Detection Of Nitroaromatic Compounds Research Articles

White‐Light‐Emitting Ln‐MOF as Luminescent Probe for Selective Detection of Nitroaromatic Compounds

AbstractMetal‐organic frameworks (MOFs) as an efficient and convenient sensing material for environmental pollutants have attracted widespread attention in recent years. Here in, we synthesized a series of lanthanide co‐doping MOFs, EuxTb1‐x‐MOFs (x=0, 0.005, 0.00667, 0.01, 0.02 and 1) under solvothermal conditions. The luminescence colors can be adjusted by changing metal molar mass ratios and altering excitation wavelength. Fortunately, a near white‐light‐emitting material Eu0.01Tb0.99‐MOF was obtained under the excitation at 350 nm, whose CIE coordinates of (0.3444, 0.3409) are very close to standard white light coordinates (0.3333, 0.3333). We further studied the fluorescence sensing performances of Eu‐MOF, Tb‐MOF and Eu0.01Tb0.99‐MOF towards NACs. The results indicate that all MOFs can selectively detect 4‐nitroaniline, 4‐nitrophenol and 2‐nitrophenol with good sensitivity and recyclability.

An Electrochemical Sensor Based on 3D Graphene‐Cyclodextrin Nanohybrid for Enhanced Sensitivity Detection of Nitroaromatic Compounds

This study presents an electrochemical sensor for sensitive detection of nitroaromatic compounds using a three‐dimensional (3D) porous graphene with polyoxypropylene supported reduced graphene oxide (PEA‐RGO) and embedded β‐cyclodextrins (β‐CD). First, PEA‐RGO was synthesized by the condensation reaction between graphene oxide (GO) and amino‐terminated polyoxypropylene (PEA), followed by hydrazine hydrate reduction. Then, β‐CD was embedded into the porous of the above 3D graphene to obtain PEA‐RGO/β‐CD nanohybrid. Various characterization techniques, such as microscopy imaging, infrared spectrometry, thermal analysis and electrochemical measurements, were employed to confirm the successful synthesis and unique 3D architecture structure of PEA‐RGO/β‐CD. Afterwards

Metal-induced assembly of two novel MOFs: Sensitive fluorescence sensing properties and insights into mechanisms

Two new MOFs, namely, [Pb2(2-CPP)2(H2N-bpdc)]n (1) and [Cd(3-CPP)2]n (2), have been prepared by using N- and O-donor ligands and metal ions Pb2+, Cd2+ under hydrothermal conditions. The single-crystal X-ray diffraction analysis was used to measure the crystal structure. The complex 1 is one-dimensional chain structures, and it can further form two-dimensional and three-dimensional supramolecular structures through π-π stacking. The complex 2 is a two-dimensional layered structure, which can form three-dimensional supramolecular structure through π-π interaction. The synthesized MOFs exhibit ligand-based luminescence, which can be attributed to the coordination effect. Due to its excellent fluorescence properties, complex 2 can be used for selective and sensitive detection of nitro aromatic compounds (NAC) and metal ions. The results show that the complex 2 could quickly detect Cr2O72−, nitrobenzene and Fe3+by fluorescence quenching, and had good anti-interference and cycle stability, so it was a potential chemical fluorescence sensing material. The identification mechanism of 2 is discussed by electron transfer analysis method and density functional theory (DFT) calculation.

Synthesis of octa-benzothiazole functionalized tetraphenylethylene and their explosive sensing properties

The detection of nitroaromatic compounds (NACs) such as 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) is critical for environmental monitoring and security, due to their extensive use in explosives and the associated health risks. However, current methods for detecting these compounds face challenges in sensitivity, specificity, and practicality. In this study, a new benzothiazole functionalized tetraphenylethylene molecular scaffold (TPE-BTH) have been successfully synthesized and characterized for its potential in explosive sensing. The TPE-BTH compound exhibits distinct UV–Visible and fluorescence emission behaviors in different solvent polarities. A remarkable feature of TPE-BTH is its pronounced fluorescence quenching upon the addition of 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP) in a dichloromethane solution, highlighting its sensitivity and potential utility in explosive detection. The detection limits for TNP and DNP were determined to be remarkably low at 7.28 × 10-8 M and 1.23 × 10-8 M, respectively. Through theoretical investigations, we explored the interaction mechanisms between TPE-BTH and TNP, uncovering the roles of internal hydrogen bonding within picric acid and π-π interactions as well as dipole interactions between the molecules. Additionally, 1H NMR was utilized to elucidate the interaction mechanisms between TPE-BTH and TNP. The development of TPE-BTH as a molecular scaffold for NAC detection significantly contributes to the field of explosive sensing and environmental monitoring.

