Highly effective and reversible control of the rocking rates of rotaxanes by changes to the size of stimulus-responsive ring components

We have designed and synthesized rotaxanes whose rates of rocking motion (pendular motion) were switched reversibly through changes to the size of the ring component in response to external stimuli. The ring molecules of the rotaxanes incorporate a metaphenylene unit, which swings like a pendulum, and a dianthrylethane unit, which undergoes reversible isomerization in response to photo- and thermal stimuli and changes the size of the ring component. The rocking rates were estimated quantitatively by variable-temperature (VT) NMR spectroscopy and saturation transfer experiments, which revealed substantial changes in the rates between the open and closed forms, particularly in the case of rotaxanes with an isopropoxy group attached to a phenylene unit.     

Nanotransfer of the polythiophene molecular alignment onto the step-bunched vicinal Si(111) substrate

A poly(3-dodecylthiophene-2,5-diyl) film having in-plane anisotropic molecular arrangement was successfully fabricated by transferring its Langmuir-Blodgett film onto a step-bunched Si(111) substrate. Polarized near-edge X-ray absorption fine structure measurements revealed that the polythiophene main chains are preferentially orientated along periodic facet/terrace nanostructures on the step-bunched substrate, whereas less anisotropy was found on a flat substrate. The step-bunched Si substrate has been proved to be effective for controlling the in-plane molecular arrangement in the polymer thin film.     

Visible-light-induced oxidative removal of nitrogen oxides in air by metal chloride-modified titanium (IV) oxide nanoparticles

Various metal chloride-modified titanium(IV) oxide (TiO₂) (MCMT) samples were prepared by loading metal chloride on commercial TiO₂ nanoparticles (Ishihara ST-01) having a large specific surface area and used for photoinduced oxidative removal of nitrogen oxides (NO _x ) in air under irradiation of visible light and/or ultraviolet (UV) light. The NO _x removal activity of MCMT samples under photoirradiation from a blue fluorescent lamp (BFL) with a UV cut filter decreased in the following order: RhCl₃/ST-01>H₂PtCl₆/ST-01>RuCl₃/ST-01>ST-01>IrCl₄/ST-01>HAuCl₄/ST-01, indicating that RhCl₃. H₂PtCl₆ and RuCl₃ fixed on TiO₂ effectively worked as photosensitizers for NO _x removal. NO _x was almost quantitatively fixed as nitrate on RhCl₃/ST-01 photoirradiated with BFL or blue light-emitting diodes. Under irradiation of both visible light and UV light from a white fluorescent lamp, RhCl₃/ST-01 exhibited a higher level of removal of NO _x and a much lower level of release of nitrogen dioxide than did bare ST-01, indicating that RhCl₃/ST-01 effectively utilized both visible light and UV light and that two types of reaction (photosensitization by fixed RhCl₃ and photocatalysis by TiO₂) occurred over RhCl₃/ST-01.     

Electrochemical processes in a wire-in-a-capillary bulk-loaded, nano-electrospray emitter

Experiments are described that illustrate solvent oxidation, emitter electrode corrosion, and analyte oxidation in positive ion mode nano-electrospray mass spectrometry using a wire-in-a-capillary, bulk-loaded nano-electrospray emitter geometry. Time-lapsed color photography of pH and metal specific indicator solutions within operating nano-electrospray emitters, as well as temporal changes in the ions observed in the nano-electrospray mass spectra, are used to probe these reactions, judge their magnitude, and study the time dependent changes in solution composition and gas-phase ion signal brought about as a result of these electrochemical reactions. The significance of these observations for analytical applications of nano-electrospray mass spectrometry are discussed.     

