Nonpolar Organic Solvents Research Articles

Adsorption and Rheology of Graphitic Carbon Black Nonaqueous Dispersions Prepared Using Nonionic Surfactants

Rheological and conductivity measurements are reported to investigate the dispersibility of graphitic carbon black dispersions selected as a model for carbon nanotubes. The effectiveness of three dispersants in nonpolar organic solvents were investigated namely polyhydroxystearic acid (Hypermer LP1), PEG 30-dipolyhydroxystearate (Hypermer B246), and polyisobutylene succinimide (OLOA 11000). Hypermer LP1 is homopolymer and Hypermer B246 is polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer while OLOA 11000 has polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Two nonpolar organic solvents decalin and xylene were selected for the present work. The experimentally determined relative viscosity as a function of effective volume fraction Φ′ curves were compared with the theoretical curves calculated using Kreiger-Dougherty equation for the hard sphere dispersions. The comparison showed that Hypermer B246 and OLOA 11000 dispersions in xylene could be prepared at somewhat higher solid fraction than those dispersions stabilized by Hypermer LP1. Also Hypermer LP1 dispersions do not agree with the Kreiger-Dougherty equation curve, which showed that Hypermer LP1 is not an effective stabilizer. In oscillatory measurements, high values of storage and loss modulus at high volume fractions were obtained indicating strong repulsive interactions between the carbon black particles using Hypermer B246 and OLOA 11000. The dispersions prepared using these surfactants showed lower electrical conductivity as compared to other dispersions prepared without dispersants. Also higher relative conductance was obtained in case of dispersions made by Hypermer LP1 as compared to other dispersions made by Hypermer B246 and OLOA 11000.

The Role of Organic Solvents and Conformational Behavior of Nematogens Having trans Extended Conformation – A Computational Approach

The role of organic solvents on nematogenic p-n-alkoxy cinamic acids (nOCAC) with alkyl chain carbon atoms (n = 6, 8) has been reported with respect to the translational and orientational motions. The atomic net charge and dipole moment components at each atomic center have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh–Schrodinger perturbation theory with the multicentered–multipole expansion method has been employed to evaluate the long-range interactions, and a “6-exp.” Potential function has been assumed for the short-range interactions. The minimum energy configurations obtained during the different modes of interactions have been taken as input to calculate the configurational probability using the Maxwell–Boltzmann formula in nonpolar organic solvents, that is, carbon tetrachloride, and chloroform at room temperature (300 K). It has been observed that the molecules show the remarkable behavior in the solvents. A comparison of stacked dimers between both the molecules suggests that the extension of the chain length to eight carbon atoms, a recognizable segregation of dimers into a highly tilted layer structured has been obtained.

Thermally cross‐linkable copolymer and its evaluation as a hole transport layer in organic light‐emitting diode devices

AbstractThis study reports on the synthesis of new thermally cross‐linkable copolymers containing a reactive cross‐linking comonomer. Synthesized polymers showed narrow molecular weight distribution (polydispersity) between 1.18 to 1.22 and 54 to 67% monomer conversion and incorporation of 2 to 7 mol% vinylbenzylcyclobutene comonomer. The polymer was soluble in nonpolar organic solvents such as chloroform, dichloromethane, toluene, and chlorobenzenes, and when cross‐linked, showed resistance to solubility in the previously listed solvents. The cross‐linked films exhibited uniform surface roughness below 1 nm. A polymer containing ~3.6 mol% vinylbenzylcyclobutene was thermally cross‐linked and evaluated as a hole‐transporting layer in green organic light‐emitting diode devices. The devices showed a maximum current efficiency of 39.5 cd/A at a current density of 2.7 mA/cm2 and a brightness of 1000 cd/m2 with an International Commission on Illumination coordinate (0.33, 0.62). The device performances are found comparable with the ones with the conventional hole‐transporting layer material, NPD.

