Chloroform System Research Articles

Chiroptical generation and amplification of hyperbranched π-conjugated polymers in aggregation states driven by limonene chirality

In this contribution, a series of hyperbranched π-conjugated poly(9,9-di-n-octylfluorene)s (HPF8s) with hexaoctyltruxene (HT) as branching units were successfully prepared by a Suzuki polycondensation reaction. We present the first generation of optically active HPF8s in aggregation states with strong circular dichroism (CD) and circularly polarised luminescence (CPL) properties. The optically active aggregates of HPF8s were efficiently produced by CD-/CPL-silent HPF8s with the help of solvent chirality transfer from chiral limonene at room temperature. The emergence of CD and CPL signals of HPF8s aggregates results from the weak forces (π/π, van der Waals, CH/π and OH/π interactions) in a tersolvent system of chloroform (a good solvent), alkanol (a poor solvent), and (R)-(+)-/(S)-(−)-limonene (1R/1S, a chiral source). The hyperbranched polymer structure (degree of branching), poor solvent type, volume fraction of methanol and 1R/1S, limonene enantiopurity and polymer concentration have obvious effects on the magnitude and sign of the CD signals. The obtained HPF8s aggregates have relatively strong UV-vis absorption and CD signals in the range of 300–500 nm as well as CPL emission (420–460 nm) under optimised conditions. The current study will open up a new avenue for efficiently producing ambidextrous chiroptical hyperbranched polymeric materials without any specific chiral catalysts or substituents under mild conditions.

Solvent micro-evaporation and concentration gradient synergistically induced crystallization of poly(l-lactide) and ring banded supra-structures with radial periodic variation of thickness

The crystalline morphology and structure of poly(L-lactide) (PLLA) in a PLLA film–chloroform system were investigated by means of wide angle X-ray diffraction (WAXD), polarized optical microscopy (POM) and atomic force microscopy (AFM). Birefringent and nonbirefringent ring banded supra-structures with radial periodic variation of thickness were obtained, which were induced by micro-evaporation of solvents and concentration gradient of PLLA. The ring banded morphologies consisted of multilayer lamellar crystals, which is a manifestation of alternating ridge and valley bands of periodic variation of thicknesses along the radial direction. The formation of the ring banded supra-structures is associated with diffusion and crystal growth induced periodic variation of concentration gradient, which is attributed to diffusion-related rhythmic growth and the competition between diffusion of polymer segments and growth of crystal lamellae. The mechanism of such banded-ring formation was explored on the basis of rhythmic growth resulting from non-linear diffusion.

Diffusivity data and reaction kinetics as probes for self-assembling: Cationic surfactant–chloroform system

Herein two sensitive techniques, i.e., NMR self-diffusion measurements and dielcometry are involved to test the association of cationic surfactant 4-aza-1-tetradecyl-1-azoniabicyclo[2.2.2]octane bromide (BC-14) and polyethyleneimine hydrophobized with tetradecyl moieties (PEI-14) in their chloroform solutions. The data obtained make it possible to nominate these methods as highly powerful instruments for the identification of a very uncooperative aggregation. Mixed BC-14/PEI-14 association is probably observed only at a relatively high polymer concentration, which is indicated by a decrease in the diffusivity of surfactant molecules. Aggregation is strongly promoted by the addition of water, with a high [water]/[BC-14] molar ratio of 60 attained. Even a very slight association has a serious impact on the reactivity, the pre-concentration effect and the shift of acid–base equilibrium of solutes. A 4-fold acceleration of the reactivity of an organophosphorus pollutant occurs in the BC-14 reverse micelles due to the concentration of reagents and changes in their microenvironment, which strongly supports the very idea of association. The high binding constants derived from the analysis of kinetic data provide evidence on high degree of concentration of compounds, while changes in the microenvironment affect their ionization. These impacts may be of key importance in analytical procedures and the chemical reactivity of compounds in nonpolar media.

