Carbon Research Articles

Assessment of Edge Modification of Nanographene.

Carboxy groups on the edges of nanographene (NG) enable functionalization for realizing NG-organic hybrid materials. Therefore, assessment of the edge-functionalization of the electronic structures of NGs is valuable for the rational design of functional carbon materials. In this study, the structures of model NGs comprising 174 carbon atoms with armchair edges and various functional groups at the edges were computed. To achieve the greatest possible similarity between the computed structure and the real one, the carbon framework was designed based on experimental observations. The functional groups can be accessed via suitable chemical reactions. The computations predicted that although the conversion of carboxyl groups with electron-withdrawing/donating groups influences the orbital energies, the HOMO-LUMO (H-L) gap is not significantly affected, except in a few cases. Among the evaluated examples, π-extension had the greatest influence on the H-L gap. Interestingly, for the Pd2+-coordinated NG, the participation of the low-lying LUMO localized on Pd2+ in the surface-to-metal transitions seemingly narrowed the H-L gap, and a surface-to-ligand transition was observed.

Radical Isomerization Homopolymerization of Linear α‐Olefins to Access C5, C6 or C7 Polymers

AbstractNon‐activated linear α‐olefins are valuable building blocks for organic transformation or olefin (co)polymerization, but they are recognized as textbook knowledge for non‐homopolymerizable monomers under radical conditions. In this article, we disclose our effort to achieve an unprecedented library of all carbon‐bonded sequence‐regulated polymers via radical isomerization homopolymerization of α‐olefin derivatives. The success of this distinctive polymerization is attributed to the remarkable efficiency and selectivity exhibited during the cyano group migration or hydrogen atom transfer, which is greatly enhanced by the precise engineering of their monomer structures. This polymerization process enables the elongation of polymer chains by five, six, or seven carbon atoms at each propagation step. These polymers, obtained through the cyano group migration or hydrogen atom transfer involved radical isomerization polymerization processes, emerge as promising candidates resembling polyethylene or polyacrylonitrile copolymers.

Benzoxaborinine, New Chemotype for Carbonic Anhydrase Inhibition: Ex Novo Synthesis, Crystallography, In Silico Studies, and Anti-Melanoma Cell Line Activity.

The benzoxaborinine scaffold, a homologue of benzoxaborole with an additional carbon atom in the boracycle, shows significant potential in developing new therapeutic agents. This study reports the synthesis, inhibition assays against four human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, and anti-melanoma evaluation of 7-aryl(thio)ureido-substituted benzoxaborinines. Some derivatives, particularly compound 11, exhibited potent inhibitory activity (below 65 nM) against hCA IX and XII and stronger antiproliferative effects than SLC-0111 on human melanoma cells under hypoxia. Crystallographic studies of benzoxaborinine 3 adducts with hCA I and II demonstrated the binding mode of this chemotype, revealing that although both benzoxaborinine 3 and benzoxaborole 10 share a similar zinc-binding mode, the expanded ring in benzoxaborinine led to a different orientation within the active site. These findings suggest that benzoxaborinines hold promise for designing novel carbonic anhydrase inhibitors.

Adsorption Property and Morphology Evolution of C Deposited on HCP Co Nanoparticles

Despite extensive studies of deposited carbon in Fischer–Tropsch synthesis (FTS), an atomic-level comprehension of the effect of carbon on the morphology of cobalt-based FTS catalysts remains elusive. The adsorption configurations of carbon atoms on different crystal facets of hexagonal close-packed (hcp) Co nanoparticles were studied using density functional theory (DFT) calculations to explore the interaction mechanism between C and Co surfaces. The weaker adsorption strength of C atoms on Co(0001), Co(10-10), and Co(11-20) surfaces accounted for lower diffusion energy, leading to the facile formation of C dimers. Electronic property analysis shows that more electrons are transferred from Co surfaces to C atoms on corrugated facets than on flat facets. The deposition of carbon atoms on Co nanoparticles affects surface energy by forming strong Co-C bonds, which causes the system to reach a more energetically favorable morphology with an increased proportion of exposed Co(10-12) and Co(11-20) areas as the carbon content increases slightly. This transformation in morphology implies that C deposition plays a crucial role in determining the facet proportion and stability of exposed Co surfaces, contributing to the optimization of cobalt-based catalysts with improved performance.