Designing a calixarene-based {Zn24} coordination cage as a multifunctional sensor

Solvothermal method was chosen to construct a porous zinc-calixarene coordination cage (SWU-3): [Zn24(TC4A-SO2)6(BTC)8(H2O)6] (H4TC4A-SO2 = p-tert-butylsulfonylcalix[4]arene, H3BTC = 1,3,5-benzenetricarboxylic acid) by ZnCl2, H3BTC and H4TC4A-SO2. SWU-3 shows certain water stability and excellent luminescence property. In the fluorescence test, SWU-3 exhibits different fluorescence sensing behaviors for detecting Fe3+, CrO42-, Cr2O72- and iodine (I2), the LOD values are 2.21 × 10-5, 2.740 × 10-5, 3.066 × 10-5 and 6.673 × 10-6 mol/L, respectively. Moreover, nitroaromatic compounds (NACs) can also be detected by SWU-3. These results prove that SWU-3 reveals great potential as a fluorescence sensor for ions, I2 and NACs detection.

Selective sensing of picric acid using a Zn(II)-metallacycle: experimental and theoretical validation of the sensing mechanism and quantitative analysis of sensitivity in contact mode detection.

A combination of N,N',N''-tris(3-pyridyl)-1,3,5-benzenetricarboxamide (L1) and p-chlorobenzoic acid (HL2) with Zn(NO3)2·6H2O resulted in the formation of a dinuclear metallacycle [ZnL1(L2)2(DMF)2]2 (1(DMF)4). In 1(DMF)4, the Zn(II) centre adopts a square pyramidal geometry, while one of the pyridyl N out of the three pyridyl groups in L1 remained uncoordinated. Solvated DMF molecules are present in 1(DMF)4. The structural and chemical nature of 1(DMF)4 is effective for it to act as a potential fluorescent probe for the detection of nitroaromatic compounds. It is observed that the probe, 1(DMF)4, could selectively detect picric acid (PA) among various aromatic compounds in solution (DMSO), while the solid state (contact mode) detection showed a positive sensing response for the nitrophenols (PA: 87% quenching efficiency, 2,4-dinitrophenol (2,4-DNP): 57% quenching efficiency and 4-nitrophenol (4-NP): 40% quenching efficiency). The limit of detection (LOD) of PA by the probe in DMSO was found to be 6.8 × 10-11 M while the LOD in contact mode detection was estimated to be 0.49 ng cm-2. The mechanism of selective detection of PA by 1(DMF)4 in DMSO was analyzed through photophysical studies, 1H-NMR experiments and also by density functional theory (DFT) calculations. The effective overlap of the absorption spectrum of 1(DMF)4 and emission spectrum of PA in DMSO suggests that the Förster resonance energy transfer (FRET) is responsible for quenching phenomena in DMSO. The DFT calculations and molecular docking studies showed the adduct formation due to the favorable interactions between 1(DMF)4 and PA in DMSO, while negligible interactions were observed between 1(DMF)4 with other aromatic compounds. The experimental and DFT studies showed that the efficient sensing ability of PA by 1(DMF)4 in the solid-state was due to photoelectron transfer (PET) and FRET phenomena described herein.

Functionalised Al(III) metal organic frameworks for fluorescence sensing of nitroaromatic vapours

Mixed-ligand Al(iii) metal–organic frameworks of the MIL-53 structural type show strong fluorescence quenching upon interaction with vapour-phase nitroaromatic compounds.

