Detection Of Nitroaromatics Research Articles

Detection of nitroaromatics by a Zn(II)-containing coordination polymer derived from a 1,2,3-triazole-based tricarboxylate ligand

The Dimroth azide–enolate cycloaddition between dimethyl 5-azidoisophthalate and ethyl acetoacetate was used to generate 5-(4-carboxy-5-methyl-1H-1,2,3-triazol-1-yl)isophthalic acid (H3L) as a novel tricarboxylate ligand with a 1,2,3-triazole ring in the central unit with a view to employ it in the preparation of coordination polymers. The reaction of this ligand with Zn(NO3)2·6H2O in a mixture of N,N-dimethylformamide (DMF) and water at 95 °C for 72 h afforded [Zn4L2(OH)2(H2O)DMF2]n, which has been characterized by single crystal X-ray crystallography, infrared spectroscopy, thermogravimetry, powder X-ray diffraction and elemental analysis. The fluorescence of this coordination polymer was investigated, and its ability to detect various nitroaromatics by fluorescence quenching was examined. 4-Nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol and 4-nitrotoluene have been identified as the aromatic nitroderivatives for which the coordination polymer exhibits a fluorescence quenching in the range of 91% to 82%.

Advance Progress on Luminescent Sensing of Nitroaromatics by Crystalline Lanthanide-Organic Complexes.

Water environment pollution is becoming an increasingly serious issue due to industrial pollutants with the rapid development of modern industry. Among many pollutants, the toxic and explosive nitroaromatics are used extensively in the chemical industry, resulting in environmental pollution of soil and groundwater. Therefore, the detection of nitroaromatics is of great significance to environmental monitoring, citizen life and homeland security. Lanthanide-organic complexes with controllable structural features and excellent optical performance have been rationally designed and successfully prepared and used as lanthanide-based sensors for the detection of nitroaromatics. This review will focus on crystalline luminescent lanthanide-organic sensing materials with different dimensional structures, including the 0D discrete structure, 1D and 2D coordination polymers and the 3D framework. Large numbers of studies have shown that several nitroaromatics could be detected by crystalline lanthanide-organic-complex-based sensors, for instance, nitrobenzene (NB), nitrophenol (4-NP or 2-NP), trinitrophenol (TNP) and so on. The various fluorescence detection mechanisms were summarized and sorted out in the review, which might help researchers or readers to comprehensively understand the mechanism of the fluorescence detection of nitroaromatics and provide a theoretical basis for the rational design of new crystalline lanthanide-organic complex-based sensors.

Two anthracene-based zirconium metal–organic frameworks with fcu and hcp topologies as versatile fluorescent sensors for detection of inorganic ions and nitroaromatics

Two anthracene-based zirconium metal–organic frameworks (UiO-68-AN-fcu and UiO-68-AN-hcp) with blue emission were synthesized by the solvothermal reaction of ZrCl4 with anthracene-based ligand 4,4′-(9,10-anthracenediyl)dibenzoic acid. The two MOFs inherited the luminescence properties of anthracene-based ligand and exhibited different topologies due to the change of connection mode of Zr-O clusters. The two stable anthracene-based zirconium MOFs served as luminescent sensors for selectively detecting 2-nitrophenol, Fe3+ and Cr2O72−. UiO-68-AN-hcp with flower morphology exhibited stronger quenching effect for 2-nitrophenol, Fe3+ and Cr2O72− by comparing to UiO-68-AN-fcu. Adsorption tests, fluorescence lifetime and spectroscopy studies demonstrated that the fluorescence responses of MOFs for analytes can be primarily attributed to the dynamic quenching mechanism involving energy and electron transfer. These results revealed that the combination of luminescent anthracene-based ligand and Zr-O clusters is a feasible strategy to construst MOFs-based fluorescent sensors.

Dansyl-based fluorescent sensor for highly sensitive detection of nitroaromatics in solution

Dansyl-based fluorescent sensor for highly sensitive detection of nitroaromatics in solution

Pyrene, Anthracene, and Naphthalene-Based Azomethines for Fluorimetric Sensing of Nitroaromatic Compounds.

