Detection Of Nitroaromatics Research Articles

Detection of Nitroaromatics by Pyrene-Labeled Starch Nanoparticles

Starch nanoparticles (SNPs) were hydrophobically modified by using 1-pyrenebutyric acid (PyBA) with degrees of substitution (DS) between 0.0006 and 0.11. Fluorescence quenching studies were conducted on the pyrene-labeled starch nanoparticles (Py-SNPs) in dimethyl sulfoxide (DMSO) and water with nitromethane (NM), 4-mononitrotoluene (MNT), 2,6-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) to assess the mode of quenching of the pyrene labels in the two solvents. In DMSO where pyrene, starch, and the quenchers were soluble, a decrease in fluorescence signal was the result of dynamic encounters between the excited pyrene labels and the nitrated quenchers. In water where starch could be dispersed but pyrene and the nitroaromatic compounds (NACs) were sparingly soluble, quenching took place through the binding of NACs to pyrene aggregates. Py(11)-SNPs (Py-SNPs with a DS of 0.11)-coated filter papers (Py-CFPs) were prepared as fluorescence sensors. The fluorescence emitted by Py-CFPs was quenched to 25% of its original value within 10 ± 2, 72 ± 20, and 23 ± 4 s upon exposure to vapors of MNT, DNT, and TNT, respectively. When known amounts of NACs were deposited onto Py-CFPs, their limit of detection (LOD) when the fluorescence decreased by more than 3 standard deviations (3σ) from its original value equaled 9.2 ± 0.8, 3.3 ± 0.5, and 0.20 ± 0.02 ng/mm2 for MNT, DNT, and TNT, respectively. These response times and LODs were among the best values reported to date in the scientific literature for fluorescence sensors. The selectivity of the Py-CFPs toward NACs was also investigated by comparing their response to the presence of non-nitrated aromatics, amines, and aromatic ketones. Quenching was only observed with the latter family of chemicals tested, but with much lower efficiency compared to TNT, thus reflecting some level of selectivity toward this specific NAC.

Sensing of Zn(II) and nitroaromatics using salicyclaldehyde conjugated lysozyme-stabilized fluorescent gold nanoclusters

This manuscript presents new applications of the red-emitting lysozyme-stabilized gold nanoclusters (Lyso-AuNCs) in the field of fluorescent sensing. With the addition of salicylaldehyde (SA) to the solution of Lyso-AuNCs, the red-emission turned immediately to yellow, and the emission band at 650 nm was blue-shifted and enhanced significantly at 498 nm due to the formation of imine linkage between the –CHO group of SA and the –NH2 groups of the lysozyme coated on the surface of AuNCs. The nano-assembly SA conjugated Lyso-AuNCs (SA_Lyso-AuNCs) was applied as a nanoprobe for the fluorescent detection of metal ions and nitroaromatics. With the addition of Zn2+, the probe SA_Lyso-AuNCs showed selective turn-on fluorescence enhancement at 452 nm due to the complexation-induced aggregation of the nanoclusters, and the titration experiment inferred that the Zn2+ ions can be detected down to 1.37 × 10−7 M. In contrast, when the nitroaromatics were added to the probe SA_Lyso-AuNCs, selective fluorescence quenching of the probe was observed at 650 nm and 498 nm in the presence of picric acid (PA) and para-nitrophenol (p-NP). The limit of detection of nitroaromatics PA and p-NP can be detected down to 2.90 × 10−7 M and 3.59 × 10−7 M, respectively. Finally, the practical utility of the probe SA_Lyso-AuNCs was validated by quantifying PA and p-NP in the real water samples.

A novel fluorescent triazole trindane-coumarin receptor for the selective detection of nitroaromatics

A new fluorescent triazole trindane-coumarin based chemosensor (L1) was designed, synthesized by click chemistry and applied for the detection of various nitroaromatic compounds, such as 1-chloro-4-nitrobenzene, 4-nitrotoluene, 3-nitrotoluene, m-dinitrobenzene, nitrobenzene, 2-nitrotoluene and 1-chloro-2-nitrobenzene, picric acid and p-nitrophenol. Among the tested nitroaromatics, L1 shows selective turn-off fluorescence in the presence of picric acid and p-nitrophenol due to the energy transfer mechanism in aqueous DMSO medium. Without any noticeable interference from the other tested nitroaromatics, sensor L1 can be applied to detect picric acid and p-nitrophenol down to micromolar range. Further, the practical utility of L1 was validated by monitoring the concentrations of picric acid and p-nitrophenol in the real environmental water samples.

