Longer Alkyl Chain Length Research Articles

New hydrogen-bonded liquid crystal supramolecular systems: role of (+ I)-alkoxy substituents in promoting molecular ordering

Novel H-bonded liquid crystals (HBLCs) are synthesized and examined for their mesomorphic behavior. The HBLCs are prepared with Schiff base proton acceptors containing 8 and 18 carbons in the alkyl chain and the proton donor with 4-substituted benzoic acids. All the compounds exhibit smectic A mesophases, with one of the compounds exhibiting LC properties below 298 K. It is interesting to note that the ethoxy-substituted HBLCs exhibit a wide range of thermal stability. Density functional theory calculations revealed the formation of two hydrogen bonds between the substituted acids and the pyridine ring based on the orientation of the donor and the acceptor moieties. There are no significant changes observed in the hydrogen bond length with the increase in the chain length of the proton acceptor moiety, indicating the dilution of the cores by the longer alkyl chain lengths is compensated with the (+ I) effect of alkoxy substituents. Quantum chemical modeling studies on these molecules revealed the reduction in the HOMO–LUMO energy gap by approximately 0.3 eV for oxy-containing compounds, making them more chemically reactive by donating electrons (+ I) into the aromatic cores. These materials provide a significant breakthrough in designing innovative LC materials. This work is in support of the SDG-9 of the United Nations.Graphical abstract

Cation Chain Length of Nonhalogenated Ionic Liquids Matters in Enhancing SERS of Cytochrome c on Zr-Al-Co-O Nanotube Arrays.

Surface-enhanced Raman scattering (SERS) is a remarkably powerful analytical technique enabling trace-level detection of biological molecules. The interaction of a probe molecule with the SERS substrate shows important distinctions in the SERS spectra, providing inherent fingerprint information on the probe molecule. Herein, nonhalogenated phosphonium-based ionic liquids (ILs) containing cations with varying chain lengths were used as trace additives to amplify the interaction between the cytochrome c (Cyt c) and Zr-Al-Co-O (ZACO) nanotube arrays, strengthening the SERS signals. An increased enhancement factor (EF) by 2.5-41.2 times compared with the system without ILs was achieved. The improvement of the SERS sensitivity with the introduction of these ILs is strongly dependent on the cation chain length, in which the increasing magnitude of EF is more pronounced in the system with a longer alkyl chain length on the cation. Comparing the interaction forces measured by Cyt c-grafted atomic force microscopy (AFM) probes on ZACO substrates with those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the van der Waals forces became increasingly dominant as the chain length of the cations increased, associated with stronger Cyt c-ZACO XDLVO interaction forces. The major contributing component, van der Waals force, stems from the longer cation chains of the IL, which act as a bridge to connect Cyt c and the ZACO substrate, promoting the anchoring of the Cyt c molecules onto the substrate, thereby benefiting SERS enhancement.

Extractive separation of citral and limonene with quaternary Ammonium/Alkanediol deep eutectic Solvents: An experimental and mechanistic study

As an aldehyde derivative of monoterpene, citral is the main oxyterpene in various botanical essential oils which has been widely applied in food, cosmetics and medicines. The separation of oxyterpenes from terpenes (deterpenation) improves its stability and quality, which is an essential step for production of citral with high market value. Herein, the extractive separation of citral and limonene using deep eutectic solvents (DESs) of quaternary ammonium/alkanediol was explored. Influence of DESs components, including different quaternary ammonium salts as hydrogen bond acceptors (HBAs), various alkanediols as hydrogen bond donors (HBDs) and the changing of HBA to HBD ratios on citral extraction were studied. Distribution coefficient, selectivity and extraction yield of the citral of these DESs were experimentally evaluated. Among the HBAs investigated, tetrabutylammonium bromide (TBABr) was determined to be the suitable one, since halide Br- was better than Cl-, and quaternary ammonium cations with longer alkyl chain length was preferable. Meanwhile, 1,2-propanediol (1,2-PDO) outperformed other alkanediols, and higher HBD contents in DESs facilitated the separation. TBABr/1,2-PDO (molar ratio 1:10) exhibited the best performance, with citral distribution coefficient 1.28, selectivity 13.65 and extraction yield 64.26%. The type and strength of molecular interactions between citral solute and DESs were identified by employing quantum chemistry calculation and molecular dynamic simulations. The performance difference of these DESs can be ascribed to the difference of the direct hydrogen bond between the α-OH of alkanediols and the O from citral carbonyl group during extraction. The mechanisms exploration provides insights for rational fine-tuning the novel DESs with better deterpenation performance.

