Optical properties of Au–Ag core–shell nanorods on glass and ITO substrates

Gold-silver core–shell nanorods were deposited on glass and ITO plates. SEM observations indicated that some of these nanorods were standing on the ITO plate. The extinction spectra of the plates were measured by varying the angles of incidence of p-polarized monitor light. Deconvolution of these spectra gave six bands in the visible region. The dependence of the peak intensities on the incident angles indicated that the bands at 390 and 420 nm originated from surface plasmon bands in the transverse direction of the nanorods.     

An application of plastic microchannel-microheater chips to a thermal synthetic reaction.

Polystyrol microchannel-microheater chips were fabricated on the basis of imprinting and photolithography techniques. The solution (i.e., methanol) temperature in the vicinity of the microheater (width = 100 or 200 microm and length = 100 microm) integrated in the channel (width = 100 microm and depth = 20 microm) was evaluated on the basis of the temperature-dependent fluorescence lifetime of Rhodamine B as a function of a flow rate and the voltage applied to the heater. The study demonstrated that the fabricated chip acted certainly as a microheater. The chip was then applied to the thermal reaction between benzaldehyde and malononitrile in methanol. Under optimum conditions, benzilidenemalononitrile as the product of the reaction was obtained in a 96% yield with the reaction time of 84 s.     

Simple detection of trace Pb2+ by enrichment on cerium phosphate membrane filter coupled with color signaling

A Pb(2+) selective membrane filter was fabricated from the fibrous CeO(H(2)PO(4))(2).2H(2)O (CeP) crystals by blending with cellulose fiber. Enrichment of ppb level of Pb(2+) was achieved simply by filtration of aqueous sample solution through the membrane filter. Pb(2+) was strongly retained on the membrane filter by accommodation into the interlayer gallery of a CeP crystal. Visual detection of the enriched Pb(2+) was achieved by subsequent color signaling as PbS deposit upon treatment of the membrane filter with 3% Na(2)S solution. The analytical procedure and sample treatment conditions were optimized with respect to pH of the sample solution, filtration rate and masking of interfering ions. Detection of 20 ppb of Pb(2+) was not interfered by the presence of 1000-fold of Ca(2+), Mg(2+), and up to 100-fold of Fe(3+)and Cu(2+) by masking with 1 x 10(-3) mol dm(-3) of iminodiacetic acid (IDA). Most anions including phosphate (20 000 times) did not interfere with the determination of Pb(2+). The present simple method was applied to the determination of Pb(2+) in real samples like mine valley water.     

Revision and confirmation of the regiochemistry of isoxazoles derived from methyl oleanonate and lanost-8-en-3-one. Synthesis of a new lanostane triterpenoid with a cyano-enone functionality in ring A

It was previously reported that methyl oleanonate (5) and lanost-8-en-3-one (10) give predominantly [3,2-c]isoxazoles. On the contrary, we have confirmed that both compounds 5 and 10 do not give [3,2-c]isoxazoles but rather afford regioselectively [2,3-d]isoxazoles in good yields. Consequently, a new lanostane triterpenoid with a cyano-enone functionality in ring A was synthesized in two steps from the corresponding [2,3-d]isoxazole, which is interesting from the perspective of biological activity because lanosterol is the biogenetic precursor of steroids.     

Impurity profiling of ephedrines in methamphetamine by high-performance liquid chromatography

Separation of the enantiomers and diastereomers of ephedrines was investigated for impurity profiling of methamphetamine. We describe a method for the analysis of (1S,2R)-(+)-ephedrine, (1R,2S)-(-)-ephedrine, (1S,2S)-(+)-pseudoephedrine and racemic methylephedrine in bulk methamphetamine by HPLC using two different columns: a phenyl-beta-cyclodextrin-type column and an ODS-type column. The analytes were detected by UV absorbance measurement at 210 nm. As little as 0.05% of each ephedrine in bulk methamphetamine could be determined. In the impurity profiling of methamphetamine, the identification of ephedrines may provide valuable information about the precursor. This method was confirmed to be sufficiently sensitive to identify trace amounts of (1R,2S)-(-)-ephedrine and (1S,2S)-(+)-pseudoephedrine in bulk methamphetamine synthesized by the Emde method.     

13C-NMR spectral studies on the distribution of substituents in water-soluble cellulose acetate

The degree of substitution (DS) and distribution of O-acetyl groups of water-soluble cellulose acetate (CA) were investigated by ¹³C-NMR. For this purpose, three different series of CA samples with low DS were prepared by respective homogeneous reaction, i.e., (1) deacetylation of cellulose triacetate (CTA) in acetic acid—water solution (D-series), (2) reaction of CTA with hydrazine (H-series), and (3) acetylation of cellulose with acetic anhydride in a 10% LiCl-dimethylacetamide solution (A-series). It was found that (i) water-soluble CA can be obtained only from D-series products, (ii) the DS value of water-soluble CA ranges from 0.5 to 1.1, (iii) the D-series products exhibit little difference between the relative DS values at C-2, C-3 and C-6 hydroxyl groups, and (iv) the relative DS at C-6 hydroxyl groups is very high compared to those at C-2 and C-3 hydroxyl groups in H- and A-series products. Aqueous solution of water-soluble CA (D-series sample) showed no gel—sol transition, even when the temperature was raised to 95°C. X-ray diffraction observations revealed that the water-soluble D-series samples were essentially noncrystalline, but the water-insoluble A-series samples were crystalline. It was also found that the relative ease of acetylation is C-6 > C-2 > C-3.     

Extraction behavior of Mo and W from H2SO4 and HF/HCl solutions into toluene with Aliquat336: sulfate and fluoride complex formation of Mo and W towards chemical studies of seaborgium (Sg)

Journal of Radioanalytical and Nuclear Chemistry - We have studied extraction behavior of group-6 elements Mo and W to search for suitable conditions for an on-line extraction experiment of their...     

An asymmetric synthesis of (+)-monomorine I

The synthesis of (+)-monomorine I, an indolizidine alkaloid isolated from Monomorium pharaonis, has been achieved. The 2,6-cis-piperidine ring moiety of (+)-monomorine I was constructed using diastereoselective aminopalladation. Chain elongation via cross-metathesis using Hoveyda-Grubbs 2nd catalyst followed by deprotection of the Cbz group and cyclic reductive hydroamination afforded (+)-monomorine I.