Nonpolar Organic Solvents Research Articles

Synthesis and properties of gallate ionic liquids

An efficient method for the synthesis of novel antioxidants in the form of ionic liquids (ILs) was described in the framework of this study. The ILs were obtained by the reaction of quaternary ammonium hydroxides with gallic acid as well as the protonation of amphoteric betaine. The following physicochemical properties of the obtained ILs were characterized: solubility in water as well as in polar and non-polar organic solvents, octanol–water partition coefficient, thermal stability, and surface activity. The investigation of bactericidal activity indicated that the synthesized gallates exhibited high efficacy against bacteria, especially against Bacillus subtilis. The DPPH radical scavenging assay confirmed the antioxidant properties of gallate ILs.

Actual aspects of the chemistry of dipyrrin dyes and prospects for their application in molecular sensorics

The results of research on the correlation between molecular structure and spectral luminescent and photophysical properties for a new class of dyes and luminophores based on dipyrrins, bis(dipyrrins), and their coordination compounds in different media are summarized. The new perspective applications of dipyrrin dyes and luminophores as fluorescent sensors for measuring the polarity, viscosity, and temperature of the medium and highly sensitive and selective fluorescent “off-on” chemosensors for detecting Zn2+, Cd2+, and Hg2+ cations in weakly polar and nonpolar organic solvents and biological systems are discussed.

The Complete Water-Based Ceramic Coating Process for Lithium Secondary Batteries By Plasma Treatment

Numerous numbers of polyolefin-based microporous separators containing thermally stable inorganic/polymer composite layers have been developed to improve safety of lithium-ion batteries [1-3]. Because of hydrophobic surface property of polyolefin-based separators, the use of non-polar organic solvent, which is generally toxic and expensive, is prerequisite to introduce ceramic coating layers containing polymeric binders. Not only to price down the coating process but also to guarantee an environmentally friendly coating process, an aqueous ceramic coating process should be developed. Herein, we developed the complete water-based ceramic coating process to prepare inorganic/polymer composite coating layers on commercial polyethylene (PE) separators using plasma treatment. The plasma treatment introduced polar functional groups onto the surface of PE separators, thereby changed the surface properties of the PE separators from hydrophobic to hydrophilic. Consequently, the coating solution based on water uniformly covered the plasma treated PE separator surfaces without defects. We investigated the physical properties of ceramic-coated separators (CCSs), including their morphology changes, gurley number, thickness, and ionic conductivity. We also studied the electrochemical properties of cells containing the CCSs. CCS exhibits superior power capability and cycle performance compared to bare PE in unit cells based on lithium metal anodes. Acknowledges This research was supported by the Ministry of Trade, Industry & Energy (MOTIE), Korea Institute for Advancement of Technology (KIAT) through the Encouragement Program for The Industries of Economic Cooperation Region (G02A01280032701) Reference [1] Y. Lee, H. Lee, T. Lee, M.-H. Ryou, Y.M. Lee, J. Power Sources 294 (2015) 537-544. [2] D. Yeon, Y. Lee, M.-H. Ryou, Y.M. Lee, Electrochim. Acta 157 (2015) 282-289. [3] H. Jeon, D. Yeon, T. Lee, J. Park, M.-H. Ryou, Y.M. Lee, J. Power Sources 315 (2016) 161-168.

Photoinduced Spontaneous Free-Carrier Generation of (7,5)-Chirality-Enriched Single-Walled Carbon Nanotubes in a Low Dielectric Solvent

We demonstrate photoinduced spontaneous free-carrier generation in highly individualized (7,5)- chirality-enriched SWCNT samples ((7,5)-SWCNTs) suspended in a non-polar organic solvent. Frequency-resolved solution-phase flash photolysis time-resolved microwave conductivity (fp- TRMC), provides a contactless and quantitative measurement of the real and imaginary photoconductance of these individually suspended nanotubes. We use substantially lower excitation fluences than have been possible in previous studies, corresponding to absorbed photon densities of ~0.05 photons per micron length of (7,5)-SWCNTs, allowing us to avoid complications from dielectric screening by nearby excitons or exciton-exciton collisions. Even under these mild conditions, we unambiguously measure a photoconductance due to free carriers that are generated following excitation of both the first and second exciton transitions (S11 and S22, respectively). The low-fluence carrier generation quantum yield (Φ) with S22 excitation appears c.a. 2.4 times higher than that with S11 excitation, suggesting that the autoionization of S22 excitons clearly enhances the carrier generation efficiency. In contrast, the transient decay dynamics are independent of excitation wavelength, suggesting that the mobile carriers generated from either S11 or S22 excitation undergo identical decay pathways (i.e. trapping, recombination, etc.).

