Dendritic nanostructures of silver: facile synthesis, structural characterizations, and sensing applications

Silver nanodendrites are synthesized by a simple surfactant-free method using a suspension of zinc microparticles as a heterogeneous reducing agent. Structural characterizations suggest the preferential growth along 100 and 111 directions by oriented attachment of silver nanocrystals in the diffusion limit, leading to the formation of silver nanodendrites 20-30 nm in stem and branch diameter and 5-50 microm in length. Surface-enhanced Raman scattering studies show that the silver nanodentrites give an intensive and enhanced Raman scattering when pyridine was used as a probing molecule. We have also demonstrated that the silver nanodendrites increase the sensitivity of an electrochemical glucose biosensor by as much as 1-2 orders of magnitude.     

Polyaniline nanofibers: facile synthesis and chemical sensors

Polyaniline nanofibers with uniform diameters between 30 and 50 nm can be made in bulk quantities through a facile aqueous/organic interfacial polymerization method at ambient conditions. The nanofibers have lengths varying from 500 nm to several micrometers and form interconnected networks. Thin films made of the nanofibers have superior performance in both sensitivity and time response to vapors of acid (HCl) and base (NH3).     

Turning waste into wealth: facile and green synthesis of carbon nanodots from pollutants and applications to bioimaging

In an effort to turn waste into wealth, Reactive Red 2 (RR2), a common and refractory organic pollutant in industrial wastewater, has been employed for the first time as a precursor to synthesize carbon nanodots (CNDs) by a facile, green and low-cost route, without utilization of any strong acids or other oxidizers. The detailed characterizations have confirmed that the synthesized CNDs exhibit good water dispersibility, with a mean particle size of 2.43 nm and thickness of 1–3 layers. Importantly, the excellent fluorescence properties and much reduced biotoxicity of the CNDs confer its potential applications in further biological imaging, which has been successfully verified in both in vitro (cell culture) and in vivo (zebrafish) model systems. Thus, it is demonstrated that the synthesized CNDs exhibit nice biocompatibility and fluorescence properties for bioimaging. This work not only provides a novel economical and environmentally friendly approach in recycling a chemical pollutant, but also greatly promotes the potential application of CNDs in biological imaging.

The pollutant reactive red 2 was employed to synthesize fluorescent carbon nanodots allowing biological imaging in vitro and in vivo.     

Chemistry of siloles. The reactions of siloles with organolithium reagents

The chemical behaviour of siloles toward various organolithium reagents in THF has been investigated. The reaction of 1-methyl-1-(trimethylsilyl)-, 1-phenyl-1-(trimethylsilyl)- and 1,1-bis(trimethylsilyl)dibenzosilole (I, II and III) with a large excess of an alkyllithium such as methyllithium or butyllithium afforded 1,1-dialkyldibenzosiloles in quantitative yields. Treatment of I with an excess of phenyllithium gave a mixture of 1-methyl-1-phenyl- and 1,1-diphenyldibenzosilole quantitatively, while with an excess of tert-butyllithium, I afforded 1,1-dimethyl- and 1-tert-butyl-1-methyldibenzosilole in low yield. Similar treatment of I and II with 1 equiv. of methyl- or butyl-lithium yielded a mixture of the corresponding mono- and dialkyl-substituted dibenzosiloles. 1-Methyl-3,4-diphenyl-1,2,5-tris(trimehylsilyl)silole reacted with methyllithium in THF to give 1,1-dimethyl-3,4-diphenyl-2,2,5-tris(trimethylsilyl) silole. Similarly, both 2,4-diphenyl-1,1,3,5-tetrakis(trimethylsilyl)silole and 4,5-diphenyl-1,1,2,3-tetrakis(trimethylsilyl)silole with methyllithium afforded two isomers of 1-methyl-2,4-diphenyl-1,2,3,5-tetrakis(trimethylsilyl)-1-silacyclopent-3-ene in a ratio of 3 : 2 in high yields.     

A facile synthesis of cyclotriveratrylene

Cyclotriveratrylene (CTV) can be readily synthesized by chloromethylation or bromomethylation of dimethoxybenzene with halomethyloctyl ether in the presence of SnCl₄. The reaction provides the trimer exclusively and in high yield. Recrystallizations from benzene or CHCl₃ yielded the solvent inclusion complexes and did not remove other inclusion impurities. Flash chromatography on silica yielded the pure CTV.¹³C NMR shows only five signals and no impurities.     

