Mass transfer of weak acid in nanometer-sized pores of octadecylsilyl-silica gel

The sorption of bromophenol blue or anthracene-9-carboxylic acid as a weak acid into single octadecylsilyl (ODS)-silica gel microparticles in a solution was analyzed by microcapillary injection-manipulation and absorption microspectroscopy. The distribution ratio and the sorption rate were highly dependent on the pH of the solution. These results are discussed in terms of the acid dissociation/association, distribution between the ODS and solution phases, and intraparticle diffusion of the weak acid in the nanometer-sized pores of the ODS-silica gel.     

Synthesis of (-)-epibatidine and its derivatives from chiral allene-1,3-dicarboxylate esters

(-)-Epibatidine, an excellent candidate of non-opioidal anesthesia, was formally synthesized in short steps from di-(l)-menthyl (R)-allene-1,3-dicarboxylate that was facilely prepared as a single isomer by means of crystallization-induced asymmetric transformation from a diastereomer mixture of (R)- and (S)-allene-1,3-dicarboxylates. Taking advantage of the chiral synthesis, derivatives of (-)-epibatidine were also prepared for targeting diagnostic agents that could bind nicotinic acetylcholine receptors (nAChRs) in the mammalian central nerve system.     

Preparation of Co–Al and Ni–Al layered double hydroxide thin films by a sol–gel process with hot water treatment

Using hot water treatment of sol–gel derived precursor gel films, Co–Al and Ni–Al layered double hydroxide (LDH) thin films were prepared. The precursor gel films of Al₂O₃–CoO or Al₂O₃–NiO were prepared from cobalt or nickel nitrates and aluminum tri-sec-butoxide using the sol–gel method. Then, the precursor gel films were immersed in a NaOH aqueous solution of 100 °C. Nanocrystallites of Co–Al and Ni–Al LDH were precipitated with the hot water treatment with NaOH solution. The largest amounts of nanocrystals were obtained with a solution of pH = 10 for Co–Al LDH, and with that of pH = 9 for Ni–Al LDH. X-ray diffraction measurements confirmed that this process formed CO₃ ²⁻ intercalated LDHs. Both Co–Al and Ni–Al LDH thin films were confirmed to work as electrodes for electrochemical devices by cyclic voltammogram measurements.     

Water Permeation of SiO2-CH3SiO3/2 Thin Films Modified with Trimethylsilyl Groups on Nylon-6 Substrates

SiO₂-CH₃SiO_3/2 thin films coated on nylon-6 substrates by the sol-gel method were modified with trimethylsilyl (TMS) groups and their water permeability was evaluated. The water permeability coefficient of the nylon-6 substrates coated with TMS-modified SiO₂-CH₃SiO_3/2 thin films was smaller than that of unmodified ones. The wettability for water of SiO₂-CH₃SiO_3/2 thin films modified with TMS was smaller than that of unmodified ones. The decrease in the wettability by the modification with TMS resulted in the decrease in water permeability. The measurements of pore size distribution and the water permeability coefficient of coating films with different pressures of upstream side suggested that the mechanism of permeation was governed by the capillary condensation flow. This mechanism was also supported by the result that the water permeability coefficient was decreased with a decrease in wettability.     

Kinetic analysis of distribution of weak acid in an oil-gelatin microcapsule/water system studied by microcapillary injection and microabsorption methods.

The distribution of anthracene-9-carboxylic acid across dibutyl phthalate/gelatin-membrane/water interface of a single microcapsule was analyzed using microcapillary manipulation and microabsorption methods. The partitioning ratio and the distribution rate in the microcapsule/water system were measured for various pH values in the water phase. Results were compared with those in the dibutyl phthalate/water system in the absence of the gelatin membrane. The distribution rate could be analyzed on the basis of a first-order type reaction. The observed rate constant was linearly proportional to the inverse of the microcapsule radius, indicating that the distribution rate is limited by interfacial mass transfer. Analysis of the pH dependence of the interfacial mass transfer rate suggests that the mass transfer of the neutral species of anthracene-9-carboxylic acid (AnH) competes with the ion transfer of the dissociated species (An-) at the liquid/liquid interface in the gelatin membrane of the microcapsule.     

