Synthesis and photophysical properties of two dual oligothiophene-fullerene linkage molecules as photoinduced long-distance charge separation systems

To further extend photoinduced charge separation previously observed for oligothiophene-fullerene dyads (nT-C60), we have studied two novel dual oligothiophene-fullerene triads, 8T-4T-C60 and 4T-8T-C60, where quaterthiophene (4T) and octithiophene (8T) are linked by a trimethylene chain and either one is attached to a fullerene (C60). The cyclic voltammograms and electronic absorption spectra of these triad compounds indicated no electronic interactions among the three components. On the other hand, the emission spectra were markedly perturbed by electron transfer and/or energy transfer from the oligothiophene to fullerene. Detailed comparisons between the emission spectra of the triads (8T-4T-C60 and 4T-8T-C60) and the dyads (4T-C60 and 8T-C60) suggest that the additionally attached octithiophene or quaterthiophene in the triads is involved in the photophysical decay mechanism, and the 8T-4T-C60 triad undergoes photoinduced electron transfer leading to long-distance charge separation. This was actually corroborated by observation of the specific bands due to 8T*+-4T-C60*- species in the transient absorption spectra after photoexcitation of the octithiophene. The sandwich device based on the 8T-4T-C60 triad produced a more effective photovoltaic response to visible light owing to the contribution of the additional octithiophene chromophore compared to that using the dyad 4T-C60. On the other hand, the 4T-8T-C60-based device demonstrated a rather poorer photovoltaic performance when compared to the 8T-C60 device.     

Efficient syntheses of naturally occurring 3,4-dihydroxyprolines: Electrophile-mediated lactonization of 2-amino-3-hydroxy-4-pentenoic acid derivatives

Stereospecific conversion of β-hydroxyallylglycine derivatives into (2$\text{S}$, 3$\text{R}$, 4$\text{R}$) 1 and (2$\text{S}$, 3$\text{S}$, 4$\text{S}$) 2 $\text{via}$ halo- or mercuri-lactonization has been described.     

Synthesis of the serine equivalent, (2R) and (2S)-amino-3-butenol derivatives. Synthetic approaches to the metal chelating poly-amino acid, “aspergillomarasmine A”

Chiral synthons, equivalent to the C₃ amino acid serine, were synthesized in both (2$\text{R}$) and (2$\text{S}$) form from $\text{D}$ or $\text{L}$-methionine respectively; Utilization of this synthon in the construction of metal chelating poly-amino acid aspergillomarasminea A skeleton is presented.     

3D particle measurements by single beam two-views magnified digital in-line holography

Holography technique can be used for 3D measurement of particle positions. However, in general in-line holography, accurate determination of the object’s position in the optical axis direction is difficult. In order to overcome this defect, we proposed a two-views recording technique combined with a digital in-line holography. The two-views recording is executed by only one camera with the assistance of one mirror, capturing the real image of a particle and the mirror image of the same particle simultaneously. This method keeps simplicity of optical alignment and is free from a difficult calibration of multiple cameras. It was confirmed that the proposed technique can reduce the uncertainty in the depth direction to about 1 pixel. For application of this method to micro-PIV, magnified recording is desired. In this paper, magnified holograms were also taken through a lens. It was confirmed that the uncertainty in the optical-axis direction can be reduced to a few pixels by the proposed technique for the magnified holograms.     

Magnetic Textures and Dynamics in Magnetic Weyl Semimetals

Recent theoretical and experimental attempts have been successful in finding magnetic Weyl semimetal phases, which show nodal-point structure in the electronic bands as well as magnetic orders. Beyond uniform ferromagnetic or antiferromagnetic orders, nonuniform magnetic textures, such as domain walls and skyrmions, enrich the properties of the Weyl electrons even more in such materials. Here, a topical review on interplay between Weyl electrons and magnetic textures in those magnetic Weyl semimetals is given. The basics of magnetic textures in nontopological magnetic metals are reviewed first, and then the effect of magnetic textures in Weyl semimetals is discussed, regarding the recent theoretical and experimental progress therein. The idea of the fictitious “axial gauge fields” is pointed out, which effectively describes the effect of magnetic textures on the Weyl electrons and can well account for the properties of the electrons localized around magnetic domain walls.     

A Phosphate-Based Silver–Bipyridine 1D Coordination Polymer with Crystallized Phosphoric Acid as Superprotonic Conductor

Phosphate-based silver–bipyridine (Ag-bpy) 1D coordination polymer {[{Ag(4,4′-bpy)}₂{Ag(4,4′-bpy)(H₂PO₄)}] ⋅ 2 H₂PO₄ ⋅ H₃PO₄ ⋅ 5 H₂O}_n ( 1 ) with free phosphoric acid (H₃PO₄), its conjugate base (H₂PO₄⁻) and water molecules in its lattice was synthesized by room-temperature crystallization and the hydrothermal method. An XRD study showed that coordinated H₂PO₄⁻, lattice H₂PO₄⁻ anions, free H₃PO₄ and lattice water molecules are interconnected by H-bonding interactions, forming an infinitely extended 2D H-bonded network that facilitates proton transfer. This material exhibits a high proton conductivity of 3.3×10⁻³ S cm⁻¹ at 80 °C and 95 % relative humidity (RH). Furthermore, synthesis of this material from commercially available starting materials in water can be easily scaled up, and it is highly stable under extreme conditions of conductivity measurements. This report inaugurates the usage and design principle of proton-conducting frameworks based on crystallized phosphoric acid and phosphate.     

High-Resolution Electrochemical Mapping of the Hydrogen Evolution Reaction on Transition-Metal Dichalcogenide Nanosheets

High-resolution scanning electrochemical cell microscopy (SECCM) is used to image and quantitatively analyze the hydrogen evolution reaction (HER) catalytically active sites of 1H-MoS₂ nanosheets, MoS₂, and WS₂ heteronanosheets. Using a 20 nm radius nanopipette and hopping mode scanning, the resolution of SECCM was beyond the optical microscopy limit and visualized a small triangular MoS₂ nanosheet with a side length of ca. 130 nm. The electrochemical cell provides local cyclic voltammograms with a nanoscale spatial resolution for visualizing HER active sites as electrochemical images. The HER activity difference of edge, terrace, and heterojunction of MoS₂ and WS₂ were revealed. The SECCM imaging directly visualized the relationship of HER activity and number of MoS₂ nanosheet layers and unveiled the heterogeneous aging state of MoS₂ nanosheets. SECCM can be used for improving local HER activities by producing sulfur vacancies using electrochemical reaction at the selected region.