Morphology study of light– and pH–responsive amphiphiles with DSA for detection of nitrobenzene derivatives

Supramolecular molecular self–assemblies with 9, 10-distyrylanthracene (DSA) frameworks have good application prospects in fluorescent probes and optical materials owing to the unique AIE effect of the DSA unit. In this study, amphiphilic rod–coil molecules with rigid DSA parts and flexible oligoether chains were designed and synthesised, and their assembly capacities were investigated. The amphiphilic molecule with a lateral methyl unit in the coil branch formed worm–like supramolecular assemblies, while the molecule without lateral group self–assembled into an interwoven ribbon like structure in aqueous solution. This is due to noncovalent molecular interactions, such as the π–π stacking interaction of the rigid segments for the former or the hydrophilic–hydrophobic effect of molecules in the aqueous solution for the latter. Interestingly, under irradiation with 365 nm UV light, the original UV absorption of the molecule decreased and fluorescence quenching occurred, accompanied by a decrease in the size of the original aggregates, which became more apparent with as irradiation time increased, indicating the presence of photo-degradation. These molecular morphologies were also significantly influenced by the pH of the aqueous solution and produced nanoparticles of various sizes. Furthermore, we investigated the adsorption capacity of nitro compounds and found that molecular aggregates could be used for the detection of nitroaromatic compounds with strong electron-withdrawing groups.

Anthracene and tetraphenylsilane based conjugated porous polymer nanoparticles for sensitive detection of nitroaromatics in water

Conjugated porous polymers (CPPs) are a kind of promising sensing materials for the detection of nitroaromatic compounds, but their sensing applications in aqueous media are limited because of their poor dispersity or solubility in water. In this study, we prepared anthracene and tetraphenylsilane based CPPs named PSiAn by conventional Suzuki coupling and Suzuki-miniemulsion polymerization, respectively. The structure, morphology and porosity of the CPPs were characterized by Fourier Transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), transmission electron microscope (TEM) and N2 sorption isotherm, respectively. Both of the CPPs have porous structure which is beneficial for the adsorption and diffusion of the analytes within them. The particle size of PSiAn nanoparticles prepared by Suzuki-miniemulsion polymerization is 10–40 nm from the TEM image, which facilitates the dispersion in the aqueous phase. Combined with the porosity and nanoparticle morphology, PSiAn nanoparticles realized the efficient photoluminescence (PL) sensing of nitroaromatic explosives in aqueous phase. The limit of detection (LOD) and limit of quantitation (LOQ) of PSiAn nanoparticles for 2,4,6-trinitrophenol (TNP) detection in the pure aqueous phase are 0.33 μM and 1.11 μM, respectively. Meanwhile, the good selectivity and anti-interference in presence of other nitro-compounds were observed. Furthermore, the spike/recovery test for the TNP detection in real water samples by PL sensing based on PSiAn nanoparticles indicates the quantitative recovery of TNP from 100.74 % to 101.00 %. The electrochemical test, ultraviolet–visible absorption spectra, excitation and emission spectra, and time-resolved PL spectra were investigated to explore the PL sensing mechanism. As a result, it is found that the fluorescence inner filter effect might be the predominant quenching mechanism during the detection of nitrophenolic compounds such as TNP and 4-nitrophenol (4-NP).

Polymers and Polymer-Based Materials for the Detection of (Nitro-)explosives.

Methods for the remote detection of warfare agents and explosives have been in high demand in recent times. Among the several detection methods, fluorescence methods appear to be more convenient due to their low cost, simple operation, fast response time, and naked-eye-visible sensory response. For fluorescence methods, a large variety of fluorescent materials, such as small-molecule-based fluorophores, aggregation-induced emission fluorophores/materials, and supramolecular systems, have been reported in the literature. Among them, fluorescent (bio)polymers/(bio)polymer-based materials have gained wide attention due to their excellent mechanical properties and sensory performance, their ability to recognize explosives via different sensing mechanisms and their combinations, and, finally, the so-called amplification of the sensory response. This review provides the most up-to-date data on the utilization of polymers and polymer-based materials for the detection of nitroaromatic compounds (NACs)/nitro-explosives (NEs) in the last decade. The literature data have been arranged depending on the polymer type and/or sensory mechanism.

Y-Shaped Fluorophores Based on N(2)-Aryl-1,2,3-triazoles: Synthesis and Study of Photophysical and Chemosensor Properties for the Detection of Nitroaromatic Compounds

Y-Shaped Fluorophores Based on N(2)-Aryl-1,2,3-triazoles: Synthesis and Study of Photophysical and Chemosensor Properties for the Detection of Nitroaromatic Compounds

Optical detection of nitroaromatic compounds using MAPbBr3 at room temperature

Optical detection of nitroaromatic compounds using MAPbBr3 at room temperature

Fluorescent Materials Containing Polycyclic Aromatic Compounds: synthesis, Fluorimetric Detection of Nitroaromatic Compounds and Color Properties