Spectrochemical Insights into Aromatic Hydrocarbons in 1,2-Disubstituted Naphthalenes: Investigations Using 1D and 2D NMR Spectroscopy and X-Ray Crystallography Analysis

Naphthalene and its derivatives are often determined as markers of environmental pollution, although they are also recognized as crucial building blocks in many beneficial compounds. In the course of this study, a range of 1,2-disubstituted naphthalenes bearing nitro, amine, sulfonate, chlorine, and hydroxyl substituents were synthesized and characterized using several spectroscopic techniques, including FT-IR,1H NMR,13C NMR, DEPT-90, DEPT-135, DEPTq, elemental analysis, and high-resolution mass (HRMs). The NMR analysis of the aromatic hydrocarbon moiety in these compounds emphasized the impact of substituent variations on the appearance of 1H and 13C NMR signals. To resolve the issue of overlapping one-dimensional (1D) 1H NMR signals and determine the connectivity of hydrogen and carbon atoms from the aromatic naphtayl ring, we employed a “two-dimensional” experiment, using homonuclear correlation spectroscopy (2D 1H-1H COSY) and heteronuclear single quantum correlation (2D 1H - 13C HSQC) and heteronuclear multiple‐bond correlation spectroscopy (2D 1H - 13C HMBC). This work also investigated the correlation between 1H NMR signals and thin-layer chromatography (TLC) data. X-ray crystallography data validates that the presence of a specific group, not aligned coplanarly with the naphthyl ring, exerts a spatial influence on the manifestation of 1H NMR signals, alongside other electronic effects. This study will offer NMR data, providing insights into the potential applications and analyses of naphthalene derivatives across various theoretical and practical domains.

Chemical characteristics of Salix psammophila sand barriers are accelerated degradation by ultraviolet irradiation and water

The implementation of Salix psammophila sand barriers measures constitutes a crucial element in desertification control, providing a solid theoretical foundation for the future application and pretreatment of sand barriers in production practices. To address the specific damage types predominant in desert environments, we executed simulations of ultraviolet irradiation and rainfall phenomena on mechanical sand barriers in sandy areas and also inspected the variations in chemical properties during accelerated aging processes. The findings unequivocally demonstrate that: (1) The synergistic impact of ultraviolet irradiation and water accelerated the deformation and fracturing of the S.psammophila sand barriers, thereby causing a partial degradation of its chemical properties and conspicuous lignin oxidation; (2) The fissure of the sand barrier deepened, resulting in structural alterations. The existence of water expedites the degradation process of S.psammophila sand barriers under ultraviolet irradiation. (3)With respect to the binding form of C atoms, the carbon atoms at S.psammophila sand barriers were highly oxidized after 576 hours of accelerated aging. The components of C2 (C-O) and C3 (C=O) rising to 40.16% and 12.24% respectively, while the components of C1 (C-C) declined to 47.60%. The amount of hydroxyl (O-C-O), carbonyl (C=O), and carboxyl (O-C=O) groups increases in line with the expansion of the contact area between the sand barrier structure and ultraviolet irradiation as well as water. More free radical substances are generated, thereby causing the chemical binding properties to tend to be more stable. In summary, Ultraviolet irradiation and water change are the primary factors influencing the degradation of S.psammophila sand barriers material structure and properties. In future desertification control, it is imperative to focus on enhancing the longevity of sand barriers by ensuring their waterproofing capabilities and resistance to ultraviolet irradiation.

An Actinide Complex with a Nucleophilic Allenylidene Ligand.

