Facile synthesis of 1-(arylimino)naphthalen-2(1H)-ones from anilines and 2-naphthols promoted by NaBr/K2S2O8/CAN

An efficient method has been developed for the synthesis of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-naphthols promoted by NaBr/K₂S₂O₈/Ce(NH₄)₂(NO₃)₆. Using this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields (17 examples, 70–92% yields). The reactions may proceed through the following steps: bromination of 2-naphthols by in-situ-generated bromine from NaBr and K₂S₂O₈ to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-2-ols with anilines to afford the corresponding amines, and subsequent oxidation of the amines into the products by Ce(NH₄)₂(NO₃)_6. These newly obtained α-imine ketones have great potentials for synthesis of special optical materials bearing naphthalene moiety.     

Sensitive and selective fluorescence detection of aqueous uranyl ions using water-soluble CdTe quantum dots

Herein we report a fluorescent method for sensitive and selective detection of uranyl ions using CdTe quantum dots functionalized with mercaptopropionic acid, which the fluorescence of the quantum dots could be quantitatively quenched through electron transfer mechanism. The detection limit of the method was estimated to be 4 nM, less than the maximum allowed content of 130 nM for uranyl in drinking water defined by the U.S. Environmental Protection Agency. Furthermore, the probe was successfully applied in detection of uranyl ions in real samples, demonstrating its potential practical applications for monitoring of uranyl ions in environment.     

Electrospinning Synthesis of Porous NiCoO2 Nanofibers as High‐Performance Anode for Lithium‐Ion Batteries

Nanostructured ternary/mixed transition metal oxides have attracted considerable attentions because of their high‐capacity and high‐rate capability in the electrochemical energy storage applications, but facile large‐scale fabrication with desired nanostructures still remains a great challenge. To overcome this, a facile synthesis of porous NiCoO₂ nanofibers composed of interconnected nanoparticles via an electrospinning–annealing strategy is reported herein. When examined as anode materials for lithium‐ion batteries, the as‐prepared porous NiCoO₂ nanofibers demonstrate superior lithium storage properties, delivering a high discharge capacity of 945 mA h g^?1 after 140 cycles at 100 mA g^?1 and a high rate capacity of 523 mA h g^?1 at 2000 mA g^?1. This excellent electrochemical performance could be ascribed to the novel hierarchical nanoparticle‐nanofiber assembly structure, which can not only buffer the volumetric changes upon lithiation/delithiation processes but also provide enlarged surface sites for lithium storage and facilitate the charge/electrolyte diffusion. Notably, a facile synthetic strategy for fabrication of ternary/mixed metal oxides with 1D nanostructures, which is promising for energy‐related applications, is provided.     

A facile and mild Pd-catalyzed one-pot process for direct hydrodeoxygenation (HDO) phenols to arenes through a ArOSO2F intermediates transformation

A practical one-pot process for hydrodeoxygenation (HDO) of phenolic derivatives to their corresponding arenes was developed. This method provided a facile route to upgrading bio-oil. The substrate scope of this protocol was wide, complicated and multi-phenolic compounds were also smoothly hydrodeoxygenated to their corresponding arenes.     

Efficient scavenging of uranium (VI) using porous hexagonal boron nitride by a combined process of surface adsorption and induced precipitation crystallization

An ammonium/hydroxyl-enriched p-BN microrods were synthesized and the adsorption behavior of uranyl on p-BN was systematically studied. The adsorption kinetic and isotherm studies revealed the adsorption behavior is independent on electrostatic attraction or chemisorption. The results demonstrate uranyl hydrolyzed precipitated crystals are formed on the surface of p-BN at an optimized pH of 2.86 and the maximum adsorption capacity can reach 413 mg g^?1 at T?=?303 K. A hypothetical adsorption mechanism with a combination of surface adsorption and induced precipitation crystallization was proposed.

     

Frequency-Domain Fluorescence Lifetime Measurements via Frequency Segmentation and Recombination as Applied to Pyrene with Dissolved Humic Materials

In this study, the association behavior of pyrene with different dissolved humic materials (DHM) was investigated utilizing the recently developed segmented frequency-domain fluorescence lifetime method. The humic materials involved in this study consisted of three commercially available International Humic Substances Society standards (Suwannee River fulvic acid reference, SRFAR, Leonardite humic acid standard, LHAS, and Florida peat humic acid standard, FPHAS), the peat derived Amherst humic acid (AHA), and a chemically bleached Amherst humic acid (BAHA). It was found that the three commercial humic materials displayed three lifetime components, while both Amherst samples displayed only two lifetime components. In addition, it was found that the chemical bleaching procedure preferentially removed red wavelength emitting fluorophores from AHA. In regards to pyrene association with the DHM, different behavior was found for all commercially available humics, while AHA and BAHA, which displayed strikingly similar behavior in terms of fluorescence lifetimes. It was also found that there was an enhancement of pyrene’s measured lifetime (combined with a decrease in pyrene emission) in the presence of FPHAS. The implications of this long lifetime are discussed in terms of (1) quenching mechanism and (2) use of the fluorescence quenching method used to determine the binding of compounds to DHM. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis and characterization of binaphthalene-2,2′-diamine-functionalized gold nanoparticles

Gold nanoparticles 1.7 and 54 nm in diameters have been synthesized and functionalized successfully with their surfaces engineered using two atropisomeric capping ligands, 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (BINAP) and 1,1′-binaphthalene-2,2′-diamine (DABN), respectively. A systematic study to compare the two different gold nanoparticles is presented using multiple material characterization techniques. It was found that the two systems show different capping mechanism and hence differ in their intrinsic core and surface properties. The compound BINAP plays only surface capping agent and stabilizes the gold nanoparticles, resulting in small particle size and suppressed surface plasmon resonance absorption at 520 nm. The DABN capping ligand is different from BINAP and acts as both reducing and capping agent, causing the reduction of Au (III) to Au (0). The nucleation growth of the gold core occurs in accordance with the polymerization-passivation process by DABN, resulting in a big particle size of 20 nm. A strong surface plasmon resonance band shows a maximum peak at 564 nm, consistent with the Au core size. The simultaneous oxidative polymerization of DABN and the induced metal reduction process lead to the formation of gold nanoparticles encapsulated by a mixture of DABN oligomers or polymers.

Open image in new window

Graphical abstract ?

     

Fabrication of Conductive Polypyrrole Doped Chitosan Thin Film for Sensitive Detection of Sulfite in Real Food and Biological Samples

In this study, we reported electrochemical synthesis of conductive polypyrrole‐chitosan (PPY‐CHI) thin film for sensitive detection of sulfite in real samples. The synthesized PPY‐CHI film was characterized in terms of surface morphology, optical property, binding energy, conductivity and electrochemical properties. The synthesized copolymeric PPY‐CHI film displayed good electrocatalytic behaviour towards oxidation of sulfite. The synthesized PPY‐CHI film was used for sulfite detection using differential pulse voltammetric technique with detection limit, sensitivity and linearity of 0.21 μM (S/N=3), 15.28 μA μM cm^?2 and 50–1100 μM respectively. In addition, the current responses of PPY‐CHI film towards sulfite were repeatable, reproducible response and unaffected by selected electroactive interferents. Finally, the synthesized PPY‐CHI was successfully and satisfactorily applied for determination of sulfite in real food and biological samples. The results obtained from this study highly placed PPY‐CHI film as a promising sensor for sensitive and accurate detection of sulfite in food and biological samples for human health protection.