Nitrobenzene Compounds Research Articles

Polypod Carboxylic Acid-Rare Earth Complex with High Cyclic Stability for Nitrobenzene Compound Detection.

The 5',5''-bis(4-carboxyphenyl)-[1,1':3',1'':3'',1'''-quaterphenyl]-4,4'''-dicarboxylic (H4L1) ligand has a large conjugated rigid planar structure and good absorption of ultraviolet radiation, which can provide effective "antenna effect". However, rare earth complexes using H4L1 as the sole ligand have not been reported. In this paper, rare earth Eu was combined with H4L1 ligand to produce organic rare earth composite L1-Eu by solvothermal synthesis method. It was found through fluorescence spectroscopy that the emission of L1-Eu complex has a linear response to nitrobenzene compounds. The L1-Eu composite material has a low detection limit for nitrobenzene compounds, with detection limits of 0.910, 8.401, 24.510, and 8.171 µM for nitrobenzene, o-nitrophenol, m-nitrophenol, and p-nitrophenol, respectively. Further more the L1-Eu complex can sensitively respond to nitrobenzene compounds while resisting interference from common metal ions and organic solvents. In particular, L1-Eu composite material has good stability and recyclability. Therefore, L1-Eu composite material can serve as a fluorescent probe for specific detection of nitrobenzene compounds. We believe that the L1-Eu complex provides a new method for fluorescence detection of nitrobenzene compounds.

Bifunctional In-MOFs for Selective and Sensitive Detection of Trace Nitrobenzene Compounds in Water and Possessing High Proton Conductivity.

With the escalating prevalence of terrorism and global environmental pollution, nitroaromatic compounds (NACs) have increasingly come into focus as the primary culprit. To counter these challenges, it is imperative to develop simple and efficient methods for detecting NACs. Considering the electron-deficient structure of NAC molecules, this paper constructed a novel three-dimensional In-MOF with permanent porosity using electron-rich organic molecules 4'-[1,2,2-tris(3',5'-dicarboxy[1,1'-biphenyl]-4-yl)ethenyl]-[1,1'-biphenyl]-3,5-dicarboxylic acid (H8ETTB) for fluorescence detection by photoinduced electron transfer. The results indicated that In-ETTB can sensitively detect trace NACs in water. In-ETTB exhibited the best detection performance for 3-NP, achieving a Ksv value of 8.75 × 104 M-1 with a limit of detection of 0.27 μΜ in aqueous solution; this belongs to a relatively high level among the reported metal organic framework (MOF) materials. Subsequently, anti-interference experiments revealed that In-ETTB exhibits strong specificity fluorescence recognition of NACs, and it could still maintain its structural integrity and fluorescence emission intensity even after 7 cycles of testing. We confirmed that the fluorescence detection of NACs was due to a combined effect of competitive absorption and photoinduced electron transfer through experimental collaboration DFT calculations in detail. Meanwhile, the proton conductivity reached 2.45 × 10-2 S·cm-1 at 98% relative humidity and 90 °C, which is also a high level in MOFs. This work provides a universal method theoretical basis for designing NAC detectors with practical application prospects.

A Pyridazine‐Based Cadmium(II) Organic Framework With pcu Topology as a Luminance Sensor to Nitrobenzene, Al(III), and Cu(II) Ion

ABSTRACTIn the field of water decontamination, the design of luminance sensor for sensitive detection of heavy metal ion toxic and nitroaromatic compounds are important and challenging. Herein, a new luminescent Cd(II) metal–organic framework (MOF), {[Cd2(H2O)3(4‐CPCA)2]·2H2O}n (SNUT‐27) (H2(4‐CPCA) = 1‐(4‐carboxyphenyl)‐4‐oxo‐1,4‐dihydropyridazine‐3‐carboxylic acid) was obtained by the reaction of flexible ligand H2(4‐CPCA) and Cd(II) ions, characterized by single crystal X‐ray diffraction, PXRD, FT‐IR, and TGA, the samples were further analyzed. The analysis of single crystal X‐ray diffraction showed that SNUT‐27 possesses a distinct three‐dimensional spatial arrangement and demonstrates impressive fluorescence properties. Particularly, SNUT‐27 showed a highly sensitive response to the nitro‐aromatic compounds nitrobenzene by fluorescence quenching, and in contrast, showed a fluorescence enhancement response to Al3+ and Cu2+. SNUT‐27 can be effortlessly recycled by simply rinsing with water post‐sensing experiments, showcasing its reusability. Additionally, potential detection mechanisms have been explored.