The reaction of [Cp3Th(3,3-diphenylcyclopropenyl)] (Cp = η5-C5H5) with 1 equiv of lithium diisopropylamide (LDA) results in cyclopropenyl ring opening and formation of the thorium allenylidene complex, [Li(Et2O)2][Cp3Th(CCCPh2)] ([Li(Et2O)2][1]), in good yield. Additionally, deprotonation of [Cp3Th(3,3-diphenylcyclopropenyl)] with 1 equiv of LDA, in the presence of 12-crown-4 or 2.2.2-cryptand, results in the formation of discrete cation/anion pairs, [Li(12-crown-4)(THF)][Cp3Th(CCCPh2)] ([Li(12-crown-4)(THF)][1]) and [Li(2.2.2-cryptand)][Cp3Th(CCCPh2)] ([Li(2.2.2-cryptand)][1]), respectively. Interestingly, the complex [Li(Et2O)2][1] undergoes dimerization upon standing at room temperature, resulting in the formation of [Cp2Th(μ:η1:η3-CCCPh2)]2 (2), via loss of LiCp. The reaction of [Li(Et2O)2][1] with MeI results in electrophilic attack at the Cγ carbon atom, leading to the formation of a thorium acetylide complex, [Cp3Th(C≡CC(Me)Ph2)] (3), which can be isolated in 83% yield upon workup, whereas the reaction of [Li(Et2O)2][1] with benzophenone results in the formation of 1,1,4,4-tetraphenylbutatriene (4) in 99% yield, according to integration against an internal standard. Density functional theory (DFT) calculations performed on [1]- and 2 reveal significant electron delocalization across the allenylidene ligand. Additionally, calculations of the 13C NMR chemical shifts for the Cα, Cβ, and Cγ nuclei of the allenylidene ligand were in good agreement with the experimental shifts. The calculations reveal modest deshielding induced by spin-orbital effects originating at Th due to the involvement of the 5f orbitals in the Th-C bonds. According to a DFT analysis, the cyclopropenyl ring-opening reaction proceeds via [Cp3Th(η1-3,3-Ph2-cyclo-C3)]- (IM), which features a carbanion character at Cβ.

The role of short-chain fatty acid metabolism in the pathogenesis, diagnosis and treatment of cancer

Short-chain fatty acids (SCFAs), which are saturated fatty acids consisting of six or fewer carbon atoms, have been found to be closely associated with the biological behavior of malignant tumors. This manuscript provides a comprehensive review on the role of SCFAs in regulating cell cycle, apoptosis, tumor angiogenesis, epithelial-mesenchymal transition, protein regulatory pathways, and histone regulation in promoting the development of malignant tumors. Furthermore, we discuss the potential therapeutic strategies targeting SCFAs for treating malignant tumors. This review offers a theoretical foundation for investigating the mechanisms by which SCFAs impact malignant tumors and provides insights into developing novel treatment targets.

Insight into the Reversible Hydrogen Storage of Titanium-Decorated Boron-Doped C20 Fullerene: A Theoretical Prediction

Hydrogen storage has been a bottleneck factor for the application of hydrogen energy. Hydrogen storage capacity for titanium-decorated boron-doped C20 fullerenes has been investigated using the density functional theory. Different boron-doped C20 fullerene absorbents are examined to avoid titanium atom clustering. According to our research, with three carbon atoms in the pentagonal ring replaced by boron atoms, the binding interaction between the Ti atom and C20 fullerene is stronger than the cohesive energy of titanium. The calculated results revealed that one Ti atom can reversibly adsorb four H2 molecules with an average adsorption energy of −1.52 eV and an average desorption temperature of 522.5 K. The stability of the best absorbent structure with a gravimetric density of 4.68 wt% has been confirmed by ab initio molecular dynamics simulations. These findings suggest that titanium-decorated boron-doped C20 fullerenes could be considered as a potential candidate for hydrogen storage devices.

Silk Fibroin-Based Multiple-Shape-Memory Organohydrogels.

Organohydrogels (OHGs) are intriguing materials due to their unique composition of both hydrophilic and hydrophobic domains. This antagonistic nature endows the OHGs with several remarkable properties, making them highly versatile for various applications. We present here a simple and inexpensive approach to fabricate silk fibroin (SF)-based OHGs with multistage switching mechanics and viscoelasticity. The continuous hydrophilic phase of the OHG precursor consists of an aqueous SF solution, while the hydrophobic droplet phase consists of a crystallizable n-octadecyl acrylate (C18A) monomer and several long-chain saturated hydrocarbons (HCs) with various chain lengths between 14 and 32 carbon atoms, namely, n-tetradecane, n-octadecane, n-docosane, n-dotriacontane, and 1-docosanol. After the addition of a C18A/HC mixture containing Irgacure photoinitiator into the continuous aqueous SF phase under stirring, a stable oil-in-water emulsion was obtained, which was then photopolymerized at 23 ± 2 °C to obtain nonswelling OHGs with multiple-shape-memory behavior. By changing the chain length and mass proportion of HCs, a series of OHGs with tunable transition temperatures could be obtained, meeting various applications. OHGs containing dimer, trimer, and quadruple combinations of in situ-formed poly(C18A) and HC microinclusions exhibit effective triple- or quintuple-shape memory whose shape-recovery temperatures could be adjusted over a wide range, e.g., between 7 and 70 °C.

