Development of a chemical vapor sensor using piezoelectric quartz crystals with coated unusual lipids

Piezoelectric quartz crystal sensors were developed using lipids with various properties for highly sensitive detection of chemical vapors. Lipids with varying lengths of alkyl chains were coated onto 10 MHz AT-cut quartz crystal resonators and the response of these modified crystals to chemical vapors were measured. It was shown that hydrophilic compounds, such as ethanol and methanol, could be recognized efficiently by lipids having shorter alkyl chains, whereas lipids with longer alkyl chains showed affinity to more hydrophobic vapors, such as toluene, hexane and cyclohexane. Frequency changes caused by adsorption of alcohols could be enhanced when cholesterol was co-immobilized in the lipid layer. To confirm the assumption that the sensor-response might be affected by the properties of lipids derived from acyl chains, we have examined the effects of two types of newly synthesized unusual lipids on sensor response. When lipids having one triple bond each at different positions on their alkyl chains were coated onto quartz crystals separately, lower responses were observed compared to responses obtained for a sensor with immobilized, saturated phosphatidylcholine. Lipids containing -branched acyl chains, however, showed good affinity for organic vapors, and sensor responses improved 4–5-fold. Moreover, these sensors were shown to have sensitivity of the same order as the humans' sense of smell (10⁻⁵–10⁻⁶ w/w in liquid paraffin) when measured using standard odorants (isovaleric acid, skatole, etc.) for an olfactometry established in Japan.     

Syndiotactic 1,2-polybutadiene with Co-CS2 catalyst system. IV. Mechanism of syndiotactic polymerization of butadiene with cobalt compounds–organoaluminum–CS2

A mechanism is proposed for the polymerization of syndiotactic 1,2-polybutadiene (s-PB) with soluble cobalt-organoaluminum-CS₂. The proposed active species have structures which consist of side-on coordination of CS₂ to cobalt, anti-π-allyl growing end, cisoid bidentate coordination of butadiene, and activation by complex formation with organoaluminum at the nonbonded sulfur of the coordinated CS₂. This proposal is based on findings for the aluminum-free catalyst Co(C₄H₆)(C₈H₁₃)-CS₂. It is tentatively interpreted that syndiotactic 1,2 polymerization proceeds under the influence of the side-on coordinated CS₂, by which the reactivity between the terminal carbons of butadiene and the C3 of the π-allyl end is enhanced.     

Homoleptic cyclometalated iridium complexes with highly efficient red phosphorescence and application to organic light-emitting diode

Phosphorescence studies of a series of facial homoleptic cyclometalated iridium(III) complexes have been carried out. The complexes studied have the general structure Ir(III)(C-N)(3), where (C-N) is a monoanionic cyclometalating ligand: 2-(5-methylthiophen-2-yl)pyridinato, 2-(thiophen-2-yl)-5-trifluoromethylpyridinato, 2,5-di(thiophen-2-yl)pyridinato, 2,5-di(5-methylthiophen-2-yl)pyridinato, 2-(benzo[b]thiophen-2-yl)pyridinato, 2-(9,9-dimethyl-9H-fluoren-2-yl)pyridinato, 1-phenylisoquinolinato, 1-(thiophen-2-yl)isoquinolinato, or 1-(9,9-dimethyl-9H-fluoren-2-yl)isoquinolinato. Luminescence properties of all the complexes at 298 K in toluene are as follows: quantum yields of phosphorescence Phi(p) = 0.08-0.29, emission peaks lambda(max) = 558-652 nm, and emission lifetimes tau = 0.74-4.7 micros. Bathochromic shifts of the Ir(thpy)(3) family [the complexes with 2-(thiophen-2-yl)pyridine derivatives] are observed by introducing appropriate substituents, e.g., methyl, trifluoromethyl, or thiophen-2-yl. However, Phi(p) of the red emissive complexes (lambda(max) > 600 nm) becomes small, caused by a significant decrease of the radiative rate constant, k(r). In contrast, the complexes with the 1-arylisoquinoline ligands are found to have marked red shifts of lambda(max) and very high Phi(p) (0.19-0.26). These complexes are found to possess dominantly (3)MLCT (metal-to-ligand charge transfer) excited states and have k(r) values approximately 1 order of magnitude larger than those of the Ir(thpy)(3) family. An organic light-emitting diode (OLED) device that uses Ir(1-phenylisoquinolinato)(3) as a phosphorescent dopant produces very high efficiency (external quantum efficiency eta(ex) = 10.3% and power efficiency 8.0 lm/W at 100 cd/m(2)) and pure-red emission with 1931 CIE (Commission Internationale de L'Eclairage) chromaticity coordinates (x = 0.68, y = 0.32).     

