Asymmetric reduction of aromatic ketimines in the presence of helical polymer as catalyst

Novel optically active ethynyl monomers were synthesized from L ‐valine and N‐methyl‐L ‐valine, and polymerized with a rhodium catalyst to provide the polymers with number‐average molecular weights over 200,000 in good yields. The CD and UV‐vis spectra of the polymers indicated that they took helical structures with predominantly one‐handed screw sense in solution. The polymers served as catalysts of asymmetric reduction of aromatic ketimines to afford optically active amines in moderate yields. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4971–4981, 2009     

Tin oxide coating on polytetrafluoroethylene films in aqueous solutions

Polytetrafluoroethylene (PTFE) films were successfully coated with tin oxide in aqueous solutions. Tin oxide was crystallized in the solution and formed nanocrystal coatings on the polymer films. The coatings consisted of SnO₂ and SnO crystals. They were assemblies of tin oxide nanosheet of about 10 to 50 nm in size and about 5 nm in thickness. The nanocrystal films can be exfoliated from the PTFE substrates. Tin oxide nanocrystal films had a rough liquid surface and a dense substrate‐side surface. Transparency of PTFE films coated with tin oxide was same as that of bare PTFE films in the range from 400 to 800 nm. The PTFE films coated with tin oxide nanocrystals can be pasted on desired substrates. Copyright © 2009 John Wiley & Sons, Ltd.     

Confinement Effect of Organic Nanotubes Toward Green Fluorescent Protein (GFP) Depending on the Inner Diameter Size

Transportation, release behavior, and stability of a green fluorescent protein (GFP, 3×4 nm) in self‐assembled organic nanotubes with three different inner diameters (10, 20, and 80 nm) have been studied in terms of novel nanocontainers. Selective immobilization of a fluorescent acceptor dye on the inner surface enabled us to not only visualize the transportation of GFP in the nanochannels but to also detect release of the encapsulated GFP to the bulk solution in real time, based on fluorescence resonance energy transfer (FRET). Obtained diffusion constants and release rates of GFP markedly decreased as the inner diameter of the nanotubes was decreased. An endo‐sensing procedure also clarified the dependence of the thermal and chemical stabilities of the GFP on the inner diameters. The GFP encapsulated in the 10 nm nanochannel showed strong resistance to heat and to a denaturant. On the other hand, the 20 nm nanochannel accelerated the denaturation of the encapsulated GFP compared with the rate of denaturation of the free GFP in bulk and the encapsulated GFP in the 80 nm nanochannels. The confinement effect based on rational fitting of the inner diameter to the size of GFP allowed us to store it stably and without denaturation under high temperatures and high denaturant concentrations.     

Pulsed EPR Analysis of the Photo-Induced Triplet Radical Pair in the BLUF Protein SyPixD: Determination of the Protein–Protein Distance and Orientation in the Oligomeric Protein

A photo-induced radical pair of FADH^· and Y8^· and in BLUF protein SyPixD was studied by pulsed electron paramagnetic resonance (EPR) spectroscopy. Blue light illumination at 150 K for 30 min followed by cooling to 50 K during illumination induced the stable radical pair. The EPR signal has been characterized by a Pake doublet signal with complete S = 1 spin state. The radical pair was utilized as a probe to analyze the oligomer of SyPixD. The relative arrangement of PixD proteins in the complex was investigated by pulsed electron–electron double resonance (PELDOR) with the orientation selection. Based on the decameric structure in the crystal, the possible structure for the PELDOR results was discussed.     

Effect of Dissolved Oxygen on the Reduction of Stable Nitroxide by Ascorbic Acid: In Vitro Model for Acute Hypoxia Ischemia

The reaction between 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (PCAM), which is a blood–brain-barrier (BBB) permeable stable cyclic nitroxide, and ascorbic acid was examined in a low dissolved oxygen-phosphate buffer (low DO-PB, 0.1 mM DO) under 8% oxygen in a glove bag or in an ordinal dissolved oxygen-phosphate buffer (ordinal DO-PB, 0.3 mM DO) under 21% oxygen in an open atmosphere with and without diethylenetriaminepentaacetic acid (DTPA). In PB with DTPA, no difference was observed between the results in the low DO-PB and those in the ordinal DO-PB. In the ordinal DO-PB without DTPA, the rate constant of the PCAM decrease was half that in the low DO-PB without DTPA. The present results indicate that high DO and coexisting transition metal ions caused the oxidation of ascorbic acid, which degraded the PCAM reduction. The stable nitroxide-ascorbic acid system without DTPA was found to be applicable to an in vitro model for the acute hypoxia ischemia.     

Toric origami manifolds and multi-fans

The notion of a toric origami manifold, which weakens the notion of a symplectic toric manifold, was introduced by A. Cannas da Silva, V. Guillemin and A.R. Pires. They showed that toric origami manifolds bijectively correspond to origami templates via moment maps, where an origami template is a collection of Delzant polytopes with some folding data. Like a fan is associated to a Delzant polytope, a multi-fan introduced by A. Hattori and M. Masuda can be associated to an oriented origami template. In this paper, we discuss their relationship and show that any simply connected compact smooth 4-manifold with a smooth action of T ² can be a toric origami manifold. We also characterize products of even dimensional spheres which can be toric origami manifolds.     

Novel potassium channel activators. II. Synthesis and pharmacological evaluation of 3,4-dihydro-2H-1,4-benzoxazine derivatives: modification of the aromatic part.

Three new series of analogues related to 3,4-dihydro-2H-1,4-benzoxazine derivative 1a were synthesized and evaluated for their potassium channel activating activity. In the first series I, where the 6,7-positions were disubstituted, it was found that an electron-withdrawing substituent was preferable at the 6 position, but either an electron-withdrawing or releasing substituent without bulkiness was tolerated at the 7 position. In the second series II, where several heterocycles were introduced into the 6,7-positions, the oxadiazole derivative 6 showed more potent activity than cromakalim. In the third series III, where the benzene ring was replaced by a pyridine ring, borane complex 16 had equivalent activity to cromakalim. Especially, compound 6 showed a potent hypotensive effect with a long duration of action in the spontaneous hypertensive rat and had a lesser increasing effect on intracranial pressure in dogs than 1a and levcromakalim, showing a good profile as an antihypertensive agent.     

Microwave-assisted synthesis of (tris-acetylacetonato)(2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline)terbium(III) complex with outstanding high green luminescence

Microwave-assisted synthesis method enabled the preparation of the (tris-acetylacetonate)(2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinate) terbium(III) (Tb(acac)₃(dmdpphen)) complex with outstanding high green luminescence. This method is appropriate for green chemistry and energy-saving processes. The Tb(acac)₃(dmdpphen) complex has good thermal stability. Emission peaks are assigned to the f-f transitions of the Tb³⁺. The Tb(acac)₃(dmdpphen) complex is expected to be used in functional materials of electronic products.     

Kernel identities for van Diejen’s q-difference operators and transformation formulas for multiple basic hypergeometric series

The kernel function of Cauchy type for type BC is defined as a solution of linear q-difference equations. In this paper, we show that this kernel function intertwines the commuting family of van Diejen’s q-difference operators. This result gives rise to a transformation formula for certain multiple basic hypergeometric series of type BC. We also construct a new infinite family of commuting q-difference operators for which the Koornwinder polynomials are joint eigenfunctions.