Alkyl Chain Research Articles

Revealing the antioxidant properties of alkyl gallates: a novel approach through quantum chemical calculations and molecular docking.

This study investigates the antioxidant potential of alkyl gallates (C1-C10), focusing on the impact of alkyl chain length and solvent polarity on their antioxidant properties. Known for their biomedical relevance in mitigating oxidative stress, alkyl gallates' structure-activity relationships, particularly regarding chain length and environmental factors, still need to be explored. Key thermochemical parameters, including bond dissociation enthalpy (BDE), ionization potential (IP), proton affinity (PA), and electron transfer enthalpy (ETE), reveal that shorter alkyl chains (C1-C4) exhibit superior antioxidant activity. In contrast, longer chains (C5-C10) show reduced effectiveness due to steric hindrance and lower solubility in polar solvents. Molecular docking studies also demonstrated favorable binding interactions with vital biological targets, further reinforcing their antioxidant potential. Quantum chemical calculations were performed using Gaussian 16 with the B3LYP/6-311G(dp) basis set for geometry optimizations. Solvent effects were modeled using the integral equation formalism-polarized continuum model (IEF-PCM). Molecular docking studies were conducted using AutoDockTools 4.2, targeting Tyrosine Kinase Hck, Heme Oxygenase, and Human Serum Albumin to evaluate fundamental binding interactions. These computational methods provided insights into alkyl gallates' chemical reactivity and antioxidant efficiency, allowing for the rational design of more potent antioxidant compounds.

Investigation of the mechanism of [M-H]+ ion formation in photoionized N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione derivatives during higher order MSn high-resolution mass spectrometry.

The mechanism underlying dopant-assisted atmospheric pressure photoionization's (APPI) formation of ions is unclear and still under debate for many chemical classes. In this study, we reexamined the gas-phase reaction mechanisms responsible for the generation of [M-H]+ precursor ions, resulting from the loss of a single hydrogen atom, in a series of N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione (TPD) derivatives. Atmospheric pressure photoionization combined with higher order MS/MSn using high-resolution mass spectrometry (APPI-HR-CID-MSn) and electronic structure calculations using density functional theory were used to determine the chemical structure of observed [M-H]+ ions. As a result, the higher order MSn (n = 3) experiments revealed a reversed Diels-Alder fragmentation mechanism, leading to a common fragment ion at m/z 322 from the studied [M1-5-H]+ ion species. In addition, the calculation for two chemical structure models (N-alkyl-TPD1 and N-alkyl-TPD5) showed that the fragment structure, resulting from the removal of the hydrogen atom connected to the third carbon atom of the N-alkyl side chain, has a more stable cyclic form compared with the linear one. The proposed chemical structure of the N-alkyl TPD ion species, following the loss of a single hydrogen atom, was revealed during APPI-HR-CID-MSn (n= 3) experiments on the [M-H]+ species. Hydrogen radical (H•) abstraction from the alkyl side chain (e.g., hexyl, heptyl, octyl, 2-ethylhexyl, and nonyl) triggered a rearrangement in the radical cation structure of the N-alkyl-TPD derivatives, initiating cyclization and forming a six-membered ring that connects the oxygen atom to the third carbon atom in the alkyl chain. In addition, theoretical calculations supported the APPI-HR-CID-MSn (n = 3) experiments by demonstrating that the proposed chemical structure, resulting from the intramolecular cyclization of the N-alkyl-TPD ion species, was stable in the presence of chlorobenzene. These findings will aid the structural determination and elucidation of molecules with similar core structures.

The charge transport properties of dicyanomethylene-functionalised violanthrone derivatives

The study of organic small molecule semiconductor materials as active components of organic electronic devices continues to attract considerable attention due to the range of advantages these molecules can offer. Here, we report the synthesis of three dicyanomethylene-functionalised violanthrone derivatives (3a, 3b and 3c) featuring different alkyl substituents. It is found that the introduction of the electron-deficient dicyanomethylene groups significantly improves the optical absorption compared to their previously reported precursors 2a–c. All compounds are p-type semiconductors with low HOMO–LUMO gaps (≈1.25 eV). The hole mobilities, measured from fabricated organic field-effect transistors, range from 3.6 × 10−6 to 1.0 × 10−2 cm2 V−1 s−1. We found that the compounds featuring linear alkyl chains (3b and 3c) displayed a higher mobility compared to the one with branched alkyl chains, 3a. This could be the result of the more highly disordered packing arrangement of this molecule in the solid state, induced by the branched side chains that hinder the formation of π–π stacking interactions. The influence of dicyanomethylene groups on the charge transport properties was most clearly observed in compound 3b which has a 60-fold improvement in mobility compared to 2b. This study demonstrates that the choice of the solubilising group has a profound effect on the hole mobility on these organic semiconductors.