Unveiling the Impact of Organic Spacer Cations on Auger Recombination in Layered Halide Perovskites

AbstractA library of large organic cation spacers is available for engineering the performance of layered two‐dimensional (2D) halide perovskite devices. Despite extensive photophysics studies, there remains a research gap over the structure‐function relations in 2D perovskites, especially the underlying factors influencing the Auger recombination (AR) process. Herein, the contributions of exciton binding energy, exciton‐phonon coupling, and defects/film morphology to the AR process in 2D perovskites are examined. Phenyl‐alkyl‐ammonium cations with different lengths of attached alkyl groups, commonly used in blue light‐emitting diodes, are investigated. The findings reveal an order of magnitude higher threshold carrier density for the AR onset as well as a reduced AR in cations with longer alkyl chain length. Although possessing similar exciton binding energies, the exciton‐phonon coupling strength is found to play a major role in reducing the AR rate, with a smaller contribution from the defect states/film morphology. The findings can help provide further guidance on organic spacer cation engineering for highly efficient 2D perovskite light emitters.

Effect of Alkylation Chain Length on Inhibiting Performance of Soluble Ionic Liquids in Water-Based Drilling Fluids.

This work investigated the effect of the alkyl chain length of soluble methylimidazolium bromide ionic liquids (ILs) on their inhibition performance. The IL with a shorter alkyl chain length showed superior inhibition performance by suppressing clay swelling, mitigating clay dispersion, at room temperature. Particularly, the IL with an alkyl chain length of two (EmBr) reduced the sodium bentonite (Na-BT) swelling degree to 89% and achieved a cutting recovery of 81.9% after being rolled at room temperature, performing the best among all ILs. To systematically analyze the inhibition mechanism of ILs, X-ray diffraction (XRD), ζ potential, and particle size distribution have been carried out. The results revealed that the methylimidazolium with shorter alkyl chain length had better ability to enter the interlayer void by ion exchange and decrease interlayer distance, suppress the electrical double layer of the Na-BT particles and decrease the ζ potential, and promote the aggregation of Na-BT in water. It is also observed that high hot rolling temperature reduced the shale inhibiting performance of all ILs, and ILs with longer alkyl chain length had better ability to prevent cutting disintegration at high temperature. It is attributed to the variation of the hydrophilic characteristic of Na-BT at high temperature where EmBr no longer adsorbed the most on the surface and entered the interlayer voids of Na-BT. This study can be used as a reference to systematically explore the effect of the structure of shale inhibitors on their inhibiting performance and develop effective shale inhibitors.

A combined QTAIM, DFT and molecular dynamics study on the nanoscale dynamical and structural organization of imidazolium-based dicationic ionic liquids

In this work, the effects of linkage alkyl chain length on the dynamical and structural micro-heterogeneities of some imidazolium-based dicationic ionic liquids (DILs) i.e. [Cn(mim)2][BF4]2, (n = 3, 6, 9, and 12) were studied via quantum mechanical calculations and also classical molecular dynamics (MD) simulations. Hydrogen bondings and also the interaction energies between the studied ions have been calculated using the density functional theory (DFT) calculations and also the quantum theory of atoms in molecules (QTAIM) method. The results showed that with increasing the linkage alkyl chain length of DILs, the interaction energies and electron densities are decreased, because the electrostatic interactions in DILs are weakened with increasing the –CH2 groups in the linkage chain. Different kinds of combined distribution functions (CDFs) were computed to better understand the orientations of ions in the studied DILs. Although, two rings of cation are almost perpendicular with respect to each other in all studied DILs, the orientation of linkage chain with respect to the rings is different in short- and long-linkage chain DILs. To understand the arrangement of the nearest neighboring ions, neighborhood analysis and spatial distribution functions (SDFs) of ions were analyzed. Furthermore, the mean square displacement (MSD), non-Gaussian parameter, van Hove correlation of cation and anions and also the ion pair, ion cage, hydrogen bond and reorientation dynamics were computed. DILs with longer alkyl chain length have more deviation in non-Gaussian parameter and Gaussian behavior of distribution of particle displacements, probably due to weakening the electrostatic interactions. Also, they have higher ion cage/ion pair stabilities than DILs with shorter linkage chain. Altogether, the linkage chain length in DILs has significant influences on their organizations in such a way that with increasing linkage chain length, their dynamical and structural micro-heterogeneities increase.

