Nitrogen Research Articles

Experimental Charge Density Study of Hypersilyl Sulfur Diimide

AbstractIn here three newly synthesized silyl substituted sulfur diimides S(NSi(SiMe3)3)2 (2), S(NSi(NMe2)3)2 (3) and S(NSiHiPr2)2 (4) are presented. 2 is characterised by experimental charge density investigations and compared to the di‐tert‐butyl sulfur diimide S(NtBu)2 (1). While the silylation seems not to have much impact on the sulfur‐nitrogen bonding the increase of negative charge at the nitrogen atoms is obvious. Hence, the silylated molecules should be better donors in metal chelation, provided the change from the genuine E/Z conformation to E/E is facilitated. Indeed, their calculated free energy gaps between initial and transition states, related to the rotation of the silyl substituted derivatives 2–4, interestingly found via different rearrangements, turned out to be only a third of that of 1, despite of changing the substituents linked to the Si atoms. This is due to the longer and more polar N−Si bonds compared to the N−C bonds.

A Scorpion–Type Dopant‐Free Hole Transport Material for n‐i‐p Organic–Inorganic Hybrid Perovskite Solar Cells

AbstractIt is significant to develop dopant‐free hole transport materials (HTMs) to improve the long‐term stability of n‐i‐p organic–inorganic hybrid perovskite solar cells (PSCs). In this work, two HTMs (DTTP‐T and DTTP‐D) based on dithienothiopyrrole (DTTP) core were synthesized to explore the effects of different substituents on the nitrogen atom on the properties of HTMs. Compared with anisole‐substituted DTTP‐D, triarylamine‐substituted scorpion‐type DTTP‐T shows better matching energy level, stronger charge transfer and defect passivation ability. Therefore, the power conversion efficiency (PCE) of dopant‐free DTTP‐T‐based n‐i‐p PSCs reaches 18.67 %, which is comparable to that of doped Spiro‐OMeTAD (19.51 %). More encouragingly, the efficiency of DTTP‐T‐based devices remains above 80 % of its initial efficiency after 1728 h of storage in air, while the Spiro‐OMeTAD‐based devices could only maintain 600 h. This work provides a good reference for the development of dopant‐free small molecular HTMs for efficient and stable PSCs.

Synthesis and Structure of Rhenium and Manganese Carbonyl Complexes Bearing a Thiosaccharinate Ligand

AbstractThe reactions of [M2(CO)8(NCMe)2] (M=Re, Mn) with thiosaccharin (tsacH) have been investigated. TsacH reacts with [Re2(CO)8(NCMe)2] at room temperature to furnish [Re2(CO)8(μ‐H)(μ‐sac‐κN,S)] (1) and [Re(CO)5(sac‐κS)] (2), while a similar reaction with [Mn2(CO)8(NCMe)2] affords only [Mn(CO)5(sac‐κS)] (3). The dinuclear 1 contains a bridging tsac ligand coordinated to both rhenium centers using the nitrogen and thiocarbonylic sulfur atoms, while the tsac ligand is bonded to the metal center only through the sulfur atom in mononuclear 2 and 3. The molecular structures of 1–3 have also been determined by X‐ray crystallography.

Organic‐Based Chemiresistive Sensors for Detection of Water‐Soluble Gases: Strategies and Roadmap for Enhancing Sensing Performance

AbstractTraditional organic‐based chemiresistive sensors have been a key area of research due to their portability, low power consumption, low cost, turnability, and possibility for miniaturization. However, their real‐world applications have remained restricted by their low selectivity, low sensitivity, and low stability under demanding conditions, such as extreme temperature, humidity, and pH. As such, this review aims to lay the foundation for enhancing the performance of these gas sensors via chemical and physical modifications. To this end, an insight into the building blocks of chemiresistive gas sensors and the attributes of the main four gases (ammonia, carbon dioxide, hydrogen sulfide, and nitrogen dioxide) under aqueous conditions are provided. Such features ultimately determine the enhancement strategy that is best suited to improve the chemiresistive gas sensors performance. Furthermore, this article provides an outlook into the current bottleneck in sensor development and its translation from lab to end‐consumer use. Overall, this review aims to serve as a roadmap for developing next‐generation, high performing chemiresistive gas sensors.

