Alkyl Chain Length Research Articles

Bioactive Ion‐Confined Ultracapacitive Memristors with Neuromorphic Functions

The field of bioinspired iontronics, bridging electronic devices and ionic systems, has multiple biological applications. Carbon‐based ultracapacitive devices hold promise for controlling bioactive ions via electric double layers due to their high‐surface‐area and biocompatible porous carbon electrodes. However, the interplay between complex bioactive ions and porous carbons remains unclear due to the variety of structures of bioactive ions present in biological systems. Herein, we investigate the adsorption behavior of a series of bioactive ammonium‐based cations with varying alkyl chain lengths in nanoporous carbons. We find that strong physisorption results from the synergistic hydrophobic interaction and electrostatic attraction between porous carbons (with a negative zeta potential) and bioactive cations. Bioactive cations with varying alkyl chain lengths can be irreversibly physically adsorbed and confined within nanoporous carbons resulting in anion enrichment and depletion during electric polarization. This situation, in turn, results in a characteristic memristive behavior in all‐carbon capacitive ionic memristor devices. Our findings highlight the relationship between the resistance state of the memristor and ion adsorption mechanisms in all‐carbon capacitive devices, which hold potential for future transmitter delivery, biointerfacing, and neuromorphic devices.

High-throughput screening of green amino acid and surfactant mixtures with high corrosion inhibition efficiency: Experimental and modelling perspectives

A high-throughput screening method is developed for rapid evaluation of corrosion inhibitors. By employing a fluorometric technique, this method quickly assesses the concentration of iron ions converted from corrosion products in the reaction pool to rapidly evaluate the corrosion inhibition performance of amino acid and surfactants. Utilizing this high-throughput screening platform, the corrosion inhibition effects of L-cysteine mixed with quaternary ammonium salts of different alkyl chain length were evaluated, and their optimal mixing ratios were determined. Through corrosion experiments and molecular simulations, the synergistic mechanisms of the inhibitor mixtures are revealed.

Surface engineered novel cationic surfactants with enhanced surface adsorption for environmental applications

Gemini Cationic Surfactants (GCS) have garnered significant attention due to their distinctive molecular structure, featuring two hydrophilic head groups associated with a hydrophobic spacer. This distinctive configuration enables diverse applications across various fields. Hence, the current study introduces a novel series of GCSs, ethanediyl-1,2-bis[di(2-hydroxypropyl) alkylammonium] dibromide (Cn-C2-Cn[IsoPr(OH)2; n = 9, 12 and 14) and comprehensively explore their properties, highlighting their promising antimicrobial activity. The synthesis of GCSs was validated using 1H NMR and IR spectroscopy. Dynamic Light Scattering was employed to determine the dimensions of Gemini surfactant aggregates in aqueous solutions. Surface tension analysis determined critical concentrations of micelle (CMC), minimum surface area (Amin) and concentration of surface excess (Γmax). Physicochemical properties were assessed through conductivity and surface tension analyses in aqueous solutions. The CMC, Amin and Γmax values decrease as alkyl chain length extends. Surface tension data revealed strong adsorption of GCSs at interfaces. π values (mN/m) ranged from 36.7 (C14C2C14[Iso-Pr(OH)]2) to 45.3 (C9C2C9[Iso-Pr(OH)]2). Conductivity and surface tension measurements further characterized Gemini surfactants in aqueous environments at 298 K. The size of the micelle aggregates varied between C9C2C9[Iso-Pr(OH)]2 (1.2885 nm) and C14C2C14[Iso-Pr(OH)]2 (1.9210 nm), highlighting the impact of chain length on micelle size. Hence, the study highlights significant effect of the chain lengths on Gemini cationic surfactants’ self-assembly in dilute aqueous environments. Antimicrobial tests demonstrated significant activity of Cn-C2-Cn[IsoPr(OH)]2 GCSs at varying concentrations. Antimicrobial tests showed the significant antimicrobial potential of these GCS compounds, suggesting their potential and promising applications in medical, hygiene, environmental sanitation and advanced materials sectors.

