Optimization of Fe/SiO<Subscript>2</Subscript> based metal oxides as selective oxidation catalyst of propane with combinatorial approach

A combinatorial optimization with genetic algorism was performed on the five generations of 0.05 atm% Fe/SiO₂ added multi-metal oxides to be used as catalytic materials for the selective oxidation of propane to give aldehydes at 623-773 K. The loaded multi-metal oxides consist of some elements selected from seven elements with various atomic charges or redox properties. For the best materials, selectivity toward aldehydes from 35% at 1st generation to 45% at 4th generation were achieved at 5% propane conversion. Further rational optimization of the best performance catalyst also improves the selectivity up to 49.5%.     

Synthesis of fullerene glycoconjugates through sulfide connection in aqueous media

[reaction: see text] A thiolate/alkyl halide coupling reaction in aqueous media provides a one-step synthesis of fullerene glycoconjugates bearing five carbohydrate groups in good yield by using stoichiometric amounts of reactants, without recourse to hydroxy group protection. The sulfide-connection methodology is also useful for synthesis of simpler amphiphilic fullerene molecules, such as one bearing five carboxylic acid groups.     

β-Methallylrhodium(III) supported on a vanadium oxide cluster: Synthesis,structure, and reaction

Reaction of [(³-C₄H₇)₂Rh(CH₃CN)₂]PF₆(³-C₄H₇ = -methallyl) with [n-Bu₄N](VO₃) gives a new ³-allyl cluster [n-Bu₄N]₂[{(³-C₄H₇)₂Rh}₂ (V₄O₁₂)] (I) which is readily converted into a diene cluster, [n-Bu₄N]₂ [{(⁴-C₈H₁₄)Rh}₂(V₄O₁₂)] (II) (C₈H₁₄=2,5-dimethyl-1,5-hexadiene) by reacting with CO or P(OEt)₃;I andII have been characterized crystallographically.     

Akaike's Information Criterion for Stoichiometry Inference of Supramolecular Complexes

“How do we decide the stoichiometry of host–guest complexes?” This question has long been answered by the Job plot since its first report in 1928. However, as the Job plot was claimed to be misleading in 2016, the question became an open question again and called for renewed investigations. An information-theoretic approach, called Akaike's information criterion, is introduced in this study to select the best model of host–guest complexes, which can rank the models with weight of evidence. A few test cases with unique cylindrical hosts were examined to demonstrate the applicability of the information-theoretic method. Consequently, reasonable views over the thermodynamic behaviors of dumbbell-and-cylinder complexes were obtained. Akaike's information criterion can be a useful and superior alternative to statistical null hypothesis testing, which was proposed as a remedy in place of the Job plot.     

Controlling the incorporation and release of C60 in nanometer-scale hollow spaces inside single-wall carbon nanohorns

We succeeded in large-scale preparation of single-wall carbon nanohorns (SWNH) encapsulating C60 molecules in a liquid phase at room temperature using a "nano-precipitation" method, that is, complete evaporation of the toluene from a C60-SWNH-toluene mixture. The C60 molecules were found to occupy 6-36% of the hollow space inside the SWNH, depending on the initial quantity of C60. We showed that the C60 in C60@SWNHox was quickly released in toluene, and the release rate decreased by adding ethanol to toluene. Numerical analysis of the release profiles indicated that there were fast and slow release processes. We consider that the incorporation quantity and the release rate of C60 were controllable in/from SWNHs because SWNHs have large diameters, 2-5 nm.     

Capillary column high-performance liquid chromatographic-electrospray ionization triple-stage quadrupole mass spectrometric analysis of proteins separated by two-dimensional polyacrylamide gel electrophoresis application to cerebellar protein mapping

