Detection Of Nitroaromatic Explosives Research Articles

A “turn-off” fluorescent sensor based on electrospun polycaprolactone nanofibers and fluorene(bisthiophene) derivative for nitroaromatic explosive detection

The preparation of fluorene(bisthiophene)-based fluorescent nanofibers for nitroaromatic explosive detection provides a convenient rapid and low-cost strategy aiming at forensic applications. Polycaprolactone (PCL) and fluorene(bisthiophene) derivative (FBT) nanofibers were obtained by electrospinning technique as a free-standing mat and characterized by SEM, FTIR, thermal analysis and fluorescence spectroscopy. The PCL/FBT nanofibers presented high sensitivity towards 2,4,6-trinitrotoluene (TNT) and picric acid (PA), with fluorescence quenching (turn-off mechanism), and selectivity to another kind of explosives. The free-standing mats were used as a cloth strip that was swiped on surfaces contaminated with TNT traces allowing its visual detection under UV light source. These findings are particularly important for the development of a facile and promising strategy to assembly portable optical devices for nitroaromatic explosive detection.

Synthesis of Copper Metal Organic Framework Based on Schiff Base Tricarboxylate Ligand for Highly Selective and Sensitive Detection of 2,4,6-Trinitrophenol in Aqueous Medium.

By using Schiff base tricarboxylate ligand 5-(4-carboxybenzylideneamino)isophthalic acid (H3CIP), a new imine functionalized copper metal organic framework (MOF) has been synthesized solvothermally. It was 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. The as-synthesized MOF has been utilized as fluorescent probe for detection of nitro aromatic explosives (NAEs). The results show that the copper MOF can be developed into highly selective and sensitive sensor for detection of TNP in the aqueous medium via the "turn-off" quenching response. The linear fitting of the Stern-Volmer plot for TNP offered large quenching constant of 1.07 × 104 M-1 for Cu-MOF indicating the high sensitivity of the sensing process. Outstanding sensitivity of prepared material towards TNP detection was further validated by the low detection limit of 80 ppb (0.35 µM). The detailed mechanistic studies for their mode of action and density functional theory (DFT) calculations reveals that photo-induced electron transfer (PET) and fluorescence resonance energy transfer (FRET) processes, as well as electrostatic interactions (i.e. H-bonding) are the key factors for the turn-off response toward TNP by this fluorescent sensor. Thus, this new LMOF owing to their high water stability and remarkable functional features are potential candidates which can be developed into selective and sensitive TNP detection devices.

A {Zn5} cluster‐based metal–organic framework: Multifunctional detection of Ag+, Cr2O72−, and 2,4,6‐trinitrophenol (TNP)

AbstractIt is important to develop sensors that can be easily fabricated for the detection of harmful industrial wastes and nitroaromatic explosives to reduce the risks to human health and protect the environment. We report a new luminescent metal–organic framework (MOF), [Zn5(μ3‐OH)2(TDA)4(4,4′‐bpt)2]n (1), (4,4′‐bpt = 1H‐3,5‐bis‐(4‐pyridyl)‐1,2,4‐triazole, H2TDA = thiophene‐2,5‐dicarboxylic acid), which was synthesized under solvothermal conditions and characterized using the PXRD, IR, TG, ICP‐MS, mapping, and PL spectroscopic techniques. The {Zn5} MOF of (1) with Zn5 cluster as the node, and 4,4′‐bpt and TDA2− as linkers, exhibited excellent thermal and chemical stabilities. Furthermore, 1 can serve as a sensitive and recyclable luminescent probe for the detection of Ag+, Cr2O72−, and TNP with detection limits of 5.96, 4.34, and 1.59 μM, respectively.

Polyfluorene based fluorescent sensor for sensitive and selective detection of picric acid

A novel conjugated polyfluorene derivative (PCFSe) was successfully synthesized, with benzo[c][1,2,5]selenadiazole in polyfluorene backbone and N-alkylcarbazole in the side chain. PCFSe shows an orange-red fluorescence emission at 570 nm with a high glass transition temperature and excellent thermal stability. In the fluorescence titration experiments, PCFSe as fluorescent sensor exhibits varying degrees of fluorescence quenching towards different nitroaromatics, in which picric acid (PA) detection has the highest sensitive response with the Stern-Volmer quenching constant KSV value of 1.2 × 104 M−1 and the calculated detection limit of 0.27 ppm. Meanwhile, the quenching effect of PA to PCFSe has no significant change even in the presence of other nitroaromatics, indicating a selective PA detection. Furthermore, the paper strips were also fabricated to detect PA, achieving a practical application in fast, easy and on-site detection of nitroaromatic explosives.

