Effect Of Solvent System Research Articles

Bifunctional Metal-Organic Nanoballs Featuring Lewis Acidic and Basic Sites as a New Platform for One-Pot Tandem Catalysis.

The design and synthesis of polyhedra using coordination-driven self-assembly has been an intriguing research area for synthetic chemists. Metal-organic polyhedra are a class of intricate molecular architectures that have garnered significant attention in the literature due to their diverse structures and potential applications. Hereby, we report Cu-MOP, a bifunctional metal-organic cuboctahedra built using 2,6-dimethylpyridine-3,5-dicarboxylic acid and copper acetate at room temperature. The presence of both Lewis basic pyridine groups and Lewis acidic copper sites imparts catalytic activity to Cu-MOP for the tandem one-pot deacetalization-Knoevenagel/Henry reactions. The effect of solvent system and time duration on the yields of the reactions was studied, and the results illustrate the promising potential of these metal-organic cuboctahedra, also known as nanoballs for applications in catalysis.

Promoted Raney Ni catalyzed hydrodefluorination of fluorophenols under mild conditions via controlling solvents and bases

Fluorinated organic compounds (FOCs) are difficult to degrade and persistent in the environment due to the strong CF bond strength. In this context, the applicability of Raney Ni to catalytic hydrodefluorination (HDF) of FOCs under mild conditions remains an important challenge. In this study, the effects of solvent systems and bases on Raney Ni catalyzed HDF reaction were investigated and evaluated with 4-FP using as a model fluoroaromatic compound (FAC). It was found that the HDF reactivity of 4-FP over Raney Ni increased with the increase of water proportion and polarity of homogeneous ethanol–water solvents, and Raney Ni exhibited highest activity and stability in catalytic HDF of 4-FP in water with appropriate NaOH amount (1.5NaOH) under mild conditions. The mechanisms of these phenomena were clarified with the aid of catalyst characterization (SEM, EDX, and XRD) combined with ICP-OES. The results suggested that water could efficiently dissolve inorganic salt (NaF) produced in situ, which avoided the decrease in the catalytic activity of Raney Ni in the HDF of 4-FP due to the deposition of NaF on the surface of the catalyst. Moreover, the appropriate NaOH amount (1.5NaOH) in water could efficiently avoid the corrosion effect of HF on Raney Ni and eliminate the framework collapse of the catalyst resulted from the corrosion of Al. In water with 1.5NaOH, Raney Ni exhibited the highest activity and stability in catalytic HDF of 4-FP, with a complete conversion of 4-FP for at least 10 times. Based on these studies, an efficient reaction system was developed for Raney Ni catalyzed HDF of 4-FP, which would provide guidance to apply Raney Ni for catalytic HDF of FACs under mild conditions.

Flexible centrifugally spun PVP based SnO2@carbon nanofiber electrodes

Sodium-ion batteries (SIBs) have attracted significant attention because of the abundant resource and low-cost of sodium. Furthermore, flexible and wearable functional electronics have been presented as one of the most important emerging technology. Carbon nanofibers are promising candidates for flexible electrodes due to their high electronic conductivity and high surface area, while it is vital to use non-petroleum-based polymers considering environmental concerns. Developing flexible nanostructured electrodes by using environment friendly polymers with a fast and low-cost technique is critical to develop high performance flexible electronics. Electrochemical properties are influenced by the morphology and average fiber diameters of nanofibers. In this study, poly(vinylpyrrolidone) (PVP) solutions with various concentrations and two different solvent systems (ethanol/water and ethanol/dimethylformamide) were successfully spun into nanofibers by the fast, safe, low-cost, and environment friendly technique of centrifugal spinning. The effect of solvent system and solution concentration was investigated by using scanning electron microscopy images, and the average fiber diameters varied from 436 nm to 3 µm. Moreover, nine different heat treatments were studied, and the effect of time and temperature during stabilization and carbonization on the morphology of carbon nanofibers (CNFs) was investigated. Furthermore, flexible carbon nanofibers were fabricated and used as binder-free anodes in sodium-ion batteries. In order to enhance the electrochemical properties of flexible CNFs, flexible SnO2@CNFs were fabricated by combining centrifugal spinning and heat treatment. The electrochemical performance of the flexible SnO2@carbon nanofiber anodes was evaluated by conducting galvanostatic charge/discharge tests and cycling voltammetry. A high rate of performance was also presented. The high reversible capacity of 400 mA h/g was delivered when flexible centrifugally spun PVP based SnO2@carbon nanofiber electrodes were used in SIBs.