Effect of hydroxyl group on foam features of hydroxyl-based anionic ionic liquid surfactant: Experimental and theoretical studies

Ionic liquid surfactant (ILS) shows potential application in surfactant enhancing oil recovery (SEOR). The structure–activity relationship between structural characteristics and foam feature is significant for the design and selection of favorable ILS for foam enhanced oil recovery (FEOR). In this paper, the effect of structural substituent groups of anionic ILSs on foam features was established through experimental methods and Density functional theory (DFT) simulations. Physicochemical features of hydroxyl-based anionic ILS, 1-(2,3-dihydroxypropyl)-3-butylimidazolium dodecyl sulfate ([DPbim][DS]) was detected. By surface tensiometry, the critical micelle concentration (CMC) value of [DPbim][DS] was 0.427 mmol/L. Foam properties of three ILSs ([DPbim][DS], [Hmim][DS] (1-hexyl-3-methylimidazolium dodecyl sulfate), and [Bmim][DS] (1-butyl-3- methylimidazolium dodecyl sulfate), and sodium dodecyl sulfate (SDS) were established. The foam features of ILSs and SDS followed: [DPbim][DS] > [Hmim][DS] > [Bmim][DS] > SDS. ILS hydrates showed tendency: [Bmim][DS](H2O)n > [Hmim][DS](H2O)n > [DPbim][DS](H2O)n. D0 values followed the tendency: [DPbim][DS](H2O)n > [Hmim][DS](H2O)n > [Bmim][DS](H2O)n. Experimental and DFT results verified the introduction of hydroxyl group and longer alkyl chain length in imidazolium cation was favorable for foam features of ILSs. This information will help to screen new foam surfactants for FEOR.

Protic Ionic Liquid Cation Alkyl Chain Length Effect on Lysozyme Structure.

Solvents that stabilize protein structures can improve and expand their biochemical applications, particularly with the growing interest in biocatalytic-based processes. Aiming to select novel solvents for protein stabilization, we explored the effect of alkylammonium nitrate protic ionic liquids (PILs)-water mixtures with increasing cation alkyl chain length on lysozyme conformational stability. Four PILs were studied, that is, ethylammonium nitrate (EAN), butylammonium nitrate (BAN), hexylammonium nitrate (HAN), and octylammonium nitrate (OAN). The surface tension, viscosity, and density of PIL-water mixtures at low to high concentrations were firstly determined, which showed that an increasing cation alkyl chain length caused a decrease in the surface tension and density as well as an increase in viscosity for all PIL solutions. Small-angle X-ray scattering (SAXS) was used to investigate the liquid nanostructure of the PIL solutions, as well as the overall size, conformational flexibility and changes to lysozyme structure. The concentrated PILs with longer alkyl chain lengths, i.e., over 10 mol% butyl-, 5 mol% hexyl- and 1 mol% octylammonium cations, possessed liquid nanostructures. This detrimentally interfered with solvent subtraction, and the more structured PIL solutions prevented quantitative SAXS analysis of lysozyme structure. The radius of gyration (Rg) of lysozyme in the less structured aqueous PIL solutions showed little change with up to 10 mol% of PIL. Kratky plots, SREFLEX models, and FTIR data showed that the protein conformation was maintained at a low PIL concentration of 1 mol% and lower when compared with the buffer solution. However, 50 mol% EAN and 5 mol% HAN significantly increased the Rg of lysozyme, indicating unfolding and aggregation of lysozyme. The hydrophobic interaction and liquid nanostructure resulting from the increased cation alkyl chain length in HAN likely becomes critical. The impact of HAN and OAN, particularly at high concentrations, on lysozyme structure was further revealed by FTIR. This work highlights the negative effect of a long alkyl chain length and high concentration of PILs on lysozyme structural stability.