Special attention is given to the development of rapid and sensitive detection of nitroaromatic explosives for homeland security and environmental concerns. As part of our contribution to the detection of nitroaromatic explosives, fluorescent materials (A), (B) and (C) were synthesized from the reaction of 1,2-diaminocyclohexane with pyrene-1-carbaldehyde, anthracene-9-carbaldehyde and 2-hydroxy-1-naphthaldehyde, respectively. The structures of the prepared fluorescent azomethine probes were confirmed using FTIR, 1H-NMR and 13C-NMR spectroscopies. The basis of the study is the use of the synthesized materials as fluorescent probes in the photophysical and fluorescence detection of some nitroaromatic explosives. Emission increases occurred due to aggregation caused by π-π stacking in synthesized azomethines. To measure the nitroaromatic detection capabilities of fluorescence probes, fluorescence titration experiments were performed using the photoluminescence spectroscopy. It was observed that compound A containing pyrene ring provided the best emission intensity-increasing effect due to aggregation with the lowest LOD value (14.96μM) for the sensing of 4-nitrophenol. In compounds B and C, nitrobenzene with the lowest LOD (16.15μM and 23.49μM respectively) caused the most regular emission increase, followed by picric acid.

Fluorescence Sensing of pH and p-Nitrophenol Using an AIEE Active Pyridoxal Derived Schiff Base.

An easy-to-prepare aggregation-induced emission enhancement (AIEE) active Schiff base NPY was synthesized by condensing vitamin B6 cofactor pyridoxal with 3-hydroxy-2-naphthoic hydrazide, and employed for the fluorescent sensing of pH and p-nitrophenol (p-NP). The AIEE phenomenon of NPY was investigated in mixed DMSO/H2O medium. The weakly yellow-fluorescent NPY (λem = 535nm) in pure DMSO turned to a bright cyan-fluorescent NPY (λem = 490nm) upon addition of poor solvent water. The DLS and SEM analyses supported the self-aggregation of NPY that restricted the intramolecular rotation and activated the excited state intramolecular proton transfer (ESIPT) process. The AIEE luminogen (AIEEgen) NPY containing 90% of water fraction (fwater) was employed for the fluorescent sensing of pH. AIEEgen NPY displays three distinct fluorescent pH windows: non-fluorescent below pH 3.0 and above pH 10.0, cyan fluorescent between pH 3.0 to 8.0, and yellow fluorescent between pH 8.0 to 10.0. AIEEgen NPY was also applied for the detection of nitroaromatics in HEPES buffer (10% DMSO, 10 mM, pH 7.0). The addition of p-NP selectively quenched the fluorescent intensity of AIEEgen NPY with an estimated detection limit of 1.73 µM. The analytical utility of AIEEgen NPY was examined by quantifying p-NP in different real water samples.

Fluoranthene-based derivatives for multimodal anti-counterfeiting and detection of nitroaromatics

Two novel fluoranthene ensembles with ethyl alcohol (FOH) and ethanethiol (FSH) functionality with distinct diagonal and ladder arrangements in the crystal lattices were developed for Latent Fingerprints (LFPs) towards analysis of explosives.

Sensitive turn-off detection of nitroaromatics using fluorescent tetraphenylethylene phosphonate derivative

The derivatisation of tetraphenylethylene is broadly utilized to synthesize molecular sensor for detecting explosives among other analytes, the effects of such alteration have been little investigated. Herein, we report the sensing of various nitro phenols using fluorescence signals produced by (4-(1, 2, 2-tris (4-phosphonophenyl) vinyl) phenyl) phosphonic acid octasodium salt (TPPE). It is observed that the fluorescence of TPPE at 411 nm and 432 nm are quenched in the presence 2,4,6-trinitrophenol (TNP) via electron transfer between weak TPE donor and acceptor mechanism. Moreover, TPPE – TNP association is based on non-covalent interaction including hydrogen-bonding and electrostatic interactions. TPPE shows strong binding affinity and selectivity towards TNP over various other nitroaromatic analytes. The sensing detection limit (LOD) towards TNP is 4.58 × 10−9 M. In detailed molecular simulation experiments are performed to investigate the non-covalent interaction, oscillation frequency, possible transitions and energy levels of molecular complexation between TPPE and TNP. This study supports the sensing mechanism of TPPE towards TNP, suggesting suitable interaction mode between the receptor and PA.