Long-chain alkyl emulsifiers induced asphalt particle dispersion: Lipophilicity-enhancement effect

The structure of the lipophilic groups within the emulsifiers plays a pivotal role in uniformly dispersing the asphalt particles in the water regarding the storage and thermal stability of emulsified asphalt. This study combines laboratory experiments with molecular dynamics simulations, investigating the influence of alkyl chain length on emulsified asphalt dispersion and behavior at the oil/water interface. The results reveal that long-chain alkyl emulsifiers (C16TAC and C18TAC) present a lipophilicity-enhancement effect. This phenomenon increases the free volume fraction of emulsified asphalt, reducing viscosity and improving the compatibility of emulsion. This results in smaller asphalt particle sizes (D50 = 1.982μm) and more uniform dispersion. Vigorously lipophilic long-chain alkyl promotes emulsifier molecular migration towards the asphalt phase, thickening the oil/water interfacial layer and reducing interfacial tension and energy by more than 90 %. Notely, long-chain alkyl emulsifiers establish strong hydrogen bonds with water molecules, leading to water molecule aggregation into a hydration layer. Laboratory experimental results demonstrate that this lipophilicity-enhancement effect significantly improves the storage and thermal stability of emulsified asphalt. This research recommends long-chain alkyl emulsifiers in developing and designing energy-efficient pavement engineering regarding high-performance emulsified asphalt.

An electrochemical and theoretical approach towards the efficient microwave synthesis of imidazolium-based ionic liquids for unprecedented mild steel corrosion inhibition in 0.5 M H2SO4 solution

The inhibition potential of newly synthesized imidazolium-based ionic liquids (IL-1 and IL-2) on mild steel corrosion in a 0.5 M H2SO4 solution has been comprehensively investigated using gravimetric analysis, potentiodynamic polarization, and electrochemical impedance spectroscopy across various temperatures. Gravimetric analysis indicated that the adsorption of these inhibitors adhered to the Langmuir adsorption isotherm. Significantly, IL-2, featuring a longer alkyl chain, demonstrated superior inhibition efficiency (92.51 % at 303 K) compared to IL-1 (88.71 % at 303 K). Potentiodynamic polarization studies revealed a mixed-type inhibitory behavior, impacting both anodic and cathodic reactions. Surface morphological analyses via SEM and EDX confirmed the formation of a protective film on the mild steel surfaces, substantiating the corrosion inhibition capabilities of IL-1 and IL-2. The novelty of this research lies in the application of density functional theory (DFT) using the B3LYP method, which elucidated that the alkyl chain length at the N-3 position in imidazolium cation-based ionic liquids significantly enhances their inhibition potential. This mechanistic insight suggests that these ionic liquids effectively obstruct both anodic and cathodic sites, providing robust corrosion protection in a 0.5 M H2SO4 solution.

Construction of controlled hyper-crosslinked nanofibrous tubes for Cr(VI) removal: Response surface, kinetics, and isotherm

Porous organic polymers (POPs) exhibit significant potential for adsorbing toxic metal ions in wastewater. Developing POPs with controlled morphologies is a pivotal direction in this field. This study synthesized a series of novel hyper-crosslinked nanofibrous tubes designated HCNT-Cn (n = 4, 8, 12, 16) via Friedel-Crafts alkylation and quaternization reactions. These reactions were fine-tuned through a post-synthetic strategy involving varying alkyl chain lengths. These materials were characterized using FT-IR, SEM, N₂ adsorption-desorption isotherms, among others, and they were specifically evaluated for their ability to adsorb Cr(VI). Among the variants, HCNT-C₄ exhibited the highest specific surface area (495.26 m2 g−1), superior hydrophilicity (CA = 48.7°), and optimal adsorption performance. The adsorption kinetics of HCNT-C₄ conformed to a pseudo-second-order model, while its adsorption isotherm aligned with the Langmuir model. An investigation into the impact of Cr(VI) removal was conducted using three independent variables in a Central Composite Design (CCD) response surface model, revealing that under optimal conditions, the Cr(VI) removal efficiency reached 98%. Additionally, a mechanism for Cr(VI) adsorption on HCNT-C₄ was proposed. It was also found that HCNT-C₄ could be reused up to four times, maintaining a removal efficiency of 70%. This study suggests potential applications for removing Cr(VI) from contaminated wastewater.