Binding of Sulfate-Terminated Surfactants with Different Alkyl Chain Lengths to Viologen Sites Covalently Embedded in the Interior of a Self-Assembled Monolayer on a Au Electrode

We investigated the binding of anionic surfactants of lower concentrations than their critical micelle concentrations (cmcs) to the cationic redox-active viologen site in the interior of a self-assembled monolayer (SAM) on a polycrystalline Au electrode. We embedded the viologen site in the midway of the alkyl chain to facilitate the ion-pairing binding, which depends on the oxidation state of the viologen. We found that the binding of anionic surfactants and inorganic anions causes a negative shift of the formal potential of the redox couple of the viologen radical cation/viologen dication in line with the binding equilibrium. In contrast, the anion binding was weak and trivial when viologens are located at the SAM surface, indicative of the enhancement of the binding by the electrostatic interaction in the microenvironment with the low dielectric constant. The negative shift of the formal potential of viologen in the interior was greater for the surfactants with longer alkyl chain lengths, indicative of the efficacy of the alkyl chain-chain interaction. The chain-length-dependent potential shift followed the linear Traube rule but with a smaller slope than that in the original rule. We also demonstrated that the conjugated layer of the viologen SAM with dodecyl sulfate at a lower concentration than the cmc completely blocks the direct electron transfer (ET) from the Au electrode to solution-phase Fe(CN)63- but allows mediated ET around the formal potential of the viologen.

Long-Range alignment of liquid crystalline small molecules on Metal-Organic framework micropores by physical anchoring

In this study, we are the first to observe the alignment behaviors of various assembling molecules with different feature sizes and shapes, including rod-, disc-, and column-shaped molecules, on zeolitic imidazolate framework-8 (ZIF-8) surfaces. Among the various rod-shaped 4-alkyl-4′-cyanobiphenyls (nCBs), those with short alkyl chains with less than nine hydrocarbons (e.g., 5CB, 6CB, 8CB, and 9CB) were vertically aligned on the ZIF-8 surface, while nCBs with long alkyl chains with more than 10 hydrocarbons (e.g., 10CB and 11CB) were randomly oriented on the surface. Unlike rod-shaped small molecules, the disc- and column-shaped molecules were randomly oriented on the ZIF-8 surface. A molecular dynamic simulation revealed that the vertical alignment of rod-shaped molecules on the ZIF-8 surface can be attributed to physical anchoring by the ZIF-8 micropores. Most portions of the alkyl chain of nCB with shorter alkyl chain lengths (n ≤ 9) can be inserted into the ZIF-8 aperture, while nCBs with longer alkyl chain lengths (n > 9) cannot be adequately anchored in the ZIF-8 aperture. According to these results, we believe that MOF materials with micropores can offer an effective tool for controlling the orientation of various functional small molecules.

Ion Dynamics and Transport Properties of Lewis-Acidic Imidazolium Chloroaluminate Ionic Liquids

Ion dynamics and charge transport are investigated in a series of Lewis-acidic 1-alkyl-3-methylimidazolium chloroaluminate ionic liquids (2:1 mole ratio AlCl3:C n MIm Cl, n = 2, 4, 6, 8) and the chloride-based IL starting materials 1-hexyl-3-methylimidazolium chloride (C6MIm Cl) and 1-octyl-3-methylimidazolium chloride (C8MIm Cl) via broadband dielectric spectroscopy, shear rheology, and differential scanning calorimetry. A detailed analysis of the dielectric and mechanical spectra reveals the emergence of mesoscale polar/non-polar aggregate dynamics at longer alkyl chain lengths. The observed influence of cation and anion chemical structure on the dielectric signature of mesoscale aggregate dynamics is interpreted according to a recently discovered link between these dynamics and the local shape of non-polar domains. Furthermore, conductivity relaxation and dipole reorientation processes are probed by employing a simultaneous analysis of the dielectric spectra in the complex conductivity, permittivity, and electric modulus representations. The temperature dependent rates of the observed dielectric relaxation processes are contrasted with the rates of structural relaxation evaluated by shear rheology. The results confirm the close coupling of charge transport and structural rearrangement typical of aprotic ionic liquids; however, notable separation in the rates probed by the various dielectric representations indicate ion dynamics may be significantly more heterogeneous in the chloroaluminate ILs. In particular, the rates attributed to cation translational and rotational motion are found to be considerably slower than the rate of structural relaxation. Identifying this dynamic heterogeneity and elucidating its molecular origin is critical to understanding the transport properties of this IL class and promoting rational design of future ILs.