Fluorine containing diamond-like carbon coatings

Fluorine containing diamond-like carbon (DLC) coatings were obtained by CVD deposition using the destruction of gaseous hydrocarbons by a high-energy ion source with an anode layer. The chemical composition, structure, surface energy, mechano-tribological characteristics of the synthesized thin-film material were studied. It has been shown that the fluorine content in the deposited coatings reaches 31 at.%. It has been established that the presence of fluorine in the DLC coating promotes the formation of nanodispersed graphite-like structures. Fluorine containing coatings with a high content of sp2 hybridized carbon atoms and graphite fragments show a decrease in hardness. Such coatings have a very low coefficient of friction at the level of 0.03–0.07 due to the low surface energy, which can be reduced by 1.5 times compared to pure DLC. It has been established that different fluorine contents in thin-film diamond-like carbon material have different effects on the interaction of the DLC coating with polar/non-polar dielectrics. The research results can be used for the technology of producing solid lubricants in friction units of machines and mechanisms, and are also of interest for medicine, the food industry, the production of plastics, and chemical fibers as chemically inert and corrosion-resistant coatings.

Asymmetrically Coordinated Cu Dual-Atom-Sites Enables Selective CO2 Electroreduction to Ethanol.

Electrochemical reduction of CO2 (CO2RR) to value-added liquid fuels is a highly attractive solution for carbon-neutral recycling, especially for C2+ products. However, the selectivity control to preferable products is a great challenge due to the complex multi-electron proton transfer process. In this work, a series of Cu atomic dispersed catalysts are synthesized by regulating the coordination structures to optimize the CO2RR selectivity. Cu2-SNC catalyst with a uniquely asymmetrical coordinated CuN2-CuNS site shows high ethanol selective with the FE of 62.6% at -0.8V versus RHE and 60.2% at 0.9V versus RHE in H-Cell and Flow-Cell test, respectively. Besides, the nest-like structure of Cu2-SNC is beneficial to the mass transfer process and the selection of catalytic products. In situ experiments and theory calculations reveal the reaction mechanisms of such high selectivity of ethanol. The S atoms weaken the bonding ability of the adjacent Cu to the carbon atom, which accelerates the selection from *CHCOH to generate *CHCHOH, resulting in the high selectivity of ethanol. This work indicates a promising strategy in the rational design of asymmetrically coordinated single, dual, or tri-atom catalysts and provides a candidate material for CO2RR to produce ethanol.

One-step synthesis of [15]paracyclophane and [16]paracyclophane via Pd-catalyzed C(sp2)–C(sp3) coupling and the cyclohexane-encapsulating crystal structure of [16]paracyclophane

Abstract Macrocycles consisting of methylene-bridged aromatic rings had been synthesized by aromatic electrophilic substitution reactions, thus limiting the substrates to electron-rich aromatic compounds. In this work, we developed a novel method for 1-step synthesis of [15]paracyclophane (PCP) and [16]PCP by the self-condensation of 4-bromobenzyl bromide via a Pd-catalyzed desulfinative coupling reaction between C(sp2) and C(sp3) carbon atoms. In the crystal structure, [16]PCP encapsulated cyclohexane and formed a 1D columnar structure

Radical Polarity.

The polarity of a radical intermediate profoundly impacts its reactivity and selectivity. To quantify this influence and predict its effects, the electrophilicity/nucleophilicity of >500 radicals has been calculated. This database of open-shell species entails frequently encountered synthetic intermediates, including radicals centered at sp3, sp2, and sp hybridized carbon atoms or various heteroatoms (O, N, S, P, B, Si, X). Importantly, these computationally determined polarities have been experimentally validated for electronically diverse sets of >50 C-centered radicals, as well as N- and O- centered radicals. High correlations are measured between calculated polarity and quantified reactivity, as well as within parallel sets of competition experiments (across different radical types and reaction classes). These multipronged analyses show a strong relationship between the computed electrophilicity, ω, of a radical and its relative reactivity (krel vs Δω slopes up to 40; showing mere Δω of 0.1 eV affords up to 4-fold rate enhancement). We expect this experimentally validated database will enable reactivity and selectivity prediction (by harnessing polarity-matched rate enhancement) and assist with troubleshooting in synthetic reaction development.

