Alkyl Chain Length Research Articles

A scalable and universal strategy for constructing long-term antibacterial coatings with lubricant property on medical catheters

Medical catheters might cause a high morbidity of catheter-associated urinary tract infections (CAUTIs) because of the bacterial adhesion onto the surface. In addition, the inherent hydrophobicity of catheter materials exacerbates mechanical friction, leading to tissue damage. Therefore, coatings with integrated antibacterial and lubricative properties are appealing approaches to mitigate these challenges. In this study, a kind of polyurethane (PU)-based coatings were developed and prepared on medical catheters, which were modified with a cationic antibacterial agent, quaternized ammonium-modified methyldiethanolamines (QMDEAs). Due to the reaction among castor oil tertiary alcohols, isocyanates and QMDEAs, a polymer cross-linked network was fabricated, in which a hydrophilic polymer, polyvinylpyrrolidone (PVP), was added to form a semi-interpenetrating network. The structures of the coatings were regulated by adjusting the lengths of alkyl chain of QMDEAs, concentrations of pre-coated solutions, ratios of QMDEA:isocyanate, and parameters of preparation process. Among the coatings we prepared, PU-C10–46 possessed the optimized performances, which reduced the dynamic friction coefficient by 91.38 % and had the antibacterial efficiency of 99.9 % with good biocompatibility. The in vivo anti-infective properties of PU-C10–46 were also demonstrated by an infected animal model. Furthermore, PU-C10–46 was produced in an industrial equipment, and the large-scaled industrial products also had the same performances. This work could provide a promising strategy to deal with the challenges of medical catheter-associated infection.

Study of mesomorphic, thermal and optical properties of 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6) supramolecular hydrogen bonded mesogenic complexes

Within the scope of this study, the process of producing and analyzing a liquid crystalline substance (supramolecular hydrogen-bonded mesogen) is presented. The formation of this mesogen involves the use of two chemicals, namely 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6). Equimolar (1:1) 5BA/5CB and 5BA/6CB binary combination samples have been organized by using one at a time mixing 5CB and 6CB liquid crystal chemical substances with 5BA. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) are employed for the examination of phase transitions, and liquid crystalline phase texture properties of the produced mesogens. The phase transformation sequence that occurred during heating and cooling is Crystal (Cr) ↔ Smectic A (SmA) ↔ Nematic (N) ↔ Isotropic (I) with the 1st order or weakly 1st order transition. The nematic range value observed for 5BA/6CB is considerably smaller than the nematic range value observed for 5BA/5CB, but the thermal mesophase range value for both is approximately the same. Fourier-transform infrared (FTIR) evaluation of 5BA, 5CB, and their hydrogen-bonded combos (5BA/nCB; n = 5, 6) confirmed attribute peaks. The X-ray diffraction (XRD) study revealed that the produced mesogens possess a crystalline structure. In addition, UV–Vis experiments demonstrated that the increase in alkyl chain length in the combination resulted in a decrease in absorbance and wavelength values, while leading to an increase in absorbency and band gap energy values. These results propose workable purposes for the synthesized substances in liquid crystal displays and other optoelectronic devices. Overall, the findings display the feasibility and viability of these novel hydrogen-bonded liquid crystalline mesogens in various technological applications.

Interfacial Rheological Investigation of Modified Silica Nanoparticles with Different Alkyl Chain Lengths at the n-Octane/Water Interface.

The interfacial dilational rheology of silica nanoparticles (NPs) directly reflects the relationship between surface structure and interfacial behaviors in NPs, which has attracted significant attention in various industrial fields. In this work, modified silica nanoparticles (MNPs) with various alkyl chain lengths were synthesized and systematically characterized using Fourier transform infrared spectra, Zeta potential, and water contact angle measurements. It was found that the MNPs were successfully fabricated with similar degrees of modification. Subsequently, the interfacial behaviors of the MNPs in an n-octane/water system were investigated through interfacial dilational rheological experiments. The length of the modified alkyl chain dominated the hydrophilic-lipophile balance and the interfacial activity of the MNPs, evaluated by the equilibrium interfacial tension (IFT) variation and dilational elasticity modulus. In the large amplitude compression experiment, the balance between the electrostatic repulsion and interfacial activity in the MNPs was responsible for their ordered interfacial arrangement. The MNPs with the hexyl alkyl chain (M6C) presented the optimal amphipathy and could partly overcome the repulsion, causing a dramatic change in surface pressure. This was further confirmed by the variations in IFT and dilational elasticity during the compression path. The study provides novel insights into the interfacial rheology and interactions of functionally modified NPs.

