Alkane Chain Research Articles

Washable Superhydrophobic Cotton Fabric with Photothermal Self-Healing Performance Based on Nanocrystal-MXene.

Superhydrophobic fabrics suffer from being commonly penetrated by moisture after laundering, seriously deteriorating their water repellency after air drying. Numerous researchers have successfully recovered superhydrophobicity by drying in fluid ovens; however, high energy consumption and equipment dependence limit practical applications. Herein, the superhydrophobic photothermal self-healing cotton fabric (SPS cotton fabric) was fabricated by depositing a composite layer of cellulose nanocrystal-MXene (C-MXene) and polyacrylate (PA) coatings on the cotton cloth. Superior photothermal conversion of the SPS cotton fabric performance enables its 10.5-56.8 °C greater temperature than that of the pure hydrophobic cotton fabric under different simulated solar light intensities. After washing, the SPS cotton fabric can spontaneously restore superhydrophobicity with ≈100% efficiency by 30 mW·cm-2 solar light irradiation; in contrast, the single superhydrophobic fabrics recover only ≈71.2%. Even after 10 washing cycles, the recovery efficiency of the SPS cotton fabric only decreases by 0.1%, exhibiting excellent laundering durability. The SPS cotton fabric can retain ultralong time antifrosting (2760 s) and antifreezing (4080 s) capacities due to sustainable water repellency. Remarkably, the excellent self-healing capability of the SPS cotton fabric is attributed to the fact that the coiled nonpolar alkane chains can be restored to a straight state by autothermal drive, confirmed through element analyses and molecular dynamics simulations.

Evaluation of the alkyl chain length and photocatalytic antibacterial performance of cation g-C3N4.

Several cation graphite carbon nitrides (g-C3N4-(CH2)n-ImI+) were synthesized by chemically attaching imidazolium appended alkane chains with different lengths (n = 2, 4, 8, 12 and 16) to g-C3N4. The introduction of a cation segment potentially improved the interaction between the carbon material and Gram negative (MDR-A. baumannii) and Gram positive (S. aureus) bacteria as characterized by ζ potential measurement. Short alkane chain (carbon numbers of 2, 4 and 8) carbon materials displayed relatively stronger bacterial interactions compared to long alkane chain bearing ones (n = 12 and 16). In addition, short chain carbon materials (g-C3N4-(CH2)4-ImI+) displayed relatively higher photocatalytic reactive oxygen species (1O2, ˙O2- and ˙OH) production efficiency. Bacterial interaction and ROS production efficiency synergistically contribute to photocatalytic antibacterial performance. The current data revealed that g-C3N4 with short flexible cations attached exhibited bacterial interaction and ROS production. Among these synthesized materials, g-C3N4-(CH2)4-ImI+ exhibited the most pronounced photocatalytic antibacterial efficiency (>99%).

Towards continuous Rh-hydroformylation of long chain alkenes: handling methodology for the long-term stability of Biphephos in a continuous reactor with an attached membrane separation unit

Biphephos is known for its high activity and linear selectivity in Rh-catalyzed alkene hydroformylation. Key parameters, essential to maintain the long-term stability of Biphephos in the hydroformylation reaction system have been elucidated.

Flexible PVDF-based dielectric composites prepared by surface modification of BaTiO3 with fluorosilanes of varying alkane chain lengths

Flexible PVDF-based dielectric composites prepared by surface modification of BaTiO3 with fluorosilanes of varying alkane chain lengths

Molecular Dynamics Simulation on the Conformational Change of a pH-Switchable Lipid.