Zirconium-doped ultrathin copper nanowires for C1 and C2+ products in electrochemical CO2 reduction reaction

Cu-based nanostructures have garnered significant attention in the field of electrochemical carbon dioxide reduction (eCO2R), due to their significant activity and ability to produce a variety of value-added hydrocarbons and oxygenates. Current research efforts focus on steering eCO2R towards the formation of multi-carbon (C2+) products and elucidating the complex mechanisms of C-C coupling. One promising approach involves transition metals into Cu nanostructures. This study computationally investigates the impact of trace Zr atom doping on Cu nanostructures, specifically at the interfaces of (100) and (110) surfaces of ultrathin Cu nanowires. Our findings reveal that Zr dopants are energetically favourable and facilitate charge transfer to adjacent Cu atoms, thereby reducing the activation barriers for C-C coupling and enhancing the formation of C1 and C2 hydrocarbons. Additionally, the Zr-O interaction weakens the C-O bond, promoting C-O bond cleavage. The formation of C3 products, and the selectivity between hydrocarbons and oxygenates, are influenced by the hydrogenation sequence on different carbon atoms.

High-Throughput RPLC-MS/MS Quantification of Short- and Medium-Chain Fatty Acids.

Short- and medium-chain fatty acids (SMCFA) are monocarboxylic acids with a carbon chain length of 1-12 carbon atoms. They are mainly produced in humans by the gut microbiota, play crucial metabolic roles, are vital for intestinal health, and have multifaceted impact on immune and neurological functions. Accurate detection and quantification of SMCFA in different human biofluids is achieved using 3-nitro phenylhydrazine (3-NPH) derivatization of the free fatty acids followed by reverse phase liquid chromatography (RPLC) separation and detection by tandem mass spectrometry (MS/MS). Here, we describe the simultaneous measurement of 14 SMCFA and lactate in detail. All 3-NPH-SMCFA-hydrazones are separated in less than 5min with an 8-min total run time (injection-to-injection). Linear dynamic range over 0.1-500μM is achieved for most SCFAs, while it is 0.05-100μM for MCFAs. Validation of the procedure depicts good linearity (R2>0.98) and repeatability (CV≤20%). The lower limit of detection (LLOD) is 10-30nM. The lower limit of quantification (LLOQ) is 50-100nM for most analytes, while it is 0.5μM for acetate. In conclusion, the method offers several benefits compared to alternative methods regarding throughput, selectivity, sensitivity, and robustness.

Chiral Nanostructured Ag Films for Multicarbon Products from CO2 Electroreduction.

The formation of multicarbon products from CO2 electroreduction is challenging on materials other than Cu-based catalysts. Ag has been known to be a typical metal catalyst, producing CO in CO2 electroreduction. The formation of C2+ products by Ag has never been reported because the carbon-carbon (C-C) coupling is an unfavorable process due to the high reaction barrier energy of *OCCO. Here, we propose that the chirality-induced spin polarization of chiral nanostructured Ag films (CNAFs) can promote the formation of triplet OCCO by regulating its parallel electron spin alignment, and the helical lattice distortion of nanostructures can decrease the reaction energy of *OCCO, which triggers C-C coupling and promotes subsequent *OCCO hydrogenation to facilitate the generation of C2+ products. The CNAFs with helically lattice-distorted nanoflakes were fabricated via electrodeposition using phenylalanine as the symmetry-breaking agent. C2+ products (C2H4, C2H6, C3H8, C2H5OH, and CH3COOH) with a Faradaic efficiency of ∼4.7% and a current density of ∼22 mA/cm2 were generated in KHCO3 electrolytes under 12.5 atm of CO2 (g). Our findings propose that the chiral nanostructured materials can regulate the multifunctionality of catalytic performance in the catalytic reactions with triplet intermediates and products.

