Application of Odorless Thiols for the Cleavage of 2‐ and 4‐Nitrobenzenesulfonamides

Several odorless or faint‐smelling thiols were tested to cleave 2‐ and 4‐nitrobenzenesulfonyl groups, which are widely utilized for selective protection and activation of amines. p‐Mercaptobenzoic acid (7) was found to be the most useful thiol for cleaving the o‐ and p‐nosyl groups in terms of ease of separation of the product from the workup residue, reaction temperature, and reaction time.     

Reverse phenomena of magnetic field effects and time-resolved EPR spectra in the photogenerated biradical from intramolecular electron-transfer in a phenothiazine–C60 linked compound with a semi-rigid spacer

Photoinduced electron-transfer reactions and magnetic field effects (MFEs) on the decay rates of the photogenerated biradical in a phenothiazine (Ph)–C₆₀ linked compound with a biphenyl group (Ph(BP)C₆₀) were examined in benzonitrile and benzene. Fluorescence and transient absorption spectra indicate that the intramolecular electron-transfer for Ph(BP)C₆₀ from the Ph to the singlet or triplet excited state of C₆₀ was suppressed by the biphenyl group. The decay rates of the photogenerated biradical decreased in the 0–0.2 T magnetic field range and increased in the 0.2–1 T magnetic field range. The reverse phenomena of the MFEs in Ph(BP)C₆₀ were strongly enhanced with increasing temperature and similar to those in Ph(n)C₆₀ (n = 6?12). The MFEs in Ph(BP)C₆₀ can be governed by spin-lattice relaxation and/or spin-spin relaxation mechanisms as observed in Ph(n)C₆₀ (n = 6?12). Time-resolved EPR spectra of Ph(BP)C₆₀ showed absorption, emission, absorption and emission patterns, and are quite different from those in Ph(n)C₆₀ (n = 4?12). The result indicates that the magnitude and distribution of the exchange interaction |2J| in Ph(BP)C₆₀ are smaller than those in Ph(n)C₆₀ (n = 4?12) and charge recombination occurs in the inverted region because the sign of the J is positive.     

Optimization of silica support pore size for Pt catalysts in the complete oxidation of volatile organic compounds

Highest catalytic performance for complete oxidation of propylene and toluene was obtained by using a Pt catalyst on a mesoporous silica support with pore sizes from 20 to 50 nm and 10 to 40 nm, respectively.     

Synthesis and lectin-binding activity of luminescent silica particles peripherally functionalized with lactose

A novel O-protected lactose (Galβ1→4Glcβ1-) derivative bearing trimethoxysilyl group at the aglycon was developed as a silane coupling agent. Reaction of the coupling agent with tris(2,2′-bipyridine)ruthenium (II) dichloride (Rubpy) doped silica particle gave a Rubpy-doped silica particle peripherally functionalized with O-protected lactose derivative. De-O-protection of the particle with aqueous ammonia provided lactose-coating Rubpy-doped silica particles, combining luminophor encapsulated in silica matrix and carbohydrate having lectin-recognition ability. Specific adhesion of fluorescein isothiocyanate-labeled peanut agglutinin (FITC-PNA) to the lactose-coating Rubpy-doped silica particles was confirmed by fluorescence microscopic analysis.     

On Boolean primitive positive clones

Kuznecov introduced the concept of primitive positive clones and proved in 1977 that there are 25 Boolean primitive positive clones in a notoriously unavailable article. This paper presents a new proof of his result, relating it to Post's lattice and exhibiting finite bases for those clones.     

Radical polymerization of styrene derivatives bearing N‐free amino acid side chains,synergic effect of chirality,and hydrogen bonding for stereoselective polymerization

Radical polymerization of styrene derivatives having a series of amino acid, alanine, glycine, leucine, valine, Boc‐leucine, and Boc‐valine, in the side chain bound at the C‐terminal was conducted to regulate the stereoinduction system in the propagation step. Isotacticity increased in the polymer main chain, especially in the polymerization of monomers bearing N‐free L ‐leucyl and L ‐valyl esters in THF or DMF at 50 °C, by the synergic stereoregulation with chirality control and hydrogen bonding between the radical polymer terminal and the monomer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Taste masking of propiverine hydrochloride by conversion to its free base

The aim of the present study was to mask the bitterness of propiverine hydrochloride (P-4) by converting it to propiverine free base. Fine granules comprising the free base, which was converted from P-4 by desalination, were prepared. By using Fourier transform infrared spectroscopy, thermogravimetry-differential thermal analysis, and powder X-ray diffraction spectra, we confirmed that P-4 had been converted into propiverine free base by desalination during the manufacturing process. Furthermore, the conversion into free base appeared to result in decreased solubility, and both the taste testing sensor and tasting volunteers determined that it masked the bitterness of P-4. On using the gustatory sensation test, the bitterness of the P-4 fine granules was confirmed to be weakened. The dissolution rate and bioavailability of fine granules of the free base were compared with tablets of P-4. The dissolution rate and bioavailability of the fine granules and tablets were almost the same. We successfully masked the taste of P-4 by converting it into free base using a manufacturing process that was suitable for commercial manufacturing.     

Compressed exponential relaxation in liquid silicon: universal feature of the crossover from ballistic to diffusive behavior in single-particle dynamics

We report a first-principles molecular-dynamics study of the relaxation dynamics in liquid silicon (l-Si) over a wide temperature range (1000-2200 K). We find that the intermediate scattering function for l-Si exhibits a compressed exponential decay above 1200 K including the supercooled regime, which is in stark contrast to that for normal "dense" liquids which typically show stretched exponential decay in the supercooled regime. The coexistence of particles having ballistic-like motion and those having diffusive-like motion is demonstrated, which accounts for the compressed exponential decay in l-Si. An attempt to elucidate the crossover from the ballistic to the diffusive regime in the "time-dependent" diffusion coefficient is made and the temperature-independent universal feature of the crossover is disclosed.     

Synthesis and functional evaluation of chiral dendrimer-triamine-coordinated Gd complexes as highly sensitive MRI contrast agents

Novel chiral dendrimer-triamine-coordinated Gd complexes were synthesized and shown to have longitudinal relaxivity (r1) 3 times higher than that of clinically used Gd-DTPA. The pharmacokinetic differences between optical isomers were estimated from the affinity of 2-(R) and 2-(S) with bovine serum albumin (BSA), respectively, by a quartz crystal microbalance (QCM) measurement. As a result, the association constant K_a of 2-(S) was about 4 times higher than that of 2-(R), which means that 2-(S) is retained in the vascular retention for a longer time after administration. This result was also supported by T1-weighted MR images of mice before and after the intravenous injection of 2-(R) and 2-(S), as well as the time-course of the signal intensities (SI) at the blood vessels and quantification of Gd³⁺ concentration in the blood and urine.