Emergent Ferroelectric Nematic and Heliconical Ferroelectric Nematic States in an Achiral "Straight" Polar Rod Mesogen.

Ferroelectric nematic liquid crystals (NFLCs) are distinguished by their remarkable polarization characteristics and diverse physical phenomena, sparking significant interest and excitement within the scientific community. To date, over 150 NFLC molecules are developed; however, there are no reports regarding straight linear polar molecules with a parallel alignment of the permanent dipole moment and the molecular axis. The straight polar mesogen nBOE exhibits an enantiotropic NF phase with a wide temperature window (up to 100 K) despite having a longer alkyl chain (up to n = 6) than the critical alkyl chain length of conventional models. Interestingly, nBOE with a medium-length alkyl chain displays an exotic phase sequence of NF-HCNF-SmXF during the elimination of positional displacement among adjacent molecules. Furthermore, the reflective color modulation of the HCNFLC over the entire VIS-NIR spectral regime by ultralow E-field (up to 0.14V µm-1) is demonstrated.

Identification of Δ8-Tetrahydrocannabinol (THC) and Δ9-THC Analogs, with Different Lengths of Alkyl Chain at C-3 Position, in Oil Products Distributed on the Internet

Since around 2021, products claiming to contain a Δ9-tetrahydrocannabinol (THC) analog with different lengths of alkyl chain at C-3 position have been sold on the internet in Japan. Δ9-THC has a pentyl group derived from the precursor olivetol at the C-3 position. These products include liquid cartridges for electronic cigarettes, herbal products, and gummy products. This study analyzed and determined the ingredients in five oil products distributed on the internet from 2022 to 2023 that claim to contain THC analogs. Samples of each product were used for GC-MS and LC-MS measurements. After isolating and purifying the unknown components from the products, structural analysis was performed by measuring 1H, 13C-NMR and various two-dimensional NMR [HH correlation spectroscopy (H-H COSY), heteronuclear multiple quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC), and nuclear Overhauser effect spectroscopy (NOESY)]. The analysis identified Δ8-tetrahydrocannabivarin (THCV), Δ9-THCV, Δ8-tetrahydrocannabutol (THCB), Δ9-THCB, Δ8-tetrahydrocannabihexol (THCH), Δ9-THCH, Δ8-3-octyl-THC (THCjd) and Δ9-THCjd. These compounds were Δ8-THC or Δ9-THC analogs with different lengths of alkyl chain at C-3 position. Meanwhile, Δ4(8)-iso-THCV and Δ11-THCB were identified as minor components of the product, and were considered to be the reaction byproducts of the synthesis of the Δ8-THC or Δ9-THC analogs. In the future, there are concerns about the distribution of products containing new THC analogs. Therefore, continuous provision monitoring of newly detected in the products is important.

Influence of the alkyl chain-length on the luminescent properties of 6‑hydroxy-2-naphthoate moieties: Preparation, crystal structure and Hirshfeld surface analysis

To further explore the luminescent materials, a set of 6‑hydroxyl-naphthoate derivatives have been obtained through the esterification reaction of 6‑hydroxy-2-naphthoic acid with a series of organic alcohols (methanol, ethanol, n-propanol and n-butanol, respectively) in the presence of phenyl sulfonic acid. The title compounds were characterized by FT-IR, elemental analysis (EA), UV–vis spectra, NMR and single-crystal X-ray diffraction. Compounds 1–5 are 6‑hydroxy-2-naphthoic acid, methyl 6‑hydroxy-2-naphthoate, ethyl 6‑hydroxy-2-naphthooate, n-propyl 6‑hydroxy-2-naphthoate and n‑butyl 6‑hydroxy-2-naphthoate, respectively. Compounds 1–5 crystallizes in the space group P21/c, Pna21, P21/n, P21/c and P-1, respectively. The C/OH···O hydrogen bonds can be observed. The luminescent emission maxima of compounds 1–5 can be found at 386, 393, 405, 407 and 420 nm in the solid state, respectively, indicating that the photoluminescent peaks occur the bathochromic-shift with the growth of the alkyl chain-lengths. Additionally, there exists the same order for the quantum yields. Meanwhile, the Hirshfeld surface analysis proves that the H···H interactions can be responsible for the emission maxima of these target compounds. The trend of the melting point decreases with the reduction of O···H interactions, and with the increment of the alkyl chain-lengths. The repulsion energy of the target compounds also shows the same tendency, which can be confirmed by the energy framework analysis.

