Detection Of Nitroaromatic Compounds Research Articles

A New 3D 10-Connected Cd(II) Based MOF With Mixed Ligands: A Dual Photoluminescent Sensor for Nitroaroamatics and Ferric Ion.

The precise unification of functional groups and photoluminescence properties can give rise to MOFs that can offer diverse applications like selective detection of nitroaromatic compounds (NACs) which are considered to be an important ingredient of explosive as well as cation and anion sensing. Hence, a new 3D metal-organic framework (MOF) [Cd2(btc)(bib)(HCOO)(H2O)·H2O]n (1) has been synthesized using mixed ligand strategy by solvothermal reaction of cadmium acetate with two ligands viz. 1,3,5-benzenetricarboxylic acid (H3btc) and 1,4-bis(2-methyl-imidazol-1-yl)butane (bib). The MOF 1 possesses highly 10-connected network which is based on {Cd4(btc)2(bib)4} molecular building block. The studies showed that 1 could be taken as the fluorescent sensor for sensitive recognition of NACs, in particular 2,4,6-trinitrophenol (TNP) with notable quenching (Ksv = 5.42 × 104 M−1) and LOD of 1.77 ppm. Additionally, 1 also displayed selective sensing for Fe3+ ions with Ksv = 6.05 × 103 M− 1 and LOD = 1.56 ppm. Also, this dual sensor displayed excellent reusability toward the detection of TNP and Fe3+ ion. Theoretical calculations have been performed to propose the probable mechanism for the sensing luminescence intensity. Calculations indicated that because of the charge transfer and weak interaction that is operating between NACs and MOF, the weakening in the photoluminescence intensity resulted.

A silicon-cored tetraphenyl benzene derivative with aggregation-induced emission enhancement as a fluorescent probe for nitroaromatic compounds detection.

Two benzene with multiple contiguous phenyl substituent derivatives, namely, 1, 2, 3, 4-tetraphenyl benzene (TPB) and bis(1,2,3,4-tetraphenylbenzene-yl) diphenylsilane (TPB-Si), were synthesized by the Knoevenagel/Diels-Alder method. TPB and TPB-Si both showed aggregation-induced emission enhancement (AIEE) properties in tetrahydrofuran/water mixtures. The fluorescence-quenching behaviors of the two compounds with different nitroaromatic compounds were also investigated. TPB and TPB-Si both showed low detection limit, high sensitivity, and high quenching efficiency in detecting nitroaromatic compounds. Furthermore, the two compounds in aggregate state exhibited much better detection abilities than in THF solution. And TPB-Si exhibited better detection ability than TPB in both solution and aggregate state. The reason could be attributed to the special tetrahedral molecular structure of TPB-Si, which was demonstrated by theoretical calculations and crystal structures. Moreover, TPB-Si in solid film also exhibited excellent detection performance to nitroaromatic explosive vapor. This work may serve as a basis for designing new organic materials with great efficiency and sensitivity in fluorescence detection.

Luminescent Lanthanide-Based Probes for the Detection of Nitroaromatic Compounds in Water.

A new mixed pyridyl–carboxylate ligand with two picolinate chromophores and a flexible linear spacer, potassium 2,2′-(butane-1,4-diylbis((pyridin-2-ylmethyl)azanediyl))diacetate (K2bpbd), which is obtained in high yield and spectroscopically characterized, has been utilized to make new lanthanide complexes, namely, [Ln(bpbd) (H2O)2(NO3)]·xH2O, where Ln = Tb (1) and x = 6, Ln = Sm (2) and x = 7, and Ln = Dy (3) and x = 7. These complexes have been extensively characterized by various spectroscopic techniques (UV–vis and Fourier transform infrared spectroscopy), elemental analyses, thermogravimetric analysis, field emission scanning electron microscopy, and powder X-ray diffraction. These show very intense characteristic luminescence features that confirm the antenna effect of the ligand on the metal center. These complexes have been utilized for the detection of various nitroaromatic compounds. Among these three complexes, 1 is found to be the best for the selective sensing of 2,4,6-trinitrophenol in water with a detection limit of (0.35 ± 0.05) ppm. Its Stern–Volmer constant, KSV [(5.48 ± 0.1) × 104 M–1], is one of the highest among similar sensors reported so far.

