Saturated Molecules Research Articles

High-Resolution Mass Spectrometry Combined with Reactive Oxygen Species Reveals Differences in Photoreactivity of Dissolved Organic Matter from Microplastic Sources in Aqueous Environments.

Microplastics (MPs)-derived dissolved organic matter (MPs-DOM) is becoming a non-negligible source of DOM pools in aquatic systems, but there is limited understanding about the photoreactivity of different MPs-DOM. Herein, MPs-DOM from polystyrene (PS), polyethylene terephthalate (PET), poly(butylene adipate-co-terephthalate) (PBAT), PE, and polypropylene (PP), representing aromatic, biodegradable, and aliphatic plastics, were prepared to examine their photoreactivity. Spectral and high-resolution mass spectrometry analyses revealed that PS/PET/PBAT-DOM contained more unsaturated aromatic components, whereas PE/PP-DOM was richer in saturated aliphatic components. Photodegradation experiments observed that unsaturated aromatic molecules were prone to be degraded compared to saturated aliphatic molecules, leading to a higher degradation of PS/PET/PBAT-DOM than PE/PP-DOM. PS/PET/PBAT-DOM was mainly degraded by hydroxyl (•OH) via attacking unsaturated aromatic structures, whereas PE/PP-DOM by singlet oxygen (1O2) through oxidizing aliphatic side chains. The [•OH]ss was 1.21-1.60 × 10-4 M in PS/PET/PBAT-DOM and 0.97-1.14 × 10-4 M in PE/PP-DOM, while the [1O2]ss was 0.90-1.35 × 10-12 and 0.33-0.44 × 10-12 M, respectively. This contributes to the stronger photoreactivity of PS/PET/PBAT-DOM with a higher unsaturated aromatic degree than PE/PP-DOM. The photodegradation of MPs-DOM reflected a decreasing tendency from aromatic-unsaturated molecules to aliphatic-saturated molecules. Special attention should be paid to the photoreactivity and environmental impacts associated with MPs-DOM containing highly unsaturated aromatic compounds.

Late-Stage Saturation of Drug Molecules.

The available methods of chemical synthesis have arguably contributed to the prevalence of aromatic rings, such as benzene, toluene, xylene, or pyridine, in modern pharmaceuticals. Many such sp2-carbon-rich fragments are now easy to synthesize using high-quality cross-coupling reactions that click together an ever-expanding menu of commercially available building blocks, but the products are flat and lipophilic, decreasing their odds of becoming marketed drugs. Converting flat aromatic molecules into saturated analogues with a higher fraction of sp3 carbons could improve their medicinal properties and facilitate the invention of safe, efficacious, metabolically stable, and soluble medicines. In this study, we show that aromatic and heteroaromatic drugs can be readily saturated under exceptionally mild rhodium-catalyzed hydrogenation, acid-mediated reduction, or photocatalyzed-hydrogenation conditions, converting sp2 carbon atoms into sp3 carbon atoms and leading to saturated molecules with improved medicinal properties. These methods are productive in diverse pockets of chemical space, producing complex saturated pharmaceuticals bearing a variety of functional groups and three-dimensional architectures. The rhodium-catalyzed method tolerates traces of dimethyl sulfoxide (DMSO) or water, meaning that pharmaceutical compound collections, which are typically stored in wet DMSO, can finally be reformatted for use as substrates for chemical synthesis. This latter application is demonstrated through the late-stage saturation (LSS) of 768 complex and densely functionalized small-molecule drugs.