Dual Responsive Emulsions Based on Amphiphilic Elastin-like Polypeptide Bioconjugates.

To achieve the desired therapeutic response, drug delivery systems must ensure the controlled release of the loaded content at the targeted site. One possible strategy relies on the improvement of conventional drug delivery systems. To do so, smart polymers, able to change their behavior upon chemical, physical, or biological stimuli, can be used. In this context, this study aims to evaluate the potential of natural amphiphilic smart elastin-like polypeptides grafted with alkyl chains (ELP-g-Bu) to stabilize conventional oil-in-water emulsions and trigger the release of loaded molecules upon dual stimuli. With butyl pendant chains and methionine residues, the macromolecular surfactant ELP-g-Bu demonstrated a modification of physicochemical properties, looking at critical aggregation concentration, upon both temperature and oxidation stimuli. The macromolecular surfactant was then able to stabilize a paraffin-oil-in-water emulsion. The ELP-g-Bu emulsion presented a droplet size of 9 ± 1 μm and stability for at least a month at 4 and 25 °C. After successful loading of a fluorescent lipophilic molecule used as a drug model, a complete destabilization of the ELP-g-Bu emulsion and burst release of the content was achieved with thermal triggering at 42 °C. In oxidative conditions, a partial release was measured, which can be improved by increasing the number of oxidable thioether groups. Overall, these dually responsive amphiphilic ELP-g-Bu demonstrated their potential for smart-polymer-based drug delivery systems that can be promising for inflammatory disease treatment as increased temperature and radical oxygen species are present in such cases.

Construction of Luminescent Terpyridine-Based Metallo-Bowties with Alkyl Chain-Bridged Dimerized Building Blocks.

Numerous metallo-supramolecules with well-defined sizes and shapes have been successfully constructed via the strong coordination interaction between terpyridine (TPY) moieties and ruthenium cations. However, the pseudo-octahedral geometry of <TPY-Ru-TPY> unit hampers the luminescent properties of such metallo-architectures, thus limiting their applications as optical materials. To address this issue, we herein use a flexible alkyl chain to bridge TPY building blocks, replacing conventional <TPY-Ru-TPY> linkage. The introduction of alkyl chain guides the self-assembly into desired architecture while simultaneously eliminating the quenching effects typically associated with the <TPY-Ru-TPY> linkage. More importantly, this design strategy enables the precise construction of bowtie-shaped metallo-supramolecules with significantly enhanced emission. The incorporation of alkyl chain linkage not only maintains structural integrity but also enhances optical performance, making these metallo-supramolecular assemblies highly promising for applications in advanced photonic and luminescent materials. This study offers a versatile approach to construct complex metallo-supramolecular architectures with desired optical properties.

A Sucker-Reactor Polyoxometalate Assembled Superstructures for Efficient Photocatalytic Nitrogen Fixation.

Designing a reaction system that integrates reactant capture and transformation in an artificial photosynthesis system to achieve high reaction efficiency remains challenging. Here, an ionic liquid (IL) -polyoxometalate (POM) superstructure photocatalyst (P2HPMo) is reported, where the anisotropy of the superstructure is allowed by adjusting the alkyl chain lengths of ILs. Experimental data and theoretical simulation show that ILs and POM serve as the "sucker" and "reactor" of the reaction system to capture and transform the reactants, respectively. In particular, the addition of quaternary phosphorous IL cations is not only conducive to the adsorption of N2 but also effectively promotes the activation of N2 by manipulating the energy band and electronic structure. Consequently, the synthesized P2HPMo exhibits an ammonia synthesis rate of 98 µmol·gcat -1·h-1, which is one of the highest values available in a sacrificial agent-free system.

