Even though two isosbestic points are generated in UV-induced changes in UV-vis absorption spectra of films of a polymethacrylate with azobenzene side chains, the corresponding fourth-order derivative spectra disclose the presence of H-aggregate so that the dual process comprised of UV-induced disaggregation and E/Z photoisomerization of non-aggregated species are involved.
The iridium-catalyzed direct C–H borylation of ring-fused (hetero)arenes afforded borylated products in a peri-selective manner, directed by a proximal hydrosilyl group. Further selective transformations of the boryl and silyl groups enabled the synthesis of various multisubstituted (hetero)arenes, such as 1,8-disubstituted naphthalenes and 3,4-diarylindole.
Adhesion between dissimilar materials is one important issue in materials technology. We demonstrate a feasible method for direct adhesion of dissimilar materials using host-guest interactions. Aluminum die casting substrate modified with β-cyclodextrin (βCD Al Sub) and carbon fiber reinforced plastic substrate (Ad CFRP Sub) or glass substrate modified with adamantane (Ad Glass Sub) are adhered by formation of inclusion complex between βCD and Ad units. The host-guest complex formation has achieved adhesions between dissimilar materials, βCD Al Sub/Ad CFRP Sub and βCD Al Sub/Ad Glass Sub. The jointing materials have shown re-adhesion properties through the host-guest interactions.
Poly(ethylene carbonate) (PEC)-based polymer electrolytes incorporated with magnesium bis(trifluoromethanesulfonyl) imide (Mg(TFSI)2) and triethylene glycol dimethylether (triglyme, G3) were investigated for their ion-conductive, thermal, structural and electrochemical properties. The highest conductivity was 5.2 × 10−6 S cm−1 at 80 °C for 40/60 of PEC/0.5 M Mg(TFSI)2-G3 (PEC/G3-0.5 M). The addition of G3 enhanced the conductivity and Mg deposition/dissolution process by enhancing the ionic mobility and the formation of appropriate solvation structure in PEC.
Toward enhancement of intercolumnar electronic communications in thermotropic columnar liquid-crystalline (LC) materials, we report LC crown ether-decorated phthalocyanine with the shortest intercolumnar distance among LC phthalocyanines. Moreover, the liquid crystallinity was variable by the introduction of square-planar metal ions, despite the subtle structural differences with a planar configuration.
In this work, efficient membrane-electrode assemblies (MEAs) have been successfully developed through in-situ chemical precipitation for application to water electrolysis for hydrogen-dissolved water production. The MEAs are fabricated by using cost-effective pore-filled proton exchange membranes possessing both low electrical resistances and proper crosslinking properties. The MEA prepared under the optimum conditions shows excellent water electrolysis performance mostly comparable with that of a commercial Nafion-based MEA.
A technique for immobilizing enzyme on Au electrode was developed. The oxygen reduction reaction activity of electrochemically deposited enzymes was higher than that of physically adsorbed enzymes. Based on the electrochemical quartz crystal microbalance measurements, the higher ORR activity of electrochemically deposited enzymes could be attributed to the proper orientation of the enzymes. In addition, the electrochemically deposited enzymes exhibited high stability with respect to potential cycles.
Cellulose nanocrystals (CNCs) were modified by surface grafting with silane and polyacrylate without disturbing the material morphologies. The modified CNCs exhibited improved hydrophobicity and thermal stability as a consequence of the grafted material on CNCs surface as well as the displacement of sulfate half-ester groups.
A short peptide having two naphthalene tags folds into a stable α-helix. The helix content of the peptide was 78%. The hydrophobic association of the naphthalene in the peptide was confirmed by its excimer fluorescence. When this hydrophobic association of the naphthalene was disturbed by forming inclusion complex with 2-hydroxypropyl-β-cyclodextrin (HPCD), the helix content was reduced to 64%. The binding of naphthalene on the peptide with HPCD was confirmed by its fluorescence spectra. On the other hand this inclusion complex on naphthalene and HPCD was inhibited with 1-adamantanol, the helix content of the peptide was completely recovered to 78%. The dual naphthalene tagged peptide displayed reversible folding of the α-helix.
