"ON-OFF" switching of europium complex luminescence coupled with a ligand redox process

A triarylamine-functionalized terpyridine ligand formed a highly coordinated complex with europium tris(β-diketonate), which displayed reversible 'ON-OFF' luminescence switching coupled with a ligand redox process of triarylamine/triarylaminium cations.     

The body-centered cubic structure of methyllithium tetramer crystal: staggered methyl conformation by electrostatic stabilization via intratetramer multipolarization

The methyllithium tetramer (CH3Li)4 structure in the bcc crystal has been theoretically optimized with the use of density functional theory calculations under the periodic boundary condition. The X-ray structure shows that the methyl-group conformation in tetramer in crystal takes the staggered form rather than the eclipsed form that is taken in the isolated tetramer, i.e., the crystal packing effect, and this has been reproduced for the first time. It is concluded that the staggered form is advantageous in crystal, as a whole, due to the larger electrostatic stabilization via the induced intratetramer multipolarization, although it should cause, simultaneously, smaller destabilization in intratetramer electronic energy.     

Mercuric triflate-catalyzed reaction of propargyl acetates with water leading vinyl ketones

[reaction: see text]. Reaction of propargyl acetate with water catalyzed by Hg(OTf)2 afforded vinyl ketone as the major product along with a dimeric vinyl mercuric product and normal hydration products in small amounts. The reaction is an alternative to the Meyer-Schuster and Rupe rearrangement applicable to primary alcohols, although the mechanism is entirely different.     

Croissamide,a proline-rich cyclic peptide with an N-prenylated tryptophan from a marine cyanobacterium Symploca sp.

Croissamide, a proline-rich cyclic peptide that contains an N-prenylated tryptophan, was isolated from a marine cyanobacterium Symploca sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on chiral HPLC analyses of acid hydrolysates.     

Determination of gallium in biological materials by electrothermal atomic absorption spectrometry

In this determination of gallium, the condition of the graphite tubes influences the peak height. Common acids and salts seriously affect the results, but in the presence of EDTA, interferences of nitric and hydrochloric acids are suppressed completely, and interferences of phosphoric acid and some salts are suppressed partly. To compensate for the effects, a standard addition procedure is proposed, and is applied to healthy and tumor.bearing mice. A linear calibration is obtained for 0.12–12 ng Ga in 50-μl aliquots. The method is applied to tissues and body fluids with good recovery and precision.     

Degradation of estrogen conjugates using titanium dioxide as a photocatalyst.

Estrogen conjugates (estradiol-3-glucuronide, -17-glucuronide, estrone-glucuronide and -sulfate) were subjected to photodegradation using titanium dioxide immobilized on glass beads as a catalyst. Their time courses were measured by HPLC and compared with those of the unconjugated estrogens. Estradiol, its 17-glucuronide and estrone, which have an unconjugated phenolic hydroxy group at the C-3 position, were almost completely degraded by UV irradiation within 4 h. On the other hand, significant amounts of estradiol- and estrone-3-glucuronide (ca. 20%, 25%) and estrone sulfate (ca. 90%), which were conjugated at the 3-hydroxy group, remained after a 6.5 h irradiation. These results supported the hypothesis that the photodegradation of estrogens was initiated at the phenolic hydroxy group.     

Coulometric Anodic Stripping Voltammetry of Lead at Copper Column Electrode

A flow coulometric electroanalytical system using a copper column electrode with a copper wire inserted into a Nafion tube was developed to determine Pb(II) content based on anodic stripping voltammetry. The electrolysis efficiency of 5 μM Pb(II) was evaluated to be 100.4±4.5 % (n=5) when the length of the copper wire and flow rate of the Pb(II) solution were 50 cm and 0.1 mL min⁻¹, respectively. The amount of electricity due to the re-oxidation of Pb electrodeposited at the copper column electrode was proportional to the concentration of Pb(II) in the range between 0.1 to 100 μM, and the limit of detection for Pb(II) was 0.8 μM for a deposition time of 15 min. Interference from the presence of Cd(II) could be avoided and the selective determination of Pb(II) was successfully achieved by adjustment of the electrodeposition potential.     

Sorption and desorption experiments using stable cesium: considerations for radiocesium retention by fresh plant residues in Fukushima forest soils

Journal of Radioanalytical and Nuclear Chemistry - We conducted sorption experiments with stable cesium (133Cs) solution in different organic matter samples, aiming to understand the sorption of...