Number Of Aromatic Rings Research Articles

Ferrocenyl β-Diketonate Compounds: Extended Ring Systems for Improved Anticancer Activity.

A library of ferrocenyl β-diketonate compounds with varying degrees of aromatic functionality have been synthesized and fully characterized. This includes cyclic voltammetry and the analysis of four new structures by single crystal X-ray diffraction. The compounds cytotoxic potential has been determined by MTT screening against pancreatic carcinoma (MIA PaCa-2), ovarian adenocarcinoma (A2780), breast adenocarcinomas (MDA-MB-231 and MCF-7) and normal epithelial retinal (ARPE-19). The compounds show a general trend, where increasing the number of aromatic rings in the molecule yields an increase in cytotoxicity and follows the trend anthracenyl > naphthyl > phenyl > methyl. The compounds are particularly sensitive to the triple negative cancer cell line MDA-MB-231, and the potential modes of action have been studied by production of reactive oxygen species using fluorescence microscopy and cell morphology using Scanning Electron Microscopy. All assays highlight the ferrocenyl β-diketonate with an anthracenyl substituent to be the lead compound in this library. The decomposition was also observed within cells, to give a cytotoxic fluorescent molecule, which has been visualized by confocal microscopy.

Structural parameters and molecular model of Shendong subbituminous coal

Coal has a highly complex chemical structure, similar to polymers, coal is a macromolecular structure composed of a large number of “similar compounds”, which is called the basic structural unit. Understanding coal structure is the basis of its transformation and utilization. Shendong (SD) coal was analyzed by FTIR, XRD, XPS, and NMR. The results show that SD coal normalized structure formula is C100H68.5O35.7N1.2S0.2 and the average number of aromatic rings is 1.98. –CH2— content accounts for about 82% in aliphatic C–H region, and the ratio of ether bond C–O, aromatic ether C–O and CO is about 2:1:11 in oxygen-containing functional group region. The d002, LC, La and NC of SD coal microcrystalline structure parameters are 0.1832 nm, 1.4688 nm, 2.0852 nm and 9.017, respectively. Aromatic carbon and aliphatic carbon ratios of SD coal are 55.67% and 29.97%, aromatic cluster size and average methylene chain length are 0.224 and 1.817. Based on these structural parameters, molecular model of SD coal was constructed with 13C SSNMR experimental spectra as a reference. The model was constructed with an atom composition of C214H214O49N2S.

Assessment of the contamination by carbonaceous anthropogenic particulates and polycyclic aromatic hydrocarbons (PAHs) concentration in recreational areas of an estuary heavily industrialized in Northern Spain

The commercial management of coal and its by-products has the potential to negatively impact natural coastal environments. The coal conversion processes and coke production are sources of polycyclic aromatic hydrocarbons (PAHs) emissions that also contribute to the pollution of those aquatic environments. This research assesses the contamination by carbonaceous anthropogenic particles and by polycyclic aromatic hydrocarbons of some recreational sites (Arañón, Peña del Caballo and San Balandrán area) located in the Avilés' estuary, an area in Northern Spain that has been heavily industrialized since the 1950s. The results obtained indicate a low concentration of solid organic anthropogenic particles in the intertidal sediments of the recreational sites in the estuary, probably due to the protective measures set in place at the facilities managing bulk coal and coke, which prevents the dispersion of coal dust (and other materials) as well as the eventual failure into the estuary. The characteristics of 16 priority pollutants PAHs analyzed in two recreational sites of the estuary (San Balandrán area), their distribution by aromatic ring number together with their diagnostic ratios demonstrate a pyrogenic nature with a main source from processes of coal and coke conversion (including combustion) in the facilities around the estuary. Some contribution of PAHs derived from petroleum cannot be ruled out. This contamination by PAHS is constant and sustained over time. The majority of the considered PAHs are well above the Spanish Generic Reference Level, (GRL) established for “protection of ecosystems with aquatic organisms”, and only a few of them are notably above the corresponding Spanish GRL established for “other uses of land”, which should include lands for recreational activities. The analysis of the potential toxicity risk of PAHs for human health and the organisms of the aquatic ecosystem suggests a relatively low toxicity risk to very high toxicity risk in the San Balandrán environment according to the concentration and distribution trend of PAHs identified in this area. This trend is dependent on the coastal dynamics and the protection level of the site, which also affect the distribution of the anthropogenic carbonaceous particulates in the same way.