A unicellular cyanobacterium relies on sodium energetics to fix N2

Diazotrophic cyanobacteria can fix nitrogen gas (N2) but are usually scarce in nitrogen-limited coastal waters, which poses an apparent ecological paradox. One hypothesis is that high salinities (> 10 g/L NaCl) may inhibit cyanobacterial N2 fixation. However, here we show that N2 fixation in a unicellular coastal cyanobacterium exclusively depends on sodium ions and is inhibited at low NaCl concentrations (< 4 g/L). In the absence of Na+, cells of Cyanothece sp. ATCC 51142 (recently reclassified as Crocosphaera subtropica) upregulate the expression of nifHDK genes and synthesise a higher amount of nitrogenase, but do not fix N2 and do not grow. We find that the loss of N2-fixing ability in the absence of Na+ is due to insufficient ATP supply. Additional experiments suggest that N2 fixation in this organism is driven by sodium energetics and mixed-acid fermentation, rather than proton energetics and aerobic respiration, even though cells were cultured aerobically. Further work is needed to clarify the underlying mechanisms and whether our findings are relevant to other coastal cyanobacteria.

Crystal structures of two polymorphs for fac-bromidotricarbonyl[4-(4-methoxyphenyl)-2-(pyridin-2-yl)thiazole-κ2 N,N′]rhenium(I)

Crystallization of the title compound, fac-[ReBr(ppt-OMe)(CO)3] (ppt-OMe = C15H12N2OS), from CH2Cl2/n-pentane (1:5 v/v) at room temperature gave two polymorphs, which crystallize in monoclinic (P21/c; α form) and orthorhombic (Pna21; β form) space groups. The ReI complex molecules in either polymorph adopt a six-coordinate octahedral geometry with three facially-oriented carbonyl ligands, one bromido ligand, and two nitrogen atoms from one chelating ligand ppt-OMe. In the crystal, both polymorph α and β form di-periodic sheet-like architectures supported by multiple hydrogen bonds. In polymorph α, two types of hydrogen bonds (C—H...O) are found while, in polymorph β, four types of hydrogen bonds (C—H...O and C—H...Br) exist.

O- and N-Difluoromethylation of 2-Pyridones with Chlorodifluoromethane

Difluoromethylation of various 2-pyridones with the available industrial reagent chlorodifluoromethane (Freon-22) has been studied. Some relationships between the ratio of difluoromethylation products and the reaction conditions, as well as the presence of substituents in the pyridine ring, have been found. The possibility of obtaining difluoromethylation products at the nitrogen atom, in some cases with a preparative yield, has been investigated.

Synthesis, Chiroptical Properties, and Absolute Configuration Determination of Phenyl‐4‐pyridyl‐2,5‐dipyrimidinylmethane

Phenyl‐4‐pyridyl‐2,5‐dipyrimidinylmethane (1) has been synthesized in five steps from 5‐methylpyrimidine. The structural feature of 1 is the symmetry elements with respect to the 180º rotation of the aryl group along the central C‐C bonds. Due to this structural feature, the compound 1 is expected the good crystallinity despite of the asymmetric molecular structure. The optical resolution of 1 was achieved by high performance liquid chromatography using chiral stationary phase (chiral HPLC). The circular dichroism (CD) spectra of the two fractions showed opposite signs. As expected, the X‐ray crystallographic analysis was successfully performed for both the racemic and enantiomerically pure crystals of compound 1, with the nitrogen atoms being unambiguously assigned in both cases. It was concluded the first‐eluted fraction in chiral HPLC was determined to be S configuration both by the CD calculation for reproducing the experimental CD spectrum and by the anomalous diffraction of X‐ray crystallographic analysis of enantiomerically pure 1.

Valuable Ca/P Sources Obtained from Tuna Species’ By-Products Derived from Industrial Processing: Physicochemical and Features of Skeleton Fractions

