Imino ene reaction catalyzed by ytterbium(III) triflate and TMSCl or TMSOTf

A novel combined system of Yb(OTf)(3) with TMSCl or TMSOTf catalyzed an imino ene reaction. The reaction of N-tosylbenzaldimine (1) with alpha-methylstyrene (2) proceeded smoothly to give homoallylic amine 3 in the presence of a catalytic amount of Yb(OTf)(3) and TMSCl. This catalytic system was successfully applied to the imino ene reactions of various aldimines with alkenes. This new imino ene reaction provides a unique method for the three-component coupling reaction of an aldehyde, tosylamide, and alpha-methylstyrene in the presence of Yb(OTf)(3) and TMSOTf, to give the corresponding homoallylic amine.     

Partially nanowire-structured TiO2 electrode for dye-sensitized solar cells

Partially nanowire-structured TiO₂ was prepared by a hydrothermal processing followed by calcination in air. The hydrogen titanate powder as-synthesized was calcined at 300 °C for 4 h to obtain the partially nanowire-structured TiO₂. A dye-sensitized solar cell (DSC) with a film thickness of 5.6 μm, fabricated using the partially nanowire-structured TiO₂ showed better performance than using a fully nanowire-structured TiO₂ or a conventional equi-axed TiO₂ nanopowder. The short-circuit current density (J_SC), the open-circuit voltage (V_OC), the fill factor (FF) and the overall efficiency (η) are 11.9 mA/cm², 0.754 V, 0.673 and 6.01 %, respectively. The effects of one-dimensional nanostructure and electron expressway concept are discussed.     

The Interaction of C60, C70, and C60(CN)2 radical anions with cobalt(II) tetraphenylporphyrin in solid multicomponent complexes

A method for the synthesis of the multicomponent ionic complexes: [Cr(I)(C(6)H(6))(2) (.+)][Co(II)(tpp)(fullerene)(-)].C(6)H(4)Cl(2), comprising bis(benzene)chromium (Cr(C(6)H(6))(2)), cobalt(II) tetraphenylporphyrin (Co(II)(tpp)), fullerenes (C(60), C(60)(CN)(2), and C(70)), and o-dichlorobenzene (C(6)H(4)Cl(2)) has been developed. The monoanionic state of the fullerenes has been proved by optical absorption spectra in the UV/vis/NIR and IR ranges. The crystal structures of the ionic [[Cr(I)(C(6)H(6))(2)](.+)](1.7)[[Co(II)(tpp)(C(60))](2)](1.7-). 3.3 C(6)H(4)Cl(2) and [[Cr(I)(C(6)H(6))(2)] (.+)](2)[Co(II)(tpp)[C(60)(CN)(2)]](-)[C(60)(CN)(2) (.-)]).3 C(6)H(4)Cl(2) are presented. The essentially shortened Co.C(fullerene) bond lengths of 2.28-2.32 A in these complexes indicate the formation of sigma-bonded [Co(II)(tpp)][fullerene](-) anions, which are diamagnetic. All the ionic complexes are semiconductors with room temperature conductivity of 2 x 10(-3)-4 x 10(-6) S cm(-1), and their magnetic susceptibilities show Curie-Weiss behavior. The neutral complexes of Co(II)(tpp) with C(60), C(60)(CN)(2), C(70), and Cr(0)(C(6)H(6))(2), as well as the crystal structures of [Co(II)(tpp)](C(60)).2.5 C(6)H(4)Cl(2), [Co(II)(tpp)](C(70)). 1.3 CHCl(3).0.2 C(6)H(6), and [Cr(0)(C(6)H(6))(2)][Co(II)(tpp)] are discussed. In contrast to the ionic complexes, the neutral ones have essentially longer Co.C(fullerene) bond lengths of 2.69-2.75 A.     

Determination of AJ-3941, a possible agent for the treatment of cerebrovascular disorders, in plasma and brain by means of high-performance liquid chromatography with fluorescence detection.