Hexanuclear 3d − 4f metal–organic cages assembled from a carboxylic acid‐functionalized tris‐triazamacrocycle for highly selective fluorescent sensing of picric acid

Two LnIII ions are sandwiched by dinuclear CoII building blocks derived from a tris‐triazamacrocyclic ligand bearing pendant carboxylic acid functionality, 1,3,5‐tris((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐benzene (H6L), giving rising to two nanoscale heterometallic metal–organic cages formulated as [Co4Ln2(LH2.5)2(H2O)4]·(ClO4)6·NO3·nH2O [Ln = Dy, n = 12 (1); Ln = Yb, n = 9 (2)], whose internal cavity accommodates a guest NO3− anion. Their hexanuclear cage‐like architectures are maintained both in solution and solid states as confirmed by mass spectrum as well as X‐ray diffraction experiments. These two cages display ligand‐based fluorescence emissions and therefore both were chosen to be operated as fluorescent chemosensors for the detection of nitroaromatic compounds. Attractively, these metal–organic cages allow highly selective and sensitive detection of picric acid (PA) over other nitroaromatics in solution and suspension, and the fluorescence resonance energy transfer (FRET) between the cage probes and PA is mainly responsible for the remarkable detection efficiency.

Ultrasonic-Assisted Synthesis of a Zn(II) Coordination Polymer in Aqueous Media and Its High-Performance Luminescent Sensing for 2,4,6-Trinitrophenol

A novel Zn(II) coordination polymer based on 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol (Hpzt), namely [Zn(pzt)2]n or Zn-CP, was synthesized by two different synthetic methods. The bulk polycrystals and single crystals of Zn-CP were obtained by a conventional solvothermal method at 90 °C. Zn-CP exhibits a two-dimensional (2D) coordination network that contains the uncoordinated Lewis basic sites within each layer. Interestingly, a simple and environmentally friendly sonochemical synthesis of the Zn-CP in an aqueous media could be performed at room temperature. The optimal synthetic conditions were studied. The uniform microplates of Zn-CP were obtained within 30 min with the addition of pyridine, acting as a size modulator and a deprotonating reagent. The influence of the amount of the modulator and the sonication time on the crystal size was investigated. Moreover, a Zn-CP suspension in an ethanolic media has been used as a luminescence sensor for the detection of nitroaromatic compounds. It shows highly sel...

Ti-Catalyst Biomimetic Sensor for the Detection of Nitroaromatic Pollutants.

An electrode modified by a Ti complex in Nafion was used in the electrochemical detection of nitroaromatic compounds (NACs). The catalyst reduced nitroaromatic groups by a six-electron process with a high apparent rate constant, k1, which was estimated to be at least 19 000 mol-1 L s-1 by simulation of the first step of the cathodic reduction of 4-nitrophenylacetic acid, which was used as model molecule. The modified electrode was prepared and optimized in terms of Nafion and catalyst concentrations. In the chosen analytical medium, the Ti-catalyst-containing electrode showed good stability in the presence of nitro species. A standard deviation around 15% was calculated on the analysis performed with 28 different modified electrodes, which could be expected for a drop-coating process. We show that the modified electrode detects several nitroaromatic compounds such as nitrophenols, mononitroaniline, and dinitrotoluene with detection limits ranging from 1 × 10-4 to 9 × 10-4 g L-1 (0.2 × 10-6 to 5.1 × 10-6 mol L-1). As an interesting feature, the sensor exhibits good selectivity toward NAC detection because titanocene does not catalyze the reduction of nitroaliphatic compounds.

Two triphenylamine-based luminescent metal–organic frameworks as a dual-functional sensor for the detection of nitroaromatic compounds and ofloxacin antibiotic

Two solvent-induced luminescent MOFs have been synthesized and MOF1 can be employed as a dual-functional fluorescence sensor for nitroaromatics and antibiotics.

Ligand controlled structure of cadmium(II) metal-organic frameworks for fluorescence sensing of Fe3+ ion and nitroaromatic compounds

Three cadmium(II) metal-organic frameworks (MOFs) based on tetracarboxylate ligands, namely [Cd2(TTTA)(DMF)3]·2DMF (1), [Cd2(TB)(H2O)4]·3DMF·H2O (2) and [Cd(TEB)0.5]·2DMF·4H2O (3) have been designed and synthesized. Complex 1 is a 2-dimensional (2D) 3,4-connected network with 3,4L13 topology, complex 2 features a 3-dimensional (3D) 3,4-connected tfa topology with a 2-fold interpenetrating structure and complex 3 has a 3D 4-connected dia topology with a 4-fold interpenetrating structure. Interestingly, 2 exhibits permanent pores and selective adsorption of CO2 over CH4. In addition, 2 shows fluorescence sensing of Fe3+ ion and rapid detection of nitroaromatic compounds (NACs) through fluorescence quenching.