Chain flexibility and glass transition temperatures of poly(n-alkyl (meth)acrylate)s: Implications of tacticity and chain dynamics

The relationship between chain microstructure and glass transition temperature (Tg) is complicated for poly(alkyl methacrylate)s and poly(alkyl acrylate)s. Despite intensive studies, relationships between the structures of these polymers and their properties, including solution characteristics and Tg, are still controversial. Solution properties, chain conformations, including Flory's characteristic ratio (C∞), persistence length (lp), and chain diameters, and Tg are reported for series of poly(n-alkyl acrylate)s and poly(n-alkyl methacrylate)s having alkyl side chain lengths (n) ranging from 1 to 10 carbons in length, with uniform and well-characterized tacticities. Chain flexibilities of both series of polymers decrease as n increases, reflecting increased hindrances to rotation about backbone bonds as side chains become longer. Conversely, the Tgs for both series of polymers decrease substantially as n increases, reflecting the greater side chain mobilities of long alkyl substituents. For shorter alkyl chain lengths, Tgs for the poly(n-alkyl acrylate)s are much lower than for the corresponding poly(n-alkyl methacrylate)s, a difference which has been attributed in the past to the presumed reduced chain flexibility of polymethacrylates due to the presence of the α-methyl substituent. However, contrary to such expectations, C∞ and lp values for these two series of polymers are nearly identical at a given n value, except for the longest n-alkyl substituents. Instead, the differences in Tg may be attributed to the differences in tacticity of the two series – almost ideally atactic for the poly(n-alkyl acrylate)s but high in syndiotacticity for the poly(n-alkyl methacrylate)s. The Tgs for the two series of polymers approach that of polyethylene at longer alkyl chain lengths. In addition, the effects of tacticity and chain dynamics on C∞, lp, and Tg of poly(methyl methacrylate) is discussed.

Interactions of CO2 with the homologous series of СnMIMBF4 ionic liquids studied in situ ATR-FTIR spectroscopy: spectral characteristics, thermodynamic parameters and their correlation

In this work, in situ ATR-FTIR spectroscopy was used to study the interaction of CO2 and a series of 1-alkyl-3-methylimidazolium tetrafluoroborate СnMIMBF4 (n = 2, 4, 6, 8, 10) ionic liquids. A detailed analysis of the infrared spectra acquired from ionic liquids and sorbed СО2 was performed as ionic liquids with different the alkyl chain lengths were subjected to changing pressures of СО2 and temperature. With a longer alkyl chain length, an increase in the shift of the CH stretching vibrations bands of alkyl groups and BF stretching vibrations of BF4− anions is observed during CO2 sorption. This indicates the disaggregation of alkyl chains and anions. There is a correlation with the position of the wavenumber of the ν3 asymmetric stretching CO2 band and the length of the alkyl chain. It was found that some of the CO2 adsorbed by ionic liquids does not interact with the ionic liquid but is “free” in the bulk of the alkyl chains. For the first time, ATR-FTIR spectroscopy was used to determine the thermodynamic parameters of CO2 sorption in ionic liquids. It was demonstrated that the values of enthalpy and entropy obtained by analysis of the ATR-FTIR spectra are consistent the data obtained by other methods. A correlation was found between the enthalpy of sorption of CO2 and the wavenumber of the ν3 band. This opens up the possibility of using CO2 as an IR-sensitive probe molecule to characterize the acid-base properties of ionic liquids and determine the enthalpy of CO2 sorption.

