Potential Fluorescent Sensor Research Articles

Boric-acid-functionalized luminescent sensor for detection of chromate ions in aqueous solution

The development of highly fluorescent materials for detection of environmental contaminants like chromate anions (Cr2O72−) is of great importance. Here, boric acid-coated Eu(III) metal–organic framework (Eu-MOF-B) was successfully synthesized using one pot hydrothermal conditions and further extensively characterized by several spectroscopic and microscopic techniques. The fluorescence spectroscopy investigations indicated the dual-fluorescence emission along with high stability in water. In case of presence of Cr2O72− ion in aqueous samples, the red fluorescence of Eu-MOF-B is selectively quenched but blue fluorescence is enhanced. Hence, the complex could be a potential fluorescent sensor for sensitive detection of Cr2O72− with a low limit of detection of 0.17 ppm.

Na-Ln Heterometallic Coordination Polymers: Structure Modulation by Na+ Concentration and Efficient Detection to Tetracycline Antibiotics and 4-(Phenylazo)aniline.

On the basis of the lanthanide metalloligand [Ln(ODA)3]3- (H2ODA = oxydiacetic acid), three new Na-Ln heterometallic coordination polymers, [Ln(ODA)3Na2]n [Ln = Eu (1) and Gd (2)] and [Tb(ODA)3Na3(H2O)2]n (3), had been assembled by adjusting the concentration of Na+ ions in the reaction system. The investigations of fluorescence sensing showed that 1 could be a ratiometric probe to detect tetracycline (TC) and oxytetracycline (OTC) with high sensitivity and low detection limits, 71.92 ppb for the former and 45.54 ppb for the latter, and 3 could selectively sense 4-(phenylazo)aniline through the turn-off pathway with 14.59 ppb of detection limits. Moreover, the competing and circulating experiments indicated that both 1 and 3 had satisfactory antiinterference and recyclability for the corresponding analytes. All of these results implied that 1 and 3 should be potential fluorescent sensors for the detection of TC/OTC and 4-(phenylazo)aniline, and the possible sensing mechanism had also been discussed in depth.

Achieving Multifunctional Detection of Th4+ and UO22+ in the Post‐Synthetically Modified Metal–Organic Framework and Application of Functional MOF Membrane

AbstractThe field of post‐synthesis modification has aroused widespread concern from diverse perspectives, including chemistry, biology, and material science. Post‐synthesis modification can introduce rich functionality into metal–organic frameworks (MOFs) without destroying the main structure of MOFs. Based on this research status, a series of lanthanide metal–organic frameworks ([Ln2(NH2‐BDC)2.5(CH3COO)(DMA)(H2O)]•DMA, Ln = Pr, Nd, Sm, Eu, Gd and Tb, NH2‐BDC = 2‐aminoterephthalic acid, DMA = N,N‐Dimethylacetamide) with 3D network structures, are synthesized by hydrothermal synthesis. Due to the presence of uncoordinated amino groups in the ligands, a series of post‐synthesis modified compounds are successfully synthesized through aldimine condensation reaction. Based on the good fluorescence properties and stable structure of coordination polymers and post‐synthesis modified compounds in water or organic solvents, they are able to be used as potential fluorescence sensor for the detection of Th4+, UO22+, and Cr2O72−, and the calculation result shows that the post‐synthesis modified compounds are more sensitive to the detection of analytes (Th4+, UO22+ and Cr2O72−) than coordination polymers. In addition, the MOF membrane prepared by self‐assembly of [Eu2(NH2‐BDC)2.5(CH3COO)(DMA)(H2O)]•DMA and ternary soap‐free copolymer (VAc‐AA‐BA) emulsion can be used first for detecting aldehyde vapors.

A dual-emission fluorescence sensor constructed by encapsulating double carbon dots in zeolite imidazole frameworks for sensing Pb2+

A novel dual-emission ratio fluorescent sensor (N-CDs/R-CDs@ZIF-8) has been constructed successfully by introducing nitrogen-doped blue fluorescence carbon dots (N-CDs) and red fluorescence carbon dots (R-CDs) into the synthetic environment of ZIF-8 by a simple stirring method. The synthesized material not only inherits the excellent optical properties of N-CDs and R-CDs and the strong adsorption and accumulation performance of ZIF-8, but also shows strong fluorescence and structural stability in extreme environments. The presence of Pb2+ strongly causes the fluorescence quenching of N-CDs, but has almost no effect on the fluorescence of R-CDs. Therefore, a ratio fluorescence sensor is developed for the determination of Pb2+. Most importantly, the real-time fluorescence response shows that the composite material has a high selectivity and good sensitivity to Pb2+ determination, and the calculated LOD is 4.78 nM(S/N = 3) (0.05–50 μM), indicating that the material can be used as a potential fluorescent sensor for Pb2+ detection.