pH-sensitive lipids are important components of lipid nanoparticles, which enable the targeted delivery and controlled release of drugs. Understanding the mechanism of pH-triggered drug release at the molecular level is important for the rational design of ionizable lipids. Based on a recently reported pH-switchable lipid, named SL2, molecular dynamics (MD) simulations were employed to explore the microscopic mechanism behind the membrane destabilization induced by the conformational change of pH-switchable lipids. The simulated results showed that, at neutral pH, the neutral SL2 lipids assembled with other components (helper lipids and cholesterol) to form a structurally ordered bilayer structure. At this moment, the two hydrocarbon chains of SL2 were closely aligned and inserted in an orderly manner inside of the membrane. With a decrease in pH, the protonation of the pyridinium ring caused a large degree of molecular structural change. The pyridinium ring preferred to form intramolecular H-bonds with the methoxy groups and intermolecular H-bonds with water, resulting in the flip of the pyridinium ring. Meanwhile, due to the structural flip, the two alkane chains showed a more open state, which perturbed the arrangement of molecules within the membrane. The perturbations caused local collapse of the membrane and the formation of water molecule channels, which contributed to the pH-induced drug release. Our results verified the experimentally proposed mechanism at the molecular level and provided more complementary information, which are expected to have deeper insights into the pH-triggered drug release.

Reductive Zincke Reaction: Opening of Pyridinium Rings to δ-Amino Ketones via Transfer Hydrogenation.

The Zincke reaction and Birch reduction have been one of the few reactions that allow for ring opening of pyridines ever since the discovery of pyridine more than a century ago. This paper presents a new addition to the list of pyridine ring-opening reactions, reductive Zincke reaction, which affords saturated δ-amino ketones. Under the catalysis of a simple rhodium complex, pyridinium salts with diverse substituents are reduced with formic acid, ring-opened with water, transaminated with a secondary amine and further reduced to afford a wide range of δ-amino ketones, including those in which the alkane chain of the ketones is selectively deuterated or fluorinated. The applicability of the reaction is exemplified by the synthesis of drug analogues and late-stage modification of drug molecules.

Intrinsic Multicolor Emissive Aliphatic Linear Polyphosphate Esters From the Charge-Transfer-Induced Enhanced Spatial Electronic Communication.

Unconventional fluorescent polymers are attracting increasing attention because of their excellent biocompatibility and wide applications. However, these polymers typically exhibit weak long-wavelength emission. Herein, three novel aliphatic linear polyphosphate esters are prepared via a one-pot polycondensation reaction. Such polymers can generate strong blue, green, yellow, and red fluorescence under different excitations. Experimental and theoretical results showed that the cluster of C═C and phosphate ester groups attracted the negative charge of isolated functional groups, and the alkane chains and hydrogen atoms also provided a negative charge for spatial electronic communication. Then, intrinsic fluorescence arises from the charge-transfer-induced enhanced spatial electronic communication. Additionally, these polymers show potential applications in fluorescence film, ion detection, bacteria imaging, and visualization of the NaCl crystallization process. This work provides a universal design strategy for developing strong long-wavelength emissive polymers and gains new insight into intrinsic emission mechanisms.

Enhanced Performance and Stability of CsPbBr3 Perovskite Solar Cells Using Trioctylphosphine Oxide Additive.

This study investigates the application of trioctylphosphine oxide (TOPO) and triphenylphosphine oxide (TPPO) as an additive to enhance the performance of all-inorganic CsPbBr3 perovskite solar cells (PSCs). The addition of TOPO and TPPO passivates surface defects, increases grain size, and reduces surface trap states, leading to better light absorption and accelerated carrier transport. These modifications lead to an optimized energy level distribution, resulting in a significant increase in power conversion efficiency from 5.14 to 9.21% with TOPO and from 5.14% to 7.28% with TPPO. Furthermore, the long alkyl chains in TOPO provide effective isolation from air and water, significantly enhancing device stability for over 2400 h without packaging. The findings demonstrate that oxygen phosphine additives with long alkane chains are more effective in improving PSCs than those with aromatic hydrocarbons, offering new insights for the use of passivators in perovskite solar cells.

An approach for preparing multifunctional cellulose fabrics with hydrophilic-hydrophobic flexible modulation, salt-free dyeing and antibacterial performance.

