Intermolecular interactions of a size‐expanded guanine analogue with gold nanoclusters

The interactions between a size‐expanded Guanine analogue x‐Guanine (xG) and gold nanoclusters, Au_n (n = 2, 4, 6, and 8), were studied theoretically using density functional theory. Geometries of neutral complexes were optimized using the B3LYP functional with the 6‐31+G(d,p) basis set for xG and the LANL2DZ basis set for gold clusters. The binding modes, interaction strength, and the charge‐transfer properties of different Au_n‐xG complexes were investigated. Natural population analysis was performed for natural bond order charges. It was found that gold nanoclusters form stable complexes with xG and these binding results in a substantial amount of electronic charge being transferred from xG to the gold clusters. The vertical first ionization potential, electron affinity, Fermi Level, and the HOMO–LUMO gap of xG and its complexes with gold nanoclusters were also analyzed. © 2013 Wiley Periodicals, Inc.     

Facile synthesis of a porous network-like silver film for electrocatalytic detection of nitrate

We have developed a method for in-situ construction of a porous network-like silver film on the surface of a glassy carbon electrode (GCE). It is based on a galvanic replacement reaction where a layer of copper nanoparticles is first electrodeposited as a sacrificial template. The silver film formed possesses a porous network-like structure and consists of an assembly of numerous nanoparticles with an average size of 200 nm. The electrode displays excellent electrocatalytic activity, good stability, and fast response (within 2 s) toward the reduction of nitrate at a working potential of −0.9 V. The catalytic currents linearly increase with the nitrate concentrations in the range of 0.08–6.52 mM, with a detection limit of 3.5 μM (S/N = 3) and a repeatability of 3.4 % (n = 5).

A facile method was developed for in situ construction of a porous network-like Ag film on a glassy carbon electrode by a galvanic replacement reaction, where a layer of Cu nanoparticles previously electrodeposited as a sacrificial template. Thus-formed Ag film displays excellent electrocatalytic activity, good stability, and fast response (within 2 s) toward nitrate reduction.

     

Synthesis of gold nanoparticles on the surface of pyrolytic graphite using penicillin as a stabilizing reagent and the catalytic oxidation of α-naphthylamine

Electrochemical synthesis of gold nanoparticles on the surface of pyrolytic graphite using penicillin as a stabilizing reagent was proposed. The gold nanoparticles were characterized by scanning electron microscopy, cyclic voltammetry, IR spectra, UV spectra, and powder X-ray diffraction spectra. The electro-chemical catalysis of penicillin for α-naphthylamine was demonstrated.     

Gold-nanoparticle on the surface of L-cysteine modified gold electrode and its application

A sensor based on gold nanoparticle on the surface of L-cysteine modified gold electrode is prepared. Electrochemical behavior of dopamine hydrochloride is investigated. The linear relation between peak current of dopamine hydrochloride and scan speed in the range of 10 to 1000 mV s^?1 indicates that a diffusion-adsorption controls the process. The linearity range is 1.05 × 10^?5–7.38 × 10^?4 M with detection limit of 1.05 × 10^?6 M. The recoveries were in the range from 99.8 to 101.5% with relative standard deviations of 1.3 ～ 2.3% (n = 6). The modified electrode under ambient conditions over a period of 2 weeks has an excellent repeatability and reproducibility.     

Efficient One-Pot Synthesis of Tetrahydrobenzo[c]xanthene-1,11-dione Derivatives Under Microwave Irradiation

An efficient one-pot condensation of 4-hydroxylcoumarin, aromatic aldehydes, and 5,5-dimethylcyclohexane-1,3-dione has been achieved with molecular iodine as a catalyst via conventional heating and microwave irradiation techniques, and thus a variety of new tetrahydrobenzo[c]xanthene-1,11-dione derivatives were prepared in good yields.     

Study on the “Tin-Ene” reaction of α-bromoacetophenone and metallic tin with aldehydes

β-hydroxy ketones were obtained in good yields by the “tin-ene” reactions of α-bromoacetophenone and metallic tin with aldehydes.     

Facile and Green Method for the Synthesis of β-Aminoketone Derivatives in Aqueous Media

Three-component reaction of aromatic aldehyde, 2-naphthalenamine, and 1,2-diphenylethanone in aqueous media catalyzed by triethylbenzylammonium chloride (TEBAC) at 90 °C gave 3-aryl-3-(naphthalen-2-ylamino)-1,2-diphenylpropan-1-one derivatives. The enol form of 1,2-diphenylethanone was tentatively proposed to participate in the formation of the products. Compared with previous methods, this three-component reaction has the advantages of green solvent, good yields, and operational simplicity.     

Facile Method for One-Step Synthesis of 2,4,5-Triarylimidazoles Under Catalyst-Free,Solvent-Free,and Microwave-Irradiation Conditions

A green and efficient method for the synthesis of 2,4,5-triarylimidazoles by one-step condensation reaction of benzil, aromatic aldehyde, and ammonium acetate under catalyst-free, solvent-free, and microwave-irradiation conditions is reported. This method had many dramatic advantages, such as the short reaction time (3–5 min), good yields (80–99%), environmental friendliness, and convenient operation.     

A Short Synthesis of 1-Vinyluracil and 1-Vinylthymine

1-Vinyluracil and 1-vinylthymine, monomers for nucleic acid bases attached functional polymers, were synthesized for the first time from uracil and thymine in 3 steps in 54% and 50% overall yields using the Mitsunobu reactions of 2a and 2b with 2-chloroethanol as a key step.     

Facile Synthesis of 5‐Benzylidene Rhodamine Derivatives under Microwave Irradiation

A series of 5‐benzylidenerhodamine derivatives were synthesized by the cross‐aldol condensation of an aromatic aldehyde with rhodamine or rhodamine acetic acid in sodium acetate/acetic acid under microwave irradiation. The reaction was completed in 8–20 min with 63–94% yields and was environmentally benign with easy workup.