High-sensitivity detection of nitroaromatic compounds (NACs) by the pillared-layer metal-organic framework synthesized via ultrasonic method

Nanorods of zinc(II) based metal-organic framework (MOF) were prepared via ultrasonic method without any surfactants at room temperature and atmospheric pressure. Control of particle size and morphology was enhanced in this synthesis method. Nanorods of pillared-layer metal organic framework, [Zn2(ubl)2(bipy)]·DMF (TMU-18), where ubl (urea-based ligand) is 4,4′-carbonylbis(azanediyl)dibenzoic acid, 4,4′-Bipyridine (bipy) DMF = N,N-dimethyl formamide), was synthesized under ultrasound irradiation in different concentrations of initial precursor. The nano structure and morphology of the synthesized MOF were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction, elemental analysis and FT-IR spectroscopy. Moreover, Fluorescence emissions of nanorods have been studied. Luminescent MOFs (LMOFs) have shown great potential as sensor for various nitro explosives by modulating the luminescence behavior in presence of nitro explosives. Urea-functionalized MOF shows high selectivity for sensing of the nitro explosive 2,4,6-trinitrophenol (TNP) even in the presence of other nitroaromatic compounds in methanol solution. Fluorescence intensity decreased with increasing contents of nitroaromatics in organic solution due to fluorescence quenching effect. The ultrasound method has some advantages such as short duration time of reaction, no need to high temperatures and pressures for synthesis nano-materials and low costs in comparison to other methods. Considering these advantages we used ultrasonic method to produce these nanorods which show high sensitivity in detecting nitroaromatics.

An instant reused luminescent mixed matrix membrane sensor for convenient phenolic nitro-explosives detection

Economical and simplified detection of nitroaromatic compounds (NACs) is urgently needed as environmental and security situation gets gradually serious. Herein, we report an instant reused luminescent mixed matrix membrane (MMM) sensor for selective detection of NACs. This sensor applies waste polystyrene as matrix and luminescent lanthanide complex [Tb2(4-Msal)6(H2O)4]·6H2O (Tb-4-Msal, where 4-Msal = 4-methylsalicylate) as fillers. The as-prepared Tb-4-Msal MMM sensor exhibits excellent stability in aquatic media with common ions and wide range pH of 1–14. The sensor presents immediate response towards phenolic nitro-explosives in a variety of NACs. With a measurement in existence of common NACs and in water of Pearl River, the MMM sensor proved its potential in practical usage. What’s more, the sensor can be handily reused only by immersing it in the tap water for 1 min with bare luminescence intensity loss, demonstrates an unusual instant reusable performance with simple recover process. This lanthanide complex based luminescent MMM sensor provides an underlying platform of convenient phenolic nitro-explosives detection in aqueous environment monitoring, as well as develops the way of utilizing waste materials in sensor manufacturing.

Selective fluorescence sensing of p-nitroaniline and Fe3+ ions by luminescent Eu-based metal-organic framework

PurposeThe purpose of this study is to develop luminescence sensors for the detection of nitroaromatic compounds (NACs) and metal ions to protect human health and prevent environmental pollution.Design/methodology/approachThe composition and morphology of Eu-metal-organic frameworks (MOF) (1) were well characterized by powder X-ray diffraction, elemental analyses, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The emission spectrum displays that 1 has significant characteristic emission bands of Eu(III) ions. The authors further investigated the fluorescence sensing performances of 1 to NACs and metal ions.FindingsThe results show that Eu-MOF (1) exhibits significant fluorescence quenching effect toward p-nitroaniline and Fe3+ ions with good stability and recyclability. This means that 1 can be used as a multifunctional sensing material for the detection of p-nitroaniline and Fe3+ ions.Originality/valueThe authors have successfully synthesized a fluorescence Eu-based sensing material under hydrothermal conditions. In addition, the fluorescence property and sensing performances for detecting NACs and metal ions were studied. The results suggest that 1 has highly selective fluorescence quenching toward p-nitroaniline and Fe3+ ions with not only high sensitivity and selectivity but also excellent stability and recyclability. Furthermore, this study has confirmed that the multifunctional MOF material is very useful in environment pollutants’ detection and monitoring.

Core-modified of fluoranthene with "propeller" structure for highly sensitive detection of nitroaromatic compounds.