Comparison Study on the Stability of Copper Nanowires and Their Oxidation Kinetics in Gas and Liquid.

The unsaturated "dangling" bonds on the surface of nanomaterials are extremely sensitive to the external environment, which gives nanomaterials a dual nature, i.e., high reactivity and poor stability. However, studies on the long-term effects of stability and reactivity of nanomaterials under practical conditions are rarely found in the literature and lag far behind other research. Furthermore, the long-term effects on the stability and reactivity of a nanomaterial without coating under practical conditions are seriously long-neglected. Herein, by choosing copper nanowire as an example, we systematically study the stability of copper nanowires (CuNWs) in the liquid and gas phase by monitoring the change of morphology, phase, and valence state of CuNWs during storage. CuNWs exhibit good dispersibility and durable chemical stability in polar organic solvents, while CuNWs stored in water or nonpolar organic solvents evolve into a mace-like structure. Additionally, fresh CuNWs are oxidized into CuO nanotubes with thin shells by heating in air. The activation energies of oxidation of CuNWs in the gas phase are determined by the Kissinger method. More importantly, the different oxidation pathways have significant effects on the final morphology, surface area, phase, optical absorption, band gap, and vibrational property of the oxidation products. Understanding the stability and reactivity of Cu nanostructures will add value to their storage and applications. This work emphasizes the significant issue on the stability of nanostructures, which should be taken into account from the viewpoint of their practical application.

Analysis of Comparative Sequence and Genomic Data to Verify Phylogenetic Relationship and Explore a New Subfamily of Bacterial Lipases

Thermostable and organic solvent-tolerant enzymes have significant potential in a wide range of synthetic reactions in industry due to their inherent stability at high temperatures and their ability to endure harsh organic solvents. In this study, a novel gene encoding a true lipase was isolated by construction of a genomic DNA library of thermophilic Aneurinibacillus thermoaerophilus strain HZ into Escherichia coli plasmid vector. Sequence analysis revealed that HZ lipase had 62% identity to putative lipase from Bacillus pseudomycoides. The closely characterized lipases to the HZ lipase gene are from thermostable Bacillus and Geobacillus lipases belonging to the subfamily I.5 with ≤ 57% identity. The amino acid sequence analysis of HZ lipase determined a conserved pentapeptide containing the active serine, GHSMG and a Ca2+-binding motif, GCYGSD in the enzyme. Protein structure modeling showed that HZ lipase consisted of an α/β hydrolase fold and a lid domain. Protein sequence alignment, conserved regions analysis, clustal distance matrix and amino acid composition illustrated differences between HZ lipase and other thermostable lipases. Phylogenetic analysis revealed that this lipase represented a new subfamily of family I of bacterial true lipases, classified as family I.9. The HZ lipase was expressed under promoter Plac using IPTG and was characterized. The recombinant enzyme showed optimal activity at 65°C and retained ≥ 97% activity after incubation at 50°C for 1h. The HZ lipase was stable in various polar and non-polar organic solvents.

Aza-fluorocyclization of nitrogen-containing unsaturated compounds

Abstract The aza-fluorocyclization of unsaturated nitrogen-containing compounds is reviewed. Syntheses of diverse fluorinated heterocycles by means of aza-fluorocyclization protocol are presented. The mechanism of the aza-fluorocyclization reactions, application of transition metals, and anionic phase-transfer catalysts are discussed. Advantages in the application of new strong electrophilic N–F reagents, including chiral [N–F] + compounds soluble in non-polar organic solvents, are presented. The reactivity of various N–F reagents is validated. The influence of the nature of transition metals catalysts, fluorinating reagents and solvents on the stereoselectivity of the fluorocyclization is discussed. The asymmetric fluorination by application of chiral organic oxidants and anionic phase-transfer catalysts is presented. Recent development dealing with the application of metal-catalysis in the syntheses of heterocyclic compounds by aza-fluorocyclization protocol is reviewed. The review covers the literature from 2011 to June 2015. References to some earlier publications are given to compare the results which are discussed.