A sensitive and selective high-performance liquid chromatographic method with fluorescence detection is described for the determination of AJ-3941 (I), a possible agent for the treatment of cerebrovascular disorders, in plasma and brain tissue. A simple hexane extraction was used for plasma, and for brain homogenate the hexane extract was further purified by solid-phase extraction. The determination limit was ca. 3 ng/ml for both plasma (0.5 ml) and 10% (w/v) brain homogenate (1 ml). The method was applied to the determination of I in plasma and brain samples of experimental animals.     

Biomolecular photodiode consisting of cytochrome c-adsorbed hetero-Langmuir–Blodgett films

Photoinduced electron transfer in biomolecular photodiode consisting of protein-adsorbed hetero-Langmuir–Blodgett (LB) films was investigated. Four kinds of functional molecules, cytochrome c, viologen, flavin, and ferrocene, were used as a second electron acceptor, a first electron acceptor, an electron sensitizer, and an electron donor, respectively. The hetero-LB film was fabricated by subsequently depositing ferrocene, flavin, and viologen onto the pretreated ITO glass. Cytochrome c-adsorbed hetero-LB films were prepared by soaking the hetero-LB films into the phosphate buffer solution containing cytochrome c. To verify the optimal adsorption conditions of cytochrome c molecules onto the viologen LB layers, the UV-absorption spectrum and atomic force microscopy observations of LB films were performed. Finally, the metal/insulator/metal structured molecular device was constructed by depositing aluminum onto the surface of the cytochrome c-adsorbed hetero-LB films. For photoelectric response properties, the current–voltage characteristic and photoswitching effect of the proposed molecular photodiode were investigated. To verify the charge shift, transient photocurrent of the molecular photodiode was measured.     

The synthesis of benzofuroquinolines. X. Some benzofuro[3,2-c]isoquinoline derivatives

Condensation of salicylonitrile with ethyl α-bromo-α-(o-ethoxycarbonylphenyl)acetate (4) effectively gave 5 (6H)-benzofuro[3,2-c]isoquinolinone (2) , which was converted to some 5-substituted benzofuro-[3,2-c]isoquinoline derivatives 1a-g.     

Formation of single-bonded (C60-)2 and (C70-)2 dimers in crystalline ionic complexes of fullerenes

New ionic complexes of fullerenes C(60) and C(70) with decamethylchromocene Cp*(2)Cr.C60.(C(6)H(4)Cl(2))(2) (1), Cp*(2)Cr.C60.(C(6)H(6))(2) (2); the multicomponent complex of (Cs(+))(C70-) with cyclotriveratrylene CTV.(Cs)(2).(C70)(2).(DMF)(7).(C(6)H(6))(0.75) (3); bis(benzene)chromium Cr(C(6)H(6))(2).C60.(C(6)H(4)Cl(2))(0.7) (4), Cr(C(6)H(6))(2).C60.C(6)H(5)CN (5), Cr(C(6)H(6))(2).C70.C(6)H(4)Cl(2) (6), Cr(C(6)H(6))(2).C60 (7); cobaltocene Cp(2)Co.C60.C(6)H(4)Cl(2) (8), Cp(2)Co.C70.(C(6)H(4)Cl(2))(0.5) (9); and cesium Cs.C70.(DMF)(5) (10) have been obtained. The complexes have been characterized by the elemental analysis, IR-, UV-vis-NIR spectroscopy, EPR and SQUID measurements. It is shown that C(60)(.-) exists as a single-bonded diamagnetic (C60-)2 dimer in 1, 2, 4, 5, and 8 at low temperatures (1.9-250 K). The dimers dissociate above 160-250 K depending on donor and solvent molecules involved in the complex. C60(.-) dimerizes reversibly and shows a small hysteresis (<2 K) at slow cooling and heating rates. The single-bonded diamagnetic (C70-)2 dimers are also formed in 6, 9, and 10 and begin to dissociate only above 250-360 K. The IR and UV-vis-NIR spectra of sigma-bonded negatively charged fullerenes are presented.     

