Yasuhiko Shibutani

Decisive Factors in the Photoisomerization Behavior of Crowned Spirobenzopyrans: Metal Ion Interaction with Crown Ether and Phenolate Anion Moieties

The influence of metal ion interaction with crowned spirobenzopyrans on the photoisomerization behavior was investigated through the use of various solvents, crowned spirobenzopyrans, and metal ions. Studies on the photoisomerization behavior of crowned spirobenzopyrans in various solvents revealed that solvation of the phenolate anion moiety in the merocyanine form induced photoisomerization back to the spiropyran form, giving rise to negative photochromism. Metal ion interaction with the phenolate anion moiety similarly caused photoisomerization back to the spiropyran form, while that with the crown ether moiety just produced a polar environment and its influence on photoisomerization behavior was dependent on the affinity of the metal ion captured by the crown ether moiety for the phenolate anion. Therefore, photochromic switching of crowned spirobenzopyrans between positive and negative to control the metal ion interaction with the phenolate anion moiety through the crown ether moiety is possible. This finding suggests a molecular design method for crowned spirobenzopyrans showing desired ion-responsive photochromism.

Silver and thallium(I) complexation with dibenzo-16-crown-4

Dibenzo-16-crown-4 (1) indicates high silver and thallium(I) ion selectivity over sodium, potassium, and rubidium ion evaluated from the solvent extraction of metal picrates, while its cation-binding ability is lower than those of dibenzo-18-crown-6 (2) and dibenzo-22-crown-6 (3). Taking account of the highest thallium(I) ion selectivity for 1 obtained from extraction experiments, PVC membrane thallium(I)-selective electrodes based on 1 are prepared. The electrode shows the best potentiometric selectivity coefficients for thallium(I) over potassium and rubidium than those of 2 and 3, and commercially available bis(crown ether)s (4).

Temporal variation of atmospheric polycyclic aromatic hydrocarbon concentrations in PM10 from the Kathmandu Valley and their gas-particle concentrations in winter

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM) with a diameter <10 µm (PM10, 50% cut off) were investigated in the Kathmandu Valley, Nepal, during 2003. In order to understand the dynamics of atmospheric PAHs in winter, the PAH concentrations in total PM and in the gaseous phase were investigated in the valley in December 2005. Total of 45 PAH compounds (∑45PAHs) were analysed by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). In 2003, the ∑45PAH concentrations in PM10 ranged between 4.3 and 89 ng m−3 (annual average; 27 ± 24 ng m−3). The average concentrations of ∑45PAHs in December 2005 were 210 ± 33 ng m−3 in total PM and 430 ± 90 ng m−3 in the gaseous phase. The ∑45PAH concentration in PM accounted for more than 30% of the sum of their particulate and gaseous forms. Phenanthrene (Ph) was the most predominant compound in the gaseous phase, whereas four- to seven-ring PAHs were predominant in total PM. The highest values of ∑45PAHs occurred in the winter and spring. Estimates of emission sources based on diagnostic molecular ratios showed that atmospheric PAHs in the Kathmandu Valley mainly originated from the exhaust gas of diesel engine. In the winter and spring, PAH pollution would be accelerated by the operations of brick kilns and the frequent formation of an atmospherically stable layer in the valley.

Gas–particle concentrations of atmospheric polycyclic aromatic hydrocarbons at an urban and a residential site in Osaka, Japan: Effect of the formation of atmospherically stable layer on their temporal change

A comparative study on atmospheric polycyclic aromatic hydrocarbons (PAHs) in particulate matter and the gaseous phase was performed at an urban and a residential site in Osaka, Japan, during 2005-2006. PAH concentrations at the urban site were found to be approximately twice higher than those at the residential site. At both sites, particulate PAH concentrations increased mainly in winter while the trends of temporal change in gaseous PAH concentrations were not clearly observed. The main sources of PAHs were estimated to be local traffic, e.g., diesel engines with catalytic converter. PAH concentrations did not significantly negatively correlate with ozone concentrations and meteorological parameters. Gas-particle partitioning coefficients of representative PAHs with low molecular weight (LMW) significantly negatively correlated with ambient temperature, showing that temporal change in the LMW PAH concentrations in PM could be attributable to the shift of their gas-particle distribution caused by the change in ambient temperature. For the first time, we studied the effect of the formation of atmospherically stable layer following an increase in PAH concentrations in Japan. At the urban site, PAHs showed a significant positive correlation with potential temperature gradients, indicating that temporal variability in PAH concentrations would be dominantly controlled by the formation of atmospherically stable layer in Osaka area.