The global tuna canning industry generates substantial volumes of by-products, comprising 50% to 70% of the total processed material. Traditionally, these by-products have been utilized in low-value products such as fish oils and fishmeal. However, there is significant potential to extract high-value compounds from these by-products, such as calcium phosphates (CaP), which can have pharmaceutical, agricultural and biotechnological applications. This work explores the potential of tuna canning by-products, particularly mineral-rich fractions (central skeleton, head and fish bones) as sources of calcium phosphates (CaP), offering a sustainable alternative to conventional synthetic derivatives within a circular bioeconomy framework. By-products from two of the most exploited species (yellowfin and skipjack) were subjected to enzymatic hydrolysis and chemical extraction, followed by controlled calcination to obtain CaP. The content of organic matter, nitrogen, total proteins, lipids and amino acids in the cleaned bones, as well as the main chemical bonds, structure and elemental composition (FT-Raman, XRD, XRF) were evaluated. Results indicated that the highest recovery yield of wet bones was achieved using the chemical method, particularly from the dorsal and caudal fins of yellowfin tuna. The proximal composition, with ash content ranging from 52% to 66% and protein content varying between 30% and 53%, highlights the potential of tuna skeleton substrates for plant growth formulations. Furthermore, variations in crystalline structures of the substrates revealed significant differences depending on the by-product source and species. XRD and Raman results confirmed a monophase calcium phosphate composition in most samples from both species, primarily based on hydroxyapatite (central skeleton, caudal and dorsal fin) or whitlockite/β-tricalcium phosphate (viscera), whereas the heads exhibited a biphasic composition. Comparing the species, yellowfin tuna (YF) exhibited a hydroxyapatite structure in the branchial arch and scales, while skipjack (SKJ) had a biphasic composition in these same regions.

Research on the pharmacological potential of 1-alkyl derivatives of 3,5-dimethyl-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide

The heterocyclic system of 1,2,4-triazole and its derivatives is one of the leaders in the development of highly promising biologically active compounds. The peculiarities of the chemical structure of the derivatives of this heterocycle provide a wide range of possibilities for chemical transformations that allow to obtain really effective drugs. The involvement of several substituents in chemical transformations simultaneously, which have the properties of highly reactive centers, additionally creates favorable conditions for the formation of rational ways to create a biologically active compound. Amino-, mercapto- or hydroxogroups often play the role of such groups in chemistry. The use of these groups as substituents of 1,2,4-triazole synthon provides multifaceted opportunities for directed chemical transformation. The ability of such structural fragments to form chemical interactions and bonds with biological targets has an additional positive effect in the sense of their involvement in chemical transformations on the way to the targeted production of a biologically active substance. Thus, the combination of a heterocyclic structure with a highly reactive chemical center is endowed with theoretically sound and practically significant meaning. The aim of the work is to preliminary determine the potential for creating a biologically active substance with antifungal action based on 1-alkyl derivatives of 3,5-dimethy-l-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide. Materials and methods. The toxicity of the studied compounds has been predicted using the TEST program (Toxicity Estimation Software Tool), which allowed to determine the predictive level of acute toxicity, ecotoxicity and mutagenicity. The physicochemical and pharmacokinetic parameters have been predicted, and the drug-like properties and availability of the investigated substances have been assessed using the online resource SwissADME. The determination of the most favorable spatial configuration of the ligand relative to the active site of the protein and the assessment of the strength of their interaction have been realized using the computational method of molecular docking. The ligands have been prepared using MarvinSketch 6.3.0, HyperChem 8 and AutoDock Tools-1.5.6 software. The preparation of the model enzyme has been based on the use of Discovery Studio 4.0 and AutoDock Tools-1.5.6. The practical implementation of flexible molecular docking has been carried out using the software tools of the AutoDock/Vina platform. Results. In the process of step-by-step prescreening of the formed structures of a number of 1-alkyl derivatives of 3,5-dimethyl-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide, a number of qualitative and quantitative indicators related to the physicochemical characteristics and pharmacokinetic parameters of the studied substances have been obtained. According to the results of the first stage of research, the group of substances under consideration can be predictively considered low-toxic, but with a high risk of mutagenic properties. The next stage of the work, which involved the analysis of physicochemical parameters, pharmacokinetic parameters, general drug-like properties and bioavailability, allowed us to identify 1-alkyl derivatives of 3,5-dimethyl-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide as substances with a rather positive pharmacological profile. The final stage in the form of molecular docking of the structure of the studied compounds to the active site of lanosterol 14α-demethylase allowed us to determine the nature of the chemical interaction and the type of amino acid residues that may be involved in the antifungal properties of the key ligands. The analysis of the docking results allows us to determine the privileged nature of the nonyl substituent at the first Nitrogen atom of the 1,2,4-triazole synthon in the structure of the presented series of compounds for the formation of antifungal properties. Conclusions. The general prospects for the creation of a biologically active substance with antifungal properties using 1-alkyl derivatives of 3,5-dimethyl-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide look quite realistic. Particular attention should be paid to 3,5-dimethyl-1-nonyl-4-((4-nitrobenzylidene)amino)-1,2,4-triazolium bromide as a substance with significant potential for antifungal properties, which allows us to recommend this compound for further more constructive and extended in vitro and in vivo studies.