A novel water-stable luminescent metal complex exhibiting high sensitive and selective detection to Fe3+ and Al3+

The application of metal complexes as fluorescent sensor materials has attracted great attention. In this work, we designed and synthesized a tetraphenyl ethylene-based zinc complex {[ZnLCl]·H2O}n (1), which not only has excellent water stability, but also shows good photoluminescence behavior. These properties endow 1 a good fluorescence detection ability to metal ions. The experimental results also confirm that the fluorescence behavior of 1 can be quenched by Fe3+ or Al3+ rapidly and sensitively. When other metal ions coexist with Fe3+ or Al3+, 1 can still effectively recognize Fe3+ or Al3+. It means that 1 is a potential fluorescent sensor material with super anti-interference ability to detect Fe3+ or Al3+. The reason is that there are weak interactions between Fe3+/Al3+ and oxygen atoms in 1. Since there's the competitive absorption between Fe3+ and 1, the quenching effect coefficient of Fe3+ is larger than that of Al3+ and the quenching effect is better than that of Al3+.

A Novel Water-Stable Luminescent Metal Complex Exhibiting High Sensitive and Selective Detection to Fe3+ and Al3+

The application of metal complexes as fluorescent sensor materials has attracted great attention. In this work, we designed and synthesized a tetraphenyl ethylene-based zinc complex {[ZnLCl]·H 2 O} n ( 1 ), which not only has excellent water stability, but also shows good photoluminescence behavior. These properties endow 1 a good fluorescence detection ability to metal ions. The experimental results also confirm that the fluorescence behavior of 1 can be quenched by Fe 3+ or Al 3+ rapidly and sensitively. When other metal ions coexist with Fe 3+ or Al 3+ , 1 can still effectively recognize Fe 3+ or Al 3+ . It means that 1 is a potential fluorescent sensor material with super anti-interference ability to detect Fe 3+ or Al 3+ . The reason is that there are weak interactions between Fe 3+ /Al 3+ and oxygen and nitrogen atoms in 1 . Since there's the competitive absorption between Fe 3+ and 1 , the quenching effect coefficient of Fe 3+ is larger than that of Al 3+ and the quenching effect is better than that of Al 3+ .

A study of silylated tris(styryl)benzenes as potential fluorescent sensors for aqueous fluoride

Different tris(styryl)benzenes bearing a tert-butyldimethylsilyl (TBDMS) group at the periphery have been efficiently prepared by a straightforward protocol. The potential of these compounds as fluorescent sensors for fluoride has been studied. In all cases, this anion caused significant quenching of the emission intensity upon cleavage of the silyl ether group and the formation of the corresponding phenolate anion. All compounds displayed good selectivity over a variety of other anions. They could sense fluoride ions in aqueous solutions with sensitivity in the lower μM range when dissolved in DMSO, demonstrating the validity of this approach.

Microwave-induced synthesis of a new benzodiazepinone based chemosensor in chloroform under thermal agitation: a potential fluorescent sensor for multi-signaling detection of metal ions

A new fluorescent sensor 5, 10-dihydro-11H-pyrido [3, 2-b][1,5] benzodiazepin-11-one (L) has been synthesized and characterized using conventional spectroscopic techniques. The receptor showed large fluorescence quenching effect with transition metal ions like Ni2+, Co2+, Cu2+ and Fe3+ via internal charge transfer (ICT), and with a detection limit at ppm level. The quenching constant was determined using Stern-Volmer plot. UV–vis titrations of L with selected divalent and trivalent metal ions like Ni2+, Co2+, Cu2+, Pb2+, Cr3+, and Al3+ exhibits specific interaction with red shifts in absorption wavelength. The binding stoichiometry of L with divalent metal ions in the ratio of 4:1 was determined using the Job’s plot. The experimental result of UV–vis absorption of L was found to be in good agreement with the calculated data obtained by Density functional theory (DFT) method. As a representative example, the TD-DFT calculations were used to explain the sensing ability of L towards Cu2+ ion.