Modulating the Competition between Different Atoms to Form Halogen Bonds.

I and Br atoms are placed on opposite ends of a n-butyl group, with each allowed to form a halogen bond (XB) with NH3. DFT calculations show that the intrinsic preference of the nucleophile for the heavier I over Br can be reversed by the proper placement of substituents on the alkyl chain. A similar reversal occurs for NH2 and OH groups on the alkyl chain, where substituents make the O a better electron donor than N in an XB to an electrophilic ICCH. The highly mobile π-electron cloud of an aromatic ring makes such reversals much more difficult when the pair of competing atoms are placed on, or within, such a ring.

Thermoelectric Properties of Benzothieno-Benzothiophene Self-Assembled Monolayers in Molecular Junctions.

We report a combined experimental (C-AFM and SThM) and theoretical (DFT) study of the thermoelectric properties of molecular junctions made of self-assembled monolayers on Au of thiolated benzothieno-benzothiophene (BTBT) and alkylated BTBT derivatives (C8-BTBT-C8). We measure the thermal conductance per molecule at 15 and 8.8 pW/K, respectively, among the lowest values for molecular junctions so far reported (10-50 pW/K). The lower thermal conductance for C8-BTBT-C8 is consistent with two interfacial thermal resistances introduced by the alkyl chains, which reduce the phononic thermal transport in the molecular junction. The Seebeck coefficients are 36 and 245 μV/K, respectively, the latter due to the weak coupling of the core BTBT with the electrodes. We deduce a thermoelectric figure of merit ZT up to ≈10-4 for the BTBT molecular junctions at 300 K, on a par with the values reported for archetype molecular junctions (oligo(phenylene ethynylene) derivatives).

TVT-Based New Building Block with Enhanced π-Electron Delocalization for Efficient Non-Fused Photovoltaic Acceptor.

To address the high-cost issue that impedes the large-scale fabrication and industrialization of organic solar cells (OSCs), it is crucial to design low-cost photovoltaic materials with simplified synthesis procedures. In this study, a novel fully non-fused acceptor, ATVT-BO, featuring a triisopropylbenzene-substituted (E)-1,2-di(thiophen-2-yl)ethene (TVT) unit as the central core is designed and synthesized. A control acceptor, A4T-BO, with the same alkyl chains but a bithiophene central core, is also synthesized for comparison. Theoretical calculations and practical measurements reveal that compared to A4T-BO, the insertion of an ethylene bond in ATVT-BO enhances the molecular planarity and reduces the aromaticity, leading to enhanced π-electron delocalization and thus improved electron mobility and a red-shifted optical absorption spectrum. The 3D molecular packing mode of ATVT-BO, characterized by tight intermolecular interactions, also promotes efficient charge transport in OSCs. Consequently, when paired with the low-cost polymer PTVT-T, featuring an ester-substituted TVT structure, as the photoactive layer, the PTVT-T:ATVT-BO-based device achieves a remarkable power conversion efficiency of 14.8%, distinctly higher than that of PTVT-T:A4T-BO-based cell. The result highlights the significant potential of TVT units in creating both low-cost polymer donors and fully non-fused acceptors, which opens up new possibilities for designing low-cost photoactive materials in OSCs.

Development of Cyclometalated Iridium(III) Complexes of 2-Phenylbenzimidazole and Bipyridine Ligands for Selective Elimination of Gram-Positive Bacteria.

Herein, we have reported a series of cationic aggregation-induced emission (AIE) active iridium(III) complexes (Ir1-Ir5) of the type [Ir(C^N)2(N^N)]Cl, wherein C^N is a cyclometalating 2-phenylbenzimidazole ligand with varying alkyl chain lengths and N^N is a 2,2'-bipyridine ligand attached to bis-polyethylene glycol chains, for the treatment of bacterial infections. The AIE phenomenon of the complexes leveraged for detecting bacteria by fluorescence microscopy imaging that displayed a strong red emission in Gram-positive bacteria. The antibacterial activity of the complexes assessed against Gram-positive methicillin-sensitive S. aureus, methicillin-resistant S. aureus, E.faecium and E.faecalis and Gram-negative E. coli and P.aeruginosa bacteria of clinical interest. The complexes Ir2-Ir4 exerted potent antibacterial activity towards Gram-positive strains with low minimum inhibitory concentrations (MICs) values in the range of 1-9 μM, which is comparable to clinically approved antibiotic vancomycin. In contrast, these complexes were found to be inactive towards Gram-negative bacterial strains (MICs > 100 µM). The mechanism of antibacterial activity of the complexes implies that ROS generation, membrane depolarization and rupture are responsible for bacterial cell death. Further, the complexes Ir1-Ir3 were found to be low-toxic against human red blood cells and human embryonic kidney (HEK293) cells, indicating their potential for use as antibacterial agents.