Viscometric Analysis of Miscibility and Interactions for Binary, Ternary Polycarbonate/Brominated Polystyrene + Chloroform Systems at Different Temperatures

Viscosities of ternary systems consist of polycarbonate (PC)/brominated polystyrene (PBrS) in chloroform and their corresponding binary systems were measured at different temperatures (20, 25, and 30°C). All the measurements were carried out at the concentration ranges of 0.1–0.6 g·dL−1. The mass ratio of PC to PBrS was selected as 75:25, 50:50, and 25:75 in the ternary solutions. Two empirical expressions of Huggins and Kraemer equations with three-parameters were used for reproducing of the experimental viscosity data. The fitting parameters were obtained for the corresponding temperatures. The miscibility criteria on the basis of the sign of Δ[η]m based on the difference between experimental and ideal values of [η]m, was calculated by applying the Garcia et al., theoretical equation. The effect of temperature on the viscosity data was also studied. The results from this method were correlated with the miscibility data obtained for the same system by differential scanning calorimeter (DSC) findings.

The choice of solvent and liquid–liquid equilibrium for ternary water + 2-methylaziridine + chloroform system: Experimental data and modeling

Based on solvent selection criteria, chloroform was introduced as the most appropriate solvent for the extraction of 2-methylaziridine from aqueous phase. Accordingly, liquid–liquid equilibrium (LLE) data for the ternary water+2-methylaziridine+chloroform system were obtained at different temperatures of 288.2, 298.2 and 313.2K and under ambient pressure. The data for equilibrium composition were determined by cloud point method and conjugate points on tie lines were obtained using the refractive index as a function of composition. Results showed that relative mutual solubility of 2-methylaziridine was higher in aqueous phase than organic phase, and tie line data at each temperature were nicely agree with the Othmer–Tobias correlation. Consequently, extraction capability of chloroform was evaluated with respect to distribution coefficient and separation factor. The NRTL and UNIQUAC models were used to correlate the experimental data and both models showed satisfactorily agreement; however, NRTL exhibited better agreement.

Metal ion removal by ultrafiltration of colloidal suspensions of organically modified silica

Porous fumed silicas (FS) covalently grafted with 5-phenyl-azo-8-hydroxyquinoline (5Ph8HQ) are considered as extractants for copper(II) and nickel(II) at low concentration levels (10–50μM). The separation of the extracting colloidal functionalized silicas particles from the bulk aqueous phase is achieved by means of the frontal ultrafiltration technique. The stability of the colloidal dispersion of the organically modified silica and of the covalent grafting itself is studied via the loss of silica or of 5Ph8HQ through the ultrafiltration membrane during the separation process. The effects of the anion nature, specific surface area, surface ionization state on the metal ions extraction are assessed. For the sake of comparison, the extraction of copper(II) by 5Ph8HQ solubilized in neutral Triton X-100 (TX-100) micelles has been studied in the most similar experimental conditions, as well as copper(II) extraction by the same ligand in a biphasic water–chloroform system. High copper extraction yields are attained, and taking into account the low volume of extracting phase of the dispersed colloidal silica, high separation factors are obtained. The stoichiometry of the formed complex is the same (1:1) in the two microheterogeneous systems considered here whereas a 2:1 complex is formed in the biphasic liquid–liquid system. The apparent stability constant is greater by a factor 10 in the micelles than for the silica bounded 5Ph8HQ systems but the true affinity of the ligand for copper is 5 times lower in the micelle than on the functionalized systems. Comparing to the literature, it is shown that the type of silica considered (colloidal fumed silica in this work versus silica gel in the literature) greatly influences the affinity of the ligand toward the copper. Finally, the apparent extraction constant in 5Ph8HQ modified silica is ten times higher for copper(II) than for nickel(II).