Chemiresistive Device for the Detection of Nitroaromatic Explosives Based on Colloidal PbS Quantum Dots

Semiconductor quantum dots have been recently employed as luminescent probes for the detection of hazardous nitroaromatic compounds. Despite the high sensitivity, such detection systems involve laboratory procedures and employ complex instrumentation. Here, we demonstrate the use of colloidal PbS quantum dots as the main component of a chemiresistor for the detection of nitroaromatic compounds. The proposed device is low-cost, reusable, and produces an electric signal that can be acquired with off-the-shelf electronic components. In this paper, we demonstrate the operation of the proposed device and we discuss its sensing mechanism. We also show the sensor’s response to nitrobenzene in the 65 ppb–16 ppm range, estimating a theoretical detection limit of 2 ppb.

Aggregation-induced emission-active hyperbranched polymers conjugated with tetraphenylethylene for nitroaromatic explosive detection

This work develops a facile synthesis for aggregation-induced emission (AIE)-active hyperbranched polyglycidols (HPGs) to design a solid-state sensor for detecting nitroaromatic explosives. The tetraphenylethylene moieties were conjugated onto the periphery of the HPGs in a single step using dynamic boronate ester cross-linkers. The resulting AIE-active HPGs exhibited excellent AIE characteristics in tetrahydrofuran (THF)/H2O mixtures, emitting a strong blue fluorescence under UV irradiation. Dynamic light scattering and transmission electron microscopic analyses demonstrated that the self-assembled nanosized aggregates were stable in the THF/H2O mixture. The fluorescence of the aggregates was dramatically quenched by various nitro compounds, including 2,4,6-trinitrophenol (or picric acid; PA), 2,6-dinitrophenol, 4-nitrophenol, 4-nitrotoluene, and nitromethane. The nano-aggregates exhibited extraordinary sensitivity towards PA, with a Stern‒Volmer constant (Ksv) of 2.27 × 104 M−1 and a limit of detection of 40 ppb. Paper strips encapsulating the aggregates exhibited a vivid visual quenching, promising the practical applicability of these polymers as solid-state sensors for the detection of nitroaromatic explosives.

A Simple Determination of Trinitrotoluene (TNT) Based on Fluorescence Quenching of Rhodamine 110 with FRET Mechanism.

Sensitive and selective detection of nitroaromatic explosives is an important issue in regard to human health, environment, public security and military issues. In this study, a simple and sensitive fluorescence quenching - based assay utilizing Rhodamine 110 as fluorophore probe was developed for the determination of trinitrotoluene (TNT). This sensitive fluorometric method could measure the decrease in fluorescence of Rhodamine 110 (λex = 490nm, λem = 521nm) owing to the primary amine groups of Rhodamine 110 (different from other rhodamines) capable of donor-acceptor interaction with TNT. The resulting TNT-amine complex can strongly quench the fluorescence emission of Rhodamine 110 by fluorescence resonance energy transfer (FRET) which occurs as the excited Rhodamine 110 fluorophore (donor) transfers its energy to TNT (acceptor) by non-radiative dipole-dipole interaction. Fluorescence quenching varied linearly with TNT concentration, with LOD and the LOQ of 0.71 and 2.38mg L- 1 TNT, respectively. Similar explosives, common soil ions, and possible camouflage materials were found not to interfere with the proposed method, offering significant advantages with its easy methodology, low-cost, sensitivity, and rapidity of analysis. FRET mechanism based on dye donor-TNT acceptor interaction.

