NO2 Interactions Research Articles

A DFT study of superior adsorbate–surface bonding at Pt-WSe2 vertically aligned heterostructures upon NO2, SO2, CO2, and H2 interactions

This study investigates the potential of platinum (Pt) decorated single-layer WSe2 (Pt-WSe2) monolayers as high-performance gas sensors for NO2, CO2, SO2, and H2 using first-principles calculations. We quantify the impact of Pt placement (basal plane vs. vertical edge) on WSe2’s electronic properties, focusing on changes in bandgap (ΔEg). Pt decoration significantly alters the bandgap, with vertical edge sites (TV-WSe2) exhibiting a drastic reduction (0.062 eV) compared to pristine WSe2 and basal plane decorated structures (TBH: 0.720 eV, TBM: 1.237 eV). This substantial ΔEg reduction in TV-WSe2 suggests a potential enhancement in sensor response. Furthermore, TV-WSe2 displays the strongest binding capacity for all target gases due to a Pt-induced “spillover effect” that elongates adsorbed molecules. Specifically, TV-WSe2 exhibits adsorption energies of − 0.5243 eV (NO2), − 0.5777 eV (CO2), − 0.8391 eV (SO2), and − 0.1261 eV (H2), indicating its enhanced sensitivity. Notably, H2 adsorption on TV-WSe2 shows the highest conductivity modulation, suggesting exceptional H2 sensing capabilities. These findings demonstrate that Pt decoration, particularly along WSe2 vertical edges, significantly enhances gas sensing performance. This paves the way for Pt-WSe2 monolayers as highly selective and sensitive gas sensors for various applications, including environmental monitoring, leak detection, and breath analysis.

Surface Modification Strategy for Enhanced NO2 Capture in Metal-Organic Frameworks.

The interaction strength of nitrogen dioxide (NO2) with a set of 43 functionalized benzene molecules was investigated by performing density functional theory (DFT) calculations. The functional groups under study were strategically selected as potential modifications of the organic linker of existing metal–organic frameworks (MOFs) in order to enhance their uptake of NO2 molecules. Among the functional groups considered, the highest interaction energy with NO2 (5.4 kcal/mol) was found for phenyl hydrogen sulfate (-OSO3H) at the RI-DSD-BLYP/def2-TZVPP level of theory—an interaction almost three times larger than the corresponding binding energy for non-functionalized benzene (2.0 kcal/mol). The groups with the strongest NO2 interactions (-OSO3H, -PO3H2, -OPO3H2) were selected for functionalizing the linker of IRMOF-8 and investigating the trend in their NO2 uptake capacities with grand canonical Monte Carlo (GCMC) simulations at ambient temperature for a wide pressure range. The predicted isotherms show a profound enhancement of the NO2 uptake with the introduction of the strongly-binding functional groups in the framework, rendering them promising modification candidates for improving the NO2 uptake performance not only in MOFs but also in various other porous materials.

TNB/TNCB cocrystal – an insensitive energetic cocrystal with low melting point

Effective cocrystallization technology plays a significant role in regulating the properties of existing explosives. A new energetic cocrystal consisting of TNB and TNCB in a 1:1 molar ratio was synthesized via slow evaporation of absolute alcohol. The crystal structure of TNB/TNCB cocrystal was verified by single crystal X-ray diffraction. Four main non-covalent interactions were conducive in building the TNB/TNCB cocrystal, including C–H—O, C–Cl—O, NO2—π and NO2—NO2 interactions. Through researching the different percentages of atom contacts, the NO2—π interaction is found to be the dominant non-covalent interaction. The melting points, impact sensitivities and detonation performances of cocrystal and coformers were measured and analyzed. The TNB/TNCB cocrystal was found to have a melting point of 100.2°C, which is between those of TNB (82.4°C) and TNCB (123.7°C). The cocrystal impact sensitivity (H50 = 97.5 cm) was superior to that of TNB (H50 = 59.6 cm) on account of the presence of insensitive TNCB (H50 = 118.9 cm), which is more insensitive than TNT (H50 = 83.5 cm, a common low-sensitive explosive). Moreover, the cocrystal detonation performance (detonation velocity: 7547 m/s, detonation pressure: 25.5 GPa) is also greater than that of TNT. Therefore, the TNB/TNCB cocrystal may be a promising future melt-cast carrier for insensitive melt-cast explosives.