Contrast Adaptation Effects under Interocular Suppression for Normal and Strabismic Observers

Our vision system receives two different images from our two eyes. Since these two images usually have high correlation they are fused into a single stable image. In binocular rivalry suppression a stimulus presented in one eye is suppressed and a different stimulus in the other eye is perceived for a certain time interval. For strabismic observers the suppression is continuous between different retinal images caused by misalignment of eye positions. Previous research investigated the effects of this binocular rivalry suppression on a number of visual processes. The present study looked at the effects of contrast adaptation for the adaptation stimulus presented to eyes under interocular suppression. We compared normal and strabismic observers and found that in both types, regardless of the existence of suppression, there was the effect of contrast adaptation. These findings provide evidence that the suppression occurs at a site in the visual system after the locus of contrast adaptation. The contrast adaptation strength differed in the two types of observers.     

Simple and Accurate Propagation-Angle Observation of a Collimated Laser Beam within a Short Optical Path Range by Use of a Dual-Focus Fresnel Lens

We propose a method for observing the propagation-angle displacement of a collimated beam with respect to the travel direction of a moving part by use of a dual-focus Fresnel lens. The fabricated binary-type dual focus Fresnel lens consisting of two portions having a different focal length from each other. 0.5 mrad angular accuracy within a travel range of 16mm was experimentally confirmed and then it was successfully applied to split-type optical head manufacturing.     

Stereodivergent Hydroboration of Allenes

Full details of a stereodivergent hydroboration of allenes are reported. While hydroboration of an allene with 9‐BBN provided a thermodynamically stable (E)‐allylic alcohol after oxidative work‐up, the reaction of an identical allene with HB(Sia)₂ (disiamylborane) formed a (Z)‐allylic alcohol as the kinetic product. The developed conditions allowed for the synthesis of trisubstituted olefins in a highly stereoselective fashion, which is known to be challenging. The method was also applied to the stereodivergent synthesis of structural motifs such as skipped dienes and allylbenzenes, which are often embedded in biologically active natural products.     

Simultaneous analysis of highly polar pharmaceutical adulterants in slimming products by hydrophilic interaction liquid chromatography

A chromatographic method utilizing hydrophilic interaction liquid chromatography was developed for the estimation of highly polar pharmaceutical adulterants in commercial slimming products. Five adulterants, phenylpropanolamine, salbutamol, phenformin, buformin, and metformin, were successfully separated on an XBridge^? amide column (3.5 µm, 4.6?×?250 mm) using a mobile phase composed of acetonitrile/26.5 mM ammonium formate containing 0.1% formic acid (85:15) flowing at the rate of 0.8?mL/min. Wavelengths for monitoring the elution of these compounds were determined based on the wavelength of their absorption maxima (λ_max?=?208, 226, and 236 nm). The developed method was validated for specificity, linearity, accuracy, precision, and robustness. Interassay comparison showed that the performance of the hydrophilic interaction liquid chromatography-based method was superior to that of the traditional reversed-phase liquid chromatography-based method. Therefore, the proposed method is useful to analyze highly polar pharmaceutical adulterants in slimming products.     

Photoinduced electron transfer of N-[(3- and 4-diarylamino)phenyl]-1,8-naphthalimide dyads: orbital-orthogonal approach in a short-linked D-A system

The photoinduced electron transfer of a series of meta- and para-linked triphenylamine-naphthalimide dyads, N-{3- and 4-[bis(4-R-substituted phenyl)amino]phenyl}-1,8-naphthalimide, 1m,p (R = H), 2m,p (R = Me), 3m,p (R = OMe), and 4m,p (R = NMe2) was investigated in toluene and DMF. The singlet charge-transfer (CT) states were observed in all cases. The decay rates were found to be faster in DMF (tau = 6.5 ps to 100 ps) than those in toluene (tau = 190 ps to 7 ns). The long-lived triplet CT states were observed in toluene for 3 (ca. 10% contribution, tau = 670 ns for 3m, 240 ns for 3p). No long-lived species were detected in DMF. The decay rates were somewhat faster in the para-isomers than in the meta-isomers in most cases. The photolysis of 5 (p-phenylene extended analogue of 3, R = OMe) gave a singlet CT state and a locally excited triplet state on the naphthalimide chromophore.