Ferrate(VI) oxidation of substituted nitrobenzene compounds: Kinetics, degradation, and oxidized products

Nitrobenzene pollutants are discharged in large quantities into water bodies, posing a serious threat to the ecological environment. However, the effects of the nitrobenzene compounds with different structures on the Fe(VI) degradation process remain unclear. This research selects four different substituted nitrobenzene compounds (1,2-dinitrobenzene (1,2-DB), 4-nitrochlorobenzene (4-NCB), pentachloronitrobenzene (PCT), and 3,4-dinitrochlorobenzene (3,4-DTB)) and explores the oxidative degradation effect of ferrate(VI) based on experimental results and theoretical calculations. The reaction of Fe(VI) (800 μM) with each of the four nitrobenzene compounds (40 μM) reflected second-order reaction kinetics at pH 8: 4-NCB (127.08 M−1s−1) > PCT (113.13 M−1s−1) > 1,2-DB (100.1 M−1s−1) > 3,4-DTB (96.459 M−1s−1). Liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) analysis detected the main intermediates, which consisted of hydroxylation, ring-opening, coupling, and amine-based products. Free radicals in the reaction system were identified and analyzed, and hydroxyl radicals and carbon dioxide radicals were found. In addition, density functional theory (DFT) was used to explore the degradation mechanisms in the reaction between each of the four substances and hydroxyl radicals, with the active sites of the nitrobenzenes during the Fe(VI) degradation process determined through the calculation of molecular descriptors. Toxicity analysis with ECOSAR software indicated Fe(VI) reduced the toxicity of the nitrobenzenes. This study provides experimental and theoretical support for the reaction mechanism between nitrobenzenes and Fe(VI), as well as further understanding of the degradation mechanism of nitrobenzene compounds.

Aromaticity of six-membered nitro energetic compounds through molecular electrostatic potential, magnetic, electronic delocalization and reactivity-based indices

The electron density depletion associated with π-hole at the ring center typical of energetic compounds was clearly revealed by the molecular electrostatic potential (ESP). In addition, the spatial arrangement of NO2 groups appears to affect the ESP value in the ring center, and therefore sensitivity to detonation. Indeed, for monocyclic nitrobenzene compounds with the same number of NO2 groups, the ESP value in the ring center decreases as the NO2 groups are more closely spaced. As expected, the central rings become less aromatic as NO2 groups are added. The MCI, PDI, PLR, NICSzz(1), FLU indices are all strongly correlated with the ESP values observed in the ring center of the set of nitrobenzenes. Aromaticity indices based on electron delocalization criteria appear to be very sensitive to small variations in aromaticity. Among magnetic-based indices, only NICSzz(1) is capable to predict small changes in aromaticity. The PLR index derived from conceptual DFT is quite relevant for predicting small variations in aromaticity. According to our results, the most suitable aromaticity index is not based on a single criterion, and that selecting it is more subtle. Therefore, it is important to combine information from several criteria to obtain a more complete description of the aromaticity of the studied compounds.

Modulating covalent organic frameworks with accessible carboxyl to boost superior extraction of polar nitrobenzene compounds from matrix-complicated beverages.

The wide use and high polarity of nitrobenzene compounds (NBCs) have caused a concern for their residues in daily beverages. Herein, the covalent organic frameworks (COFs) with abundant carboxyl were ingeniously designed by introducing a novel modulator, and further developed as solid phase microextraction (SPME) coatings. Due to the enhanced polar interaction, the extraction efficiencies of modified COF for NBCs were sharply increased. After coupling the high-performance SPME fiber with gas chromatograph-mass spectrometry (GC-MS), an ultrasensitive analytical method was developed, with a wide linear range (0.50-5000ng/L), and low limits of detection (0.15-3.0ng/L). More importantly, the method was highly feasible and practical, leading to the precise determinations of trace NBCs from variously matrix-complicated samples. This work provides a viable and efficacious approach for the extraction and analysis of polar pollutants form complicated matrices, and is of great significance for mild COF modification and its extended applications in analytical chemistry.