A facile synthesis of N-sulfinylaldimines

A simple and efficient procedure for the synthesis of N-sulfinylaldimines (sulfinimines) from sulfinamides and aldehydes is described. The reaction was carried out in the presence of t-BuOK or NaOH. The method is applicable for the synthesis of optically active sulfinimines.     

A facile synthesis of muscimol

The psychoactive isoxazole muscimol $\text{10}$ has been synthesized in three steps from propargyl chloride.     

A facile synthesis of cyclononatripyrroles

A facile synthesis of a functionalized cyclononatripyrrole derivative is described. It involves the iodine-catalyzed cyclotrimerization of ethyl 3,3-dimethyl-5,7-dihydro[1,3]dioxepino[5,6-c]pyrrole-6-carboxylate in methanol. The product obtained in this way exists solely in the crown conformation typical of cyclononatripyrroles. However, in contrast to previously reported compounds of this class, it possesses three labile methoxymethyl arms that can be further functionalized under acidic conditions.     

A facile synthesis of polyfoluoroalkyl-lactonization

2(-Benzoxazolyl substituted cyclopropane derivatives were synthesized in the yield of 73-89% from the reaction of telluronium ylides with chalcones.     

A facile synthesis of cyanophenothiazines

A one-pot synthesis of 1, 3 and 4-cyanophenothiazines and a two-step approach to 2-cyanoisomer have been developed. The condensation of 2-aminobenzenethiol and 2,3 or 3,4-dihalogenobenzonitriles followed by Smiles rearrangement or by intramolecular aromatic substitution gave the desired ring systmes.     

A facile synthesis of ulicyclamide

Ulicyclamide (1), a cytotoxic cyclic peptide from a marine tunicate, has been efficiently synthesized by the solid-phase method using diethyl phosphorocyanidate for the coupling and trimethylsilyl triflate for the final deprotection.     

Ultrasmall Pd nanoclusters: facile synthesis and versatile catalytic application

A simple and efficient method for the synthesis of ultrasmall Pd nanoclusters(NCs) has been developed. The as-obtained Pd NCs displayed uniform size with an average diameter of 1.8±0.2 nm. The ultrasmall Pd NCs and carbon nanotubes(CNTs)-supported Pd NCs also showed outstanding catalytic activity for nitrobenzene reduction and Suzuki coupling reactions. Notably, the reactions were conducted under mild conditions with high yield and selectivity.     

Graphene-CdS nanocomposites: facile one-step synthesis and enhanced photoelectrochemical cytosensing

Graphene-CdS (GR-CdS) nanocomposites were prepared in a one-step synthesis in aqueous solution. The synthetic approach was simple and fast, and it may be extended for the synthesis of other GR-metal-sulfide nanocomposites. The as-prepared GR-CdS nanocomposite films inherited the excellent electron-transport properties of GR. In addition, the heteronanostructure of the GR-CdS nanocomposites facilitated the spatial separation of the charge carriers, thus resulting in enhanced photocurrent intensity, which makes it a promising candidate for photoelectrochemical applications. This strategy was used for the fabrication of an advanced photoelectrochemical cytosensor, based on these GR-CdS nanocomposites, by using a layer-by-layer assembly process. This photoelectrochemical cytosensor showed a good photoelectronic effect and cell-capture ability, and had a wide linear range and low detection limit for Hela cells. The as-synthesized GR-CdS nanocomposites exhibited obviously enhanced photovoltaic properties, which could be an efficient platform for many other high-performance photovoltaic devices.     

Architecture-adapted raspberry-like gold@polyaniline particles: facile synthesis and catalytic activity

A facile route was introduced to generate uniform raspberry-like gold@polyaniline (AuNP@PANI) particles in the presence of sodium dodecylsulfate (SDS). The surfactant SDS played an important role in both generating a uniform structure and stabilizing these particles. Upon addition of low-molecular weight organics, the regulation on the gold architecture was realized from a compact to stretched configuration owing to the change of surface tension and a possible swell process. The catalytic activity of the raspberry-like AuNP@PANI was investigated using the reduction of 4-nitrophenol by NaBH₄ and electrocatalytic oxidation of glucose as model reactions. It was found that the AuNP@PANI particles with the most stretched architecture presented the highest catalytic activity owing to their largest contact surface to the reactants.