Solution-phase Approach Research Articles

6-(1-Benzyl-1H-pyrrol-2-yl)-2,4-dioxo-5-hexenoic Acids as Dual Inhibitors of Recombinant HIV-1 Integrase and Ribonuclease H, Synthesized by a Parallel Synthesis Approach

The increasing efficiency of HAART has helped to transform HIV/AIDS into a chronic disease. Still, resistance and drug-drug interactions warrant the development of new anti-HIV agents. We previously discovered hit 6, active against HIV-1 replication and targeting RNase H in vitro. Because of its diketo-acid moiety, we speculated that this chemotype could serve to develop dual inhibitors of both RNase H and integrase. Here, we describe a new series of 1-benzyl-pyrrolyl diketohexenoic derivatives, 7a-y and 8a-y, synthesized following a parallel solution-phase approach. Those 50 analogues have been tested on recombinant enzymes (RNase H and integrase) and in cell-based assays. Approximately half (22) exibited inhibition of HIV replication. Compounds 7b, 7u, and 8g were the most active against the RNase H activity of reverse-transcriptase, with IC50 values of 3, 3, and 2.5 μM, respectively. Compound 8g was also the most potent integrase inhibitor with an IC50 value of 26 nM.

SnS2 nanoflakes decorated multiwalled carbon nanotubes as high performance anode materials for lithium-ion batteries

SnS2 nanoflakes decorated multiwalled carbon nanotubes (MWCNTs) hybrid structures are directly synthesized via a simple solution-phase approach. The as-prepared SnS2/MWCNTs structures are investigated as anode materials for Li-ion batteries as compared with SnS2 nanoflakes. It has been found that the composite structure exhibit excellent lithium storage performance with a large reversible capacity, superior cycling performance, and good rate capability as compared to pure SnS2 nanoflakes. The first discharge and charge capacities have been found to be 1416 and 518mAhg−1 for SnS2/MWCNTs composite electrodes at a current density of 100mAg−1 between 5mV and 1.15V versus Li/Li+. A stable reversible capacity of ∼510mAhg−1 is obtained for 50 cycles. The improved electrochemical performance may be attributed to the flake-morphology feature of SnS2 and the addition of MWCNTs that can hinder the agglomeration of the active materials and improve the conductivity of the composite electrode simultaneously.

Automated Solid‐Phase Synthesis of a β‐(1,3)‐Glucan Dodecasaccharide

β-Glucans are a group of structurally heterogeneous polysaccharides found in bacteria, fungi, algae and plants. β-(1,3)-D-Glucans have been studied in most detail due to their impact on the immune system of vertebrates. The studies into the immunomodulatory properties of these glucans are typically carried out with isolates that contain a heterogeneous mixture of polysaccharides of different chain lengths and varying degrees of branching. In order to determine the structure-activity relationship of β-(1,3)-glucans, access to homogeneous, structurally-defined samples of these oligosaccharides that are only available through chemical synthesis is required. The syntheses of β-glucans reported to date rely on the classical solution-phase approach. We describe the first automated solid-phase synthesis of a β-glucan oligosaccharide that was made possible by innovating and optimizing the linker and glycosylating agent combination. A β-(1,3)-glucan dodecasaccharide was assembled in 56 h in a stereoselective fashion with an average yield of 88% per step. This automated approach provides means for the fast and efficient assembly of linker-functionalized mono- to dodecasaccharide β-(1,3)-glucans required for biological studies.

High-Temperature Solution-Phase Syntheses of Metal-Oxide Nanocrystals

This review highlights the recent progress in synthesizing some representative metal-oxide nanocrystals (MONCs) with controlled magnetic, electronic, and optical properties for potentially important technological applications. It first introduces the synthesis of MONCs of magnetite (Fe3O4), ferrite (MFe2O4), and hollow Fe3O4 with controlled magnetic properties. It then highlights the potentials of these nanocrystals (NCs) as highly effective contrast enhancement agents for magnetic resonance imaging (MRI) and as efficient nanoplatforms for target specific drug delivery. The review further surveys some typical high-temperature solution-phase approaches to the common semiconductive MONCs of indium tin oxide (ITO, In2O3·xSnO2)/tin oxide (SnO2), zinc oxide (ZnO), titanium oxide (TiO2), and copper oxide (Cu2O or CuO) with controlled band-gap energies and optical properties for optoelectronics, photocatalysis, and sensor applications.