Bifunctional Sr(II)‐terephthalate compound: gas adsorption and luminescence sensing properties

AbstractA new thermostable Sr(II) compound, formulated as [Sr(bdc)(H2O)(DMF)]n ⋅ x(solvent) (1, H2bdc=terephthalic acid, DMF=N,N’‐dimethylformamide), has been synthesized from the solvothermal reaction of Sr(NO3)2 and H2bdc. The X‐ray structural analysis revealed that compound 1 features a 3D framework based on 1D Sr(II)‐carboxylate chains, and the coordinated and free solvent molecules filled in the 1D channels of 1, which can be easily removed from the 3D framework via heat treatment activation. The obtained solvent‐free samples 1 a not only shows high adsorption capacities of C2H2 and CO2 at 298 K, moderate adsorption selectivity for C2H2/CH4, CO2/CH4, but also can be used as a luminescent probe for the detection of nitroaromatic explosives.

Highly cross-linked polymeric nanoparticles with aggregation-induced emission for sensitive and recyclable explosive detection

Aggregation-induced emission (AIE) polymeric nanoparticles (PNPs) are promising candidates for detection of nitroaromatic explosives. However, the major limitation of these AIE PNPs is the complicated synthesis and deteriorated detection accuracy because of the poor colloidal and morphological stability. This study provided a facile method to construct AIE PNPs with highly cross-linked polymer matrix for sensitive and accurate detection of nitroaromatic explosives. The highly cross-linked AIE PNPs with a ~50 nm particle size were prepared through copolymerization of divinylbenzene (DVB) and a tetraphenylethene (TPE)-based AIE luminogen, (4′-tetraphenyletheyl)pheny-3-butenylether (TPE-PBE), in a water-borne miniemulsion system. Due to the good aqueous dispersibility and highly cross-linked polymer matrix, the poly(DVB-co-TPE-PBE) NPs showed excellent solvent resistance, and sensitive and accurate detection of nitroaromatic explosives in aqueous systems, especially picric acid (PA). Moreover, a rigid poly(DVB-co-TPE-PBE) film could preserve spherical morphology after coating poly(DVB-co-TPE-PBE) NPs onto various substrates (such as filter paper and glass slide). The high surface area and loose packing of poly(DVB-co-TPE-PBE) NPs offered convenience for 2,4-dinitrotoluene to diffuse and interact with TPE-PBE units. Therefore, cost-efficient and portable poly(DVB-co-TPE-PBE)-coated test strips and film on glass slides exhibited fast response, strong quenching ability, and reusability in visual detection of liquid and volatile explosives, respectively.

Multi-functional lanthanide coordination polymers for multi-modal detection of nitroaromatics and trace water in organic solvents

Multifunctional materials used for multimodal sensors are of great significance both for enriching variety of materials and overcoming the shortcomings of traditional single signal sensors. This work reports the ultrafast preparation of multifunctional coordination polymer (CP) spheres with metalloligand Ru (II)[4,4′-(COOH)2-bpy]3▪Cl2 (L) and Gd3+ ions. Gd-L CPs were used for multi-modal detection of nitroaromatic explosives and trace water in organic solvents with their red fluorescence and magnetic resonance response. The red fluorescence was derived from the ligand, which is electron-rich because of the bipyridine rings. There were different emission behaviors when Gd-L CPs reacted with nitroaromatic explosives that have various electron-deficient properties through electron transfer donor–acceptor mechanism. The changes in the emission depended closely on the nitroaromatic explosives ability to withdraw electrons. Gd-L CPs also showed magnetic resonance response with r1 of 12.1 mM−1s−1 due to the integration of the paramagnetic property of Gd3+ ions. Smart sensing of trace water in organic solvents was achieved by magnetic signals. The fluorescence of Gd-L CPs was enhanced and there was a tiny blue-shift in protonic solvents with increased polarity. The fluorescence sensor used in detecting trace water had a consistent result like the MR response. Thus, Gd-L CPs enabled the use of fluorescence and magnetic resonance sensors simultaneously for the first time to overcome the shortcoming of single modal sensor and expand the application of magnetic resonance relaxation.

