ad)4(BPDC)6O·2(Me2NH2)+]·G, ad= adenine, BPDC=4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water. Two ligands, 2,2′-bipyrimidine (bpm) and 2,2′-bipyridine (bpy), were coordinated to RE (rare-earth) ions, Tb(III) and Eu(III). The resulting RE probes were co-doped into bio-MOF-1 micropores via ionic exchange with various relative doping levels. The resulting composite samples were characterized by SEM/EDX/elemental mapping, and their doping levels were determined by ICP analysis. The interaction between PAA and ligands (bpm and bpy) adjusted ligand triplet (T1) level, leading to intensity variation of Tb(III) and Eu(III) emission lines (increased Tb(III) emission and decreased Eu(III) emission), which was modulated as a ratiometric sensing signal for PAA. Linear calibration working curves were observed for bpm-based composite samples, with maximum sensitivity of 8.01, response time of ∼36 s, LOD of 0.3 µM, and working region of 0–70 µM.

Photoswitching the injected energy flux via core-sensitized energy migration upconversion for emission-varying STED microscopy.

Stimulated emission depletion (STED) microscopy achieved with lanthanide-doped upconversion nanoparticles (UCNPs) exhibits many outstanding advantages such as low-power illumination, near-infrared (NIR) excitation, and high photostability. However, the available types of UCNP-STED probes are very limited and rely greatly on the specific depletion mechanism. Here, by combining the STED and the energy migration upconversion processes, emissions of Tb3+, Eu3+, Dy3+, and Sm3+ distributed in the shell can all be depleted by interrupting the injected energy flux from the Tm3+-doped core nanoparticles. With the merit of the proposed strategy, new types of UCNP-STED probes are demonstrated to perform emission-varying STED imaging with one single, fixed pair of low-power NIR continuous wave lasers.

Ionic modification on COF with rare earth ions for the selective optical sensing and removal of picronitric acid.

In this work, we reported a modified COF material for trinitrophenol (TPA) ratiometric sensing and removal. Here a cationic covalent organic framework (C-COF) was prepared as host, while two Tb(III)-based ions were doped into C-COF as probe by ionic exchange reaction with probe loading level of ∼15%. In the absence of TPA, weak Tb(III) emission (489nm, 545nm, 585nm) and bright red COF emission were observed (633nm). The addition of TPA increased Tb(III) emission and decreased COF emission, following linear response within TPA concentration region of 0-9μM. Their limit of detection values were determined as 0.9μM and 4.5μM, respectively. Corresponding working equations were fitted as I/I0=1.225+6.914×105M-1[TPA], R2=0.997 for TbCF3-COF and I/I0=1.063+9.222×104M-1 [TPA], R2=0.993 for TbDBM-COF. TbCF3-COF showed better sensing performance than TbDBM-COF, due to its suitable ligand triplet energy level. Their sensing mechanism was revealed as dopant "replacement", where dopant molecules loaded in COF micropore were replaced by TPA molecules, accompanied with energy competing on Tb(III) 5D4 level, showing ratiometric signals. Good selectivity and removal capacity (∼7.4wt%) for TPA were achieved.

Sol-gel synthesis of CaYAlO4:Tb phosphors and their application in detecting nitroaromatic compounds

• CaYAlO 4 :Tb was synthesized by a citrate acid assisted Pechini sol gel approach. • CaYAlO 4 :Tb emits stable red emission under irradiation of ultraviolet in different conditions. • CaYAlO 4 :Tb are good fluorescent probe of p -NT, 1,2-DNT and 4-NT. • The quenching mechanism is of a dynamic quenching one based on inner filter effect. Nitroaromatic compounds are highly toxic, carcinogenic, explosive, and refractory, they do great harm to human health, national security and natural ecosystem, so detecting trace amount of nitroaromatic compounds with high accuracy is crucial to the effective emission control and pollutant treatment. Herein, we synthesized CaYAlO 4 :Tb phosphors by citric acid assisted Pechini sol–gel approach. The samples were characterized by X-ray diffraction (XRD) Fourier transformation infrared (FTIR) spectroscopy, scanning electronic microscopy (SEM), laser particle analyzer, and photoluminescence (PL). The structure and morphology characterizations indicate the samples well crystallize with a K 2 NiF 4 structured CaYAlO 4 at 1100 °C and the samples show irregular morphology with smooth surface and a grain size of about 300 nm. Under irradiation of ultraviolet, CaYAlO 4 :Tb shows the characteristic emission of Tb(III), dominated by the 5 D 4 - 7 F 5 emission at 548 nm. The emission of CaYAlO 4 :Tb can be selectively quenched by nitroaromatic compounds such as p -nitrophenol, 1,2-dinitrobeneze and 4-nitrotoluene. The quenching effect (I 0 /I) can be well fitted into a linear equation, which make CaYAlO 4 :Tb an excellent candidate to detect nitroaromatic compounds. The quenching mechanism is determined to be a dynamic quenching process.