A straightforward and effective approach was introduced for creating a multifunctional cellulose fabric in this paper. The epoxy groups in epoxidized soybean oil participated in ring-opening reactions with hydroxyl groups present in cellulose fibers and amino groups found in polyhexamethylene guanidine hydrochloride, respectively, under alkaline conditions. Polyhexamethylene guanidine hydrochloride could introduce cationic groups, while epoxidized soybean oil could contribute hydrophobic alkane chains. The multifunctional cotton fabrics were prepared by the modifying agent system, which possessed antibacterial properties and exhibited salt-free dyeability. Furthermore, the hydrophilicity and hydrophobicity of these cellulose fabrics could be adjusted by varying the concentration of the modification solution. The modified cotton was characterized by techniques such as Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and X-ray diffraction. The dyeing performance, hydrophobic characteristics, and antibacterial efficacy of the modified cotton fiber were assessed through a series of tests. When the modified cotton fabrics were dyed with reactive dyes without salt, the dye exhaustion rate and overall dye utilization rate achieved values of 92.14 % and 86.85 %, respectively. Additionally, the colorfastness and uniformity of dyed cotton fabrics were excellent. The hydrophobic cotton had a static water contact angle measuring 136.3°. Notably, the chemical modification method was simple and eco-friendly.

Cuboidal molybdenum sulfur cluster as a platform to construct novel catalyst for propane dehydrogenation

Growing demand of short chain olefins such as propylene for plastic production drives the development of high performing catalysts for propane dehydrogenation (PDH). Here, a confinement strategy originating from metal-sulfur clusters was employed to fabricate defective MoPtSx phase via anchoring by coordinatively unsaturated Al sites present on alumina, followed by reduction under H2 flow at high temperature. This catalyst with a low Pt content exhibits great ability for C–H activation with high intrinsic activity and facile propylene desorption in PDH reaction. More importantly, this catalyst shows excellent stability during long-term tests with both stable conversion and selectivity. Through combined X-ray absorption spectroscopy, electron microscopy and electron paramagnetic resonance measurements it could be affirmed that the isolated and electron-enriched Pt sites as well as their proximity to adjacent sulfur vacancies is vital for the first and second C–H bond activation, and suppressing of C–C cleavage which otherwise lead to coking.

The Entropy of Mixing in Self-Assembly and the Role of Surface Tension in Modeling the Critical Micelle Concentration

A theory for the micelle formation of nonionic head-tail amphiphiles (detergents) in aqueous solutions is derived based on the traditional molecular thermodynamic modeling approach and a variant of the Flory–Huggins theory that goes beyond lattice models. The theory is used to analyze experimental values for the critical micelle concentration of n-alkyl-ß-D-maltosides within a mass action model. To correlate those parts of the micellization free energy, which depend on the transfer of hydrophobic molecule parts into the aqueous phase, with molecular surfaces, known data for the solubility of alkanes in water are reanalyzed. The correct surface tension to be used in connection with the solvent-excluded surface of the alky tail is ~30 mN/m. This value is smaller than the measured surface tension of a macroscopic alkane–water interface, because the transfer free energy contains a contribution from the incorporation of the alkane or alkyl chain into water, representing the change in free volume in the aqueous phase. The Flory–Huggins theory works well, if one takes into account the difference in liberation free energy between micelles and monomers, which can be described in terms of the aggregation number as well as the thermal de Broglie wavelength and the free volume of the detergent monomer.

Remote Catalytic C(sp3)-H Alkylation via Relayed Carbenoid Transfer upon Olefin Chain Walking.

Transition metal carbenes have emerged as versatile intermediates for various types of alkylations. While reactions of metal carbene species with alkenes have been extensively studied, most examples focus on cyclopropanation and allylic C-H insertion. Herein, we present the first example of a catalytic strategy for the carbene-involved regioselective remote C-H alkylation of internal olefins by synergistically combining two iridium-mediated reactivities of olefin chain walking and carbenoid migratory insertion. The present method, utilizing sulfoxonium ylides as a bench-stable robust carbene precursor, was found to be effective for a series of olefins tethered with alkyl chains, heteroatom substituents, and complex biorelevant moieties. Combined experimental and computational studies revealed that reversible iridium hydride-mediated olefin chain walking proceeds to lead to a terminal alkyl-Ir intermediate, which then forms a carbenoid species for the final migratory insertion, resulting in regioselective terminal-alkylated products.