Specific Cooperative Effect of a Macrocyclic Receptor for Metal Ion Transfer into an Ionic Liquid

An intramolecular cooperative extraction system for the removal of strontium cations (Sr(2+)) from water by use of a novel macrocyclic receptor (H(2)βDA18C6) composed of diaza-18-crown-6 and two β-diketone fragments in ionic liquid (IL) is reported, together with X-ray spectroscopic characterization of the resulting extracted complexes in the IL and chloroform phases. The covalent attachment of two β-diketone fragments to a diazacrown ether resulted in a cooperative interaction within the receptor for Sr(2+) transfer, which remarkably enhanced the efficiency of Sr(2+) transfer relative to a mixed β-diketone and diazacrown system. The intramolecular cooperative effect was observed only in the IL extraction system, providing a 500-fold increase in extraction performance for Sr(2+) over chloroform. Slope analysis and potentiometric titration confirmed that identical extraction mechanisms operated in both the IL and chloroform systems. Extended X-ray absorption fine structure spectroscopy revealed that the average distance between Sr(2+) and O atoms in the Sr(2+) complex was shorter in IL than in chloroform. Consequently, Sr(2+) was held by H(2)βDA18C6 more rigidly in IL than in chloroform, representing an important factor dominating the magnitude of the intramolecular cooperative effect of H(2)βDA18C6 for Sr(2+). Furthermore, competitive extraction studies with alkaline earth metal ions revealed that the magnitude of the intramolecular cooperative effect depended on the suitability between metal ion size and the cavity size of H(2)βDA18C6. Sr(2+) was successfully recovered from IL by controlling the pH in the receiving phase, and the extraction performance of H(2)βDA18C6 in IL was maintained after five repeated uses.

Phase-Transfer Behavior of Cross-Linked Poly(acrylic acid) Particles Prepared by Dispersion Polymerization from Ionic Liquid to Water

The phase-transfer behavior of poly(acrylic acid) (PAA) particles from the hydrophobic ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)amide phase to the water phase in the particle state, which we reported previously, was examined in more detail. PAA particles were prepared in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([Bmim][TFSA]) and the organic solvent chloroform and were extracted. The transfer of PAA particles to water in the particle state was also observed in [Bmim][TFSA] systems. In contrast, the transfer phenomenon was not observed in the chloroform system. It was clarified that water/oil interfacial tension γ(wo) is an important parameter in the extraction of PAA in the particle state from the viewpoint of free energy. When the cationic surfactant tetradecyltrimethylammonium bromide, aqueous solution was used as the extraction medium, the PAA particles were extracted in the particle state from chloroform to water, in which γ(wo) became as low as that of the ionic liquid. This suggests that the phase-transfer phenomenon of PAA particles in the particle state was induced by the ionic liquid's unique property of low interfacial tension with water despite its high hydrophobic character.

Role of diluent on the separation of 90Y from 90Sr by solvent extraction and supported liquid membrane using T2EHDGA as the extractant

The separation behaviour of (90)Y from (90)Sr was investigated by diluent variation using solvent extraction and supported liquid membrane techniques employing N,N,N',N'-tetra-2-ethylhexyldiglycolamide (T2EHDGA) as the extractant. Both D(Y) (distribution ratio of Y(III)) and S.F. (separation factor) were found to be high in the solvent extraction studies when chloroform was used as the diluent. Subsequent supported liquid membrane (SLM) studies using PTFE flat sheet membranes containing 0.2M T2EHDGA in various diluents indicated the trend of Y transport as xylene>hexone>chloroform>carbon tetrachloride>n-dodecane+30% iso-decanol mixture. However, the Sr(II) transport rates were also high with xylene, hexone, and carbon tetrachloride as the diluents which led us to carry out subsequent studies using chloroform and n-dodecane+30% iso-decanol mixture. Acid variation studies in chloroform system indicated an interesting phenomena of increasing Y(III) transport and decreasing Sr(II) transport with increasing acid concentration. Separation of (90)Y from a mixture of (90)Sr and (90)Y was also attempted.