Tough lanthanide luminescent hydrogel for nitroaromatics detection

Luminescent hydrogels have received considerable attention in the application of sensors. Nitroaromatics are harmful to human health and can be carcinogenic. Some skin allergies and central nervous system injuries may also be attributed to the over exposure to nitroaromatics. Thus, nitroaromatics sensor with fast detection and low detection limit is highly desirable. Herein, novel tough hydrogels were prepared by introducing hydrogen bonds and covalent bonds into the interpenetrating networks of modified chitosan and poly(vinyl alcohol) (PVA) via frozen-thawing induced chemical cross-linking. The synthesized hydrogels exhibit high mechanical strength (0.23 MPa tensile strength at 140% tensile strain, 1.0 MPa compressive strength at 80% compressive strain). Strong green emission was realized by energy transfer from the modified chitosan to Tb3+ via the so-called “antenna effect.” The prepared luminescent hydrogels show an excellent detection effect on nitroaromatic compounds and its detection limit can reach ppm-level. The hydrogels also exhibit good reversibility and a fast “off–on” fluorescence switching process. This work may open up a new way for the development of stable, rapid, and reusable sensors for the detection of harmful nitroaromatics.

Photophysical and Fluorescence Nitroaromatic Sensing Properties of Methylated Derivative of a Pamoic Acid Ester.

Rapid and selective detection of nitroaromatic explosives is very important for public safety, life, and environmental health. Current instrumental techniques suffer from high cost and poor site used. In order to investigate fluorescence sensing of nitroaromatics, we prepare a new small fluorescence probe derived from pamoic acid. This study covers the synthesis of Pamoic acid based [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) material and characterization of its structure. The methylation of Pamoic acid ester, which we have successfully synthesized in our previous studies, was carried out in this study. Determination of the photophysical and fluorescent nitroaromatic detection properties of the compound forms the basis of the study. Structural characterization of the synthesized compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) was characterized using spectroscopic methods. In addition, Molecular structure of the synthesized compound was determined by single crystal X-ray diffraction studies. In the final step, compounds [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) and [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) were tested as fluorescent probes for the detection of some nitroaromatic explosives. It is seen that Nitrobenzene provides the best quenching effect on the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) containing the -OH group, with lowest the limit of detection (LOD) value. It was observed that Picric acid provided the best quenching effect with lowest the limit of detection (LOD) value in the compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) obtained by methylation of the -OH group in the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1).

Electrochemical sensing platform for the detection of nitroaromatics using g-C3N4/V2O5 nanocomposites modified glassy carbon electrode

Rapid, reliable, cost-effective and trace-level detection of nitroaromatic toxins is becoming increasingly important because of their carcinogenic nature, and their presence in water sources as an environmental contaminant. The present study reports the development of an electrochemical sensing platform based on g-C3N4/V2O5 (VOCN) nanocomposites modified glassy carbon electrode (GCE) for the effective detection of nitroaromatics. The VOCN nanocomposites were synthesized via wet impregnation method, and were characterized by XRD, FT-IR, HRSEM and XPS techniques. The electrochemical behavior of four nitroaromatics (4-NP, DNP, DNT and TNP) were investigated on seven nanomaterials-based sensors using cyclic voltammetry, square wave voltammetry and chronoamperometry techniques. Under optimized conditions, the nitroaromatic compounds exhibited reduction peaks corresponding to the number of nitro-functional groups on an aromatic ring. The electrochemical studies revealed that the composite with 7 wt% V2O5 (VOCN7/GCE) exhibits higher sensitivity for the detection of 4-NP, DNP, DNT and TNP. The VOCN7/GCE recorded the limit of detection (LOD) as low as 0.85 nM, 3.3 nM, 3.4 nM and 11.0 nM in a linear range between 1.0 nM - 100.0 µM, 10.0 nM - 100.0 µM, 10.0 nM - 100.0 µM and 30.0 nM - 100.0 µM for 4-NP, DNP, DNT and TNP, respectively. The fabricated sensor showed high reusability and reproducibility, and could detect the four nitroaromatics in real water samples.