Schiff bases with pyrene, anthracene or naphthalene groups can act as simple, sensitive, and selective sensors for the detection of trace explosives. We have prepared three new types of Schiff bases with fluorescent properties as fluorescent probes for use in the fluorescence detection of explosives. The detection properties of the synthesized compounds of photophysical and fluorescent explosives were investigated. Spectroscopic methods were used for the structural characterization of the compounds. Within the scope of the study, compounds (A, B and C) were used as fluorescent probes in the detection of some explosives and the data obtained were recorded. Instead of the quenching effect expected by the explosives on the emissions of the compounds, it was observed in some experiments that the emission intensity due to aggregation increased. In addition, the color measurements (CIE standards) and Color temperature (CCT) of the compounds were calculated.

A Quenched Fluorescence‐based Assay for Selective Detection of Nitroaromatic Compounds using Pyrene‐Appended Oxacalix[4]arene Host

AbstractA novel pyrene appended supramolecular assembly (PAOC) has been fabricated by reacting intermediate‐pyren‐1‐ylmethyl 2‐chloroacetate (PMCA) with oxacalix[4]arene and characterized by 1H NMR, 13 C NMR and ESI‐Mass. PAOC works as fluorescent chemosensor for the selective detection of nitroaromatic compounds such as 4‐nitrophenol (4NP) and 2,4,6‐trinitrophenol (TNP). The binding mechanism between PAOC and the analytes were investigated through various spectroscopic techniques, and the results indicate a strong interaction between the two. The fluorescence intensity of PAOC is quenched upon interaction with nitroaromatic compounds due to a photoinduced electron transfer process, which was validated by DFT calculations. The sensor exhibits excellent selectivity and sensitivity towards TNP over other nitroaromatic compounds. The detection limits for TNP and 4NP were found to be 1.6 μM and 1.9 μM, respectively. PAOC's detection results in real water samples are remarkable. This study provides a new approach to develop highly selective and sensitive chemosensor for the detection of nitroaromatic compounds, which have significant environmental and health hazards.

Eu doped Zn-MOF nanofiber fluorescent membrane and its multifunctional detection of nitroaromatic compounds and Fe3+

Metal-organic framework (MOF) fluorescent materials have significant advantages in detecting organic pollutants and metal ion pollution. A zinc metal organic framework nanofiber fluorescent membrane (Zn(Eu)-MOF@PAN NFM) was prepared by doping the lanthanide metal Eu using an electrospinning and impregnation process. The structure and morphology of the membrane was characterized by SEM, XRD, FT-IR and XPS. The results show that the membrane has good fluorescence performance and can successfully and efficiently detect nitrobenzene (NB; detection limit = 0.861 ppm, Ksv = 0.143 ppm−1), 4-nitrophenol (4-NP; detection limit = 0.631 ppm, Ksv = 0.178 ppm−1), benzaldehyde (BA; detection limit = 0.981 ppm, Ksv = 0.051 ppm−1) and Fe3+ ions (detection limit = 3.418 ppm, Ksv = 3.210×10−3 ppm−1) in solution. In terms of repeatability and stability, the test results are obviously better than the property of the powder.

A water-soluble small molecular fluorescent sensor based on phosphazene platform for selective detection of nitroaromatic compounds.

Nitro-aromatic compounds have a deleterious effect on the environment and they are extremely explosive. Therefore, societal concern about exposure to nitro-aromatic compounds encourages researchers to develop selective and sensitive detection platforms for nitro-aromatic compounds in recent years. In this paper, a new 100% water-soluble cyclotriphosphazene-based bridged naphthalene material (4) was prepared as a small molecule fluorescent sensor for ultra-selective detection of nitro-aromatic compounds. The chemical structure of 4 was extensively characterized by mass spectrometry and nuclear magnetic resonance spectroscopies (31P, 13C, 1H). The photo-physical properties of the newly developed sensing system were investigated by steady-state fluorescence and UV-Vis absorption spectroscopies. The fluorescence sensor behaviors were extensively evaluated after treatment with the most commonly used metal cations, anions, competitive aromatic compounds, saccharides, and organic acids. The developed fluorescent sensing system (4) demonstrated ultra-selective fluorescence "turn-off" signal change toward nitro-aromatic compounds while other tested competitive species caused negligible changes. To evaluate selectivity, time-resolved, steady-state 3D-fluorescence and UV-Vis absorption spectroscopies were used in fully aqueous media. Moreover, theoretical calculations (density functional theory and time-dependent density functional theory) were applied and discussed to identify fluorescence sensing mechanisms toward nitroaromatic compounds for the presented sensing system.

