On the assignment of the absolute configuration at the isolated methyl branch in miyakosyne A,cytotoxic linear acetylene,from the deep-sea marine sponge Petrosia sp.

Absolute configuration of miyakosyne A at its isolated branched methyl stereogenic center has been studied by chemical degradation in combination with esterification with the Ohrui's acid. Comparison of the ¹H NMR data of the relevant diesters for the degradation product and the synthetic standards indicated the 14R-configuration.     

Synthetic study and structure of cage-type cyclophane C36H36S6

A cage compound was synthesized in order to investigate the structure and cation-π interactions of the metal ion complex. The multi-step synthesis was achieved starting from trimesic acid triethyl ester. In solution, a completely symmetrical structure that was anticipated by the molecular design was observed by ¹H and ¹³C NMR spectroscopy. However, in the solid state, X-ray crystallographic analysis revealed that the compound had a collapsed structure.     

Spatially controlled Suzuki and Heck catalytic molecular coupling

The initiation and control of chemical coupling has the potential to offer much within the context of "bottom up" nanofabrication. We report herein the use of a palladium-modified, catalytically active, AFM probe to initiate and spatially control surface-confined Suzuki and Heck carbon-carbon coupling reactions. These "chemically written reactions", detectable by lateral force and chemically specific optical and topographic labeling, were patterned with line widths down to 15 nm or approximately 20 molecules. Catalyzed organometallic coupling was, in this way, carried out at subzeptomolar levels. By varying the catalyst-substrate interaction times, turnover numbers of (0.6-1.2) x 10(4) and (3.0-5.0) x 10(4) molecules s(-1) were resolved for Suzuki and Heck reactions, respectively.     

Formation of a highly ordered dot array of surface micelles of a block copolymer via liquid crystal-hybridized self-assembly

A highly ordered dot array pattern of surface micelles on water is formed by a spread monolayer of an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-4VP), via hybridization with a liquid crystal molecule, 4'-pentyl-4-cyanobiphenyl (5CB), on water. Simple co-spreading of PS-4VP with 5CB provides a flat homogeneous monolayer of PS-4VP on water without the aggregation of PS blocks. With increasing surface pressure, well-defined dots of the PS blocks start to grow and are arrayed in a highly ordered hexagonal structure. The exact coincidence of the surface pressure-area curves for the hybrid monolayer in the compression and expansion processes confirms that the flat spread monolayer and the dot array are formed on water in the equilibrium state by a self-assembly process.     

Structures and phase transition of multi-layered water nanotube confined to nanochannels

We placed nanometer-scale water-tube clusters with phase transition within a porous crystal formed from molecular blocks specifically designed to investigate the molecular dynamics of confined water molecules.     

Thioridazine induces immediate and delayed erythema in photopatch test

Thioridazine is a phenothiazine derivative that has been used as an antipsychotic; it rarely causes photosensitization. However, we noticed that this drug induced an erythematous reaction in a photopatch test. Six volunteers were patch tested with various concentrations of thioridazine and irradiated with a range of UVA doses, and the time courses of the color of and blood flow to the test sites were monitored. The free-radical metabolites of thioridazine generated under UVA irradiation and its effects on ascorbate radical formation were examined with an electron paramagnetic resonance (EPR) spectrometer in vitro. As a result, immediate erythema developed during UVA irradiation in most subjects when 1% thioridazine was applied for 48 h and irradiation doses were higher than 4 J cm(-2). Another peak of erythematous reaction was observed 8-12 h after irradiation. The in vitro examination detected an apparent EPR signal, which appeared when 2 mM thioridazine in air-saturated phosphate buffer was irradiated with UVA, whereas this reaction was attenuated under anaerobic conditions. The EPR signal of the ascorbate radical was augmented under both aerobic and anaerobic conditions. Thioridazine-derived oxidants and/or thioridazine radicals generated during UVA irradiation seem to play an important role in this unique phototoxic reaction.     

Low-birefringent, chiral banana phase below calamitic nematic and/or smectic C phases in oxadiazole derivatives

Bent-shaped molecules based on the oxadiazole central core with various side wings and terminal chain groups have been synthesized, and their liquid-crystalline behavior was investigated by optical microscopic, X-ray, and electrooptic measurements. These molecules exhibit liquid-crystal polymorphism including both the calamitic and banana phases. Such a characteristic polymorphism is attributable to the larger bend angle of the oxadiazole core compared to that of the resorcinol core used in conventional banana molecules. Only one type of banana phase, designated as the Bx phase, is formed. It appears upon cooling from the nematic and smectic liquid crystals and exhibits chiral domains with a very weak birefringence (apparently optically isotropic). By applying an electric field, the Bx phase is altered to a high-birefringence B2 phase with a homochiral SmC(A)P(A) structure that exhibits an antiferroelectric response. From detailed analyses of the optical texture and X-ray patterns through the transformation from well-oriented calamitic phases, the Bx phase was found to exhibit a helical structure, which arises as a frustration from the ground-state B2 phase in such a manner that the blocks of B2 layers are twisted with respect to each other in a direction parallel to the layer plane similarly to the twisted grain boundary (TGB) phase.     

Selective encapsulation-release and photodegradation characteristics of organic dyes by cross-linked fluoroalkyl end-capped oligomeric nanocomposites possessing aromatic siloxane segments as core units

Cross-linked fluoroalkyl end-capped oligomeric nanocomposites possessing aromatic siloxane segments as core units [R_F-oligomer/Ar-SiO ₂ ] exhibited an encapsulation ability toward organic dyes such as methylene blue (MB), rhodamine B (RB), 4-hydroxyazobenzene-4′-sulfonic acid sodium salt, and methyl orange (MO). In these organic dyes, MB and RB are effectively encapsulated into these nanocomposites in aqueous solutions. R_F-oligomer/Ar-SiO ₂ nanocomposite-encapsulated organic dyes were found to exhibit a controlled releasing characteristic toward these encapsulated dyes, and encapsulated MB was not released into water; however, this encapsulated dye was smoothly released into acetone under similar conditions. Interestingly, R_F-oligomer/Ar-SiO ₂ nanocomposites possessing biphenylene segments as core units were able to exhibit not a photostable characteristic but extremely higher photodegradation ability toward MO under UV light irradiation.