Three tetrapodal tetraaryladamantanes bearing imidazole derivatives exhibit unique self-assembly and crystallization behaviors, including hollow spherical aggregation, a morphological change by fusion events, and phase transition into crystals. In crystals, the packing and arrangements of tetrapodal adamantanes are subject to the substituents of imidazole derivatives in the molecules.
The effects of the host crystal structure of an SrTa4O11:Er3+/Yb3+ up-conversion (UC) phosphor on its luminescence properties were investigated using the tetragonal tungsten bronze (TTB) and hexagonal polymorphs of the SrTa4O11 host. Hexagonal SrTa4O11:Er3+/Yb3+ showed bright luminescence, whereas the UC emission intensity of TTB SrTa4O11:Er3+/Yb3+ was very weak, corresponding to ≈1% that of the hexagonal phase. This result was attributed to the local crystal structure around the rare-earth ions in the host lattice.
Characteristics of direct urea fuel cells based on CuNi plated cloth as catalyst and current collector are reported. The power was significantly enhanced by coating the CuNi cloth with a conducting polymer, PEDOT*PSS. The cell exhibited the open circuit voltage of 0.68 V and the maximum power density of 1.88 mW cm−2 for 0.5 M urea at the room temperature.
Synthesis of 1-substituted 1-siloxy-3-aryloxybuta-1,3-dienes is achieved starting with readily available methyl ketones by a reaction sequence involving a palladium-catalyzed addition of the ketone to a 3,5-xylyl triisopropylsilylethynyl ether followed by isomerizations. This synthetic method is applicable to various methyl ketones. Cycloaddition of the resulting dienes with electron-deficient alkenes and alkynes gives 6-membered carbo- and heterocycles.
A novel hydrogel based on diglycolamide compound was prepared for the adsorption of rare earth ions. The hydrogel shows high adsorption capacity in 0.1 M HNO3, from the lowest 128 mg g−1 for La to the highest 214 mg g−1 for Yb. The presence of high concentrations of coexisting metal ions does not decrease the adsorption of rare earth ions.
Here, we report synthesis and properties of a di-ruthenium acetylide molecular wire having a diethynylporphyrinatomanganese linker, and the effect of the coordination of electron-donor molecules to the Mn center on the metal-metal interaction is also described. Electrochemical and spectroscopic studies of the wire reveal highly charge delocalized properties. Addition of pyridine in the presence of [NBu4][PF6] causes electrochemical and spectroscopic changes, suggesting modulation of the ruthenium-ruthenium interaction. On the basis of a DFT study, the formation of a cationic bis-pyridine adduct has been confirmed to play a key role in the modulaion.
Villin is a fast-folding protein and has a unique hydrophobic core at the center in its folded form. In the present study, the folding process of Villin was investigated with parallel cascade selection molecular dynamics (PaCS-MD). Our computational results show that formation of the central hydrophobic core was a rate-limiting step in the folding process. In more detail, the folding is regulated with a gathering of four PHE residues to form the hydrophobic core.
Novel host-guest binding motifs based on negatively charged carboxylatopillararene and carboxylatopillararene (CP5A and CP6A) with N,N′-bis(4-pyridylmethyl)-1,4-diaminobutane dihydrochloride (C4N4Cl2) were constructed. According to the integrated results of 1H NMR, 2D NOESY, and fluorescence titration experiments, we demonstrated that the molecular recognition between CP5A or CP6A with different cavity sizes and C4N4Cl2 in water not only has high stability constants but also has pH-responsiveness.
In this paper, magnetically recyclable Fe-doped lithium ion sieves (LFMO) with enhanced structure stability were synthesized using a solid state reaction method. The structure, adsorption capacity, dissolution loss and magnetic properties of as-prepared un-doped lithium ion sieve (LMO) and LFMO were characterized and compared. The results show that the as-prepared Fe-doped lithium ion sieves presented a dissolution loss of 0.26% and 0.10% (decrease about 90%) for Mn3+ and Fe3+, respectively, and adsorption capacity of 30.6 mg g−1 (decrease about 15%). Furthermore, LFMO could be easily recycled with a magnet, and the adsorption capacity of reused LFMO could be 20.7 mg g−1 after five adsorption-desorption cycles.
