Highly regio- and stereoselective hydrometallation reactions of fluorine-containing internal alkynes: Novel approaches to fluoroalkylated alkenes

Hydroalumination, hydrocupration, and hydroboration reactions of various fluorine-containing alkynes were investigated. The alkyne reacted smoothly with 2.0 equiv. of Red-Al at −78 °C to give the hydroaluminated adduct in a highly regio- and stereoselective manner, which was treated with iodine, the corresponding vinyliodide being produced in moderate yield. Hydrocupration of the alkynes also took place, but the resulting vinylmetal reacted with various electrophiles sluggishly. In sharp contrast, the reaction with dicyclohexylborane proceeded smoothly to afford the cis-addition products preferentially, which were subjected to Suzuki-Miyaura cross-coupling reaction, leading to trisubstituted alkenes in high yields.     

Open-loop and closed-loop control of dissociative ionization of ethanol in intense laser fields

The relative yield of the C-O bond breaking with respect to the C-C bond breaking in ethanol cation C2H5OH+ is maximized in intense laser fields (10(13)-10(15) Wcm2) by open-loop and closed-loop optimization procedures. In the open-loop optimization, a train of intense laser pulses are synthesized so that the temporal separation between the first and last pulses becomes 800 fs, and the number and width of the pulses within a train are systematically varied. When the duration of 800 fs is filled with laser fields by increasing the number of pulses or by stretching all pulses in a triple pulse train, the relative yield of the C-O bond breaking becomes significantly large. In the closed-loop optimization using a self-learning algorithm, the four dispersion coefficients or the phases of 128 frequency components of an intense laser pulse are adopted as optimized parameters. From these optimization experiments it is revealed that the yield ratio of the C-O bond breaking is maximized as far as the total duration of the intense laser field reaches as long as approximately 1 ps and that the intermittent disappearance of the laser field within a pulse does not affect the relative yields of the bond breaking pathways.     

Reagentless biosensor for isocitrate using one step modified Pt-Ir microelectrode

The Pt-Ir microelectrode modified through one step electropolymerization is proposed for the isocitrate amperometric biosensor construction. The enzyme (isocitrate dehydrogenase-ICDH), coenzyme (NADP(+)) and mediator (Meldola's Blue) were immobilized onto the microelectrode surface in one step from a PIPES buffer solution containing pyrrole. The optimized experimental conditions were 25 cycles of cyclic voltammetric in a solution containing 3.58 10(-5) mol l(-1) of mediator, 3.51 10(-4) mol l(-1) of coenzyme and 2.68 U ml(-1) of enzyme. In contrast to the biosensor for isocitrate reported in literature, just one enzyme was immobilized and no coenzyme addition in the solution of analysis was necessary. Catalytic currents were proportional to the isocitrate concentration between 7.7 10(-6) and 1.04 10(-4) mol l(-1), showing good repeatability. The detection limit of the proposed biosensor was 3.50 10(-6) mol l(-1), the response time was lower than 20 s, the lifetime was about 30 determinations and no significant interference of sugars and citric acid was verified. Orange juice samples were analysed by both methodology biosensor and spectrophotometric commercial kit, and the obtained results presented a good correlation. The data demonstrated that the developed biosensor is suitable for isocitrate determination in orange juice without matrix interferences.     

Pressure response of Raman spectra of water and its implication to the change in hydrogen bond interaction

In situ Raman spectroscopic measurements of water in the region of OH vibration were conducted up to 0.4 GPa at 23 and 52 degrees C. The frequencies of the decomposed OH stretching bands initially decreased with increasing pressure, reached a minimum at 0.15 GPa and increased up to 0.3 GPa and then decreased, which corresponds to the variations of the strength of hydrogen bonding. This variation was observed at 23 degrees C, but not at 52 degrees C, which suggests a change in pressure dependence on the hydrogen bond interaction between these two temperatures. Based on the equilibration model between hydrogen-bonded and nonhydrogen-bonded molecules, the present experimental results indicate that the pressure variation of the viscosity depends on the ratio of hydrogen-bonded molecules, rather than the strength of hydrogen bonding between molecules.     

Micro‐ and Nano‐Technologies for Lipid Bilayer‐Based Ion‐Channel Functional Assays

Ion channel proteins provide gated pores that allow ions to passively flow across cell membranes. Owing to their crucial roles in regulating transmembrane ion flow, ion channel proteins have attracted the attention of pharmaceutical investigators as drug targets for use in the studies of both therapeutics and side effects. In this review, we discuss the current technologies that are used in the formation of ion channel‐integrated bilayer lipid membranes (BLMs) in microfabricated devices as a potential platform for next‐generation drug screening systems. Advances in BLM fabrication methodology have allowed the preparation of BLMs in sophisticated formats, such as microfluidic, automated, and/or array systems, which can be combined with channel current recordings. A much more critical step is the integration of the target channels into BLMs. Current technologies for the functional reconstitution of ion channel proteins are presented and discussed. Finally, the remaining issues of the BLM‐based methods for recording ion channel activities and their potential applications as drug screening systems are discussed.     