A highly selective fluorescent chemosensor probe for detection of Fe3+ and Ag+ based on supramolecular assembly of cucurbit[10]uril with a pyrene derivative

A new fluorescent probe composed of cucurbit[10]uril (Q[10]) and a water-soluble derivative of pyrene, aminopropyl-1-pyrenebutanamide (PBA), is designated. 1H NMR spectroscopy reveals that PBA is encapsulated into Q[10] in an aqueous solution to form a stable 1:1 host-guest inclusion complex of PBA@Q[10]. This complex behaves as a highly selective fluorescence quenching probe for Fe3+ in aqueous solutions that may be attributed to the efficient absorption of Fe3+, which hindering absorption of PBA@Q[10] probe at the excitation wavelength of 332 nm, and competitive experiments for the coexistence of Fe3+ with one or all of the other metal ions (37 metal ions) reveals that the selectivity of PBA@Q[10] to Fe3+ is not disturbed by the addition of 50.0 equiv. of the other metal ions. The limits of detection of Fe3+ was determined to be 0.55 mM. Furthermore, the fluorescence enhancing effect of PBA@Q[10] for Ag+ is detected at the above wavelength. According to the mechanistic studies, the fluorescence enhancing route involves interaction of Ag+ ions with the probe, mainly under an internal charge transfer between Ag+ and the probe. Outcomes of this study suggest that PBA@Q[10] probably functions as a potential and promising fluorescence sensor for monitoring of different polluting metal ions in waste waters.

Dyes based on the 2(1H)‐quinolone skeleton as potential colorimetric and fluorescent sensors for cyanide anions

AbstractThe sensing properties of dyes based on 2(1H) quinolones containing dicyanoethylene groups towards selected anions such as CN−, F−, I−, Cl−, SCN−, CH3COO−, and were evaluated. The spectroscopic responses of these compounds were investigated in a solution of acetonitrile/water (1:9, v/v) and phosphate buffer at a pH of 7.4. These dyes were found to act as efficient colorimetric and high turn–off fluorescent sensors to cyanide anions. The fluorescence intensity was linearly related to the concentration of CN− from 1 to 10 µmol/L, and the detection limits reached a micromolar level of 6.7, 11.1, 3.8 and 7.2 µmol/L for 1‐4, respectively. The cytotoxic effect of the dyes against human neuroblastoma cells (SH‐SY5Y) was also determined by MTT assay. The examined compounds exhibited slight cytotoxicity against cells under experimental conditions.

Synthesis of telechelic PNIPAM ended with 9,10-dihydroacridine group as a recyclable and specific Fe3+ detection fluorescent sensor

A novel telechelic Poly(N-isopropylacrylamide) ended with 4'-(9,10-diphenyl- 9,10-dihydropyridine-9-yl)-[1,1′-biphenyl]-4-amine (DPDHR-NH2) group named as DPDHR-PNIPAM, was designed and synthesized to be used as a potential recyclable Fe3+ ion detective fluorescent sensor. Firstly, DPDHR-NH2 as the central part of the fluorescent sensor was synthesized to react with 2-bromoisobutyryl bromide to form initiator. Then, N-isopropylacrylamide as a monomer was initiated by 2-bromo-N-(4'-(9,10-diphenyl-9,10-dihydroacridin-9-yl)-[1,1′-biphenyl]-4-yl)-2-methylpropanamide (DPDHR-Br) to polymerize into telechelic polymer DPDHR-PNIPAM through atom transfer radical polymerization (ATRP). Lastly, DPDHR-PNIPAM was carefully characterized by FTIR, 1H NMR, elemental analysis, GPC, and UV–vis. At room temperature, DPDHR-PNIPAM displayed high-water solubility, highly specific and sensitive towards Fe3+ detection as low as 1.32 × 10−6 M. The selectivity of DPDHR-PNIPAM toward Fe3+ ion experiment showed it was a turn-off fluorescence response in multi-ion-mixed solution. As a thermosensitive polymer, above the lower critical solution temperature (LCST), the chain of DPDHR-PNIPAM may collapse and change from hydrophilic to hydrophobic to form aggregates and was easy to separate from water to perform recyclable. As a result, it will be a potential fluorescent sensor in the field of tracking Fe3+ in biological processes and environmental monitoring. Meanwhile, the method reported here could provide a method to develop highly effective homogeneous soluble and heterogeneous recoverable fluorescence sensor.