Fluorescent Noncovalent Organic Framework for Supporting Gold Nanoparticles as Heterogeneous Catalyst with Merits of Easy Detection and Recycle.

A porous noncovalent organic framework with AIE effect is designed and synthesized as the support for gold nanoparticles (AuNPs). The framework is fabricated through the electrostatic complexation between carboxymethyl cellulose and tetraphenylethene-containing ammonium surfactant, which can complex AuNPs via the noncovalent interactions to offer a heterogeneous catalyst. Compared to the covalent modification on cellulose, this noncovalent framework gains superiorities in the catalyst synthesis and the size control of AuNPs. The AIE property and water-insolubility allow such heterogeneous catalysts to be easily detected, separated, and recycled, opening a new pathway for the reduction of nitrobenzene compounds and some dye compounds in aqueous conditions, which present the features of green chemistry. The use of cellulose for developing new heterogeneous metal catalysts, especially in a noncovalent way, would promote the value-added utilization of cellulose. This work provides a design strategy for gaining heterogeneous metal catalysts by taking advantage of natural bioresources.

Solvent-free automated thermal desorption-gas chromatography/mass spectrometry for direct screening of hazardous compounds in consumer textiles

The global production of textiles utilizes numerous large-volume chemicals that may remain to some extent in the finished garments. Arylamines, quinolines, and halogenated nitrobenzene compounds are possible mutagens, carcinogens and/or skin sensitizers. For prevention, control of clothing and other textiles must be improved, especially those imported from countries without regulations of textile chemicals. An automated analytical methodology with on-line extraction, separation, and detection would largely simplify screening surveys of hazardous chemicals in textiles. Automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) was developed and evaluated as a solvent-free, direct chemical analysis for screening of textiles. It requires a minimum of sample handling with a total run time of 38 min including sample desorption, chromatographic separation, and mass spectrometric detection. For most of the studied compounds, method quantification limit (MQL) was below 5 µg/g for 5 mg of textile sample, which is sufficiently low for screening and control of quinoline and arylamines regulated by EU. Several chemicals were detected and quantified when the ATD-GC/MS method was applied in a limited pilot screening of synthetic fiber garments. A number of arylamines were detected, where some of the halogenated dinitroanilines were found in concentrations up to 300 µg/g. This is ten times higher than the concentration limit for similar arylamines listed by the EU REACH regulation. Other chemicals detected in the investigated textiles were several quinolines, benzothiazole, naphthalene, and 3,5-dinitrobromobenzene. Based on the present results, we suggest ATD-GC/MS as a screening method for the control of harmful chemicals in clothing garments and other textiles.Graphical abstract

Rational design of ordered porous nanoparticles for selective extraction of nitrobenzene compounds

The presence of nitrobenzene compounds (NBCs) in the environment has imparted severe threats to public health. Herein, highly selective extraction of polar NBCs from aqueous samples is achieved by rational design of novel extractants. The extraction efficiencies to NBCs are much higher than other analytes (e.g., BTEX, phenols) with subtle differences in structures and molecular dimensions. This extractant (termed as PF-CROSS) was designed by constructing micropores in nanoparticles and reserving electron-donating phenolic hydroxyl groups within the hydrophobic cavities. Owing to the shielding of the phenolic hydroxyl groups from water by the hydrophobic cavities, the polar interactions and π-π electron donor-acceptor specific interactions between the NBCs and PF-CROSS presented, which were confirmed based on Fourier transform infrared (FTIR) spectroscopy, and were further demonstrated to play important roles in selective extraction of NBCs through theoretical modeling. Moreover, the steric effect provided by the micropores further enhanced the extraction selectivity. By fabricating PF-CROSS into solid-phase microextraction fibers, the detection limits of developed method reached as low as 0.32–5.39 ng L−1 for NBCs in water samples. This study provides an efficient and cost-effective extraction phase for highly sensitive detection of NBCs, which is also promising for the recycling of NBCs in the future.

