Hexakis(2-pyridyl)- and hexakis(3-pyridyl)[3]radialene: novel,water-soluble [3]radialenes with potential utility for supramolecular chemistry

The titled [3]radialenes are the first, water-soluble hexaaryl[3]radialenes with considerably high electron affinity, their alkali metal reduction giving rise to anion-radicals and dianions stepwise as fairly stable species in degassed tetrahydrofuran.     

Arg-72 of pharaonis phoborhodopsin (sensory rhodopsin II) is important for the maintenance of the protein structure in the solubilized states

In bacteriorhodopsin (bR), Arg-82bR has been proven to be a very important residue for functional role of this light-driven proton pump. The arginine residue at this position is a super-conserved residue among archaeal rhodopsins. pharaonis phoborhodopsin (ppR; or called as "pharaonis sensory rhodopsin II") has its absorption maximum at 498 nm and acts as a sensor in the membrane of Natronobacterium pharaonis, mediating the negative phototaxis from the light of wavelength shorter than 520 nm. To investigate the role of the arginine residue (Arg-72ppR) of ppR corresponding to Arg-82bR, mutants whose Arg-72ppR was replaced by alanine (R72A), lysine (R72K), glutamine (R72Q) and serine (R72S) were prepared. These mutants were unstable in low concentrations of NaCl and lost their color gradually when the proteins were solubilized with 0.1% n-dodecyl-beta-D-maltoside. The order of instability was R72S > R72A > R72K > R72Q > the wild type. The rates of denaturation were reduced in a solution of high concentrations of monovalent anions.     

A validated LC‐MS/MS method for the determination of canagliflozin,a sodium–glucose co‐transporter 2 (SGLT‐2) inhibitor,in a lower volume of rat plasma: application to pharmacokinetic studies in rats

Canagliflozin is a novel, orally selective inhibitor of sodium‐dependent glucose co‐transporter‐2 (SGLT2) for the treatment of patients with type 2 diabetes mellitus. In this study, a validated liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for the quantitative analysis of canagliflozin in a lower volume of rat plasma (0.1 mL) was established and applied to a pharmacokinetic study in rats. Following liquid–liquid extraction by tert‐butyl methyl ether, chromatographic separation of canagliflozin was performed on a Quicksorb ODS (2.1 mm i.d. × 150 mm, 5 µm size) using acetonitrile–0.1% formic acid (90:10, v/v) as the mobile phase at a flow rate of 0.2 mL/min. The detection was carried out using an API 3200 triple‐quadrupole mass spectrometer operating in the positive electrospray ionization mode. Selected ion monitoring transitions of m/z = 462.0 [M + NH₄]⁺ → 191.0 for canagliflozin and m/z = 451.2 [M + H]⁺ → 71.0 for empagliflozin (internal standard) were obtained. The validation of the method was investigated, and it was found to be of sufficient specificity, accuracy and precision. Canagliflozin in rat plasma was stable under the analytical conditions used. This validated method was successfully applied to assess the pharmacokinetics of canagliflozin in rats using 0.1 mL rat plasma. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and characterization of silica-pillared derivatives from kanemite

The silica-pillared derivatives from kanemite (NaHSi(2)O(5).3H(2)O) were prepared by intercalation of dialkyldimethylammonium (DADMA) ion and pillaring with tetraethylorthosilicate. The formation of silica pillars between the silicate sheets was demonstrated by X-ray diffraction, (29)Si CP/MAS NMR, and TEM observation. The basal spacing depended on the chain length of DADMA. Nitrogen adsorption study showed that the specific surface area was enlarged over 1000 m(2) g(-1) by the pillaring and that the pore size was in the micropore region. Water and benzene adsorption isotherms revealed that the surface properties of the pillared derivatives show hydrophobic character.     

Carboxamidation of carboxylic acids with 1-tert-butoxy-2-tert-butoxycarbonyl-1,2-dihydroisoquinoline (BBDI) without bases

Formation of carboxamides of a variety of carboxylic acids with the coupling reagent BBDI is described. This procedure permits a one pot and simple operation without the need of any bases and no base was required for even use of amine hydrochlorides. In addition, an approach to BBDI-catalyzed carboxamidation is examined.     