Aggregation of bis(N-octanoylaminocarboxylato) magnesium(II) complexes in water/organic solvents

Abstracts The aggregation of magnesium(II) complex surfactants of bis( N -octanoylalaninato) (= Mg(oct-ala) 2 ) and bis( N -octanoylphenylalaninato) (= Mg(oct-phe) 2 ) in water/organic solvent (= chloroform, 1-hexanol, and cyclohexanol) mixtures and the effect of water on the aggregation behavior were studied using electric conductivity, NMR spectroscopy, and viscosity. Because of the moderate hydrophile–lipophile balance, Mg(oct-ala) 2 and Mg(oct-phe) 2 form aggregates in hydrophobic organic solvents by encapsulating water which assists the dissolution and aggregation of the metal complexes. A change in the structure from a reverse micelle to an onset of bicontinuous microemulsion in water/1-hexanol or water/cyclohexanol mixed solvent was detected with an increase in the water content. The strong ionic interaction between the magnesium ion and the ligand was reflected in the characteristic aggregation behavior of the magnesium surfactants. Correlation times of the hydration water bound to the metal-complex aggregates in wet chloroform system were determined by the measurements of 2 H 2 O longitudinal relaxation times.

In vitro antimicrobial activity of Muntingia calabura extracts and fractions

The aim of the present study is to determine the in vitro antimicrobial activity of various extracts, partitions and fractions of Muntingia calabura (Elaeocarpaceae) leaves against a selected panel of microorganisms. The leaves of M. calabura were soaked separately in the aqueous, chloroform and methanol solvent systems in the ratio of 1:20 (w/v) for 72 h and these procedures were repeated three times. Antimicrobial testing was carried out using the micro-broth dilution method. The microbes targeted were Staphylococcus aureus 25923, S. aureus 33591 (a multi-drugs resistant S. aureus (MRSA) isolate), Escherichia coli 35218, Pseudomonasaeruginosa ATCC 27853, Candida albicans 10231 and Microsporum canis ATCC 36299. The methanol extract inhibited MSSA (MIC = 1250 µg/ml; MBC = 1250 µg/ml) and MRSA (MIC = 1250 µg/ml; MBC = 1250 µg /ml) and considered the most effective extract and was further partitioned sequentially using the aqueous, petroleum ether and ethyl acetate. The ethyl acetate partition exhibited effective antibacterial activities with the MIC/MBC value of 156 and 313 µg/ml against S. aureus 25923 and S. aureus 33591, respectively. The ethyl acetate partition underwent fractionation process and yielded 15 fractions (A1-A15) of which only fractions A9 to A15 effectively inhibited the growth of S. aureus 25923 and S. aureus33591 with MIC/MBC values ranging from 78 to 2500 µg/ml. Key words: Muntingia calabura, Elaeocarpaceae, antimicrobial activity, micro-broth dilution, ethyl acetate fraction.

Synthesis and properties of 5,10,15,20-tetrakis[4-(alkoxysilyl)phenyl]porphyrins: an application of selective deprotection of benzaldehyde diethyl acetals in the presence of alkoxysilyl groups

Selective deprotection of 4-(alkoxysilyl)benzaldehyde diethyl acetals 1a-1c in the two-solvent system of hydrochloric acid and chloroform gave 4-(alkoxysilyl)benzaldehydes 2a-2c in good yields. Under these conditions, undesired hydrolysis of the alkoxysilyl group was minimized. The reaction of benzaldehydes 2a and 2b with pyrrole in the presence of boron trifluoride diethyl etherate led to 5,10,15,20-tetrakis[4-(alkoxysilyl)phenyl]porphyrins 3a and 3b. The X-ray structural analysis showed that 3b has a planar porphyrin ring and shows typical structural features of porphyrin rings. Hydrolysis-condensation of 3a in the presence of a surfactant afforded a porphyrin-silica hybrid (PSH) as insoluble brown powder. The PSH was found to be amorphous and to consist of aggregated nonspherical micrometre-sized particles with rough surfaces. The PSH has mesopores, and the specific surface area is 330 m(2) g(-1) which increases to 810 m(2) g(-1) upon calcination.