An investigation into the impact of CuAl2O4 hydrophobization on catalyst structure and performance for syngas conversion

The intricate structure and surface properties of metal oxide catalysts pose a challenge for implementing hydrophobic surface treatment. Herein, the surface of CuAl2O4 catalysts is modified by means of grafting and bridging different saturated fatty acid molecules, including lauric acid, palmitic acid and stearic acid. Consequently, the modification leads to an enhancement in the hydrophobicity of the catalyst, as evidenced by an increase in the static water contact angle from 15.26° to 150.74°. The hydrophobization of CuAl2O4 catalysts, in turn, influences the decomposition and reduction capacity of CuAl2O4, thus favoring the formation of a more stable defective spinel structure and improving the dispersion of Cu particles, thereby restraining aggregation. Notably, the activity results indicate that the hydrophobically modified CuAl2O4 exhibits higher CO conversion and selectivity of dimethyl ether, while effectively suppressing the water–gas shift reaction and reducing CO2 selectivity. This observation points to the significance of the catalyst surface hydrophobicity in enhancing catalytic performance.

Enrichment and movability of lacustrine tight shale oil for the first member of the Upper Cretaceous Qingshankou Formation in the Sanzhao Sag, Songliao Basin, NE China: Insights from saturated hydrocarbon molecules

The Sanzhao Sag is one of the main hydrocarbon generation sags with good shale oil exploration and exploitation potential in the northern Songliao Basin, and the first member of the Upper Cretaceous Qingshankou Formation (K2qn1) is regarded as the most important target layer. In this paper, the complete K2qn1 rock cores from the first shale oil parameter well named the SYY3 well in the study area were taken to investigate tight shale oil enrichment and movability from saturated hydrocarbon molecules combined with bulk organic geochemical characteristics. The results show that the K2qn1 mudstones/shales in the SYY3 well are of high organic matter abundance (1.28–5.62 wt% TOC), good organic matter types (I and II1 kerogens) and medium maturity (0.82%–0.98% Ro), creating excellent material basis of hydrocarbon generation for shale oil enrichment. The molecular compositions of saturated hydrocarbons suggest that the K2qn1 were deposited in reducing brackish lacustrine water with mainly prokaryotes and secondly eukaryotic algae as the biotic input, and are characterized by obvious two-stage distribution with buried depth. The lower unit (>2015.00 m) is generally more enriched in shale oil than the upper unit (<2015.00 m). Relative to the upper unit, the lower unit has lower ratios of pristane/phytane, gammacerane/C30 hopane, C19-20/C21-26 tricyclic terpanes, C24 tetracyclic terpane/C26 tricyclic terpanes, 4-methylstane/C27-29 αααR steranes, higher ratios of regular steranes/17α-hopanes, C27/C29 and C28/C29 αααR sterane, and higher contents of diadrimanes, diahopanes and diasteranes. This indicates that the lower unit can be deposited in a more reducing, lower salinity and more clay-rich sedimentary environment, and contains more eukaryotic algae and less prokaryote biotic input than the upper unit, which can be conducive to the formation and retention of shale oil in the lower unit. The S1 values showing certain positive correlations with regular steranes/17α-hopanes and C27/C29 αααR sterane indicates that the biotic input contribution of eukaryotic algae can be an important positive factor influencing free oil content. The negative correlation between (nC21 + nC22)/(nC28 + nC29) and OSI (S1 × 100/TOC) can be due to diffusion fractionation effect of hydrocarbon molecules in micro-nano reservoir spaces. Low (nC21 + nC22)/(nC28 + nC29) values usually indicate good shale oil movability and reservoir space connectivity under the similar thermal maturity.

Variations in redox properties of biochar and humic acid induced by interactive molecular exchange

Biochar and humic substances are prevalent redox pools in the environment, which is critical to electron transfer in geochemical cycles and pollution control processes. The dissolution of biochar and the sorption of humic substances on biochar have the potential to redistribute redox substances, consequently altering the redox properties of solid and liquid phases. However, studies have often focused on either sorption or dissolution separately, overlooking the mutual effects and not involving redox properties. Herein, molecular interactions between biochar and humic acid (HA) and variations in their redox properties were elucidated using UPLC Orbitrap MS and mediated electrochemical measurement. The dissolution of biochar was far greater than the sorption of HA constituents, and HA enhanced the dissolution of biochar through molecular exchange. But preferential sorption of oxygenated aromatics to pine char (pi500) mainly by hydrogen bonding and higher saturated molecules to starch char (st700) mainly by hydrophobic interactions caused the oxygenated functional groups on biochar to increase (1 ~ 1.5 times). Thus the Electron exchange capacities (EEC) of pi500 and st700 turned to 1 ~ 3 times, and the EEC of HA decreased ca. 50%. Absorption (partition) caused more sorption of HA constituents to pi500 than to st700, while larger surface area resulted in higher EEC of st700 with sorbed HA. The enrichment of redox constituents on biochar is promising for its long-term use in waste reclamation and pollution control. The findings can aid in the understanding of variations in redox properties under interactions between pyrolytic and natural organic matter.Graphical