A comprehensive study on the application properties of different soft, hard, and functional monomers to polyacrylate emulsion and water‐based inks

AbstractThe urge to protect the deteriorating ecosystem is compelling us to develop environmental‐friendly materials. In this paper, three different kinds of waterborne polyacrylate emulsions were synthesized with different hard, soft and hydroxyl‐containing functional monomers by semi‐continuous seed emulsion polymerization. Moreover, the influences of different monomers on the performances such as viscosity, adhesion, surface tension, particle size, stability, and contact angle were also investigated. Attractively, conclusions were deduced that with the growth of the monomer's alkyl chain length, the viscosity gradually increases and the surface tension gradually decreases. On the other hand, different functional monomers also have effect on the properties of the synthesized acrylic emulsions. Then the synthesized water‐based acrylic emulsions were used as binders for water‐based inks, the adhesion as well as initial dryness were tested and the recipe for water‐based ink with better performances was selected out. Our work maybe ignites a spark for the designation of acrylic emulsions for water‐based inks binders.

Disappearance of Odd-Even Effects at the Substrate Interface of n-Alkanes.

The physical and chemical properties of organic compounds having alkyl chains are frequently influenced by the parity of the chain length, which is known as the odd-even effect. Understanding the molecular origin of this phenomenon is particularly important for designing materials used in organic thin-film devices. In this work, we focus on thin films of n-alkanes as the simplest model to study the odd-even effect at the substrate interface and analyze the aggregation structure using p-polarized multiple-angle incidence resolution spectrometry in combination with grazing incidence X-ray diffraction. The spectroscopic analysis shows a pronounced odd-even alternation of the molecular tilt angles in the multilayer films. In addition, high-resolution Brewster-angle transmission spectroscopy reveals that the conformation of the methyl group highly depends on whether the carbon number is even or odd. In contrast to the multilayer films, the odd-even effects do not appear in the monolayer films. We demonstrate that, in other words, the interlayer interactions of the molecules are responsible for the odd-even effects. This study also highlights the first identification of the monolayer phase of n-alkanes by using grazing incidence X-ray diffraction in combination with high-resolution infrared spectroscopy. These results not only reveal the molecular origin for the odd-even effect of n-alkanes but also provide analytical techniques for discussing the monolayer structure of various alkylated compounds on a functional group basis.

Organic BODIPY based gels: Optical, electrochemical and self-assembly properties.

Two novel BODIPY dyes, BOC3 and BC12, were synthesized with variable alkyl chains at terminal amide functional units. BC12, featuring a longer alkyl chain (-C12H25), formed a gel compared to BOC3, which has a shorter alkyl chain (-CH2OCH3), due to supra molecular self-assembly in film. Both dyes exhibited absorption peaks around 530 nm in the visible region, with a red shift of about 30 nm in the film state, essential for organic electronic applications. Concentration variation studies revealed π-π stacking/aggregates in the solid state causing red shifts in absorption and emission. BC12 exhibited more significant red shifts in film compared to its solution state due to supra molecular self-assembly. Electronic structure analysis using density functional theories (BMK and O3LYP) showed better correlation with absorption using the O3LYP method. Both dyes displayed quasi-irreversible oxidation and reduction couples with suitable HOMO (5.46 eV) and LUMO (3.32 eV) energy levels for organic electronic applications. Transient photoluminescence studies indicated a longer lifetime for BC12 (5.28 ns) than BOC3 (4.50 ns), suggesting π-π aggregation and supra molecular self-assembly. BC12's gelation, attributed to its long alkyl chain and two-dimensional motifs of the BODIPY core, forms spherical-shaped nano networks.

