Dialkylaminoacetonitrile derivatives as amide synthons. A one-pot preparation of heteroaryl amides via a strategy of sequential SNAr substitution and oxidation

Dialkylamino acetonitrile derivatives were utilized as alternative to cyanohydrin synthons for preparation of the corresponding heteroaryl dialkyl amides via a strategy of sequential base-mediated coupling and oxidation. The most advantageous oxidant, NiO(2)-H(2)O, can readily oxidize 2-substituted aminoacetonitriles to the corresponding amides under both basic and neutral conditions by forming cyanohydrins in situ.     

Synthesis and electronic properties of donor-acceptor pi-conjugated siloles

An efficient method is presented for the synthesis of novel donor-acceptor silole chromophores through selective monohalogenation of 2,5-dimetallosiloles followed by Negishi alkyne cross-coupling reactions. The electronic properties and crystal packing of these new siloles can be controlled through judicious combinations of peripheral functional groups.     

Self-assembly of CuS nanoparticles to solid,hollow, spherical and tubular structures in a simple aqueous-phase reaction

We report fabrication of CuS particles with solid, hollow, spherical and tubular structures in a simple aqueous system under microwave irradiation, employing CuSO₄ and Na₂S₂O₃ as the starting materials without assistance of any surfactant or template. Energy-dispersive X-ray analysis and an X-ray powder diffraction pattern proved that the product is hexagonal CuS phase. The morphologies of the product were observed by scanning electron microscopy and transmission electron microscopy. Some factors affecting the morphologies of the product are discussed. PACS 81.05.Hd; 81.07.Bc; 81.16.Be; 81.16.Dn; 81.20.Ka     

Phase-matched high-order harmonics by interaction of Ar atoms with high-repetition-rate low-energy femtosecond laser pulses

High-order harmonics are generated by coherent interaction of an intense laser and atoms or molecules[1]. With the development of the intense ultrashort pulse laser, the research of high-order harmonic generation has reached the water-window in spectral region[2] and subfemtosecond in time domain[3]. Especially, the generation and application of subfemtosecond pulse led the study of high-order harmonic generation into a completely new world[4, 5]. It has made the study of ultrafast science fro…     

Capacitive sensors using electropolymerized o-phenylenediamine film doped with ion-pair complex as selective elements for the determination of pentoxyverine

A capacitive sensing method based on electropolymerized o-phenylenediamine film doped with pentoxyverine ion-pair complex as selective element was successfully developed for the determination of pentoxyverine. Ion-pair complex, pentoxyverine-tetraphenylborate or pentoxyverine-picrolonate, was embedded in electropolymerized o-phenylenediamine film by electropolymerizing technique. The effects of working frequency and test solution pH on the detection of pentoxyverine were investigated in detail and optimized. For the sensor modified with pentoxyverine-tetraphenylborate, calibration curve was linear over the concentration range of 5.0×10⁻⁷ to 1.0×10⁻⁴ M with a detection limit of 1.0×10⁻⁷ M at pH 7. The proposed sensor exhibited high selectivity and sensitivity to pentoxyverine. The results in sample analysis confirmed the usefulness of the proposed ISC sensor for quantitative analysis, and also indicated that this method might find applications in the assay of other drugs.     

Zinc oxide quantum rods

Nanoscale zinc oxide (ZnO) rods of diameters close to the Bohr-exciton radius ( approximately 2 nm) can be prepared from a simple acetate precursor, resulting in ligand-capped rods of ZnO, highly dispersible in nonpolar solvents. Zinc oxide, ZnO, is a wide band-gap semiconductor with applications in blue/ultraviolet (UV) optoelectronic devices and piezoelectric devices. We observe self-assembly into uniform stacks of nanorods aligned parallel to each other with respect to the long axis, and photoluminescence measurements provide evidence for one-dimensional quantum confinement.     

Direct optical resolution of the enantiomers of novel chiral tetrahedral metal clusters by HPLC on a cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase

The enantioseparation of seven novel chiral transition metal tetrahedral clusters has been achieved for the first time on cellulose derivatized with tris(3,5-dimethylphenylcarbamate) (CDMPC) as chiral stationary phase (CSP) and hexane containing different alcohols as modifiers as mobile phases. The effect of mobile-phase composition on enantioselectivity was studied, and the effect of structural variation of the solutes on their enantioseparation was also investigated. It was found that both the metal in the tetrahedral core and the ligand coordinated to the atom in the tetrahedral core had significant effects on the chromatographic behavior of the analytes.     

On the Almost Intersections of Transient Brownian Motions

Let {B ₁ ^d (t)} and {B ^d ₂(t)} be independent Brownian motions in R ^d starting from 0 and nx respectively, and let w ^d _i (a,b) ={xR ^d : B ^d _i (t)=x for some t(a,b)}, i=1,2. Asymptotic expressions as n for the probability of dist(w ^d ₁(n ² t ₁, n ² t ₂), w ₂ ^d (0,n ² t ₃))1 with d4, respectively for the probability of dist(w ₁ ⁴(n ² t ₁,n ² t ₂),w ₂ ⁴(0,n ² t ₃))1 are obtained. As an application, an improvement of a result due to M. Aizenman concerning the intersections of Wiener sausages in R ⁴ is presented.