Bioluminescent detection of insect pheromones using an enzyme-based flow injection analysis system

The combination of flow injection analysis with chemiluminescent detection is shown to provide extremely selective and sensitive detection of insect pheromones which possess an aldehyde moiety. The flow injection analysis system provides reproducible control of both the reaction chemistry and the sample introduction process. Microliter volume samples can be precisely handled and analyzed with this experimental configuration. The detection system is based on the luciferase-catalyzed oxidation of reduced flavin mononucleotide which occurs in the presence of aldehydes with carbon backbones of between 14 and 16 carbons. A limit of detection of 3 fmol of tetradecyl aldehyde is demonstrated and the system is shown to be insensitive to the presence of various organic solvents up to concentrations of approximately 10%. The key experimental variables which control sensitive detection of pheromone at the femtomole level with be investigated and discussed.     

A new entry to the isogeissoschizoid skeleton

[reaction: see text] The tetracyclic isogeissoschizoid skeleton has been prepared by a novel route that involves the ozonolysis and double reductive amination of a cyclopentene, a nickel-catalyzed cyclization, and a late-stage Fischer indole synthesis.     

A study of the reaction of bicyclo[5.1.0]octa-2,5-diene with sulphur dioxide

Thermally-induced reaction between bicyclo[5.1.0]octa-2,5-diene (I) and sulphur dioxide under dry conditions is toluene-d₈ as solvent leads to the unexpected formation of the hitherto unknown diene sulphone 7-thiabicyclo[4.2.1]nona-2,4-diene 7,7-dioxide (II).     

Self-assembling structures of long-chain phenyl glucoside influenced by the introduction of double bonds

Four long-chain phenyl glucoside amphiphiles possessing a saturated or unsaturated long alkyl chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembling properties were investigated by EF-TEM, SEM, CD, FT-IR, and XRD. Compound 2 possessing one double bond in the lipophilic portion showed twisted helical fibers, which formed a bilayered structure with a 3.59 nm period, while compound 3 showed the helical ribbons and left-handed nanotubular structures with 150-200 nm inner diameters and ca. 20 nm of wall. Very interestingly, compound 4 possessing three double bonds showed a nanotubular structure with ca. 70 nm of inner diameter through a helical ribbon, which formed a loose bilayered structure with 4.62 nm. These results indicate that self-assembling properties strongly depend on the number of cis double bonds.     

A CONVENIENT IRRADIATION CELL FOR FERRIOXALATE ACTINOMETRY

Abstract— A calibrated volumetric optical cuvette is described which both simplifies the technique and improves the precision of potassium ferrioxalate actinometry. The cuvette is used both for irradiation of the actinometer solution and for in situ dilution and chemical developing of the irradiated aliquot. The technique permits all but one manipulation to be carried out in total darkness, thus protecting the actinometer solutions from ambient light. The method can be extended to any actinometric procedure and the volumetric cuvettes are very useful in a variety of other spectrophotometric applications.     

Coulomb interaction in the one-dimensional free-electron model

In the limiting case of the free-electron theory where the electron motion is constricted to one dimension, the one-dimensional Coulomb potential gives rise to divergent interaction integrals. It is shown that a proposal by Olszewski to remove the divergenses by first evaluating the integrals in the three-dimensional case and then passing to the limit of one dimension only is incorrect, and that convergent integrals may only be obtained by suitably modifying the original one-dimensional Coulomb potential between particles.

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Zusammenfassung In dem Grenzfall des Modells der Freien Elektronen, in dem die Elektronenbewegung auf eine Dimension eingeschrÄnkt ist, ergibt das eindimensionale Coulombpotential divergente Wechselwirkungsintegrale. Es wird gezeigt, da\ ein Vorschlag von Olszewski zur Aufhebung der Divergenz durch übergang von dreidimensionalen zum eindimensionalen Integral falsch ist. Konvergente Integrale können nur durch geeignete VerÄnderung des ursprünglichen eindimensionalen Coulombpotentials erhalten werden.

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Résumé Dans le cas limite de la théorie de l'électron libre à une dimension, le potentiel coulombien donne lieu à des intégrales d'interaction divergentes. On montre que la proposition d'Oszewski pour éliminer les divergences, en évaluant d'abord les intégrales tridimensionnelles et en passant à la limite à une dimension, est incorrecte et que des intégrales convergentes ne peuvent Être obtenues qu'en modifiant le potentiel coulombien unidimensionnel entre particules.

     

Collision-induced dissociations of substituted benzyl anions: Deprotonated 2-Phenyl-1,3-dithiane

Deprotonated 2-phenyl-1,3-dithiane undergoes competitive losses of H˙, C₃H₆ C₂H₄S, C₃H₄S, C₇H₆S, C₁₀H₁₀ and C₁₀H₁₀S upon collisional activation. The elimination of H occurs from the phenyl ring. The loss of C₃H₆ occurs by simple cleavage of the dithiane ring. All other processes involve specific proton transfer followed by either cleavage or internal nucleophilic displacement.     

An efficient synthesis of cyercene A

An efficient approach to the total synthesis of the marine derived polypropionate cyercene A is described. A key feature of the synthesis is the development of methodology for the diastereoselective Wadsworth-Emmons type condensation of a functionalised γ-pyrone unit.