Chemical differences among collapsing low-mass protostellar cores

Context. Organic features lead to two distinct types of Class 0/I low-mass protostars: hot corino sources exhibiting abundant saturated complex organic molecules (COMs) and warm carbon-chain chemistry (WCCC) sources exhibiting abundant unsaturated carbon-chain molecules. Some observations suggest that the chemical variations between WCCC sources and hot corino sources are associated with local environments and the luminosity of protostars. Aims. We aim to investigate the physical conditions that significantly affect WCCC and hot corino chemistry, as well as to reproduce the chemical characteristics of prototypical WCCC sources and hybrid sources, where both carbon-chain molecules and COMs are abundant. Methods. We conducted a gas-grain chemical simulation in collapsing protostellar cores, adopting a selection of typical physical parameters for the fiducial model. By adjusting the values of certain physical parameters, such as the visual extinction of ambient clouds (AVamb), cosmic-ray ionization rate (ζ), maximum temperature during the warm-up phase (Tmax), and contraction timescale of protostars (tcont), we studied the dependence of WCCC and hot corino chemistry on these physical parameters. Subsequently, we ran a model with different physical parameters to reproduce scarce COMs in prototypical WCCC sources. Results. The fiducial model predicts abundant carbon-chain molecules and COMs. It also reproduces WCCC and hot corino chemistry in the hybrid source L483. This suggests that WCCC and hot corino chemistry can coexist in some hybrid sources. Ultraviolet (UV) photons and cosmic rays can boost WCCC features by accelerating the dissociation of CO and CH4 molecules. On the other hand, UV photons can weaken the hot corino chemistry by photodissociation reactions, while the dependence of hot corino chemistry on cosmic rays is relatively complex. The value of Tmax does not affect any WCCC features, while it can influence hot corino chemistry by changing the effective duration of two-body surface reactions for most COMs. The long tcont can boost WCCC and hot corino chemistry by prolonging the effective duration of WCCC reactions in the gas phase and surface formation reactions for COMs, respectively. The scarcity of COMs in prototypical WCCC sources can be explained by insufficient dust temperatures in the inner envelopes that are typically required to activate hot corino chemistry. Meanwhile, the high ζ and the long tcont favors the explanation for scarce COMs in these sources. Conclusions. The chemical differences between WCCC sources and hot corino sources can be attributed to the variations in local environments, such as AVamb and ζ, as well as the protostellar property, tcont.

ATR-far-ultraviolet spectroscopy: a challenge to new σ chemistry.