Detection of nitroaromatics in aqueous media based on luminescence resonance energy transfer using upconversion nanoparticles as energy donors

Upconversion nanoparticle (UCNP)-based luminescence resonance energy transfer (LRET) systems are a powerful tool widely used to detect organic molecules or metal ions because of their simplicity and high sensitivity. The sandwich structure NaYF4:Er3+,Yb3+@NaYF4@NH2 UCNPs, as a highly selective and sensitive aqueous probe for detecting nitroaromatics, has been designed and prepared by a cothermolysis method and modified with polyetherimide to acquire amine groups on the surface of the core/shell UCNPs. The detection principle of nitroaromatics is based on LRET, which forms the Meisnheimer complex between the electron-deficient cyclobenzene of nitroaromatics and the electron-rich amino group on the surface of the sandwich structure UCNPs. As a consequence, nitroaromatics can be brought into close proximity to the sandwich structure UCNPs. With the increase of nitroaromatics (2,4,6-trinitrophenol and 2,4,6-trinitrotoluene) concentrations, the sandwich structure NaYF4:Er3+,Yb3+@NaYF4@NH2 UCNPs display a dramatic luminescent quenching effect at 407 nm and 540 nm under 980 nm excitation. The luminescent quenching intensity of the sandwich structure UCNPs is linearly correlated to the concentration of the nitroaromatics. The detection limit of 2,4,6-trinitrophenol (TNP) and 2,4,6-trinitrotoluene (TNT) are 0.78 and 0.77 ng ml−1, respectively. Therefore, the sandwich structure of NaYF4:Er3+,Yb3+@NaYF4@NH2 UCNPs can act as a valuable probe to detect nitroaromatics in public safety and security conditions.

Detection of nitroaromatics based on aggregation induced emission of barbituric acid derivatives.

Barbituric acid derivatives with typical aggregation induced emission (AIE) are reported. Their emission wavelengths varied with water fraction of their solution. UV-visible absorption spectroscopy and theoretical calculations revealed the intramolecular charge transfer (ICT) possibility from donor to acceptor and the mechanism was confirmed as a restriction of intramolecular motion (RIM). The AIE properties were affected by the different substituents on barbituric acid. When the molecular volume increased, the AIE effect decreased. Fluorescent quenching mechanism was applied to detect nitroaromatic explosives. For 2,4,6-trinitrophenol (PA), one of the derivatives 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid in THF/H2O mixture (1:9, v/v), showed amplified fluorescence quenching with a maximum Stern-Volmer quenching constant of 4.1 × 104 M-1. The solid phase paper test based on 5-(4-diphenylamino styrene)-1,3-diphenyl-barbituric acid also showed a superior sensitivity toward PA both in vapor and solution.

Exploring the sensing behavior in the detection of nitroaromatics using coordination complexes based on 4,4′-(1,3-phenylenedioxy)-dianiline ligand

The aromatic ligand 4,4′-(1,3-phenylenedioxy)-dianiline (L), has been used to explore its coordination chemistry behaviour and nitroaromatic sensing ability by crystallizing it with a variety of transition metals. The supramolecular structures [CuCl2(L)] (1), [Mn(H2O)2Cl2(L)2] (2), [Ni(H2O)2 (L)2] Cl2 (3) and [Co(H2O)2 (L)2] Cl2 (4) have been characterized by single crystal X-ray diffraction (SC-XRD) and X-ray powder diffraction (XRPD) analysis. While 1 and 2 do not form polymeric structures but discrete (0D) arrays, 3 and 4 resulted in extended isostructural 2D coordination polymers. The solid-state fluorescence properties of the reported crystals have been investigated. Interestingly, coordination polymers 3 and 4 showed a better solid-state fluorescence emission compared to that of complexes 1 and 2. Coordination polymer 3 has been successfully used as a sensor for the detection of trace amounts of nitrobenzene, 2-nitrotoluene and 3-nitrotoluene with a high quenching efficiency of 96% for 3-nitrotoluene. The quenching efficiency of 3 is better than that of the free ligand L. The polymeric nature of 3 is maintained after the sensing experiment and thus can be used in a recyclable manner. Due to the fact that 3 is a nonporous and its structure does not change in the presence of the quenchers, the quenching effect occurs in the surface of the solids when is in a suspension.