Synthesis, structural characterization and determination of the nitro-containing explosives detection potential of supramolecular lanthanum complex and Lanthana nanoparticles

A novel nanoparticle sized complex, [La(HO-C6H4-CH2COO)3(H2O)].(H2O), has been prepared by the reaction of LaIII ion and a versatile carboxylate ligand, 4-hydroxyphenylacetatic acid. The obtained complex was structurally characterized by using single crystal X-ray diffraction, SEM-EDS and FT-IR spectroscopy. Then, we synthesized La2O3 nanoparticles by the calcination of the complex and characterized its features by powder X-ray diffraction and SEM analysis. Average particle sizes of the complex and La2O3 particles were determined 19.6 nm and 44.02 nm, respectively. The bulk form of La2O3 (bulk) was bought commercially. The linear optical absorption traces of all materials were recorded by using UV–Vis spectrophotometer. The nitro-containing explosive detection potentials of complex, nanoparticles and bulk materials were investigated by using fluorescence spectrophotometer which is measured the fluorescence quenching of these three materials in nitro-containing media. It was found that all of the studied materials are good candidates especially for the detection of nitroaromatic compounds.

Fabrication of SPR triggered Ag-CuO composite from Cu(II)-Schiff base complex for enhanced visible-light-driven degradation of single and binary-dyes and fluorometric detection of nitroaromatic compounds

Fabrication of SPR triggered Ag-CuO composite from Cu(II)-Schiff base complex for enhanced visible-light-driven degradation of single and binary-dyes and fluorometric detection of nitroaromatic compounds

Unusual ‘Turn-on’ Ratiometric Response of Fluorescent Porphyrin-Pyrene Dyads to the Nitroaromatic Compounds

Detection of nitroaromatic compounds (NAC) is an important task since these substances are hazardous to both the biosphere and the society. Fluorescent sensors developed for NAC detection usually demonstrate a ‘turn-off’ response to the analyte, while ‘turn-on’ sensors are rarely reported. Here, we present a showcase report on new pyrene-imidazoporphyrin dyads that demonstrate an unusual analytic response to NAC with clear ‘turn-on’ behavior followed by an unexpected appearance of a new band, which can be ascribed to exciplex emission. The porphyrin backbone of the dyad also allows registration of its own fluorescence, providing an internal reference signal for ratiometric detection. The association constants in the order of 104 M−1 are reported.

A Novel Composite of Zinc-based Metal Organic Framework Embedded with SnO2 Nanoparticle as a Photocatalyst for Methylene Blue Dye Degradation as well as Fluorometric Probe for Nitroaromatic Compounds Detection.

A facile bottom up synthesis technique is opted for the preparation of novel composite SnO2@Zn-BTC. This synthesized composite is fully characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and Elemental mapping techniques. Optical analysis was performed using UV-Visible absorption spectroscopy and fluorescence studies. Further this composite was utilized for the first time as a photocatalyst for methylene blue (MB) dye degradation under sunlight irradiation. This photocatalyst shows degradation efficiency of 89% within 100min of exposure of sunlight. In addition to that, the synthesized composite can be utilized as a fluorescence probe for detection of NACs via 'turn-off" quenching response. This composite is extremely sensitive towards 3-NA in aqueous medium with quenching efficiency of 75.42%, which is highest quenching rate till reported. There occurs no interference for detecting 3-NA in the presence of other NACs. The linear fitting of the Stern-Volmer plot for 3-NA shows large quenching constant (KSV) of 0.0115ppb-1 with correlation coefficient R2 = 0.9943 proves higher sensitivity of composite in sensing process. The outstanding sensitivity of composite for 3-NA is certified by the low detection limit (LOD) of 25ppb (0.18µM). Photoinduced Electron Transfer (PET)and Fluorescence Resonance Energy Transfer (FRET) are the mechanisms used for clarification of quenching response of PL intensity by NACs via density functional theory (DFT) calculations and extent spectral overlap, respectively. Hence, synthesized composite is verified as multi-component system to act as excellent photocatalyst as well as fluorescent sensor.