High-throughput assay of nitric oxide metabolites in human plasma without deproteinization by lab-on-a-chip electrophoresis using a zwitterionic additive

In order to develop a high-throughput assay for nitric oxide metabolites, nitrite (NO2-) and nitrate (NO3-), in biological fluids, we have investigated the simultaneous determination of them using an electrophoretic lab-on-a-chip (microchip capillary electrophoresis, MCE) technique. In this study, in order to establish an MCE assay process without deproteinization, the addition of a zwitterionic additive into the running buffer to reduce the adsorption of protein onto the surface of channel was investigated. Initially, some zwitterionic additives were investigated by making a comparison of relative standard deviations (RSDs) of the migration times for NO2(-) and NO3(-) on capillary electrophoresis. From the results of our comparison of the RSD values, 2% (w/w) N-cyclohexyl-2-aminoethanesulfonic acid (CHES) was selected. As a result of the application of the running buffer with CHES to the MCE process, the complete separation of NO2(-) and NO3(-) in human plasma without deproteinization was achieved within 1 min. Since the RSD values of the positions of the peaks were less than 2.3%, beneficial reduction effects on MCE were suggested. When we used an internal standard method in order to correct the injection volume, the RSDs of the peak heights and areas were less than 10%, and the correlation coefficients of spiked calibration curves ranging from 0 to 350 microM were 0.999 and 0.997 for NO2(-) and NO3(-), respectively. The limits of detection (S/N=3) were 53 microM for NO2(-) and 41 microM for NO3(-). Moreover, the correlation coefficients in excess of 0.99 between the MCE method and a conventional Griess method were achieved for both NO2(-) and NO3(-). Consequently, the possibility of establishing a high-throughput assay process was obtained by utilizing 2% (w/w) CHES to reduce protein adsorption.

Chemical Introduction of Sugars onto PET Fabrics Using Diamine and Cyanuric Chloride

Polyethylene terephthalate (PET) fibers having reactive cyanuric groups were synthesized by reaction of cyanuric chloride with PET fibers aminolyzed by ethylenediamine. In subsequent reaction with D-glucose, the hygroscopicity of PET fibers was further enhanced. The mechanical strength of PET fibers was not influenced by the reactions other than aminolysis, but their dyeing abilities were greatly affected by each of the reactions. When various sugars other than D-glucose were examined, it was found that reaction with D-maltose imparted the highest hygroscopicity to PET fibers. Interestingly, nonreducing sugars of low reactivity such as D-trehalose could also be made to react with PET fibers using the same methods.

Conformational analysis of 12-crown-3 and sodium ion selectivity of electrodes based on bis(12-crown-3) derivatives with malonate spacers

Abstract A conformational analysis was performed on two crown ethers (12-crown-3 and 12-crown-4) using a combination of semi-empirical and ab initio methods. The lowest conformations of 12-crown-3 and 12-crown-4 were found to have exodentate C 3 v and C 2 structure, respectively. In the case of the sandwich-type complexation, the nucleophilic cavity of 12-crown-3 rather than that of 12-crown-4 seemed to be optimal for complexation with the Na + ion. Four new bis(12-crown-3) derivatives ( 1 – 4 ) were examined as potential sodium ion-selective ionophores in poly(vinylchloride) (PVC) membrane electrodes. The ion-selective electrode (ISE) based on di(1,5,9-trioxacyclododecanylmethyl) 2-dodecyl-2-methylmalonate ( 1 ) had the highest selectivity for the sodium ion among the alkali and alkaline earths studied. The sodium ion selectivity of the ISE based on bis(12-crown-3) derivative 1 was superior to that of the ISE based on the bis(12-crown-4) analogue.

Synthesis and cation-extraction study of chromogenic 14-crown-4 derivatives for spectrophotometric determination of lithium

Three kinds of proton-dissociable chromogenic 14-crown-4 ethers have been synthesized, all of which possess a dinitrophenol chromophore. Proton-dissociation behavior of the chromogenic crown ethers in aqueous 1,4-dioxane (1/1), and extraction equilibria between the 1,2-dichloroethane solution containing the chromogenic crown ether and aqueous solutions of alkali-metal ions have been investigated spectrophotometrically. An excellent lithium-ion-selective chromogenic 14-crown-4 derivative was obtained by introducing a bulky decalino subunit and dinitrophenol chromophore, which has small pKa value, into the ethano-bridge section of the 14-crown-4 ring.

Ion-selective electrodes based on l-tryptophan and l-tyrosine

Novel ion-selective electrodes (ISEs) based on amino acids have been developed. L-Tryptophan and L-tyrosine, which are amino acids, are employed as ionophores for solvent polymeric membrane electrodes. The proposed ISEs show rapid Nernstian responses for the Cu(2+) ion over the concentration ranges of 3.0×10(-4)-1.0×10(-1) M. These ISEs exhibit comparatively good selectivity with respect to alkaline, alkaline earth, and some transition and heavy metal ions and the ammonium ion. The ISE based on tryptophan also indicates the Nernstian response for the benzylammonium ion.

METAL-ION STABILIZATION OF PHOTOINDUCED OPEN COLORED ISOMER IN CROWNED SPIROBENZOTHIAPYRAN

A spirobenzothiapyran derivative bearing a monoaza-12-crown-4 moiety affords significant thermal stability enhancement in the UV light induced colored merocyanine form of its photochromic moiety by metal-ion complexation of its crown ether moiety, although the complexation hardly induces the isomerization without photoirradiation.