NO2 Interactions with MoO3 and CuO at Atmospherically Relevant Pressures

NO₂ Interactions with MoO₃ and CuO at Atmospherically Relevant Pressures

Air Pollutants' Concentrations Are Associated with Increased Number of RSV Hospitalizations in Polish Children.

Respiratory syncytial virus (RSV) contributes significantly to pediatric hospitalizations. An association between air pollution and an increased number of RSV cases has been suggested. We sought to evaluate the short-term impact of air pollutants on RSV hospitalizations in Polish children in the period 2010–2019. Daily concentrations of PM10 and PM2.5 (particulate matter with an aerodynamic diameter less than or equal to 10 μm and 2.5 μm, respectively) and nitrogen dioxide (NO2) were analyzed in general regression models (GRM) to establish their influence and full interaction scheme. Significant seasonal and annual periodicity among 53,221 hospitalizations was observed; finally, data from the 2012–2019 RSV high-risk seasons created models for seven agglomerations. The addition of PM2.5, PM10, and NO2 to the basic model for RSV seasonality explained 23% (4.9–31%, univariate model) to 31.4% (8.4–31%, multivariate model) of the variance in RSV hospitalizations. A 10 μg/m3 increase in PM2.5, PM10, and NO2 concentrations was associated with 0.134 (0.087–0.16), 0.097 (0.031–0.087), and 0.212 (0.04–0.29) average increases in hospitalizations, respectively. In the multivariate models, PM2.5, PM10, and NO2 alone, as well as PM2.5–NO2, PM2.5–PM10, and PM10–NO2 interactions, were associated with hospitalizations in some of the locations, while the metaregression showed statistically significant interactions between each of the pollutants, and between the pollutants and the year of the study. The inclusion of PM2.5, PM10, and NO2 in GRM explains a significant number of RSV hospitalizations. The pollutants act alone and interact together in a varied manner. Reducing air contamination might decrease the costs of hospital healthcare.

Bulk polarity of 3,5,7-trinitro-1-azaadamantane mediated by asymmetric NO2(lone pair)...NO2(π-hole) supramolecular bonding.

Molecular crystals exhibiting polar symmetry are important paradigms for developing new electrooptical materials. Though accessing bulk polarity still presents a significant challenge, in some cases it may be rationalized as being associated with the specific molecular shapes and symmetries and subtle features of supramolecular interactions. In the crystal structure of 3,5,7-trinitro-1-azaadamantane, C9H12N4O6, the polar symmetry of the molecular arrangement is a result of complementary prerequisites, namely the C3v symmetry of the molecules is suited to the generation of polar stacks and the inherent asymmetry of the principal supramolecular bonding, as is provided by NO2(lone pair)...NO2(π-hole) interactions. These bonds arrange the molecules into a trigonal network. In spite of the apparent simplicity, the structure comprises three unique molecules (Z'= 1/3+1/3+1/3), two of which are donors and acceptors of three N...O interactions and the third being primarily important for weak C-H...O hydrogen bonding. These distinct structural roles agree with the results of Hirshfeld surface analysis. A set of weak C-H...O and C-H...N hydrogen bonds yields three kinds of stacks. The orientation of the stacks is identical and therefore the polarity of each molecule contributes additively to the net dipole moment of the crystal. This suggests a special potential of asymmetric NO2(lone pair)...NO2(π-hole) interactions for the supramolecular synthesis of acentric materials.

Divergent Adsorption-Dependent Luminescence of Amino-Functionalized Lanthanide Metal-Organic Frameworks for Highly Sensitive NO2 Sensors.