True water soluble palladium-catalyzed Heck reactions in aqueous–organic biphasic media

A stable water soluble palladium catalyst has been demonstrated for the Heck reaction in a biphasic medium (water–non-polar organic solvent). Biphasic Heck reactions reported till now generally employ a non-polar solvent along with an aqueous polar water miscible organic solvent as the second phase. The efficiency of the Pd complex of TOTPS [Trisodium salt of tri-(ortho-tolyl) phosphine tri sulfonate] for the vinylation of different aryl iodides and olefins is demonstrated. The advantages of a co-solvent for this biphasic system have also been shown. The catalyst has been recycled efficiently retaining the activity with negligible loss of catalyst and without leaching of the Pd.

Filterable Redox Cycling Activity: A Comparison between Diesel Exhaust Particles and Secondary Organic Aerosol Constituents

The redox activity of diesel exhaust particles (DEP) collected from a light-duty diesel passenger car engine was examined using the dithiothreitol (DTT) assay. DEP was highly redox-active, causing DTT to decay at a rate of 23-61 pmol min(-1) μg(-1) of particle used in the assay, which was an order of magnitude higher than ambient coarse and fine particulate matter (PM) collected from downtown Toronto. Only 2-11% of the redox activity was in the water-soluble portion, while the remainder occurred at the black carbon surface. This is in contrast to redox-active secondary organic aerosol constituents, in which upward of 90% of the activity occurs in the water-soluble fraction. The redox activity of DEP is not extractable by moderately polar (methanol) and nonpolar (dichloromethane) organic solvents, and is hypothesized to arise from redox-active moieties contiguous with the black carbon portion of the particles. These measurements illustrate that "Filterable Redox Cycling Activity" may therefore be useful to distinguish black carbon-based oxidative capacity from water-soluble organic-based activity. The difference in chemical environment leading to redox activity highlights the need to further examine the relationship between activity in the DTT assay and toxicology measurements across particles of different origins and composition.

Synthesis and self-assembly of amphiphilic zinc chlorophyll derivatives possessing a crown ether at the 17-propionate residue

Zinc 31-hydroxy-131-oxo-chlorins 1–3 possessing a 12-crown-4, 15-crown-5, and 18-crown-6 ether at the 17-propionate residue were synthesized and self-assembled in aqueous and non-polar organic media. Zn chlorins 1–3 exhibited red-shifted Qy absorption bands and large CD signals around 730 nm in an aqueous solution after standing for 2 h or 2 days, indicating the formation of their oligomeric self-aggregates as in chlorosomes of green photosynthetic bacteria. Incubation for 2 weeks decreased the absorption bands around 730 nm, accompanying an appearance of the absorption band around 675 nm. These show that Zn chlorins 1–3 finally formed thermodynamically stable anti-parallel dimers in the aqueous solution. 176-Epimerically pure 1–3 exhibited essentially the same spectral properties as the corresponding epimeric mixtures, but larger CD signals were observed around 730 nm in the spectra of epimerically pure 1 and 2 after standing for 2 h or 2 days than those of their epimeric mixtures. In a non-polar organic solvent, Zn chlorins 1–3 formed less time-dependent chlorosomal self-aggregates that exhibited Qy absorption bands around 735 nm.

Spectral properties of coumarin derivatives in various environments

Abstract The structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment

Fluctuated atom-sized junctions in a liquid environment

Durability of atom-sized junctions in a liquid environment was investigated and compared with that in a vacuum. The single atom junction lifetime was measured in an organic solvent under various stretching speed vd ranging from 10 to 0.001 nm/s. We found the natural lifetime of about 1 s for Au single-atom chains formed in a non-polar organic solvent at vd ≤ 0.01 nm/s, which was an order of magnitude shorter than that in a vacuum. The decreased junction lifetime indicates contact instability induced by thermal collisions of solvent molecules that exert pressure on the nanocontacts.