The transition of the near-infrared (NIR) region from singlet to triplet excited states (S–T transition) is effective to ensure wideband photosensitization. Here, we synthesize iminopyridine Ru(II) complexes, exhibiting S–T transitions in the NIR region. The dye-sensitized solar cell using the imino-pyridine Ru(II) complex exhibits photoelectric conversion by employing the aforementioned S–T transition.
Cis-cisoidal poly(substituted phenylacetylene)s have poor membrane forming ability. To solve this problem, we synthesized and polymerized three phenylacetylenes having a silicon-containing substituent and two hydroxyl groups. The resulting polymers had cis-cisoidal backbone, a high molecular weight, good solubility, and therefore good membrane forming ability. Their plots in a PO2/PN2 vs PO2 graph were very close to or over Robeson’s upper bound line. Especially poly(substituted phenylacetylene)s having oligosiloxanyl groups showed ultrahigh PO2 (>1,000 barrer).
Magnesium silicon nitride (MgSiN2) nanoparticles have been synthesized by using magnesium silicide (Mg2Si), sodium azide (NaN3) and sulfur as starting materials in a stainless steel autoclave at relatively low temperature. X-ray powder diffraction patterns indicate the obtained products are orthorhombic phase MgSiN2. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images reveal that the average size of product is 40 nm. The oxidation resistance of the obtained MgSiN2 nanoparticles has been investigated.
The catalytic formal hydration of alkynes and decarboxylation of alkynoic acid were developed using a Au catalyst featuring a Z-ligand. Furthermore, the intramolecular [4+2] cycloaddition of the alkynoic acid-alkene derivative for the formation of the oxabicyclo[4.4.0] skeleton also proceeded.
Regular conduction channels decorated with delicately designed functional group hold promise to accelerate hydroxide conduction. In this study, GO was modified with imidazolium-containing polymer brush, followed by vacuum filtration to prepare a laminar membrane. The interconnected parallel channels provide an unparalleled conduction pathway for hydroxide migration in which the in plane hydroxide conductivity reaches about 68.5 mS cm−1 for Im@GOM at 90 °C under 98% RH, outperforming that of polymer based membranes with similar IEC values.
SrSiO3−3xN2x with a single chain inosilicate structure, which has not been realized in Sr and Sr-rich metasilicates, has been synthesized by introduction of a small amount of nitrogen into SrSiO3. Its crystal structure was determined by a single-crystal X-ray analysis. Anion sites are severely distorted along b-axis, resulting in formation of the inosilicate structure. The present material activated with Eu2+ exhibits red emission under near ultraviolet and visible light irradiation. Our results suggest a new strategy for development of novel oxynitrides.
This study reports a method for the stereoselective copper(I)-catalyzed defluoroborylation of aliphatic gem-difluoroalkenes to afford (Z)-monofluoro-substituted borylalkenes. Gem-difluoroalkenes bearing a variety of functional groups were efficiently borylated with high stereoselectivity. A theoretical study of the reaction mechanism is also described.
Colloidal magnetite (Fe3O4) nanoparticles were synthesized via thermal decomposition of oleylamine-coordinated iron oxalate powder, which gradually becomes liquid at high temperature without the need of any chemical additions. Fe3O4 nanoparticles with an average diameter of 10.2 nm were synthesized in the liquid at 300 °C for 60 min. The synthesized Fe3O4 nanoparticles were well dispersed in toluene.
Electrochemiluminescence (ECL) of luminol is used to develop biosensors for detection of reactive oxygen species (ROS). Rapid and reagentless measurement of ROS is required for medical diagnosis and cellular assays. We immobilized N-(4-aminobutyl)-N-ethylisoluminol (ABEI) onto a screen-printed electrode (SPE) with a photo-crosslinking polymer. When 500 mV was applied to the working electrode, response to H2O2 was obtained within 1 s and an amount of 5 µM could be detected. Furthermore, we succeeded in evaluating the amount of ROS released from human neutrophils activated by phorbol myristate acetate.