Reactive regioregular oligothiophenes and polythiophenes with Zincke salt structure: Synthesis,reactions, and chemical properties

Polythiophenes with reactive Zincke salt structure, P4ThPy⁺DNP(Cl^?)‐a and P5ThPy⁺DNP(Cl^?)‐a , were synthesized by the oxidation polymerization of oligothiophenes, such as 3'‐(4‐N‐(2,4‐dinitrophenyl)pyridinium chloride)?2,2':5',2'';5'',2'''‐quarterthiophene ( 4ThPy⁺DNP(Cl^?) ) and 4''‐(4‐N‐(2,4‐dinitrophenyl)pyridinium chloride)?2,2';5',2'';5'',2''';5''',2''''‐quinquethiophene ( 5ThPy⁺DNP(Cl^?) ), with iron(III) chloride. The reaction of P5ThPy⁺DNP(Cl^?)‐a with R‐NH₂ [R = n‐hexyl (Hex) and phenyl (Ph)] substituted the 2,4‐dinitrophenyl group into the R group with the elimination of 2,4‐dinitroaniline to yield P5ThPy⁺R(Cl^?) . Similarly, model compounds, 4ThPy⁺R(Cl^?) and 5ThPy⁺R(Cl^?) (R = Hex and Ph), were also synthesized. In contrast to the photoluminescent 4ThPy and 5ThPy , the compounds P4ThPy⁺DNP(Cl^?)‐a , P5ThPy⁺DNP(Cl^?)‐a , and P5ThPy⁺R(Cl^?) showed no photoluminescence because their internal pyridinium rings acted as quenchers. Cyclic voltammetry measurements suggested that P4ThPy⁺DNP(Cl^?)‐a , P5ThPy⁺DNP(Cl^?)‐a , and P5ThPy⁺R(Cl^?) received an electrochemical reduction of the pyridinium and 2,4‐dinitrophenyl groups and oxidation of the polymer backbone. P4ThPy⁺DNP(Cl^?)‐a and P5ThPy⁺DNP(Cl^?)‐a were electrically conductive (ρ = 3.0 × 10 ^{? 6} S cm ^{? 1} and 2.1 × 10 ^{? 6} S cm ^{? 1}, respectively) in the nondoped state. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 481–492     

Stereoinvertive C–C Bond Formation at the Boron-Bound Stereogenic Centers through Copper-Bipyridine-Catalyzed Intramolecular Coupling of α-Aminobenzylboronic Esters

Enantiospecific intramolecular Suzuki–Miyaura-type coupling with α-(2-halobenzoylamino)benzylboronic esters to give 3-substituted isoindolinones is achieved by using copper catalysts with 2,2′-bipyridine-based achiral ligands. Enantioenriched α-aminobenzylboron reactants bearing a hydrogen atom at the boron-bound stereogenic carbons undergo stereoinvertive coupling in the presence of a 6-phenyl-2,2′-bipyridine ligand with high enantiospecificity. α-Aminobenzylboronates bearing fully substituted boron-bound stereogenic centers also gave the 3,3-disubstituted isoindolinones with stereospecific stereochemical inversion in the presence of simple 2,2′-bipyridine as a ligand.     

A video camera system for coaxial observation of a sample with an incident soft X‐ray beam

A video camera system for observing a sample from the direction of an incident soft X‐ray beam has been developed. The sample is seen via two reflecting mirrors. The first mirror, which has a hole to allow the soft X‐ray beam to pass through, is set on the beam axis in a vacuum. The second mirror is used to cancel out the mirror inversion of the image. This camera system is used for efficient positioning of samples in a soft X‐ray beam.     

Oxygen ion conductivity of yttria-niobia mixed oxide with fluoride related structure

The oxygen ion conductivity of Y₂O₃---Nb₂O₅ with a fluorite-like structure was studied. Substitutional solid solutions of Nb₂ O₅ in Y₂O₃ lattice formed the defect fluorite phase and remarkably enhanced the oxygen ion conductivity. Doping with tetravalent cations, especially Ti⁴⁺ or Ce⁴⁺, in yttria-niobia oxide is effective in enhancing the oxygen ion conductivity. Although the n-type semiconducting property appeared below P_O2 = 10⁻¹⁸ atm at 1243 K, the yttria-niobia mixed oxide doped with Ce⁴⁺, Ti⁴⁺, and Zr⁴⁺ stably exhibited oxygen-ion conduction in the wide range of oxygen partial pressures studied.     

A novel 1-tert-butoxy-2-tert-butoxycarbonyl-1,2-dihydroisoquinoline (BBDI)-catalyzed esterification of N-protected amino acids with nearly equimolar amounts of alcohols in the presence of Boc2O

A very mild, BBDI-catalyzed esterification using approximately equimolar amounts of N-protected amino acids and alcohols, in junction with Boc₂O is described.