Ligand Tail Controls the Conformation of Indium Sulfide Ultrathin Nanoribbons.

We report the conformational control of 2D ultrathin indium sulfide nanoribbons by tuning their amine ligands' alkyl chain. The initial orthorhombic InS nanoribbons bare n-octylamine ligands and display a highly curved geometry with a characteristic figure of eight shapes. Exchanging the native ligand by oleylamine induces their complete unfolding to yield flat board-shaped nanoribbons. Significant strain variations in the InS crystal structure accompany this shape-shifting. By tuning the linear alkyl chain length from 4 to 18 carbon atoms, we show using small-angle X-ray scattering in solution and transmission electron microscopy that the curvature of the nanoribbon subtly depends on the ligand-ligand interactions at the nanoribbon's surface. The curvature decreases gradually as the chain length increases, while carbon unsaturation has an unexpectedly significant effect at constant chain length. These experiments shed light on the critical role of the ligand monolayer on the curvature of ultrathin 2D crystalline nanosheets and demonstrate that weak supramolecular forces within the organic part of colloidal nanocrystals can dramatically impact their shape. This transduction mechanism, in which changes in the organic monolayer impact the shape of a nanocrystal, will help to devise new strategies to design stimuli-responsive systems that take advantage of both the flexibility of organic moieties and the physical properties of the inorganic core.

Enhancing Light Utilization Efficiency of Semi‐Transparent Perovskite Solar Cells via Tailored Interfacial Engineering

AbstractSemi‐transparent perovskite solar cells (ST‐PSCs) are promising for their application in building integrated photovoltaics (BIPVs). For BIPVs, a light utilization efficiency (LUE) > 2.5 is required which is multiplication of average visible transmittance (AVT) and power conversion efficiency (PCE). Generally, semitransparency is achieved by reducing film thickness which increases AVT but decreases PCE resulting in lower LUE. Here, an interface engineering strategy is employed on a wide bandgap perovskite thin absorber layer to increase PCE and LUE. The study employs three different alkylamine hydrochlorides molecules with varied alkyl chain length, viz., 2‐chloroethylamine‐hydrochloride, 3‐chloropropylamine‐hydrochloride, and 4‐chlorobutyalamine‐hydrochloride at perovskite/electron transport layer (ETL) interface and investigates their effect on perovskite crystallization. Further, it is demonstrated that 4‐chlorobutyalamine‐hydrochloride can strongly interact with perovskite and suppress non‐radiative recombination facilitating charge transport at the perovskite/ETL interface. Devices post‐treated with 4‐chlorobutyalamine‐hydrochloride interfacial layer, demonstrate a higher LUE of 3.45% (PCE 14.11%) and AVT of ≈25% (400–800 nm), with Voc of 1.23 V. Moreover, the unencapsulated devices retain ≈89% of the initial efficiency after storage for 1500 h under a relative humidity of ≈35–40%. This study provides an efficient approach to improve LUE and stability of ST‐PSCs for the application in energy‐efficient smart windows.

Biodegradable and biocompatible nonisocyanate polyurethanes synthesized from bio-derived precursors