Synthesis, Surface Activity, Emulsifiability and Bactericidal Performance of Zwitterionic Tetrameric Surfactants.

In this paper, a series of tetrameric surfactants (4CnSAZs, n = 12, 14, 16) endowed with zwitterionic characteristic were synthesized by a simple and convenient method and their structures were characterized by FT-IR, 1H NMR and elemental analysis. Their physicochemical properties were studied using the Wilhelmy plate method, fluorescence spectra and dynamic light scattering technique. 4CnSAZs have higher surface activities and tend to adsorb at the air/water surface rather than self-assembling in aqueous solution. The thermodynamic parameters obtained from surface tension measurements show that both processes of adsorption and micellization of 4CnSAZs are spontaneous and that the micellization processes of 4CnSAZs are entropy-driven processes. Both adsorption and micellization of 4CnSAZs are inclined to occur with the increase of alkyl chain length or temperature. For 4C12SAZs, there are only small-size aggregates (micelles), while the large aggregates (vesicles) are observed at the alkyl length of 4CnSAZs of 14 or 16. This shows that the alkyl chain length for oligomeric surfactants has a greater sensitivity for aggregate growth. The aggregate morphologies obtained from the calculated values of critical packing parameter (p) for 4C14SAZs and 4C16SAZs can be supported by the DLS measurement results. The test results obtained by the separation-water-time method show that 4CnSAZs have good emulsification performance and that the prepared emulsions appear to exit in the form of multiple emulsions. In addition, 4CnSAZs have good antibacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The present study reveals the unique behavior of a zwitterionic tetrameric surfactant and may give new insights into molecular design and synthesis of a high degree of surfactants with different structure characteristics for potential application in various industrial fields.

Effect of Alkyl Chain Length on Room-Temperature Phosphorescent Probes for Mitochondria-Targeted Imaging.

Room temperature phosphorescent (RTP) probes have significant advantages in the field of cellular imaging, as their long lifetimes can prevent interference from the spontaneous fluorescence of organisms. Persulfurated arenes are a typical RTP molecular parent nucleus. However, most of the applied research on them is concentrated in anti-counterfeiting, and relatively few are applied in bioimaging. The molecular structure and structure-property relationship of them applied in bioimaging are still in the exploration stage. In this work, we have designed and synthesized a series of RTP probes with long alkyl chains, all of which can be targeted to mitochondria with good water solubility for mitochondria-targeted imaging. Further, we investigated the effect of alkyl chains on the luminescence properties of these probes, and found that the moderate length of alkyl chains can realize the enhancement of phosphorescence intensity. We believe this finding is of guiding significance for the design of molecular structures in the field of RTP probes.

Effect of the alkyl chain length of α,ω-dichloroalkane on the Gibbs energy of transfer for functional groups.

Ion-transfer reactions of alkyl and perfluoroalkyl carboxylate ions (CH3(CH2)n-2COO- with n = 8-12 and CF3(CF2)n-2COO- with n = 3-9) were investigated at the polarized Cl-(CH2)m-Cl with m = 2, 4, 6, and 8 (O) | water (W) interface to evaluate the effects of n and m on the solvation energy of the ions, as well as on their methylene and terminal groups. These ions exhibited reversible or quasi-reversible voltammetric waves due to their transfer across the O | W interfaces, enabling the determination of formal potentials and formal Gibbs transfer energies from O to W, . The values for CH3(CH2)n-2COO- and CF3(CF2)n-2COO- increased linearly with n, allowing the estimation of for methylene and difluoromethylene groups, (CH2) and (CF2), and for their terminal groups, (COO- + CH3) and (COO- + CF3). Whereas the (CH2) and (CF2) hardly changed with the variation in m, the (COO- + CH3) and (COO- + CF3) decreased noticeably. These results suggest that the solvation energy for ions in Cl-(CH2)m-Cl increases with m, regardless of hydrophilic or lipophilic nature of the ions. Based on these findings, the advantage of using Cl-(CH2)m-Cl with a large m as a non-aqueous solvent for ion-transfer voltammetry was discussed.