Highly organic phase soluble polyisobutylene-bound cobalt phthalocyanines as recyclable catalysts for nitroarene reduction

A cobalt phthalocyanine (CoMPc) containing covalently linked polyisobutylene (PIB) groups as phase anchors that is both highly soluble in nonpolar organic solvents and phase selectively soluble in a liquid/liquid separation step is shown to be an effective recyclable homogeneous catalyst for nitroarene reduction in a semi-thermomorphic system. Electron-donating and electron-withdrawing substituents in the nitroarene are tolerated in this aniline synthesis and the catalyst is recyclable up to 10cycles with little leaching and no detectable loss in reactivity after 10cycles.

How the Type of Cosurfactant Impacts Strongly on the Size and Interfacial Composition in Gemini 12-2-12 RMs Explored by DLS, SLS, and FTIR Techniques.

The limited amount of information about reverse micelles (RMs) made with gemini surfactants, the effect of the n-alcohols in their interface, and the water-entrapped structure in the polar core motivated us to perform this work. Thus, in the present contribution, we use dynamic light scattering (DLS), static light scattering (SLS), and FT-IR techniques to obtain information on RMs structure created, with the gemini dimethylene-1,2-bis(dodecyldimethylammonium) bromide (G12-2-12) surfactant and compare the results with its monomer: dodecyltrimethylammonium bromide (DTAB). In this way, the size of the aggregates formed in different nonpolar organic solvents, the effect of the chain length of n-alcohols used as cosurfactants, and the water-entrapped structure were explored. The data show that the structure of the cosurfactant needed to stabilize the RMs plays a fundamental role, affecting the size and behavior of the aggregates. In contrast to what happens with the RMs formed with the monomer DTAB, water entrapped inside G12-2-12 RMs displays different interaction with the interface depending on the hydrocarbon chain length of the n-alcohol used as cosurfactant. Thus, n-pentanol and n-octanol molecules are located in different regions in the RMs interfaces formed with the gemini surfactant. n-Octanol locates at the RMs interface among the surfactant hydrocarbon tails increasing the water-surfactant polar headgroup interaction. On the other hand, n-pentanol locates at the RMs interface near the polar core, limiting the interaction of water with the micellar inner interface and favoring the water-water interaction in the polar core.

Functionalised graphene-multiwalled carbon nanotube hybrid poly(styrene-b-butadiene-b-styrene) nanocomposites

Combinations of functionalised graphene (fG) and functionalised multiwalled carbon nanotubes (fMWCNT) were dispersed into poly(styrene-b-butadiene-b-styrene) (SBS) matrix, where the ratios of individual fillers were varied in each nanocomposite. The synthesis of fG started from thermal expansion of expandable graphite (EG), followed by modified Hummer's method to produce graphene oxide (GO), and functionalisation of GO with 1-bromobutane (C4H9Br). The resultant fG displayed stable and strong compatibility to non-polar organic solvents. The polymer nanocomposites were prepared and characterised for their morphology, thermal stability, mechanical properties and electrical conductivity. Polymer nanocomposites with hybrid nanofillers showed improvement in thermal and electrical properties than their single nanofiller counterparts. Both the properties have maximum improvement with same weight ratios of fG and fMWCNT, with each 1.5%·w/w in SBS matrix. For mechanical properties, the improvement depends on the dominance of nanofiller. For the hybrid nanofillers, fG improved the elastic behaviour of SBS, while fMWCNT gave the overall stiffness.

Effect of the size of solvent molecules on the single-chain mechanics of poly(ethylene glycol): implications on a novel design of a molecular motor.

Excluded-volume (EV) interaction, also known as the EV effect, can drive the collapse of polymer chains in a polymer solution and promote the crystallization of polymer chains. Herein we report, for the first time, the effect of EV interaction on the single-chain mechanics of a polymer, poly(ethylene glycol) (PEG). By using AFM-based single-molecule force spectroscopy, the single-chain mechanics of a PEG chain has been detected in various nonpolar organic solvents with different molecule sizes. It is observed that the nonpolar solvents can be classified into two categories. In the small-sized organic solvents (e.g., tetrachloroethane and n-nonane), PEG presents its inherent elasticity, which is consistent with the theoretical single-chain elasticity from quantum mechanical calculations. However, in the middle-sized solvents (e.g., n-dodecane and n-hexadecane), the single-chain entropic elasticity of PEG is influenced by EV interactions noticeably, which indicates that the PEG chain tends to adopt a compact conformation under these conditions. To stretch a PEG chain from a free state to a fully extended state, more energy (1.54 kBT per repeating unit) is needed in small-sized organic solvents than in middle-sized organic solvents. It is expected that a partially stretched PEG chain would shrink to some extent when the solvent is changed from a middle-sized organic solvent to a small-sized one. Accordingly, a novel design of a PEG-based single-molecule motor that works with solvent stimuli is proposed.