Insight into carbon structures and pyrolysis behaviors of coal from the 13C CP/MAS NMR spectra

Carbon structures play an important role in the pyrolysis behavior of coal. Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy is a powerful nondestructive technique for characterizing the carbon skeleton structures in coal. In this study, the carbon type distribution, lattice parameters, and chemical bond concentrations of six coal samples with different Vdaf values were investigated using 13C CP/MAS NMR spectra. Typical TGA and Py-GC-MS methods were utilized to obtain information on weight loss and pyrolysis products of the coals. The aromaticity of coal was determined by an adjustment of the apparent area ratio in the 13C CP/MAS NMR spectra, which shows promising potential for predicting key temperatures, characteristic index, and tar quality in coal pyrolysis. Results from the carbon fractions indicated that the total concentrations of chemical bonds in coal are approximately 150 mmol/g, with more Car−Car and Car−H bonds present in highly mature coal samples, and fewer Cal−Cal, Cal−H, and CO bonds. The breaking behaviors of chemical bonds during coal pyrolysis depend on a combination of temperature and concentration. The breakage of Cal−Cal bond contributes significantly to the pyrolytic weight loss of coal, accompanied by the decrease of Cal−H bonds along with the removal of aliphatic groups. Furthermore, as coal maturity increases, tar from fast pyrolysis contains more polycyclic aromatic hydrocarbons with a higher average molecular weight. The average number of aromatic rings in tar components is notably lower than that of aromatic clusters in coal. These results will contribute to a better understanding of the relationship between coal structure and reactivity, and may provide valuable insights for the efficient and clean utilization of coal.

Towards efficient Ir(III) anticancer photodynamic therapy agents by extending π-conjugation on N^N ligands.

In this work we disclose a new family of biscyclometallated Ir(III) complexes of the general formula [Ir(C^N)2(N^N)]Cl (IrL1-IrL5), where HC^N is 1-phenyl-β-carboline and N^N ligands (L1-L5) are different diimine ligands that differ from each other in the number of aromatic rings fused to the bipyridine scaffold. The photophysical properties of IrL1-IrL5 were thoroughly studied, and theoretical calculations were performed for a deeper comprehension of the respective variations along the series. All complexes exhibited high photostability under blue light irradiation. An increase in the number of aromatic rings led to a reduction in the HOMO-LUMO band gap causing a red-shift in the absorbance bands. Although all the complexes generated singlet oxygen (1O2) in aerated aqueous solutions through a photocatalytic process, IrL5 was by far the most efficient photosensitizer. Consequently, IrL5 was highly active in the photocatalytic oxidation of NADH. The formation of aggregates in DMSO at a high concentration (25 mM) was confirmed using different techniques, but was proved to be negligible in the concentration range of biological experiments. Moreover, ICP-MS studies proved that the cellular uptake of IrL2 and IrL3 is much better relative to that of IrL1, IrL4 and IrL5. The antiproliferative activity of IrL1-IrL5 was investigated in the dark and under blue light irradiation against different cancer cell lines. Complexes IrL1-IrL4 were found to be cytotoxic under dark conditions, while IrL5 turned out to be weakly cytotoxic. Despite the low cellular uptake of IrL5, this derivative exhibited a high increase of cytotoxicity upon blue light irradiation resulting in photocytotoxicity indexes (PI) up to 38. IrL1-IrL4 showed lower photocytotoxicity indexes ranging from 1.3 to 17.0. Haemolytic experiments corroborated the compatibility of our complexes with red blood cells. Confocal microscopy studies proved their accumulation in mitochondria, leading to mitochondrial membrane depolarization, and ruled out their localization in lysosomes. Overall, the mitochondria-targeted activity of IrL5, which inhibits considerably the viability of cancer cells upon blue light irradiation, allows us to outline this PS as a new alternative to traditional chemotherapeutic agents.

