Upon polarized laser beam irradiation, achiral azobenzene-based molecular glass particles changed their forms to wavy string-like structures in agar gel, and their ends were found to have helical structures with a left-handed rather than right-handed screw. Such chiral photomechanical behavior was suggested to be due to different dynamic viscoelasticity between clockwise and counterclockwise rotations of the surrounding agar gel, confirmed by the behavior of the gel sliding down in a glass tube.
Catalyst-free conversion of 2,5-bis(hydroxymethyl)furan (BHMF) in water gave valuable cyclopentenones (4-hydroxy-4-hydroxymethyl-2-cyclopentenone and 4-hydroxy-3-hydroxymethyl-2-cyclopentenone). BHMF was obtained by reduction of 5-hydroxymethylfurfural (5-HMF), which can be easily obtained from common biomass resources. The ratio of the cyclopentenones in the converted mixture can be controllable by adjusting reaction temperature and time. This method would be an environmentally friendly approach because of conversion of 5-HNF to cyclopentenones via BHMF synthesis does not require any additive and proceeds under mild conditions.
Plasmonic photoluminescence of Cu nanoparticles was observed in colloidal dispersion by using nanosheets as a support, where acridine orange was adsorbed as an energy donor. The energy transfer took place efficiently followed by the plasmonic photoluminescence, which was enhanced other Cu nanoparticles located nearby on the nanosheet.
A 3D metallic Li anode (Li/Ag@CC) is obtained by injecting molten Li into Ag2S-modified carbon cloth (Ag2S@CC). The experimental observations reveal that the lithiothermic reaction of loaded Ag2S with molten Li and the capillary effect of carbon cloth matrix improve the Li wettability of Ag2S@CC. Benefiting from the miscibility of nano-Ag and Li on the carbon fibers, the Li/Ag@CC can effectively induce the uniform stripping/plating behavior of Li to inhibit dendrite growth, resulting in a long lifetime over 2000 h with low voltage hysteresis and fluctuation. Furthermore, the S||Li/Ag@CC full battery exhibits a high reversible capacity of 5.4 mAh cm−2 and stable cycling performance for 200 cycles.
The intercalation of spiro-(1,1′)-bipyrrolidinium (SBP) cation into a graphite electrode from propylene carbonate (PC) is performed in graphite/activated carbon capacitors. The effect of the electrolyte salt concentration on the storage behavior of PC-solvated SBP+ cation in graphite electrode is investigated by electrochemical tests, in situ X-ray diffraction and electrochemical quartz crystal microbalance measurements.
Catalytic performance of copper phosphates (Cu-POx) with different Cu/P molar ratios for the partial oxidation of methane with O2 has been investigated. Cu-POx catalysts showed extremely superior performance for the formation of formaldehyde by methane oxidation to other metal phosphates containing Mn, Fe, Ni or Co. Cu-POx catalysts with α-Cu2P2O7 phase showed the highest yield of formaldehyde among all Cu-POx catalysts with different copper phosphate phases in methane oxidation at 923 K.
Zn2+-exchanged ZSM-5 (Zn/ZSM-5) zeolite is an effective catalyst for ethane dehydroaromatization (EDA) reaction. However, Zn/ZSM-5 shows a short catalyst lifetime on EDA reaction. In this study, Cr species was loaded on the Zn/ZSM-5 by an incipient wetness impregnation method. The Cr-loaded Zn/ZSM-5 showed an improved catalyst lifetime. The Cr species induced a different reaction path to coke formation and moderated excess acidity of Zn/ZSM-5, which probably contributed to the improved catalyst lifetime. This work provides a new strategy to improve the catalytic stability of zeolites on EDA reaction.
This paper describes the inclusion complexation behaviors of anti-viral favipiravir (1) into native and permethylated cyclodextrins (CDs) in aqueous media. The formations of inclusion complexes are supported by UV-vis spectra, Job plots, and mass spectral measurements. The association constants between 1 and CDs are systematically estimated by titration experiments.