This review reports the recent progress on ATR-far ultraviolet (FUV) spectroscopy in the condensed phase. ATR-FUV spectroscopy for liquids and solids enables one to explore various topics in physical chemistry, analytical chemistry, nanoscience and technology, materials science, electrochemistry, and organic chemistry. In this review, we put particular emphasis on the three major topics: (1) studies on electronic transitions and structures of various molecules, which one cannot investigate via ordinary UV spectroscopy. The combined use of ATR-FUV spectroscopy and quantum chemical calculations allows for the investigation of various electronic transitions, including σ, n-Rydberg transitions. ATR-FUV spectroscopy may open a new avenue for σ-chemistry. (2) ATR-FUV spectroscopy enables one to measure the first electronic transition of water at approximately 160 nm without peak saturation. Using this band, one can study the electronic structure of water, aqueous solutions, and adsorbed water. (3) ATR-FUV spectroscopy has its own advantages of the ATR method as a surface analysis method. ATR-FUV spectroscopy is a powerful technique for exploring a variety of top surface phenomena (∼50 nm) in adsorbed water, polymers, graphene, organic materials, ionic liquids, and so on. This review briefly describes the principles, characteristics, and instrumentation of ATR-FUV spectroscopy. Next, a detailed description about quantum chemical calculation methods for FUV and UV regions is given. The recent application of ATR-FUV-UV spectroscopy studies on electronic transitions from σ orbitals in various saturated molecules is introduced first, followed by a discussion on the applications of ATR-FUV spectroscopy to studies on water, aqueous solutions, and adsorbed water. Applications of ATR-FUV spectroscopy in the analysis of other materials such as polymers, ionic liquids, inorganic semiconductors, graphene, and carbon nanocomposites are elucidated. In addition, ATR-FUV-UV-vis spectroscopy focusing on electrochemical interfaces is outlined. Finally, FUV-UV-surface plasmon resonance studies are discussed.

Impact of diamond nanothread on the viscosity of asphalt binder: Insights from atomistic simulations

Viscosity stands as a pivotal property within asphalt binder, exerting influence not only over the pavement quality and construction efficiency but also over energy consumption and harmful gas emissions. Lower viscosity at the mixing temperature can reduce the energy consumption and emissions remarkably. As such, extensive efforts have been devoted to tailor the viscosity of asphalt by adding nanomaterials. Through atomistic simulations, this work provides an in-depth assessment on the viscosity of asphalt binder modified by ultrathin diamond nanothread (DNT). It is observed that the addition of DNT can reduce the viscosity of asphalt, a phenomenon traced back to the sp3-bonded nature of DNT that prevents the formation of π - π bonds with asphaltene molecules. Notably, samples endowed with higher count of stacked asphaltene molecules tend to display higher viscosity. Further investigation reveals that the sample with aggregated DNTs exhibits a lower viscosity, as the aggregated DNTs exert a more subdued influence on asphalt molecule mobility. Specifically, DNTs are found to promote the mobility of all molecules, and a remarkable enhancement on the mobility of saturated molecules is observed. This distinct behavior sets them apart from single-walled carbon nanotubes (SWNTs), where viscosity rises with increasing content due to the SWNT-induced aggregation of asphaltene molecules. Overall, this work unveils the intricate mechanisms influencing the viscosity of asphalt binders through diamond nanostructures. These findings could be beneficial for the design of asphalt binders with tailored rheological properties.

Mechanism analysis of Lignin's effect on Asphalt's resistance to moisture damage

The present study investigates the mechanism by which lignin enhances the moisture resistance of asphalt materials, employing a combination of atomic force microscopy (AFM) and molecular simulations. The research aims to understand the changes in surface morphology and adhesion properties of asphalt upon immersion, and elucidate the role of lignin modification in mitigating the reduction of adhesive forces. AFM measurements reveal that lignin-modified asphalt exhibits higher adhesion force after moisture damage, possibly attributable to less nanostructures on the surface of lignin modified asphalt. Molecular dynamics simulations are employed to study the binding energies between lignin and different asphalt constituents. The results demonstrate that lignin exhibits the strongest binding affinity with asphaltene molecules, and also displays significant binding affinity with a specific saturated molecule. Furthermore, diffusion of water molecules on asphalt surfaces is investigated, revealing that lignin-modified asphalt exhibits lower water molecule diffusion coefficients and reduced binding energies. Finally, a spherical water molecule model is employed to analyze the wetting behavior on lignin-modified asphalt surfaces, illustrating the dual mechanism of lignin molecules resisting water molecules and inhibiting the binding of polar molecules within asphalt to water molecules. The findings of this research provide insights into the enhancement of moisture resistance in asphalt materials through lignin modification. The combination of AFM and molecular simulations offers a comprehensive understanding of the morphological and adhesive changes at the nanoscale, as well as the fundamental molecular interactions involved. The results contribute to the development of strategies for designing and engineering asphalt materials with improved resistance to moisture damage.