Arabidopsis DREB26/ERF12 and its close relatives regulate cuticular wax biosynthesis under drought stress condition.

Land plants have evolved a hydrophobic cuticle on the surface of aerial organs as an adaptation to ensure survival in terrestrial environments. Cuticle is mainly composed of lipids, namely cutin and intracuticular wax, with epicuticular wax deposited on plant surface. The composition and permeability of cuticle have a large influence on its ability to protect plants against drought stress. However, the regulatory mechanisms underlying cuticular wax biosynthesis in response to drought stress have not been fully elucidated. Here, we identified three AP2/ERF transcription factors (DREB26/ERF12, ERF13 and ERF14) involved in the regulation of water permeability of the plant surface. Transmission electron microscopy revealed thicker cuticle on the leaves of DREB26-overexpressing (DREB26OX) plants, and thinner cuticle on the leaves of transgenic plants expressing SRDX repression domain-fused DREB26 (DREB26SR). Genes involved in cuticular wax formation were upregulated in DREB26OX and downregulated in DREB26SR. The levels of very-long chain (VLC) alkanes, which are a major wax component, increased in DREB26OX leaves and decreased in DREB26SR leaves. Under dehydration stress, water loss was reduced in DREB26OX and increased in DREB26SR. The erf12/13/14 triple mutant showed delayed growth, decreased leaf water content, and reduced drought-inducible VLC alkane accumulation. Taken together, our results indicate that the DREB26/ERF12 and its closed family members, ERF13 and ERF14, play an important role in cuticular wax biosynthesis in response to drought stress. The complex transcriptional cascade involved in the regulation of cuticular wax biosynthesis under drought stress conditions is discussed.

Non‐Oxidative Dehydroaromatization of Linear Alkanes on Intermetallic Nanoparticles

AbstractThere has been significant interest in developing new catalytic systems to convert linear chain alkanes into olefins and aromatics. In the case of higher alkanes (≥C6), the production of aromatic compounds such as benzene‐toluene‐xylenes is highly desirable. However, as the length of the carbon chain increases, the dehydrogenation process becomes more complex, not only due to the challenges of C−H activation but also the need for selectivity towards the desired products by the possibility of side reactions such as isomerization and cracking. Here, we present a detailed analysis of the dehydroaromatization of n‐hexane, n‐heptane, and n‐octane, using PtSn intermetallic nanoparticles supported on SBA‐15 as the catalyst. Through in situ spectroscopic and kinetic analysis, we have probed the reaction kinetics and catalyst deactivation, and provided a mechanistic understanding of the dehydroaromatization process on the surface of the PtSn intermetallic nanoparticles. Introducing Sn has been shown to be crucial not only for enhancement of catalytic activity, but also for higher aromatics selectivity and stability on stream. Furthermore, the analysis of dehydroaromatization reaction rates of reactant and possible intermediates indicates that the dehydroaromatization of n‐hexane to benzene likely proceeds through initial dehydrogenation steps followed by ring closing.