Impact of deodorisation time and temperature on the removal of different MOAH structures: a lab-scale study on spiked coconut oil

Vegetable fats and oils are prone to contamination by mineral oil hydrocarbons due to the lipophilic and ubiquitous character of the latter. As the aromatic fraction of these hydrocarbons, MOAH, is associated with carcinogenicity, mutagenicity, and detrimental effects on foetal development, finding strategies to limit or reduce their contamination is highly relevant. Deodorisation (i.e. a refining step) has shown the ability to remove MOAH < C25 in vegetable fats and oils, but there is little information about the structures removed. Therefore, the present study investigated the impact of deodorisation conditions on the removal of different structures of MOAH in spiked coconut oil. An inscribed central composite design was built with time and temperature as variables (0.5-4h, 150-240 °C), while pressure (3 mbar) and steam flow (1 g water/g oil per hour) were kept constant. The analysis of MOAH in the oil was performed using a fully automated liquid chromatography coupled with two parallel comprehensive two-dimensional gas chromatography systems with flame ionisation and time-of-flight mass spectrometric detection. Response surfaces plotting the MOAH loss according to time and temperature were built for different MOAH fractions. The latter were defined based on the number of aromatic rings (>3 or ≤3) and the number of carbon atoms present (C16-C20, C20-C24, C24-C35, C35-C40). It was found that at 200 °C, compounds < C24, including weakly alkylated triaromatics, could be reduced to below the limit of quantification, while at 230 °C, it was possible to remove >60% of the C24-C35 fraction, including pentaromatics of low alkylation.

Predictions of biorelevant solubility change during dispersion and digestion of lipid-based formulations

Computational approaches are increasingly explored in development of drug products, including the development of lipid-based formulations (LBFs), to assess their feasibility for achieving adequate oral absorption at an early stage. This study investigated the use of computational pharmaceutics approaches to predict solubility changes of poorly soluble drugs during dispersion and digestion in biorelevant media. Concentrations of 30 poorly water-soluble drugs were determined pre- and post-digestion with in-line UV probes using the MicroDISS Profiler™. Generally, cationic drugs displayed higher drug concentrations post-digestion, whereas for non-ionized drugs there was no discernible trend between drug concentration in dispersed and digested phase. In the case of anionic drugs there tended to be a decrease or no change in the drug concentration post-digestion. Partial least squares modelling was used to identify the molecular descriptors and drug properties which predict changes in solubility ratio in long-chain LBF pre-digestion (R2 of calibration = 0.80, Q2 of validation = 0.64) and post-digestion (R2 of calibration = 0.76, Q2 of validation = 0.72). Furthermore, multiple linear regression equations were developed to facilitate prediction of the solubility ratio pre- and post-digestion. Applying three molecular descriptors (melting point, LogD, and number of aromatic rings) these equations showed good predictivity (pre-digestion R2 = 0.70, and post-digestion R2 = 0.68). The model developed will support a computationally guided LBF strategy for emerging poorly water-soluble drugs by predicting biorelevant solubility changes during dispersion and digestion. This facilitates a more data-informed developability decision making and subsequently facilitates a more efficient use of formulation screening resources.

Structure-based modeling to assess binding and endocrine disrupting potential of polycyclic aromatic hydrocarbons in Daniorerio

Environmental contaminants, such as polycyclic aromatic hydrocarbons (PAHs), have raised concerns regarding their potential endocrine-disrupting effects on aquatic organisms, including fish. In this study, molecular docking and molecular dynamics techniques were employed to evaluate the endocrine-disrupting potential of PAHs in zebrafish, as a model organism. A virtual screening with 72 PAHs revealed a correlation between the number of PAH aromatic rings and their binding affinity to proteins involved in endocrine regulation. Furthermore, PAHs with the highest binding affinities for each protein were identified: cyclopenta[cd]pyrene for AR (−9.7 kcal/mol), benzo(g)chrysene for ERα (−11.5 kcal/mol), dibenzo(a,e)pyrene for SHBG (−8.7 kcal/mol), dibenz(a,h)anthracene for StAR (−11.2 kcal/mol), and 2,3-benzofluorene for TRα (−9.8 kcal/mol). Molecular dynamics simulations confirmed the stability of the protein-ligand complexes formed by the PAHs with the highest binding affinities throughout the simulations. Additionally, the effectiveness of the protocol used in this study was demonstrated by the receiver operating characteristic curve (ROC) analysis, which effectively distinguished decoys from true ligands. Therefore, this research provides valuable insights into the endocrine-disrupting potential of PAHs in fish, highlighting the importance of assessing their impact on aquatic ecosystems.