Growth mechanism of Ag2S nanocrystals in a nonpolar organic solvent

Understanding the growth process of nanomaterials enables the control of their sizes/morphologies to enhance their performance for a given application. Herein we report the investigation into the synthesis of Ag2S nanocrystals by reacting Ag+ ions and/or Ag nanoparticles with S powder in a nonpolar organic solvent. The results show that the growth of Ag2S nanocrystals follows a “coalescence–fracture–ripening” mechanism, which is different from the commonly accepted LaMer nucleation growth model. At the initial stage of the reaction, Ag2S nanoclusters are formed on the surface of massive S powders and then coalesce to form extensive network of nanowires, which later are hollowed and fragmented into quasi-spherical particles due to the inside-out diffusion of S in nanowires. The quasi-spherical particles finally grow into uniform Ag2S nanocrystals through a ripening process. It has been found that the Ag2S growth process can be greatly accelerated by increasing the temperature of the reaction system and the sizes/morphologies of the final Ag2S nanocrystals can be easily tuned by varying the molar ratio of the starting precursors.

Immobilization of Cauliflower Myrosinase on Agar Agar Matrix and its Application with Various Effectors

The purified and thermo stable myrosinase from cauliflower seedlings was immobilized by 3.5% agar agar matrix and immobilized myrosinase chips were stored in extraction buffer. After 48 hours 30% enzyme activity was exuded into extraction media from immobilized enzyme chips. Effect of some metal ions and organic solvents on the activity of immobilized cauliflower myrosinase was studied. Amongst selective metal ions (Sr2+, Sn2+ and Ba2+), Sr2+ at 4 mM concentration exhibited marked activating effect on the activity up to 3 fold. However, Sn2+ and Ba2+ increased the activity to a certain extent and then suppressed. Activation kinetics of myrosinase in presence of Sn2+ and Sr2+ were studied between 0-20min.The rate of reaction was almost constant till 15 min and then slight deactivation was recorded at various concentrations used. On the other hand, few heavy metal ions [Fe2+, Fe3+, Cu2+ and Zn2+] strongly inhibited the activity even at lower concentrations. Several nonpolar organic solvents even at comparatively higher concentrations had detectable activation effects. Further, their activity was seen with respect totime (27 min). However, some protic polar organic solvents exhibited inhibitory effect with immobilized myrosinase except to butanol.

The Remarkable Effect of Solvents on Smectogen Having a V-Shaped Conformation – A Computational Model

The effect of solvents on a smectogen, N-n-undecyl-D-gluconamide, having a V-shaped conformation has been carried out with respect to translational and orientational motions. The complete neglect differential overlap method has been employed to compute the net atomic charge and atomic dipole moment components at each atomic center. The modified Rayleigh–Schrodinger perturbation theory along with the multicentered–multipole expansion method has been employed to evaluate the long-range intermolecular interactions, while a “6-exp” potential function has been assumed for short-range interactions. The total interaction energy values obtained through these computations have been used as input to calculate configurational probability in non-polar organic solvents, i.e., carbon tetrachloride (CCl4) and chloroform (CHCl3) using the Maxwell–Boltzmann formula at room temperature (300 K). It has been observed that the molecule produce remarkable property in the solvents. Further, an attempt has been made to develop a new and interesting model for smectogen at molecular level.

The growth of metal sulfide–Au/Ag nanocomposites in a nonpolar organic solvent

The combination of two or more chemically distinct components in one single nanostructure will undoubtedly lead to useful applications of nanomaterials in various areas. Herein, we report our experimental observations on composite nanosystems consisting of metal sulfide and Au and/or Ag noble metals. A number of characterization techniques, including transmission electron microscopy (TEM), high-resolution TEM (HRTEM), high-angle annular dark-field scanning TEM (HAADF-STEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) are used to characterize the morphology of the formed nanocomposites, and to address the following critical issues: i) the deposition behavior of the noble metals on the semiconductor nanocrystals; ii) the relationship between the morphology of the nanocomposites and the structure of the semiconductors; and iii) the mechanism accounting for the morphology formation of the final composite nanoparticles.

