Isotope exchange between iron(II or III) hydroxide and HTO water in the equilibrium state

Observing the OT-for-OH exchange reaction between iron(II or III) hydroxide and tritiated water (HTO) leads to the following results: (1) isotope exchange as atomic group occurred between the OH group in each iron hydroxide (i.e., Fe(OH)₂ or Fe(OH)₃) and OT^– resulted from the dissociation of HTO; (2) the ratio of the reactivity of the hydroxides is roughly [iron(III) hydroxide]: [iron(II) hydroxide]=1.21.0 and the result is related to a difference in electronegativity between Fe²⁺ and Fe³⁺. (In other words, if the reactivity depends on the number of the charge, the ratio should be 1.51.0).     

Iron-catalyzed enyne cross-coupling reaction

In the presence of 0.5-1 mol % of FeCl(3) with lithium bromide as a crucial additive, alkynyl Grignard reagents, prepared from the corresponding alkynes and methylmagnesium bromide, react with alkenyl bromides or triflates to give the corresponding conjugated enynes in high to excellent yields. The reaction shows wide applicability to various terminal alkynes and alkenyl electrophiles.     

Solvent control of optical resolution of 2-amino-1-phenylethanol using dehydroabietic acid

The optical resolution of 2-amino-1-phenylethanol (2-APE) by the solvent switch method was investigated using dehydroabietic acid (DAA), a natural chiral acid obtained as one of the main components of disproportionated rosin. The solvent dependency of optical rotation measurements of 2-APE, DAA and the diastereomeric salts suggested solvent control of optical resolution. Both (R)- and (S)-2-APE were resolved, as the first success for aminoalcohols, only by changing the resolving solvents: (S)-2-APE was obtained in high optical purity by a single crystallization operation with polar solvents (epsilon > 50), whereas the efficiency was lower for (R)-2-APE using less polar solvents (20 < epsilon < 40). The results were compared and discussed with reference to the crystal structures of the diastereomeric salts.     

Nitrogen Plasma Enhanced Low Temperature Atomic Layer Deposition of Magnesium Phosphorus Oxynitride (MgPON) Solid-State Electrolytes

Solid-state batteries (SSBs) that use solid electrolytes instead of flammable liquid electrolytes have the potential to generate higher specific capacity and offer better safety. Magnesium (Mg) based SSBs with Mg metal anodes are considered to be one of the most promising energy storage candidates, because it gives high theoretical volumetric capacities of 3830 mAh cm⁻³. Here, we demonstrate an atomic layer deposition (ALD) process with a double nitrogen plasma process that successfully produces nitrogen-incorporated magnesium phosphorus oxynitride (MgPON) solid-state electrolyte (SSE) thin films at a low deposition temperature of 125 °C. The ALD MgPON SSEs exhibit an ionic conductivity of 0.36 and 1.2 μS cm⁻¹ at 450 and 500 °C, respectively. The proposed ALD strategy shows the ability of conformal deposition nitrogen-doped SSEs on pattered substrates and is attractive for using nitride ion-conducing films as protective or wetting interlayers in solid-state Mg and Li batteries.     

pH-Dependent catalytic activity and chemoselectivity in transfer hydrogenation catalyzed by iridium complex with 4,4'-dihydroxy-2,2'-bipyridine

Transfer hydrogenation catalyzed by an iridium catalyst with 4,4'-dihydroxy-2,2'-bipyridine (DHBP) in an aqueous formate solution exhibits highly pH-dependent catalytic activity and chemoselectivity. The substantial change in the activity is due to the electronic effect based on the acid-base equilibrium of the phenolic hydroxyl group of DHBP. Under basic conditions, high turnover frequency values of the DHBP complex, which can be more than 1000 times the value of the unsubstituted analogue, are obtained (up to 81 000 h(-1) at 80 degrees C). In addition, the DHBP catalyst exhibits pH-dependent chemoselectivity for alpha,beta-unsaturated carbonyl compounds. Selective reduction of the C=C bond of enone with high activity are observed under basic conditions. The ketone moieties can be reduced with satisfactory activity under acidic conditions. In particular, pH-selective chemoselectivity of the C=O versus C=C bond reduction was observed in the transfer hydrogenation of cinnamaldehyde.     