We herein report that an onium salt-forming reaction of triarylphosphines with aryl bromides is promoted by the sequential cooperation of light with palladium. The mild reaction conditions tolerate various functionalities such as amino and hydroxy groups, and thus, the present method offers a convenient and expedient access to variously substituted tetraarylphosphonium salts.
Transmetallation of zinc μ-methylene species to various metal chlorides has been attempted to generate early transition metal methylene species. A dinuclear chromium μ-methylene complex has been isolated and characterized by X-ray crystallography. Carbene/alkyne metathesis of the chromium methylene complex with 1,6-enyne was demonstrated.
Assemblies of cationic gold nanorods (AuNRs) via electrostatic interactions with double-stranded (ds) DNA were investigated in solution and after evaporation as a cast-film. Interestingly, moderately positively charged AuNRs assembled with dsDNA provided a monolayer sheet with an ordered alignment resembling a two-dimensional (2D) smectic structure during solvent evaporation.
The synthesis of 8-aryl-2H-cyclohepta[b]furan-2-ones was accomplished by the Suzuki-Miyaura coupling of arylboronic acids with the triflates prepared from an 8-hydroxy-2H-cyclohepta[b]furan-2-one derivative. The 8-aryl-2H-cyclohepta[b]furan-2-ones were converted to 4-arylazulenes via an [8 + 2] cycloaddition reaction with the enamine prepared from acetaldehyde and diethylamine. The optical properties of 4-arylazulenes were characterized by UV/Vis and fluorescence spectra.
The constrained thorough search (CTS) method has been applied to extended X-ray absorption fine structure (EXAFS) analysis of PtRu bimetallic nanoparticles for fuel-cell anode catalysts that are highly resistant to CO poisoning. The PtRu has a cluster-in-cluster or homobondphilic structure. CTS analysis of EXAFS data not only analyzes Pt and Ru edge-EXAFS data simultaneously but also includes the physical constraints with errors. The method is expected to make EXAFS analysis more reliable than the conventional curve-fitting method.
A seawater magnetohydrodynamic (MHD) power generator is a unique system that not only transforms the kinetic energy of ocean and tidal currents directly into electric energy but also generates hydrogen gas by seawater electrolysis. In this study, we constructed experimental equipment and an electrochemical flow cell, which simulated a linear-type seawater MHD power generator, and investigated the effect of magnetic field on seawater electrolysis. Under magnetic field under solution flow conditions, we clarified that the strength of the magnetic field affected the current value of seawater electrolysis, which indicates that the MHD power generation was successfully simulated by the developed experimental equipment and electrochemical flow cell. Our electrochemical measurement results suggested that magnetic field was correctly applied to the cell and that the Lorentz force acted on the ions in the electrolyte solution, showing improvement in hydrogen evolution reaction (HER) efficiency under the MHD power generation conditions.
The reaction of N-pyrimidinyl aniline derivatives with internal alkynes in the presence of a catalytic amount of a Ni(0) complex results in the alkyne annulation of C-F/N-H, with the formation of indole derivatives. C-F bond activation, a key step in this reaction, is promoted by a pyrimidine directing group. The use of a base, such as NaH is required for the reaction to reach completion.
Chloroform (CHCl3) upon bubbling with O2 containing ∼2% Cl2 underwent oxidative photochemical conversion to phosgene (COCl2) when exposed to a white LED light. Cl2 may serve as a visible light-responsive radical initiator in the radical chain reactions of CHCl3 and O2. This photochemical reaction allowed both in situ and stepwise one-pot phosgenation reactions, which are simple and safe methods, without expensive apparatus. It can be applied to a variety of conventional organic syntheses using phosgene and phosgene oligomers.
When a Li film deposited on a Ni(111) single-crystal was immersed in three kinds of electrolyte solutions, a uniform Li2O ultra-thin film was formed only in the O2-saturated tetraglyme solution containing 1 M LiNO3 and 50 mM LiBr. It was clarified by an in situ grazing incidence surface X-ray diffraction measurement. We found that this Li2O ultra-thin film stably exists during an electrochemically dissolution/deposition reaction, i.e., discharging/charging cycles at the anode of the Li-O2 battery, and effectively suppresses dendrite formation.