A novel gas sensing mechanism exploiting lanthanide luminescence modulation upon NO2 adsorption is demonstrated here. Two isostructural lanthanide-based metal-organic frameworks (MOFs) are used, including an amino group as the sensitive recognition center for NO2 molecules. The transfer of energy from the organic ligands to Ln is strongly dependent on the presence of NO2, resulting in an unprecedented photoluminescent sensing scheme. Thereby, NO2 exposition triggers either a reversible enhancement or a decrease in the luminescence intensity, depending on the lanthanide ion (Eu or Tb). Our experimental studies combined with density functional theory and complete active space self-consistent field calculations provide an understanding of the nature and effects of NO2 interactions within the MOFs and the signal transduction mechanism.

Design, preparation, characterization and formation mechanism of a novel kinetic CL-20-based cocrystal.

2,4,6,8,10,12-Hexanitrohexaazaisowurtzitane (CL-20)-based cocrystals have gained increasing attention as a means of obtaining insensitive high explosives. However, the design of ideal candidates for these cocrystals remains difficult. This work compares the crystal energies of the CL-20-dinitrobenzene (DNB) and CL-20-2,4,6-trinitrotoluene (TNT) cocrystals with those of the respective pure coformers. The results indicate that the cocrystal formation is driven by the differences in the energies of the cocrystals and the coformers. Furthermore, analysis via Hirshfeld surfaces and two-dimensional fingerprint plots confirms that the O...O, O...H, O...N and C...O interactions were the main force for stabilizing the CL-20-based cocrystal structure. Based on these findings, a novel energetic-energetic cocrystal of CL-20-2,4,6-trinitrophenol (TNP) was designed and prepared by means of a rapid method for solvent removal. The crystal structure was investigated via powder X-ray diffraction methods, solid-state nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. The results revealed that the O-H...O hydrogen bonding interaction between the phenolic hydroxyl group of TNP and nitro groups of CL-20, as well as nitro...π, nitro...nitro and ONO2...π(N)NO2 interactions, based on the benzene ring and nitro groups, are the main interactions occurring in the cocrystal.

Efficient adjustment of product selectivity using controllable Pd nanoparticles in nitroarene hydrogenation

Product selectivity adjustment is a much-studied topic in mesoscience that is critical for industrial processes and strongly related to reaction intermediates formed by interactions between catalytic active sites and reactants. Herein, we report efficient adjustment of the product selectivity in the hydrogenation of substituted nitroarenes via rational reaction intermediates achieved using controllable Pd nanoparticles. Pd nanoparticles fixed within zeolite Beta crystals (Pd@Beta) afforded rational Pd–NO2 interactions, in which the Pd nanoparticle-adsorbed substituted nitroarenes, such as nitrobenzaldehyde, were reasonably hydrogenated into the corresponding aminobenzaldehyde. However, for Pd nanoparticles supported on the external surfaces of zeolite beta crystals, various side products were obtained owing to the coexistence of PdNO2 and PdCO interactions. When Pd nanoparticles were artificially controlled in various positions in a fixed-bed reactor, the product selectivity was significantly affected. These results demonstrate the importance of molecular adsorption and diffusion processes in adjusting product selectivity in catalytic reactions.

Does the stability of the stacking motif surpass the planar motif in 2-amino-4-nitrophenol? - a CCSD(T) analysis.

In this work we analyzed O-H...O, O-H...N, and N-H...O contacts existing in the 2-amino-4-nitrophenol structure engaged in ANP molecules through quantum chemical methods. Furthermore, the above contacts were favored to comprehensively understand the stability of noncovalent interactions, π stacking and hydrogen bonding, surviving in 2-amino-4-nitrophenol. The geometries of π stacking and hydrogen bond interactions between two 2-amino-4-nitrophenols were optimized at BLYP-D3/def2-QZVP with dispersion 3 and MP2/cc-pVTZ levels of theory, and their stability was compared using the CCSD(T) interaction energies. The analyses predicted a particularly strong π stacking interaction of 2-amino-4-nitrophenol with hydrogen bond due to the narrow equivalent configuration of NO2 interactions with the other 2-amino-4-nitrophenols. Furthermore, this work focused on analyzing the stability of the individual hydrogen bonds existing in planar and stacked arrangements. Graphical abstract Stacked and planar motif in 2-amino-4-nitrophenol.

