Nanosize effect on high-rate Li-ion intercalation in LiCoO2 electrode

Recently, battery technology has come to require a higher rate capability. The main difficulty in high-rate charge-discharge experiments is kinetic problems due to the slow diffusion of Li-ions in electrodes. Nanosizing is a popular way to achieve a higher surface area and shorter Li-ion diffusion length for fast diffusion. However, while various nanoelectrodes that provide excellent high-rate capability have been synthesized, a size-controlled synthesis and a systematic study of nanocrystalline LiCoO2 have not been carried out because of the difficulty in controlling the size. We have established the size-controlled synthesis of nanocrystalline LiCoO2 through a hydrothermal reaction and, for the first time, clarified the structural and electrochemical properties of this intercalation cathode material. Lattice expansion in nanocrystalline LiCoO2 was found from powder X-ray diffraction measurements and Raman spectroscopy. Electrochemical measurements and theoretical analyses on nanocrystalline LiCoO2 revealed that extreme size reduction below 15 nm was not favorable for most applications. An excellent high-rate capability (65% of the 1 C rate capability at 100 C) was observed in nanocrystalline LiCoO2 with an appropriate particle size of 17 nm.     

Non-enzymatic covalent protein labeling using a reactive tag

We describe herein a new method for covalent labeling of proteins using a complementary recognition pair of peptide tag and synthetic molecular probe. The rapid and specific covalent labeling of a tag-fused protein was achieved by the reaction on the tag site with the probe through their selective molecular recognition. The advantages of this method involve the facile functional modification and the high labeling specificity of the tag-fused protein, which are demonstrated in the labeling experiments in various conditions even inside cells.     

Gold-catalyzed cyclization of (ortho-alkynylphenylthio)silanes: intramolecular capture of the vinyl-Au intermediate by the silicon electrophile

The gold-catalyzed cyclization of (ortho-alkynylphenylthio)silanes 1 produced the corresponding 3-silylbenzo[b]thiophenes 2 in good to excellent yields. For example, the reaction of [2-(1-pentynyl)phenylthio]triisopropylsilane 1a, [2-(p-anisylethynyl)phenylthio]triisopropylsilane 1e, and [2-(phenylethynyl)phenylthio]triisopropylsilane 1g in the presence of 2 mol % of AuCl in toluene at 45 degrees C gave 2a, 2e, and 2g in 98, 99, and 97% yields, respectively. This reaction proceeds through intramolecular capture of the vinyl-Au intermediate by the silicon electrophile, so-called silyldemetalation.     

Highly Regioselective Palladium‐Catalyzed Carboxylation of Allylic Alcohols with CO2

Various allylic alcohols were carboxylated in the presence of a catalytic amount of PdCl₂ and PPh₃ using ZnEt₂ as a stoichiometric transmetalation agent under a CO₂ atmosphere (1 atm). This carboxylation proceeded in a highly regioselective manner to afford branched carboxylic acids predominantly. The β,γ‐unsaturated carboxylic acid thus obtained was successfully converted into an optically active γ‐butyrolactone, a known intermediate of (R)‐baclofen.     

Neutron investigations of the magnetic properties of Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>S under pressure up to 4.2 GPa

Fe _x Mn_1?x S belongs to the group of strong electron correlations compounds MnO. We present here experimental results for the antiferromagnetic iron–manganese sulfide system, based on X-ray and neutron diffraction studies. The neutron diffraction investigations were carried out at ambient conditions and at hydrostatic pressures up to 4.2 GPa in the temperature range from 65 to 300 K. Our results indicate that the Néel temperature of α-MnS increases up to room temperature by applying chemical (x _Fe) or weak hydrostatic pressure P. In Fe_0.27Mn_0.73S, the Néel temperature increases from 205(2) K (P = 0 GPa) to 280(2) K (P = 4.2 GPa) and the magnetization at 100 K decreases by a factor of 2.5 when the hydrostatic pressure increases from 0 to 4.2 GPa.     

Microphase‐separated structure of 1,3‐cyclohexadiene/butadiene triblock copolymers and its effect on mechanical and thermal properties

We report the effect of microphase‐separated structure on the mechanical and thermal properties of several poly(1,3‐cyclohexadiene‐block‐butadiene‐block‐1,3‐cyclohexadiene) triblock copolymers (PCHD‐block‐PBd‐block‐PCHD) and of their hydrogenated derivatives: poly(cyclohexene‐block‐ethylene/butylene‐block‐cyclohexene) triblock copolymers (PCHE‐block‐PEB‐block‐PCHE). Both mechanical strength and heat‐resistant temperature (ex. Vicat Softening Temperature: VSPT) tended to increase with an increase in the 1,3‐cyclohexadiene (CHD)/butadiene ratio. On the other hand, heat resistance of the hydrogenated block copolymer was found to be higher than that of the unhydrogenated block copolymer. However, the mechanical strength was lower than those of the unhydrogenated block copolymer with the same ratio of CHD to butadiene. To clarify the relationship between the higher order structures of those block copolymers and their properties, we observed the microphase‐separated structure by transmission electron microscope (TEM). Hydrogenated block copolymers were found to have more finely dispersed microphase‐separated structures than those of the unhydrogenated block copolymers with the same CHD/Bd ratios through the use of TEM and the small‐angle X‐ray scattering (SAXS) technique. Those results indicated that the segregation strength between the PCHE block sequence and the PEB block sequence increased, depending on hydrogenation of the unhydrogenated precursor. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 13–22, 2001     

Synthesis of novel hydrocarbon polymers containing 6‐membered rings in the main chain: living anionic polymerization of 1,3‐cyclohexadiene

The n‐butyllithium (n‐BuLi)/N,N,N',N'‐tetrametylethylene‐diamine (TMEDA) system (the molar ratio of TMEDA to n‐BuLi higher than 4/4) has been found to polymerize 1,3‐cyclohexadiene (1,3‐CHD) to produce “living” polymer having narrow molecular weight distribution with well‐controlled polymer chain length. Binary and ternary block copolymers with narrow molecular weight distribution could be synthesized from 1,3‐cyclohexadiene, styrene, and butadiene with very high efficiency. These polymers and their hydrogenated derivatives have excellent thermal, mechanical, chemical, and optical properties for the new industrial materials.