Cranberry Beans Derived Carbon Dots as a Potential Fluorescence Sensor for Selective Detection of Fe3+ Ions in Aqueous Solution.

Recently, synthesis, characterization, and application of carbon dots have received much attention. Natural products are the effectual carbon precursors to synthesize carbon dots with fascinating chemical and physical properties. In this study, the fluorescent sensor of carbon dots derived from cranberry beans without any functionalization and modification was developed. The carbon dots were prepared with a cheap, facile, and green carbon precursor through a hydrothermal treatment method. The synthetic process was toxic chemical-free, convenient, and environmentally friendly. To find the optimized synthetic conditions, the temperature, heating time duration, and carbon precursor weight were evaluated. The prepared carbon dots were characterized by UV light, transmission electron microscopy, Raman, Fourier transform infrared, UV–vis, and fluorescence spectroscopy. The resulting carbon dots exhibit stable fluorescence with a quantum yield of approximately 10.85%. The carbon dots emitted the broad fluorescence emission range between 410 and 540 nm by changing the excitation wavelength and were used for the detection of Fe3+ ions at the excitation of 380 nm. It is found that Fe3+ ions induced the fluorescence intensity quenching of the carbon dots stronger than other heavy metals and the Fe3+ ion detection can be achieved within 3 min. Spectroscopic data showed that the obtained carbon dots can detect Fe3+ ions within the wide concentration range of 30–600 μM with 9.55 μM detection limit.

Four alkaline earth metal (Mg, Ca, Sr, Ba)-based MOFs as multiresponsive fluorescent sensors for Fe3+, Pb2+ and Cu2+ ions in aqueous solution

A series of new alkaline earth-metal organic frameworks (AE-MOFs), i.e. {[Mg2(μ6-L)(μ2-OH2)(H2O)4]·DMF}n (1), [Ca2(μ10-L)(EtOH)]n (2), [Sr(μ6-H2L)(MeOH)]n (3) and {[Ba1.5(μ5-H2L)(μ4-H3L)(H2O)3]·2(H2O)}n(4) were synthesized under solvothermal reaction by employing a symmetrical V-shaped multicarboxylic acid ligand H4L (H4L = 5,5′-oxydiisophthalic acid), resulting in versatile coordination modes as well as various topologies. 1 forms a uninodal 4-connected (66)-dia 3D topology based on dinuclear Mg2(COO)2(μ2-OH2) clusters. 2 displays an unprecedented 3-nodal (5,5,10)-connected 3D net with (424·621)(48·62)2 topology based on 1D [Ca(COO)]n chains and dinuclear Ca2(COO)2 clusters. 3 indicates a uninodal 6-connected 3D net with (410·65)-sma topology based on 1D [Sr(COO)]n chains. 4 features a new 4-nodal (4,5,6,6)-connected net with (43·63)2(46·64)2(46·68·8)(46·69)2 topology based on two types of 1D chains. 1-4 show solid-state fluorescent properties at ambient temperature. Especially, 1 and 2 have multiresponsive recognition of Fe3+ and Pb2+ ions, Fe3+ and Cu2+ ions, respectively, while 3 and 4 show single selective detection for Fe3+ ion, signifying that they could be potential fluorescent sensors for specific heavy metal ions in water system. The sensing mechanism has also been discussed in detail.

BaZrO3:Eu3+ nanophosphor: A potential fluorescent sensor for highly selective and sensitive detection of chromium ions from tannery leather and wastewater