Cathodic Electrolysis: Electroreductive Organic Synthesis

AbstractCathodic reductive electrolysis in organic transformations is used to generate radical anions. These electrochemical reduction reactions are very useful in various carbonyl groups transformation (such as aldehydes, ketones, esters, and amides), new bond formations as well as reduction of saturated and unsaturated molecules. Reductive electrocarboxylation reactions to access various valuable chemicals are one of the important applications of cathodic reductive electrolysis. Herein, we review particularly the electrochemical organic transformation reactions taking place at the cathode. We also discuss how alternative strategies such as paired electrolysis, photo‐electrolysis, and alternating current electrolysis can be used to overcome the limitations associated with cathodic electrolysis and how they will improve sustainable electrochemical transformations.

Laboratory Measurement of CH2DOH Line Intensities in the Millimeter-wave Region

Deuterium fractionation in molecules is known as one of the most powerful tools to study chemical processes during star and planet formation. Among various interstellar molecules, methanol often shows very high deuterium fractionation. It is the most abundant saturated organic molecule and is known as a parent species to form more complex organic molecules. However, deriving the abundance of deuterated methanol suffers from the uncertainty in the intrinsic line intensities (S μ 2) of CH3OH isotopologues. Due to their floppy nature, theoretical evaluation of the S μ 2 values is not straightforward, particularly for asymmetric-top asymmetric-frame isotopologues such as CH2DOH. In this study, we have measured the line frequencies and their intensities for CH2DOH in the millimeter-wave region from 216 to 264 GHz by using an emission-type millimeter and submillimeter-wave spectrometer. For the a-type J = 5 − 4 transition, the derived S μ 2 values are 13%–27% larger than those theoretically calculated, except for the transitions of K a = 2 for e 0 and K a = 1 for e 1 affected by avoided level crossing. For b-type transitions, significant systematic differences are found between theoretical and experimental S μ 2 values. The results of the present study enable us to accurately derive from observations the CH2DOH abundances, which are essential for understanding deuterium fractionation in various sources.

Kinetic control of liposome size by direct lipid transfer

Spontaneous lipid vesiculation and related size distribution are traditionally studied in the framework of equilibrium thermodynamics and continuum mechanics, overlooking the kinetic aspects of the process. In the scenario of liposomes consisting of different lipid molecules dispersed in the same medium - a non-equilibrium situation -, the system evolves driven by lipid monomer transfer among the different liposomes. This process encompasses time-dependent changes in liposome size and size distribution, thus predicting size and composition at a given time would entail the control of the size of liposomes by kinetic means, an asset in the framework of diagnostics and synthetic biology. We introduce a direct transfer model, based on the fact that monomers are highly reactive species and apply it to saturated phospholipid molecules differing in hydrophobic chain length. Considering a well-defined gamma-type liposome size distribution, we demonstrate a clear liposome size-composition correlation and are able to predict liposome size and size distribution at any time in the transfer process. The size-composition correlation opens up new prospects for the control of the self-assembling properties of lipids and thereby the control of the liposome size.

Chemical Differentiation around Five Massive Protostars Revealed by ALMA: Carbon-chain Species and Oxygen/Nitrogen-bearing Complex Organic Molecules

We present Atacama Large Millimeter/submillimeter Array Band 3 data toward five massive young stellar objects (MYSOs), and investigate relationships between unsaturated carbon-chain species and saturated complex organic molecules (COMs). An HC5N (J = 35–34) line has been detected from three MYSOs, where nitrogen (N)-bearing COMs (CH2CHCN and CH3CH2CN) have been detected. The HC5N spatial distributions show compact features and match with a methanol (CH3OH) line with an upper-state energy around 300 K, which should trace hot cores. The hot regions are more extended around the MYSOs where N-bearing COMs and HC5N have been detected compared to two MYSOs without these molecular lines, while there are no clear differences in the bolometric luminosity and temperature. We run chemical simulations of hot-core models with a warm-up stage, and compare with the observational results. The observed abundances of HC5N and COMs show good agreements with the model at the hot-core stage with temperatures above 160 K. These results indicate that carbon-chain chemistry around the MYSOs cannot be reproduced by warm carbon-chain chemistry, and a new type of carbon-chain chemistry occurs in hot regions around MYSOs.