Since iron (Fe) is an important trace nutrient for marine organisms, establishing a tracer of the Fe cycle through the food chain is crucial. Herein, we report the variation in δ56Fe in marine organisms (n = 32, nine species) collected around the Northwest Pacific Ocean. The δ56Fe value varied from −2.64‰ to −0.03‰, which is consistently lower than the reported seawater value. This variation was predominantly controlled in terms of species rather than size and region, suggesting that this proxy is useful to assessing species-specific Fe metabolic processes.
In this study, a hygroelectric cell, which generates electricity based on variations in humidity using a deliquescent electrolyte solution partitioned by a cation-exchange membrane, was modeled. In addition, simulations were performed to predict the power generated by the cell. The results of the simulations, which considered the evaporation and condensation rates of water and the water permeability of the ion-exchange membrane, which depend on the water activity, were in keeping with those obtained experimentally.
The oxygen reduction reaction (ORR) on a strained Pt (100) surface has been studied using periodic density functional theory (DFT) calculations. The results showed a linear relationship between strain and the d-band center. The adsorption energy displayed greater sensitivity to compressive strain and the adsorption energy results indicated that the bridge site was more stable after the adsorption of *OH, *O and *OOH. Concomitantly, the calculated free energy diagram results confirmed that compression deformation could reduce the over potential of the ORR reaction and increase the catalyst activity on the Pt (100) surface. The evolution of H2O exhibited the largest free energy difference, suggesting that it was a potentially rate limiting step. Notably, the limiting potentials for the individual steps were fitted by the *OOH vs. *OH or *O scaling relationship and the maximum overpotential value for the ORR reaction was 0.820 V when the compressive strain reached −10%. This study provided mechanistic and quantitative guidance for the rational selection of stress regulation strategies to fabricate Pt catalysts with desirable electrocatalytic activity in emerging energy applications.
Photoreactivity of three-coordinate triarylboranes bearing a neighboring Lewis base moiety was investigated. o-Anisyldimesitylborane underwent skeletal rearrangement under photoirradiation conditions to give (2-benzyl-4,6-dimethylphenyl)mesitylborinic acid after hydrolysis. Experimental studies and theoretical calculations supported that the reaction proceeded via a triplet excited state to form a spiro boracycle intermediate through C–H abstraction and radical coupling. This study disclosed unique difference in photoreactivity of triarylboranes depending on the neighboring Lewis base moiety.
We have developed a sample tube for solid-state NMR that enables the application of high-intensity radiofrequency (rf) fields. Herein, an rf-shielding device is inserted into the tube, and the sample is loaded between them. The flux of the rf-field is compressed into the sample space, resulting in a high-intensity rf-field at the sample. A prototype was used to investigate the rf-field strength at the sample, which can be increased to twice that of the compared device.
In this paper, AgBiS2 was prepared on a TiO2 nanorod array via sequential spin-coating 5 mM AgNO3 in DMF, 5 mM Bi(NO3)3 in DMF and 10 mM Na2S in methanol/water (v/v, 95/5) by successive ionic layer absorption and reaction (SILAR) at room temperature. The effect of SILAR cycle times, C11H23COOH surface modification, and spiro-OMeTAD:P3HT application on the photovoltaic performance of the AgBiS2 sensitized solar cell was systematically investigated. The optimal SILAR cycle time for preparing the AgBiS2 sensitized TiO2 nanorod array was 20. The AgBiS2 sensitized solar cell exhibited a power conversion efficiency (PCE) of 0.56% with a 20 cycle time, 0.70% with C11H23COOH surface modification and 0.91% with spiro-OMeTAD:P3HT.
Dendralene and its analogs possessing both strongly electron-donating 1,3-dithiol-2-ylidenes and electron-accepting dicyanomethylidenes (2b–4b) were successfully synthesized. X-ray structure analysis revealed that 2b adopts a nonplanar structure, in which half units of 2b are significantly inclined to each other. Cyclic voltammograms of 2b–4b consisted of one pair of two-electron oxidation waves and one pair of one-electron reduction waves.