Synthesis and Antibacterial Properties of Novel Quaternary Ammonium Lignins.

The ongoing demand for effective antimicrobial materials persists, and lignin emerges as a promising natural antibacterial material with renewable properties. The adaptability of lignin to various chemical modifications offers avenues to enhance its antimicrobial activity. Here, we employed chloromethylation and subsequent functionalization with variable tertiary N-alkyl dimethyl amines to produce C6-C18 quaternary ammonium lignins (QALs) from hardwood (aspen), softwood (pine), and grass (barley straw). Successful synthesis of QALs was confirmed through NMR and FTIR analysis results along with an increase in the surface ζ-potential. Antibacterial activity of QALs against clinical strains of Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus was assessed using minimal bactericidal concentration (MBC) assay and agar growth inhibition zone (ZOI) test. The antibacterial activity of QALs was found to be higher than that of the unmodified lignins. QALs with longer alkyl chains demonstrated an MBC of 0.012 mg/L against K. pneumoniae already after 1 h of exposure with similar effect size reached after 24 h for S. aureus. For all the lignins, an increase in alkyl chain length resulted in an increase in their bactericidal activity. MBC values of C14-C18 QALs were consistently lower than the MBC values of QALs with shorter alkyl chains. Besides the alkyl chain length, MBC values of barley and pine QALs were negatively correlated with the surface ζ-potential. While alkyl chain length was one of the key properties affecting the MBC values in a liquid-based test, the agar-based ZOI test demonstrated an antibacterial optimum of QALs at C12-C14, likely due to limited diffusion of QALs with longer alkyl chains in a semisolid medium.

Alkyl chain length-regulated in situ intelligent nano-assemblies with AIE-active photosensitizers for photodynamic cancer therapy

Photodynamic therapy (PDT) brings new hope for the treatment of breast cancer due to few side effects and highly effective cell killing; however, the low bioavailability of traditional photosensitizers and their dependence on oxygen severely limits their application. Aggregation-induced emission (AIE) photosensitizers (PSs) can dramatically facilitate the photosensitization effect, which can have positive impacts on tumor PDT. To-date, most AIE photosensitizers lack tumor targeting capability and possess poor cell delivery, resulting in their use in large quantities that are harmful to healthy tissues. In this study, a series of AIE photosensitizers based on pyridinium-substituted triphenylamine salts (abbreviated to TTPAs 1–6) with different alkyl chain lengths are synthesized. Results reveal that TTPAs 1–6 promote the generation of type I and type II reactive oxygen species (ROS), including ·OH and 1O2. In particular, the membrane permeability and targeting of TTPAs 4-6 bearing C8-C10 side-chains are higher than TTPAs 1-3 bearing shorter alkyl chains. Additionally, they can assemble with albumin, thereby forming nanoparticles (TTPA 4–6 NPs) in situ in blood, which significantly facilitates mitochondrial-targeting and strong ROS generation ability. Moreover, the TTPA 4–6 nanoparticles are pH-responsive, allowing for increased accumulation or endocytosis of the tumor and enhancing the imaging or therapeutic effect. Therefore, the in vivo distributions of TTPA 4–6 nanoparticles are visually enriched in tumor sites and exhibited excellent photodynamic cancer therapy efficacy. This work demonstrates a novel strategy for AIE PDT and has the potential to play an essential role in clinical applications using nano-delivery systems.