Preparation and ferroelectric properties of metal-organic frame lithium ion liquid crystal composites

ABSTRACT Two series of lithium ion liquid-crystalline composites (LCCs) containing metal-organic frame (MOF) materials were fabricated via a self-assembly process by use of poly(4-styrenesulfonic acid) lithium polymers, a cholesteryl-based liquid-crystalline monomer with terminal sulphonic acid group, and Fe-MIL-53_NH2. The chemical structure, chiral smectic C mesophase and ferroelectric property of the LCCs were characterised by various instruments, and the effect of liquid crystal monomer and lithium polymers on the ferroelectric property were investigated. The cholesteryl-based liquid crystal monomer presents a dominant role in the ferroelectric property of the LCCs, in which the asymmetric carbon atoms are responsible for the spontaneous polarisation. For the LCCs, the mechanical properties and porous loading characteristics of liquid crystal polymer are improved by the MOF materials, and the lithium-ion polymer connects the liquid crystal monomer with the MOF by ionic bond and improves the polarity of the material. When the electric field changed from −10 V and 10 V, the maximum residual polarisation strength (Pr) of the LCCs reached 74.82 nC/cm2. Because the LCCs showed excellent ferroelectric and mechanical properties, it has some potentials of application in the field of ferroelectric materials.

Metal-Cation-Induced Tiny Ripple on Graphene

Ripples on graphene play a crucial role in manipulating its physical and chemical properties. However, producing ripples, especially at the nanoscale, remains challenging with current experimental methods. In this study, we report that tiny ripples in graphene can be generated by the adsorption of a single metal cation (Na+, K+, Mg2+, Ca2+, Cu2+, Fe3+) onto a graphene sheet, based on the density functional theory calculations. We attribute this to the cation–π interaction between the metal cation and the aromatic rings on the graphene surface, which makes the carbon atoms closer to metal ions, causing deformation of the graphene sheet, especially in the out-of-plane direction, thereby creating ripples. The equivalent pressures applied to graphene sheets in out-of-plane direction, generated by metal cation–π interactions, reach magnitudes on the order of gigapascals (GPa). More importantly, the electronic and mechanical properties of graphene sheets are modified by the adsorption of various metal cations, resulting in opened bandgaps and enhanced rigidity characterized by a higher elastic modulus. These findings show great potential for applications for producing ripples at the nanoscale in graphene through the regulation of metal cation adsorption.

Molecular dynamics simulations of lipid composition and its impact on structural and dynamic properties of skin membrane

The stratum corneum (SC) plays the most important role in the absorption of topical and transdermal drugs. In this study, we developed a multi-layered SC model using coarse-grained molecular dynamics (CGMD) simulations of ceramides, cholesterol, and fatty acids in equimolar proportions, starting from two different initial configurations. In the first approach, all ceramide molecules were initially in the hairpin conformation, and the membrane bilayers were pre-formed. In the second approach, ceramide molecules were introduced in either the hairpin or splayed conformation, with the lipid molecules randomly oriented at the start of the simulation. The aim was to evaluate the effects of lipid chain length on the structural and dynamic properties of SC. By incorporating ceramides and fatty acids of different chain lengths, we simulated the SC membrane in healthy and diseased states. We calculated key structural properties including the thickness, normalized lipid area, lipid tail order parameters, and spatial ordering of the lipids from each system. The results showed that systems with higher ordering and structural integrity contained an equimolar ratio of ceramides (chain length of 24 carbon atoms), fatty acids with chain lengths ≥ of 20 carbon atoms, and cholesterol. In these systems, strong apolar interactions between the ceramide and fatty acid long acyl chains restricted the mobility of the lipid molecules, thereby maintaining a compact lipid headgroup region and high order in the lipid tail region. The simulations also revealed distinct flip-flop mechanisms for cholesterol and fatty acid within the multi-layered membrane. Cholesterol is mostly diffused through the tail-tail interface region of the membrane and could flip-flop in the same bilayer. In contrast, fatty acids flip-flopped between adjacent leaflets of two bilayers in which the tails crossed the thinner headgroup region of the membrane. To conclude, our SC model provides mechanistic insights into lipid mobility and is flexible in its design and composition of different lipids, enabling studies of varying skin conditions.