Effect of solvent systems on the synergistic catalytic hydrogenolysis of alkaline lignin over Pd/C-NaOH

Solvents and catalysts are two of the most critical factors for the depolymerization of lignin. This paper investigated the effect of different pure solvents on the hydrogenolysis of the β-O-4 MC and one of the mixed solvents on the hydrogenolysis of alkaline lignin. It was found that MC had higher conversion (96.5% and 94.3%) and monophenol yield (83.4 wt% and 77.9 wt%) in ethanol and 1,4-dioxane. The effects of different ratios of mixed solvents (ethanol-H2O and 1,4-dioxane-H2O), reaction conditions (temperature, time, pressure), and the synergistic effect of alkali and Pd/C catalysts on the hydrogenolysis of alkaline lignin were investigated in this paper. The composition, structure, and distribution of the lignin degradation products were also analyzed by GC, GC–MS, GPC, FT-IR, and 2D-HSQC. The results showed that the optimum monomer yields were 37.5 wt% and 24.7 wt% for ethanol-H2O and 1,4-dioxane-H2O at 3:2 (v:v) and 2:3 (v:v), respectively. The optimum yields were obtained at 260 °C, 2 MPa H2, and 4 h. The properties of solvent (protic polar solvent, nonpolar aprotic solvent) could influence the hydrogenolysis greatly and selectively break bonds. The different ratios of solvents in the mixed solvent systems influenced the solubility of alkaline lignin and its hydrogenolysis results. In addition, the synergistic effect of Pd/C and NaOH could improve the monomer yield and inhibit the polymerization of intermediates in hydrogenolysis.

Influence of solvent system on the optoelectrical properties of PCL/carbon black nanofibers

In this study, conductive and transparent polycaprolactone (PCL)/carbon black (CB) nanofibers are produced by electrospinning. In order to investigate the effect of solvent system on the optoelectrical properties of PCL/CB nanofibers, the fibers are produced from two different solvent systems; namely, chloroform (CHL) and dimetyl formamid (DMF). For optoelectrical characterization, nanofibers are produced with different deposition times in the range of 1–10 minutes. Surface, optical, electrical and optoelectrical properties of the PCL/CB nanofibers are evaluated. Nanofibers produced from CHL solvent system results in non-uniform nanofibers with higher diameters. They also give a larger diameter distribution. On the other hand, nanofibers with uniform and smaller diameters are obtained from DMF system. UV-spectrophotometer analysis show that nanofiber mats produced from both solvent systems have similar optical transparencies. Lower sheet resistance values are obtained with the nanofiber mats produced from DMF system according to electrical characterizations. Higher Figure of Merit values are calculated for the nanofiber mats produced in DMF solvent system. Considering all the results, it can be concluded that PCL/CB nanofibers produced from DMF solvent system are better candidates compared to the nanofibers produced from CHL solvent system for optoelectrical applications.

Mechanistic effects of solvent systems on the Ni–Sn-catalyzed hydrodeoxygenation of lignin derivatives to none-oxygenates

The influence of water on the organic reaction system and bimetallic Ni–Sn catalyst and the solvent property analysis of the cresol hydrodeoxygenation process to produce completely deoxidised product selective promoters.