Multi-functionalization strategy for environmental monitoring: A metal-organic framework for high capacity Mercury(II) removal and exceptionally sensitive detection of nitroaromatics

The development of multifunctional metal-organic frameworks (MOFs) is a desirable method to use in different applications. As a new 3D MOF decorated with thiophene-urea functions, TMU-57 (formulated as [Zn(TDC)(DPU)].0.85DMF where H2TDC = thiophene-2,5-dicarboxylic acid, DPU = 1,3-di(pyridin-4-yl)urea), has been synthesized to improve the host-guest chemistry of the material. Since, TMU-57 is decorated with electron-rich thiophene and urea functions, it can interact through hydrogen bonding and Lewis acid-base interactions with different guests. In line with this approach, it is realized that TMU-57 is one of the most sensitive sensors to phenolic nitroaromatics (NACs), particularly 2,4,6-trinitrophenol, which reaches 92.5% (9) quenching at 5 ppb with Ksv value equal to 2 (1) × 10+8 M−1 and the detection limit of 9 × 10 −9 M (k = 3, σ = 0.6). Additionally, TMU-57 shows a high capacity for Hg(II) ions equal to 570 (14) mg.g−1. This work clearly shows that the multifunctionalization strategy can extend the application of functional MOFs as an efficient host from one to multiple applications.

A Portable Electrochemical Sensor Based on Manganese Porphyrin-Functionalized Carbon Cloth for Highly Sensitive Detection of Nitroaromatics and Gaseous Phenol.

Organic pollutants (OPs) have garnered a considerable amount of attention in recent times due to their extreme toxicity toward humans and the ecosystem. The need for an inexpensive yet robust, sensitive, selective, and easy-to-operate method for detecting OPs remains a challenge. Herein, a portable electrochemical sensor is proposed based on manganese porphyrin-functionalized carbon cloth (CC). To explain the electrochemical performance of the sensor, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed. The presence of manganese(III) ion in the center of the porphyrin ligand acted as an agent for the transfer of electrons and enhanced sensitivity toward analyte-specific redox catalysis. Moreover, it allowed for the concurrent detection of multiple analytes in a complex environment. The modified CC electrode can selectively detect nitroaromatic and phenolic compounds with accessible data collected through wireless means onto a smartphone device. The as-synthesized electrode demonstrated a higher sensitivity toward the detection of nitrobenzene (NB) and aqueous phenol with a limit of detection (LOD) found to be 5.9268 × 10-10 M and 4.0178 × 10-10 M, respectively. Additionally, our proposed portable electrochemical sensor demonstrates a high selectivity and reproducibility toward nitroaromatic and phenolic compounds, which can be employed in real complex water samples. With regard to the sensor's remarkable electrochemical performance, it is envisaged that such a sensor could pave the way for environmental point of care (POC) testing.

Aggregation Induced Emission (AIE)‐Active Poly(acrylates) for Electrofluorochromic Detection of Nitroaromatic Compounds

AbstractTwo aggregation induced emission (AIE)‐active poly(acrylates) bearing triphenylvinyl‐functionalized phenylcarbazole and triphenylamine pendants, respectively, were synthesized. Their fluorescence response to nitroaromatics and electrofluorochromic (EFC) properties were studied, whereby both the presence of nitroaromatics and applied voltages led to fluorescence quenching. In a very first attempt to perform EFC detection of nitroaromatics, it was surprisingly found that after initial fluorescence quenching, the presence of nitroaromatics unexpectedly turned on fluorescence at high applied voltages (>+1.0 V), demonstrating a promising approach for the EFC detection of nitroaromatic explosives.