Determination and identification of nitroaromatic explosives by a double-emitter sensor array

Detection of nitroaromatic explosives is of strong concern because of human health, public safety, environment, and military issues. In this study, we present a ratiometric sensor array for detection and discrimination of widely-used nitroaromatics (i.e., 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), and 2,4-dinitrotoluene (DNT)). In the design of sensor elements (SE) we employ blue emissive carbon dots (BCDs) in combination with yellow (SE-A) and red (SE-B) emissive cadmium telluride quantum dots (CdTe QDs). The fluorescence intensity of BCDs, YQDs, and RQDs is quenched by TNT, DNT, and TNP in various degrees. Both TNT and TNP cause the quenching and spectral shift of BCDs (TNT causes a blueshift and TNP causes a redshift). However, DNT has no effect on CDs emission. The developed double-emitter sensor array is capable of discriminating nitroaromatics in the concentration range of 5.0–200.0 μmol L−1 with a limit of quantification as low as 5.0 μmol L−1. In addition, the sensor array demonstrates a promising capacity to detect structurally similar nitroaromatics in mixtures and complex media of soil and groundwater samples.

Influence of alkyl chains on fluoranthene ensembles towards fluorescence-based detection of 2,4,6-trinitrophenol

A series of novel π-electron rich fluoranthene derivatives (P1–P3) adorned with symmetrical and unsymmetrical alkoxy chains were developed using Diels-Alder reaction. The use of peripheral triethyleneglycol (TEG) chains on fluoranthene enhances its electron donating ability and furnishes decrease in their energy levels and optical band gap. The intense sky-blue fluorescence exhibiting fluoranthene ensembles have been investigated as potential fluorescent chemosensors for the detection of explosive nitroaromatics (NACs). Fluorescence studies demonstrate that emission intensity of P1–P3 was efficiently decreased upon interaction with picric acid (PA) in a dominant static quenching phenomena which is attributed to photoinduced electron transfer process. The limit of detection (LOD) was found to be in the range of 2–20 ppb. The vapour phase sensing study involving thin films of P1–P3 showed efficient quenching response and sensing process is found to be highly reversible. Surface morphology of thin films significantly varied with the type of alkyl chain present on fluoranthene. The thin films are highly selective towards PA in aqueous medium containing commonly interfering nitro-explosives. Contact mode approach using silica gel substrates allows femto-gram detection of trinitrotoluene (TNT) and PA makes these materials as potential chemosensors for real time applications.

Effect of synthesized temperature on the assembly and properties of four lanthanide supramolecular frameworks

Four new lanthanide coordination polymers, [H3O][Ln3(HPA)10(H2O)3·2H2O] (Ln = Pr for 1, Ln = Nd for 2), [Ln2(HPA)6(H2O)4·2H2O] (Ln = Sm for 3, Ln = Tb for 4) (HHPA =3-(4-hydroxyphenyl)propanoic acid), were successfully synthesized and characterized. 1 and 2 are isostructural and have 1D metal chain structure, while 3 and 4 show 0D network with binuclear subunits. The results indicated that the effect of reaction temperature can modulate the final structures. The HPA ligands adopt bidentate chelating and tridentate chelating bridging modes to coordinate with Ln(III) ions in 1-4. It has been shown that 4 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+. KEY WORDS: Sensor, Lanthanide, Structure, Temperature Bull. Chem. Soc. Ethiop. 2019, 33(1), 113-125DOI: https://dx.doi.org/10.4314/bcse.v33i1.11

Dual-Emitting EY@Zr-MOF Composite as Self-Calibrating Luminescent Sensor for Selective Detection of Inorganic Ions and Nitroaromatics

A dual-emitting dye@MOF composite has been synthesized by incorporating a fluorescent dye eosin Y (EY) within a UiO-type zirconium-based metal–organic framework (Zr-MOF) through a synthetic encapsu...

Constitutional isomers of dendrimer-like pyrene substituted cyclotriphosphazenes: synthesis, theoretical calculations, and use as fluorescence receptors for the detection of explosive nitroaromatics

Two constitutionally isomeric bis-pyrenyl phenol dendrons (4and6) and their dendrimer-like cyclotriphosphazene derivatives (5and7) are designed, synthesized and fluorescence detection behaviors are evaluated for nitro aromatic compounds (NACs).