Positional Isomerism: A Novel Paradigm for Enhancing Iodine Adsorption in Functionalized Metal-Organic Frameworks.

Porous metal-organic frameworks (MOFs) have shown great potential as adsorbents for capturing radioiodine, a major fission product generated during the reprocessing of nuclear fuel. However, studies exploring the correlation between the structure of MOFs and iodine uptake capacity remain notably rare. In this study, we introduce a new strategy for enhancing the iodine adsorption efficiency of MOFs by strategically varying the position of functional groups on the organic linkers. Employing ligand-functionalized UiO-67 MOFs, our findings reveal that ortho-amino substitution of UiO-67-o-NH2, proximal to the node of the dicarboxylate linker, markedly accelerates adsorption kinetics of iodine vapor in comparison to meta-amino substitution of UiO-67-m-NH2, where the amino groups are oriented away from the node. In contrast, UiO-67-m-NH2 exhibits a higher adsorption capacity of 2.19 g/g, compared to 1.91 g/g for UiO-67-o-NH2, attributable to its higher porosity. Furthermore, a competitive I2/H2O vapor adsorption study demonstrated that UiO-67-o-NH2 exhibits faster adsorption kinetics and higher selectivity for iodine in the presence of water vapor compared to UiO-67-m-NH2. Additionally, the crucial influence of positional isomerism on enhancing iodine adsorption has been corroborated through Raman spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. These analyses reveal that the nitrogen atom positioned at the ortho site demonstrates a stronger affinity for iodine molecules compared to the nitrogen atom at the meta site, thereby improving adsorption kinetics.

Synthesis and Characterization of Boron Nitride Thin Films Deposited by High-Power Impulse Reactive Magnetron Sputtering

In the present research, hexagonal boron nitride (h-BN) films were deposited by reactive high-power impulse magnetron sputtering (HiPIMS) of the pure boron target. Nitrogen was used as both a sputtering gas and a reactive gas. It was shown that, using only nitrogen gas, hexagonal-boron-phase thin films were synthesized successfully. The deposition temperature, time, and nitrogen gas flow effects were studied. It was found that an increase in deposition temperature resulted in hydrogen desorption, less intensive hydrogen-bond-related luminescence features in the Raman spectra of the films, and increased h-BN crystallite size. Increases in deposition time affect crystallites, which form larger conglomerates, with size decreases. The conglomerates’ size and surface roughness increase with increases in both time and temperature. An increase in the nitrogen flow was beneficial for a significant reduction in the carbon amount in the h-BN films and the appearance of the h-BN-related features in the lateral force microscopy images.

A Comprehensive Journey of a Vanillic Aldehyde-Chloroaniline Schiff Base from Solvent-Free Synthesis to Electronic Structure, In Silico and In Vitro Biological Analysis