Si-doped graphene nanosheets as a metal-free catalyst for electrochemical detection of nitroaromatic explosives

Si-doped graphene nanosheets (SiGNS) have been successfully constructed via high temperature annealing of graphene oxide and tetraethoxysilane mixture in a sealed glass ampoule. The Si atoms doped into graphene’s carbon network mainly existed as C3-Si-O and C2-Si-O2 configurations. The as-prepared SiGNS exhibited excellent electrochemical detection ability to nitroaromatic compounds in 0.1 M phosphoric acid buffer solution (PBS, pH = 8.0) via an electrochemical catalytic process. Five nitroaromatic compounds, including nitrobenzene, 2-nitrotoluene, 4-nitrotoluene, 2, 4-dinitrotoluene and 2, 4, 6-trinitrotoluene, were taken as the analyte to demonstrate the electrochemical catalytic ability of SiGNS. Density functional theory (DFT) calculation was carried out to explore the electrochemical catalytic mechanism of SiGNS. A hydrogen bond mediated electrochemical catalytic mechanism was proposed. Both the excellent electrical conductivity and the rich surface hydroxyl groups enhanced the electrochemical detection ability of SiGNS to nitroaromatic compounds. Si atoms in SiGNS played a key role for the excellent electrochemical detection ability of SiGNS due to most of the surface hydroxyl groups anchored on the Si atoms.

Tetraphenylethene probe based fluorescent silica nanoparticles for the selective detection of nitroaromatic explosives.

A simple and sensitive fluorometric method is developed utilizing aggregation-induced emission probe based silica nanoparticles for the detection of nitroaromatic explosives. A positively charged tetraphenylethene based probe (TPE-C2-2+) is doped into silica nanoparticles exploiting electrostatic interactions to produce TPE-SiO2 nanoparticles with a uniform particle size. The TPE-SiO2 nanoparticles exhibit strong fluorescence emission due to the aggregation-induced emission (AIE) effect of the doped TPE probe. The fluorescence emission of TPE-SiO2 offers quantitative and sensitive response to picric acid (PA), 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) which are used as model examples of nitroaromatic compounds. The fluorescence spectroscopy results show that the fluorescence emission of TPE-SiO2 was greatly quenched in the presence of the electron-poor nitroaromatic compounds due to the inner filter effect (IFE) and possibly the contact quenching mechanism. TPE-SiO2 nanoparticles show better sensitivity towards PA and could detect PA down to 0.01 μM with a linear detection range of 0.1-50 μM. The increased chemical stability, efficient high sensitivity and simple synthesis of the TPE-SiO2 nanoparticles demonstrate that they can be used as an excellent fluorescent probe for a wide range of electron-poor compounds, i.e. nitroaromatic compounds. Interference studies show that common interfering species with nitroexplosives such as acids, bases, volatile organic compounds, and salt solutions have a negligible effect during the sensing process.

A luminescent metal–organic framework with tetragonal nanochannels as an efficient chemosensor for nitroaromatic explosives detection

A 3D MOF with nanosized channels can act as an effective fluorescence probe, showing obvious fluorescence “turn-off” for nitroaromatic explosives.

Detection of Trace-Level Nitroaromatic Explosives by 1-Pyreneiodide-Ligated Luminescent Gold Nanostructures and Their Forensic Applications.

By attaching the1-pyreneiodide ancillary ligand to the surface of polyvinylpyrrolidone-stabilized gold (Au:PVP) cluster or the cetyltrimethyl ammonium bromide-stabilized gold (Au:CTAB) nanorod, a new class of luminescent mixed ligand-stabilized gold nanostructures is synthesized. This postsynthetic surface modification method followed by us is a comparatively easier and hassle-free technique to acquire surface-active luminescent "functional nanomaterials". Careful analyses of transmission electron microscopy images revealed that the sizes of these Au-clusters or Au-nanorods remain unchanged without any noticeable aggregation in the medium. Owing to the formation of an excimer within the neighboring pyrenes mounted on the surface of core nanostructures (i.e., Au:PVP nanocluster and Au:CTAB nanorod), the resulting pyrene-grafted nanocomposites exhibit strong emission characteristics. The strong excimer emission is significantly quenched in the presence of electron-deficient chemical inputs, and this phenomenon can be used for analytical purposes. Using these luminescent Au-nanomaterials, we demonstrate a selective detection and sensing of trace-level nitroaromatic explosives (e.g., trinitrotoluene, trinitrophenol (TNP), dinitrotoluene, 4-nitrotoluene, etc.). It was observed that the Py-Au:PVP nanocluster is equally effective for explosive detection in both solution and solid phases with the limit of detection up to 10 nanomolar. A high Stern-Volmer constant of up to 3.88 × 106 M-1 was seen in the case of TNP in anhydrous methanol at 298 K. The deactivation pathway operating within the Py-Au:PVP nanocluster and the analytes is thought to be a result of a predominating static quenching process, where a nonfluorescent D-A supramolecular adduct is formed in the medium. Py-Au:PVP has also been successfully used to develop latent fingerprints from nonporous surfaces under an exposure of 365 nm UV light. The results suggest that these new composite materials could behave as potential "functional nanomaterials", which might be a promising alternative for on-the-spot detection of explosive traces as well as for easy visualization of latent fingerprints.