Tuning the magnetic properties of metal oxide nanocrystal heterostructures by cation exchange.

For three types of colloidal magnetic nanocrystals, we demonstrate that postsynthetic cation exchange enables tuning of the nanocrystal’s magnetic properties and achieving characteristics not obtainable by conventional synthetic routes. While the cation exchange procedure, performed in solution phase approach, was restricted so far to chalcogenide based semiconductor nanocrystals, here ferrite-based nanocrystals were subjected to a Fe2+ to Co2+ cation exchange procedure. This allows tracing of the compositional modifications by systematic and detailed magnetic characterization. In homogeneous magnetite nanocrystals and in gold/magnetite core shell nanocrystals the cation exchange increases the coercivity field, the remanence magnetization, as well as the superparamagnetic blocking temperature. For core/shell nanoheterostructures a selective doping of either the shell or predominantly of the core with Co2+ is demonstrated. By applying the cation exchange to FeO/CoFe2O4 core/shell nanocrystals the Neél temperature of the core material is increased and exchange-bias effects are enhanced so that vertical shifts of the hysteresis loops are obtained which are superior to those in any other system.

Multicolor and Fast Electrochromic P(DTB-EDOT)/ZnO Nanocomposite Film

In this work, uniform and controllable size of ZnO nanoparticles were fabricated via solution-phase approach, and the copolymer based on the monomers of 1,4-di(thiophen-3-yl)benzene (DTB) and 3,4-ethylenedioxythiophene (EDOT) was successfully synthesized with electrochemical polymerization. A new P(DTB-EDOT)/ZnO nanocomposite film was obtained via situ preparation. Cyclic voltammogram and spectroelectrochemical characterization showed that the composite film had a stable and well-defined reversible redox process as well as electrochromic behavior. Besides, the composite film exhibited fast switching time (1 s at 746 nm), significant optical contrast and a variety of colors (red, ochre, green and blue) under different potentials.

Polyhydrosilane Mediated Synthesis of One-Dimensional Gold Nanostructures

This work presents a solution-phase approach for the “one pot” synthesis of polysilane-gold nanorods. The process starts by the reduction of HAuCl4 to Auo with a solution of poly[diphenylsilane-co-methyl(H)silane] cooled to 4 °C. The formed small Au nanoparticles (5–15 nm diameter) serve further as seeds for the heterogeneous nucleation and anisotropic growth that takes place at 25 °C and yields crystalline needle-like polymer–gold nanostructures. The evolution of the small spherical nanoparticles to nanorods with length/width aspect ratios up to 103 has been proved by UV–Vis spectroscopy, polarized light microscopy and AFM. Further insights on the growth mechanism were obtained by SEM, DLS and TEM.

Solution phase synthesis of silicon and germanium nanowires

Si and Ge nanowires have attracted widespread interest due to their suitability for photovoltaic, nanoelectronic, sensing and energy storage applications. As a result, a variety of synthetic protocols have emerged which include chemical vapour deposition and solution phase approaches. Early solution based approaches were hindered by the high nucleation temperatures required for Ge and Si NW formation but these have been overcome by using either supercritical fluid (SCF) approaches or high boiling point organic solvent (HBS) routes. This feature article examines the various synthetic strategies which have been successful in forming Ge and Si NWs within solvent based systems with particular emphasis on the reaction media and catalytic method employed.

Organic Luminescent Molecule/ZnO Nanocomposite Film with Colors Tuning

Various morphologies of ZnO nanostructures, including nanoparticle, nanotubes, and urchin-like ZnO and snowflake-like ZnO, were fabricated via solution-phase approaches. The morphology and crystallization of resulting Nano-ZnO were investigated by SEM, TEM, and XRD. The organic luminescent molecule (CNS-4) and ZnO nanocomposite films were cast from a common solvent mixture. The surface structures and optical properties of hybid films were investigated by SEM and PL spectra. The result indicated that ZnO nanocrystals incorporated with CNS-4 successfully tuned the colors of organic luminescent molecules, which could widen its applications on the LED displays.