Nutritional Value of Wild and Domesticated Sanguisorba minor Scop. Plant

Sanguisorba minor Scop. is a wild edible species distributed in the Mediterranean area and present in numerous traditional food recipes. In the present study, the assessment of nutritional value (ash, carbohydrates, fat, proteins, energy, free sugars, organic acids, tocopherols, fatty acid composition, and minerals) of wild and domesticated S. minor plants was performed. Results showed an increase in ash, protein, fat, organic acid, and α-tocopherol content after the plant’s domestication. Retention of free sugars, especially sucrose, was observed from wild plants to domesticated ones. However, the cultivated plants reported a higher content of polyunsaturated fatty acids than saturated molecules, and both wild collection and domestication maintained a low ω6/ω3 ratio, confirming the role of this species in the prevention of oxidative and inflammatory processes. This aspect is also suggested by the high α-tocopherol content, a vitamin known for its ability to scavenge free-radical species. Nevertheless, a high oxalic acid content was found in domesticated plants. However, the management of fertilization in open field cultivation can be robust in terms of organic acid and mineral (e.g., calcium) content. Indeed, the most representative macrominerals found in domesticated plants were Ca and Mg. The present study suggests a possible introduction of S. minor species in the human diet as a functional food or ingredient by virtue of its high nutritional properties and contents. Moreover, the management of fertilization and domestication might be a solution to maintain/enhance the nutritional profile of this wild species.

Molecule Saturation Boosts Acetylene Semihydrogenation Activity and Selectivity on a Core‐Shell Ruthenium@Palladium Catalyst

AbstractIncreasing selectivity without the expense of activity is desired but challenging in heterogeneous catalysis. By revealing the molecule saturation and adsorption sensitivity on overlayer thickness, strain, and coordination of Pd‐based catalysts from first‐principles calculations, we designed a stable Pd monolayer (ML) catalyst on a Ru terrace to boost both activity and selectivity of acetylene semihydrogenation. The least saturated molecule is most sensitive to the change in catalyst electronic and geometric properties. By simultaneously compressing the Pd ML and exposing the high coordination sites, the adsorption of more saturated ethylene is considerably weakened to facilitate the desorption for high selectivity. The even stronger weakening to the least saturated acetylene drives its hydrogenation such that it is more exothermic, thereby boosting the activity. Tailoring the molecule saturation and its sensitivity to structure and composition provides a tool for rational design of efficient catalysts.

Molecule Saturation Boosts Acetylene Semihydrogenation Activity and Selectivity on a Core-Shell Ruthenium@Palladium Catalyst.

Increasing selectivity without the expense of activity is desired but challenging in heterogeneous catalysis. By revealing the molecule saturation and adsorption sensitivity on overlayer thickness, strain, and coordination of Pd-based catalysts from first-principles calculations, we designed a stable Pd monolayer (ML) catalyst on a Ru terrace to boost both activity and selectivity of acetylene semihydrogenation. The least saturated molecule is most sensitive to the change in catalyst electronic and geometric properties. By simultaneously compressing the Pd ML and exposing the high coordination sites, the adsorption of more saturated ethylene is considerably weakened to facilitate the desorption for high selectivity. The even stronger weakening to the least saturated acetylene drives its hydrogenation such that it is more exothermic, thereby boosting the activity. Tailoring the molecule saturation and its sensitivity to structure and composition provides a tool for rational design of efficient catalysts.

Rate constants for the reactions of chloride monoxide radical (ClO•) and organic molecules of environmental interest.