Whole-cell biocatalysis for phthalate esters biodegradation in wastewater by a saline soil bacteria SSB-consortium

Phthalic acid esters (PAE) are widely used as plasticizers and have been classified as ubiquitous environmental contaminants of primary concern. PAE have accumulated intensively in surface water, groundwater, and wastewaters; thus, PAE degradation is essential. In the present study, the ability of a saline soil bacteria (SSB)-consortium to degrade synthetic wastewater-phthalates with alkyl chains of different lengths, such as diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), and di (2-ethylhexyl) phthalate (DEHP) was characterized. A central composite design-response surface methodology was applied to optimize the degradation of each phthalate, where the independent variables were temperature (21–41 °C), pH (5.3–8.6) and PAE concentration (79.5–920.4 mg L−1), and Gas Chromatography-Mass Spectrometry was used to identify the metabolites generated during phthalate degradation. Optimal conditions were 31 °C, pH 7.0, and an initial PAE concentration of 500 mg L−1, where the SSB-consortium removed 84.9%, 98.47%, 99.09% and 98.25% of initial DEP, DBP, BBP, and DEHP, respectively, in 168h. A first-order kinetic model explained - the biodegradation progression, while the half-life of PAE degradation ranged from 12.8 to 29.8 h. Genera distribution of the SSB-consortium was determined by bacterial meta-taxonomic analysis. Serratia, Methylobacillus, Acrhomobacter, and Pseudomonas were the predominant genera; however, the type of phthalate directly affected their distribution. Scanning electron microscopy analysis showed that high concentrations (1000 mg L−1) of phthalates induced morphological alterations in the bacterial SSB-consortium. The metabolite profiling showed that DEP, DBP, BBP, and DEHP could be fully metabolized through the de-esterification and β-oxidation pathways. Therefore, the SSB-consortium can be considered a potential candidate for bioremediation of complex phthalate-contaminated water resources.

Thermally stable strongly fluorescent multi-stimuli responsive carbazole zwitterionic fluorophores: Alkyl chain length dependent thermofluorochromism and latent fingerprinting

Carbazole-picoline based π-conjugated zwitterionic fluorophores, (E)-3-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)propane-1-sulfonate (Cz-PS) and (E)-4-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)butane-1-sulfonate (Cz-BS) were synthesized and investigated the stimuli-responsive solid-state fluorescence properties. Cz-PS and Cz-BS displayed enhanced fluorescence in the solid-state (555 and 542 nm) with the quantum yield (Φf) of 32.9 and 28.5 %, respectively. Thermogravimetric analysis (TGA) indicated good thermal stability up to 300 °C for both Cz-PS and Cz-BS. Single crystal structural analysis of Cz-BS confirmed twisted molecular conformation and supramolecular interactions induced network structure, which lead to increase of solid-state fluorescence. Cz-BS showed mechanical stimuli-induced reversible/self-reversible fluorescence switching between two fluorescence states whereas Cz-PS did not show mechanofluorochromism. But both Cz-PS and Cz-BS showed acid/base dependent on–off reversible fluorescence switching in solution as well as solid-state. Further, both compounds also displayed reversible thermofluorochromism by heating and cooling. The yellow fluorescence of Cz-PS and Cz-BS was transformed to orange upon heating at 110 °C and cooling reversed the fluorescence to initial state. The good thermal stability and enhanced solid-state fluorescence of Cz-PS and Cz-BS were utilized for latent fingerprinting (LFP) application on various solid substrate. Particularly, LFP images of Cz-BS showed finger marks with well-defined features. Thus, integrating zwitterionic functionality produced strong solid-state fluorescence with multi-functional applications.

Fluorogenic Chemical Probe Strategy for Precise Tracking of Mitochondrial Polarity.