Kinetically controlled synthesis of nickel tetrahedron nanocrystals for high performance catalytic hydrogenation

Ni nanocrystals with a tetrahedral shape were synthesized through a solution-phase approach with sodium citrate serving as a capping surfactant. A ferromagnetic Ni tetrahedron exclusively bound by {111} facets achieved superior catalytic activity for toluene hydrogenation compared to Ni nanoflowers and Ni nanoparticles.

Mild and cost-effective synthesis of iron fluoride–graphene nanocomposites for high-rate Li-ion battery cathodes

Exploring high performance cathode materials is essential to realize the adoption of Li-ion batteries for application in electric vehicles and hybrid electric vehicles. FeF3, as a typical iron-based fluoride, has been attracting considerable interest due to both the high electromotive force value of 2.7 V and the high theoretical capacity of 237 mA h g−1 (1e− transfer). In this study, we report a facile low-temperature solution phase approach for synthesis of uniform iron fluoride nanocrystals on reduced graphene sheets stably suspended in ethanol solution. The resulting hybrid of iron fluoride nanocrystals and graphene sheets showed high specific capacity and high rate performance for iron fluoride type cathode materials. High stable specific capacity of about 210 mA h g−1 at a current density of 0.2 C was achieved, which is much higher than that of LiFePO4 cathode material. Notably, these iron fluoride/nanocomposite cathode materials demonstrated superior rate capability, with discharge capacities of 176, 145 and 113 mA h g−1 at 1, 2 and 5 C, respectively.

Building self-ordered tubular macro- and mesoporous nitridated titania from gas bubbles towards high-performance lithium-ion batteries

Robust well-defined tubular structural materials based on macro- and mesoporous nitridated titania (TMMN-TiO2) were obtained by a simple solution-phase approach in ammonia solution. In this approach, the gas bubbles derived from ammonia solution play the role of templates that direct the ordered growth in the form of a tubular structure. The results demonstrated that the volume ratio of ammonia to water can be favorable for the formation of TMMN-TiO2, which are characterized by FESEM and FTIR. What is more, ammonia was used not only as the template but also as the nitrogen source. Interestingly, it was found that the TiO2 nanocrystals building blocks were assembled into an interconnected mesoporous skeleton and built in ordered tubular macroporous channels. This unique architecture provides many important features that are required for high-performance anodes, such as fast ion transport, high conductivity, and structure stability, thus enabling an electrode with outstanding lithium storage performance. For example, such an electrode delivers 112 mA h g(-1) capacity at 5100 mA g(-1) (30 C) even after 1200 cycles.

Solvated Graphenes: An Emerging Class of Functional Soft Materials

From a materials science point of view, graphene is essentially a polymer having a giant, two-dimensional molecular configuration. In this Progress Report, solvated graphene and its derivatives are illustrated from the perspective of soft matter. Firstly, the key appealing features of graphene as a molecular building block for assembling bulk soft materials are highlighed. It is then demonstrated how the intersheet interactions in solution are correlated with the molecular structure of graphene, and how a combination of the unique molecular structure and colloidal interactions can lead to simple, solution-phase approaches for assembling graphenes into a variety of macroscopic nanoarchitectures. A number of new exciting functions and applications are also highlighted, which are enabled by the solvation effect and in particular, it is discussed why and how solvated graphenes can offer exciting functions that are unattainable with the dried, hard counterpart. The discussion is concluded with some personal perspectives on the future directions in which this emerging class of functional soft materials could be pursued.

Effective photocatalytic degradation of rhodamine B dye by ZnO nanoparticles

Highly crystalline ZnO nanoparticles (NPs) were synthesized with zinc acetate as precursor and oxalic acid at 80°C through the simple solution phase approach. The synthesized ZnO NPs possessed monodispersity with the average size 20–30nm. The crystalline properties revealed the typical hexagonal wurtzite phase with orientation along c-axis. The photocatalytic activity investigation was carried out by performing the decomposition of rhodamine-B dye under UV illumination over as-synthesized ZnO NPs. The rhodamine B dye considerably degraded by ∼95% within 70min in the presence of as-synthesized ZnO NPs. An excellent rate constant (k=0.0343min−1) was obtained for the degradation of rhodamine B dye.