Controlled synthesis and luminescent properties of Ca0.80Yb0.20F2.2: 0.2 % Tm3+ nanocrystals

In this paper, a series of high quality Ca0.80Yb0.20F2.2: 0.2 % Tm3+ nanocrystals (NCs) with size range from 3.2 nm ∼ 18.6 nm were obtained via solvothermal method by changing reaction conditions. The effect of solvent system, fluorine source, reaction temperature, ratio of F−/Ca(CF3COO)2 and reaction time on the growth of NCs were investigated systematically by X-ray diffraction (XRD), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). It was founded that solvent system and fluorine source has a more prominent influence on the growth of NCs compared with the other parameters. Besides, upconversion luminescent (UCL) properties and luminescence lifetime (τ) of 1G4 excited state of Tm3+ for the synthesized NCs were studied. Long decay lifetime of 1.15 ms with pulse laser excitation at 980 nm was found. This method can be used to prepare other NCs with high luminescence efficiency which can be further used for biomedical applications.

Electrospraying the Triblock Copolymer SEBS: The Effect of Solvent System and the Embedding of Quantum Dots

Electrospraying the Triblock Copolymer SEBS: The Effect of Solvent System and the Embedding of Quantum Dots

Tuning surface texture of electrospun polycaprolactone fibers: Effects of solvent systems and relative humidity

Abstract

Electrospraying the Triblock Copolymer SEBS: The Effect of Solvent System and the Embedding of Quantum Dots

AbstractThis work reports on ABA triblock copolymer microparticles encoded with CdSe/CdS core–shell quantum dots (QDs) realized by electrospraying. This method allows for simple but efficient embedding of QDs in polymer beads while retaining the fluorescent properties of the original QDs. The creation of poly(styrene‐ethylene‐butylene‐styrene) (SEBS) monodisperse spherical microparticles with a tunable morphology for applications of the final QD‐loaded product is attainable via solvent variation. By varying the selectivity of the solvent for one of the distinct blocks in the polymer, the final particle morphology can be selectively altered while maintaining the same overall process conditions, allowing to tailor the particles from homogeneously flat in a nonselective solvent to dense spherical particles in an endblock selective solvent system. The mechanism responsible for this transition in morphology can be related to differences in mass transfer in the droplets and thus solvent evaporation rates arising from particular microphase structures. Finally, fluorescence characteristics of the final QD‐embedded polymer particles and photodegradation stability are investigated by spectrophotometry and are compared to the temporal evolution of the original QDs, indicating significant stability improvement and well‐dispersed QDs in an optimized polymer matrix morphology.

An efficient synthesis of 2,3,5-trimethylbenzoquinone by metal-free oxidation of 1,2,4-trimethylbenzene

The oxidation of 1,2,4-trimethylbenzene with phthaloyl peroxide has been investigated under solvent-free and optimized conditions. 2,3,5-Trimethylbenzoquinone was obtained with great purity in 92% yield at 95% conversion of 1,2,4-trimethylbenzene at 120°C for 2.5 h under solvent-free conditions. The important factors such as the efficiency of the different cyclic acid anhydrides or carboxylic acid peroxides, the concentration of phthalic anhydride and 30% H2O2, the reaction time, the effect of solvent system, and the reaction temperature have been studied. An important advantage of this oxidizing system, aside from the organic solvent-free conditions, is that it is non-toxic, eco-friendly, and inexpensive. In addition, this methodology will be of great use in the preparation of commercially valuable benzoquinones from the corresponding aromatic compounds.

Studies on solvent systems for enhanced skin permeation of venlafaxine hydrochloride