Despite the enormous use of polyurethanes (PUs) in multiple aspects of modern lifestyle, the industrial scale manufacturing of PUs uses toxic chemicals like isocyanates, phosgene till today. In addition, the non-biodegradability and non-biocompatibility of PUs and their debris are serious cause of concerns for the environment. To deal with these challenges, in the current work, a new approach is reported in which bio-derived non-isocyanate polyurethanes were synthesized by exploiting viable amino acid-based diamines and biscyclocarbonates from sebacoyl chloride and diglycerol derivatives in a readily doable process. The newly designed polyhydroxyurethanes (PHUs) exhibited remarkable biodegradability and biocompatibility (cell viability) in comparison with commercial diamine based PHUs. A series of PHUs were synthesized in bulk and solvent free green synthetic route by polycondensing library of amino acids (such as glycine, alanine, valine, and isoleucine etc.) based diamines consisting of varying alkyl chain lengths and biscyclocarbonates like sebacic biscyclocarbonate and diglycerol biscyclocarbonate etc. All the synthesized PHUs were thoroughly characterised by IR, NMR and HRMS spectroscopic techniques. The impact of chain length and molecular structure of the synthesized PHUs were also evaluated using DSC, TGA, SEC, water contact angle measurements and hydrolytic degradation studies. The molar masses of the PHUs obtained from the SEC analysis are in the range of ∼17,000–24,000 Da. The current study demonstrated that amino acids is one of the major degradation products and are biocompatible in in-vitro conditions. The PHUs and their degradable products showed excellent cell viability when studied in HEK293T cells that were carried out using microgram to milligram concentration of PHUs. The outcome of this work in comparison to conventional PHUs and polyurethanes clearly demonstrated good biocompatibility and hence drawing attention to potential applications in bio-adhesives, bio-implants, drug delivery, and green coatings etc. in the near future.

Developing a Passive Dosing Method for Acute Aquatic Toxicity Tests of Cationic Surfactant Benzalkoniums (BACs).

Benzalkonium chlorides (BACs) have been of environmental concern due to their widespread use and potential harm. However, challenges arise in defining and controlling the exposure concentration (Cw) in aquatic toxicity tests involving BACs with a long alkyl chain (i.e., #C > 14). To address this, a novel passive dosing method was introduced in the 48 h-acute ecotoxicity test on Daphnia magna and compared to the conventional solvent-spiking method in terms of Cw stability and toxicity results. Among 13 sorbent materials tested for their sorption capacity, poly(ether sulfone) (PES) membrane was an optimal passive dosing reservoir, with equilibrium desorption of BACs to water achieved within 24 h. The Cw of BACs remained constant in both applied dosing methods during the test period. However, the Cw in solvent-spiking tests was lower than the nominal concentration for long-chain BACs, particularly at low exposure concentrations. Notably, the solvent-spiking tests indicated that the toxicity of BACs increased with alkyl chain length from C6 to 14, followed by a decline in toxicity from C14 to 18. In contrast, the passive dosing method displayed similar or slightly increasing toxicity levels of BACs from C14 to C18, indicating higher toxicity of C16 and C18-BACs than that inferred by the solvent spiking test. These findings emphasize the potential of applying this innovative passive dosing approach in aquatic toxicity tests to generate reliable and accurate toxicity data and support a comprehensive risk assessment of cationic surfactants.

Experimental and Theoretical Studies on Long Alkyl Chain-Bearing Dibenzotriazole Ionic Liquids as Eco-friendly Corrosion Inhibitors in Aqueous Hydrochloride Acid.

Three long alkyl chain-bearing dibenzotriazole ionic liquids (BTA-R-BTA, R = 8, 12, and 16) were synthesized with high yield (>98%) through a simple and eco-friendly process. Their anticorrosion performance for Q235 carbon steel in 6 M hydrochloride acid was comprehensively evaluated by weight loss tests, electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy), and surface analysis techniques. As the length of the alkyl chain increased, the maximum corrosion inhibition efficiency enhanced from 55.02% (for BTA-8-BTA at 1.2 mM) to 97.10% (for BTA-12-BTA at 0.3 mM) and 98.84% (for BTA-16-BTA at 0.3 mM). Density functional theory calculation indicated that the alkyl chain length had little influence on the inhibitors' electronic structures, while molecular dynamics simulations revealed that the thickness, surface coverage, and compactness of adsorption films formed at the metal-electrolyte interface increased with the elongated alkyl chain. Corrosion inhibition efficiency is strongly correlated with the structures of the adsorption film.

Isoreticular Covalent Organic Pillars: Engineered Nanotubular Hosts for Tailored Molecular Recognition.