ClO• plays a key role in the UV/chlorine process besides Cl•, Cl2• - , and •OH. In many experiments, ClO• proved to be the main reactant that destroyed the organic pollutants in advanced oxidation process. About 200 rate constants of ClO• reactions were collected from the literature, grouped together according to the chemical structure, and the molecular structure dependencies were evaluated. In most experiments, ClO• was produced by the photolytic reaction of HClO/ClO-. For a few compounds, the rate constants were determined by the absolute method, pulse radiolysis. Most values were obtained in steady-state experiments by competitive technique or by complex kinetic calculations after measuring the pollutant degradation in the UV/chlorine process. About 30% of the listed rate constant values were derived in quantum chemical or in structure-reactivity (QSAR) calculations. The values show at least six orders of magnitude variations with the molecular structure. Molecules having electron-rich parts, e.g., phenol/phenolate, amine, or sulfite group have high rate constants in the range of 108-109 mol-1 dm3 s-1. ClO• is inactive in reactions with saturated molecules, alcohols, or simple aromatic molecules.

Effect of electrolysis of gaseous water molecules with different voltages and frequencies of corona on the performance and emissions characteristics of the gasoline engine

Among various air pollution issues, exhaust emissions from internal combustion engines have become one of society’s primary concerns. This study analyzed the water system and plasma system installed on the intake manifold to investigate the effects of additional substances produced by the electrolysis of saturated gaseous water molecules on engine performance and exhaust emissions. The results indicate that electrolyzing gaseous water molecules produce hydrogen and oxygen at different voltages and frequencies of the corona, which affects the power efficiency and the brake-specific fuel consumption (BSFC) of internal combustion engines. Moreover, it affects the concentration of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). The result shows that engine power increased by 2.5%, BSFC decreased by 3%, and CO decreased by 9%. However, the result indicates that HC increased by 29%, and NOx increased by 21%. In conclusion, electrolyzing saturated gaseous water molecules in a non-thermal plasma improves engine performance but increases the concentration of HC and NOx. However, the changes in performance and exhaust emissions are only noticeable at higher ignition frequencies of the non-thermal plasma, and the performance changes at lower frequencies are like only using the water system.

Visualizing and comparing quantum interference in the π-system and σ-system of organic molecules.

Quantum interference effects in conjugated molecules have been well-explored, with benzene frequently invoked as a pedagogical example. These interference effects have been understood through a quantum interference map in which the electronic transmission is separated into interfering and non-interfering terms, with a focus on the π-orbitals for conjugated molecules. Recently, saturated molecules have also been reported to exhibit destructive quantum interference effects; however, the very different σ-orbital character in these molecules means that it is not clear how orbital contributions manifest. Herein, we demonstrate that the quantum interference effects in conjugated molecules are quite different from those observed in saturated molecules, as demonstrated by the quantum interference map. While destructive interference at the Fermi energy in the π-system of benzene arises from interference terms between paired occupied and virtual orbitals, this is not the case at the Fermi energy in saturated systems. Instead, destructive interference is evident when contributions from a larger number of non-paired orbitals cancel, leading to more subtle and varied manifestations of destructive interference in saturated systems.

Ligand‐Controlled Nickel‐Catalyzed Regiodivergent Cross‐Electrophile Alkyl‐Alkyl Couplings of Alkyl Halides

AbstractFunctionalizing specific positions on a saturated alkyl molecule is a key challenge in synthetic chemistry. Herein, a ligand‐controlled regiodivergent alkylations of alkyl bromides at different positions by Ni‐catalyzed alkyl‐alkyl cross‐electrophile coupling with the second alkyl bromides has been developed. The reaction undergoes site‐selective isomerization on one alkyl bromides in a controlled manner, providing switchable access to diverse alkylated structures at different sites of alkyl bromides. The reaction occurs at three similar positions with excellent chemo‐ and regioselectivity, representing a remarkable ligand tuned reactivity between alkyl‐alkyl cross‐coupling and nickel migration along the hydrocarbon side chain. This reaction offers a catalytic platform to diverse saturated architectures by alkyl‐alkyl bond‐formation from identical starting materials.