Phosphatase-mimicking activity of a unique penta-nuclear zinc(ii) complex with a reduced Schiff base ligand: assessment of its ability to sense nitroaromatics

A penta-nuclear zinc(ii) complex has been synthesized and characterized. The complex has shown good phosphatase-mimicking activity, which has been evaluated spectrophotometrically. The complex also behaves as a sensor for the detection of nitroaromatics via turn-off fluorescence response.

A series of trinuclear zinc(ii) complexes with reduced Schiff base ligands: turn-off fluorescent chemosensors with high selectivity for nitroaromatics

A series of trinuclear zinc(ii) complexes have been synthesized and characterized by X-ray crystallography. The ability of the complexes to act as sensors for the detection of nitroaromatics in DMF has been assessed.

Self-electrochemiluminescence of poly[9,9-bis(3‘-(N,N- dimethyl amino)propyl)-2,7-fluorene]-alt- 2,7-(9,9- dioctylfluorene)] and resonance energy transfer to aluminum tris(8-quinolinolate)

In this paper, the electrochemiluminescence (ECL) behavior of a hole-transport polymer, poly [9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene]-alt-2,7-(9,9-dio ctylfluorene)] (PFN) was examined with the purpose of finding a novel organic ECL emitter. It was found that the PFN exhibits self-electrochemiluminescence (self-ECL) without any exogenous co-reactants. Quite different from the traditional ECL, the addition of tripropyl amine (TPA) quenched the self-ECL of PFN. PFN ECL intensity reaches a peak during electrochemical oxidation process due to the superposition of self-enhanced ECL, and aggregation quenching of excited state by PFN excimer formation. Aluminum tris(8-quinolinolate) (AlQ3) doped with PFN recovers luminescence intensity with restraining quenching effect via ECL resonance energy transfer from PFN to AlQ3, giving rise to a stable luminescence signal, and hence sensory detection of nitroaromatics. The limits of detections for nitroaromatics can reach down to a level of 10−22 M. This work sets the stage for a novel organic polymer-based ECL emitter without using any toxic exogenous co-reactant, and presents a practical avenue for a prototype of realising sensory detection through signal stabilization via energy resonance energy transfer (ERET).

Water-stable lanthanide-based metal-organic frameworks for rapid and sensitive detection of nitrobenzene derivatives

Two novel lanthanide metal-organic frameworks, namely {[Ln2(NSBPDC)3(H2O)4]·x(H2O)}n (Ln = Eu 1, Tb 2), have been facilely synthesized with 6-nitro-2,2'-sulfone-4,4'-dicarboxylic acid (H2NSBPDC). Structural analyses revealed that the two complexes are both three-dimensional (3D) non-interpenetrating networks based on infinite rod-shaped LnIII carboxylate SBUs and exhibit 1D channels decorated with functional groups. Fluorescence measurements show that complex 1 can serve as a fast and recyclable fluorescence sensor for nitroaromatics detection via a turn-off response with low detection limits. The fluorescence quenching of 1 for nitroaromatics is presumably due to the following two reasons: the photo-induced electronic transfer mechanism and the competitive adsorption mechanism.

A trigonal dodecahedral cadmium(II) complex with zinc(II)–salen type metalloligand: Synthesis, structure, self-assembly and application in the detection of various nitroaromatics via turn-off fluorescence response

A compartmental Schiff base ligand, N,N′-bis(3-ethoxysalicylidene)-2,2-dimethylpropane-1,3-diamine (H2L) has been used to prepare a hetero-trimetallic cadmium(II)/zinc(II) complex, Cd{LZn(NCS)}2. Single crystal X-ray diffraction analysis has confirmed the structure of the complex. The complex behaves as a sensor for the detection of various nitroaromatics via turn-off fluorescence response.