One‐pot synthesis of copper nanocluster/Tb‐MOF composites for the ratiometric fluorescence detection of Cu2+

The increasing degradation of ecosystems due to heavy metal residues has led to environment and food contamination, prompting the development of convenient platforms for monitoring heavy metals. Here, a new dual-emission fluorescent sensor CuNCs@Tb@UiO-66-(COOH)2 for the detection of copper ions (Cu2+ ) has been synthesized using one-pot encapsulation of Tb(III) and glutathione-stabilized copper nanoclusters (CuNCs) into metal-organic frameworks (MOFs) UiO-66-(COOH)2 . In this ratiometric sensor, the fluorescence intensity of Tb3+ decreased significantly upon the addition of Cu2+ , whereas that of CuNCs showed good stability, together with an apparent colour change. Therefore, ratiometric fluorescence detection of Cu2+ can be accomplished by measuring the ratio of the fluorescence intensity at the 450 nm (F450 ) wavelength of CuNCs to the 548 nm (F548 ) emission of Tb3+ in the fluorescence spectra of the CuNCs@Tb@UiO-66-(COOH)2 suspension. Moreover, the obtained fluorescent probe showed good results in the detection of actual samples. This work can provide the basis of method for the exploration of ratiometric fluorescence and visual sensors of trace pollutants analysis in complicated samples.

An ionic covalent organic framework loaded with terbium-based probe for the sensing and removal of chrysolepic acid: Characterization and ratiometric behavior

Chrysolepic acid (CA) is a widely-used chemical product and considered hazardous for ecosystem and human health, which makes its removal as important as its sensing. In this work, a composite structure (denoted as Tb–COF, with a structural composition of C 162 H 120 N 18 O 12 Br 3 ·C 21 H 9 N 3 O 12 Tb 1 ) was synthesized, consisting of an ionic covalent organic framework (denoted as I–COF, with a structural composition of C 162 H 120 N 18 O 12 Br 6 ) and a terbium-based dopant/emitter (denoted as Tb(DPA) 3 3− , DPA = pyridine-2,6-dicarboxylic acid). Tb–COF was identified by means of single crystal analysis, infrared (IR) spectra, X-ray diffraction (XRD), porosity analysis, SEM (scanning electron microscope)/TEM (transmission electron microscope) and elemental composition analysis. The dopant loading level in Tb–COF was determined as 41%. Both green emission from Tb-based dopant and red emission from I–COF host were observed. The presence of CA quenched I–COF emission but enhanced dopant emission, resulting in ratiometric sensing signal. A linear calibration curve was demonstrated, with fitting equation of I/I 0 = 1.223 + 6.709 × 10 5 M −1 [CA], R 2 = 0.996, within [CA] region of 0–9 μM. The key sensing/adsorption process was revealed as the adsorption of I–COF micropores for CA molecules, which endowed Tb–COF with a good selectivity over competing species. I–COF adsorption/removal feature for CA was tentatively evaluated. • An ionic covalent organic framework was synthesized and modified with luminescent ionic Tb(III) emitter. • The as-synthesized Tb–COF showed weak Tb(III) emission and strong red COF emission. • After adding CA, Tb(III) emission was increased with COF emission weakened greatly, showing sensing behavior. • The adsorption and removal performance of Tb–COF was investigated as well.

Analysis of Anion Binding Effects on the Sensitized Luminescence of Macrocyclic Europium(III) Complexes

AbstractFour triazamacrocyclic and two tetraazamacrocyclic ligands carrying two and three coordinating donor groups, respectively, and a carbostyril light‐harvesting antenna were synthesized. The antenna was linked to a macrocycle either via secondary or tertiary amide. Complexation with europium (Eu), gadolinium (Gd), terbium (Tb), and ytterbium (Yb) yielded overall +1 or +2 charged species. Paramagnetic 1H NMR, and steady‐state and time‐resolved luminescence spectroscopies showed that the complexes had 1–3 inner‐sphere water molecules and displayed a variety of coordination geometries in solution. The antennae sensitized Eu(III) and Tb(III) emission with quantum yields of 0.3–4.3 % and 9.9–24.5 %, respectively. The addition of excess fluoride or cyanide to buffered Eu(III) complex solutions resulted in anion‐dependent changes. Fluoride addition increased the Eu(III) luminescence intensity by displacing all inner‐sphere water molecules and stabilizing the +3 oxidation state of Eu. Eu(III) luminescence increased up to 25‐fold for one emitter. Cyanide quenched Eu(III) luminescence in all cases despite partial water ligand displacement.

A Red-Emitting COF Ionic Exchanged With Green-Emitting Tb(III) Complex Anion: Synthesis, Characterization, Ratiometric Emission Sensing, and Removal of Picric Acid.

Picric acid (PA) is an important chemical product which has been widely used in dye manufacturing, antiseptics, and pharmaceuticals. Owing to PA’s extreme electron-deficient structure, its natural degradation is hard, leading to accumulation in the environment and finally threatening the ecosystem and human health. In this case, PA detection and removal becomes more and more important, concerning environmental protection and human health. In this study, an ionic covalent organic framework (I-COF) was synthesized and modified with a luminescent Tb(III) emitter (Tb(DPA)3 3-, DPA = pyridine-2,6-dicarboxylic acid), via ionic exchange. The resulting composite material (Tb-COF) was fully characterized by geometric analysis, IR, XRD, porosity analysis, SEM/TEM, and elemental analysis. It was found that Tb(DPA)3 3- was loaded into the hexagonal cage in an I-COF host with an ionic exchange ratio of 41%. The as-synthesized Tb-COF showed weak Tb(III) emission and strong red COF emission, after adding PA, Tb(III) emission was increased whereas COF emission weakened greatly, showing sensing behavior. Linear working curves were observed with good selectivity. The sensing mechanism was revealed as follows. PA molecules replaced the [Tb(PDA)3]3- component trapped in Tb-COF, releasing free luminescent [Tb(PDA)3]3-. After incorporating PA in the hexagonal cage, the COF emission was quenched. This sensing mechanism ensured a good selectivity over competing species, including cations, anions, and nitrocompounds. The adsorption and removal performance of I-COF for PA were investigated as well.