Conjugated Polymer Nanoparticles Based on Anthracene and Tetraphenylethene for Nitroaromatics Detection in Aqueous Phase

The sensitive and selective detection of nitroaromatic explosives is of great significance to national security and human health. Herein, the novel linear polymer l-PAnTPE and cross-linked polymer PAnTPE nanoparticles based on anthracene and tetraphenylethene groups were designed and successfully synthesized via Suzuki-miniemulsion polymerization. The particle sizes of the polymers are around 73 nm, making them well dispersible in water. The cross-linked polymer PAnTPE exhibits porous structure, which is beneficial for the diffusion/adsorption of analytes. The fluorescence sensing towards nitroaromatics was performed in the aqueous phase, and l-PAnTPE and PAnTPE nanoparticles showed different quenching degree towards different nitroaromatics. Among them, the quenching constant KSV values of l-PAnTPE and PAnTPE towards 2,4,6-trinitrophenol (TNP) reach 1.8 × 104 M−1 and 4.0 × 104 M−1, respectively, which are 1–2 orders of magnitude higher than other nitroaromatic explosives, thus demonstrating the high sensitivity and selectivity of TNP detection in the aqueous phase. The sensing mechanism was further discussed to clarify this phenomenon by analyzing UV–Vis absorption, excitation, fluorescence spectra, cyclic voltammograms and fluorescence decay measurements. In addition, the paper strips tests exhibit that l-PAnTPE and PAnTPE have great potential in the application of fast, low-cost and on-site nitroaromatics detection.

Importance of the donor unit on fluoranthene for selective detection of nitro aromatic explosives

In this work, two aggregation-induced emission enhancement (AIEE) materials encompassing phenyl (M1) and thiophene (T1) units flanked to fluoranthene were synthesized. We report a new packing polymorphic phase of M1 and the molecular interactions in the crystal lattice were stabilized by CH···π (2.882 Å) interactions. Single crystal X-ray diffraction (SXRD) studies revealed that high torsional angles of phenyl/thiophene unit on the fluoranthene endow weak π-π intermolecular interactions in the crystal lattice. The photophysical properties of M1 and T1 were explored in solution, solid-state and their AIEE phenomenon was studied in THF/water systems. Both the compounds show strong sky-blue emission at 453 nm (M1) and 460 nm (T1). The fluorescence lifetime and quantum yields are varied significantly in the aggregated form. The emission enhancement ascribed due to restricted intramolecular rotation (RIR) of thiophene/phenyl with central π-conjugated fluoranthene in the aggregation state. Distinct changes in the surface morphology, variation in the photophysical properties and energy levels by varying the THF/water ratios furnish its potential towards trace detection of different nitroaromatics. Both materials show high sensitivity and selectivity towards detection of Trinitrophenol (TNP), however, T1 showed a high quenching rate constant at fw = 90 % (KSV = 5.81 × 104 M−1) with LOD of 0.6 ppm at fw = 70 %. The observed fluorescence quenching is attributed due to photoinduced electron transfer from fluoranthene to nitroaromatics through static quenching process. The remarkable efficiency of these fluorescent probes were further explored towards the analysis of river/tap water samples, suggesting their high potential for use in field analysis.

High surface area dendritic silica pairing with anthraquinone derivative: A promising single platform for dual applications of detection and remediation of nitroaromatics and copper ion

The dendritic fibrous nano-silica (DFNS) based functional materials are relatively rare owing to the earlier cognition of DFNS as low surface area bearing material. However, the unique architecture of DFNS is promising for multifunctional payloads if the surface area can be increased. Here, a uniform-sized, high surface area DFNS is synthesized by a modified process using thiourea (NH2CSNH2) for the first time as the hydrolyzing agent. Subsequently, the two relatively unexplored components, DFNS and 1,8-dimorpholinoanthracene-9–10-dione (MORDA), were utilized to derive the functional material (DFNS@MORDA). The above material is used for the dual functions of detection & remediation of nitroaromatics and copper ions from the aqueous solution. A fluorescence resonance energy transfer (FRET) based quenching behavior along with acid-base induced electron transfer process was observed with 4-nitrophenol (4-NP), 2,4,6-trinitrophenol (TNP), 4-nitrocatechol (4-NC), and a coordination complexation driven static quenching was observed with Cu2+ ion with LOD (Limit of detection) values 0.075, 0.010, 0.090, and 0.13 µM respectively. The material adsorbs the above analytes with maximum adsorption capacities of 450, 540, 556, and 398 mg g−1 and is recycled easily. This material as a fluorescence probe was used for quantification of copper in actual samples very precisely. Thus, the functional material is a rare example of fluorescent probe cum adsorbent material for nitroaromatics and copper ion.