Mesoporous manganese oxide for the degradation of organophosphates pesticides

Manganese(IV) oxide used for degradation of toxic organophosphorus compounds was prepared by homogeneous hydrolysis of potassium permanganate (KMnO4) with 2-chloroacetamide. The prepared sample was characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and nitrogen physisorption. The degradation efficiency was determined with parathion methyl (PM) as representative of organophosphate pesticides using high-performance liquid chromatography. For a comparison, the commercially obtained product and the two synthesized manganese(IV) oxides prepared by direct reaction of manganese(II) sulfate (MnSO4·H2O) and potassium permanganate (KMnO4) and potassium permanganate (KMnO4) with urea in aqueous solution were tested. The sample prepared by homogeneous hydrolysis of KMnO4 with 2-chloroacetamide showed the highest degradation efficacy. The reaction half-time in non-polar organic solvent (n-heptane) was around 0.9 min with the degradation efficiency of about 90 % within 2 h. It was shown that comparative samples of manganese(IV) oxides were variously effective in decomposition of PM by cleavage of the P–O-aryl bond in the pesticide molecule. The degradation mechanism for PM on the MnO2 surfaces was proposed.

Polarity‐reversal‐producing phase transfer of hydrophilic silver nanoclusters capped by a hyperbranched polymer from water to nonpolar organic solvents

ABSTRACTHyperbranched poly(ethylene imine) (PEI)‐capped Ag nanoclusters, synthesized starting from an aqueous environment, dispersed well in water and most polar organic solvents. However, with the addition of 1,4‐dioxane, the PEI‐capped Ag nanoclusters could be separated completely to obtain hydrophilic and hydrophobic Ag nanoclusters. Through this facile method, the successful phase transfer of PEI‐capped Ag nanoclusters from the aqueous phase to the nonpolar organic phase, such as from water to carbon tetrachloride, chloroform, and methylene bichloride, was easily realized. The polarity reversal of Ag nanoclusters were considered to be associated with the conformational change of PEI on the basis of the hydrophobic methylene groups of polymer backbone facing the external side or internal side, and this polarity reversal was irreversible. Moreover, PEIs with higher molecular weights showed a higher efficiency of phase transfer of the Ag nanoclusters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43206.

Structural Degradation and Swelling of Lipid Bilayer under the Action of Benzene.

Benzene and other nonpolar organic solvents can accumulate in the lipid bilayer of cellular membranes. Their effect on the membrane structure and fluidity determines their toxic properties and antibiotic action of the organic solvents on the bacteria. We performed molecular dynamics simulations of the interaction of benzene with the dimyristoylphosphatidylcholine (DMPC) bilayer. An increase in the membrane surface area and fluidity was clearly detected. Changes in the acyl chain ordering, tilt angle, and overall bilayer thickness were, however, much less marked. The dependence of all computed quantities on the benzene content showed two regimes separated by the solubility limit of benzene in water. When the amount of benzene exceeded this point, a layer of almost pure benzene started to grow between the membrane leaflets. This process corresponds to the nucleation of a new phase and provides a molecular mechanism for the mechanical rupture of the bilayer under the action of nonpolar compounds.

Luminescent neutral lanthanide complexes of 5-aryl-2,2′-bipyridine-6-carboxylic acids, synthesis and properties

Luminescent lanthanide complexes of 4-aryl-1-(2-pyridyl)-6,7-dihydro-5H-cyclopenta[c]pyridine-3-carboxylic acids and 5-tolyl-2,2′-bipyridine-6-carboxylic acid were prepared. The ligands were synthesized using the “1,2,4-triazine” methodology. In one case, the opportunity of copper complex preparation, followed by exchange of the metal cation from copper to europium to overcome synthetic difficulties, was demonstrated. The ability of tuning the properties of the complexes by means of varying the structure of the ligands was demonstrated. In particular, the introduction of the cyclopentene moiety allowed the preparation of highly soluble complexes in non-polar organic solvents.

Grubbs-Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids.