Schiff bases possess a range of unique physical, chemical and medicinal properties, which contribute to their potency as biological agents. A Schiff base was synthesized, which consisted of 4-chloro aniline and vanillin. The successful formation of the compound was confirmed by their comparable FTIR, UV–Vis, 1HNMR and [Formula: see text]CNMR spectra. The compound was analyzed using X-ray crystallography, which revealed that it crystallizes in the monoclinic system with the space group P21/c. The Hirshfeld surface analysis revealed valuable information about the intermolecular interactions present in the crystal lattice. The most common contacts observed were between hydrogen and hydrogen, as well as carbon and hydrogen. The obtained fluorescence values of 375 nm and 412 nm at excitation wavelength 322 nm strongly indicated the luminescent nature of the compound. The thermal stability of the compound was assessed through thermogravimetric analysis (TGA). DFT was used to optimize the geometry using the B3LYP/cc-pVDZ basis set. The compound exhibited an energy gap of 2.35 electron volts (eV). According to the analysis of molecular electrostatic potential, C and O atoms were found to be electrophilic. According to Mulliken charge analysis, C atoms possess both positive and negative charges, hydrogen atoms exclusively carry positive charges, and Cl, O and N atoms exclusively carry negative charges. Upon analysis of the molecule, the electron localization function discovered that the atoms of carbon, nitrogen and chlorine exhibited delocalized electron density. Also, the localized orbital locator identified the localized orbital positions in the hydrogen atoms. The reduced density gradient (RDG) maps exhibit a wide range of noncovalent interactions. In comparison to the standard amoxicillin, the synthesized compound demonstrated moderate antimicrobial efficacy against the gram-positive bacteria Klebsiella pneumoniae and the fungi Candida albicans. The compound’s concentration-dependent antioxidant and anti-inflammatory properties were demonstrated through in vitro biological evaluation using 2,2-diphenyl-1-picrylhydrazyl and human red blood cell (HRBC) methods. The compound was docked using the proteins 7BYE and 4LEB were chosen from both organisms. The lowest binding attractions obtained were -3.40 kcal/mol for 7BYE and -4.51 kcal/mol for 4LEB. To investigate the stability of the protein–ligand complex, molecular dynamic simulation was employed. The ligands in silico toxicity potentialities were analyzed using seven toxicity models and the results indicated that the ligand is biocompatible.

Optimizing residue return with soil moisture and nutrient stoichiometry reduced greenhouse gas fluxes in Alfisols

Optimum soil moisture and high crop residue return (RR) can increase the active pool of soil organic carbon and nitrogen, thus modulating the magnitude of greenhouse gas (GHG) fluxes. To determine the effect of soil moisture on the threshold level of RR for the wheat production system, we analyzed the relationship between GHG fluxes and RR at four levels, namely 0, 5, 10, and 15 Mg ha−1 (R0, R5, R10, and R15) under two soil moisture content (80% FC and 100% FC) and three levels of nutrient management (NS0: no nutrient; NS1, NS2= 3x NS1). Nutrient input (N and P) in NS1 balanced the residue C/nutrient stoichiometry to achieve 30% stabilization of the residue C input in RR (R5). All RR treatments (cf. R0) were found to significantly reduce N2O emission in moderate soil moisture content (80% FC) by 22–56% across nutrient management due to enhanced soil C mineralization, microbial biomass carbon, and N immobilization. However, averaged across nutrient management, a linear increase in N2O emission was observed with increasing RR under 100% FC soil moisture. A significant decrease in CH4 emission by ca. 46% in most RR treatments was observed in 100% FC compared with the R0. The N2O emission was negatively correlated (p = &amp;lt;0.001) with nutrient stoichiometry. Partial least square (PLS) regression indicated that GHG emissions were more responsive (values &amp;gt; 0.8) to management variables (RR rate, nitrogen (N) input rate, soil moisture, and nutrient stoichiometry of C: N) and post-incubation soil properties (SMBC and NO3-N) in Alfisols. This study demonstrated that the mechanisms responsible for RR effects on soil N2O, CH4 fluxes, and carbon mineralization depend on soil moisture and nutrient management, shifting the nutrient stoichiometry of residue C: N: P.

Sewage-and fertilizer-derived nutrients alter the intensity, diversity, and toxicity of harmful cyanobacterial blooms in eutrophic lakes

Cyanobacterial harmful algal blooms (CHABs) are promoted by excessive nutrient loading and, while fertilizers and sewage are the most prevalent external nutrient sources in most watersheds, the differential effects of these nutrient sources on CHABs are unknown. Here, we tracked CHABs and performed experiments in five distinct lakes across the Northern US including Lake Erie. Fertilizers with ammonium and orthophosphate, membrane (0.2 μm)-filtered sewage (dominated by reduced forms of nitrogen) sand-and membrane-filtered sewage (dominated by nitrate), and an inorganic nutrient solution of ammonium and orthophosphate were used as experimental nutrient sources for CHABs at N-equivalent, environmentally realistic concentrations. Phytoplankton communities were evaluated fluorometrically, microscopically, and via high throughput sequencing of the 16S rRNA gene, and levels of microcystin and the δ15N content of particulate organic nitrogen (δPO15N) were quantified. Fertilizer and both sources of wastewater increased the abundance of cyanobacteria in all experiments across all five lakes (p &amp;lt; 0.05 for all) whereas effects on eukaryotic phytoplankton were limited. Sand-filtered sewage contained less P, organic matter, and ammonium but more nitrate and had a 25% less potent stimulatory effect on cyanobacteria than membrane-filtered sewage, suggesting nitrification may play a role in reducing CHABs. Fertilizer increased microcystin levels and decreased the δPO15N whereas wastewater increased δPO15N (p &amp;lt; 0.05 for all). Microcystis was the genus most consistently promoted by nutrient sources (p &amp;lt; 0.05 in all experiments), followed by Cyanobium (p &amp;lt; 0.05 in 50% of experiments), with increases in Microcystis biomass consistently elicited by membrane-filtered wastewater. Collectively, results demonstrate that differing types of sewage discharge and fertilizers can promote CHAB intensity and toxicity, while concurrently altering CHAB diversity and δPO15N. While membrane-filtered sewage consistently favored Microcystis, the discharge of sewage through sands muted bloom intensity suggesting sand-beds may represent a tool to remove key nutrients and partially mitigate CHABs.

