Synthesis of Polyphenylene Thioethers Through Cationic Oxidative Polymerization

Polyaromatic sulfides are efficiently and conveniently prepared by cationic oxidative polymerization. Diphenyl disulfides are quantitatively polymerized to yield poly(p-phenylene sulfide)s as white powders whose structure predominately contains 1,4-phenylene sul-fide bonds. The disulfides are oxidized to phenylbis(phenylthio) sulfonium cations as active species of the polymerization. Repeating the oxidation and electrophilic reaction of the cation to the p-position of disulfides yields the polymer.     

Aqueous electrochemistry of poly(vinylanthraquinone) for anode-active materials in high-density and rechargeable polymer/air batteries

A layer of poly(2-vinylanthraquinone) on current collectors underwent reversible electrode reaction at -0.82 V vs Ag/AgCl in an aqueous electrolyte. A repeatable charging/discharging cycles with a redox capacity comparable to the formula weight-based theoretical density at the negative potential suggested that all of the anthraquinone pendants in the layer was redox-active, that electroneutralization by an electrolyte cation was accomplished throughout the polymer layer, and that the layer stayed on the current collector without exfoliation or dissolution into the electrolyte during the electrolysis. The charging/discharging behavior of the polymer layer in the aqueous electrolyte revealed the capability of undergoing electrochemistry even in the nonsolvent of the pendant group, which offered insight into the nature of the anthraquinone pendants populated on the aliphatic chain. Charging/discharging capability of air batteries was accomplished by using the polymer layer as an organic anode-active material. A test cell fabricated using the conventional MnO(2)/C cathode catalyst exhibited a discharging voltage at 0.63 V corresponding to their potential gap and a charging/discharging cycle of more than 500 cycles without loss of the capacity.     

Thermally induced changes in amorphous indium-tin-oxide thin films

Amorphous indium-tin-oxide (ITO) transparent conducting film (15 at% Sn; thickness, 150–190 nm) was deposited on silicon wafer at room temperature by RF magnetron sputtering for temperature programmed desorption (TPD) in vacuum. The thermal crystallization was accompanied by evolution of water vapor (the main gas), argon and carbon dioxide. The total amount of evolved water vapor (H₂O [mol]/(In [mol]+Sn [mol])>0.2) was one or two orders of magnitude more than that from the nanocrystalline ITO films reported in our previous papers. The thermal change of amorphous ITO film was remarkably affected by the position of the substrate. An abrupt gas evolution was characteristic of the amorphous ITO films deposited on the position near the target center. The evolution temperature (548–563 K) was higher than the gas evolution temperature from the crystalline films. The far from center positioned films crystallized at higher temperature with relatively slower evolution of the gases.     

Capsulation of carbon nanotubes on top of colloidally templated and electropolymerized polythiophene arrays

We describe the capsulation of colloidally templated polythiophene (P3-TAA) arrays with multi-walled carbon nanotubes (MWNTs) after colloidal template electropolymerization. The dissolution of the polystyrene (PS) particle templates, which were assembled via the Langmuir-Blodgett (LB)-like technique, allowed the formation of hollow-shell Janus type arrays.     

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.     

Poly(thiaheterohelicene): a stiff conjugated helical polymer comprised of fused benzothiophene rings

A novel helical aromatic polymer comprised of fused benzothiophene rings, poly(thiaheterohelicene), was synthesized via an intramolecular ring-closing reaction with a controlled helicity to one-sided bias. The synthetic helicity control involved the induction of the helical conformation and its fixation. The ladder polymer showed both an extended pi-conjugation and planarity and a very stiff helical structure. [structure: see text]     

Control of refractive index of sol-gel tungsten oxide films

Tungsten oxide films were prepared by a complexing agent-assisted sol-gel process. All the films were at 500°C were crystalline and transparent. The refractive index n and extinction coefficient k of the films were calculated from the transmittance and reflectance spectra in the visible and infrared regions. The values of n were lowered to depend on the organic ligands used in the preparation of the sols. The use of such ligands may be a mean to control the refractive index of coatings.