Venlafaxine hydrochloride (VH) is a serotonin-noradrenaline reuptake inhibitor indicated for treatment of depression disorder. It shows low biological half-life 5±2 h and low oral bioavailability 45±15 % due to extensive hepatic first-pass metabolism. Frequent administration of VH is required to maintain steady state plasma concentration of drug. To overcome hepatic first pass metabolism and to cross blood brain barrier for effectively achieving plasma concentration of VH in brain, we envisaged to develop transdermal drug delivery system containing VH loaded polymeric nanoparticles. Effect of solvent systems (SS), penetration enhancers (PE), and VH nanoparticles (VHNPs) on transdermal diffusion of drug were studied. VHNPs were prepared by double emulsion solvent evaporation method using high speed homogenizer followed by probe sonication. Poly (lactic-co-glycolic acid) and tween 80 were used as polymer and surfactant respectively. Mean particle size, polydispersity index, zeta potential, entrapment efficiency of optimized VHNPs were found to be 175.4 nm, 0.109, (-) 24 mV and 56 %.respectively. Scanning electron microscopy confirmed spherical shape of drug loaded polymeric nanoparticles. SS comprising 50% PG in EtOH shown maximum flux 158.67 ± 2.9 (µg/cm2/h) and lag time was found to be 5.60 ±0.16 h. The PE 5 (%v/v) limonene shown maximum flux 200.47±3.6 (µg/cm2/h) and lag time 3.17±0.11 h. The flux and lag time in case of VHNPs were found to be 192.24±3.20 (µg/cm2/h) and 4.22±0.14 h respectively. Based on flux, clearance and surface area of transdermal patch, a theoretical meaningful plasma level concentration of VH ranging from 12.85 to 128.5 (ng/mL) can be achieved.
 Keywords: Depression, Venlafaxine hydrochloride, Poly (lactic-co-glycolic acid), Solvent systems, Penetration enhancers, Nanoparticles (NPs)

Purification of Flavonoids from Mulberry Leaves via High-Speed Counter-Current Chromatography

In order to obtain high-purity flavonoid products, the extracts from mulberry leaves were separated and purified via high-speed counter-current chromatography (HSCCC). Moreover, the product was detected via high-performance liquid chromatography (HPLC). The characteristic absorption wavelength of the rutin standard for HSCCC detection and HPLC analysis at 257 nm was tested by ultraviolet scanning analysis. The effect of solvent systems and mobile phase flow rate on the separation efficiency were then researched. Finally, the solvent system of V(ethyl acetate):V(n-butanol):V(water) = 4:1:5 was selected as the operating system for HSCCC. This work theoretically analyzed the impact of the molecular structure and polarity of flavonoids on the choice of solvent systems. The results showed that the mobile phase flow rate had a great influence on the separation efficiency. Furthermore, the separation efficiency increased as the mobile phase flow rate decreased. When the mobile phase flow rate was 5 mL/min, the peak time for flavonoids was 140 min, the retention of the stationary phase was 56.4%, and the purity of the product reached 93.8%. The results of this study greatly improved the purity of flavonoids in mulberry leaf and provided a strong support for the separation and purification of mulberry leaf extract.

Carbon Sequestration: Hydrogenation of CO2 to Formic Acid

Abstract The concentration CO2 gas has become a great worldwide challenge because CO2 is considered as an important counterpart of greenhouse gases. The tremendous increase in the concentration of CO2 gas, elevated the worldwide temperature as well as it altered the climatic changes. Various physiochemical approached have been reported to trap the CO2 gas and the chemical conversion of CO2 to useful chemicals is one of them. This review covers the conversion of CO2 gas to formic acid. In this CO2 hydrogenation reaction, both the homogeneous as well as heterogeneous catalytic systems were discussed along with the effect of solvent systems on reaction kinetics.

Effect of Solvent System on Extractability of Lipidic Components of Scenedesmus obliquus (M2-1) and Gloeothece sp. on Antioxidant Scavenging Capacity Thereof.