Two fluoranthene derivatives with "propeller" structure, named as 7,8,9,10-tetraphenylfluoranthene (TPFA) and 3-phenoxy-7,8,9,10-tetraphenyl fluoranthene (PO-TPFA), were designed and synthesized by introducing outer phenyl and phenoxy substituents to fluoranthene. Given the steric hindrance of this unique structure, both organic dyes exhibited similar fluorescence spectra and strong fluorescence emission from the solution to the film state. The introduction of a phenoxy group showed obvious influence to the molecular optical properties of fluoranthene. Density functional theory calculations were further conducted to verify this finding. Both dyes were used as fluorescent probes and exhibited and sensitive fluorescence response to nitroaromatic explosives and highly selectivity to picric acid. Furthermore, PO-TPFA exhibited better detection performance to nitroaromatic explosives than TPFA. This work can serve as a guide for molecular fluorescence design because these dyes possess excellent fluorescence in solution and film states and can be used for the sensitive fluorescence detection of nitroaromatic explosives.

Bifunctional Porphyrin-Based Nano-Metal-Organic Frameworks: Catalytic and Chemosensing Studies.

The use of 5,10,15,20-tetrakis( p-phenylphosphonic acid)porphyrin (H10TPPA) as a linker in the preparation of porphyrin-based metal-organic frameworks (Por-MOFs) through coordination to lanthanides cations is reported. The resulting unprecedented materials, formulated as [M(H9TPPA)(H2O) x]Cl2· yH2O [ x + y = 7; M3+ = La3+ (1), Yb3+ (2), and Y3+ (3)], prepared using hydrothermal synthesis, were extensively characterized in the solid-state, for both their structure and thermal robustness, using a myriad of solid-state advanced techniques. Materials were evaluated as heterogeneous catalysts in the oxidation of thioanisole by H2O2 and as chemosensors for detection of nitroaromatic compounds (NACs). Nano-Por-MOFs 1-3 proved to be effective as heterogeneous catalysts in the sulfoxidation of thioanisole, with Por-MOF 1 exhibiting the best catalytic performance with a conversion of thioanisole of 89% in the first cycle and with a high selectivity for the sulfoxide derivative (90%). The catalyst maintained its activity roughly constant in three consecutive runs. Por-MOFs 1-3 can be employed as chemosensors because of a measured fluorescence quenching up to 70% for nitrobenzene, 1,4-dinitrobenzene, 4-nitrophenol, and phenol, with 2,4,6-trinitrophenol exhibiting a peculiar fluorescence profile.

High-selectivity Detection of 2,4,6-Trinitrophenol Based on Fluorescent Mg-MOF-74 in Ethanol Solution

Mg-MOF-74 has adsorption capacity while less research is about its luminescent properties. In this work, the fluorescent properties of Mg-MOF-74 were studied and characterized. The results show that Mg-MOF-74 exhibits excellent fluorescent properties and, most strikingly, selective sensing detection for nitroaromatic compounds(NACs), 2,4,6-trinitrophenol(PA) in particular, making it a promising PA-selective luminescent probe. This work demonstrates the application of MOFs in the detection of NACs with good selectivity.

Pyrene functionalized cyclotriphosphazene-based dyes: Synthesis, intramolecular excimer formation, and fluorescence receptor for the detection of nitro-aromatic compounds

A series of pyrene functionalized cyclotriphosphazene-based dyes, mono- (1), cis- and trans-non-geminal-bis (2a, 2b), geminal-bis-(4), geminal-tetrakis-(6), and hexakis-(7) derivatives, has been synthesized and, their photophysical properties such as molar absorption coefficients (ε), fluorescence emission, fluorescence quantum yields (ϕF) and fluorescence lifetimes (τF) have been investigated. On the relationship between molecular geometry and emission properties of dyes has been also discussed. It was found that bis-pyrene substituted compounds (2a, 2b and 4) exhibited three different fluorescence spectra which consisted of an excimer, a monomer and both monomer and excimer emissions in the same solvents, respectively. The emission difference between 2a and 2b clearly revealed that intramolecular excimer formation, which permitted to characterize unambiguously as a cis-isomer, observed for compound 2a whereas 2b showed only monomer emission and consequently as a trans-isomer. These formation behaviors were supported by DFT calculation with wB97XD/6-31G (d, p) and 31P NMR spectroscopy on addition of chiral solvating agent (CSA) experimental studies. Additionality, sensing behaviors of 2a, 4 and 6 were investigated for the detection of nitro aromatic compounds (NACs). It was found that the fluorescence emissions of the compounds were significantly quenched in presence of TNT, nitrobenzene or nitrophenol, while other tested metal ions induced no spectral changes.

