Reactivity of (2,4-cycloheptadiene-1,6-dione)Fe(CO)3: synthesis of hinokitiol and (7,8-diphenylheptatriafulvalene-1,6-quinone)Fe(CO)3

The reactivities of tricarbonyl(2,4-cycloheptadiene-1,6-dione)iron toward several kinds of nucleophiles and electrophiles were investigated. As a result, it was found that tricarbonyl(2,4-cycloheptadiene-1,6-dione)iron has several reaction sites and undergoes several types of reactions. A new synthetic route to hinokitiol and tricarbonyl-(7,8-diphenylheptariafulvalene-1,6-quinone)iron from (2,4-cycloheptadiene-1,6-dione)iron was explored.     

Improved dissolution of an insoluble drug using a 4-fluid nozzle spray-drying technique

A solid dispersion of the drug can be made using a polymer carrier to improve solubility. Generally, drugs become amorphized when solid dispersion is formed using a polymer carrier. In such high energy conditions, the solubility of the drug molecule is increased. We previously prepared solid dispersion using a spray-drying technique and reported its solubility and crystallinity. In this study, hydroxypropylmethylcellulose (HPMC) was used as the carrier, and tolubutamide was the model drug, which is water-insoluble. Solubility was evaluated by preparing a solid dispersion using a newly developed 4-fluid nozzle spray dryer. Observation of particle morphology by scanning electron microscopy (SEM) revealed that the particles from the spray drying were atomized to several microns, and they had also become spherical. Assessment of the crystallinity of the spray-dried particles by powder X-ray diffraction and differential scanning calorimetry demonstrated that the tolbutamide had been amorphized, forming a solid dispersion. The apparent release rate constant K of the drug from the spray-dried particles was 4 to 6 times faster than the original drug in pH 1.2, and it was also 1.5 to 1.9 times faster than the original drug in pH 6.8. The 70% release time (T(70)) of the drug from the spray-dried particles was 20 to 30 times faster than the original drug in pH 1.2 solution as well as 2 to 3 times faster than the original drug in pH 6.8 solution. Pharmaceutical preparations prepared in this way using the 4-fluid nozzle system spray dryer formed composite particles, resulting in a remarkably improved dissolution rates of the drug.     

Laser-Induced formation of transient polyelectrolyte in solution

Ionic photodissociation of N-ethylcarbazole and poly(N-vinylcarbazole) quenched with dimethylterephthalate was investigated by nanosecond laser photolysis. In the case of the polymer system about a tenth of the carhazole chromophores is ionized by intense laser excitation, which indicates photo-induced formation of a transient polyelectrolyte.     

Characteristics of Diffraction Gratings Fabricated by the Two-Beam Interference Method Using Photosensitive Hybrid Gel Films

Diffraction gratings of arbitrary periods have been fabricated by the two-beam interference method using photosensitive ZrO₂ gel films and characterized. The ZrO₂ gel films were formed on Si or silica glass substrates from sols that were derived from Zr-butoxide modified chemically with benzoylacetone. The gel films were irradiated with two interference beams from a He-Cd laser (325 nm) and then leached in ethyl alcohol. The above process gave uniform surface-relief gratings of periods ranging from 1.0 to 0.5 m, depending on the incidence angle of the interference beams. The diffraction efficiency, measured in the Littrow configuration using a He-Ne laser (633 nm), showed polarization dependence for the grating of 0.5 m period but not for the gratings of 1.0 m period. The maximum diffraction efficiency was 18% for the grating of 1.0 m period and 28% for that of 0.5 m period in the reflection mode. The present study has proved that the photosensitive gel films are versatile in fabrication of optical devices.     

Role of molecular conjugation in the surface radical reaction of aldehydes with H-Si(111): first principles study

Within the current effort to understand and develop the organic functionalization of silicon surfaces, recent experiments have identified the radical chain reaction of unsaturated organic molecules with H-terminated silicon surfaces as a particularly promising route for controlled formation of such functionalized surfaces. Using periodic density functional theory calculations, we theoretically study and characterize the basic steps of the radical chain reaction mechanism for different aldehyde molecules (formaldehyde, benzaldehyde, propanaldehyde, propenaldehyde) reacting with the H-Si(111) surface, under the assumption that a Si dangling bond is initially present on the surface. Molecular conjugation is found to play a crucial role in the viability of the reaction, by controlling the delocalization of the spin density at the reaction intermediate. Interesting differences between our present results for aldehydes and our previous study for the reactions of alkene/alkyne molecules with H-Si(111) are observed and discussed (Takeuchi et al. J. Am. Chem. Soc. 2004, 126, 15890).     

A Stereochemical Study of the Isomerization of Cyclopropyl Ethers to Allyl Ethers Catalyzed with Zinc Iodide

Optically active 1-alkoxybicyclo[4.1.0]heptane was converted using zinc iodide as a catalyst to 2-alkoxymethylidenecyclohexane without loss of optical purity. The mechanism of the isomerization was studied using a stereochemical analysis of the product and deuterium labeling experiments. The results indicated that the isomerization takes place through a stepwise mechanism that involves an attack of zinc iodide on the cyclopropane ring to cause ring opening, followed by an intramolecular 1,2-hydride shift with liberation of the zinc iodide.     

Even dimensional generalization of Chern-Simons action and new gauge symmetry

We propose a new even-dimensional action which shares close algebraic similarities with the Chern-Simons action and thus possesses a topological nature. This action has a new type of gauge symmetry in the sense that adjoint representation is not enough to close the gauge transformation and gauge fermions are incorporated. Quaternionic structure emerges as a natural algebra to control the different natures of even forms, odd forms, bosons and fermions. We claim that the bundle structure in consideration is mathematically a new object.     

Selenium Catalyzed Synthesis of Cyclic Thionecarbamates from Hydroxyisocyanides and Sulfur

Abstracts

1,3-Oxazine-2-thiones were prepared from 3-hydroxyisocyanides and sulfur in the presence of catalytic amounts of selenium.     

Addition of α-hydroxyalkylferrocenes to electrochemically oxidized poly(aniline)

A series of α-hydroxyalkylferrocenes (ferrocenemethanol [FcCH₂OH], α-hydroxyethylferrocene, and 1,1′-ferrocenedimethanol) have been shown to incorporate into highly oxidized films of poly(aniline) [PAn]. Surface immobilization is readily evident in cyclic voltammetric studies by the rapid growth of a pair of sharp redox waves at E_1/2=0.455 V versus SCE in the case of FcCH₂OH. A general mechanism for the attack of α-hydroxyalkylferrocenes on oxidized PAn is inferred from the electrochemical data.     

Evolution of NMDA receptor cytoplasmic interaction domains: implications for organisation of synaptic signalling complexes

Background  

Glutamate gated postsynaptic receptors in the central nervous system (CNS) are essential for environmentally stimulated behaviours including learning and memory in both invertebrates and vertebrates. Though their genetics, biochemistry, physiology, and role in behaviour have been intensely studied in vitro and in vivo, their molecular evolution and structural aspects remain poorly understood. To understand how these receptors have evolved different physiological requirements we have investigated the molecular evolution of glutamate gated receptors and ion channels, in particular the N-methyl-D-aspartate (NMDA) receptor, which is essential for higher cognitive function. Studies of rodent NMDA receptors show that the C-terminal intracellular domain forms a signalling complex with enzymes and scaffold proteins, which is important for neuronal and behavioural plasticity