Synthesis, characterization and density functional theory of copper(II) complex and cobalt(II) coordination polymer for detection of nitroaromatic explosives

In recent years there has been a significant interest to design luminescent materials to detect explosives with a great degree of selectivity, sensitivity, and fast response time. Two new luminescent compounds, [Cu(Biphen)(Meim)(H2O)] 1 and [Co(BDC)(Meim)2]n2 (where HBiphen = biphenyl-4-carboxylic acid, H2BDC = 1,4-benzenedicarboxylic acid and Meim = 1-methylimidazole) were synthesized under solvothermal and reflux conditions. The compounds were characterized by elemental analysis, FT-IR, thermogravimetric analysis, and electronic spectroscopy. Single Crystal X-ray Diffraction (SC-XRD) was used to determine their crystal structures. 1 crystallizes in the monoclinic space group I2/a, and the geometry around the metal center is square pyramidal connected by two (μ-N)2 of Meim and two (μ-O)2 of Biphen and a coordinated water molecule. 2 exhibits tetrahedral geometry connected by two (μ-N)2 of Meim and two (μ-O)2 halves of BDC in the triclinic space group P-1. Photophysical properties of the solid-state complexes were analyzed using fluorescence spectroscopy. 1 displayed high emissions at 430 nm (λex = 264 nm) and 2 at 384 nm (λex = 265 nm) which could be assigned to ligand to metal charge transfer (LMCT) due to the ligand's extended π-conjugation. Compounds 1 and 2 display selective nitroaromatic quenching response over other organic molecules having detection limits ranging between 1.66 ppm and 13.07 ppm, respectively. Density Functional Theory (DFT) revealed that potential interactions leading to the formation of adducts result from the transfer of electrons by hydrogen bonding and π-π stacking. Compound 2 was found to have greater ability to quench nitro analytes.

Hyper-crosslinked 4-amino-1,8-naphthalimide Tröger’s base containing pyridinium covalent organic polymer (COP) for discriminative fluorescent sensing of chemical explosives

ABSTRACT A new hyper-crosslinked 4-amino-1,8-naphthalimide Tröger’s base containing pyridinium covalent organic polymer, TBNap-COP, was synthesised and employed as a ‘turn-off’ fluorescent chemosensor for nitroaromatic explosives. TBNap-COP was synthesised in quantitative yield using a one-step nucleophilic substitution reaction between a dipyridyl scaffold (TBNap, bis-[N-(2-(pyridine-4-yl)ethyl)]-9,18-methano-1,8-naphthalimide-[b,f][1,5]diazocine) and 1,3,5-tris(bromomethyl)benzene by heating in DMF for 3 days. The formation and phase-purity of TBNap-COP were fully characterised by using various spectroscopic and microscopy analyses. The suspension of TBNap-COP in water showed strong fluorescence emission characteristics owing to the ‘push-pull’ based ICT transition and it was used as a fluorescent sensor for discriminative detection of nitroaromatic explosives. TBNap-COP displayed selective fluorescence quenching responses for phenolic-nitroaromatics, with particularly high sensitivity for picric acid which is a powerful secondary chemical explosive and a harmful environmental pollutant widely used in the dye industries.

Magnetically Separable Fe3O4@Au@Tb‐MOF Fluorescent Probe with Well‐Designed Sandwich Structure and Metal‐Enhanced Fluorescence

AbstractExploiting a high‐performance magnetic separation probe is important for the detection of nitroaromatic compounds. Here, a novel Fe3O4@Au@Tb‐BTC metal–organic framework (MOF) fluorescent probe was synthesized and used for the determination of nitroaromatic hydrocarbons. Thanks to the fluorescence enhancement of the gold nanoparticle‐layer and the sheet structure of the outer Tb‐BTC, the Fe3O4@Au@Tb‐BTC with sandwich structure exhibits significantly higher sensitivity than Fe3O4@Tb‐BTC in quantitative detection of nitroaromatic explosives. The quenching constant (Ksv) toward picric acid in ethanol is up to 5.08×104 M−1 and the limit of detection (LOD) could reach to 3.14×10−6 M. Furthermore, it can be easily to recycle by applying an external magnetic field. The unique sandwich structure makes Fe3O4@Au@Tb‐MOF highly efficient and recoverable, offering broad opportunities in the field of promising probe synthesis and application.