Epoxidized cardanol oleate (ECD-OA) as an effective biobased chain extender of polylactic acid (PLA)

Moisture exposure during polyester processing can lead to degradation, resulting in the formation of carboxyl and hydroxyl end-groups. To preserve mechanical properties, thorough drying and the use of chain extenders like epoxy acrylates and isocyanates during extrusion are crucial for maintaining or enhancing molecular weight through in-situ reactions. Our study introduced epoxidized cardanol oleate (ECD-OA), containing epoxy and long-chain alkyl groups, as a potential chain extender, and compared its effectiveness with commercially available epoxidized cardanol glycidyl ether (cardolite NC514). Compared to neat PLA without chain extension, the addition of 1 phr ECD-OA resulted in an increase in the molecular weight (Mw) of PLA from 15.3 × 104 g/mol to 17.1 × 104 g/mol, demonstrating a chain extension efficiency of 11.8 %. The melt flow rate of PLA decreased from 9.9 g/10 min to 5.0 g/10 min, and the initial thermal degradation temperature of PLA increased by 5.7 °C. Upon chain extension, there was a substantial increase in both the elongation at break and tear resistance of the PLA film. The results demonstrate that ECD-OA can extend PLA molecular chains through chemical reactions and promote entanglement with the long alkane chain, consequently enhancing the mechanical and thermal properties of PLA. Due to the enzyme's preference for biobased small molecules, the PLA film with the addition of a biobased chain extender is more prone to enzymatic degradation compared to neat PLA. To conclude, ECD-OA acts as a bio-based chain extender that improves the performance of PLA while also enhancing its biodegradability.

Effect of gas type on properties of anionic surfactant foam system

The foam drainage technique is considered to be a promising measure for solving the problem of liquid accumulation in natural gas wells and gathering pipelines. However, differences in gases can greatly affect the performance of surfactant foam, thus limiting the application of this technology. To elucidate the mechanism of natural gas components influencing foam properties, the interfacial properties of hydrocarbon gas-surfactant-water system were analyzed thermodynamically and kinetically by combining molecular dynamics simulations and foaming experiments. The results show that with the increasing alkane chain length, the foaming volume and half-life of the foam are gradually rising, while the gas–liquid interfacial tension is decreasing, which is consistent with the results of molecular dynamics simulations. Compared with air, hydrocarbon gases are more beneficial for foam generation and stabilization. The interfacial adsorption of alkane molecules and the interaction between alkanes and surfactants are the main factors affecting the interfacial tension and film stability of different systems.

Degradation of diesel fuel by Pseudomonas aeruginosa B031 with expression of the alkB gene in a column bioreactor

Diesel fuel pollutants contain toxic hydrocarbons dominated by aliphatic and aromatic hydrocarbons. Hydrocarbon pollutants can be degraded in an environmentally friendly manner through bioremediation using hydrocarbonoclastic bacteria, i.e., Pseudomonas aeruginosa B031, which harbors the alkB gene that encodes an alkane hydroxylase that degrades alkane chains in hydrocarbons. This study compared the ability and efficiency of P. aeruginosa B031 to degrade diesel pollutants in a batch system and a continuous system using a column bioreactor, as well as the expression of alkB. P. aeruginosa B031 could more efficiently degrade diesel fuel in a continuous system in a column bioreactor than in the batch system. The concentrations of phenol, total organic carbon, chemical oxygen demand, and biological oxygen demand in the column bioreactor underwent a greater decrease than those in the batch system, namely 1.5-fold, 1.7-fold, 1.4-fold, and 1.3-fold, respectively. The decrease in these concentrations was followed by changes in functional groups, as shown via Fourier transform infrared spectroscopy. The number of bacteria and the concentration of exopolysaccharide increased in the column bioreactor by 4-fold and 2.3-fold more than the increase in the batch system. The ability of P. aeruginosa B031 to degrade diesel fuel in the column bioreactor was also demonstrated by the higher expression of alkB than that in the control.