In the realm of nanoscale materials design, achieving precise control over the dimensions of nanotubular architectures poses a substantial challenge. In our ongoing pursuit, we have successfully engineered a novel class of single-molecule nanotubes─isoreticular covalent organic pillars (iCOPs)─by stacking formylated macrocycles through multiple dynamic covalent imine bonds, guided by principles of reticular chemistry. Our strategic selection of rigid diamine linkers has facilitated the synthesis of a diverse array of iCOPs, each retaining a homologous structure yet offering distinct cavity shapes influenced by the linker choice. Notably, three of these iCOP variants feature continuous one-dimensional channels, exhibiting length-dependent host-guest interactions with α,ω-dibromoalkanes, and each presenting a distinct critical guest alkyl chain length threshold for efficient guest encapsulation. This newfound capability not only provides a platform for tailoring nanotubular structures with precision, but also opens new avenues for innovative applications in molecular recognition and the purification of complex mixtures.

Comprehensive evaluation of physical properties and carbon dioxide capacities of new 2-(butylamino)ethanol-based deep eutectic solvents

Abstract The aim of this research was to assess the impact of the components of alkanolamine deep eutectic solvents (DESs) on the physical properties of those DESs and their carbon dioxide capacity. To achieve this goal, novel deep eutectic solvents were synthesized by using 2-(butylamino)ethanol (BAE) as the hydrogen bond donor (HBD), along with tetrabutylammonium bromide TBAB), tetrabutylammonium chloride (TBAC), or tetraethylammonium chloride (TEAC) as the hydrogen bond acceptors (HBA) at various molar ratios (1:6, 1:8, and 1:10). To confirm the presence of hydrogen bond interactions between the components Fourier Transform Infrared Spectroscopy measurements were conducted. Furthermore, thermal properties, including melting points and thermal stability, of these deep eutectic solvents as well as key physical properties, such as density, viscosity, refractive index, and sound velocity, within the temperature range of 293.15–333.15 K and at a pressure of 0.1 MPa were examined. The effect of the molar ratio of HBA to HBD, the type of anion, and the length of the alkyl chain were studied and analysed in regard to physicochemical properties. In this work, the solubility of carbon dioxide in DESs derived from 2-(butylamino)ethanol, 3-aminopropan-1-ol (AP), and 2-(methylamino)ethanol (MAE) was measured. The highest CO2 capacity was found for TEAC:MAE 1:10 DES characterized by the shortest alkyl chain length in both HBA and HBD molecules, the highest amine content, and the lowest viscosity. Additionally, the effect of water addition on carbon dioxide solubility was explored. The results showed that the influence of water on CO2 solubility varies with the type of DES. In general, this work highlighted that DESs can serve as effective media for carbon dioxide capture, and their performance can be tailored by changing the type of hydrogen bond acceptor or donor, their molar ratio and by the addition of water.

Shifting Mycobacterial Serine Hydrolase Activity Visualized Using Multi-Layer In-Gel Activity Assays.

The ability of Mycobacterium tuberculosis to derive lipids from the host, store them intracellularly, and then break them down into energy requires a battery of serine hydrolases. Serine hydrolases are a large, diverse enzyme family with functional roles in dormant, active, and reactivating mycobacterial cultures. To rapidly measure substrate-dependent shifts in mycobacterial serine hydrolase activity, we combined a robust mycobacterial growth system of nitrogen limitation and variable carbon availability with nimble in-gel fluorogenic enzyme measurements. Using this methodology, we rapidly analyzed a range of ester substrates, identified multiple hydrolases concurrently, observed functional enzyme shifts, and measured global substrate preferences. Within every growth condition, mycobacterial hydrolases displayed the full, dynamic range of upregulated, downregulated, and constitutively active hydrolases independent of the ester substrate. Increasing the alkyl chain length of the ester substrate also allowed visualization of distinct hydrolase activity likely corresponding with lipases most responsible for lipid breakdown. The most robust expression of hydrolase activity was observed under the highest stress growth conditions, reflecting the induction of multiple metabolic pathways scavenging for energy to survive under this high stress. The unique hydrolases present under these high-stress conditions could represent novel drug targets for combination treatment with current front-line therapeutics. Combining diverse fluorogenic esters with in-gel activity measurements provides a rapid, customizable, and sensitive detection method for mycobacterial serine hydrolase activity.

Dispersion-Driven Cooperativity in Alkyl Perylene Diimide Oligomers: Insights from Density Functional Theory.