Solution‐Phase and Magnetic Approach towards Understanding Iron Gall Ink‐like Nanoassemblies

Metallhaltige Röhren: Die Strukturen mehrerer Eisen-haltiger C-Methylpyrogallol[4]aren(PgC1)-Nanoaggregate wurden in fester Phase und in Lösung untersucht. Die Aggregate haben eine röhrenförmige Architektur mit Eisen als Gerüstbestandteil (siehe Bild; grau C, rot O, türkis/blau Fe), und magnetische Analysen weisen auf eine gekippte oder spiralförmige Anordnung der Eisenzentren hin.

Solution-Phase and Magnetic Approach towards Understanding Iron Gall Ink-like Nanoassemblies

Metal-containing tubes: The structures of several iron-containing C-methylpyrogallol[4]arene (PgC1) nanoassemblies were studied in both the solid and solution phases. The nanoassemblies have a tubular architecture with the iron as part of the framework (see picture; gray C, red O, turquoise/blue Fe), and magnetic analysis suggests a canted or spiral arrangement of the iron centers.

A simple electrochemical approach to fabricate a glucose biosensor based on graphene–glucose oxidase biocomposite

We report a simple electrochemical approach for the immobilization of glucose oxidase (GOx) on reduced graphene oxide (RGO). The immobilization of GOx was achieved in a single step without any cross linking agents or modifiers. A simple solution phase approach was used to prepare exfoliated graphene oxide (GO), followed by electrochemical reduction to get RGO–GOx biocomposite. The direct electrochemistry of GOx was revealed at the RGO–GOx modified glassy carbon electrode (GCE). The electrocatalytic and electroanalytical applications of the proposed film were studied by cyclic voltammetry (CV) and amperometry. It is notable that the glucose determination has been achieved in mediator-free conditions. RGO–GOx film showed very good stability, reproducibility and high selectivity. The developed biosensor exhibits excellent catalytic activity towards glucose over a wide linear range of 0.1–27mM with a sensitivity of 1.85μAmM−1cm−2. The facile and easy electrochemical approach used for the preparation of RGO–GOx may open up new horizons in the production of cost-effective biosensors and biofuel cells.

Microwave-assisted synthesis and characterization of microstar shaped zinc oxide

A microwave-assisted solution-phase approach has been applied for the synthesis ofzinc oxide microstructures. Toe synthesis procedure was carried out by using the reagents: Zinc ni trate and Methenamine, at stoichiometric ratio. Analysis by means ofX-ray Diffraction (XRD) shows a crystalline phase in hexagonal wurtzite arrangement for ZnO. The presence ofmicrostar shaped zinc oxide (2-3μm) with nanorods,f50nm) arranged has been confirmed from High Resolution Scanning Electron Microscopy (HRSEM). The formation of nanorods was confirmed by Transmission Electron Microscopy. In Raman spectroscopy a red shift was detected in the microstructures compared with ZnO bulk. High crystalline materials without additional post-synthesis treatrnent were found.

Synthesis and characterization of Ag nanorods used for formulating high-performance conducting silver ink

Silver nanorods with ∼100 nm in diameter and ∼5 µm in length were synthesised by the soft solution-phase approach in the presence of poly(vinylpyrrolidone) (PVP), which was employed as a protecting agent. The obtained silver nanorods were characterised by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-visible spectrum. The molar ratio and injection rate of PVP and AgNO3 played an important role in controlling the morphology and aspect ratio of nanorods. The growth mechanism of silver nanorods was also discussed. Moreover, the conductive ink was prepared using as-synthesised products, and the electrical resistivity of the final consolidated trace with this kind of ink was up to 2.7 × 10−5 Ωcm.

Fast preparation of flower-like Bi4Ge3O12 microstructures via a microwave-assisted hydrothermal process

In the present paper, we report a facile and fast microwave-assisted solution-phase approach for the preparation of flower-like bismuth germanate (Bi4Ge3O12) microstructures, employing bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and germanium dioxide (GeO2) as starting materials. The phase and morphology of the products were characterized by powder X-ray diffraction, X-ray photoelectron spectrum, energy dispersive spectrometry, and scanning electron microscopy. Some control experiments have been carried out to reveal the influencing factors involved in the formation, which suggested that reaction time, reaction temperature, the volume of ammonia and glycerol play crucial roles in the formation of the flower-like Bi4Ge3O12. The optical absorption property of the product has been investigated.