Highly sensitive and ultrafast film sensor based on polyethyleneimine-capped quantum dots for trinitrophenol visual detection.

Real-time detection of nitroaromatic explosives is a pressing problem for public security and environmental monitoring. Although many efforts have been devoted, sensing of explosives still suffers limitations of complicated and time-consuming sensing procedure. In this work, we develop a fluorescent film for rapid and visual detection of 2,4,6-trinitrophenol (TNP) by using polyethyleneimine-capped quantum dots (QDs-PEI) as fluorescent sensing probe and electrospun membrane as matrix. Fluorescent sensing is mainly based on effective reaction between amino groups of PEI and nitro groups, phenol hydroxyl groups of TNP. It also benefits from the rapid absorption of TNP in aqueous solution by PA6 nanofiber membranes with high hydrophilicity and porosity. As a result, visual sensing could be realized when TNP is >100ng·mL-1 by obvious fluorescent change with a thirty-second response time. We believe this fluorescent membrane sensor holds a promising prospect for real time and visual detection of TNP in environmental science and analytical fields.

Surfactant-assisted synthesis of fluorescent SmCrO3 nanopowder and its application for fast detection of nitroaromatic and nitramine explosives in solution

In this work, SmCrO3 nanopowder was synthesized via sol gel route assisted by citric acid and cetyltrimethylammonium bromide (CTAB) in water. The obtained SmCrO3 perovskite oxide nanopowder exhibits strong fluorescence at near-UV and visible regions in polar solvents such as ethyl acetate (EtOAc), tetrahydrofuran (THF) and ethyl methyl ketone (EMK) that its fluorescence could be strongly quenched by nitro explosives such as TNP, TNT, HMX and RDX at room temperature. Thus, the prepared fluorescent nanopowder was used as chemosensor for selective detection of nitro explosives. The lowest detection limit (6.0 × 10−8 M) was observed for HMX and the highest detection limit (9.6 × 10−7 M) was obtained for TNP in THF solvent. The obtained results confirm that the quenching effect of the nitro explosives on the fluorescence signal of the SmCrO3 nanopowder can be take place fluorescence resonance energy transfer (FRET) mechanism. This rare earth orthochromite based perovskite will introduce a new group of inorganic compounds that potentially can be effective for rapid and sensitive sensing for trace value of the nitro explosives. In addition, due to great chemical and thermal stability of chromite perovskite structures, these chemosensors can be easily recovered.

Poly-tryptophan/carbazole based FRET-system for sensitive detection of nitroaromatic explosives

Sensitive detection of nitroaromatic explosives, a hot topic of worldwide concern, is greatly asked for, due to the adverse effect on ecosystems and human health originating from the excessive use and inadequate management. Here, we report the development of a Förster Resonance Energy Transfer (FRET) based sensor system for highly sensitive detection of nitro-aromatic compounds (NACs). The sensor system is composed of a copolymer poly[(N,N-dimethylacrylamide)-co-(Boc-Trp-EMA)] (RP) bearing tryptophan derivative in the side chain as donor and carbazole (CZ) as an acceptor. Primarily, the fluorescence of RP copolymer is quenched by non-radiative energy transfer to CZ which only happens once the two molecules are within Förster critical distance. The efficiency and rate of energy transfer process were calculated for this deliberated FRET system. This FRET pair exhibited a specific fluorescence response to NACs such as 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) with 6.4, 5.9 and 1.4 μM limit of detections (LODs), respectively. Interestingly, the order of sensitivities of the FRET pair to NACs was very high. The sensing process occurs through a static and dynamic quenching pathway, confirmed by Stern−Volmer analysis of steady-state and time-resolved fluorescence as well as UV–Vis Spectroscopy.