All-solid-state rechargeable lithium batteries using SnX-P2X5 (X = S and O) amorphous negative electrodes

SnS-P₂S₅ and SnO-P₂O₅ amorphous materials were prepared by a mechanical milling technique. The SnO-P₂O₅ milled materials worked as a reversible electrode with higher capacity than SnO crystal in rechargeable lithium cells with conventional liquid electrolytes. All-solid-state cells with a SnX-P₂X₅ (X = S and O) amorphous electrode and the Li₂S-P₂S₅ glass-ceramic electrolyte were charged and discharged at room temperature. The sulfide electrodes exhibited better charge-discharge performance than the oxide electrodes, suggesting that SnS-P₂S₅ electrodes are more compatible with Li₂S-P₂S₅ sulfide solid electrolytes. All-solid state batteries 80SnS·20P₂S₅/LiCoO₂ showed a charge-discharge plateau of about 3.4 V and high reversible capacity of over 400 mAh/g, even after 50 cycles. The SnX (X = S and O)-based amorphous materials are promising negative electrode materials with high capacity for rechargeable lithium batteries using not only liquid electrolytes but solid electrolytes.     

Fabrication of convex-shaped polybenzylsilsesquioxane micropatterns by the electrophoretic sol–gel deposition process using indium tin oxide substrates with a hydrophobic-hydrophilic-patterned surface

Polybenzylsilsesquioxane (BnSiO_3/2) particles become a supercooled liquid through a heat treatment above the glass transition temperature (T _g) of the particles. Micropatterns of BnSiO_3/2 thick films with high transparency were obtained by the electrophoretic deposition of the BnSiO_3/2 particles on indium tin oxide (ITO)-coated substrates with a hydrophobic-hydrophilic-patterned surface and subsequent heating above T _g of the particles. It was found that the control of electrophoretic deposition conditions, in which the amounts of the particles deposited on the substrates were changed, led to two types of micropatterning processes of the BnSiO_3/2 thick films. In the first process, the particles were selectively deposited on the hydrophilic areas after the electrophoretic deposition. In the second process, the particles were deposited on the whole area of the ITO-coated substrate with hydrophobic-hydrophilic patterns after the electrophoretic deposition. Due to the difference in wettability of BnSiO_3/2 molten liquids between hydrophobic and hydrophilic surfaces, the molten liquids on the hydrophobic areas, which were obtained by heating above T _g of the particles, migrated toward the hydrophilic areas. In both the processes, convex-shaped BnSiO_3/2 micropatterns with high transparency were fabricated only on the hydrophilic areas after a heat treatment above T _g of the particles.     

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%.     

Biomimetic synthesis of (+/-)-galanthamine and asymmetric synthesis of (-)-galanthamine using remote asymmetric induction

(+/-)-Galanthamine (1) was synthesized in excellent yield by applying PIFA-mediated oxidative phenol coupling of N-(4-hydroxy)phenethyl-N-(3',4',5'-trialkoxy)benzyl formamide (15b) as a key step. Because of the symmetrical characteristics of the pyrogallol moiety in the substrate (15b), the phenol coupling resulted in a sole coupling product except for volatile components from the oxidizing agent. On the basis of the successful results of the above strategy, (-)-galanthamine (1) was synthesized by employing a novel remote asymmetric induction, where conformation of the seven-membered ring in the product of the phenol coupling was restricted by forming a fused-chiral imidazolidinone ring with D-phenylalanine on the benzylic C-N bond of the tri-O-alkylated gallyl amino moiety. The conformational restriction and successive debenzylation of the protected hydroxyl groups on the pyrogallol ring caused diastereoselective cyclization to yield a cyclic ether having the desired stereochemistry for the synthesis of (-)-1.