AIE-active electrochromic materials based on tetraphenylethylene cored benzoates with high optical contrast and coloration efficiency

In this work, a series of dual functional materials, 4,4′,4″,4‴-(ethene-1,1,2,2-tetrayl)tetrabenzoates (ETBAs), were developed with an aggregation-induced emission (AIE) luminogenic center (tetraphenylethylene) and electrochromically active moieties (benzoates). The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of the ETBAs were determined via density functional theory calculations. The fluorescent, electrochemical, and electrochromic performances of the ETBAs were characterized via fluorescence spectroscopy, cyclic voltammetry, UV–Vis spectroscopy, and chronoamperometry. All the ETBAs demonstrated an AIE effect in water/N-methyl pyrrolidone. The ETBAs underwent a quasi-reversible reduction-oxidation. Electrochromic devices based on the ETBAs exhibited a significant color change from a transparent bleached state to a colored blue state, high optical contrast (ca. 80%), and large coloration efficiency. The used substituents markedly influenced the cyclability and response time, and compounds with a larger conjugation degree had lower energy gap values and faster response time. Compound c with a longer alkyl chain length had the best performance with regards to coloration efficiency and cyclability. In summary, this work demonstrated a strategy for the design of novel high-performance ECMs and could extend the applications of such multi-functional materials.

Liquid Structure and Dynamics of Tetraalkylammonium Bromide-Based Deep Eutectic Solvents: Effect of Cation Chain Length.

Deep eutectic solvents (DESs) have emerged in recent years as environmentally sustainable media across several fields. However, knowledge of liquid structure, dynamics, and solute-solvent interactions in many DESs that is essential for exploiting their potential is still lacking. In this work, we make an attempt to obtain some insight into these aspects of a set of less-explored DESs comprising tetraalkylammonium bromide salts and ethylene glycol (EG) by monitoring the fluorescence response of some carefully chosen dipolar (C153 and 4-AP) and nonpolar (9-PA) solutes in these media. Specifically, we have studied the translational and rotational diffusion dynamics of these molecular systems using single-molecule-based fluorescence correlation spectroscopy technique and ensemble-based time-resolved fluorescence anisotropy measurements. These results point to spatial and dynamic heterogeneity of these DESs, which becomes prominent in systems comprising cations with a longer alkyl chain length. This study reveals that diffusion dynamics of the probe molecules is determined not only by the solvent bulk viscosity but also dependent on their microenvironments and solute-solvent interactions experienced in these media.

Recycling of Polysilicon Byproduct SiCl4 Dissolved in Ionic Liquids

Silicon tetrachloride (SiCl4) is one of the primary by-products products of the polysilicon industries, which must also be handled with care, as it is both toxic and reactive. The dissolution of SiCl4 and electrodeposited of Si in ionic liquids (ILs) was investigated. Six kinds of ILs were examined as the solvents; the cations were 1-Butyl-3-methylimidazolium 1-butyl-3-methylimidazolium ([Bmim]+), 1-Hexyl-3-methylimidazolium ([Hmim]+), 1-Octyl-3-methylimidazolium ([Omim]+), N-butyl-3-methylpyridinium ([B3MePy]+), N-hexyl-3-methylpyridinium ([H3MePy]+), N-octyl-3-methylpyridinium ([O3MePy]+); the anion was bis[(trifluoromethyl)sulfonyl]imide ([NTf2]−). The results indicated that a decrease in the solubility of SiCl4 in ILs followed an increase in temperature. The presence of Si-O bonding between the ionic liquid and SiCl4 enhanced the SiCl4 dissolving capacity of in the ILs with anion of [NTf2]−. Longer alkyl chain lengths in the imidazolium and pyridinium cations of the ILs exhibited a better performance in dissolving SiCl4, due to the presence of C-Cl and C-Si formed between the ILs and SiCl4. Si was electrodeposited on a Ti plate under potential of 2.92V, of which a Si weight of up to 28.43 wt% was observed. The deposition product on the electrode is in the coexistence state of Si and SiOx due to the deposition conditions at ordinary temperature and pressure.

Deciphering interactions of ionic liquids with biomembrane.