NOx-Hydrocarbon Kinetics Model Validation Using Measurements of H2O in Shock-Heated CH4/C2H6 Mixtures With NO2 as Oxidant

One method frequently used to reduce NOx emissions is exhaust gas recirculation, where a portion of the exhaust gases, including NOx, is reintroduced into the combustion chamber. While a significant amount of research has been performed to understand the important fuel/NOx chemistry, more work is still necessary to improve the current understanding on this chemistry and to refine detailed kinetics models. To validate models beyond global kinetics data, such as ignition delay time or flame speed, the formation of H2O was recorded using a laser absorption diagnostic during the oxidation of a mixture representing a simplistic natural gas (90% CH4/10% C2H6 (mol)). This mixture was studied at a fuel lean condition (equivalence ratio = 0.5) and at atmospheric pressure. Unlike in conventional fuel-air experiments, NO2 was used as the oxidant to better elucidate the important, fundamental chemical kinetics by exaggerating the interaction between NOx and hydrocarbon-based species. Results showed a peculiar water formation profile, compared to a former study performed in similar conditions with O2 as oxidant. In the presence of NO2, the formation of water occurs almost immediately before it reaches more or less rapidly (depending on the temperature) a plateau. Modern, detailed kinetics models predict the data with fair to good accuracy overall, while the GRI 3.0 mechanism is proven inadequate for reproducing CH4/C2H6 and NO2 interactions.

NO2···NO2 Contacts under Compression: Testing the Forces in Soft Donor–Acceptor Interactions

Intermolecular forces and energies are not directly observable and cannot be retrieved from a crystal structure determination, which simply pictures the resulting equilibrium between forces. In this work, using compression to sample the repulsive part of potentials, we show that high pressure studies may give insight in the nature of intermolecular forces. We focus our attention on controversial π* ← n interactions between NO2 groups, which exhibit several conformations. Using X-ray diffraction and ab initio calculations, we describe the high pressure behavior and phase transition of 4-amino-4′-nitrobiphenyl. To deepen our understanding of the nature of NO2···NO2 interactions, we used several theoretical tools, including pairwise atomic potential energies and forces. The results show that this interaction is associated with a mild stabilization. Since the repulsive forces are experimentally found to be weaker than those of other contacts, we conclude that also the attractive forces are weak, although in e...

Involvement of conformational isomerism in the complexity of the crystal network of 1-(4-nitrophenyl)-1H-1,3-benzimidazole derivatives driven by C-H...A (A = NO2, Npy and π) and orthogonal Npy...NO2 and ONO...Csp2 interactions.

A detailed structural analysis of the benzimidazole nitroarenes 1-(4-nitrophenyl)-1H-1,3-benzimidazole, C13H9N3O2, (I), 1-(4-nitrophenyl)-2-phenyl-1H-1,3-benzimidazole, C19H13N3O2, (II), and 2-(3-methylphenyl)-1-(4-nitrophenyl)-1H-1,3-benzimidazole, C20H15N3O2, (III), has been performed. They are nonplanar structures whose crystal arrangement is governed by Csp2-H...A (A = NO2, Npy and π) hydrogen bonding. The inherent complexity of the supramolecular arrangements of compounds (I) (Z' = 2) and (II) (Z' = 4) into tapes, helices and sheets is the result of the additional participation of π-πNO2 and n-π* (n = O and Npy; π* = Csp2 and NNO2) interactions that contribute to the stabilization of the equi-energetic conformations adopted by each of the independent molecules in the asymmetric unit. In contrast, compound (III) (Z' = 1) is self-paired, probably due to the effect of the steric demand of the methyl group on the crystal packing. Theoretical ab initio calculations confirmed that the presence of the arene ring at the benzimidazole 2-position increases the rotational barrier of the nitrobenzene ring and also supports the electrostatic nature of the orthogonal ONO...Csp2 and Npy...NO2 interactions.