Microalgae are well known for their biotechnological potential, namely with regard to bioactive lipidic components—especially carotenoids and polyunsaturated fatty acids (PUFA), well-known for therapeutic applications based on their antioxidant capacity. The aim of this work was to evaluate the influence of four distinct food-grade solvents upon extractability of specific lipidic components, and on the antioxidant capacity exhibited against both synthetic (2,2-diphenyl-1-picrylhydrazyl (DPPH•) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS+•)) and biological reactive species (O2•− and •NO−). A eukaryotic microalga (Scenedesmus obliquus (M2-1)) and a prokaryotic one (Gloeothece sp.) were used as case studies. Concerning total antioxidant capacity, the hexane:isopropanol (3:2) and acetone extracts of Sc. obliquus (M2-1) were the most effective against DPPH• and ABTS+•, respectively. Gloeothece sp. ethanol extracts were the most interesting scavengers of O2•−, probably due the high content of linolenic acid. On the other hand, acetone and hexane:isopropanol (3:2) extracts were the most interesting ones in •NO− assay. Acetone extract exhibited the best results for the ABTS assay, likely associated to its content of carotenoids, in both microalgae. Otherwise, ethanol stood out in PUFA extraction. Therefore, profiles of lipidic components extracted are critical for evaluating the antioxidant performance—which appears to hinge, in particular, on the balance between carotenoids and PUFAs.

Synthesis and characterization of imine-functionalized polyphenol via enzymatic oxidative polycondensation of a bisphenol derivative

Enzymatic oxidative polycondensation of a new bisphenol derivative 3,3′-((1E,1′E)-(1,3-phenylenebis(azanylylidene))bis(methanylylidene))diphenol, (3,3′-PBAMD), using horseradish peroxidase (HRP) enzyme and hydrogen peroxide (H2O2) oxidizer for initiation of the reaction, has been investigated in an equivolume mixture of an organic solvent (acetone, methanol, ethanol, dichloromethane, 1,4-dioxane and tetrahydrofuran) and phosphate buffer (pH = 5.0, 6.0, 7.0, 8.0 and 9.0) at different temperatures under air for 24 h. The resulting polymer, poly(3,3′-PBAMD), was characterized using ultraviolet–visible (UV–Vis), Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and thermogravimetric (TGA) analyses. Effects of solvent system, reaction temperature and pH on the polymerization have been investigated with respect to the yield and molecular weight (M n) of the product. The optimum reaction condition in terms of the highest yield (81 %) and molecular weight (M n = 10,500 g/mol, DP ~33) was achieved in an equivolume mixture of tetrahydrofuran/pH 7.0 phosphate buffer medium at 25 °C. Polymerization involved hydrogen elimination from the monomer, and terminal units of the polymer structure consisted of phenolic hydroxyl (–OH) groups at the ends. The polymer is mainly composed of a mixture of phenylene and oxyphenylene units according to 1H NMR and FT-IR analyses. The resulted product has shown relatively high thermal stability against thermal decomposition, and 35 % of the initial weight of the sample (carbonaceous residue) remained after heating to 1000 °C.

Electrospinning of Grooved Polystyrene Fibers: Effect of Solvent Systems.

Secondary surface texture is of great significance to morphological variety and further expands the application areas of electrospun nanofibers. This paper presents the possibility of directly electrospinning grooved polystyrene (PS) fibers using both single and binary solvent systems. Solvents were classified as low boiling point solvent (LBPS): dichloromethane (DCM), acetone (ACE), and tetrahydrofuran (THF); high boiling point solvent (HBPS): N,N-dimethylformamide (DMF) and cyclohexanone (CYCo); and non-solvent (NS): 1-butanol (BuOH). By the systematic selection and combination of these solvents at given parameters, we found that single solvent systems produced non-grooved fibers. LBPS/DMF solvent systems resulted in fibers with different grooved textures, while LBPS/CYCo led to fibers with double grooved texture. Grooved fibers can also be fabricated from LBPS/LBPS, NS/LBPS, and NS/HBPS systems under specific conditions. The results indicated that the difference of evaporation rate (DER) between the two solvents played a key role in the formation of grooved texture. The formation of this unique texture should be attributed to three separate mechanisms, namely void-based elongation, wrinkle-based elongation, and collapsed jet-based elongation. Our findings can serve as guidelines for the preparation of ultrafine fibers with grooved secondary texture.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-0949-5) contains supplementary material, which is available to authorized users.