Fabrication and photophysical assessment of quinoxaline based chemosensor: Selective determination of picric acid in hydrogel and aqueous medium

The design and development of innovative chemosensor probes for the detection of trace nitroaromatics is crucial due to its detrimental effect on human health and the environment. In this regard, an electron-rich amino incorporated quinoxaline probe (L1) was synthesized, which unveiled a highly discriminative fluorescence turn-off response towards picric acid (PA) with a 5.21 ppm detection limit (KSV ~20.87 × 106 M−1). Detailed spectroscopic and DFT studies validated that PET from electron-rich L1 to electron-deficient PA was responsible for fluorescence quenching. The probe was also incorporated into a natural, guar gum-based polymeric hydrogel matrix to develop a smart, portable fluorescent hydrogel-based sensor. It also displayed similar fluorescence quenching responses (LOD 9.45 ppm). Morphological and rheological characterization studies further validated the stability and efficacy of the fluorescent hydrogel. The practical viability of the chemosensor was further explored effectively in natural groundwater samples and the vapor phase.

Co2+ and nitrobenzene sensing using indium-based metal-organic framework

A highly stable indium-based metal-organic framework, namely [In(HTCA)(OH)]·2DMF·H2O (JOU-24), was solvothermally synthesized by using fluorescent ligand H3TCA (H3TCA = 4,4′,4″-tricarboxytriphenylamine). Single-crystal X-ray diffraction analyses show that JOU-24 displays two-dimensional framework based on infinite straight In-O-In chains. Further studies show that JOU-24 can keep its stability in water with pH range from 1 to 11. Thereafter, JOU-24 was developed as an excellent fluorescence sensor for selective detection of Co2+ and nitrobenzene (NB) in water due to its good fluorescence performance. For Co2+ sensing, a high quenching content is determined to be 24,500 with a low determine limit of 4.9 × 10−6 mol/L. For NB sensing, quenching content is 10230, which is also comparable to other reported MOFs. In addition, the mechanism for Co2+ and NB sensing is also proposed. This work shows a simple method to construct high-efficient fluorescence sensor for metal ions and nitroaromatics detection.

Efficient nitro-aromatic sensor via highly luminescent Zn-based metal-organic frameworks

Highly stable zinc-based luminescent metal-organic framework (LMOF) [(Zn2-(NDC)2(bpy)·Gx) where NDC-2,6-naphthalene dicarboxylic acid, bpy - 4,4' bipyridine, and G - guest solvent molecules] is synthesized via solvothermal method at different synthesizing temperatures (120, 150 and 180∘C) for the detection of nitro-aromatics. Sample structure and presence of ligands is confirmed by X-ray diffraction and FTIR measurements, respectively. The photoluminescence properties of synthesized LMOF samples show the strong emission intensity in ethanol at 376 nm when it is excited at 240 nm. The detection limit is calculated using fluorescence quenching for the various nitro-analytes (2,4-DNP, 2-Nitrotoulene, 4-Nitrophenol, and Nitrobenzene) revealed that it is least for the sample synthesized at 150∘C with the maximum percentage in fluorescence decay. The thermal stability of as-synthesized samples is analysed using thermogravimetry analysis (TGA) which reveals that sample synthesized at 150∘C is the most stable sample. The TGA analysis also shows that on further heating from 526∘C to 980∘C decomposition of zinc metal and formation of zinc oxide takes place. FE-SEM confirms the cuboidal morphology with an average particle size of 12.62 nm, corroborated by the TEM analysis. The fluorescence quenching mechanism is explained on the basis of dipole-dipole and π-stacked interactions between the MOF and nitro-aromatics that play a prominent role in the sensing of nitro-analytes. Synthesized MOF samples show excellent recyclability in fluorescence quenching even after the fourth cycle, i.e. more than 95% and is sensitive to detect nitro-aromatics even upto 0.284 µM, and the results can generalize the explosive sensor technology and sensing various nitro-based pollutants.