Ultrathin Pt-Based Alloy Nanowire Networks: Synthesized by CTAB Assistant Two-Phase Water−Chloroform Micelles

Ultrathin Pt-based PtM (M = Pd, Ru, Au, Fe) alloy nanowire networks could be facilely synthesized using a soft template formed by cetyltrimethylammonium bromide in a two-phase water−chloroform system. The as-synthesized Pt-based alloyed nanowires show the fcc crystal phase. They have an average diameter of ∼2.3 nm and form porous nanonetworks, which can be potentially used for a number of catalytic applications. It was found that PtRu alloy nanonetworks showed more efficient catalytic activity for the hydrogenation of azo bonds in methyl orange than that of PtPd, PtAu, and pure Pt.

Device Performance and Polymer Layer Morphology in Polymer Bistable Device (PBD): The Control of Physicochemical Properties of Solvent

The surface morphology control of poly(N-vinyl carbazole) (PVK) layer for the improvement of polymer bistable devices (PBDs) performance was investigated based on the simultaneous consideration of the compatibility of polymer with solvent and the polymer ordering behavior during the solvent evaporation by introducing the bisolvent system of chloroform and 1,1,2,2-tetrachloro-ethane (TCE). It was confirmed by ultra violet (UV)-vis spectroscopy that PVK has significantly higher compatibility with chloroform than TCE. On the other hand, atomic force microscope (AFM) revealed that the chloroform/TCE = 9/1 bisolvent led to the improved film morphology (the surface roughness of 0.190 nm) than chloroform, because the presence of TCE representing slower evaporation rate contributed to the enhancement of PVK ordering and arrangement during the solvent evaporation for the film formation. The great correlation was made between the film morphology properties and I-V characteristics of PBDs. The PBDs with PVK layer cast from the chloroform/TCE = 9/1 bisolvent showed dramatically improved bistability characteristics (Vth approximately equal to 2 V and Ion/Ioff ratio > 10(3)).

Comparison of solid dispersions produced by supercritical antisolvent and spray-freezing technologies

Oxeglitazar is a new orally administered poorly water soluble active substance used in the treatment of type II diabetes. The objective of this work was to improve its dissolution kinetics using supercritical antisolvent (SAS) and spray-freezing (SF) techniques. Oxeglitazar was formulated with various excipients, including: Poloxamer 188 and 407, polyethylene glycol (PEG) 8000 and polyvinilpyrrolidone (PVP) K17 in a 1:1 weight ratio. In the SAS technology, pharmaceutical ingredients were dissolved in an appropriate solvent, and the feed solution was dispersed through a capillary nozzle in supercritical CO 2 (SC CO 2). Dichloromethane (DCM), chloroform (CHCl 3), and a binary co-solvent system of chloroform–ethanol (EtOH/CHCl 3 50:50, v/v%) were tested. In the SF process, tert-butanol ( tBuOH) was used as solvent. The feed solution was injected into liquid nitrogen through a capillary nozzle located above the surface of the boiling nitrogen. Frozen particles were collected and freeze-dried for 30 h. Formulations were compared in terms of particle morphology, particle size, flow properties, crystallinity, polymorphic purity, residual solvent content, precipitation yield, drug content, specific surface area and dissolution kinetics. SAS and SF processed formulations exhibited enhanced dissolution rates. Within 5 min, the amount of dissolved drug varied from 31.6 to 64.3% for SAS and from 77.9 to 96.9% for freeze-dried formulations while only 30.5% was dissolved from raw drug. Apart from oxeglitazar/PVP K17, SAS prepared solid dispersions were characterized by high crystallinity and acicular shape. Freeze-dried formulations consisted of porous spherical particles with high amorphous content (94.2–100%).