Controllable synthesis of oxygenated carbon supported palladium nanodendrites for highly efficient nitroaromatics reduction

Palladium nanodendrites supported on oxygenated carbon layer (Pd/ O-carbon) have been prepared herein through modulating the mass ratio of Pd (II) precursor and carbon dots derived from sucrose without additional reducing agent. Characterizations of FT-IR, XPS spectra and TEM graphs reveal that oxygen-bearing groups on carbon dots play important role in reducing Pd(II) into Pd(0), controlling nanoparticle growth and stabilizing Pd nanodendrites. The as-prepared Pd/ O-carbon presents size-dependent activity on catalytic p-nitrophenol (4-NP) reduction using NaBH4 as hydrogen donor. The reaction rate constant of 4-NP on Pd/ O-carbon with Pd particle size of 4–7 nm almost triples that on catalyst with Pd nanoparticles of 6–10 nm. Pd / O-carbon can be reused for 10 times without obvious decreased activity, showing a long-term chemical stability in 4-NP reduction reaction. In addition, Pd / O-carbon achieves ∼100% selectivity on nitrobenzene conversion and > 95% selectivity for the hydrogenation of substituted nitrobenzene compounds with methyl-, chloro- and amino- groups to corresponding aniline through tandem reaction with NH3BH3 as hydrogen donor in methanol/ water solvent (volume ratio of 1:3).

A hydrophilic-lipophilic triazine based hyper-crosslinked polymer for efficient enrichment of nitrobenzene compounds

Sensitive, accurate, and simultaneous determination of nitrobenzene compounds (NBs) in environmental water samples is of great significance due to their high risk to human health. In this work, a new triazine-based hyper-crosslinked polymer named CC-Py was constructed via the Friedel-Crafts reaction between cyanuric chloride (CC), pyridine (Py) and 1,2-dichloroethane. Due to its excellent stability, high surface area and hydrophilic-lipophilic (amphiphilic) structure, the CC-Py exhibited a high affinity toward the NBs (nitrobenzene, 2-nitrotoluene, 2,6-dimethylnitrobenzene, 3-nitrotoluene, 4-nitrotoluene, 3-nitrochlorobenzene, 4-nitrochlorobenzene, 2-nitrochlorobenzene, 2,4-dimethylnitrobenzene, 3-nitrobromobenzene, 4-nitrobromobenzene and 4-nitroiodobenzene). Then, a CC-Py based solid-phase microextraction coupled with gas chromatography-flame ionization detection was developed to detect the twelve NBs in real water samples. The results showed that the method had low limits of detection (0.20–0.50 μg L−1), good reproducibility (relative standard deviations (RSDs) < 8.6%) and high enrichment factors (967–1590). The recoveries for the NBs in six different types of water samples were between 90% and 111% with the RSDs less than 7.5%. This work provides a facile and sensitive method for the determination of trace level of NBs in real water samples.

Nickel and oxygen-containing functional groups co-decorated graphene-like shells as catalytic sites with excellent selective hydrogenation activity and robust stability

Encapsulation of metal nanoparticles is one of the promising strategies to overcome the instability of supported metal catalysts. However, improving the hydrogenation activity of multilayer graphene-like encapsulationremains a critical challenge. To address this issue, multilayer graphene-like shells (MGSs) doped with oxygen-containing functional groups (OFGs) encapsulated Ni nanoparticles catalysts (Ni@OC) were synthesized via calcining the calcination of Ni-based metal-organic framework. The Ni@OC catalysts exhibited 100 % nitroaromatics conversion, excellent product selectivity, and superior stability in harsh conditions. Experimental results indicate that the dissociation of H2 and the activation of nitrobenzene compounds can be achieved with the OFGs doped MGSs as the catalytic site in Ni@OC catalysts. In addition, OFGs promote the electron transfer from Ni core to graphene-like shells and result in structural defects of the MGSs to adsorb hydrogenation substrates. Thus, a reasonable design concept was provided to improve the hydrogenation activity of MGSs encapsulated catalysts with the stable existence of metal.