The Influence of Organic Solvents and Conformational Behavior of Mesogenic Compounds: A Computational Approach

The role of organic solvents and conformational behavior of liquid crystalline disubstituted biphenylcyclohexanes (BCHs) of the general formula R-C6H10-C6H4-C6H4-X with R: C3H7; X: H (BCH30) and R: C5H11; X: CN (BCH5CN) have been reported with respect to the translational and orientational motions. The atomic net charge and dipole moment components at each atomic center have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh-Schrodinger Perturbation theory with the multicentered–multipole expansion method has been employed to evaluate the long-range interactions, and a “6-exp.” potential function has been assumed for the short-range interactions. The minimum energy configurations obtained during the different modes of interactions have been taken as input to calculate the configurational probability using the Maxwell-Boltzmann formula in non-polar organic solvents, i.e., carbon tetrachloride (CCl4) and chloroform (CHCl3), at room temperature 300 K. It has been observed that the molecules show the remarkable behavior in the solvents. A comparison of stacked dimers between both the molecules suggests that the extension of the chain length, a recognizable segregation of dimers into a highly tilted layer structured, has been obtained for BCH5CN molecule.

Simple and rapid removal of the interference in gangliosides extracted from HPTLC spot on MALDI-TOF MS analysis

Extraction of thin-layer chromatography (TLC) spot with organic solvents is one of the convenient methods for glycolipid isolation from crude samples, but other background contaminants are also co-extracted during this process. Calcium sulfate (gypsum), starch and synthetic polymers are commonly used as binders in TLC plates, and the co-extracted synthetic polymers usually interfere with further structural analyses, especially in analysis by mass spectrometry (MS). Several column chromatographic processes are therefore used to purify these extracts. However, the purification processes are time consuming and suffer from sample loss. In our previous study, we established a method for detergent removal from glycolipids in a detergent-resistant membrane microdomain (DRM). The procedure is based on selective detergent extraction, in which the sample is dried in a glass tube, followed by washing with non-polar organic solvents, 1,2-dichloroethane (DCE). In this study, we have attempted to apply this method for the background removal from gangliosides and glycosylinositolphosphoceramides extracted from high performance TLC (HPTLC) spots. After DCE washing, these glycolipids were detected by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, and it was found that DCE washing could effectively remove HPTLC backgrounds.

Reverse self-assembly of lipid onions induced by gadolinium and calcium ions

Self-assembly of lipids in water is well-known to result in nanostructures such as vesicles in dilute solution. In contrast, self-assembly in nonpolar organic solvents (oils) is much less established and there are hardly any known routes to forming structures such as reverse vesicles. Here, we build such structures based on our surprising recent discovery that salts can influence self-assembly of lipids in oil. We induce the self-assembly of nanoscale multilamellar vesicles (“onions”) in cyclohexane and toluene by combining the saturated phospholipid, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), with salts of di- or trivalent cations like calcium (Ca2+) or gadolinium (Gd3+) in the absence of water. DMPC–Gd3+ onions can be seen by a transmission electron microscope (TEM) without additional staining. They have sizes between ∼100 and 400 nm and have 6–18 concentric bilayer shells (lamellae) that are uniformly spaced. The presence of lamellae is further confirmed by small-angle X-ray scattering (SAXS), from which we find the inter-lamellar spacing to be 6.0 nm. The formation of reverse onions is driven by the binding of these multivalent cations with the lipid headgroups, which in turn brings adjacent lipids close and causes a tighter packing of the lipid tails. Evidence for such binding is provided by the cation-induced lowering of the lipid melting temperature.

Quick and selective synthesis of Li6[α-P2W18O62]·28H2O soluble in various organic solvents

Herein we report the synthesis of α-Dawson type POM, Li6[α-P2W18O62]·28H2O, directly from the use of Li2WO4 as the tungstate source. The salt obtained was soluble not only in water but also in a range of polar and non-polar organic solvents, such as benzene.