Mitochondrial polarity is a critical indicator of numerous pathological and biological processes; thus, the development of fluorescent probes capable of targeting mitochondria and visually monitoring its polarity is of great significance. In this study, fluorescent probes were designed with a N, N-dialkylamino rhodol scaffold as the fluorophore sensitive to polarity environments, in which the alkyl chain length was adjusted rationally to obtain distinct polarity recognition modes. By integrating mitochondria targeting groups, three fluorogenic chemical probes ROML-1, ROML-2, and ROML-3 have been obtained, featuring the capability to target mitochondria and monitor its polarity precisely, dynamically and visually. The probes displayed a distinctive response to the alterations in polarity. ROML-1 and ROML-2 followed a turn-on pattern while ROML-3 was ratiometric. It has been demonstrated that the hypersensitivity to polarity and ratio fluorescence property of ROML-3 was attributed to methyl groups rather than ethyl or butyl groups. The introduction of short methyl chains made the dihedral angle between the dialkylamino substituent and fluorophore of ROML-3 (spirocyclic form) rotatable and enlarged the energy gap between the ground state and excited state, which has been validated by the results of density functional theory (DFT) calculations. Furthermore, ROML-3 was used to monitor mitochondrial polarity via confocal microscopy imaging, which revealed that compared to healthy cells the polarity of mitochondria in cancer cells was enhanced; meanwhile, the polarity of mitochondria in senescent cells was higher in contrast with young cells. The present probe ROML-3 has been proven to be an efficient tool to monitor mitochondrial polarity dynamics, which demonstrated potential significance in biomedical research and disease diagnosis.

Miscibility Studies of Bismesogen CBnCB Forming Nematic Twist-Bend Phase with Cyanobiphenyls nCB.

This work aims to determine how the nematic twist-bend phase (NTB) of bismesogens containing two rigid parts of cyanobiphenyls connected with a linking chain containing n = 7, 9, and 11 methylene groups behaves in mixtures with structurally similar cyanobiphenyls nCB, n = 4-12, 14. The whole phase diagrams are presented for the CB7CB-nCB system. For the other systems, CB9CB-nCB and CB11CB-nCB, only curves corresponding to NTB-N phase transition are presented. Based on the temperature-concentration range of the existence of NTB phase, it was established that an increase in the alkyl chain length of CBnCB causes an increase in the stability of the NTB phase. But surprisingly, an increase in the alkyl chain length of nCB compounds does not change the slope of the NTB-N equilibrium line on phase diagrams. It is slightly bigger when the nCB compound has the same length of alkyl chain as the length of the linking group of a bismesogen. XRD studies were carried out for two mixtures.

Synthesis and characterization of new naphthalene diimides (NDIs) for application in electronic devices

This paper describes the synthesis of new naphthalene diimide (NDI) derivatives obtained in good yields from the reaction between 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) and different p-alkoxy-substituted anilines. The photophysical properties of the NDIs were investigated in solution and the solid state. UV–visible absorption spectra in 1,4-dioxane, dichloromethane, and acetonitrile showed absorption maxima at approximately 375 nm, related to symmetry and spin allowed 1π-π* electronic transitions. These compounds did not exhibit fluorescence emission in the studied solvents. Electrochemical studies have indicated that the presence of different alkyl chains significantly affects the capacity of NDIs when used as organic cathodes in Al-graphite batteries due to variations in their ability to intercalate tetrachloroaluminate. The organic cathodes incorporating NDIs with varying alkyl chain lengths exhibited distinct capacities: 123.5 mA h g⁻1 for 3a, 101.6 mA h g⁻1 for 3b, and 157.3 mA h g⁻1 for 3c, with a capacity retention of approximately 54 % after 15 charge‒discharge cycles. These findings highlight the crucial role of alkyl chain modification in optimizing the electrochemical performance of organic cathodes.

Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion.

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+ with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where N represents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+ and [TFSA]-, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N = 2-12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR-IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O-H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation's alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation's alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)-visible spectroscopic measurements on Ni2+-[CNmim][TFSA]-alcohol solutions with N = 2 and 8 revealed that di-, tetra-, and hexa-alcohol-Ni2+ complexes are formed in both the ILs. With N = 2, the stabilities of Ni2+-EtOH and Ni2+-MeOH complexes are comparable in the IL. However, with N = 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van't Hoff plots on the stability constants at several temperatures.