Enzymatic oxidative polymerization of para‐imine functionalized phenol catalyzed by horseradish peroxidase

Enzymatic oxidative polymerization of a new para‐imine functionalized phenol derivative, 4‐(4‐hydroxybenzylideneamino)benzoic acid (HBBA), using horseradish peroxidase enzyme and hydrogen peroxide oxidizer has been investigated in an equivolume mixture of an organic solvent (acetone, methanol, ethanol, dimethylformamide, 1,4‐dioxane, and tetrahydrofuran) and phosphate buffer (pH = 5.0, 6.0, 6.8, 7.0, 7.2, 8.0, and 9.0) at different temperatures under air for 24 h. The resulting oligomer, oligo(4‐(4‐hydroxybenzylideneamino)benzoic acid) [oligo(HBBA)], was characterized using ultraviolet–visible, Fourier transform infrared (FT‐IR), 1H nuclear magnetic resonance (NMR), cyclic voltammetry, size exclusion chromatography, differential scanning calorimetry, and thermogravimetric analyses. Polymerization involved carbon dioxide and hydrogen elimination from the monomer, and terminal units of the oligomer structure consisted of phenolic hydroxyl (–OH) groups at the ends. The polymer is mainly composed of a mixture of phenylene and oxyphenylene units according to 1H NMR and FT‐IR analyses. Effects of solvent system, temperature and buffer pH on the polymerization have been investigated in respect to the yield and molecular weight (Mn) of the product. The best condition in terms of the highest molecular weight (Mn = 3000 g/mol, DP ~ 15) was achieved in an equivolume mixture of 1,4‐dioxane/pH 5.0 phosphate buffer condition at 35°C. Electrochemical characterization of oligo(HBBA) was investigated at different scan rates. The resulting oligomer has also shown relatively high thermal stability according to thermogravimetric analysis. Copyright © 2015 John Wiley & Sons, Ltd.

Graphene/Ionic liquid composite films and ion exchange.

Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force.

Evaluation of <i>In vitro</i> and <i>In vivo</i> Performance of Granisetron In situ Forming Implants: Effect of Sterilization, Storage Condition and Degradation

Purpose: To investigate the effect of various solvent systems and gamma irradiation on the in vitro and in vivo performance of granisetron HCl injectable phase-sensitive in situ forming implants (ISFIs).Methods: ISFIs were prepared by mixing and sterilized by gamma irradiation. Effect of solvent system was studied. Injectability, polymer degradation and stability studies (4 and 25 oC for 4 months), viscositymeasurements, as well as in vitro and in vivo (in rabbits) drug release, and also histological examinations for biocompatibility studies (in rabbits and rats) were carried out.Results: ISFIs showed good injectability from 20-gauge needle and their in vitro drug release increased in the following rank order of solvent/solvent combinations: dimethylsulphoxide (DMSO) > DMSO:prophylenecarbonate (PC) > DMSO:triacetin(TA) > DMSO:benzylbenzoate (BB). DMSO:PC incorporating ISFI gave zero order (r2 = 0.9503) drug release for 21 days; application of gamma irradiation accelerated drug release with a difference factor (f1) of 53 but zero order release (r2 = 9690) was maintained. Following test results for DMSO:PC including ISFI as decrease in molecular weight of polymer was descriptive for drug release behavior and sterilization effect, additionally dynamic viscosities decreased in line with polymer degradation and all forms of this ISFI showed plastic flow(fresh, irradiated, aged at 4 and 25 oC for 4 months). In vivo performance showed steady state plasma drug concentrations between 2 to 21 days with value of 0.55 ± 0.03 ìg/ml and biocompatibility was confirmed by histological results obtained at specific stages of tissue reactions, and also by lack of fibrous capsule formation.Conclusion: An ISFI for long-term antiemetic therapy achieved in this preliminary study is promising and, therefore, further investigations are required.Keywords: Implant, Poly(DL-lactide-co-glycolide), Granisetron, Gamma irradiation, Sterilization, Degradation, Viscosity, Stability, Pharmacokinetic, Biocompatibility.