SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: Chemistry, an Asian journal

28

High-quality reduced graphene, termed PG, has been synthesized by a simple, low-cost, and green plasma approach, and applied as adsorbent to remove 4,4'-dichloribiphenyl (4,4'-DCB) from aqueous solutions. As a comparison, the adsorption of 4,4'-DCB on graphene oxide (GO) and multiwalled carbon nanotubes (MWCNTs) was also studied under the same experimental conditions. PG performs significantly better with regard to 4,4'-DCB adsorption than GO and MWCNTs, or any reported nanomaterials, with a maximum adsorption capacity (q(max) ) of 1552 mg g(-1) at pH 7.0. The high affinity of 4,4'-DCB to PG is mainly a result of strong π-π interactions, as also confirmed by DFT calculations. The results reveal that PG sheets hold promise for the removal of persistent organic pollutants. We expect possible applications of this fast and mild plasma technique in the fabrication of nanomaterials and envisage their use in a variety of advanced chemical processes.

Concepts: Carbon dioxide, Chemistry, Carbon, Nanomaterials, Carbon nanotube, Graphene, Materials science, Graphene oxide paper

28

When size matters! Silver iodide nanoparticles (AgI NPs) with a mean diameter of 6.3±4.2 nm were synthesized using potassium iodide. The α phase of the AgI NPs was stable up to 37 °C, as determined by differential scanning calorimetry, which is in good agreement with variable temperature XRD measurements.

Concepts: Thermodynamics, Gold, Phase transition, Differential scanning calorimetry, Silver, Glass transition, Iodides, Silver iodide

28

The solution-dispersed-state and polymer-dispersed-state circular dichroism (CD) and circularly polarized luminescence (CPL) properties of chiral binaphthyl fluorophores could be controlled by the choice of open- or closed-type substituents on the binaphthyl units and by the axial chirality of the binaphthyls.

Concepts: Optics, Stereochemistry, Chirality, Polarization, Circular polarization, Circular dichroism, Axial chirality

28

Excimers are generally considered as detrimental to OLEDs. For pyrene-based chromophores, however, this is not always true. In this contribution, two new methylated tetraphenylpyrenes, 1,3,6,8-tetra-o-tolylpyrene (TTPy) and 1,3,6,8-tetrakis(3,5-dimethylphenyl)pyrene (TDMPPy), were synthesized through Suzuki coupling reactions. TDMPPy absorbs and emits light at longer wavelengths than TTPy due to its more planar conformation and thus better conjugation. TDMPPy is prone to excimer formation, thus leading to a strong bathochromic shift (84 nm) in the photoluminescence spectrum of its film. TDMPPy exhibits efficient electroluminescence originating from pyrene excimers, affording a maximum luminance of 26 670 cd m(-2) and a current efficiency as high as 10.8 cd A(-1) in a non-doped OLED (ITO/PEDOT:PSS (50 nm)/NPB (30 nm)/TDMPPy (30 nm)/TPBI (40 nm)/Ca:Ag).

Concepts: Spectroscopy, Bathochromic shift, Heck reaction, Wavelength, Suzuki reaction, Coupling reaction, Organic LED, Excimer

28

Recently, it has been proven that directional flow of photogenerated charge carriers occurs on specific facets of TiO(2) nanocrystals. Herein, we demonstrate that the photocatalytic activity of anatase TiO(2) nanocrystals in both photoreduction and photooxidation processes can be enhanced by selectively depositing Pt nanoparticles on the {101} facets, which strengthens spontaneously surface-induced separation between photogenerated electrons and holes in the photocatalysis process. An optimal ratio of the oxidative {001} facets to the reductive {101} facets exists with regard to the photocatalysis of the faceted TiO(2) nanocrystals, and this is crucial for balancing the recombination and redox reaction rates of photogenerated electrons and holes. The present work might help us gain deeper insight into the relation between the specific surface of semiconductor photocatalysts and their photocatalytic activities and provides us with a new route to design photocatalysts with high photocatalytic activity.

Concepts: Photosynthesis, Hydrogen, Redox, Titanium dioxide, Photocatalysis, Photocatalytic water splitting

27

Watch your figure: Three different shapes of TiO2 nanoparticles with various exposed facets have been synthesized by changing the adsorbents. The spindly octahedron with exposed high-index {401} facet exhibit the highest electrochemical performance than that of the other shapes.

Concepts: Titanium dioxide, Diamond, Rechargeable battery, Lithium-ion battery, Lithium-ion polymer battery, Octahedron, Lithium-ion batteries, Facet

27

A combination of the oxidative N-heterocyclic carbine catalysis and click chemistry has been explored for the direct, one-pot synthesis of 1,2,3-triazole derivatives from aromatic aldehydes. This procedure was found to be very efficient and a variety of 1,2,3-triazole derivatives could be accessed through their corresponding propargyl esters in moderate-to-good yields under mild conditions.

Concepts: Alcohol, Chemical reaction, Electrochemistry, Hydrogenation, Chemical synthesis, Carbonyl, Functional groups, Organic chemistry

27

Expand and diversify your Ptfolio: N-Heterocyclic carbene-Pt-pyridine complexes have been used to generate an expanded and diversified set of trans NHC-Pt complexes with various amines, polyamines, hydroxylamines, or hydrazine as ligands. Attachment of a fluorophore moiety has also been successfully achieved.

Concepts: Amine, Ammonia, Nitrogen, Cyanide, Ligand, Amide, Amines, Imine

27

Reading the tea leaves: The enatioselective total syntheses of (-)-8-C-ascorbylepigallocatechin was accomplished by Cu(II) -mediated oxidative coupling of ascorbic acid and (-)-epigallocatechin as a key step. Also, the asymmetric total syntheses of tea-leaf extracts (+)-gallocatechin and (-)-epigallocatechin were achieved by Au-catalyzed intramolecular cycliarylation of the precursor epoxide and Sharpless dihydroxylation.

Concepts: Antioxidant, Vitamin C, Ascorbic acid, Sharpless asymmetric dihydroxylation, Upjohn dihydroxylation, Asymmetric catalytic oxidation

27

Monodisperse hollow carbon nanocapsules (<200 nm) with mesoporous shells were synthesized by coating their outer shells with silica to prevent aggregation during their high-temperature annealing. Monodispersed silica nanoparticles were used as starting materials and octadecyltrimethoxysilane (C18TMS) was used as a carbon source to create core-shell nanostructures. These core-shell nanoparticles were coated with silica on their outer shell to form a second shell layer. This outer silica shell prevented aggregation during calcination. The samples were characterized by TEM, SEM, dynamic light scattering (DLS), UV/Vis spectroscopy, and by using the Brunauer-Emmett-Teller (BET) method. The as-synthesized hollow carbon nanoparticles exhibited a high surface area (1123 m(2)  g(-1) ) and formed stable dispersions in water after the pegylation process. The drug-loading and drug-release properties of these hollow carbon nanocapsules were also investigated.

Concepts: Spectroscopy, Nanoparticle, Sol-gel, Scientific techniques, Ultraviolet-visible spectroscopy, Light scattering, Dynamic light scattering, Rayleigh scattering