Bismuth sulphide–polymer nanocomposites from a highly soluble bismuth xanthate precursor

Bismuth sulphide nanocrystal–polymer hybrid layers are of interest for various optoelectronic, thermoelectric or sensing applications. In this work, we present a ligand-free in situ route for the formation of Bi2S3 nanorods directly within a polymer matrix. For this purpose, we introduce a novel bismuth xanthate (bismuth(III) O-3,3-dimethylbutan-2-yl dithiocarbonate), which is highly soluble in non-polar organic solvents. The analysis of the crystal structure revealed that the prepared bismuth xanthate crystallises in the monoclinic space group C2/c and forms dimers. The bismuth xanthate can be converted into nanocrystalline Bi2S3 with an orthorhombic crystal structure via a thermally induced solid state reaction at moderate temperatures below 200 °C. In combination with the high solubility in non-polar solvents this synthetic route for Bi2S3 is of particular interest for the preparation of Bi2S3–polymer nanocomposites as exemplarily investigated on Bi2S3–poly(methyl methacrylate) and Bi2S3–poly(3-hexylthiophene-2,5-diyl) (P3HT) nanocomposite layers. Atomic force and transmission electron microscopy revealed that Bi2S3 nanorods are dispersed in the polymer matrix. Photoluminescence experiments showed a quenching of the P3HT fluorescence with increasing Bi2S3 content in the hybrid layer.

Monodisperse transfer of superparamagnetic nanoparticles from non-polar solvent to aqueous phase

The use of superparamagnetic nanocrystals (MNPs) for biomedical applications generally requires a synthetic route in which the resultant MNPs are water soluble and biocompatible with good morphology and size distribution control, as well as optimized hydrodynamic size. To achieve this, hydrophobic MNPs are typically synthesized through the thermolysis process and thereafter water solubilized by using amphiphilic brush co-polymers. In this paper, two types of MNPs were synthesized, i.e. magnetite and manganese ferrite nanocrystals. We presented the optimization process of a water solubilization route by employing poly(isobutylene-alt-maleic anhydride) grafted with dodecylamine (PIMA-g-C12) as the coating. Several parameters that would lead to monodisperse phase transfer of the superparamagnetic nanocrystals (i.e. minimization of the overall MNPs hydrodynamic size) were investigated. These included the PIMA-g-C12/MNPs ratio, the amount of hydrolyzing agent and the initial MNPs concentration in non-polar organic solvent. Such PIMA-g-C12 coated MNPs were found to exhibit good colloidal stability (pH, temperature and kinetic stability). Lastly, PIMA-g-C12 coated MNPs also exhibited excellent in vitro biocompatibility when incubated with NIH/3T3 fibroblast and MCF-7 breast cancer cells.

Concentrated colloidal dispersion of decanoic acid self-assembled monolayer protected CeO2 nanoparticles up to 77 wt% in nonpolar organic solvents

ABSTRACTSelf-assembled monolayers (SAMs) of decanoic acids were prepared on cerium oxide nanoparticles (NPs). The dispersion of the NPs was improved by increasing the packing density of decanoic acid SAM on the NPs. Highly concentrated ceria nanofluids more than 22 vol% (about 77 wt%) in cyclohexane and trans-decalin were achieved, according to the criterion to the packing density and chain length of the alkanoic acid of the SAM to disperse the ceria NPs in nonpolar organic solvents proposed previously. Temperature effect on the dispersion was also examined and it was turned out that the dispersion was strongly enhanced with activation of Brownian motion.

Rapid and sensitive determination of acrylamide in potato crisps using reversed-phase direct immersion single drop microextraction-gas chromatography

A new, simple and rapid approach using reversed-phase direct immersion single drop microextraction (RP-DISDME) was established for the determination of acrylamide at low levels in potato crisps samples. In conventional SDME, the extracting phase is a micro-drop of a non-polar organic solvent that cannot extract acrylamide due to its polarity. In the developed RP-DISDME method, this problem was overcome by replacing the organic solvent with a micro-droplet of water. The influence of extraction parameters such as extraction temperature and time, stirring rate, drop volume and pH were controlled and optimized. The developed protocol was found to yield a linear calibration curve in the concentration range from 0.1–1000 mg L−1 with a limit of detection of 57 μg kg−1 with a good enrichment factor of 136 for the analyte. The repeatability of the method was satisfactory (RSD ≤ 6.26%). Total analysis time including microextraction and gas chromatography analysis was less than 20 min. Recovery of the method was found to be better them 91.9%.