Experimental measurements and correlations of vapor–liquid equilibrium data for the binary system of chloroform + N,N-dimethylformamide at 101.3 kPa

Vapor–liquid equilibrium data of chloroform–N,N-dimethylformamide (DMF) system are first determined at 101.3 kPa by using the equilibrium distiller. The binary VLE data are correlated by NRTL, UNIQUAC and Wilson models respectively. The activity coefficients are obtained by the simplex method. Average relative deviations between the calculated values with the three models and the experimental data of gas phase mole fraction are all less than 2.24%, and average relative deviations between calculated values and the experimental data of temperature are all less than 0.62%. The root mean square deviations (RMSD) of compositions and temperature are less than 0.005 and 0.7 K, respectively. Thermodynamic consistency of the experimental data is tested according to Herington method. It is demonstrated that calculated results of NRTL, UNIQUAC and Wilson equations are all in good agreement with the experimental data, and that azeotrope behavior is not found for the binary system of chloroform + DMF. The results not only provide the basis for analysis and design of distillation process, but also promote the development of new technology to recover DMF from wastewater.

Acceleration of the Substrate Cα Deprotonation by an Analogue of the Second Substrate Palmitoyl-CoA in Serine Palmitoyltransferase

Serine palmitoyltransferase (SPT) is a key enzyme of sphingolipid biosynthesis and catalyzes the pyridoxal 5'-phosphate (PLP)-dependent decarboxylative condensation reaction of l-serine with palmitoyl-CoA to generate 3-ketodihydrosphingosine. The binding of l-serine alone to SPT leads to the formation of the external aldimine but does not produce a detectable amount of the quinonoid intermediate. However, the further addition of S-(2-oxoheptadecyl)-CoA, a nonreactive analogue of palmitoyl-CoA, caused the apparent accumulation of the quinonoid. NMR studies showed that the hydrogen-deuterium exchange at Calpha of l-serine is very slow in the SPT-l-serine external aldimine complex, but the rate is 100-fold increased by the addition of S-(2-oxoheptadecyl)-CoA, showing a remarkable substrate synergism in SPT. In addition, the observation that the nonreactive palmitoyl-CoA facilitated alpha-deprotonation indicates that the alpha-deprotonation takes place before the Claisen-type C-C bond formation, which is consistent with the accepted mechanism of the alpha-oxamine synthase subfamily enzymes. Structural modeling of both the SPT-l-serine external aldimine complex and SPT-l-serine-palmitoyl-CoA ternary complex suggests a mechanism in which the binding of palmitoyl-CoA to SPT induced a conformation change in the PLP-l-serine external aldimine so that the Calpha-H bond of l-serine becomes perpendicular to the plane of the PLP-pyridine ring and is favorable for the alpha-deprotonation. The model also proposed that the two alternative hydrogen bonding interactions of His(159) with l-serine and palmitoyl-CoA play an important role in the conformational change of the external aldimine. This is the unique mechanism of SPT that prevents the formation of the reactive intermediate before the binding of the second substrate.

Effect of Fabrication Conditions on the Performance of MEH-PPV: PCBM Photovoltaic Devices

In this article, we fabricated photovoltaic devices based on poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV), as a donor and [6,6]-phenyl C61-butyric acid methyl ester(PCBM) as an electron acceptor materials. The effect of different solvents such as chlorobenzene, o-dichlorobenzene, chloroform, and cosolvent systems prepared with 1:1 ratio of chlorobenzen:o-dichlorobenzene, chlorobenzen:chloroform and o-dichlorobenzene:chloroform on the performance of devices was studied. Further, the effect of a thin electron transport layer of Alq3 inserted between active layer and cathode in the device structure, on the performance of devices was studied with the best solvent.

Use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents in ionic liquid extraction system

Possible use of 8-sulfonamidoquinoline derivatives as chelate extraction reagents for solvent extraction of several divalent metal cations using an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF 6]) as extraction phase was investigated as fundamental approach to develop novel extraction reagents for ionic liquid extraction system. The studied reagents were able to be used as extractants for the metal cations in the [bmim][PF 6] extraction system. Furthermore, their extractability in the [bmim][PF 6] system was superior to that in chloroform system. Most of the extracted species were (hydrated) neutral complexes, whereas, in use of the derivative having trifluoromethyl group, Cd 2+ was extracted as anionic complex accompanied with anion-exchange process.

Ultracentrifuge‐Mediated Diels—Alder Reaction in a Two‐Phase System of Water and Chloroform.

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