The cooperative mechanism is of paramount importance in the synthesis of supramolecular polymers with desired characteristics, including molecular mass, polydispersity, and morphology. It is primarily driven by the presence of intermolecular interactions, which encompass strong hydrogen bonding, metal-ligand interactions, and dipole-dipole interactions. In this study, we utilize density functional theory and energy decomposition analysis to investigate the cooperative behavior of perylene diimide (PDI) oligomers with alkyl chains at their imide positions, which lack the previously mentioned interactions. Our systematic examination reveals that dispersion interactions originating from the alkyl side-chain substituents play an important role in promoting cooperativity within these PDIs. This influence becomes even more pronounced for alkyl chain lengths beyond hexyl groups. The energy decomposition analysis reveals that the delicate balance between dispersion energy and Pauli repulsion energy is the key driver of cooperative behavior in PDIs. Additionally, we have developed a mathematical model capable of predicting the saturated binding energies for PDI oligomers of varying sizes and alkyl chain lengths. Overall, our findings emphasize the previously undervalued significance of dispersion forces in cooperative supramolecular polymerization, enhancing our overall understanding of the cooperative mechanism.

Methylimidazolium ionic liquids - A new class of forever chemicals with endocrine disrupting potential

A class of chemical with a potentially important perceived future contribution to the net zero carbon goal (as “green” solvents) is the methylimidazolium ionic liquids (MILs). These solvents are used in industrial processes such as biofuel production yet little is known about their environmental stability or toxicity in man although one MIL – 1-octyl-3-methylimidazolium (M8OI) – has been shown to activate the human estrogen receptor alpha (ERα). The stabilities of the chloride unsubstituted methylimidazolium (MI) and MILs possessing increasing alkyl chain lengths (2C, 1-ethyl-3-methylimidazolium (EMI); 4C, 1-butyl-3-methylimidazolium (BMI); 6C; 1-hexyl-3-methylimidazolium (HMI), 8C, M8OI; 10C, 1-decyl-3-methylimidazolium (DMI)) were examined in river water and a human liver model system. The MILs were also screened for their abilities to activate the human ERα in vitro and induce uterine growth in pre-pubertal rats in vivo. Short chain MILs (EMI, BMI and HMI) underwent negligible metabolism and mineralisation in river water; were not metabolised in a model of human liver metabolism; activated the human ERα in vitro and were estrogenic in vivo in rats. A structure-based computational approach predicted short chain MIL binding to both the estrogen binding site and an additional site on the human estrogen receptor alpha. Longer chain MILs (M8OI and DMI) were metabolised in river water and partially mineralised. Based on structure-activity considerations, some of these environmentally-derived metabolites may however, remain a hazard to the population. MILs therefore have the potential to become forever chemicals with adverse effects to both man, other animals and the environment in general.

Molecular Insights into the Conformational and Binding Behaviors of Human Serum Albumin Induced by Surface-Active Ionic Liquids.

Extensive research has been carried out to investigate the stability and function of human serum albumin (HSA) when exposed to surface-active ionic liquids (SAILs) with different head groups (imidazolium, morpholinium, and pyridinium) and alkyl chain lengths (ranging from decyl to tetradecyl). Analysis of the protein fluorescence spectra indicates noticeable changes in the secondary structure of HSA with varying concentrations of all SAILs tested. Helicity calculations based on the Fourier transform infrared (FTIR) data show that HSA becomes more organized at the micellar concentration of SAILs, leading to an increased protein activity at this level. Small-angle neutron scattering (SANS) data confirm the formation of a bead-necklace structure between the SAILs and HSA. Atomistic molecular dynamics (MD) simulation results identify several hotspots on the protein surface for interaction with SAIL, which results in the modulation of protein conformational fluctuation and stability. Furthermore, fluorescence resonance energy transfer (FRET) experiments with the intramolecular charge transfer (ICT) probe trans-ethyl p-(dimethylamino) cinnamate (EDAC) demonstrate that higher alkyl chain lengths and SAIL concentrations result in a significantly increased energy transfer efficiency. The findings of this study provide a detailed molecular-level understanding of how the protein structure and function are affected by the presence of SAILs, with potential implications for a wide range of applications involving protein-SAIL composite systems.