Non‐Covalent Functionalization of Magnetic Carbon Nanotubes with Fmoc Amino Acid‐Modified Polyethylene Glycol

AbstractOnce dispersion and cytotoxicity issues are resolved, it has been proven that carbon nanotubes (CNTs) have great advantages in biomedical applications due to their unique properties. In this study, the superiority of carbon nanotubes was combined with magnetic targeting strategies, and a solution to the distribution problem in the aqueous media of the resulting CNTs decorated with iron oxide (mCNTs) was sought. A non‐covalent functionalization approach has been utilized to overcome this fundamental drawback of mCNTs. Conjugates of polyethylene glycol monomethyl ether and 9‐ fluorenyl methyl chloroformate (Fmoc) amino acids were used to coat the lateral surfaces of mCNTs, making them more water‐soluble. The selected Fmoc amino acids have different numbers of aromatic rings, which is known to affect the coating efficiency in non‐covalent functionalization and therefore, the dispersion behavior of the CNTs. Their coating yields, dispersion behaviors, magnetism, charge, and size properties have been determined. All coated mCNT samples displayed superparamagnetic behavior. Dispersion tests showed a promise to increase the stability of mCNTs with this approach. Moreover, we demonstrated that the functionalization of mCNTs affects cell viability in a dose‐dependent manner. The main finding of this study is that mCNTs can be successfully functionalized with Fmoc amino acid‐modified polyethylene glycol.

Three distinct conductance states in polycyclic aromatic hydrocarbon derivatives.

Tight-binding model (TBM) and density functional theory (DFT) calculations were employed. Both simulations have demonstrated that the electrical conductance for eight polycyclic aromatic hydrocarbons (PAHs) can be modulated by varying the number of aromatic rings (NAR) within the aromatic derivatives. TBM simulations reveal three distinct conductance states: low, medium and high for the studied PAH derivatives. The three distinct conductance states suggested by TBM are supported by DFT transmission curves, where the low conductance evidenced by T(E) = 0, for benzene, naphthalene, pyrene and anthracene. While azulene and anthanthrene exhibit a medium conductance as T(E) = 1, and tetracene and dibenzocoronene possess a high conductance with T(E) = 2. Low, medium and high values were elucidated according to the energy gap E g and E g gaps are strongly dependent on the NAR in the PAH derivatives. This study also suggests that any PAH molecules are a conductor if E g < 0.20 eV. A linear relationship between the conductance and NAR (G ∝ NAR) was found and conductance follows the order G (benzene, 1 NAR) < G (anthanthrene, 4 NAR) < G (dibenzocoronene, 9 NAR). The proposed study suggests a relevant step towards the practical application of molecular electronics and future device application.

Tribological properties of polyaromatic organics as lubricating grease

The tribological properties of polyaromatic organics (xPyE) as lubricating grease additives are studied by simulations and experiments. Molecular Dynamics (MD) simulations are used to simulate the mechanical properties of four kinds of polyaromatic organics (2P1E, 3P2E, 4P3E, and 5P4E) with different aromatic ring numbers and a mass fraction under 300 MPa and 5 m/s relative shear velocity of the two solid walls. The friction force, positive pressure, stress, and adsorption energy are calculated quantitatively. Meantime, the friction coefficient of lubricating grease and the wear morphology of the sample are measured by Multifunctional Friction and Wear Testing Machine. The results show that the organic additives adsorbed on the wall form a protective film during the shearing process, improving the bearing capacity and reducing friction and wear. Among them, the 3P2E organic additive has an appropriate number of aromatic rings. Its single molecular adsorption energy and unit adsorption energy are higher than other organic additives and can uniformly lay on the wall to form a stable, protective film. This demonstrates the best friction performance and improves the load-bearing capacity of the lubricating film, reducing maximum wall stress by 53.4 %.