Formation and evolution of nanobubbles in CH4-H2O-Alcohol system: Insight into the effect of alcohol chain length from molecular dynamics simulations

Nanobubbles (NBs) which are gas filled cavities of nanometre dimensions present in liquids attracted increasing attention in the recent years due to their application in various fields such as chemistry, biology, medicine etc. An important aspect of NB research is the study of effect of additives on formation and evolution of these bubbles. The present study examined by applying molecular dynamics simulations, the formation and evolution of methane NBs in the CH4-H2O-Alcohol system, which is known to form during alcohol induced dissociation of CH4 hydrates in the natural gas extraction process. The effect of alcohol type and concentration on NB formation and evolution was examined through simulations of CH4-H2O-CH3OH, CH4-H2O-C2H5OH and CH4-H2O-nC3H7OH systems. The study revealed that increase in both concentration and the alkyl chain length of alcohols promoted NB formation. Alcohol molecules are found to enhance NB nucleation through accumulation near the NB-liquid interface resulting in a decrease in the surface tension (γ) at the interface. These effects become more pronounced as the alkyl chain length increases which explains the enhanced NB formation in systems containing nC3H7OH and C2H5OH compared to those containing CH3OH. The mechanism of formation and evolution of NBs is found to significantly depend on the type of alcohol present. NBs are found to nucleate at multiple locations in the systems containing nC3H7OH and C2H5OH which eventually coalesce to form a single large stable NB. In the presence of NBs which vary significantly in size, bubble growth was also found to occur through Ostwald ripening which involves transfer of CH4 from smaller NB to the larger one. In contrast, in the CH4-H2O-CH3OH system, primarily a single NB nucleated which grew in size through absorption of CH4 molecules dissolved in the liquid, rather than through coalescence or Ostwald ripening. The observed influence of alcohol type on the process of NB evolution is explained by examining the influence of alkyl chain length on γ and diffusivity of CH4 molecules. Due to the role of NBs on methane hydrate regeneration from the hydrate melt, we examined the influence of NB in the CH4-H2O-Alcohol system on the organization of water molecules (HSWs) present in the hydration shell of dissolved CH4. The value of F4 order parameter of HSWs and the number of hydrogen bonded water rings in the hydration shell of CH4 were analysed. The value of F4 order parameter indicate that the hydrophobic alkyl chain of alcohol induced hydrate like arrangement of HSWs, which is more pronounced in the case of alcohol with longer alkyl chain. However, alcohol molecules are also found to dislodge HSWs around CH4 resulting in a decrease in the number of water rings around dissolved CH4 which is not conducive to hydrate formation. These observations are consistent with the reported dual effect of alcohol on hydrate formation with alcohol promoting hydrate formation at low concentrations and inhibiting at high concentrations.

Homochiral Covalent Organic Frameworks with Superhelical Nanostructures Enable Efficient Chirality-Induced Spin Selectivity.

Despite significant advancements in fabricating covalent organic frameworks (COFs) with diverse morphologies, creating COFs with superhelical nanostructures remains challenging. We report here the controlled synthesis of homochiral superhelical COF nanofibers by manipulating pendent alkyl chain lengths in organic linkers. This approach yields homochiral 3D COFs 13-OR with a 10-fold interpenetrated diamondoid structure (R = H, Me, Et, nPr, nBu) from enantiopure 1,1'-bi-2-naphthol (BINOL)-based tetraaldehydes and tetraamine. COF-13-OEt exhibits macroscopic chirality as right-handed and left-handed superhelical fibers, whereas others adopt spherical or non-helical morphologies. Time-tracking shows a self-assembly process from non-helical strands to single-stranded helical fibers and intertwined superhelices. Ethoxyl substituents, being of optimal size, balance solvophobic effects and intermolecular interactions, driving the formation of superhelical nanostructures, with handedness determined by BINOL chirality. The superhelical nature of these materials is evident in their chiral recognition and spin-filter properties, showing significantly improved enantiodiscrimination in carbohydrate binding (up to six times higher enantioselectivity) and a remarkable chiral-induced spin selectivity (CISS) effect with a 48-51% spin polarization ratio, a feature absent in non-helical analogs.

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 a chemical stimulus 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 within several hours. 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 small molecule chemically responsive filamentous supramolecular polymers based on bolaamphiphilic monomers that can be irreversibly degraded in aqueous solutions for their eventual application as biomedical materials.