A method is presented for the structural characterization of proteins separated by two-dimensional poly-acrylamide gel electrophoresis (2D-PAGE). The method includes separation of a protein mixture by 2D-PAGE, recovery of proteins from the gel spots revealed by copper staining and analysis of the proteins by triple-stage quadrupole mass spectrometry using an electrospray ionization interface (ESI-TSQMS). Prior to the mass spectrometric analysis, the extracted proteins were passed through a small reversed-phase column (10 × 4.0 mm I.D.) to remove salts and gel-derived contaminants and then introduced into the mass spectrometer through a reversed-phase capillary column with 0.25 mm I.D. Application of the method to the analysis of rat cerebellar proteins suggests that the molecular mass could be accurately determined with sub-picomole amounts of protein samples derived from one or two 2D gels. The method was also useful for peptide mapping and determination of amino acid sequences of proteins micro-prepared from the 2D gel. Because 2D-PAGE has an excellent resolving power in protein separation and because capillary LC-ESI-TSQMS provides structural information with very small amounts of samples, the combined system of 2D-PAGE and capillary LC-ESI-TSQMS described here should allow wide applications to molecular studies of genes and proteins, such as identifications of protein spots on 2D gels, confirmation of gene/protein sequences and analysis of post-translational modification of proteins present naturally in tissue/cell extracts or expressed by recombinant DNA techniques.     

Stereocontrolled Synthesis of (−)-5,11-Dideoxytetrodotoxin

New derivatives of an intriguing marine natural product are now accessible. The first asymmetric synthesis of the simple tetrodotoxin analogue, 5,11-dideoxytetrodotoxin ( 3 ), was achieved. Hydroxylation at position C8 of the key intermediate 1 relied on the neighboring trichloroacetamide group, and stereoselective elaboration of the vinyl group gave α-hydroxylactone 2 , which was transformed into the title compound through a new guanidylation method.     

Porous Silica Particles Prepared from Silicon Tetrachloride Using Ultrasonic Spray Method

Silica particles having the median diameter of 1 to 3 μm were prepared from silicon tetrachloride vapor by a reaction with water droplets using the ultrasonic spray method. The particle sizes of silicas were controlled by changing the composition of silicon tetrachloride and water. These silica particles had microporous structures from nitrogen and water adsorption measurements. The microporous and mesoporous particles were prepared from the reaction of water droplets including sodium and potassium carbonates with silicon tetrachloride vapor. Copyright 1999 Academic Press.     

Asymmetric anionic polymerization of N‐1‐naphthylmaleimide with chiral ligand‐organometal complexes in toluene

Asymmetric anionic homopolymerizations of N‐1‐naphthylmaleimide (1‐NMI) were performed with chiral ligand/organometal complexes to form optically active polymers. Poly(1‐NMI)s obtained with methylene‐bridged bisoxazoline derivatives (Rbox)‐diethylzinc (Et₂Zn) complexes showed high specific optical rotations ([α]) from +152.3 to +191.4°. Circular dichroism spectra of the polymers exhibited a split Cotton effect in the UV absorption‐band region. According to the exciton chirality method, the absolute configuration of the polymer main chain was determined according to the following method: (+)‐poly[N‐substituted maleimides (RMI)] main chains can contain more (S,S)‐ than (R,R)‐configurations. (?)‐Poly(RMI) main chains can contain more (R,R)‐ than (S,S)‐configurations. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3556–3565, 2001     

Synthesis and evaluation of novel 2-oxo-1,2-dihydro-3-quinolinecarboxamide derivatives as potent and selective serotonin 5-HT4 receptor agonists

A series of 8'-substituted N-(endo-8-azabicyclo[3.2.1]oct-3-yl)-1-isopropyl-2-oxo-1,2-dihydro-3-quinolinecarboxamides were synthesized. The 5-HT4 receptor agonistic activity was evaluated using the isolated guinea pig ileum preparation. Of the compounds synthesized, N-(endo-8-(3-hydroxypropyl)-8-azabicyclo[3.2.1]oct-3-yl)-1-isopropyl-2-oxo-1,2-dihydro-3-quinolinecarboxamide (15a, TS-951) exhibited the most potent serotonin 5-HT4 receptor agonistic activity. This compound had a high affinity for the serotonin 5-HT4 receptor although it had no affinities for other broad spectrum receptors. Furthermore, it remarkably enhanced gastrointestinal motility in conscious fed dogs without unfavorable effects that non-selective serotonin 5-HT4 receptor agonist has. TS-951 may be useful in improving gastrointestinal dysfunction.