Fabrication of ionic liquid self-assemblies based on dicamba with improved herbicidal activity and reduced environmental risks

The off-target loss of pesticide formulations caused by volatilization and leaching has reduced effective utilization and increased risks to the ecological environment and human health. Self-assembly of pesticides has been widely concerned due to the improved bioactivity and environmental compatibility. Herbicidal ionic liquids (HILs) could effectively decrease off-target loss and increase efficacy and environmental safety by improving the physicochemical properties of herbicides. Herein, HILs were prepared by pairing dicamba with quaternary ammonium salts containing different alkyl chain lengths and aromatic groups and subsequently self-assembled into spherical nanoparticles (HIL NPs) via electrostatic interaction and hydrophobic effect. Compared with dicamba, the obtained HIL NPs with an average particle size of 6–55 nm exhibited improved physicochemical properties, including high zeta potential values (+20.3 to +27.8 mV), low volatilization rate (2.4–3.9 %) and surface tension (22.83–33.07 mN m−1), decreased contact angle (32.25–41.55°) and leaching potential (76.2–86.5 %), and high soil adsorption (12.1–23.8 %), suggesting low risks to the environment. The control efficacy against Amaranthus retroflexus of HIL3 NPs pairing dicamba with octadecyl-trimethyl ammonium chloride was better than that of dicamba sodium salt at different concentrations. Therefore, the ionic liquid self-assembly developed by a facile and green preparation approach to reduce the volatility and leaching of pesticides would have enormous potential in sustainable agriculture.

Anion Effect on the Excited-State Intramolecular Proton Transfer of 4'-N,N-Diethylamino-3-hydroxyflavone in Ionic Liquids.

The excited-state intramolecular proton transfer (ESIPT) reaction of 4'-N,N,-diethylamino-3-hydroxyflavone (C2HF) was studied using time-resolved fluorescence measurements in ionic liquids (ILs) of various anions with a fixed cation (1-ethyl-3-methylimidazolium [C2mim]+). C2HF showed an ESIPT reaction from the normal excited state (N*; keto form) to the tautomer excited state (T*; enol form) where both states are emissive. The ESIPT rate and yield were obtained by analyzing the time-resolved fluorescence spectra measured using the optical Kerr gate method. Both the ESIPT rate and yield decreased with increasing hydrogen-bond accepting ability of the anion. According to density functional theory calculations, the complex formation energy between C2HF and the anion became significantly negative with increasing the hydrogen-bond accepting ability of anion. The pseudoequilibrium constant between N* and T* ([T*]/[N*]) in the electronic excited state decreased with increasing hydrogen-bond accepting ability of the anion, while it increased with increasing the alkyl-chain length of alkyl sulfonate. The excitation wavelength dependence of the ESIPT rate and yield was studied for C2HF in [C2mim][C6H13SO3]. The ESIPT yield decreased by nearly a factor of 2 with increasing excitation wavelength from 360 to 425 nm, although the change in the ESIPT rate was small. The solvation heterogeneity due to the alkyl chain in the anion was considered to be the reason for the excitation wavelength dependence.

The relationship between the structure of stearic acid diamide lubricants and the lubrication properties in acrylonitrile-butadiene-styrene resins

Although amide lubricants are commonly used as lubricants for acrylonitrile-butadiene-styrene (ABS) resins, the relationship between their structure and lubricating properties remains unclear. In this paper, a series of stearic acid diamide lubricants for ABS resins were synthesized through an amidation reaction with the stearic acid and aliphatic diamines. The chemical structure was characterized by FTIR and 1H NMR. A detailed evaluation of the lubrication effect of the lubricant was carried out by dynamic mechanical analysis, rotational rheometry, contact angle measurements, and so on. The results showed that the complex viscosity, glass transition temperature and diamine's alkyl chain length of stearic acid diamides were positively correlated, while the elongation at break displayed a negative correlation. Compared to ethylenediamine bis stearate acid (EBA), 1,8-diaminooctane bis stearate acid (OBA) exhibited a 37.8 % increase in the complex viscosity at 0.1 rad/s, along with a 4.6 % rise in the glass transition temperature. It was indicated that the lubrication effect of stearic acid diamides deteriorated with the increase of the alkyl chain lengths of diamines. The lubrication mechanism was further validated by molecular dynamics simulations. As the alkyl chain lengths of diamines increased, the mean square displacement and interaction energy of the system exhibited a tendency to become lower and higher, respectively. This meant that the longer alkyl chains of the diamines in the lubricants were not advantageous to the free mobility of the matrix molecular chains. These findings provided insightful guidance for the sensible design of lubricants for ABS resins.