Theoretical analysis of hydrogen solubility in direct coal liquefaction solvents

The cyclic hydrogenation technology in a direct coal liquefaction process relies on the dissolved hydrogen of the solvent or oil participating in the hydrogenation reaction. Thus, a theoretical basis for process optimization and reactor design can be established by analyzing the solubility of hydrogen in liquefaction solvents. Experimental studies of hydrogen solubility in liquefaction solvents are challenging due to harsh reaction conditions and complex solvent compositions. In this study, the composition and content of liquefied solvents were analyzed. As model compounds, hexadecane, toluene, naphthalene, tetrahydronaphthalene, and phenanthrene were chosen to represent the liquefied solvents in chain alkanes and monocyclic, bicyclic, and tricyclic aromatic hydrocarbons. The solubility of hydrogen X (mol/mol) in pure solvent components and mixed solvents (alkanes and aromatics mixed in proportion to the chain alkanes + bicyclic aromatic hydrocarbons, bicyclic saturated aromatic hydrocarbons + bicyclic aromatic hydrocarbons, and bicyclic aromatic hydrocarbons + compounds containing heteroatoms composed of mixed components) are determined using Aspen simulation at temperature and pressure conditions of 373–523 K and 2–10 MPa. The results demonstrated that at high temperatures and pressures, the solubility of hydrogen in the solvent increases with the increase in temperature and pressure, with the pressure having a greater impact. Furthermore, the results revealed that hydrogen is more soluble in straight-chain alkanes than in other solvents, and the solubility of eicosanoids reaches a maximum of 0.296. The hydrogen solubility in aromatic ring compounds decreased gradually with an increase in the aromatic ring number. The influence of chain alkanes on the solubility of hydrogen predominates in a mixture of solvents with different mixing ratios of chain alkanes and aromatic hydrocarbons. The solubility of hydrogen in mixed aromatic solvents is less than that in the corresponding single solvents. Hydrogen is less soluble in solvent compounds containing heteroatoms than in compounds without heteroatoms.

Energy gap and aromatic molecular rings.

The manuscript combines rational density functional theory simulations and experimental data to investigate the electrical properties of eight polycyclic aromatic hydrocarbons (PAHs). The optimized geometries reveal a preference for one-row, two-row and three-row ring distributions. Band structure plots demonstrate an inverse correlation between the number of aromatic rings and band gap size, with a specific order observed across the PAHs. Gas phase simulations support these findings, though differences in values are noted compared to the literature. Introducing a two-row ring distribution concept resolves discrepancies, particularly in azulene. The B3LYP function successfully bridges theoretical and experimental gaps, particularly in large PAHs. The manuscript highlights the potential for designing electronic devices based on different-sized PAHs, emphasizing a multi-ring distribution approach and opening new avenues for practical applications.

Poly(ester imide)s with Low Linear Coefficients of Thermal Expansion and Low Water Uptake (VII): A Strategy to Achieve Ultra-Low Dissipation Factors at 10 GHz.

In this study, a series of ester-linked tetracarboxylic dianhydrides (TCDAs) with 2,6-naphthalene-containing longitudinally extended structures consisting of different numbers of aromatic rings (NAr = 6-8) was synthesized to obtain novel modified polyimides, poly(ester imide)s (PEsIs). These TCDAs were fully compatible with the conventional manufacturing processes of conventional polyimide (PI) systems. As an example, the PEsI film obtained from the ester-linked TCDA (NAr = 8) and an ester-linked diamine achieved unprecedented outstanding dielectric properties without the support of fluorinated monomers, specifically an ultra-low dissipation factor (tan δ) of 0.00128 at a frequency of 10 GHz (50% RH and 23 °C), in addition to an extremely high glass transition temperature (Tg) of 365 °C, extremely low linear coefficient of thermal expansion (CTE) of 6.8 ppm K-1, suppressed water uptake (0.24%), requisite film ductility, and a low haze. Consequently, certain PEsI films developed in this study are promising candidates for heat-resistant dielectric substrates for use in 5G-compatible high-speed flexible printed circuit boards (FPCs). The chemical and physical factors denominating tan δ are also discussed.

