Development of determination method of trace nickel in natural water by ID-oxygen added nitrogen-MIP-MS with direct measurement of liquid–liquid extracted organic phase

This work introduces the development of a novel determination method of trace nickel (ng l^–1 level) in natural water samples. Nickel in the water samples is liquid–liquid extracted into methyl isobutyl ketone (MIBK) as nickel-diethyldithiocarbamate (DDTC) complex, and isotope dilution-oxygen added nitrogen-microwave induced plasma mass spectrometry (ID-oxygen added nitrogen-MIP-MS) is conducted by direct measurement of the liquid–liquid extracted organic MIBK phase. The accuracy of the proposed method was confirmed by analysing certified reference materials (NRC NASS-5 seawater, NRC SLRS-3 riverine water and NRC SLRS-4 river water), and the analytical results obtained were in good agreement with the certified values. The detection limit for nickel is 1.3?ng?l^?1 when the water sample is 50 times concentrated. The precision as RSD is <4%. The proposed method was applied to clarify the concentration-depth vertical profiles of nickel in Lake Mashu, Japan, as the Baseline Station of the United Nations GEMS/Water (Global Environment Monitoring System/Water) Programme.     

Solid state-specific and chiral lattice-controlled asymmetric photoisomerization of 3-substituted propyl cobalt complexes, and direct observation of the intermediate complex

Solid state-specific and chiral lattice-controlled asymmetric photoisomerization of 3-cyanopropyl cobaloxime complexes coordinated with chiral axial ligand, 1a-h, was found to occur with moderate to relatively high enantioselectivities (∼91%ee), even though the reaction proceeds through radical species. The enantioselectivities at a lower temperature (−78 °C) are extremely enhanced as compared to those at room temperature, in most cases.The configuration of the major enantiomer of the isomerized product is predictable from the shape of the reaction cavity, drawn based on the crystal structure of the starting material. The structure (including absolute configuration) of the intermediate 2-cyanopropyl complex was directly observed by X-ray crystallographic analyses of a single-crystal-to-single-crystal reaction of (S)-1-cyclohexylethylamine-coordinated 3-cyanopropyl cobaloxime, 1e.     

Total synthesis of (+/-)-trachyspic acid and determination of the relative configuration

[reaction: see text] The first total synthesis of (+/-)-trachyspic acid, a tumor cell heparanase inhibitor, was accomplished based on Cr(II)/Ni(II)-mediated reaction of the aldehyde containing the citric acid moiety and the long-chain triflate, and the relative configuration of this natural product was determined.     

PARTIAL CHARACTERIZATION and LIGHT-INDUCED REGULATION OF GTP-BINDING PROTEINS IN Lemna paucicostata

Binding of GTP-binding proteins with [³⁵S]GTP7S in the extract containing membrane components of Lemna paucicostata 441 was inhibited by red or far red light by 20 to 25%, but blue light showed no or little effect. The plant used for the preparation of the extract was subjected to single darkness for 8 h, as both red and far red light inhibit flowering. The extract treated with 1% Lubrol was fractionated by gel filtration. Four species of GTP-binding proteins, GL1, GL2, GL3 and GL4 were detected with Km values 3, 7, 80 and 4 n M , respectively. GL1, GL2 and GL3 were ADP-ribosylated by pertussis toxin. The extract activated by [³⁵S]GTP-γS in darkness, under red light or under far red light was treated with 1% Lubrol and subsequent gel filtration of the extracts made it possible to detect GTP-binding protein with a small molecular weight only in an extract labeled in darkness. The reduction in the molecular weight of GTP-binding protein from the larger molecule associated with the binding of [³⁵S]GTPγS was confirmed by rechromatography of the larger molecule activated by [³⁵S]GTPγS in darkness. The binding of GL2 and/or GL3 with [³⁵S]GTPγS was suggested to be inhibited by red or far red light.     

Catalytic asymmetric synthesis of vicinal diamine derivatives through enantioselective N-allylation using chiral pi-allyl Pd-catalyst

[reaction: see text] N-monoallylation of meso-vicinal diamine bistrisylamides using a chiral pi-allyl-Pd catalyst proceeded in an enantioselective manner (up to 90% ee) to give desymmetrization products in good yields. The product was converted to the known sigma-receptor agonist in short steps. In addition, the present catalytic asymmetric N-allylation was applied to kinetic resolution of racemic-diamide.     

Cycloadditions of 1-substituted 1,3-butadienes with 4- or 3-substituted 2(1H)-quinolones acting as dienophiles

Cycloadditions of 1,3-butadiene derivatives having an electron-rich group at the 1-position with 4- or 3-substituted 2(1H)-quinolones were carried out to give the richly functionalized phenanthridines under both atmospheric and high pressure conditions. Furthermore, the reactivity of 4- or 3-substituted 2(1H)-quinolones acting as a dienophile with 1-substituted dienes was examined using MO calculation.     

Sensitive analysis of alkyl alcohols as decomposition products of alkyl nitrites in human whole blood and urine by headspace capillary GC with cryogenic oven trapping

The abuse of alkyl nitrites is becoming a serious social problem worldwide. In this report, a simple and sensitive method is presented for the determination of n-butyl alcohol, isobutyl alcohol, and isoamyl alcohol as decomposition products of alkyl nitrites in human whole blood and urine samples using capillary gas chromatography (GC) with cryogenic oven trapping. After heating a whole blood or urine sample containing each alkyl alcohol and t-butyl alcohol [the internal standard (IS)] in a 7-mL vial at 55 degrees C for 15 min, 5 mL of the headspace vapor is drawn into a gas-tight syringe and injected into a GC inlet port. The vapor is introduced into an Rtx-BAC2 medium-bore capillary column in the splitless mode at 0 degrees C oven temperature in order to trap the entire analytes, and then the oven temperature is programmed up to 240 degrees C for the GC measurements by flame ionization detection. These conditions give sharp peaks for each compound and the IS and low background noise for whole blood or urine samples. The detection limits of the analytes are 10 ng/mL for whole blood and 5 ng/mL for urine. Linearity and precision are also tested to confirm the reliability of this method. Isobutyl alcohol and methemoglobin could be determined from the whole blood samples of three male volunteers who had sniffed isobutyl nitrite.     

Kinetically stabilized dibenzoborole as an electron-accepting building unit

A synthetic route to a dibenzoborole, kinetically stabilized by the 2,4,6-tri-tert-butylphenyl group, was developed, and a series of pi-extended derivatives were synthesized, which show orange-red emissions and stable electrochemical redox properties.