Aminoglycoside Antibiotics: New Insights into the Biosynthetic Machinery of Old Drugs

2‐Deoxystreptamine (2DOS) is the unique chemically stable aminocyclitol scaffold of clinically important aminoglycoside antibiotics such as neomycin, kanamycin, and gentamicin, which are produced by Actinomycetes. The 2DOS core can be decorated with various deoxyaminosugars to make structurally diverse pseudo‐oligosaccharides. After the discovery of biosynthetic gene clusters for 2DOS‐containing aminoglycoside antibiotics, the function of each biosynthetic enzyme has been extensively elucidated. The common biosynthetic intermediates 2DOS, paromamine and ribostamycin are constructed by conserved enzymes encoded in the gene clusters. The biosynthetic intermediates are then converted to characteristic architectures by unique enzymes encoded in each biosynthetic gene cluster. In this Personal Account, we summarize both common biosynthetic pathways and the pathways used for structural diversification.

     

Light-harvesting energy transfer and subsequent electron transfer of cationic porphyrin complexes on clay surfaces

A novel energy-transfer system involving nonaggregated cationic porphyrins adsorbed on an anionic-type clay surface and the electron-transfer reaction that occurs after light harvesting are described. In the clay-porphyrin complexes, photochemical energy transfer from excited singlet zinc porphyrins to free-base porphyrins proceeds. The photochemical electron-transfer reaction from an electron donor in solution (hydroquinone) to the adsorbed porphyrin in the excited singlet state was also examined. Because the electron-transfer rate from the hydroquinone to the excited singlet free-base porphyrin is larger than that to the excited singlet zinc porphyrin, we conclude that the energy transfer accelerates the overall electron-transfer reaction.     

Nepalensinols D-G, new resveratrol oligomers from Kobresia nepalensis (Cyperaceae) as potent inhibitors of DNA topoisomerase II

Four new resveratrol oligomers, nepalensinols D-G, were isolated from the stem of Kobresia nepalensis (Cyperaceae). The structures were determined by detailed NMR spectral analysis. The compounds were assessed for their inhibitory activity against human topoisomerase II, a potential target of anti-tumor agents. These stilbenoids showed potent inhibitory activity against human topoisomerase II with IC50 values of 5-15 microM.     

Generalized characteristic interface conditions for high-order multi-block computation

In practical fluid computation with structured grids around complex geometries, singular points with metric discontinuity can frequently be found. Generally, the grid singularities may cause numerical oscillations when some high-order finite difference scheme is applied. Recently, an excellent theory has been proposed which solves the above singular problem by block decomposition along the singular surface and by imposition of the characteristic interface conditions (CIC) on the block interface. However, the original theory has constraints on the mathematical treatment of the block interface, and therefore prevents numerical flexibility from a practical point of view. In this article, in order to extend the functions of the original CIC, we propose the generalized characteristic interface conditions (GCIC). Proper numerical test analysis is conducted to validate the performance of the GCIC, and as a practical application, multi-block computation is performed with the GCIC applied to complex geometry.     

Systematic Measurement of pd Breakup Cross Section Around Space Star

Space Star (SS) anomaly in nd breakup cross section was first reported in 1989 at E _n = 13 MeV (Strate et al. in Nucl Phys A 501:51, 1989), but its origin has not been found yet. In order to obtain suggestions for its origin, we made systematic measurements of pd breakup cross section around SS. In SS configuration, three outgoing nucleons form an equilateral triangle and the triangle is perpendicular to the beam axis. Necessity of the equilateral and perpendicular conditions of SS anomaly was investigated by systematic experiments. Also energy dependence of SS anomaly is being studied at energies from E _p = 7.5 to 13 MeV.