Experimental Study on the Thermal Behavior Characteristics of the Oxidative Spontaneous Combustion Process of Fischer–Tropsch Wax Residue

Coal-to-liquid technology is a key technology to ensuring national energy security, with the Fischer–Tropsch synthesis process at its core. However, in actual production, Fischer–Tropsch wax residue exhibits the characteristics of spontaneous combustion due to heat accumulation, posing a fire hazard when exposed to air for extended periods. This significantly threatens the safe production operations of coal-to-liquid chemical enterprises. This study primarily focuses on the experimental investigation of the oxidative spontaneous combustion process of three typical types of wax residues produced during Fischer–Tropsch synthesis. Differential Scanning Calorimetry (DSC) was used to test the thermal flow curves of the three wax residue samples. Kinetic analysis was performed using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods to calculate their apparent activation energy. This study analyzed the thermal behavior characteristics, exothermic properties, and kinetic parameters of three typical wax residue samples, exploring the ease of reaction between wax residues and oxygen and their tendency for spontaneous combustion. The results indicate that Wax Residue 1 is rich in low-carbon chain alkanes and olefins, Wax Residue 2 contains relatively fewer low-carbon chain alkanes and olefins, while Wax Residue 3 primarily consists of high-carbon chain alkanes and olefins. This leads to different thermal behavior characteristics among the three typical wax residue samples, with Wax Residue 1 having the lowest heat release and average apparent activation energy and Wax Residue 3 having the highest heat release and average apparent activation energy. These findings suggest that Wax Residue 1 has a higher tendency for spontaneous combustion. This research provides a scientific basis for the safety management of the coal chemical industry, and further exploration into the storage and handling methods of wax residues could reduce fire risks in the future.

Single‐Molecule Conductance of Staffanes

We report the first conductance measurements of [n]staffane oligomers in single‐molecule junctions. Our studies reveal two quantum transport characteristics unique to staffanes that emerge from their strained bicyclic structure. First, though staffanes are composed of weakly conjugated C‐C σ‐bonds, staffanes carry a shallower conductance decay value (β = 0.84 ± 0.02 n‐1) than alkane chain analogs (β = 0.96 ± 0.03 n‐1) when measured with the scanning tunneling microscopy break junction (STM‐BJ) technique. Staffanes are more conductive than other σ‐bonded organic backbones in the literature on a per atom basis. Density functional theory calculations suggest staffane backbones are effective conduits for charge transport because their significant bicyclic ring strain destabilizes the HOMO‐2 energy, aligning it more closely with the Fermi energy as oligomer order increases. Second, the monostaffane is significantly lower conducting than expected. DFT calculations suggest that short monostaffanes sterically enforce insulating gauche interelectrode orientations over syn orientations. Meanwhile, [2‐5]staffane wires may accommodate axial mechanical strain by “rod‐bending”. These findings show for the first time how bicyclic ring strain can enhance charge transmission in saturated molecular wires. These studies showcase the STM‐BJ technique as a valuable tool for uncovering the stereoelectronic proclivities of molecules at material interfaces.

Single-Molecule Conductance of Staffanes.

We report the first conductance measurements of [n]staffane (bicyclopentane) oligomers in single-molecule junctions. Our studies reveal two quantum transport characteristics unique to staffanes that emerge from their strained bicyclic structure. First, though staffanes are composed of weakly conjugated C-C σ-bonds, staffanes carry a shallower conductance decay value (β=0.84±0.02 n-1) than alkane chain analogs (β=0.96±0.03 n-1) when measured with the scanning tunneling microscopy break junction (STM-BJ) technique. Staffanes are thus more conductive than other σ-bonded organic backbones reported in the literature on a per atom basis. Density functional theory (DFT) calculations suggest staffane backbones are more effective conduits for charge transport because their significant bicyclic ring strain destabilizes the HOMO-2 energy, aligning it more closely with the Fermi energy of gold electrodes as oligomer order increases. Second, the monostaffane is significantly lower conducting than expected. DFT calculations suggest that short monostaffanes sterically enforce insulating gauche interelectrode orientations over syn orientations; these steric effects are alleviated in longer staffanes. Moreover, we find that [2-5]staffane wires may accommodate axial mechanical strain by "rod-bending". These findings show for the first time how bicyclic ring strain can enhance charge transmission in saturated molecular wires. These studies showcase the STM-BJ technique as a valuable tool for uncovering the stereoelectronic proclivities of molecules at material interfaces.