The assessment of Chromium ion in the field of leather tanning industry; either in leathers or waste forms, using fluorescent sensor method, has not been thoroughly explored. Herein, a simple and sensitive fluorescent sensor based on x mol Eu3+:BaZrO3 Nano-phosphor (EBZO) (x = 0.00150, 0.0150, 0.0300, 0.0500 mol) has been prepared and characterized for Cr3+ ion detection in tanning leathers or waste. Eu3+:BaZrO3 Nano-sensor has strong and pure red emission with long lifetime upon UVC excitation; either in solid state or aqueous solutions. The sensing results reveal that EBZO Nano-sensor is quite selective and sensitive towards chromium ion over other metal ions. The assessment of chromium ion has been done using Stern-Volmer quenching method on the red fluorescence emitted from the sensor upon the addition of chromium in aqueous solution. Calibration plot has been achieved over the concentration 1.0–10 × 10−9 molL−1 with a correlation coefficient of 0.978 and a detection limit of 3.8 × 10−9 mol L−1. Optical fluorescence and lifetime measurements confirm that EBZO sensor is statically quenched via columbic interaction mechanism with chromium ions. Optimized EBZO Nano-sensor is successfully applied for Chromium detection in real tanning of leather or other waste samples with high recovery values.

Synthesis of a Novel Pyrazine⁻Pyridone Biheteroaryl-Based Fluorescence Sensor and Detection of Endogenous Labile Zinc Ions in Lung Cancer Cells.

A small extent of endogenous labile zinc is involved in many vital physiological roles in living systems. However, its detailed functions have not been fully elucidated. In this study, we developed a novel biheteroaryl-based low molecular weight fluorescent sensor, 3-(phenylsulfonyl)-pyrazine–pyridone (5b), and applied it for the detection of endogenous labile zinc ions from lung cancer cells during apoptosis. The electron-withdrawing property of the sulfonyl group between the phenyl ring as an electron donor and the pyridone ring as a fluorophore inhibited the intramolecular charge transfer state, and the background fluorescence of the sensor was decreased in aqueous media. From the structure–fluorescence relationship analysis of the substituent effects with/without Zn2+, compound 5b acting as a sensor possessed favorable properties, including a longer emission wavelength, a large Stokes shift (over 100 nm), a large fluorescence enhancement in response to Zn2+ under physical conditions, and good cell membrane permeability in living cells. Fluorescence imaging studies of human lung adenocarcinoma cells (A549) undergoing apoptosis revealed that compound 5b could detect endogenous labile zinc ions. These experiments suggested that the low molecular weight compound 5b is a potential fluorescence sensor for Zn2+ toward understanding its functions in living systems.

A novel sulfur-incorporated naphthoquinone as a selective “turn-on” fluorescence chemical sensor for rapid detection of Ba2+ ion in semi-aqueous medium

A sulfur-functionalised analogue of the naturally available 1,4-naphthoquinone (N) has been synthesized and evaluated as a sensitive and highly selective fluorimetric sensor against the environmentally toxic barium (II) ion in a semi-aqueous medium. The host ligand exhibits a distinct enhancement in its native fluorescence in the presence of barium ions in ethanol/H2O (1:1,v/v). Its sensing activity was further corroborated by a minimum interference offered by a diverse array of other competing metal cations during the fluorimetric sensing of barium ions. The stoichiometry of N:Ba2+ ion system was calculated from the Benesi-Hildebrand plot to be 2:1 with a binding constant of 3.29 mM. The detection limit of the potential fluorescence probe N against aqueous barium ions was observed to be 4.22 mM. In conclusion we propose that sulfur-containing naphthoquinone act as a potential turn-on fluorescence sensor for the selective detection of toxic barium ions in semi-aqueous medium.

Synthesis, characterization and luminescent sensing property of a novel Zn(II)-organic coordination polymer

A novel luminescent Zn(II)-organic coordination polymer {[Zn(asba)(mbix)2(H2O)]·H2O·DMF}n (1) based on the multi-functional 2-amino-5-sulfobenzoic acid (H2asba) and the N-donor flexible bis(imidazole) ligand 1,3-bis(imidazole-1-ylmethyl)benzene (mbix) has been synthesized and structurally characterized. 1 shows excellent hydrolytic stability in water. 1 may be used as a potential candidate for wide band gap semiconductor materials through the analysis of the solid state diffuse reflectance UV–vis spectrum. The fluorescence properties of 1 are greatly dependent on the solvents. 1 exhibits the strongest fluorescence in water. Most interestingly, the fluorescence emission of the aqueous suspension of 1 is selectively quenched by the chromate anions (CrO42−/Cr2O72−) or Fe3+ cation among large pools of the co-existent different anions or metal cations, respectively, revealing that 1 could be used as a potential dual functional fluorescent sensor for trace amounts of the chromate anions or Fe3+ cation. The detection limits obtained through the incremental fluorescence quenching titration experiments reach to sub-ppm level for the Cr(VI) anions (CrO42−/Cr2O72−) and Fe3+ cation, respectively.