The novel dicationic metathesis catalyst [(RuCl2(H2ITapMe2)(=CH–2-(2-PrO)-C6H4))2+ (OTf−)2] (Ru-2, H2ITapMe2 = 1,3-bis(2’,6’-dimethyl-4’-trimethylammoniumphenyl)-4,5-dihydroimidazol-2-ylidene, OTf− = CF3SO3−) based on a dicationic N-heterocyclic carbene (NHC) ligand was prepared. The reactivity was tested in ring opening metathesis polymerization (ROMP) under biphasic conditions using a nonpolar organic solvent (toluene) and the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM+][BF4−]. The structure of Ru-2 was confirmed by single crystal X-ray analysis.

Formation of Titania-Silica Mixed Oxides in Solvent Mixtures and Their Influences for the Photocatalytic CO2 Conversion to Hydrocarbon.

TiO2-SiO2 mixed oxide photocatalyst materials responsive to simulated solar light illumination have been synthesized by sol-gel method in various polar and nonpolar organic solvent mixtures. The photocatalysts were characterized by numerous experimental techniques and investigated for the photocatalytic conversion of CO2 to CH4. The TiO2-SiO2 mixed oxide photocatalysts prepared in the presence of nonpolar aromatic solvents such as xylene, toluene or benzene along with ethanol show high surface area, huge mesoporosity and enormous pore volume compared to the materials conventionally synthesized in a mixture of ethanol and hexane. The TiO2-SiO2 mixed oxide photocatalyst prepared in benzene along with ethanol yields 21.0 ppm g(-1) h(-1) of methane production; however the material synthesized in hexane shows negligible amount of methane production under simulated solar light irradiation. These results indicate that aromatic nonpolar solvents can tune the textural properties of photocatalysts compared to non-polar aliphatic solvents.

Fluorescence-enhanced gels of D–π–A diphenylacrylonitrile derivatives: Influence of nitro group and alkoxy chain

4-nitrodiphenylacrylonitrile and diphenylacrylonitrile derivatives consisting of methoxy group and alkoxy chain with different lengths were synthesized and their gelation abilities were investigated. It was found that compounds with longer alkoxy chains and a nitro group could gelate some nonpolar and polar organic solvents. On the other hand, diphenylacrylonitrile derivatives without nitro group could not form gels in measured solvents, suggesting that the electron-withdrawing nitro moiety plays an important role in the gel formation. X-ray diffraction showed that gelator molecules stacked together with lamellar packing structures in the gel phases. More importantly, the gelators emitted very weak fluorescence in the solutions because of the twisted conformation in the isolated state. However, the gels had strong fluorescence owing to the suppression of molecular motion, molecular planarization and J-aggregate formation, implying gelation-induced emission enhancement.

In Situ Formation of Dual‐Phase Thermosensitive Ultrasmall Gold Nanoparticles

A novel method for the in situ synthesis of dual-phase thermosensitive ultrasmall gold nanoparticles (USGNPs) with diameters in the range of 1-3 nm was developed by using poly(N-isopropylacrylamide)-block-poly(N-phenylethylenediamine methacrylamide) (PNIPAM-b-PNPEDMA) amphiphilic diblock copolymers as ligands. The PNPEDMA block promotes the in situ reduction of gold precursors to zero-valent gold and subsequently binds to the surface of gold nanoparticles, while PNIPAM acts as a stabilizing and thermosensitive block. The as-synthesized USGNPs stabilized by a thermosensitive PNIPAM layer exhibit a sharp, reversible, clear-opaque transition in aqueous solution between 30 and 38 °C. An unprecedented finding is that these USGNPs also show a reversible soluble-precipitate transition in nonpolar organic solvents such as chloroform at around 0 °C under acidic conditions.

Synthesis and self-aggregation of chlorophyll derivatives possessing a pyrazole ring at the C3 position

Abstract Chlorophyll compounds possessing an N-(un)substituted pyrazole ring at the C3 position were synthesized by the reaction of chlorophyll-a derivative having a trifluoromethyl-β-diketonate group with (substituted) hydrazines in 2,2,2-trifluoroethanol through the pyrazoline ring. The substituents on the C3-heterocyclic 5-membered ring affected the electronic absorption and emission of the monomeric chlorin molecules. Vis, CD and 1H NMR spectra of the zinc chlorin bearing an N-unsubstituted pyrazole showed its dimerization in a nonpolar organic solvent.