NMR and MO Studies on the Molecular Structure of a Fluoranthene-Benzene Complex

Summary. Fluoranthene (FA) forms a 1:1 van der Waals complex with benzene in cyclohexane. The ¹H NMR spectrum of this complex shows that the FA moiety in the complex state has five kinds of hydrogen atoms and that the ¹H NMR peaks assigned to the protons attached to the naphthalene skeleton are largely shifted to higher magnetic field on complex formation with benzene. These observations indicate that the complex takes the structure of C_S symmetry, in which the benzene molecule mainly interacts with the electronic system localized on the naphthalene moiety of FA. The present ab initio calculations reproduce well the ¹H NMR spectral shifts mentioned above and the experimentally predicted C_S structure of the complex. According to the PPP calculations for the electronic absorption spectral changes on the complex formation, the FA-benzene complex is considered to take a sandwich type structure.     

Catalytic activity and regeneration property of a Pd nanoparticle encapsulated in a hollow porous carbon sphere for aerobic alcohol oxidation

A core-shell composite consisting of a palladium (Pd) nanoparticle and a hollow carbon shell (Pd@hmC) was employed as a catalyst for aerobic oxidation of various alcohols. The core-shell structure was synthesized by consecutive coatings of Pd nanoparticles with siliceous and carbon layers followed by removal of the intermediate siliceous layer. Structural characterizations using TEM and N(2) adsorption-desorption measurements revealed that Pd@hmC thus-obtained was composed of a Pd nanoparticle core of 3-6 nm in diameter and a hollow carbon shell with well-developed mesopore (ca. 2.5 nm in diameter) and micropore (ca. 0.4-0.8 nm in diameter) systems. When compared to some Pd-supported carbons, Pd@hmC showed a high level of catalytic activity for oxidation of benzyl alcohol into benzaldehyde using atmospheric pressure of O(2) as an oxidant. The Pd@hmC composite also exhibited a high level of catalytic activity for aerobic oxidations of other primary benzylic and allylic alcohols into corresponding aldehydes. The presence of a well-developed pore system in the lateral carbon shell enabled efficient diffusion of both substrates and products to reach the central Pd nanoparticles, leading to such high catalytic activities. This core-shell structure also provided high thermal stability of Pd nanoparticles toward coalescence and/or aggregation due to the physical isolation of each Pd nanoparticle from neighboring particles by the carbon shell: this specific property of Pd@hmC resulted in possible regeneration of catalytic activity for these aerobic oxidations by a high-temperature heat treatment of the sample recovered after catalytic reactions.     

Immunosensor for Detection of the Textile Dye Disperse Orange 1 Based on Non‐conventional Competitive Assay

Textile dyes appear as an important class of compounds that has become a matter of public concern and a serious challenge for scientists and environmentalists due to their large‐scale production and extensive application. In this work, a non‐conventional competitive‐type amperometric immunosensor was successfully developed for detection of the textile dye Disperse Orange 1 (DO1). The DO1 was magnetically captured and separated from the sample solution using magnetic particles (MP) functionalized with the antibody anti‐DO1 and with HRP and gold electrodes were modified with the conjugate DO1‐BSA. Molecules of DO1 immobilized on the electrode surface and DO1 captured by MP compete for antibody binding sites. As a result, the amperometric signal decreases with increasing target DO1 concentration at the capture step, because this decreases, the attachment between the HRP coated MP and the electrode. This strategy allowed us to determine DO1 at the low detection limit of 0.87 ng mL^?1 with great specificity. Also, there were good recoveries for detection of the textile dye in river water samples without the need of sample pre‐treatment. The competitive amperometric immunosensor shows applicability for the determination of small molecules that cannot be determined by conventional competitive or sandwich immunosensors.     

Fluorescence studies on phenylene moieties embedded in a framework of periodic mesoporous organosilica

The excited state characteristics of phenylene (Ph)-bridged periodic mesoporous organosilica (PMO) powders with crystal-like and amorphous wall structures are investigated. Crystal-like Ph-PMO has a molecular ordering of the bridging organic moieties with intervals of 0.76 and 0.44 nm parallel and perpendicular to the mesochannel direction, respectively, whereas amorphous Ph-PMO has no molecular-level periodicity in the wall. Fluorescence from the exciton and excimer of the Ph moieties and the defect center in the silicate network were detected at room temperature, but fluorescence from the excimer and the defect center were not detected at 77 K for crystal-like Ph-PMO dispersed in a methanol/ethanol mixed solvent. The decay curve of the exciton fluorescence of crystal-like Ph-PMO at room temperature was analyzed successfully using a one-dimensional diffusion model quenched by the defect center and the excimer site. The results were discussed in comparison with those for the crystal-like biphenylene-bridged PMO reported in the preceding paper (Yamanaka et al., Phys. Chem. Chem. Phys., 2010, 12, 11688-11696). The existence of excited states with various conformations including ground state dimers or aggregates of the Ph moieties was suggested for amorphous Ph-PMO. It was clearly apparent that the differences in the excited state dynamics reflected the differences in the molecular-level structure in the wall.     

Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles

Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double‐decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [Tb^III(tpp)₂]ⁿ (tpp: tetraphenylporphyrinato, n=?1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [Tb^III(oep)₂]^?1 and [Tb^III(oep)₂]⁰ (oep: octaethylporphyrinato), but φ=36° for [Tb^III(oep)₂]⁺¹. Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system.