Novel and efficient method for esterification, amidation between carboxylic acids and equimolar amounts of alcohols, and amines utilizing Me2NSO2Cl and N,N-dimethylamines; its application to the synthesis of coumaperine, a natural chemopreventive dieneamide

Various carboxylic esters or amides were prepared in good to excellent yield between carboxylic acids and equimolar amounts of alcohols or amines under very mild conditions (0-45°C; within 3 h) using dimethylsulfamoyl chloride (Me₂NSO₂Cl; 1) combined with N,N-dimethylamines (Me₂NR: 2a; R=Me, 2b; R=Bu). The choice of the sulfamoyl chloride and the amine is crucial for the reaction; that is, sterically uncrowded amines accelerated the present esterification and amidation. This agent had some advantages over methanesulfonyl chloride (3)/amines as for the atom-economy, avoidance of side reactions, and had very high chemoselectivity toward the carboxyl group vs the hydroxyl group; the experiment was performed by the addition of 1 to the mixture of carboxylic acids and alcohols. Application of this method to the synthesis of coumaperine, a chemopreventive natural product, was performed using the present amidation as a key step.     

Neutron activation analysis of low level lithium in water samples

For determining low level lithium concentrations in water, a neutron activation method based on the measurement of tritium radioactivity produced by⁶Li(n,)³H reaction has been developed. This method is specific and free from interference by other chemical elements. Using a low background liquid scintillation counter for tritium measurement, the detection limit is approximately 0.3 ppm during irradiation at a thermal neutron flux density of 1.1·10⁷n·cm^–2·s^–1 for 6 hours by a small nuclear reactor and liquid scintillation counting for 2000 minutes     

Synthesis and absolute configuration of +-lineatin,the pheromone of trypodendronlineatum

A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.0^4,7] nonane, $\text{1}$) was achieved. The stereochemistry of (+)-lineatin was established as 1$\text{R}$, 4$\text{S}$, 5$\text{R}$, 7$\text{R}$ by an X-ray crystallographic analysis of an intermediate $\text{1}$$\text{5}$.     

Reaction of poly(vinyl chloride) with magnesium and grignard reagents

Reaction of poly(vinyl chloride) with magnesium under various conditions was attempted, but poly(vinyl chloride) did not react with magnesium. The reactions of poly(vinyl chloride) with benzylmagnesium chloride and allylmagnesium chloride as Grignard reagents were carried out in tetrahydrofuran at reflux temperature. It was found that the chlorine atoms in the poly(vinyl chloride) were replaced by benzyl and allyl groups by the coupling reaction, and a small amount of Grignard reagent of poly(vinyl chloride) was formed by the magnesium–halogen exchange reaction. The extent of the substitution increased with increasing reaction time and concentration of the Grignard reagent.     

ε-optimality criteria for convex programming problems via exact penalty functions

In this paper, we present-optimality criteria for convex programming problems associated with exact penalty functions. Several authors have given various criteria under the assumption that such convex problems and the associated dual problems can be solved. We assume the solvability of neither the convex problem nor the dual problem. To derive our criteria, we estimate the size of the penalty parameter in terms of an-solution for the dual problem.