Observational study of ground-level ozone and climatic factors in Craiova, Romania, based on one-year high-resolution data.

Air pollution is a multifaceted issue affecting people's health, environment, and biodiversity. Gaining comprehension of the interactions between natural and anthropocentric pollutant concentrations and local climate is challenging. This study aims to address the following two questions: (1) What is the influential mechanism of climatic and anthropogenic factors on the ground-level ozone (O3) concentrations in an urban environment during different seasons? (2) Can the ozone weekend effect be observed in a medium-sized city like Craiova, and under which conditions? In order to answer these questions, ozone interactions with meteorological parameters (temperature, pressure, relative humidity) and pollutant concentrations (particulate matter, carbon dioxide, volatile organic compounds, formaldehyde, nitrogen dioxide, nitric oxide and carbon monoxide) is evaluated based on a one-year dataset given by a low-cost sensor and one-year dataset provided by the National Environment Agency. Using two statistical analysis programs, Python and SPSS, a good understanding of the correlations between these variables and ozone concentration is obtained. The SPSS analysis underscores the significant impact of three meteorological factors and nine other pollutants on the ozone level. A positive correlation is noticed in the summer when sunlight is intense and photochemical reactions are elevated. The relationship between temperature and ozone concentration is strong and positive, as confirmed by Spearman's rho correlation coefficient (r = 0.880). A significant negative correlation is found between relative humidity and ozone (r = -0.590). Moreover, the analysis shows that particulate matter concentrations exhibit a significant negative correlation with ozone (r ≈ -0.542), indicating that higher particulate matter concentrations reduce ozone levels. Volatile organic compounds show a significant negative correlation with ozone (r = -0.156). A negative relationship between ozone and carbon dioxide (r = -0.343), indicates that elevated carbon dioxide levels might also suppress ozone concentrations. A significant positive correlation between nitrogen dioxide and ozone (r = 0.060), highlights the role of nitrogen dioxide in the production of ozone through photochemical reactions. However, nitric oxide shows a negative correlation with ozone (r = -0.055) due to its role in ozone formation. Carbon monoxide has no statistically significant effect on ozone concentration. To observe the differences between weekdays and weekends, T-Test was used. Even though significant differences were observed in temperature, humidity, carbon dioxide, volatile organic compounds, nitrogen dioxide, nitric oxide and carbon monoxide levels between weekdays and weekends, the T-Test did not highlight a significant weekend ozone effect in a mid-sized city as Craiova. Using Python, the daily values were calculated and compared with the limit values recommended by the World Health Organization (WHO) and European Environment Agency (EEA). The WHO O3 recommended levels were exceeded for 13 times in one year. This study offers a comprehensive understanding of ozone pollution in a mid-sized city as Craiova, serving as a valuable reference for local decision-makers. It provides critical insights into the seasonal dynamics of ozone levels, emphasizing the significant role of temperature in ozone formation and the complex interactions between various pollutants and meteorological factors.