Luminescent sensing and photocatalytic degradation in a new 3D Zn(II)-based highly luminescent metal−organic framework

The intelligent blending of intriguing functionalities in ligands and incorporation of spectroscopically silent metal cations can produce metal-organic frameworks (MOFs) with multifarious applications viz. selective and specific sensing of nitroaromatic compounds (NACs) an important constituent of explosives as well as photocatalytic properties. A new 3D Zn(II)-based metal-organic framework, [Zn4(μ2-OH)2(BDC)3(bip)2] (1) have been synthesized using a mixed ligand strategy using benzene-1,3-dicarboxylic acid (H2BDC) and 1,4-bis(2-methyl-imidazole-yl)-propane (bip) and zinc nitrate via hydrothermal reaction. The framework of 1 adopts a 5-connected 3D network with the Schläfli symbol {33.4.52.62.72}. The luminescent sensing investigation indicated that 1 can behave as a luminescent sensor for highly sensitive detection of nitroaromatics (NACs) especially against 2,4,6-trinitrophenol (TNP). The possible depletion in the photoluminescence intensity of 1 in presence of NACs have been addressed using theoretical calculations which indicated that charge transfer as well as the weak interaction between NACs and MOF may be responsible for the decline in the photoluminescence intensity. The MOF have been used as the photocatalyst for the decomposition of methyl violet (MV). Also, the mechanism for the photocatalysis have been addressed using density of states (DOS) calculations.

Five lanthanide supramolecular frameworks based on mixed 3-(4-hydroxyphenyl)propanoic acid and 1,10-phenanthroline tectons: Crystal structures and luminescent properties

Five new lanthanide coordination polymers, [Ln2(HPA)6(phen)2·solvent] (Ln = Eu, solvent = 4H2O for 1, Ln = Tb, solvent = 2CH3OH for 2, Ln = Pr, solvent = 2H2O for 3, Ln = Nd for 4 and Ln = Er for 5), (HHPA = 3-(4-Hydroxyphenyl)propanoic acid and phen = 1,10-phenanthroline), were successfully synthesized and characterized. The five polymers are isostructural and have 2D supramolecular layered structure. The carboxylic acid ligands adopt bridging, bidentate chelating, and tridentate chelating bridging modes to coordinate with Ln(III) ions. It has been shown that 1 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+. The mixing component of 1/2 = 8:2 not only achieves white-light emission with the CIE coordinate of (0.337, 0.290) upon excitation at 305 nm.

A 2D water-stable metal–organic framework for fluorescent detection of nitroaromatics

By reacting Zn(NO3)2·6H2O and H2btca in the presence of iqo under hydrothermal conditions to give a 2D water-stable metal–organic framework (MOF), {[Zn(btca)(iqo)2]}n (1) (H2btca = benzotriazole-5-carboxylic acid, iqo = isoquinoline), which has been verified by combining X-ray single-crystal diffraction, thermogravimetric (TG) analysis, and infrared (IR) spectrum. Each five-coordinated Zn2+ in 1 exhibits a pentagonal bipyramid geometry defined by four N atoms from two btca2− ligands and two iqo molecules, and one O atom from one carboxylate group of btca2− ligand. Neighbouring Zn2+ are bridged by btca2− ligands to form a 2D ‘fes’-type network, further generating a 3D supramolecular network through hydrogen bonds and π⋯π stacking interactions. Importantly, MOF 1 exhibits strong fluorescence in aqueous solution and can be used for detecting Cr2O72−/CrO42− and nitroaromatics compounds based on fluorescence quenching effects. Furthermore, experimental and theoretical calculations suggest that the fluorescence quenching effect could be mainly ascribed to the electron and energy transfer as well as electrostatic interactions between 1 and nitroaromatics analytes.

Colorimetric paper sensor for sensitive detection of explosive nitroaromatics based on Au@Ag nanoparticles

Rapid, reliable, onsite approaches for detection trace level of trinitrotoluene (TNT) is a pressing necessity for both homeland security and environmental protection. To this end, hydrophilic amine(-NH2) protected Au@Ag nanoparticles (NPs) were developed and fabricated as colorimetric paper sensor for delicate detection of TNT. The as-developed nanoprobe selectively reacts with TNT through classic Meisenheimer complex formation by means of charge transfer process from an electron-rich NH2 group of β-cysteamine to an electron-deficient nitro group on TNT. Due to the absence of this particular interaction of other nitroaromatics, the proposed probe is highly selective for TNT detection with a better linear range (0–20 μg/mL) and limit of detection (LOD) of 0.35 μg/mL. The present work provides a novel and facile strategy to fabricate colorimetric paper sensors with rapid and selective recognition ability for label free analysis of TNT.