DFT/TD-DFT study on the electronic and spectroscopic properties of hollow cubic and hollow spherical (ZnO) m quantum dots interacting with CO, NO2 and SO3 molecules

Hollow spherical (HS) and hollow cubic (HC) (ZnO) m quantum dots (QDs) were constructed and optimized using density functional theory (DFT) method. CO, NO2 and SO3 molecules were used to interact with the HC and HS (ZnO) m QDs at the centre and on the surface of the QDs. The changes in the electronic energy levels of HC and HS (ZnO) m QDs due to the interactions of CO, NO2 and SO3 molecules have been studied. The electronic and spectroscopic properties, such as density of states, HOMO–LUMO energy gap, absorption spectra, IR and Raman spectra of HC and HS (ZnO) m QDs have been studied using DFT and Time dependent-DFT (TD-DFT) methods. The interaction energy values show that the SO3 molecule has strongly interacted with HC and HS (ZnO) m QDs than the CO and NO2 molecules. The results of the density of states show that the HC QDs have peaks that are very close to each other, whereas the same is found to be broad in the HS QDs. The HOMO–LUMO energy gap is more for the HS QDs than the HC QDs, and also it gets decreased, when the NO2 and SO3 molecules interact at the centre of the HC and HS (ZnO) m QDs. The blue and red shifts were observed in the absorption spectra of HS and HC QDs. The natural transition orbital (NTO) plot reveals that the interaction of the molecules on the surface of the QDs reduce the chance of electron–hole recombination; hence the energy gap increases for NO2 and SO3 molecular interactions on the surface of the HC and HS (ZnO) m QDs. The vibrational assignments have been made for HC and HS QDs interacting with CO, NO2 and SO3 molecules.

π–hole interactions at work: crystal engineering with nitro-derivatives

In this manuscript, we report the design, synthesis and X-ray characterization of nitrodiene derivatives that present crucial π–hole interactions involving the nitro group as a π–hole donor. The solid state structures of 1,4-dinitro-1,3-butadiene (1), its co-crystal 1·Diox, and homologous 1,4-dinitro-1,3-pentadiene (2) and 2,4-dinitro-2,4-hexadiene (3) feature competition of lone pair–π–hole interactions with common weak CH⋯O bonding and gradually increased role of the NO2⋯NO2 interactions. Regular evolution of the supramolecular patterns (1 to 3) results in generation of an unprecedented 3D non-covalent framework in 3 that is controlled exclusively by short π–hole contacts (O⋯N = 2.9615(18), 3.1304(18) A). These findings complement the results of high level ab initio calculations (MP2/def2-TZVP) and unite theory and experiment, thus supporting the functional relevance of this novel π–hole interaction.

Efficient Conversion of Nitrogen Dioxide into Nitrous Acid on Ice Surfaces

The hydrolysis of nitrogen dioxide (NO2) on ice surfaces is studied by measuring the reaction products on the surface with the reactive ion scattering (RIS) technique, and the desorbing species is studied with temperature-programmed desorption (TPD) mass spectrometry. NO2 adsorbs molecularly on an ice film surface at a temperature of 90 K. Upon heating the film to 140 K, NO2 adsorbates are readily converted into nitrous acid (HONO), and nitrous acid products desorb intact from the surface at higher temperatures. The result indicates the efficient formation of nitrous acid gas on the ice surface with only a small activation energy. It is shown that the hydrolysis occurs from isolated NO2 adsorbates rather than through NO2−NO2 interactions. The implications of these findings for the atmospheric heterogeneous reaction of NO2 are mentioned.

NMR studies of the chalcogen analogues of benzofuran. IV—Proton, carbon‐13 and selenium‐77 magnetic resonance in nitrobenzo[b]selenophenes

AbstractThe 1H, 13C and 77Se chemical shifts have been measured for mononitrobenzo[b]selenophenes. For the homocyclic nuclei, the observed 1H‐ and 13C‐values calculated from the empirical increments of nitrobenzene. Anomalous effects are observed in the 2‐ and 3‐substituted derivatives and the nature of the SeNO2 interactions in the former is discussed. 77Se chemical shifts of the 4‐, 5‐ and 7‐nitro derivatives are approximately correlated with the CNDO calculated electron densities; they also compare well with those of selenoanisoles and other phenyl alkyl selenides. The chemical shifts are also compared with the corresponding values in other heterocycles containing a selenophene moiety.