Two new 5-mercapto-1-phenyl-1H-tetrazole-based Cu(I) coordination polymers with double layer structures: Crystal structures, substituent effects and sensing responses to NACs

During the construction of coordination compounds, a minor variation in the steric and electronic characteristics of the substituent on a ligand might have a great impact on the structures and properties of the target compounds. To investigate this issue, two new coordination polymers with double layer structures, [Cu2(MPTZ)I]n (1) and {[Cu(MHPTZ)]·0.5H2O}n (2), have been successfully synthesized through the reactions of CuI and the sulfhydryl tetrazole derivatives (HMPTZ ​= ​5-mercapto-1-phenyl-1H-tetrazole and HMHPTZ ​= ​5-mercapto-1-(4-hydroxyphenyl)- 1H-tetrazole) and characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, infrared spectra and thermogravimetric analysis. In compounds 1 and 2, both (MPTZ)- and (MHPTZ)- coordinate with four Cu(I) ions with distorted tetrahedral geometry in the same coordination modes (μ4-1қN3, 2қN4, 3қS1, 4қS1) to construct the similar two-dimensional (2D) double-layer structures, however, different substituents on ligands have important effects on the introduction of iodide ions and supramolecular forces. For compound 1, a 2D inorganic wavy (CuI)n cationic double-layer structure containing Cu2I2 secondary structural unit with the Cu⋯Cu distance of 2.65 ​Å is observed, but I¯ anions are not involved in the coordination with Cu(I) in compound 2. The difference in crystal structures and compositions of compounds 1 and 2 leads to changes of their fluorescence properties. Compound 1 shows the apparent yellow emission with the maximum at 558 ​nm when exciting at 352 ​nm, which shows sensitive luminescence quenching response to nitrobenzene compounds. However, fluorescent signals of compound 2 were not monitored under UV illumination or on fluorescence spectrophotometer. The results indicate that a minor variation in the substituent on a ligand has a great impact on the structures and properties of the target coordination compounds.

Synthesis of an Acidochromic and Nitroaromatic Responsive Hydrazone‐Linked Pillararene Framework by a Macrocycle‐To‐Framework Strategy

AbstractTailoring the properties of solid‐state organic luminescent materials using a bottom‐up design principle is highly desirable for many applications. Herein, we present a “macrocycle‐to‐framework” strategy to construct macrocycle‐functionalized and hydrazone‐linked functional organic polymers with bright yellowish‐green luminescence and unique solvatochromism behaviors by the condensation of a diacylhydrazine‐functionalized pillar[5]arene with tris(4‐formylbiphenyl)amine. Outperforming their non‐macrocycle‐incorporated counterparts, the pillar[5]arene‐containing materials display amplified sensitivity to acidic conditions with luminescent and colorimetric dual‐modal patterns assisted by the enhanced intramolecular charge transfer (ICT), and exhibit satisfactory responsiveness to nitrobenzene compounds through rapid luminescence quenching with high selectivity and a low detection limit, where the sensing process proceeds through multiple dynamic quenching pathways.

Synthesis of an Acidochromic and Nitroaromatic Responsive Hydrazone-Linked Pillararene Framework by a Macrocycle-To-Framework Strategy.

Tailoring the properties of solid-state organic luminescent materials using a bottom-up design principle is highly desirable for many applications. Herein, we present a "macrocycle-to-framework" strategy to construct macrocycle-functionalized and hydrazone-linked functional organic polymers with bright yellowish-green luminescence and unique solvatochromism behaviors by the condensation of a diacylhydrazine-functionalized pillar[5]arene with tris(4-formylbiphenyl)amine. Outperforming their non-macrocycle-incorporated counterparts, the pillar[5]arene-containing materials display amplified sensitivity to acidic conditions with luminescent and colorimetric dual-modal patterns assisted by the enhanced intramolecular charge transfer (ICT), and exhibit satisfactory responsiveness to nitrobenzene compounds through rapid luminescence quenching with high selectivity and a low detection limit, where the sensing process proceeds through multiple dynamic quenching pathways.

Rational Design of Ordered Porous Nanoparticles for Selective Extraction of Nitrobenzene Compounds

Rational Design of Ordered Porous Nanoparticles for Selective Extraction of Nitrobenzene Compounds

Decoding hexanitrobenzene (HNB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as two distinctive energetic nitrobenzene compounds by machine learning.