Examining diverse remediation mechanisms of biochar in soil contaminated with polycyclic aromatic hydrocarbon (PAH) of various ring structures: A global meta-analysis

Biochar is a widely recognized solution for addressing polycyclic aromatic hydrocarbon (PAH) contamination. However, it is unclear how the different physicochemical properties of PAHs affect remediation mechanisms, thereby affecting the remediation efficiency of biochar. In this study, a meta-analysis of 56 studies with 2236 observations was conducted to quantify the contributions of the preparation parameters and physicochemical properties of biochar, soil properties, and application measures to remediation efficiency. The research results revealed that PAH contents in the contaminated soil were significantly reduced by an average of 24.99 % after the application of biochar. Random Forest analysis identified feedstock, biochar SSA, soil pH, and rate of biochar application to be the most critical factors among the four categories. The reduction of PAH contents in the contaminated soil first decreased from 37.61 % to 17.44 % and then increased to 40.29 % with an increase in the number of aromatic rings from 2 to 6. Our study results suggest that biochar prepared from bio-waste at low temperatures could be favorable for reducing the content of NAP in soil. Wood-derived biochar pyrolyzed at a relatively high temperature is recommended for remediation of soil contaminated with PAHs with 5 or 6 aromatic rings. Our study provides a new perspective and an optimized strategy for the remediation of PAH-contaminated soils with biochar.

Anthracene-based dual channel donor-acceptor triazine-containing covalent organic frameworks for superior photoelectrochemical sensing

Covalent organic frameworks (COFs) exhibit excellent photoelectrically active structures and serve as channels for photon capture and charge carrier transport. However, their relatively high charge-carrier recombination rates and lack of specific recognition sites limit their application in photoelectrochemical sensing. This paper reports a functionalized donor–acceptor (D-A) COF comprising electron-rich polycyclic aromatic moieties and electron-deficient triazines (Tz) incorporating boronic acid through ligand exchange. The number of aromatic rings in the polycyclic aromatic moiety is crucial for establishing an efficient D-A system within COF. In the absence of an external electron donor, the anthracene-based COF exhibited a five-fold enhancement in photocurrent compared to the naphthalene-based COF. The resulting anthracene-based D-A COF exhibited enhanced orbital overlap and electron push–pull interactions, facilitating more effective charge separation. Furthermore, introducing boronic acid enabled the selective enrichment of low-concentration external electron donors, such as dopamine, in the inner Helmholtz plane. This ingenious approach establishes a unique dual-channel D-A system that allows direct measurement of dopamine in serum. Under optimized conditions, the test platform achieves good correspondence for dopamine at 1 to 100 nM and 0.5 to 100 μM with a detecting limit of 0.36 nM (3σ/S, n = 11). This strategy introduces a novel dimension to photoelectrochemical sensing, focusing on the effect of spatial separation between the external electron donor and the photoelectrode interface that intricately shapes the behavior and enhances the performance of the photoelectric system.

Advanced separation of mineral oil aromatic hydrocarbons by number of aromatic rings using donor-acceptor-complex chromatography to extend on-line coupled liquid chromatography-gas chromatography