Precocentration method using an activatable yield tracer for neutron activation analysis

Previously, the use of an enriched stable isotope as an activatable yield tracer in preconcentration steps has been tested by use of commercially available enriched¹¹⁶Cd and¹⁵⁶Dy for biological standard reference materials.^1,2 In the present work, this method has been further applied to the determination of lanthanoid contents in various kinds of samples: one coal fly-ash, three Japanese standard rocks, and eight standard soils. Samples were decomposed by alkali fusion in the preconcentration step. Thirteen elements were determined for coal fly-ash and soil samples, and 14 elements for rocks. The data obtained for coal fly-ash and standard rocks are compared with the data reported in literature. The data for soil samples have been newly determined in the present work. The ordinary instrumental neutron activation analysis and radiochemical neutron activation analysis were also performed to confirm the accuracy and usefulness of the present method.     

Tunable metallization by assembly of metal nanoparticles in polymer thin films by photo- or electron beam lithography

The technique of patterning of surfaces with metal-rich structures on micro- or nanoscales was developed by assembling metal nanoparticles into a thin film of polymer in a controllable way. Palladium (Pd) nanoparticles were incorporated into a thin film of poly(methyl methacrylate) (PMMA) using palladium (II) bis(acetylacetonato), Pd(acac)(2), as a precursor vaporized in a nitrogen atmosphere. Depending upon its dose, the irradiation of a PMMA film by UV light or an electron beam (EB) enhances its reducing capability against Pd(acac)(2). This dependency on dose can be used to control the formation and assembly of Pd nanoparticles. Using this technique, binary patterns consisting of metal-rich and metal-poor regions in the polymer film can be created simply by irradiating the surface of the polymer through a binary photomask. Besides the creation of binary patterns, it is also possible to create grayscale patterns where the density of Pd nanoparticles can be tuned to provide shades of gray by the use of light with continuously modulated intensity. Because the electron beam also enhances the reducing power of PMMA against Pd(acac)(2), it is thus possible to obtain highly metallized films with nanoscale pattern features. The PMMA film can be selectively removed by oxygen plasma treatment or by pyrolysis. Thus, highly metallized surfaces with binary or grayscale patterns can be obtained by selective removal of the PMMA films. The metallized regions possess relatively high resistivity against CF(4) plasma compared to the bare silicon surface; therefore, the metallized surface patterns can be transferred onto the underlying silicon substrate by CF(4) plasma treatment. Because of the nanosize effect of metal nanoparticles, the thermal treatment at 900 degrees C, which is significantly lower than the melting temperature of the bulk Pd, yields continuous metallic features by binding the assembled nanoparticles.     

Catalytic mechanism of heme oxygenase through EPR and ENDOR of cryoreduced oxy-heme oxygenase and its Asp 140 mutants

Heme oxygenase (HO) catalyzes the O(2)- and NADPH-cytochrome P450 reductase-dependent conversion of heme to biliverdin, Fe, and CO through a process in which the heme participates both as a prosthetic group and as a substrate. In the present study, we have generated a detailed reaction cycle for the first monooxygenation step of HO catalysis, conversion of the heme to alpha-meso-hydroxyheme. We employed EPR (using both (16)O(2) and (17)O(2)) and (1)H, (14)N ENDOR spectroscopies to characterize the intermediates generated by 77 K radiolytic cryoreduction and subsequent annealing of wild-type oxy-HO and D140A, F mutants. One-electron cryoreduction of oxy-HO yields a hydroperoxoferri-HO with g-tensor, g = [2.37, 2.187, 1.924]. Annealing of this species to 200 K is accompanied by spectroscopic changes that include the appearance of a new (1)H ENDOR signal, reflecting rearrangements in the active site. Kinetic measurements at 214 K reveal that the annealed hydroperoxoferri-HO species, denoted R, generates the ferri-alpha-meso-hydroxyheme product in a first-order reaction. Disruption of the H-bonding network within the distal pocket of HO by the alanine and phenylalanine mutations of residue D140 prevents product formation. The hydroperoxoferri-HO (D140A) instead undergoes heterolytic cleavage of the O-O bond, ultimately yielding an EPR-silent compound II-like species that does not form product. These results, which agree with earlier suggestions, establish that hydroperoxoferri-HO is indeed the reactive species, directly forming the alpha-meso-hydroxyheme product by attack of the distal OH of the hydroperoxo moiety at the heme alpha-carbon.