Energetic materials (EMs) are a group of special energy materials, and it is generally full of safety risks and generally costs much to create new EMs. Thus, machine learning (ML)-aided discovery becomes highly desired for EMs, as ML is good at risk and cost reduction. This work decodes hexanitrobenzene (HNB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as two distinctive energetic nitrobenzene compounds by ML, in combination with theoretical calculations. Based on a series of highly accurate models of density, heat of formation, bond dissociation energy and molecular flatness, the ML predictions show that HNB is the most energetic among ∼370 000 000 single benzene ring-containing compounds, while TATB possesses a moderate energy content and very high safety, as determined experimentally. This work exhibits the significant power of ML and presents an instructive procedure for using it in the field of EMs. The ML-aided design and highly efficient synthesis and fabrication combined strategy is expected to accelerate the discovery of new EMs.

Phenanthroline bridging graphitic carbon nitride framework and Fe (II) ions to promote transfer of photogenerated electrons for selective photocatalytic reduction of Nitrophenols

Nitrophenols (NPs) are widely used in industries and highly toxic to ecological environment and human health. Because aminophenols (APs) are important chemicals, catalytic reduction of NPs via efficient and environment-friendly strategies is of great importance. Herein, we developed a green photocatalysis route to efficiently convert NPs to APs using a Fe (II) modified graphitic carbon nitride (g-C3N4) photocatalyst, where phenanthroline units were employed to bridge Fe (II) and carbon nitride framework. The optimized sample P-CN-8-Fe presented significantly improved absorption of visible light, separation of photogenerated charges and carrier transportation in comparison with the pristine g-C3N4 and the modified samples of CN-Fe and P-CN-8. Accordingly, the P-CN-8-Fe showed a high conversion (97%) of p-nitrophenol (p-NP) to p-aminophenol (p-AP) under 2 h visible light irradiation, and meanwhile possessed high photocatalytic durability. Its high activity was also demonstrated through photocatalytic reduction of other NPs and nitrobenzene compounds. Finally, a possible mechanism was proposed for the photocatalytic reduction of p-NP by P-CN-8-Fe. This work provides an effective approach to prepare Fe (II) modified g-C3N4 through the bridging effect of phenanthroline group, which is a potential visible light driven photocatalyst for reduction of nitrobenzene derivatives.

Inter- and Intra-Hydrogen Bonding Strategy to Control the Fluorescence of Acylhydrazone-Based Conjugated Microporous Polymers and Their Application to Nitroaromatics Detection

Acylhydrazone-based fluorescent conjugated microporous polymers (CMPs) with inter-and intra-hydrogen bonding-controlled emissive properties were prepared. The synthesized CMPs (BH-CMP and ABH-CMP) were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, solid-state 13C cross polarization/magic angle spinning nuclear magnetic resonance spectroscopy, and photoluminescence spectroscopy. Interestingly, BH-CMP exhibited emission enhancement via adsorption of water molecules, whereas the emission of ABH-CMP, which possesses free amine groups, decreased upon the addition of water molecules. The differences in the emission trends of BH-CMP and ABH-CMP in the presence of water molecules originate from the formation of different hydrogen-bonding networks in each CMP. The acylhydrazone-based CMPs were applied to the detection of nitroaromatic compounds. As a result, ABH-CMP in DMF exhibited high selectivity for 1,3,5-trinitrotoluene (TNT) over other nitroaromatic compounds nitrobenzene, 1-chloro-4-nitrobenzene, 2,3-dichloronitrobenzene, and 2,4-dinitrotoluene.

DNA-templated silver nanoclusters as an efficient catalyst for reduction of nitrobenzene derivatives: a systematic study

Nitrobenzene compounds are highly toxic pollutants with good stability, and they have a major negative impact on both human health and the ecological environment. Herein, it was found for the first time that fluorescent DNA-silver nanoclusters (DNA-AgNCs) can catalyze the reduction of toxic and harmful nitro compounds into less toxic amino compounds with excellent tolerance to high temperature and organic solvents. In this study, the reduction of p-nitrophenol (4-NP) as a model was systematically investigated, followed by expending the substrate to disclose the versatility of this reaction. This report not only expanded the conditions for utilizing catalytic reduction conditions of DNA-AgNCs as an efficient catalyst in the control of hazardous chemicals but also widened the substrate range of DNA-AgNCs reduction, providing a new angle for the application of noble metal nanoclusters.