Effect of Anchoring Unit, N-Alkyl Chain Length, and Thickness of Titanium Dioxide Layer on the Efficiency of Dye-Sensitized Solar Cells (DSSCs) and Tandem DSSCs

Effect of Anchoring Unit, <i>N</i>-Alkyl Chain Length, and Thickness of Titanium Dioxide Layer on the Efficiency of Dye-Sensitized Solar Cells (DSSCs) and Tandem DSSCs

Asymmetric Alkyl Chain Engineering for Efficient and Eco-Friendly Organic Photovoltaic Cells.

Recent advancements in organic photovoltaic (OPV) cells have resulted in power conversion efficiencies (PCEs) surpassing 20%. However, the use of halogen solvents in the fabrication of OPV cells raises concerns due to their potential environmental and health impacts. In this work, a novel non-fullerene small molecule acceptor BO-AM-4F, featuring an asymmetric alkyl chain design that includes a 2-butyloctyl and a unique 6-(hexylamino)-6-oxohexyl chain is synthesized. This design significantly improves molecular packing, crystallinity, and electrostatic potential distribution compared to the controlled acceptor DBO-4F, which possesses symmetric 2-butyloctyl chains. When combined with the polymer donor PBDB-TF and processed using the non-halogen solvent o-xylene, the BO-AM-4F-based OPV cell achieves an impressive PCE of 18.0%, surpassing the 16.6% PCE observed in the PBDB-TF:DBO-4F device. Furthermore, the PBDB-TF:BO-AM-4F system demonstrates enhanced photostability and thermal stability compared to its DBO-4F counterpart. These findings emphasize asymmetric alkyl chain engineering as an effective strategy for developing high-performance, environmentally friendly OPV materials. This represents a significant step towards sustainable OPV technology.

Ethanolamine and Vinyl–Ether Moieties in Brain Phospholipids Modulate Behavior in Rats

Plasmalogens are brain-enriched phospholipids with a vinyl–ether bond at the sn-1 position between the glycerol backbone and the alkyl chain. Previous studies have suggested that plasmalogens modulate locomotor activity, anxiety-like behavior, and cognitive functions in rodents; however, the specific moieties contributing to behavioral regulation are unknown. In this study, we examined the behavioral modulation induced by specific phospholipid moieties. To confirm the permeability of phospholipids in injected liposomes, we measured the fluorescence intensity following intravenous injection of liposomes containing ATTO 740-labeled dioleoylphosphatidylethanolamine. Then, we compared the behavioral effects following injection of liposomes composed of egg phosphatidylcholine (PC) and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (PE 18:0/22:6), PC 18:0/22:6, 1-(1Z-octadecenyl)-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (PE P-18:0/22:6), or PC P-18:0/22:6, into the tail vein of male rats. The time spent in the central region of the open field was significantly reduced after injection of PE 18:0/22:6, harboring an ester bond at sn-1 compared to controls. Furthermore, the discrimination ratio in the novel object recognition test was significantly higher in PC 18:0/22:6 compared to PE 18:0/22:6, suggesting that the substitution of ethanolamine with choline can enhance recognition memory. We demonstrate that the structures of the sn-1 bond and the hydrophilic moiety in the phospholipids can modulate exploratory behaviors and recognition memory in rodents.

High-throughput synthesis and optimization of ionizable lipids through A3 coupling for efficient mRNA delivery

BackgroundThe efficacy of mRNA-based vaccines and therapies relies on lipid nanoparticles (LNPs) as carriers to deliver mRNA into cells. The chemical structure of ionizable lipids (ILs) within LNPs is crucial in determining their delivery efficiency.ResultsIn this study, we synthesized 623 alkyne-bearing ionizable lipids using the A3 coupling reaction and assessed their effectiveness in mRNA delivery. ILs with specific structural features—18-carbon alkyl chains, a cis-double bond, and ethanolamine head groups—demonstrated superior mRNA delivery capabilities. Variations in saturation, double bond placement, and chain length correlated with decreased efficacy. Alkynes positioned adjacent to nitrogen atoms in ILs reduced the acid dissociation constant (pKa) of LNPs, thereby hindering mRNA delivery efficiency. Conversion of alkynes to alkanes significantly enhanced mRNA delivery of ILs both in vitro and in vivo. Moreover, combining optimized ILs with cKK-E12 yields synergistic LNPs that showed markedly augmented mRNA expression levels in vivo.ConclusionsOverall, our study provides insights into the structure–function relationships of ILs, providing a foundation for the rational design of ILs to enhance the efficacy of LNPs in mRNA delivery.Graphical

Hydrophobic Domain Modulation of Chemical Responsiveness in a Bolaamphiphile-Based Supramolecular Monomer.