One-pot degradation of cellulose into carbon dots and organic acids in its homogeneous aqueous solution

As the abundant biopolymer, cellulose can be used as a feedstock for chemicals and materials. Effective conversion of cellulose by simple processes is a key point. Degradation of cellulose in its homogeneous solution is attractive for the molecular chains are free and spread. Here, microcrystalline cellulose was first dissolved in aqueous solution of NaOH and urea, and then hydrothermal reaction was carried out at various temperature and time. Fluorescence carbon dots (CDs) were generated accompanied with six organic acids: oxalic acid, formic acid, malonic acid, lactic acid, acetic acid, and fumaric acid. The yields of all organic acids and CDs, and the fluorescence quantum yield (QY) of CDs were studied at different reaction conditions. It was found that the maximum yield of organic acids and CDs are 80.1% and 6.03%, respectively, and the highest QY of the CDs is 10.9%. Fluorescence studies reveal that the as-prepared CDs has efficient selectivity and sensitivity toward iron ions in acidic condition, indicating it is a potential fluorescent sensor to the detection of Fe3+. Importantly, it provides a panorama to summary the degradation routes of cellulose in its homogeneous aqueous solution with both organic molecules and CDs as products.

The cationic dye basic orange 21 (BO21) as a potential fluorescent sensor.

The present study investigates the fluorescence properties of BO21 and their dependence on various intracellular conditions. The results obtained with cell-free solutions indicate that the influences of pH and temperature on the fluorescence spectra are negligible, while viscosity, various proteins and heparin have significant influence. In the presence of heparin, a red shift of the emission spectrum (from 515 to 550 nm) is observed, suggesting that this shift cannot simply be attributed to electrostatic interaction between BO21 and the polyanionic heparin, but rather to aggregation of BO21 on the polyanion. In water, the quantum yield of BO21 was found to be 1000 times lower than that of fluorescein, yet surprisingly its fluorescence polarization (FP) was found to be about 40 times higher (FP = 0.470), even though both have similar structures and molecular weights. A thorough analytical and experimental investigation of these phenomena indicates that the very high FP of BO21 in water is a consequence of its very short lifetime. However, upon the addition of heparin to aqueous BO21, the fluorescence lifetime (FLT) of BO21 increases from τ = 10.35 to 56.5 ps, with a consequent dramatic drop in its fluorescence polarization from 0.470 to 0.230. From its behavior in aqueous glycerol solution, it is hypothesized, with support from theoretical calculations, that BO21 is a molecular rotor. Using these properties, BO21 may be a good candidate as a sensor, for example, of heparin levels in blood or of intracellular viscosity.

Controlling Crystal Structures and Multiple Thermo- and Vapochromic Behaviors of Benzimidazole-Based Squaraine Dyes by Molecular Design and Solvent Adjustment.

Organic micro- and nanostructures are expected to be promising candidates for micro- and nanophotonic materials with desirable properties owing to their low cost, flexible molecular design, and tunable self-assembly. Among these candidates, well-known squaraine dyes (SQs) have rarely been investigated because of their nonfluorescent properties in the solid state and because their optical behavior varies with changes in morphology. In this contribution, two novel 1,2-SQs, SQM and SQB, with strong bright-yellow to red fluorescence emission in the crystalline state, were designed and structured at the molecular level and by solvent adjustment. Their self-assembly behavior was studied, and it was revealed that the SQM assembly provided 1D microrods, whereas 1D microrods (Z-SQB⋅CH2 Cl2 ) and 2D microplates (E-SQB⋅2 CH3 OH) could be obtained from SQB assemblies through a solution-based self-assembly method. The varied assembly behaviors of these SQs were attributed to different π-π stacking interactions that resulted in different molecular conformations and packing modes. These assemblies exhibited distinct optical properties, and in particular, SQB⋅solvent assemblies showed multiple thermo- and vapochromic effects. Thus, the SQB assemblies are potential fluorescent sensors for organic solvent vapors. More importantly, favorable optical-waveguide properties were observed in these SQ-based microstructures.