An automated implementation for a subfractionation of mineral oil aromatic hydrocarbons (MOAH) into a mono-/di-aromatic fraction (MDAF) and a tri-/poly-aromatic fraction (TPAF) is presented, which is highly demanded by the European Food Safety Authority (EFSA) respecting the genotoxic and carcinogenic potential of MOAH. For this, donor-acceptor-complex chromatography (DACC) was used as a selective stationary phase to extend the conventional instrumental setup for the analysis of mineral oil hydrocarbons via on-line coupled liquid chromatography-gas chromatography-flame ionization detection (LC-GC-FID). A set of six new internal standards was introduced for the verification of the MOAH fractionation and a quantification of MDAF and TPAF, respectively. The automated DACC approach was applied to representative petrochemical references as well as to food samples, such as rice and infant formula, generally showing well conformity with results obtained by state-of-the-art analysis using two-dimensional GC (GCxGC). Relative deviations of DACC/LC-GC-FID compared to GCxGC-FID methods regarding the ≥ 3 ring MOAH content ranged between -50 and +6 % (median: -2 %, all samples, only values above limit of quantification). However, crucial deviations mainly result from “border-crossing” substances, e.g., dibenzothiophenes or partially hydrogenated MOAH. These substances can cause overestimations of ≥ 3 ring MOAH fraction during GCxGC analysis due to co-elution, which is mostly avoided using the DACC approach. Furthermore, the DACC approach can help to minimize underestimations of toxicologically relevant ≥ 3 ring MOAH caused by an unavoidable loss of MOAH during epoxidation, since natural olefins, such as terpenes, predominantly elute in MDAF, which was exemplarily shown for an olive oil and a terpene reference. The presented approach can be implemented easily in existing LC-GC-FID setup for an automated and advanced screening of MOAH to lower the need for elaborate GCxGC analysis also in routine environments.

Synthesis and characterization of 1,2,3,4-naphthalene and anthracene diimides.

We report the synthesis and characterization of naphthalene and anthracene scaffolds end-capped by cyclic imides. The solid-state structures of the N-phenyl derivatives, determined by X-ray crystallography, reveal changes in packing preference based on the number of aromatic rings in the core. The optical and electronic properties of the title compounds compare favorably with other previously described isomers and expand the toolbox of electron-deficient aromatic compounds available to organic materials chemists.

In-depth understanding of the microscopic mechanism of biochar carbonaceous structures during thermochemical conversion: Pyrolysis, combustion and gasification

The thermochemical utilization of biomass char is vital for addressing environmental pollution and the energy crisis. The carbonaceous structure plays a crucial role in this process, and understanding the conversion mechanism aids in optimizing biomass reactors. This study performs a comprehensive analysis of high-temperature rice husk char using 13C NMR, XPS, and FTIR techniques. The carbonaceous structure is classified based on carbon bonding modes and the forms of O and N. The reaction mechanisms of thermochemical transformations under various atmospheres (N2, O2, CO2, H2O) are investigated using ReaxFF-MD. The reaction characteristics are determined, and the reaction activities are compared. The results indicate that the nitrogen-containing heterocycles remain in pyridine-type pyrolysis products under the N2 atmosphere (pyrolysis). Repolymerization occurs in the initial stages of pyrolysis, with the size of aromatic rings affecting the formation of heavy components. Under the O2 atmosphere (combustion), the degree of complete carbon oxidation is linked to the number of aromatic rings. The reactivity of aliphatic carbonaceous structures depends on the hydrogen content. Under the CO2 atmosphere (gasification), the pyrrole-type structure exhibits the highest gasification activity. Aromatic structures with oxygen functional groups are more susceptible to reacting with CO2, indicating higher sensitivity. Aliphatic H atoms tend to be oxidized into H2O. Under the H2O atmosphere (gasification), hydrogen in the gasification of aromatic carbon primarily originates from H at the aromatic boundary. In N2 and CO2 atmospheres, the CO bridge bond breaks first, followed by reactions. In H2O gasification, the breaking of bridge bonds connected to aliphatic carbon occurs simultaneously with gasification. Each reaction system's product distribution and elemental migration processes are also determined. The findings provide valuable theoretical insights into the application of biomass char.

Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons.

Reactive molecular dynamics simulations are used to model the covalent functionalization of amorphous silica with aromatic hydrocarbons. Simulations show that the surface density of silanol-terminated phenyl, naphthyl, and anthracenyl molecules is lower than the maximum value calculated based on molecule geometry, and the simulation densities decrease faster with the number of aromatic rings than the geometric densities. The trends are analyzed in terms of the surface-silanol bonding configurations, tilt angles, local conformational ordering, and aggregation of surface-bound molecules under steady-state conditions. Results show that the surface density is affected by both the size and symmetry of the aromatic hydrocarbons. The correlations among bonding, orientation, and surface density identified here may guide the selection or design of molecules for functionalized surfaces.