A Chemically and Electrochemically Switchable [2]Catenane Incorporating a Tetrathiafulvalene Unit

A mechanical switch in a [2]catenane , made up of a cyclobis(paraquat-p-phenylene) tetracation interlocked with a macrocyclic polyether containing a redox-active tetrathiafulvalene (TTF) unit and a 1,5-dioxynaphthalene ring system, can be thrown either chemically or electrochemically. The neutral TTF unit resides “inside” the tetracationic cyclophane in the reduced state and “alongside” it in the oxidized species (TTF⁺/ TTF²⁺). Switching between the reduced (I⁴⁺) and oxidized state (I⁵⁺(I⁶⁺)) is accompanied by a dramatic color change.     

Rational approximations of the Arrhenius integral using Jacobi fractions and gaussian quadrature

The aim of this work is to find approaches for the Arrhenius integral by using the n-th convergent of the Jacobi fractions. The n-th convergent is a rational function whose numerator and denominator are polynomials which can be easily computed from three-term recurrence relations. It is noticed that such approaches are equivalent to the one established by the Gauss quadrature formula and it can be seen that the coefficients in the quadrature formula can be given as a function of the coefficients in the recurrence relations. An analysis of the relative error percentages in the approximations is also presented.     

Calorimetric and SEM studies of PHB–PET polymeric blends

PHB [poly (3-hydroxybutyrate)], post-consumer soft-drink bottles poly (ethylene terephthalate) PET (herein named PET-R) and PHBPET-R (blends of PHB and PET-R in several compositions) samples were evaluated by differential scanning calorimetry (DSC) and scanning electronic microscopy (SEM) in order to verify their thermal properties and porosity according to amounts of PET-R added the blends. The DSC curve showed that the solvents used to solve the polymer mixture cause changes in the thermal behavior of PET-R films and in PHBPET-R blends. SEM studies of the PHBPET-R blends show that with a gradual mass increase of PET-R, there are gradual increases in the porosity of the films.     

Continuous separation of particles using a microfluidic device equipped with flow rate control valves

We propose herein an improved microfluidic system for continuous and precise particle separation. We have previously proposed a method for particle separation called "pinched flow fractionation." Using the previously reported method, particles can be continuously separated according to differences in their diameters, simply by introducing liquid flows with and without particles into a specific microchannel structure. In this study, we incorporated PDMS membrane microvalves for flow rate control into the microfluidic device to improve the separation accuracy. By adjusting the flow rates distributed to each outlet, target particles could be precisely collected from the desired outlet. We succeeded in separating micron and submicron-size polymer particles. This method can be used widely for continuous and precise separation of various kinds of particles, and can function as an important part of microfluidic systems.     

Ring expansion of functionalized octahydroindoles to enantiopure cis-decahydroquinolines

A new synthetic entry to enantiopure cis-decahydroquinolines is reported. Endo and exo derivatives of cis-1-benzyl-2-(hydroxymethyl)octahydroindol-6-one ethylene acetal undergo ring enlargement upon treatment with TFAA and then Et3N (thermodynamic conditions) to give enantiopure 1-benzyl-3-hydroxydecahydroquinolin-7-one derivatives in 77 and 82% yield, respectively. For 2-(1-hydroxyethyl) analogues, the best synthetic result is obtained from the (2S,1'R) endo isomer, which under kinetic reaction conditions (MsCl, THF, -20 degrees C, then AgOAc at rt ) gives the expanded product in 54% yield.     

Enantioselective total synthesis of (S)-bisoranjidiol, an axially chiral bisanthraquinone

The first enantioselective total synthesis of the bisanthraquinone (S)-bisoranjidiol and an unnatural regioisomer has been accomplished. Key features of the synthesis include the asymmetric oxidative biaryl coupling of a hindered 8-substituted 2-naphthol, selective para-quinone formation, and regioselective tandem Diels-Alder/aromatization reactions.     

Selective dehydrogenative silylation-hydrogenation reaction of divinyldisiloxane with hydrosilane catalyzed by an iron complex

A hydride and a silyl group of hydrosilane is introduced into 1,3-divinyldisiloxane in the presence of a catalytic amount of (η(5)-C(5)H(5))Fe(CO)(2)Me. Instead of the product expected from the well-known hydrosilylation reaction, the product obtained is that characteristic of dehydrogenative silylation at one vinyl group and hydrogenation at the other vinyl group of 1,3-divinyldisiloxane. Based on deuterium labeling experiments, a catalytic cycle for this new reaction has been proposed.     

Synthesis of enantiopure cis-decahydroquinolines from homotyramines by Birch reduction and aminocyclization

Birch reduction of homotyramines with a syn-β-amino alcohol unit followed by acid treatment of formed dihydroanisole derivatives gives polysubstituted enantiopure cis-decahydroquinolines. The stereoselectivity of the process differs if the hydroxyl group is free or protected. The procedure allows the synthesis of 7-oxodecahydroquinolines embodying four stereogenic centres with the same relative configuration as that of lepadins F and G.     

Coeffective and de Rham cohomologies of symplectic manifolds

We discuss the relation of the coeffective cohomology of a symplectic manifold with the topology of the manifold. A bound for the coeffective numbers is obtained. The lower bound is got for compact Kähler manifolds, and the upper one for non-compact exact symplectic manifolds. A Nomizu's type theorem for the coeffective cohomology is proved. Finally, the behaviour of the coeffective cohomology under deformations is studied.