Ionic liquids (ILs) are a special class of low-temperature (typically < 100°C) molten salts, which have huge upsurge interest in the field of chemical synthesis, catalysis, electrochemistry, pharmacology, and biotechnology, mainly due to their highly tunable nature and exceptional properties. However, practical uses of ILs are restricted mainly due to their adverse actions on organisms. Understanding interactions of ILs with biomembrane is prerequisite to assimilate the actions of these ionic compounds on the organism. Here, we review different biophysical methods to characterize interactions between ILs and phospholipid membrane, a model biomembrane. All these studies indicate that ILs interact profoundly with the lipid bilayer and modulate the structure, microscopic dynamics, and phase behavior of the membrane, which could be the fundamental cause of the observed toxicity of ILs. Effects of ILs on the membrane are found to be strongly dependent on the lipophilicity of the IL and are found to increase with the alkyl chain length of IL. This can be correlated with the observed higher toxicity of IL with the longer alkyl chain length. These informations would be useful to tune the toxicity of IL which is required in designing environment-friendly nontoxic solvents of the so-called green chemistry for various practical applications.

Synthesis of inulin derivatives with quaternary phosphonium salts and their antifungal activity

Inulin is a kind of renewable and biodegradable carbohydrate with good water solubility and numerous physiological functions. For further utilization of inulin, chemical modification can be applied to improve its bioactivities. In this paper, five novel inulin derivatives were synthesized via chemical modification with quaternary phosphonium salt. Their antifungal activity against three kinds of plant pathogens including Colletotrichum lagenarium, Phomopsis asparagi, and Fusarium oxysporum was assessed with radial growth assay in vitro. Results revealed that all the inulin derivatives exhibited improved antifungal activity compared with inulin. Particularly, inulin modified with triphenylphosphine (TPhPAIL) exhibited the best antifungal activity with inhibitory indices of 80.0%, 78.8%, and 87.4% against Colletotrichum lagenarium, Phomopsis asparagi, and Fusarium oxysporum at 1.0mg/mL respectively. The results clearly showed that chemical modification of inulin with quaternary phosphonium salt could efficiently improve derivatives' antifungal activity. Further analysis of results indicated that the antifungal activity was influenced by alkyl chain length or electron-withdrawing ability of the grafted quaternary phosphonium salts. Longer alkyl chain lengths or the stronger electron-withdrawing groups would lead to enhanced antifungal efficacy.

Impact of the alkyl chain length on binding of imidazolium-based ionic liquids to bovine serum albumin

The effects of six imidazolium-based ionic liquids (ILs) with different alkyl chain length ([CnMim]Cl, n=2, 4, 6, 8, 10, 12) on the structure and functions of bovine serum albumin (BSA) were studied by multi-spectral methods and molecular docking. ILs with the longer alkyl chain length have the stronger binding interaction with BSA and the greater conformational damage to protein. The effects of ILs on the functional properties of BSA were further studied by the determination of non-enzyme esterase activity, β-fibrosis and other properties of BSA. The thermal stability of BSA was reduced, the rate of the formation of beta sheet structures of BSA was lowered, and the esterase-like activity of BSA were decreased with the increase of ILs concentration. Simultaneous molecular modeling technique revealed the favorable binding sites of ILs on protein. The hydrophobic force and polar interactions were the mainly binding forces of them. The calculated results are in a good agreement with the spectroscopic experiments. These studies on the impact of the alkyl chain length on binding of imidazolium-based ionic liquids to BSA are of great significance for understanding and developing the application of ionic liquid in life and physiological system.

Raman Spectroscopy Characterization of Dissolved Polysilicon Byproduct SiCl4 in Ionic Liquids

Silicon tetrachloride (SiCl4) is the main byproducts of the polysilicon industries. The dissolution behaviors of SiCl4 in imidazolium ionic liquid, including [Bmim]OTf, [Bmim]NTf2, [Hmim]NTf2, and [Omim]NTf2, were investigated for recycling Si from SiCl4. Raman spectroscopy was used to understand the combination between the ionic liquid and SiCl4, and the conductivity of ionic liquids in different conditions was determined. The results indicated that [Bmim]NTf2 exhibited a better SiCl4 dissolving capacity compared to [Bmim]OTf, longer alkyl chain lengths in the imidazolium cations of the ionic liquids exhibited a better performance in dissolving SiCl4, and [Bmim]NTf2 : PC = 1 : 2 exhibited the best conductivity. In addition, molecular bondings between C-Cl, Si-O-Si, and C-Si were formed between the ionic liquids and SiCl4.