Conjugated microporous polymers based on biphenylene for CO2 adsorption and luminescence detection of nitroaromatic compounds

Conjugated microporous polymers based on biphenylene exhibit selective adsorption CO2 over CH4 and N2 and luminescence sensing for picric acid.

Linear and V-shaped push–pull systems on a base of pyrimidine scaffold with a pyrene-donative fragment for detection of nitroaromatic compounds

New fluorophores based on pyrimidines, bearing a pyrene electron-donating fragment, have been designed, synthesized and characterized. The fluorescence behavior of these fluorophores has been evaluated toward nitroaromatic compounds, including such well-known explosives, as 2,4-dinitroanisole, picric and styphnic acids, 1,3,5-triethoxy-2,4,6-trinitrobenzene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, 2,4,6-triamino-1,3,5-trinitrobenzene and nitrobenzene. The detection limits for these fluorophores in relation to nitroaromatic compounds in acetonitrile solution proved to be in the range from 10−1 to 10−7 mol/L. The sensor prototypes for handheld sniffer «Nitroscan» (Plant «Promautomatika», Ekaterinburg, Russia) based on these fluorophores have been fabricated and used for applications, as illustrated by reusable, reversible and sensitive fast detection of nitrobenzene and 2,4,6-trinitrotoluene in vapor phase concentrations up to 6 and 5 ppb, respectively.

Synthesis of Novel Fluorescent Cellulose Derivatives and Their Applications in Detection of Nitroaromatic Compounds

A series of fluorescent cellulose derivatives (AC-AET-DMANMs) with different degrees of substitution (DS) were successfully prepared. First, allyl cellulose (AC) was synthesized from cellulose in NaOH/urea aqueous solution, and then 2-aminoethanethiol (AET) was introduced onto the cellulose backbone via a thiol–ene click reaction. Finally, the fluorescent groups were introduced by the reaction of the AET-modified AC with 4-dimethylamine-1,8-naphthalic anhydride (DMANA). The structure and fluorescent properties of AC-AET-DMANMs were characterized by elemental analysis and FT-IR, 1H NMR, UV–vis, and fluorescence spectroscopy. AC-AET-DMANM with lower DSDMANM (referring to the DS of naphthalimide groups, ≤0.25) was soluble in DMSO. AC-AET-DMANM of DSDMANM ≤ 0.09 displayed stable fluorescence in DMSO and even in the solid state. The emission of AC-AET-DMANM in DMSO quantitatively and sensitively responded to 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenylhydrazine (DNH) by fluorescence quenching, and the limi...

Pyridoxamine driven selective turn-off detection of picric acid using glutathione stabilized fluorescent copper nanoclusters and its applications with chemically modified cellulose strips

The present work reports the interaction of various vitamin B6 cofactors with the red emitting glutathione stabilized copper nanoclusters (GSH-CuNCs). Addition of pyridoxamine (PM) resulted a new turn-on band at 410nm due to the possible adsorption over the surface of GSH-CuNCs. The nano-assembly PM-GSH-CuNCs was applied for the selective detection of nitro-aromatic compounds. Upon addition of picric acid (PA), the fluorescence of PM-GSH-CuNCs was selectively quenched at 410nm and ~ 625nm among the other tested nitro-aromatic compounds. With a linearity range from 9.9μM to 43μM, the concentration of PA can be detected down to 2.74μM. The high selectivity exhibited by the nano-assembly allows to detect PA in real samples like tap water, river water and matchstick. Advantageously, the nano-assembly PM-GSH-CuNCs was chemically adsorbed over the cellulosic strips and applied for the naked-eye detection of PA down to 1μM.

Mechanosynthesis of Second‐Sphere Coordination Salts and Chelating Complexes: Structures, Reversible Transformations, and Nitroaromatic Explosives Sensing

We have investigated the mechanosynthesis of a series of second-sphere salts (guest⊂ [H2L]2+*[MCl4]2−) and the reversible transformations with their chelating coordination complexes [MCl2(L)], via dehydrochlorination reaction, L = N,N′-dibenzyl-(±)-trans-1,2-diaminocyclohexane. The second-sphere salts and their corresponding coordination complexes show different solid state fluorescence spectra. The complex (ZnCl2)(L)(2′) can act as a fluorescent sensor for highly sensitive detection of nitroaromatic compounds through fluorescence quenching.