Carbodicarbene‐Stibenium Ion‐Mediated Functionalization of C(sp3)−H and C(sp)−H Bonds

AbstractMain‐group element‐mediated C−H activation remains experimentally challenging and the development of clear concepts and design principles has been limited by the increased reactivity of relevant complexes, especially for the heavier elements. Herein, we report that the stibenium ion [(pyCDC)Sb][NTf2]3 (1) (pyCDC=bis‐pyridyl carbodicarbene; NTf2=bis(trifluoromethanesulfonyl)imide) reacts with acetonitrile in the presence of the base 2,6‐di‐tert‐butylpyridine to enable C(sp3)−H bond breaking to generate the stiba‐methylene nitrile complex [(pyCDC)Sb(CH2CN)][NTf2]2 (2). Kinetic analyses were performed to elucidate the rate dependence for all the substrates involved in the reaction. Computational studies suggest that C−H activation proceeds via a mechanism in which acetonitrile first coordinates to the Sb center through the nitrogen atom in a κ1 fashion, thereby weakening the C−H bond which can then be deprotonated by base in solution. Further, we show that 1 reacts with terminal alkynes in the presence of 2,6‐di‐tert‐butylpyridine to enable C(sp)−H bond breaking to form stiba‐alkynyl adducts of the type [(pyCDC)Sb(CCR)][NTf2]2 (3 a–f). Compound 1 shows excellent specificity for the activation of the terminal C(sp)−H bond even across alkynes with diverse functionality. The resulting stiba‐methylene nitrile and stiba‐alkynyl adducts react with elemental iodine (I2) to produce iodoacetonitrile and iodoalkynes, while regenerating an Sb trication.

Effect of Extracted Walnut Pomace Cake Edible Coating and Packaging Type on Quality Parameters of Walnut (Juglans regia L.) Kernels During Long Storage Periods

Walnuts are highly valued for their rich nutritional content, but their quality degrades during storage due to oxidation and other quality reducing processes. This study investigated the use of bioactive compounds extracted from walnut pomace, a by-product of walnut oil production, to develop an edible coating that extends the shelf life of ‘Milotai 10’ walnut kernels. Walnut kernels were stored for eight months in four different packaging materials (PE, PP, MPP, PLA) and three treatments were used (air or without treatment, nitrogen gas, and walnut pomace extract coating). The effects of these combinations on walnut quality parameters, including polyphenol content, vitamin E, fatty acids, peroxide value, and color, were analyzed. The results show that the combination of metallized polypropylene packaging under nitrogen treatment or with atmospheric air and walnut pomace extract (MPP-A-E+) best preserves walnut quality, making it a promising option for extending shelf-life.

Intrinsic Chemical Drivers of Organic Aerosol Volatility: From Experimental Insights to Model Predictions

AbstractAccurately predicting the volatilities of molecules in aerosols is challenging but crucial for understanding the atmospheric effects of aerosols. We used negative and positive ion electrospray ionization Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) to identify differences in the molecular compositions of gas and particle phase samples from urban atmosphere. We aimed to identify intrinsic chemical parameters that determine and predict the organic aerosol volatility. We found higher average molecular weights, carbon mass percentages, and double bond equivalents (DBE) but lower average O/C ratios and oxygen mass percentages in the particle phase than the gas phase. We identified DBE, which display a significant negative correlation with volatility, as a key parameter. We proposed to improve the previous model for predicting organic aerosol volatility by incorporating DBE as a new variant; and the result showed that this subsequently improved the accuracy of the model, particularly for compounds with minimal or no heteroatoms (0–2) such as hydrocarbons (CH). The revised model offers insights into the contributions of DBE, carbon, nitrogen, oxygen, and sulfur atoms to the volatilities of diverse organic molecules in aerosols and could be applied to improve our understanding of the phase distributions of volatile organic compounds in the ambient air.

Synthesis, Spectroscopy and Biological Studies of Copper and Silver Complexes Derived from 2-Substituted Amino Propanoic Acid

Synthesis of copper and silver complexes were prepared from novel Schiff base ligand. These synthesized ligand and their metal complexes were characterized by elemental analysis, FT-IR, 1H NMR, UV-Vis and Mass spectrometry. The coordination of amino nitrogen, phenolic oxygen, and carboxylato oxygen atoms is shown by the infrared spectra.The Schiff bases and its complexes were screened for their in vitro antibacterial and antifungal studies against the bacteria Pseudomonas Aeruginosa (PA, Gram -ve), Bacillus Cirroflagellosus (BC, Gram +ve), Penicillium Notatium (PN) and Aspergillus Niger (AN) strains. The results of the antibacterial investigation show that the copper and silver complexes possess more potent bactericide and fungicide properties than the ligand.