Self-immolative chemistries that respond in an irreversible manner to external stimuli are highly attractive to permanently degrade filamentous supramolecular biomaterials. Within the monomer, a balance needs to be struck between its capacity to be supramolecularly polymerized and degraded at an appropriate rate for a given application. Herein, we unravel the structure-property-function relationships of a library of squaramide-based bolaamphiphiles bearing a central disulfide-based self-immolative spacer to construct supramolecular polymers responsive to chemical stimuli in aqueous solutions. We examine the impact of changing the alkyl domain length (2 to 12 methylene units) on the formation of supramolecular filaments and their rate of degradation in response to a biological antioxidant, glutathione. A minimum of an octyl spacer is required to robustly form supramolecular polymers that can be irreversibly degraded through a cyclization-elimination reaction of the self-immolative spacer triggered by thiol-disulfide exchange. Further increasing the peripheral alkyl chain length to a decyl spacer increases the ordered packing of the amphiphiles, hindering their chemical degradation. This study provides a framework to design chemically responsive filamentous supramolecular polymers based on bolaamphiphiles that can be irreversibly degraded in aqueous solutions for their eventual application as biomedical materials.

Combining in-situ quadrupole mass spectrometer analyses: Study on the structure–activity relationship and lubrication mechanisms of ammonium phosphate ionic liquids

Since the lubrication performances of ionic liquids are closely linked to their unique structures, four protic ionic liquids (PILs), [N44HH][DEHP], [N444H][DEHP], [N448H][DEHP] and [N4412H][DEHP], are designed to investigate the effect of cationic structures on the lubrication behaviors and lubrication mechanisms. Vacuum tribological tests were carried out to minimize the impact of the atmospheric environment. The structure–activity relationships and lubrication mechanisms of PILs were emphatically examined by in-situ quadrupole mass spectrometer (Q-MS) and XPS analyses. Results demonstrated that all four PILs exhibited outstanding lubrication performance under a vacuum condition. Unusually, extended alkyl chain cationic structures resulted in a changed lubrication mechanism, leading to a slight decrease in performance. In-situ Q-MS analyses and XPS further revealed that the length of the alkyl chain in cations influenced the strength of intermolecular forces in PILs, leading to changes in their lubrication performance and mechanisms.

Electrochemical self-doping in intrinsically ionic, thermally activated delayed fluorescence materials enables high-performance light-emitting electrochemical cells

Intrinsically ionic, thermally activated delayed fluorescence (TADF) materials are promising active materials for solid-state light-emitting electrochemical cells (LECs), but the origin for their superior device performances has remained elusive and how to further boost their device performances toward real world applications has remained an open question. Here, three TADF materials containing the same TADF unit have been prepared, which include a neutral one (R), an ionic one with an imidazolium cation being anchored to the acceptor through an alkyl chain (E1), and an intrinsically ionic one with an imidazolium cation being directly anchored to the acceptor (E2). By comparison between R, E1 and E2, it is revealed that n-type electrochemical self-doping occurs in E2 upon electron-injection onto its acceptor in operating LECs, due to in-situ formed, closely bound [electron-imidazolium cation] pair, which significantly enhances the device performance. By enhancing the chemical stability of the material and centering the carrier recombination zone in the active layer, the green LECs afford peak brightness up to 1461cd/m−2, external quantum efficiencies (EQEs) up to 9.1 %, and half-lifetimes up to 371h at constant current of 50 A/m−2. Peak brightness/EQE/half-lifetime at 322 cd/m−2/10.1 %/∼1800 h has further been achieved at constant current of 10 A/m−2. These LECs represent the most efficient, bright, and stable TADF LECs reported so far. The work clarifies the great advantage and huge potential of intrinsically ionic TADF materials, with unique electrochemical self-doping capacity, for fabricating efficient, bright and stable light-emitting devices.